WO2025115233A1 - Method for separating and recovering rare earth component and metal component from post-calcination waste of multilayer ceramic capacitor - Google Patents

Abstract

The present invention provides a method for separating and recovering a rare earth component and a metal component from a post-calcination waste. This separation and recovery method includes: (A) a step for preparing a post-calcination waste of a multilayer ceramic capacitor in which a ceramic layer, an internal electrode layer containing a first metal component that has magnetic properties, and a baked electrode layer containing a second metal component that does not have magnetic properties are sintered; (B) a step for refining the post-calcination waste; (C) a step for separating and recovering, with use of a magnet, a first separated material that contains a refined ceramic and a refined first metal, and a second separated material that contains a refined ceramic, a rare earth-containing material, and a refined second metal; (D) a step for dissolving the second separated material into a mineral acid that has no oxidizing power, and precipitating the refined ceramic and the refined second metal, thereby generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing material is dissolved; and (E) a step for dissolving the precipitate in the second separated material into ammonia water, thereby generating a second metal solution in which the second metal component in the refined second metal is dissolved.

Description

Method for separating and recovering rare earth and metal components from post-sintering waste of multilayer ceramic capacitors

This invention relates to a method for separating and recovering rare earth and metal components from post-sintering waste from multilayer ceramic capacitors.

A large demand is expected for multilayer ceramic capacitors (MLCCs) as electronic components mounted on automobiles, electronic components for mobile phones, etc. A multilayer ceramic capacitor includes a laminate having an internal electrode layer and a ceramic layer, and an external electrode. The internal electrode layer contains a metal component such as Ni, and the ceramic layer is formed of BaTiO ₃ , etc. Patent documents 1 to 4 disclose a method for recovering Ni, which is mainly used in the internal electrode layer, and also disclose that BaTiO ₃ contained in the ceramic layer is separated in the process of recovering Ni.

JP 2003-253347 A JP 2003-268459 A JP 2003-277843 A JP 2003-277846 A

Some of the raw materials used to manufacture multilayer ceramic capacitors contain not only Ni but also rare earth components. Patent documents 1 to 4 disclose the recovery of Ni, but do not disclose the recovery of rare earth components. However, it is desirable to be able to recover not only metal components such as Ni, but also rare earth components.

Therefore, the main object of this invention is to provide a method for separating and recovering rare earth and metal components from post-sintering waste of multilayer ceramic capacitors.

The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention comprises the steps of:
(A) preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising a laminate including a ceramic layer and an internal electrode layer, and a fired electrode layer disposed on the laminate as an outermost layer and connected to the internal electrode layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material including a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer includes a first metal component which is a magnetic base metal, the fired electrode layer includes a second metal component which is a non-magnetic precious metal, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) A step of obtaining a ceramic fine-particle having a fine ceramic layer, a rare earth-containing material, a first metal fine-particle having a fine internal electrode layer, and a second metal fine-particle having a fine baked electrode layer by pulverizing the fired waste material;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated matter containing the ceramic fine particles and the first fine metal particles, and a second separated matter containing the ceramic fine particles, the rare earth-containing matter, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second fine particles of the metal in the second separated product and generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing product is dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separated product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separated product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
Equipped with.

According to this invention, rare earth components and metal components can be separated and recovered from the post-sintering waste. In particular, as metal components, a first metal component contained in the internal electrode layer and a second metal component contained in the external electrode can be separated and recovered.

The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention comprises the steps of:
(A) a step of preparing fired waste of a multilayer ceramic capacitor, the fired waste comprising a laminate including a ceramic layer and an internal electrode layer, a fired electrode layer disposed on the laminate and connected to the internal electrode layer, and a first-stage plating layer disposed on the fired electrode layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, rare earth-containing matter containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component which is a magnetic base metal, the fired electrode layer contains a second metal component which is a non-magnetic precious metal, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) A step of pulverizing the fired waste to obtain a ceramic micro-fine product having a fine ceramic layer, a rare earth-containing material, a first metal micro-fine product having a fine internal electrode layer and a fine first-stage plating layer, and a second metal micro-fine product having a fine baked electrode layer;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated matter containing the ceramic fine particles and the first fine metal particles, and a second separated matter containing the ceramic fine particles, the rare earth-containing matter, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second fine particles of the metal in the second separated product and generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing product is dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separated product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separated product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
Equipped with.

According to this invention, rare earth components and metal components can be separated and recovered from the post-sintering waste. In particular, as metal components, a first metal component contained in the internal electrode layer and a second metal component contained in the external electrode can be separated and recovered.

The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to the present invention comprises the steps of:
(A) a step of preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; a first-stage plating layer disposed on the fired electrode layer; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles; the internal electrode layer includes a first metal component which is a base metal having magnetism; the fired electrode layer includes a second metal component which is a precious metal having no magnetism; the first-stage plating layer includes the first metal component; the second-stage plating layer includes a third metal component; and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(K) removing at least the second-stage plating layer from the first-stage plating layer and the second-stage plating layer in the fired waste;
(B) a step of pulverizing the fired waste from which at least the second-stage plating layer has been removed through the step (K) to obtain a ceramic micro-particle having a micro-particle of the ceramic layer, a rare earth-containing material, a first metal micro-particle having a micro-particle of the internal electrode layer and the first-stage plating layer, and a second metal micro-particle having a micro-particle of the baked electrode layer;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated matter containing the ceramic fine particles and the first fine metal particles, and a second separated matter containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second fine particles of the metal in the second separated product and generating a rare earth component-containing solution in which the rare earth component in the rare earth-containing product is dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separated product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separated product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
Equipped with.

According to this invention, rare earth components and metal components can be separated and recovered from the post-sintering waste. In particular, as metal components, a first metal component contained in the internal electrode layer and a second metal component contained in the external electrode can be separated and recovered.

This invention provides a method for separating and recovering rare earth and metal components from post-sintering waste from multilayer ceramic capacitors.

The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the invention, which refers to the drawings.

FIG. 1 is a flow diagram showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers), according to a first embodiment of the present invention. 1 is an external perspective view showing an example of a multilayer ceramic capacitor according to a first embodiment of the present invention; 3 is a cross-sectional view taken along line III-III in FIG. 2. 2 is a schematic diagram showing the state of unsintered ceramic layers and unsintered internal electrode layers in a cross section parallel to a plane including the longitudinal direction and stacking direction in a laminated chip. FIG. FIG. 4 is an enlarged view of a portion α in FIG. 3, and is a schematic diagram showing the state of each layer after firing for a fired electrode layer. FIG. 6 is a partial enlarged view of the ceramic layer of FIG. 5 . 1 is a cross-sectional view (1) of a multilayer ceramic capacitor according to a second embodiment of the present invention, taken along a plane including the length direction and lamination direction. FIG. 11 is a cross-sectional view (2) of another aspect of the multilayer ceramic capacitor according to the second embodiment of the present invention, taken along a plane including the length direction and lamination direction. FIG. 1 is a flow diagram showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers), the method including a plating removal step.

First Embodiment
1. Separation and Recovery Method A method for separating and recovering rare earth components and metal components (first metal components and second metal components) from post-sintering waste of multilayer ceramic capacitors (sintering for fired electrode layers) according to a first embodiment of the present invention will be described.

FIG. 1 is a flow diagram showing a method for separating and recovering rare earth components and metal components from post-sintering waste (sintering for fired electrode layers) of multilayer ceramic capacitors according to a first embodiment of the present invention. In the separation and recovery method according to the first embodiment of the present invention, post-sintering waste (sintering for fired electrode layers) of multilayer ceramic capacitors is used as the starting point for separation and recovery. The post-sintering waste will now be described.

(1) Post-Firing Waste Before describing the post-firing waste, a multilayer ceramic capacitor manufactured in a manufacturing process for a multilayer ceramic capacitor and the manufacturing process for the multilayer ceramic capacitor will be described below.

(1-1) Multilayer Ceramic Capacitor Fig. 2 is an external perspective view showing an example of a multilayer ceramic capacitor according to a first embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Here, a two-terminal multilayer ceramic capacitor will be described as an example of the multilayer ceramic capacitor 10.

As shown in Figures 2 and 3, the multilayer ceramic capacitor 10 includes, for example, a rectangular parallelepiped laminate 12 and external electrodes 30 arranged on both ends of the laminate 12.

The laminate 12 has a plurality of stacked ceramic layers 14 and a plurality of internal electrode layers 16 stacked on the ceramic layers 14. Furthermore, the laminate 12 has a first main surface 12a and a second main surface 12b that face each other in a height direction (stacking direction) x, a first side surface 12c and a second side surface 12d that face each other in a width direction y perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f that face each other in a length direction z perpendicular to the height direction x and the width direction y. The ceramic layers 14 and the internal electrode layers 16 are stacked in the height direction x.

The first internal electrode layer 16a and the second internal electrode layer 16b can be made of, for example, a conductive material containing a magnetic base metal, and the magnetic base metal can be a simple metal or an alloy. Examples of magnetic base metals include Ni and Fe. Note that, here, a metal that has a higher ionization tendency than hydrogen is referred to as a base metal.

The ceramic layer 14 has an aggregate of a plurality of ceramic particles (each BT in FIG. 5 described later, also called a ceramic sintered body). Each ceramic particle can be formed, for example, by a dielectric material as the ceramic material. As such a dielectric material, for example, a dielectric ceramic having a perovskite structure with a perovskite type compound containing a component such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , or CaZrO ₃ as the main component can be used. When the dielectric material is contained as the main component, a rare earth component is added to the dielectric material as an additive according to the desired characteristics of the laminate 12. As the rare earth component to be added, for example, at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu can be mentioned. The above-mentioned dielectric material may be used with the addition of a minor component, such as a Mn compound, an Fe compound, a Cr compound, a Co compound, or a Ni compound, in a content less than that of the main component. At least one of Si, Mg, Ba, and Mn may be added as an additional additive to the above-mentioned main component. However, since these minor components and additives may cause a deterioration in the quality of the rare earth components during the separation and recovery of the rare earth components, these minor components and additives may be omitted.

As shown in Figures 2 and 3, external electrodes 30 are arranged on the first end face 12e side and the second end face 12f side of the laminate 12.

The external electrode 30 has a first external electrode 30a and a second external electrode 30b. The first external electrode 30a is connected to the first internal electrode layer 16a and is disposed on at least the surface of the first end face 12e. The second external electrode 30b is connected to the second internal electrode layer 16b and is disposed on at least the surface of the second end face 12f.

The external electrode 30 includes a baked electrode layer 32. The first external electrode 30a includes a first baked electrode layer 32a. The second external electrode 30b includes a second baked electrode layer 32b. In this embodiment, the baked electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10. In other words, the baked electrode layer 32 is the outermost layer of the layers disposed on the laminate 12.

The baked electrode layer 32 may be formed from a baked layer containing a glass component and a second metal component which is a non-magnetic precious metal. The second metal component of the baked layer includes at least one selected from Cu, Ag, etc. The glass component of the baked layer includes an oxide containing at least one element selected from B, Si, Ba, Mg, Al, Li, etc. Here, a metal that has a lower ionization tendency than hydrogen is referred to as a precious metal.

(1-2) Method for Manufacturing the Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 10 will be described.

(Step 1) First, a dielectric sheet for the ceramic layer and a conductive paste for the internal electrode layer are prepared. The dielectric sheet for the ceramic layer is formed from a dielectric slurry containing, but not limited to, _BaTiO3 as a main component and Dy as an additive. The conductive paste for the internal electrode layer is formed from, but not limited to, Ni as a main component. The dielectric sheet and the conductive paste for the internal electrode layer include a binder and a solvent. The binder and the solvent are composed of a resin component, and the resin component can be, for example, various known thermosetting resins such as epoxy resin, phenoxy resin, phenol resin, urethane resin, and polyimide resin.

(Step 2) Then, a conductive paste for the internal electrode layers is printed in a predetermined pattern on the dielectric sheet, for example by screen printing or gravure printing. This prepares a dielectric sheet on which the pattern of the first internal electrode layer is formed, and a dielectric sheet on which the pattern of the second internal electrode layer is formed.

In addition, with regard to the dielectric sheets, outer layer dielectric sheets that do not have the internal electrode layer pattern printed on them are also prepared.

A predetermined number of dielectric sheets for the outer layers, on which the pattern of the internal electrode layer is not printed, are stacked. A dielectric sheet on which the pattern of the first internal electrode layer is printed, and a dielectric sheet on which the pattern of the second internal electrode layer is printed are stacked in order on top of the dielectric sheets to form an inner layer portion. A predetermined number of dielectric sheets for the outer layers, on which the pattern of the internal electrode layer is not printed, are stacked on top of the inner layer portion. This forms a laminated sheet having an inner layer portion and an outer layer portion. The dielectric sheets are sometimes referred to as the ceramic layers when unfired, that is, the ceramic layers before the laminated chip is fired. The pattern of the internal electrode layers is sometimes referred to as the internal electrode layers when unfired, that is, the internal electrode layers before the laminated chip is fired.

(Step 3) Next, the laminated sheet is pressed in the stacking direction using a means such as a hydrostatic press to produce a laminated block.

(Step 4) The laminated block is then cut to a predetermined size to cut out the laminated chip. FIG. 4 is a schematic diagram showing the state of the unfired ceramic layers and the unfired internal electrode layers in a cross section parallel to a plane including the length direction and the lamination direction in the laminated chip. FIG. 4 shows a cross section of the laminated chip on which the external electrodes 30 have not yet been formed. The laminated chip in FIG. 4 is in a state prior to degreasing (step 5) and firing of the laminated chip (step 6). However, the resin component contained in the laminated chip is not shown. As shown in FIG. 4, the laminated chip is formed by alternately stacking the unfired internal electrode layers 16_U and the unfired ceramic layers 14_U.

The laminated chip as a whole contains a first metal powder (Ni_P in FIG. 4), ceramic powders (BT ₁ _P, BT ₂ _P in FIG. 4), rare earth powder (Dy_P in FIG. 4), and a resin component. The first metal powder mainly constitutes the internal electrode layer 16_U when unsintered. The ceramic powder mainly constitutes the ceramic layer 14_U when unsintered.

The first metal powder is, for example, an aggregate of first metal atoms, which is the first metal component. As described above, the first metal powder can be made of a conductive material containing a magnetic base metal, and the magnetic base metal can be either an elemental metal or an alloy. Examples of magnetic base metals include Ni and Fe.

The ceramic powder is an aggregate of dielectric materials. As described above, examples of the dielectric materials include BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , and CaZrO ₃ . The ceramic powder includes a first ceramic powder and a second ceramic powder. The second ceramic powder has a smaller particle size than the first ceramic powder.

Rare earth powder is an aggregate of rare earth atoms, which are rare earth components. As mentioned above, the rare earth atoms can be at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

The resin components are binders and solvents for producing conductive pastes for the dielectric sheets and internal electrode layers. The binders and solvents are composed of resin components, and various known thermosetting resins such as epoxy resins, phenoxy resins, phenolic resins, urethane resins, and polyimide resins can be used as the resin components.

The state of the powder in the laminated chip will be further explained using FIG. 4. The schematic diagram of FIG. 4 shows the state of various powders contained in the laminated chip before the degreasing in (step 5) and the firing of the laminated chip in (step 6). In FIG. 4, the resin component is omitted. As shown in FIG. 4, in this embodiment, the ceramic layer 14_U when unfired is mainly composed of the first ceramic powder (BT ₁ _P in FIG. 4). In the ceramic layer 14_U when unfired, the first ceramic powder and the rare earth powder (Dy_P in FIG. 4) are at least partially attached to each other. As shown in the example of FIG. 4, the rare earth powder is mainly attached to the surface of the first ceramic powder, and basically, the rare earth powder does not penetrate into the inside of the first ceramic powder and is not chemically bonded. In this embodiment, the internal electrode layer 16_U when unfired is mainly composed of the first metal powder (Ni_P in FIG. 4). In the unfired internal electrode layer 16_U, the first metal powder and the second ceramic powder (BT ₂ _P in FIG. 4) are at least partially attached to each other. As shown in the example of FIG. 4, the second ceramic powder is mainly attached to the surface of the first metal powder, and the second ceramic powder is not basically chemically bonded to the inside of the first metal powder. The meaning of "attached" may include that the powders such as the first metal powder, the ceramic powder, and the rare earth powder are partially chemically bonded to each other. The chemical bond is a bond in which a plurality of atoms are attracted to each other by positive and negative charges, such as an ionic bond, a covalent bond, or a metallic bond.

(Step 5)
Next, the resin components in the laminated chip are removed. Hereinafter, the removal of the resin components in step 5 is a degreasing step in the manufacturing process. The degreasing temperature in the degreasing step 5 is, for example, higher than 800° C. and equal to or lower than 1000° C.

(Step 6) Next, the laminated chip is fired to produce the laminate 12. The firing temperature for the laminated chip depends on the materials of the ceramic layers and internal electrode layers, which are dielectrics, but is preferably higher than 1000°C and lower than 1400°C, for example. Steps 1 to 6 are the laminate formation process. Note that the firing in step 6 is sometimes called firing the laminated chip. This firing turns the unfired laminated chip into the laminate 12. Furthermore, the unfired internal electrode layer 16_U and the unfired ceramic layer 14_U are fired to become the internal electrode layer 16 and the ceramic layer 14.

(Step 7) Next, a baked electrode layer paste containing a plurality of second metal powders (e.g., Cu powder) is applied to the first and second end faces 12e, 12f of the laminate 12 and fired to form a baked electrode layer 32, which is an external electrode 30. The second metal powder is, for example, an aggregate of second metal atoms, which is a second metal component. Each second metal powder in the baked electrode layer paste is dispersed alone in the baked electrode layer paste, or is dispersed by adhering to other powders including other second metal powders. In other words, in the baked electrode layer paste, each second metal powder is not chemically bonded to other second metal powders or powders such as other additives. Then, the baked electrode layer paste is fired, so that the second metal powders are in a sintered state. The firing temperature of the baked electrode layer paste is preferably 700°C or higher and 900°C or lower. The firing in step 7 may be referred to as firing for the baked electrode layer.

Next, the state of each layer of the multilayer ceramic capacitor 10 after firing for the fired electrode layers in (step 7) will be described. Figure 5 is an enlarged view of the α portion of Figure 3, and is a schematic diagram showing the state of each layer after firing for the fired electrode layers. Figure 6 is a partial enlarged view of the ceramic layers in Figure 5. After firing for the fired electrode layers, the multilayer ceramic capacitor 10 is in a sintered state with each part, such as the ceramic layer 14, the internal electrode layer 16, and the external electrode 30.

In the ceramic layer 14, the ceramic powder (BT ₁ _P, BT ₂ _P in FIG. 4 ) is fired to become ceramic particles BT (BT in FIG. 5 ) in a sintered state as shown in FIG. 5 . The ceramic powder (BT ₁ _P, BT ₂ _P in FIG. 4 ) is fired, for example, in the stacked chip (step 6 ), to form the fired ceramic particles BT. The ceramic particles BT in a sintered state may be called a ceramic sintered body BT. For example, the ceramic powder is fired to develop the contact between the ceramic particles from point contact to surface contact. This causes the chemical bonding between the ceramic powders to progress, forming integrated ceramic particles BT (ceramic sintered body BT). The ceramic particles BT may be formed by partially chemically bonding the ceramic powder with the rare earth powder. In the example of FIG. 5 , the ceramic layer 14 includes an aggregate of a plurality of ceramic particles BT. Most of the first ceramic powder (BT ₁ _P in FIG. 4 ) forms the ceramic layer 14, for example, by firing the laminated chip in (step 6). Most of the second ceramic powder (BT ₁ _P in FIG. 4 ) adhering to the first metal powder (Ni_P in FIG. 4 ) forms the ceramic layer 14, for example, by firing the laminated chip in (step 6). At this time, most of the second ceramic powder (BT ₁ _P in FIG. 4 ) is pushed out from the fired internal electrode layer 16 without basically bonding with the fired internal electrode layer 16, and is fired together with the first ceramic powder to form the ceramic layer 14.

Further explaining the ceramic layer 14, each ceramic particle BT is formed by a core shell 40 shown in FIG. 6. The core shell 40 has a core portion 42 including a central portion of the core shell 40, and a shell portion 44 covering the surface of the core portion 42. The core portion 42 is mainly formed of a ceramic material. The shell portion 44 is formed by incorporating, for example, a rare earth component, which is an additive, into the ceramic material. The shell portion 44 may also incorporate other subcomponents such as Mn compounds. A grain boundary 50 exists at the boundary between the ceramic particles BT. The grain boundary 50 contains a rare earth inclusion. The rare earth inclusion contains the rare earth component in the form of, for example, an oxide. An example of the oxide of the rare earth component is dysprosium oxide (Dy ₂ O ₃ ). The rare earth inclusion may also contain, for example, silicon dioxide (SiO ₂ ), manganese dioxide (MnO ₂ ), etc. In the above, it has been described that each ceramic particle BT has a core-shell structure. However, each ceramic particle BT may have a structure in which the rare earth component or the like is incorporated up to the center of the ceramic particle BT. Moreover, ceramic particles BT having such a structure and ceramic particles BT having a core-shell structure may be mixed in the ceramic layer 14.

The internal electrode layer 16 is formed by firing the first metal powder (Ni_P in FIG. 4) to form the first metal particles (Ni in FIG. 5) in a sintered state as shown in FIG. 5. The first metal powder (Ni_P in FIG. 4) forms the fired internal electrode layer 16, for example, by firing the stacked chip in (step 6). In FIG. 5, the Ni powder, which is the first metal powder, is sintered to form Ni particles (first metal particles). The first metal particles in a sintered state may also be called a first metal sintered body. For example, the first metal powder is heated by firing, and the contact between the first metal powder particles develops from point contact to surface contact. As a result, the bonding between the first metal powder particles progresses to form integrated first metal particles (first metal sintered body). In the example of FIG. 5, the internal electrode layer 16 includes an aggregate of multiple first metal particles.

The baked electrode layer 32 (external electrode 30) is formed by firing the second metal powder (e.g., Cu powder) for the baked electrode layer, and is turned into second metal particles (Cu in FIG. 5) in a sintered state as shown in FIG. 5. In FIG. 5, the Cu powder, which is the second metal powder, is sintered into Cu particles (second metal particles). The second metal particles in a sintered state may be called a second metal sintered body. For example, the second metal powder is heated by firing for the baked electrode layer, and the contact between the second metal powder develops from point contact to surface contact. As a result, the bonding between the second metal powder progresses to form integrated second metal particles (second metal sintered body). In the example of FIG. 5, the baked electrode layer 32 includes an aggregate of multiple second metal particles.

The multilayer ceramic capacitor 10 is manufactured through the above-mentioned manufacturing process.

In this embodiment, the post-firing waste is waste after the firing for the fired electrode layer in (step 7) when the multilayer ceramic capacitor 10 is manufactured by the manufacturing method for the multilayer ceramic capacitor 10 described above.

(2) Flow of the separation and recovery method The flow of the separation and recovery method according to the first embodiment of the present invention will be described with reference to Fig. 1. The separation and recovery method in Fig. 1 includes a common separation and recovery route, a rare earth component separation and recovery route, a first metal component separation and recovery route, and a second metal component separation and recovery route. The rare earth component separation and recovery route and the first metal component separation and recovery route branch off from the common separation and recovery route. The second metal component separation and recovery route branches off from the rare earth component separation and recovery route.

The common separation and recovery route includes, for example, preparation of post-calcination waste in step (A), pulverization in step (B), and magnetic separation in step (C). After magnetic separation in step (C), the process branches into a rare earth component separation and recovery route and a first metal component separation and recovery route. The rare earth component separation and recovery route can include, for example, dissolution of the second separated material in step (D), and can further include filtration in step (F), and neutralization in step (G). After filtration in step (F), the second metal component separation and recovery route branches off from the rare earth component separation and recovery route. The second metal component separation and recovery route can include, for example, dissolution of the undissolved material in step (E), and can further include filtration in step (H). The first metal component separation and recovery route can include, for example, dissolution of the first separated material in step (I), and can further include filtration in step (J).

(Step (A): Preparation of post-firing waste)
In step (A), post-sintering waste of a multilayer ceramic capacitor (sintering for sintered electrode layers) is prepared. The post-sintering waste is as described above. The post-sintering waste includes a laminate 12 including ceramic layers 14 and internal electrode layers 16, and a sintered electrode layer 32. The ceramic layers 14, the internal electrode layers 16, and the sintered electrode layer 32 are in a sintered state.

(Process (B): Refinement)
In step (B), the fired waste is pulverized. For example, but not limited to, the fired waste is pulverized by crushing. The pulverization is performed, but not limited to, for example, by a method of applying a pulverizing force by vibration to the object using a vibration mill or the like, a method of grinding the object, a method of applying a pulverizing force by impact to the object, and the like. It is preferable to pulverize the fired waste to an extent that it is easy to separate in the magnetic separation in step (C) described later. By pulverizing the fired waste, it is possible to obtain a ceramic pulverized product in which the sintered ceramic layer 14 is pulverized, a rare earth-containing material in the sintered state, a first metal pulverized product in which the sintered internal electrode layer 16 is pulverized, and a second metal pulverized product in which the sintered baked electrode layer 32 is pulverized. The ceramic pulverized product includes, for example, a ceramic material such as BaTiO ₃ , CaTiO ₃ , SrTiO ₃ , or CaZrO ₃ . The rare earth-containing material _may include, for example, dysprosium oxide ( _Dy2O3 ), and may also include, for example, silicon dioxide ( _SiO2 ), manganese dioxide ( _MnO2 ), etc. The first finely divided metal material may include, for example, a first metal component such as Ni and Fe. The second finely divided metal material may include, for example, a second metal component such as Cu. The average particle size of the post-calcination waste after being finely divided is not limited. The average particle size may be determined, for example, by using a sieve.

(Step (C): Magnetic separation)
In the magnetic separation of step (C), the post-calcination waste after being pulverized in step (B) is magnetically separated using a magnet. That is, the post-calcination waste is separated into a first separated matter and a second separated matter by magnetic separation and recovered.

The first separated material contains a first metal microparticle (Ni in FIG. 1) and a ceramic microparticle (BT in FIG. 1). The first metal microparticle contains a first metal component, which is a magnetic base metal. On the other hand, the ceramic microparticle does not have magnetic properties. The first separated material is separated as a magnetic material by magnetic separation. Specifically, in the first separated material, when the magnetic first metal microparticle is separated as a magnetic material, the non-magnetic ceramic microparticle is entangled with this first metal microparticle.

The second separated material includes a second metal fine particle (Cu in FIG. 1), a rare earth-containing material ( _Dy2O3 in FIG. 1), and a ceramic fine particle (BT in FIG. 1). The second metal fine particle includes a second metal component that is a noble metal having no magnetism. Furthermore, the rare earth-containing material _and the ceramic fine particle have no magnetism. Therefore, the second metal fine particle, the rare earth-containing material, and the ceramic fine particle are separated as non-magnetic materials by magnetic separation.

Therefore, by this magnetic separation, the second separated material is removed from the post-sintering waste, and the first separated material containing the first metal fine particles can be separated and recovered as the first metal component. For example, the first metal fine particles are fine particles of sintered Ni (first metal component) that constitutes the internal electrode layer 16. Note that in the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first separated material containing the first metal fine particles as the first metal component.

The first metal component includes the first metal atom itself, a first metal component compound which is a reaction product of the first metal atom chemically reacting with other atoms, a solution of the first metal atom, a solution of the first metal component compound, and the like. The state of the first metal component may be any of a liquid state, a solid state, and a mixed state of liquid and solid. The first metal component may be any of an amorphous state, a crystalline state, and a mixed state of amorphous and crystalline.

In other words, this magnetic separation makes it possible to separate and recover the second metal fine particles and rare earth-containing material from the post-sintering waste after removing the first separated material.

In addition, during magnetic separation, it is preferable to mix and disperse the post-calcination waste after it has been pulverized in step (B) with an aqueous solvent such as water to create a mixed state, and then separate it using a magnet.

When the finely divided calcined waste is mixed with an aqueous solvent to form a mixed state, i.e., a slurry state, the ceramic fine particles, rare earth-containing material, first metal fine particles, and second metal fine particles contained in the finely divided calcined waste can be dispersed. Therefore, in step (C), the first separated material and the second separated material can be easily separated using a magnet. When the finely divided calcined waste is in a dry state, the first separated material and the second separated material tend to be less dispersed than when in a slurry state. Therefore, for example, when the first separated material is attracted to a magnet, the second separated material is caught in the first separated material and attracted to the magnet, making it difficult to separate the first separated material and the second separated material.

(Step (D): Dissolution of the second separated product)
In step (D), the second separated product separated and recovered in step (C) is dissolved in a mineral acid having no oxidizing power. This allows a rare earth component-containing solution to be generated in which the rare earth components in the rare earth-containing material contained in the second separated product are dissolved. Thus, the rare earth component-containing solution can be separated and recovered as a rare earth component. At this time, the ceramic fine particles and the second metal fine particles in the second separated product are precipitated. The ceramic fine particles react with the mineral acid having no oxidizing power to become undissolved and precipitate. In addition, the second metal fine particles such as Cu have a smaller ionization tendency than the hydrogen ions contained in the mineral acid having no oxidizing power, and therefore do not dissolve in the mineral acid having no oxidizing power. The mineral acid having no oxidizing power is, for example, at least one selected from the group including dilute sulfuric acid and hydrochloric acid.

As described above, the rare earth components are separated and recovered as a rare earth component-containing solution. In the present invention, the separation and recovery of rare earth components includes not only the separation and recovery of the rare earth components themselves, but also the separation and recovery of the rare earth component-containing solution as rare earth components. In other words, the rare earth components include rare earth atoms themselves, rare earth component compounds which are reaction products in which rare earth atoms have chemically reacted with other atoms, solutions of rare earth atoms, solutions of rare earth component compounds, etc. The state of the rare earth components may be any of a liquid state, a solid state, or a mixed state of liquid and solid. The rare earth components may be any of an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline.

In step (D), it is preferable to adjust the pH of the rare earth component-containing solution to 1.5 or more and 2.5 or less by adding a mineral acid that has no oxidizing power.

In step (D), by adjusting the rare earth component-containing solution to a pH of 1.5 or more and 2.5 or less using a mineral acid with no oxidizing power, it is possible to dissolve mainly the rare earth components in the rare earth-containing material in the mineral acid with no oxidizing power. Furthermore, if the pH is adjusted to a stronger acid than the above range, ceramic fine particles and the like may dissolve in the mineral acid with no oxidizing power, so it is preferable to adjust the pH to within the above range. More preferably, the rare earth component-containing solution is adjusted to a pH of 2 by adding a mineral acid with no oxidizing power.

When the post-calcination waste, which is in a slurry state, is magnetically separated in step (C), the separated second separated material is in a slurry state with a pH of about 7. By adding a mineral acid with no oxidizing power to this slurry, it is also possible to produce a rare earth component-containing solution adjusted to a pH of 1.5 or more and 2.5 or less. However, the second separated material after magnetic separation does not need to be in a slurry state and may be in a dry state.

As the mineral acid having no oxidizing power, when the ceramic fine particles contained in the second separated product are, for example, BaTiO ₃ , dilute sulfuric acid is preferably used. When dilute sulfuric acid is used, insoluble BaSO ₄ is formed on the surface of the ceramic fine particles, which are BaTiO ₃ , so that the ceramic fine particles can be precipitated. In addition, the second metal fine particles, such as Cu, do not dissolve in the mineral acid having no oxidizing power because they have a smaller ionization tendency than the hydrogen ions contained in the mineral acid having no oxidizing power. On the other hand, rare earth powder can be dissolved in dilute sulfuric acid. Specifically, for example, when the second separated product mainly containing the second metal fine particles, the rare earth-containing material such as Dy ₂ O ₃ , and the ceramic fine particles, which are BaTiO _3, is dissolved in dilute sulfuric acid, BaTiO ₃ precipitates and Cu does not dissolve. On the other hand, a dysprosium sulfate (Dy ₂ (SO ₄ ) ₃ ) solution in which Dy in the rare earth-containing material is dissolved in dilute sulfuric acid is generated as a rare earth component-containing solution.

As described above, hydrochloric acid or the like can be used as the mineral acid having no oxidizing power. However, for example, when hydrochloric acid is used as the mineral acid having no oxidizing power, soluble BaCl ₂ is formed on the surface of the ceramic fine particles, BaTiO _3. Therefore, it is preferable to accurately adjust the pH of hydrochloric acid or the like so as to precipitate the ceramic fine particles and dissolve the rare earth-containing material while not dissolving the second metal fine particles.

(Step (F): Filtration)
In step (F), the rare earth component-containing solution containing the precipitated ceramic fine particles and the undissolved second metal fine particles produced in step (D) is filtered to separate the undissolved ceramic fine particles and the second metal fine particles from the rare earth component-containing solution. This solid-liquid separation allows the rare earth component-containing solution from which the undissolved ceramic fine particles and the second metal fine particles have been removed to be separated and recovered as rare earth components.

For example, in step (D), _BaTiO3 is precipitated, and second metal fine particles such as Cu are not dissolved, and a dysprosium sulfate (Dy2( _SO4 ) ₃ ) solution in which Dy is dissolved in dilute sulfuric acid is generated as a rare earth component- _containing solution. In this case, the dysprosium sulfate solution from which _BaTiO3 and Cu have been removed can be separated and recovered as rare earth components by the filtration in step (F).

Filtration can be performed using filter paper (filter cloth). It is preferable that the mesh size of the filter paper (filter cloth) is such that the undissolved ceramic microparticles and the second metal microparticles do not pass through the filter paper (filter cloth).

It is sufficient that the rare earth component-containing solution containing the undissolved ceramic fine particles and the second metal fine particles produced in step (D) can be separated into solid and liquid, and the solid-liquid separation is not limited to filtration, but can be performed by any known method appropriately selected, such as decantation or centrifugation. Filtration is more preferable.

(Step (G): Neutralization)
In step (G), the rare earth component-containing solution obtained in step (F) is neutralized to precipitate and recover the rare earth component. The precipitated rare earth component is separated and recovered, for example, by filtering the neutralized rare earth component-containing solution. At this time, the rare earth component is separated and recovered as a rare earth component compound (e.g., Dy(OH) ₃ , etc.) by neutralization. In the present invention, the separation and recovery of the rare earth component includes not only the separation and recovery of the rare earth component itself, but also the separation and recovery of the rare earth component compound, which is a reaction product of the rare earth component chemically reacted, as the rare earth component.

An alkali is used for neutralization. Examples of alkalis include sodium hydroxide and potassium hydroxide. When the redox potential changes, the pH range in which rare earth components precipitate can change, but by using these as alkalis, the pH range in which rare earth components precipitate can be stabilized.

In addition, in the neutralization step (G), the rare earth components are recovered by adjusting the pH of the rare earth component-containing solution to between pH 6 and pH 9. This allows the precipitate resulting from the neutralization reaction to be efficiently separated and recovered as rare earth components. More preferably, the rare earth component-containing solution is adjusted to pH 8 by adding an alkali.

For example, in the filtration of step (F), when a dysprosium sulfate solution from which _BaTiO3 , Cu, etc. have been removed is obtained, dysprosium hydroxide (Dy(OH) ₃ ) is obtained as a rare earth component compound by neutralization with sodium hydroxide. That is, since the dysprosium sulfate solution is acidic, the rare earth component dysprosium can be precipitated as dysprosium hydroxide (Dy(OH) ₃ ) by neutralizing it with an alkali, and separated and recovered. Here, dysprosium hydroxide (Dy(OH) ₃ ) can be separated and recovered by filtering the solution obtained by neutralizing the dysprosium sulfate solution with an alkali. In addition to filtration, known methods such as decantation and centrifugation can be used.

In addition, there are metal components (so-called contaminants) that are not separated as the first separated product in the magnetic separation in step (C) and are caught in the second separated product. Therefore, the rare earth component-containing solution produced in the dissolution of the second separated product in step (D) may contain metal components that are contaminants. These metal components are, for example, Ti, Mn, Ni, etc. Then, in step (G), an alkali is added to the rare earth component-containing solution to adjust the pH to, for example, from 3 to 5, preferably about pH 4, so that Ti, Mn, etc. can be separated and recovered. In this case, Ti precipitates as, for example, Ti(OH) ₄ , and Mn precipitates as, for example, Mn(OH) _2. Therefore, the rare earth component-containing solution adjusted to about pH 4 is filtered to recover Ti(OH) ₄ , Mn(OH) ₂ , etc.

Then, the rare earth components are separated and recovered by adding an alkali to the solution containing the rare earth components from which Ti, Mn, etc. have been separated and adjusted to a pH of 6 or more and 9 or less, preferably about pH 8, as described above.

Thereafter, Ni and the like can be separated and recovered by adding an alkali to the solution from which Ti, Mn, rare earth components, etc. have been separated, for example, to a pH of more than 9 to a pH of 11 or less, preferably about pH 10. In this case, Ni precipitates as, for example, Ni(OH) ₂ . The solution adjusted to about pH 10 is filtered to recover Ni(OH) ₂ and the like.

By repeating this step-by-step neutralization and filtration process, it is possible to separate and recover the various components (contaminants, rare earth components, etc.) contained in the rare earth component-containing solution.

Furthermore, in the stepwise neutralization of the rare earth component-containing solution as described above, the rare earth component-containing solution is neutralized to a pH of 3 or more and a pH of 5 or less, preferably about pH 4, before the rare earth components are separated. Therefore, it is possible to first remove contaminants such as Ti and Mn from the rare earth component-containing solution. Since contaminants such as Ti and Mn have been removed from the rare earth component-containing solution in this way, it is possible to further facilitate separation of the rare earth components using the rare earth component-containing solution from which these contaminants have been removed.

(Step (E): Dissolving undissolved matter)
In step (E), the ceramic fine particles and the second metal fine particles taken out by filtration in step (F) are dissolved in ammonia water. This produces a second metal solution in which the second metal component contained in the second metal fine particles is dissolved. Thus, the second metal solution can be separated and recovered as the second metal component. At this time, the ceramic fine particles are precipitated.

Specifically, a second metal fine particle containing a second metal component such as Cu and a ceramic fine particle of _BaTiO3 are dissolved in ammonia water, thereby obtaining a second metal solution containing an ammine copper complex such as [Cu( _NH3 ) ₄ ] ²⁺ . _BaTiO3 precipitates in the second metal solution.

As described above, the second metal component is separated and recovered as a second metal solution. In the present invention, the separation and recovery of the second metal component includes not only the separation and recovery of the second metal component itself, but also the separation and recovery of the second metal component solution as the second metal component. Here, the second metal component includes the second metal component itself, a second metal component compound which is a reaction product of the second metal component chemically reacting with other atoms, etc., a solution of the second metal component, a solution of the second metal component compound, etc. The state of the second metal component may be any of a liquid state, a solid state, and a mixed state of liquid and solid. The second metal component may be any of an amorphous state, a crystalline state, and a mixed state of amorphous and crystalline.

In step (E), it is preferable to adjust the second metal solution to a pH of 9 or more and a pH of 10 or less by adding ammonia water. In this way, by adjusting the second metal solution to a pH of 9 or more and a pH of 10 or less in step (E), the second metal solution can be efficiently separated and recovered as the second metal component. More preferably, the second metal solution is adjusted to a pH of 9.5 by adding ammonia water.

In addition, when the undissolved ceramic fine particles and the second metal fine particles taken out in step (F) are dissolved in ammonia water, it is preferable to add an ammonium salt such as ammonium sulfate to the ammonia water. Here, the ammonia water is a source of ammonia for forming the second metal component such as Cu as an ammine complex such as a copper ammine complex. In addition, the ammonium salt provides a counter ion to the ammine complex such as the copper ammine complex. For example, an ammonium salt such as ammonium sulfate supplies SO ₄ ^2- as a counter ion to the copper ammine complex which is [Cu(NH ₃ ) ₄ ] ²⁺ . And even if the concentration of ammonia decreases, it forms a salt such as CuSO ₄ to suppress the precipitation of Cu ions.

(Step (H): Filtration)
In step (H), the second metal solution containing the precipitated ceramic fine particles produced in step (E) is filtered to separate the precipitated ceramic fine particles from the second metal solution. By this solid-liquid separation, the second metal solution from which the precipitated ceramic fine particles have been removed can be separated and recovered as a second metal component from the second metal solution containing the precipitated ceramic fine particles.

For example, in step (E), a second metal solution is generated in which a second metal component such as Cu is dissolved in ammonia water while _BaTiO3 is precipitated. The second metal solution contains a copper ammine complex such as [Cu( _NH3 ) ₄ ] ²⁺ . In this case, the second metal solution containing the copper ammine complex from which _BaTiO3 has been removed can be separated and recovered as the second metal component by filtration in step (H).

Filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic fine particles do not pass through the filter paper (filter cloth). In addition, the solid-liquid separation of the second metal solution containing the precipitated ceramic fine particles produced in step (E) need only be performed, and the solid-liquid separation is not limited to filtration, and can be performed by any known method appropriately selected, such as decantation or centrifugation. Filtration is more preferable.

(Step (I): Dissolution of the first separated product)
In step (I), the first separated product separated and recovered in step (C) is dissolved in a mineral acid. The first separated product includes a first metal fine product and a ceramic fine product. By dissolving the first separated product in a mineral acid, the ceramic fine product contained in the first separated product is precipitated as an undissolved product, and a first metal solution in which the first metal fine product in the first separated product is dissolved is generated. At this time, the first metal component contained in the first metal fine product is separated and recovered as a first metal solution. In the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first metal solution as the first metal component. The mineral acid is, for example, at least one selected from the group including sulfuric acid, nitric acid, and hydrochloric acid. The mineral acid may be either a mineral acid that does not have oxidizing power or a mineral acid that has oxidizing power. In addition, in the present embodiment, when simply saying mineral acid, it is meant to include both a mineral acid that does not have oxidizing power and a mineral acid that has oxidizing power.

In step (I), it is preferable to adjust the pH of the first metal solution to 1.5 or more and 2.5 or less by adding a mineral acid.

In step (I), the first metal solution is adjusted to a pH of 1.5 or more and 2.5 or less using a mineral acid, so that the first metal component in the first metal fine particles can be dissolved in the mineral acid. In addition, if the pH is adjusted to a stronger acid than the above range, the ceramic fine particles and the like may dissolve in the mineral acid, so it is preferable to adjust the pH to within the above range. More preferably, the first metal solution is adjusted to a pH of 2 by adding a mineral acid.

When the post-calcination waste in a slurry state is magnetically separated in step (C), the separated first separated material is in a slurry state with a pH of about 7. By adding a mineral acid to this slurry, a first metal solution adjusted to a pH of 1.5 or more and 2.5 or less can be produced. However, the first separated material after magnetic separation does not need to be in a slurry state and may be in a dry state.

As the mineral acid, when the ceramic fine particles contained in the first separation product are, for example, BaTiO ₃ , it is preferable to use sulfuric acid. When sulfuric acid is used, insoluble BaSO ₄ is formed on the surface of the ceramic fine particles, which are BaTiO ₃ , so that the ceramic fine particles can be precipitated. On the other hand, the first metal fine particles, such as Ni, can be dissolved in sulfuric acid. Specifically, for example, by dissolving the first separation product, which mainly contains the first metal fine particles, Ni and the ceramic fine particles, which are BaTiO ₃ , in sulfuric acid, BaTiO ₃ is precipitated, and a nickel sulfate (NiSO ₄ ) solution in which Ni is dissolved in sulfuric acid is generated as the first metal solution.

As described above, hydrochloric acid or the like can be used as the mineral acid other than sulfuric acid. However, for example, when hydrochloric acid is used as the mineral acid, soluble _BaCl2 is formed on the surface of _BaTiO3 , which is the ceramic fine particle. Therefore, it is preferable to precisely adjust the pH of hydrochloric acid or the like so as to precipitate the ceramic fine particle and dissolve the first metal fine particle.

(Step (J): Filtration)
In step (J), the first metal solution containing the precipitated ceramic fine particles produced in step (I) is filtered to separate the precipitated ceramic fine particles from the first metal solution. By this solid-liquid separation, the first metal solution from which the precipitated ceramic fine particles have been removed can be separated and recovered as a first metal component from the first metal solution containing the precipitated ceramic fine particles.

For example, in step (I), _BaTiO3 is precipitated and a nickel sulfate ( _NiSO4 ) solution in which Ni is dissolved in sulfuric acid is generated as the first metal solution. In this case, the nickel sulfate solution from which _BaTiO3 has been removed can be obtained by filtration.

Filtration can be performed using filter paper (filter cloth). The mesh size of the filter paper (filter cloth) is preferably such that the precipitated ceramic fine particles do not pass through the filter paper (filter cloth). In addition, the solid-liquid separation of the first metal solution containing the precipitated ceramic fine particles produced in step (I) need only be performed, and is not limited to solid-liquid separation by filtration, and solid-liquid separation can be performed by an appropriate selection from known methods such as decantation and centrifugation. Filtration is more preferable.

In addition, instead of or together with the filtration in step (J), treatments such as crystallization and neutralization can be performed. The first metal solution obtained by the above-mentioned filtration can be treated to separate and recover the first metal component, for example, as a first metal component compound (e.g., _NiSO4 , _NiCl2 , etc.). In the present invention, the separation and recovery of the first metal component includes not only the separation and recovery of the first metal component itself, but also the separation and recovery of the first metal component compound, which is a reaction product of the chemical reaction of the first metal component, as the first metal component.

(3) Effects and Effects According to the above separation and recovery method, the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 can be separated and recovered from the fired waste of the multilayer ceramic capacitor. The details are explained below.

The inventors of the present application have considered the effective use of various components contained in waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers). In the waste after firing, various components are in a sintered state due to the firing process. For example, the internal electrode layer is formed including first metal particles (first metal sintered body) obtained by sintering a first metal powder such as Ni by firing. Also, for example, the ceramic layer is formed including ceramic particles (ceramic sintered body) obtained by sintering a ceramic powder such as BaTiO ₃ by firing. Also, for example, the external electrode is formed including second metal particles (second metal sintered body) obtained by sintering a second metal powder such as Cu by firing. Thus, even when each part of the multilayer ceramic capacitor is in a sintered state, it has been found that various components contained in the multilayer ceramic capacitor can be separated and recovered by devising a separation and recovery method.

Furthermore, by pulverizing the post-sintered waste in step (B), it is possible to obtain ceramic microparticles, rare earth-containing materials, first metal microparticles, and second metal microparticles. Then, the post-sintered waste after pulverization can be separated into a first separated material and a second separated material by separating the finely pulverized post-sintered waste using a magnet in step (C). The first separated material includes the ceramic microparticles and the first metal microparticles. The second separated material includes the ceramic microparticles, rare earth-containing materials, and second metal microparticles. Therefore, by separating and recovering the first separated material in step (C), it is possible to remove the second separated material from the post-sintered waste, and to separate and recover the first separated material including the first metal microparticles as the first metal component.

Then, in step (D), the second separated material is dissolved in a mineral acid that has no oxidizing power, thereby producing a rare earth component-containing solution in which the rare earth components in the rare earth powder-containing material are dissolved. This allows the rare earth component-containing solution to be separated and recovered as rare earth components. At this time, the ceramic fine particles and the second metal fine particles in the second separated material have precipitated. The ceramic fine particles react with the mineral acid that has no oxidizing power, and become undissolved and precipitate. In addition, the second metal fine particles, such as Cu, do not dissolve in the mineral acid that has no oxidizing power, because they have a smaller ionization tendency than the hydrogen ions contained in the mineral acid that has no oxidizing power.

Then, by dissolving the ceramic fine particles and the second metal fine particles in the second separated product extracted in step (D) in ammonia water, a second metal solution can be produced in which the second metal components, such as Cu, in the second metal fine particles are dissolved. This makes it possible to separate and recover the second metal components from the second metal solution. At this time, the ceramic fine particles in the second separated product do not dissolve in the ammonia water but precipitate.

By going through the separation and recovery method including steps (C), (D) and (E), the rare earth components can be separated and recovered as a rare earth component-containing solution from the post-firing waste after micronization, and the second metal solution can be separated and recovered as a second metal component. Then, in the process of going through each step, the ratio of the rare earth components in the material containing the rare earth components and the ratio of the second metal components in the material containing the second metal components increase. Therefore, for example, rare earth components such as Dy and second metal components such as Cu can be recovered at high quality.

The separation and recovery method of the above embodiment further includes step (I). In step (I), the first separated material is dissolved in a mineral acid to produce a first metal solution in which the first metal component contained in the first metal fine particles is dissolved. In step (I), the ceramic fine particles contained in the first separated material react with the mineral acid to become undissolved and precipitate, so that the ceramic fine particles and the first metal component contained in the first separated material are separated.

Therefore, by going through the separation and recovery method including steps (C) and (I), the first metal solution can be separated and recovered as the first metal component from the post-firing waste after micronization. And, as each step goes through, the proportion of the first metal component in the material containing the first metal component increases. Therefore, the first metal component, such as Ni, can be recovered in high quality.

As described above, the first metal component, second metal component, rare earth component, etc. are separated and recovered from the fired waste of multilayer ceramic capacitors, so the fired waste is not discarded as waste but can be used as a resource, reducing the burden on the environment.

2. Experimental Example Hereinafter, an experimental example will be described in which metal components and rare earth components were recovered from post-burning waste.

[Example]
10 g of the fired waste was prepared. The 10 g of fired waste contained 35 mass % (3.5 g) of Ni, which is the first metal component, 7 mass % (0.7 g) of Cu, which is the second metal component, 54 mass % (5.4 g) of ceramic particles (ceramic sintered body) which is BaTiO ₃ , 2 mass % (0.2 g) of Dy, which is a rare earth component, and 2 mass % (0.2 g) of contaminants such as Mg, Mn, and SiO ₂ (step (A)). The fired waste was pulverized and finely divided (step (B)). The fired waste after pulverization and finely divided was mixed with 100 ml of water to prepare a slurry. The slurry was magnetically separated using a magnet. By this magnetic separation, 4.5 g of the first separated product was separated and recovered, and 4.6 g of the second separated product was separated and recovered (step (C)). Then, 100 ml of water was added to 4.6 g of the second separated product, and 1 mol% sulfuric acid was added little by little to adjust the pH to 2. As a result, the ceramic fine particles (BaTiO ₃ ) and the second metal fine particles (Cu) in the second separated product were precipitated, and the Dy contained in the rare earth-containing material was dissolved in the sulfuric acid solution (step (D)). The solution in which the ceramic fine particles (BaTiO ₃ ) and the second metal fine particles (Cu) were precipitated and Dy was dissolved in the sulfuric acid solution was filtered to obtain 90 ml of dysprosium sulfate (Dy ₂ (SO ₄ ) ₃ ) solution (step (F)). 1 mol% caustic soda solution was added little by little as an alkali to the 90 ml dysprosium sulfate solution to adjust the pH to 8 (step (G)). This solution was filtered to separate and recover 0.1 g of Dy(OH) ₃ . Therefore, by going through this process, approximately 40% of the Dy contained in the waste after firing was recovered.

In addition, 100 ml of water and 2 g of ammonium sulfate were added to 4.1 g of the filtrate of the ceramic fine particles (BaTiO ₃ ) and the second metal fine particles (Cu) recovered in step (F), and 1 mol% ammonia water was added little by little to adjust the pH to 9.5. This caused the ceramic fine particles (BaTiO ₃ ) to precipitate, and the second metal fine particles (Cu) to dissolve in ammonia water (step (E)). This solution was filtered to separate and recover 90 ml of ammine copper complexes such as [Cu(NH ₃ ) ₄ ] ²⁺ . Thus, by passing through this step, approximately 60% of the Cu contained in the waste after firing was recovered.

In addition, 100 ml of water was added to 4.5 g of the first separated product recovered in step (C), and 1 mol % sulfuric acid was added little by little to adjust the pH to 2. As a result, the ceramic fine particles (BaTiO ₃ ) in the first separated product were precipitated, and the first metal fine particles (Ni) were dissolved in the sulfuric acid solution (step (I)). The solution in which the ceramic fine particles (BaTiO ₃ ) were precipitated and the first metal fine particles (Ni) were dissolved in the sulfuric acid solution was filtered to obtain 90 ml of nickel sulfate (Ni(SO ₄ )) solution (step (J)). 1 mol % caustic soda solution was added little by little as an alkali to the 90 ml nickel sulfate solution to adjust the pH to 10. This solution was filtered, and 4.4 g of Ni(OH) ₂ was separated and recovered. Therefore, by going through this process, approximately 80% of the Ni contained in the waste after firing was recovered.

[Experimental Results]
From the above experiments, it has been found that the separation and recovery method according to the present embodiment uses fired multilayer ceramic capacitor waste as a starting material, and by going through processes such as magnetic separation and leaching by neutralization, it is possible to easily separate and refine high-quality rare earth components such as Dy, Ni, and Cu, a first metal component, and a second metal component.

Second Embodiment
In the first embodiment described above, the external electrode 30 includes a fired electrode layer 32. The fired electrode layer 32 is the outermost layer of the multilayer ceramic capacitor 10 (FIG. 3). However, the form of the external electrode 30 is not limited to this. In the second embodiment, the external electrode 30 includes a fired electrode layer 32 and a plating layer. The plating layer is the outermost layer of the multilayer ceramic capacitor. Descriptions of the same content as in the first embodiment will be omitted or simplified.

FIG. 7 is a cross-sectional view (1) parallel to a plane including the length direction and stacking direction of a multilayer ceramic capacitor according to a second embodiment of the present invention. FIG. 8 is a cross-sectional view (2) parallel to a plane including the length direction and stacking direction of another type of multilayer ceramic capacitor according to the second embodiment of the present invention.

The multilayer ceramic capacitors 10A (FIG. 7) and 10B (FIG. 8) according to the second embodiment include a laminate 12 similar to that of the first embodiment, and further include an external electrode 30 arranged on the laminate 12. The external electrode 30 includes a baked electrode layer 32 and a plating layer 34 arranged on the baked electrode layer 32. The plating layer 34 is the outermost layer of the multilayer ceramic capacitors 10A and 10B. The configuration other than the plating layer 34 is the same as that of the first embodiment. The plating layer 34 is formed by including at least one selected from, for example, Ni, Sn, Cu, Ag, etc. Note that the multilayer ceramic capacitor 10 according to the first embodiment does not include a plating layer (FIG. 3).

The multilayer ceramic capacitors 10A and 10B according to the second embodiment are formed through the steps (step 1) to (step 7) of the first embodiment described above, followed by a step (step 8) of disposing a plating layer 34 on the baked electrode layer 32. In step 8, a plating process is performed to form a first plating layer 34a (first lower plating layer 34a ₁ , first upper plating layer 34a ₂ ) on the first baked electrode layer 32a, and a second plating layer 34b (second lower plating layer 34b ₁ , second upper plating layer 34b ₂ ) on the second baked electrode layer 32b. The plating layer 34 is formed, for example, by barrel plating. Either electrolytic plating or electroless plating may be used for the plating process. However, electroless plating has the disadvantage that a pretreatment using a catalyst or the like is required to improve the plating deposition speed, which complicates the process. Therefore, it is usually preferable to use electrolytic plating.

The multilayer ceramic capacitors 10A and 10B having the plating layer 34 according to the second embodiment are also included in the post-sintering (sintering for fired electrode layers) waste, similar to the multilayer ceramic capacitor 10 according to the first embodiment (sometimes called the multilayer ceramic capacitor 10 without the plating layer 34). Depending on the material that constitutes the plating layer 34, the multilayer ceramic capacitors 10A and 10B having the plating layer 34 may be introduced into the separation and recovery method shown in FIG. 1 described above, or into the separation and recovery method shown in FIG. 9 described below. The separation and recovery method in FIG. 1 does not include a step of removing the plating layer 34, but the separation and recovery method in FIG. 9 includes a step of removing the plating layer 34 (step (K)).

The plating layer 34 may be formed from a single plating layer (FIG. 7) or may be formed by stacking multiple plating layers (FIG. 8). Below, we will explain a multilayer ceramic capacitor 10A in which the plating layer 34 is a single plating layer, and a multilayer ceramic capacitor 10B in which the plating layer 34 is a multiple plating layer. We will also explain a method for separating and recovering rare earth components and metal components from post-sintering waste for each of the multilayer ceramic capacitors 10A and 10B.

1. Structure of a Multilayer Ceramic Capacitor (1) Including a Single-Layer Plating Layer In a multilayer ceramic capacitor 10A shown in FIG. 7, an external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed of a single-layer plating layer. In the example of FIG. 7, the plating layer 34 includes a first lower-layer plating layer (first first-stage plating layer) 34a ₁ and a second lower-layer plating layer 34b ₁ (second first-stage plating layer). The first external electrode 30a includes a first baked electrode layer 32a and a first lower-layer plating layer 34a ₁ on the first baked electrode layer 32a. The second external electrode 30b includes a second baked electrode layer 32b and a second lower-layer plating layer 34b ₁ on the second baked electrode layer 32b. The first and second lower plating layers _34a1 , _34b1 are the outermost layers among the layers disposed on the laminate 12. The baked electrode layer 32 serves as a base for the plating layer 34, and is therefore sometimes referred to as a base electrode layer.

(2) Separation and Recovery Method (2-1) Overview of Separation and Recovery Method The multilayer ceramic capacitor 10A having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer) as in the first embodiment. Therefore, the multilayer ceramic capacitor 10A having the plating layer 34 can be input to the separation and recovery method of FIG. 1 described in the first embodiment. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10A having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10A having the plating layer 34 by going through the separation and recovery method described in FIG. 1.

However, it is also possible to recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10A after removing the plating layer 34 from the multilayer ceramic capacitor 10A having the plating layer 34. FIG. 9 is a flow diagram showing a method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor (firing for firing electrode layers), including a plating removal step. The separation and recovery method of FIG. 9, unlike the separation and recovery method of FIG. 1, includes a plating removal step (K) for removing the plating layer 34 between the preparation of the post-firing waste in step (A) and the refining in step (B). The separation and recovery method of FIG. 9 is the same as the separation and recovery method of FIG. 1, except for the inclusion of step (K).

When separating and recovering various components from a multilayer ceramic capacitor 10A having a plating layer 34, the method of separation and recovery shown in FIG. 1, which does not include a plating removal step, or the method of separation and recovery shown in FIG. 9, which includes a plating removal step, can be used, for example, as follows:

(2-2) In the case of using a separation and recovery method (FIG. 1) that does not include a plating removal step In a laminated ceramic capacitor 10A having a plating layer 34, the metal components contained in both the first and second lower plating layers 34a ₁ , 34b ₁ are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In this case, the laminated ceramic capacitor 10A having the plating layer 34 is prepared as a waste product after firing in step (A) of FIG. 1, and is further treated in each step after step (B) of the separation and recovery method shown in FIG. 1. For example, when the first metal component is contained in both the first and second lower plating layers 34a ₁ , 34b ₁ , the first metal component of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16. Furthermore, for example, when the second metal component is contained in both the first and second lower plating layers _34a1 , _34b1 , the second metal component of the plating layer 34 can be separated and recovered together with the second metal component contained in the baked electrode layer 32. It is possible to separate and recover the rare earth component from the ceramic layer 14.

Further, a specific example will be given. For example, it is assumed that both the first and second lower plating layers 34a ₁ and 34b ₁ are plating layers mainly composed of Ni. It is also assumed that the internal electrode layer 16 contains Ni as the first metal component. In this case, the multilayer ceramic capacitor 10A is prepared as a post-sintering waste in step (A) of FIG. 1 without removing the first and second lower plating layers 34a ₁ and 34b _1. Thereafter, by going through each step from step (B) onward in the separation and recovery method of FIG. 1, it is possible to separate and recover Ni, which is the first metal component, from the first and second lower plating layers 34a ₁ and 34b ₁ and the internal electrode layer 16. It is possible to separate and recover the second metal component from the fired electrode layer 32, and the rare earth component from the ceramic layer 14.

As another example, assume that both the first and second lower plating layers 34a ₁ and 34b ₁ are plating layers mainly composed of Cu. Also assume that the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A is prepared as waste after firing in step (A) of FIG. 1 without removing the first and second lower plating layers 34a ₁ and 34b _1. Thereafter, by going through each step from step (B) onward in the separation and recovery method of FIG. 1, the second metal component, Cu, can be separated and recovered from the first and second lower plating layers 34a ₁ and 34b ₁ and the baked electrode layer 32. Note that the first metal component can be separated and recovered from the internal electrode layer 16, and the rare earth component can be separated and recovered from the ceramic layer 14.

(2-3) Separation and recovery method including plating removal process (Figure 9)
In the multilayer ceramic capacitor 10A having the plating layer 34, the metal components contained in both the first and second lower plating layers 34a ₁ and 34b ₁ are different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In other words, the metal component (third metal component) contained in the first and second lower plating layers 34a ₁ and 34b ₁ is different from both the first metal component and the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as a post-sintering waste in step (A) of FIG. 9. Then, the first and second lower plating layers 34a ₁ and 34b ₁ are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed is further processed by each step after step (B) of the separation and recovery method shown in FIG. 9. This makes it possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the fired electrode layer 32, and the rare earth component contained in the ceramic layer 14 from the multilayer ceramic capacitor 10A from which the plating layer 34 has been removed.

Further, a specific example will be given for explanation. For example, it is assumed that both the first and second lower plating layers 34a ₁ and 34b ₁ are plating layers mainly composed of Sn (an example of a third metal component). It is also assumed that the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9. Then, in step (K) of FIG. 9, the first and second lower plating layers 34a ₁ and 34b ₁ mainly composed of Sn are removed. The first and second lower plating layers 34a ₁ and 34b ₁ mainly composed of Sn can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in an alkaline solution other than ammonia water, such as sodium hydroxide and potassium hydroxide. In this case, the baked electrode layer 32 mainly composed of Cu is exposed to the alkaline solution by removing the plating layer 34. However, the baked electrode layer 32 mainly composed of Cu is not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia water is adjusted to, for example, about pH 12. Thereafter, by going through each step from step (B) of the separation and recovery method of Figure 9 onwards, the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 can be separated and recovered.

In the above, the plating layer 34, which is mainly composed of Sn, is removed with an alkaline solution other than ammonia water. However, the plating layer 34, which is mainly composed of Sn, can be removed with an acidic solution that does not have oxidizing power, such as hydrochloric acid or dilute sulfuric acid. In this case, the baked electrode layer 32, which is mainly composed of Cu, is exposed to the acidic solution when the plating layer 34 is removed. However, the baked electrode layer 32, which is mainly composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, about pH 2.

Incidentally, even when the metal components contained in both the first and second lower plating layers _34a1 , _34b1 are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32, the multilayer ceramic capacitor 10A having the plating layer 34 may be prepared as waste after firing in step (A) of Fig. 9. Then, the first and second lower plating layers _34a1 , _34b1 may be removed by plating removal in step (K).

For example, it is assumed that both the first and second lower plating layers 34a ₁ and 34b ₁ are plating layers mainly composed of Ni. It is also assumed that the internal electrode layer 16 contains Ni as the first metal component, and the baked electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10A having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9. Then, in step (K) of FIG. 9, the first and second lower plating layers 34a ₁ and 34b ₁ mainly composed of Ni are removed. The first and second lower plating layers 34a ₁ and 34b ₁ mainly composed of Ni can be removed by immersing the multilayer ceramic capacitor 10A having the plating layer 34 in an acidic solution that does not have oxidizing power, such as hydrochloric acid and dilute sulfuric acid. In this case, the baked electrode layer 32 mainly composed of Cu is exposed to the acidic solution by removing the plating layer 34. However, the baked electrode layer 32, which is mainly composed of Cu, is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, a pH of about 2. Thereafter, by going through each step from step (B) of the separation and recovery method of Fig. 9 onwards, the first metal component constituting the internal electrode layer 16, the second metal component constituting the baked electrode layer 32, and the rare earth component contained in the ceramic layer 14 can be separated and recovered.

2. Structure of a multilayer ceramic capacitor (1) including multiple plating layers In a multilayer ceramic capacitor 10B shown in FIG. 8, an external electrode 30 includes a baked electrode layer 32 and a plating layer 34 disposed on the baked electrode layer 32. The plating layer 34 is formed of multiple plating layers. In the example of FIG. 8, the plating layer 34 is formed of two plating layers. Specifically, the plating layer 34 includes a first lower plating layer (first first-stage plating layer) _34a1 and a second lower plating layer (second first-stage plating layer) _34b1 , a first upper plating layer (first second-stage plating layer) _34a2 and a second upper plating layer (second second-stage plating layer) _34b2 . The first external electrode 30a includes a first baked electrode layer 32a, a first lower-layer plating layer _34a1 on the first baked electrode layer 32a, and a first upper-layer plating layer _34a2 on the first lower-layer plating layer _34a1 . The second external electrode 30b includes a second baked electrode layer 32b, a second lower-layer plating layer 34b1 on the second baked electrode layer _32b , and a second upper-layer plating layer 34b2 on the _second lower-layer plating layer _34b1 . The first upper-layer plating layer _34a2 and the second upper-layer plating layer _34b2 are the outermost layers among the layers arranged on the laminate 12.

The multilayer ceramic capacitor 10B having the plating layer 34 is formed through the steps (step 1) to (step 7) of the first embodiment described above, followed by a step (step 8) of disposing the plating layer 34 on the baked electrode layer 32. In (step 8), a plating process is performed to sequentially form a first lower-layer plating layer _34a1 and a first upper-layer plating layer _34a2 on the first baked electrode layer 32a, and a second upper-layer plating layer 34b2 on the second lower-layer plating layer _34b1 on the second baked electrode layer _32b .

(2) Separation and Recovery Method (2-1) Overview of Separation and Recovery Method The multilayer ceramic capacitor 10B having the plating layer 34 is included in the post-sintering waste (sintering for the fired electrode layer) as in the first embodiment. Therefore, the multilayer ceramic capacitor 10B having the plating layer 34 can be input to the separation and recovery method of FIG. 1 described in the first embodiment. That is, in the preparation of the post-sintering waste in step (A), the multilayer ceramic capacitor 10B having the plating layer 34 can be prepared as the post-sintering waste. Thereafter, the first metal component, the second metal component, and the rare earth component can be separated and recovered from the multilayer ceramic capacitor 10B having the plating layer 34 by going through the separation and recovery method described in FIG. 1.

However, it is also possible to remove the plating layer 34 from the multilayer ceramic capacitor 10B having the plating layer 34, and then recover the first metal component, the second metal component, and the rare earth component from the multilayer ceramic capacitor 10B.

When separating and recovering various components from a multilayer ceramic capacitor 10B having a plating layer 34, the method of separation and recovery shown in FIG. 1, which does not include a plating removal step, or the method of separation and recovery shown in FIG. 9, which includes a plating removal step, can be used, for example, as follows:

(2-2) In the case of using a separation and recovery method (FIG. 1) that does not include a plating removal step In a laminated ceramic capacitor 10B having a plating layer 34, the metal components contained in the first and second lower plating layers 34a ₁ , 34b ₁ and the first and second upper plating layers 34a ₂ , 34b ₂ are the same as at least one of the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. In this case, the laminated ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 1, and is treated by the separation and recovery method shown in FIG. 1. For example, the metal components of the first and second lower plating layers 34a ₁ , 34b ₁ may be the same as the first metal component contained in the internal electrode layer 16. Furthermore, the metal components of the first and second upper plating layers 34a ₂ , 34b ₂ may be the same as the second metal component contained in the baked electrode layer 32. Alternatively, for example, the metal components of the first and second lower plating layers _34a1 , _34b1 may be the same as the second metal component contained in the baked electrode layer 32. Furthermore, the metal components of the first and second upper plating layers _34a2 , _34b2 may be the same as the first metal component contained in the internal electrode layer 16. In this case, the first and second metal components of the plating layer 34 can be separated and recovered together with the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. It is to be noted that rare earth components can be separated and recovered from the ceramic layer 14.

Further, a specific example will be given for explanation. For example, the first and second lower plating layers _34a1 , _34b1 are plating layers mainly composed of Ni (or Cu). The first and second upper plating layers _34a2 , _34b2 are plating layers mainly composed of Cu (or Ni). The internal electrode layer 16 contains Ni as a first metal component. The baked electrode layer 32 contains Cu as a second metal component. In this case, the multilayer ceramic capacitor 10B is prepared as waste after firing in step (A) of FIG. 1 without removing the first and second lower plating layers _34a1 , _34b1 and the first and second upper plating layers _34a2 , _34b2 . 1, the first metal component Ni and the second metal component Cu can be separated and recovered from the first and second lower plating layers _34a1 , _34b1 and the first and second upper plating layers _34a2 , _34b2 , the internal electrode layer 16, and the baked electrode layer 32. Rare earth components can be separated and recovered from the ceramic layer 14.

(2-3) Separation and recovery method including plating removal process (Figure 9)
As an example, in a multilayer ceramic capacitor 10B having a plating layer 34, the metal component (third metal component) contained in the first and second lower plating layers 34a ₁ , 34b ₁ and the first and second upper plating layers 34a ₂ , 34b ₂ is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the fired electrode layer 32. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as a post-sintering waste in step (A) of FIG. 9. Then, the first and second lower plating layers 34a ₁ , 34b ₁ and the first and second upper plating layers 34a ₂ , 34b ₂ are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed is further processed by each step after step (B) of the separation and recovery method shown in FIG. 9. This makes it possible to separate and recover the first metal component constituting the internal electrode layer 16, the second metal component constituting the fired electrode layer 32, and the rare earth component contained in the ceramic layer 14 from the multilayer ceramic capacitor 10B from which the plating layer 34 has been removed.

As another example, in a laminated ceramic capacitor 10B having a plating layer 34, the (third metal component) contained in the first and second upper plating layers 34a ₂ , 34b ₂ is different from both the first metal component contained in the internal electrode layer 16 and the second metal component contained in the baked electrode layer 32. On the other hand, the metal components contained in the first and second lower plating layers 34a ₁ , 34b ₁ are the same as either the first metal component contained in the internal electrode layer 16 or the second metal component contained in the baked electrode layer 32. In this case, the laminated ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9. Then, the first and second upper plating layers 34a ₂ , 34b ₂ are removed by plating removal in step (K). Thereafter, the multilayer ceramic capacitor 10B from which the first and second upper plating layers _34a2 , _34b2 have been removed is further processed by each step subsequent to step (B) of the separation and recovery method shown in Fig. _9. As a result, the metal components (first metal component or second metal component) contained in the first and second lower plating layers _34a1 , _34b1 , the first metal component constituting the internal electrode layer ₁₆ , the second metal component constituting the fired electrode layer 32, and the rare earth components contained in the ceramic layer 14 can be separated and recovered from the multilayer ceramic capacitor 10B from which the first and second upper plating layers 34a2, 34b2 have been removed.

The above-mentioned other example will be described with a further specific example. For example, the metal component contained in the first and second upper plating layers 34a ₂ , 34b ₂ is a plating layer mainly composed of Sn (an example of a third metal component). Also, the metal component contained in the first and second lower plating layers 34a ₁ , 34b ₁ is a plating layer mainly composed of Ni (or Cu). Also, the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as waste after firing in step (A) of FIG. 9. Then, in step (K) of FIG. 9, the first and second upper plating layers 34a ₂ , 34b ₂ mainly composed of Sn are removed. The first and second upper plating layers 34a ₂ , 34b ₂ mainly composed of Sn can be removed by immersing the laminated ceramic capacitor 10B having the plating layer 34 in an alkaline solution other than ammonia water, such as sodium hydroxide and potassium hydroxide. In this case, the first and second lower plating layers 34a ₁ , 34b 1 mainly composed of Ni (or Cu) are exposed to the alkaline solution by removing the first and second upper plating layers 34a ₂ , 34b _2. However, the first and second lower plating layers 34a ₁ , 34b ₁ mainly composed of Ni (or Cu ₎ are not easily corroded by the alkaline solution. In addition, the baked electrode layer 32 mainly composed of Cu is also not easily corroded by the alkaline solution. Here, the alkaline solution other than ammonia water is adjusted to, for example, about pH 12. 9, the first metal component Ni and the second metal component Cu can be separated and recovered from the first and second lower plating layers _34a1 , _34b1 , the internal electrode layer 16, and the baked electrode layer 32. Rare earth components can be separated and recovered from the ceramic layer 14.

In the specific example of the above-mentioned other example, only the first and second upper plating layers 34a ₂ , 34b ₂ are removed in the step (K). However, both the first and second upper plating layers 34a ₂ , 34b ₂ and the first and second lower plating layers 34a ₁ , 34b ₁ may be removed. For example, the metal component contained in the first and second upper plating layers 34a ₂ , 34b ₂ is a plating layer mainly composed of Sn (an example of a third metal component). Also, the metal component contained in the first and second lower plating layers 34a ₁ , 34b ₁ is a plating layer mainly composed of Ni, not Cu. Also, the internal electrode layer 16 contains Ni as the first metal component, and the fired electrode layer 32 contains Cu as the second metal component. In this case, the multilayer ceramic capacitor 10B having the plating layer 34 is prepared as a post-sintering waste in the step (A) of FIG. 9. 9, the first and second upper plating layers 34a ₂ , 34b ₂ mainly composed of Sn and the first and second lower plating layers 34a 1 , 34b 1 mainly composed of Ni are removed. The first and second upper plating layers 34a ₂ , 34b ₂ mainly composed of Sn and the first and second lower plating layers _{34a 1 ,} 34b ₁ mainly composed of Ni can be removed by immersing the laminated ceramic capacitor 10B having the plating layer 34 in an acidic solution that does not have oxidizing power _, such as hydrochloric acid or dilute sulfuric acid. In this case, the baked electrode layer 32 mainly composed of Cu is exposed to the acidic solution by removing the plating layer 34. However, the baked electrode layer 32 mainly composed of Cu is not easily corroded by the acidic solution. Here, the acidic solution is adjusted to, for example, about pH 2. 9, the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

In the above, the first and second upper plating layers _34a2 , _34b2 mainly composed of Sn and the first and second lower plating layers _34a1 , _34b1 mainly composed of Ni are removed at the same time by the non-oxidizing acidic solution. However, they may be removed in order. First, the multilayer ceramic capacitor 10B is immersed in an alkaline solution (e.g., about pH 12) other than ammonia water, such as sodium hydroxide and potassium hydroxide, to remove the first and second upper plating layers _34a2 , _34b2 mainly composed of Sn. Then, the multilayer ceramic capacitor 10B is immersed in an acidic solution (e.g., about pH 2) other than ammonia water, such as hydrochloric acid and dilute sulfuric acid, to remove the first and second lower plating layers _34a1 , _34b1 mainly composed of Ni. 9, the first metal component Ni and the second metal component Cu can be separated and recovered from the internal electrode layer 16 and the fired electrode layer 32. The rare earth component can be separated and recovered from the ceramic layer 14.

3. Effects As in the first embodiment, from the multilayer ceramic capacitors 10A and 10B according to the second embodiment having the plating layer 34, the first metal component constituting the internal electrode layer 16, the second metal component constituting the external electrode 30, and the rare earth component contained in the ceramic layer 14 can be separated and recovered by the separation and recovery method shown in Fig. 1 or 9. Furthermore, by employing a separation and recovery method suitable for separating and recovering the metal components from the plating layer 34, the first metal component and the second metal component can also be recovered from the plating layer 34 in some cases.

As described above, the embodiment of the present invention has been disclosed in the above description, but the present invention is not limited thereto.
In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc. without departing from the scope of the technical idea and purpose of the present invention, and these are included in the present invention.

＜Other variations＞

(1) Generation of slurry by aqueous solvent in step (B) In the above-mentioned first and second embodiments, the calcination waste is pulverized and refined in step (B). However, as long as the calcination waste can be refined, the calcination waste may be refined by dispersing it in a solvent (e.g., an aqueous solvent or other solvent) in addition to the refinement in step (B) (particularly, refinement by pulverization), or instead of the refinement in step (B) (particularly, refinement by pulverization), in the slurry state. Here, the refinement in which the calcination waste is mixed with a solvent to form a slurry is called wet refinement. In addition, among the wet refinement, the refinement in which the calcination waste is pulverized in the slurry generated by mixing the calcination waste with a solvent is called wet grinding. In addition, as the aqueous solvent, for example, water can be used.

In addition, in the first and second embodiments described above, during magnetic separation in step (C), the calcined waste after being pulverized in step (B) can be mixed with an aqueous solvent such as water and dispersed to form a slurry state. However, as described above, when the calcined waste is made into a slurry state using an aqueous solvent in addition to or instead of the pulverization in step (B), the calcined waste in this slurry state can be magnetically separated in step (C). In other words, the effort of generating a slurry state in the magnetic separation in step (C) can be omitted.

It is also possible to make the post-calcination waste into a slurry using an organic solvent. However, if the post-calcination waste is made into a slurry using an organic solvent, a process for removing the organic solvent is required in the separation and recovery method. Therefore, it is preferable to make the post-calcination waste into a slurry using an aqueous solvent such as water.

(2) Other examples of waste after firing In the first and second embodiments described above, the waste after firing is waste after firing for the fired electrode layer in (step 7). However, the waste after firing is not limited to this. The waste after firing may include waste that has not been fired for the fired electrode layer and has been fired before being input to the separation and recovery method of FIG. 1 and FIG. 9. In this case, the firing is preferably performed at the firing temperature for the fired electrode layer.

Waste before firing for the baked electrode layer includes, for example, waste discharged in (step 1) to (step 6). In addition, waste before firing for the baked electrode layer may include waste after the paste for the baked electrode layer is applied to the laminate 12 in (step 7) but before firing for the baked electrode layer. Specifically, waste before firing for the baked electrode layer includes, for example, waste of dielectric slurry and conductive paste for the internal electrode layer in (step 1), waste of dielectric sheets on which the pattern of the internal electrode layer is formed in (step 2), dielectric sheets on which the pattern of the internal electrode layer is not printed, excess laminate blocks such as scraps of laminate blocks discharged after the laminate blocks are cut in (step 4), defective laminate chips after cutting, waste after degreasing in (step 5), and waste after firing of laminate chips in (step 6).

(3) Other Multilayer Ceramic Capacitors Discharged with Post-Firing Waste In the above first and second embodiments, a two-terminal multilayer ceramic capacitor having two terminals, the first external electrode 30a and the second external electrode 30b, has been described as a multilayer ceramic capacitor to be manufactured. However, the scope of application of the present invention is not limited to the post-firing waste of a two-terminal multilayer ceramic capacitor. The subject of application of the present invention is the post-firing waste of a multilayer ceramic capacitor having an internal electrode layer containing a first metal component such as Ni, an external electrode containing a second metal component such as Cu, and a ceramic layer containing a dielectric material such as _BaTiO3 and a rare earth component that is an additive such as Dy. Therefore, the present invention may be applied to, for example, the post-firing waste of a three-terminal multilayer ceramic capacitor.

For example, a three-terminal multilayer ceramic capacitor has a laminate 12 similar to those of the first and second embodiments described above, and first to fourth external electrodes. The internal electrode layer 16 has a first internal electrode layer extended to the first end face 12e and the second end face 12f, and a second internal electrode layer extended to the first side face 12c and the second side face 12d. A first external electrode is disposed on the first end face 12e of the laminate 12. The first external electrode is electrically connected to the first internal electrode layer exposed at the first end face 12e of the laminate 12. A second external electrode is disposed on the second end face 12f of the laminate 12. The second external electrode is electrically connected to the first internal electrode layer exposed at the second end face 12f of the laminate 12. A third external electrode is disposed on the first side face 12c of the laminate 12. The third external electrode is electrically connected to the second internal electrode layer exposed at the first side surface 12c of the laminate 12. A fourth external electrode is disposed on the second side surface 12d of the laminate 12. The fourth external electrode is electrically connected to the second internal electrode layer exposed at the second side surface 12d of the laminate 12. The first to fourth external electrodes may include only a baked electrode layer, or may include a baked electrode layer and a plating layer.

(4) Filtration in step (F) When the second separated material is dissolved in a mineral acid having no oxidizing power in step (D), the ceramic fine particles contained in the second separated material react with the mineral acid having no oxidizing power to become undissolved and precipitate. In addition, the second metal fine particles such as Cu have a smaller ionization tendency than the hydrogen ions contained in the mineral acid having no oxidizing power, so they do not dissolve in the mineral acid having no oxidizing power. On the other hand, the rare earth components in the rare earth-containing material dissolve to produce a rare earth component-containing solution. The rare earth component-containing solution containing the undissolved materials can also be recovered as the rare earth components. In this case, the solid-liquid separation step (F) such as filtration can be omitted.

(5) Omission of neutralization in step (G) In the first and second embodiments described above, in dissolving the second separated product in step (D), the rare earth components can be separated and recovered as a rare earth component-containing solution. Therefore, the neutralization in step (G) can be omitted.

(6) Omission of various treatments in steps (I) and (J) In the above first and second embodiments, in the magnetic separation in step (C), the first separated material containing the first metal fine particles can be separated and recovered as the first metal component. Therefore, steps (I) and (J) can be omitted. Also, in the dissolution of the first separated material in step (I), the first metal solution can be separated and recovered as the first metal component. Therefore, the filtration in step (J) can be omitted.

(7) Other methods for separating and recovering rare earth components In the first and second embodiments described above, rare earth component compounds such as Dy(OH) ₃ are separated and recovered as rare earth components in the neutralization step (G). However, the method for separating and recovering rare earth components is not limited to this. For example, the rare earth components can be recovered as follows.

(a)
The rare earth component compound obtained by neutralization in step (G) is heat-treated to produce an oxide, and the oxide can be recovered as the rare earth component.
For example, when the rare earth component compound obtained after the neutralization in step (G) is Dy(OH) ₃ , dysprosium oxide (Dy ₂ O ₃ ) can be recovered as the rare earth component by heat treating Dy(OH) ₃ .

(b)
The rare earth component compound obtained by neutralization in step (G) is dissolved in hydrochloric acid to produce a chloride, and the chloride can be recovered as the rare earth component.
For example, when the rare earth component compound obtained after the neutralization in step (G) is Dy(OH) ₃ , Dy(OH) ₃ is dissolved in hydrochloric acid to produce a dysprosium chloride ( _DyCl3 ) solution. The dysprosium chloride solution is distilled to evaporate the solvent, _and dysprosium chloride hexahydrate ( _DyCl3.6H2O ) can be recovered as the rare earth component.

(c)
Similarly to the above (b), the rare earth component compound Dy(OH) ₃ obtained after neutralization in step (G) is dissolved in hydrochloric acid to produce a dysprosium chloride solution, which is then further purified to recover high-purity rare earth components.
For example, the dysprosium chloride solution produced as described above can be purified by solvent extraction, and a high-purity dysprosium chloride solution can be recovered as a rare earth component. Solvent extraction is a separation and purification method that utilizes the partitioning of solutes, in which a solute dissolved in one of the oil phase and the water phase, which are immiscible liquids, is transferred to the other phase. As a method other than solvent extraction, for example, an ion exchange resin method can be used.

(d)
Also, high-purity dysprosium oxide ( _Dy2O3 ) can be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction in (c) above. In this case, for example _, first, oxalic acid is added _to the high-purity dysprosium chloride solution to precipitate dysprosium oxalate. By filtering this, high-purity dysprosium oxalate hexahydrate ( _Dy2 ( _C2O4 ) _3.6H2O ) is _recovered . By heat-treating this high-purity dysprosium oxalate hexahydrate, high-purity dysprosium oxide ( _Dy2O3 ) _can be recovered as a rare earth component.

(e)
Also, high-purity dysprosium chloride hexahydrate can be recovered from the high-purity dysprosium chloride solution obtained by the solvent extraction in (c) above. In this case, for example, high-purity dysprosium chloride hexahydrate is recovered by distilling off the high-purity dysprosium chloride solution and evaporating the solvent.

(f) State of the rare earth component The state of the recovered rare earth component may be any of a liquid state, a solid state, and a mixed state of liquid and solid. In addition, the crystal lattice of the rare earth component may be any of an amorphous state, a crystalline state, and a mixed state of amorphous and crystalline.

(8) Other methods for separating and recovering the first metal component In the first and second embodiments described above, the first metal fine particles are dissolved in a mineral acid in the dissolution of the first separated product in step (I). The first metal solution is then separated and recovered as the first metal component. In the subsequent filtering step (J), the first metal solution containing the precipitated ceramic fine particles is filtered, and the first metal solution from which the ceramic fine particles have been removed is separated and recovered as the first metal component. However, the separation and recovery of the first metal component is not limited to this. For example, the first metal component can be recovered as follows.

(a)
The first metal component compound can be recovered as the first metal component by crystallizing the first metal solution.
For example, when the first metal solution obtained after dissolving the first metal fine particles in step (I) is a nickel sulfate ( _NiSO4 ) solution, nickel sulfate hexahydrate ( _NiSO4.6H2O ) can be recovered as the first metal component by crystallizing and filtering _the nickel sulfate solution.

(b)
The first metal solution obtained after dissolving the finely divided first metal product in step (I) can be purified to recover a high-purity first metal component.
For example, a nickel sulfate (NiSO ₄ ) solution, which is the first metal solution, can be purified by an ion exchange resin method, a solvent extraction method, or the like, and a high-purity nickel sulfate solution can be recovered as the first metal component.

(c)
The high-purity nickel sulfate solution recovered in the above-mentioned (b) is crystallized and filtered, whereby nickel sulfate hexahydrate (NiSO ₄ .6H ₂ O) can be recovered as the first metal component.

(d)
The first metal solution obtained after dissolving the first metal fine particles in step (I) can be purified by a method other than the above-mentioned (b) to recover a high-purity first metal component.
For example, from a nickel sulfate solution, which is a first metal solution, solid high-purity Ni can be precipitated by a method of precipitating a solid dissolved in the solution, such as electrolytic deposition, and recovered as the first metal component.

(e)
By treating the high-purity Ni recovered in the above (d) _, nickel chloride hexahydrate ( _NiCl2.6H2O ) can be recovered as the first metal component. For example, by dissolving the high-purity Ni recovered in the above (d) in hydrochloric acid, a high-purity nickel chloride ( _NiCl2 ) solution is produced. By spray-drying the nickel chloride solution, high-purity nickel chloride hexahydrate is produced. By further drying the high-purity nickel chloride hexahydrate with hot air, even higher purity nickel chloride hexahydrate can be recovered as the first metal component.

(f)
The first metal solution obtained after dissolving the finely divided first metal product in step (I) is neutralized to generate a chloride, and the chloride can be recovered as the first metal component.
For example, a nickel sulfate solution, which is a first metal solution, is neutralized by adjusting the pH to, for example, about 10 (pH 9 or more and pH 11 or less) with an alkali such as sodium hydroxide or potassium hydroxide, and nickel hydroxide (Ni(OH) ₂ ) is precipitated. The precipitated nickel hydroxide (Ni(OH) ₂ ) is separated and recovered, for example, by filtration. Furthermore, nickel hydroxide is dissolved in hydrochloric acid to produce a nickel chloride ( _NiCl2 ) solution. Next, nickel chloride hexahydrate ( _NiCl2.6H2O ) can be recovered as the first metal component by distilling off the nickel chloride solution and evaporating _the solvent.

(g) State of the first metal component The state of the recovered metal component may be any of a liquid state, a solid state, and a mixed state of liquid and solid. In addition, the crystal lattice of the metal component may be any of an amorphous state, a crystalline state, and a mixed state of amorphous and crystalline.

(9) Other manufacturing steps of the multilayer ceramic capacitor In the above first and second embodiments, the manufacturing method of the multilayer ceramic capacitor 10 includes the formation of a laminated block (step 3), cutting into laminated chips (step 4), degreasing (step 5), firing of the laminated chips (step 6), and application and firing of the baked electrode layer paste (step 7) in that order. However, the manufacturing method of the multilayer ceramic capacitor 10 is not limited to this, and for example, before the degreasing in step 5 and before the firing (firing of the laminated chips) in step 6, the baked electrode layer paste may be applied to the unfired laminated chips, and then the degreasing and firing of the baked electrode layers may be performed. That is, first, the baked electrode layer paste containing Ni, glass components, resin components, etc. is applied to the laminated chips before the degreasing in step 5. Next, the laminated chips to which the baked electrode layer paste has been applied are degreased, and then the baked electrode layers are fired. The temperature during degreasing is preferably, for example, higher than 800° C. and lower than 1000° C. The firing temperature for the fired electrode layer is preferably, for example, higher than 1000° C. and not higher than 1400° C. These steps are performed after cutting into laminated chips in step 4 of the above-mentioned manufacturing method and before the plating step in step 8. In these steps, the firing of the laminated chips in step 6 and the firing of the paste for the fired electrode layer in step 7 are performed in a single firing.

＜1＞
(A) preparing post-sintering waste of a multilayer ceramic capacitor, the post-sintering waste comprising a laminate including a ceramic layer and an internal electrode layer, and a fired electrode layer disposed on the laminate as an outermost layer and connected to the internal electrode layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material including a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer includes a first metal component which is a magnetic base metal, the fired electrode layer includes a second metal component which is a non-magnetic precious metal, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) obtaining a ceramic fine-particle having the ceramic layer finely divided, the rare earth-containing material, a first metal fine-particle having the internal electrode layer finely divided, and a second metal fine-particle having the fired electrode layer finely divided by pulverizing the fired waste material;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated material containing the ceramic fine particles and the first fine metal particles, and a second separated material containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of:

＜2＞
(I) The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to <1>, further comprising a step of dissolving the first separation product after the step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic fine particles in the first separation product and generating a first metal solution in which the first metal component contained in the first metal fine particles in the first separation product is dissolved.

＜3＞
In the step (C), the finely divided post-sintering waste material in the step (B) is mixed with an aqueous solvent to generate a slurry, and then the first separated matter and the second separated matter are respectively recovered using the magnet.

＜4＞
The method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor according to any one of <1> to <3>, wherein in the step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid having no oxidizing power.

＜5＞
The method for separating and recovering rare earth components and metal components from waste after firing of a multilayer ceramic capacitor according to any one of <1> to <4>, wherein in the step (E), the second metal solution is adjusted to a pH of 9 or more and 10 or less by adding the ammonia water.

＜6＞
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <5>, wherein the first metal component is Ni.

＜７＞
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <6>, wherein the second metal component is Cu.

＜8＞
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <7>, wherein the ceramic particles are BaTiO ₃ .

＜9＞
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of <1> to <8>, wherein the rare earth components are at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu.

＜10＞
(A) preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; and a first-stage plating layer disposed on the fired electrode layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component which is a magnetic base metal, the fired electrode layer contains a second metal component which is a non-magnetic precious metal, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) obtaining a ceramic micro-fine product in which the ceramic layer is micro-fine, the rare earth-containing material, the internal electrode layer and the first-stage plating layer are micro-fine, and a second metal micro-fine product in which the baked electrode layer is micro-fine, by micro-fine-refining the fired waste;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated material containing the ceramic fine particles and the first fine metal particles, and a second separated material containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of:

<11>
(A) a step of preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; a first-stage plating layer disposed on the fired electrode layer; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles; the internal electrode layer contains a first metal component which is a magnetic base metal; the fired electrode layer contains a second metal component which is a non-magnetic precious metal; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(K) removing at least the second-stage plating layer from the first-stage plating layer and the second-stage plating layer in the fired waste;
(B) a step of pulverizing the fired waste from which at least the second-stage plating layer has been removed by the step (K) to obtain a ceramic micro-particle in which the ceramic layer has been micro-particled, the rare earth-containing material, the internal electrode layer and the first-stage plating layer have been micro-particled, and a second metal micro-particle in which the baked electrode layer has been micro-particled;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated matter containing the ceramic fine particles and the first fine metal particles, and a second separated matter containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of:

10: Multilayer ceramic capacitor 12: Laminate 12a: First main surface 12b: Second main surface 12c: First side surface 12d: Second side surface 12e: First end surface 12f: Second end surface 14: Ceramic layer 14_U: Unfired ceramic layer 16: Internal electrode layer 16_U: Unfired internal electrode layer 16a: First internal electrode layer 16b: Second internal electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 32: Baked electrode layer 32a: First baked electrode layer 32b: Second baked electrode layer 34: Plating layer 34a: First plating layer _34b : Second plating layer _34a1 : First lower plating layer 34a2: First upper plating layer _34b1 : second lower plating layer _34b2 : second upper plating layer x: height direction y: width direction z: length direction

Claims (11)

(A) preparing post-sintering waste of a multilayer ceramic capacitor, the post-sintering waste comprising a laminate including a ceramic layer and an internal electrode layer, and a fired electrode layer disposed on the laminate as an outermost layer and connected to the internal electrode layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material including a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer includes a first metal component which is a magnetic base metal, the fired electrode layer includes a second metal component which is a non-magnetic precious metal, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) obtaining a ceramic fine-particle having the ceramic layer finely divided, the rare earth-containing material, a first metal fine-particle having the internal electrode layer finely divided, and a second metal fine-particle having the fired electrode layer finely divided by pulverizing the fired waste material;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated material containing the ceramic fine particles and the first fine metal particles, and a second separated material containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of: (I) The method for separating and recovering rare earth and metal components from post-sintering waste of multilayer ceramic capacitors according to claim 1, further comprising the step of dissolving the first separated product after step (C) in at least one mineral acid selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, thereby precipitating the ceramic fine particles in the first separated product and producing a first metal solution in which the first metal component contained in the first metal fine particles in the first separated product is dissolved. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to claim 1 or 2, wherein in step (C), the post-sintering waste finely divided in step (B) is mixed with an aqueous solvent to produce a slurry, and then the first separated material and the second separated material are respectively recovered using the magnet. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 3, wherein in step (D), the rare earth component-containing solution is adjusted to a pH of 1.5 or more and 2.5 or less by adding the mineral acid having no oxidizing power. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 4, wherein in step (E), the second metal solution is adjusted to a pH of 9 or more and 10 or less by adding the ammonia water. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 5, wherein the first metal component is Ni. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 6, wherein the second metal component is Cu. 8. The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors according to claim 1, wherein the ceramic particles are _BaTiO3 . The method for separating and recovering rare earth and metal components from post-sintering waste of multilayer ceramic capacitors according to any one of claims 1 to 8, wherein the rare earth component is at least one of Dy, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu. (A) preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; and a first-stage plating layer disposed on the fired electrode layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles, the internal electrode layer contains a first metal component which is a magnetic base metal, the fired electrode layer contains a second metal component which is a non-magnetic precious metal, the first-stage plating layer contains the first metal component, and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(B) obtaining a ceramic micro-fine product in which the ceramic layer is micro-fine, the rare earth-containing material, the internal electrode layer and the first-stage plating layer are micro-fine, and a second metal micro-fine product in which the baked electrode layer is micro-fine, by micro-fine-refining the fired waste;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated material containing the ceramic fine particles and the first fine metal particles, and a second separated material containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of: (A) a step of preparing sintered waste of a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a laminate including a ceramic layer and an internal electrode layer; a fired electrode layer disposed on the laminate and connected to the internal electrode layer; a first-stage plating layer disposed on the fired electrode layer; and a second-stage plating layer disposed on the first-stage plating layer as an outermost layer, the ceramic layer having an aggregate of a plurality of ceramic particles, a rare earth-containing material containing a rare earth component is contained in grain boundaries between the plurality of ceramic particles; the internal electrode layer contains a first metal component which is a magnetic base metal; the fired electrode layer contains a second metal component which is a non-magnetic precious metal; the first-stage plating layer contains the first metal component; the second-stage plating layer contains a third metal component; and the ceramic layer, the internal electrode layer, and the fired electrode layer are sintered;
(K) removing at least the second-stage plating layer from the first-stage plating layer and the second-stage plating layer in the fired waste;
(B) a step of pulverizing the fired waste from which at least the second-stage plating layer has been removed by the step (K) to obtain a ceramic micro-particle in which the ceramic layer has been micro-particled, the rare earth-containing material, the internal electrode layer and the first-stage plating layer have been micro-particled, and a second metal micro-particle in which the baked electrode layer has been micro-particled;
(C) a step of separating and recovering the fired waste after the step (B) into a first separated matter containing the ceramic fine particles and the first fine metal particles, and a second separated matter containing the ceramic fine particles, the rare earth-containing material, and the second fine metal particles, using a magnet;
(D) dissolving the second separated product after the step (C) in at least one mineral acid having no oxidizing power selected from the group consisting of dilute sulfuric acid and hydrochloric acid, thereby precipitating the ceramic fine particles and the second metal fine particles in the second separated product and generating a rare earth component-containing solution in which the rare earth components in the rare earth-containing product are dissolved;
(E) dissolving the ceramic fine particles and the second metal fine particles in the second separation product precipitated in the step (D) in ammonia water to precipitate the ceramic fine particles in the second separation product and generate a second metal solution in which the second metal component contained in the second metal fine particles is dissolved;
The method for separating and recovering rare earth components and metal components from post-sintering waste of multilayer ceramic capacitors comprises the steps of: