WO2018194165A1 - Method for smelting metal oxide - Google Patents

Abstract

Provided is a smelting method whereby reduction by a carbonaceous reducing agent is performed to obtain a reduced substance using as a raw material a nickel oxide ore or other metal oxide containing oxidized nickel or the like, for example, wherein a high-quality reduced substance can be obtained with high efficiency. The method for smelting a metal oxide pertaining to the present invention comprises reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reducing furnace, wherein the mixture obtained by mixing a metal oxide and a carbonaceous reducing agent is heated and reduced on a floor covering material composed of one or more types of materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite.

Description

Metal oxide smelting method

The present invention relates to a metal oxide smelting method, for example, a smelting method of obtaining a reduced product by reducing nickel oxide ore or the like as a raw material with a carbonaceous reducing agent.

As a smelting method of nickel oxide ore called limonite or saprolite which is a kind of metal oxide ore, dry smelting method to produce nickel matte using smelting furnace, rotary kiln or moving hearth furnace HPAL, a dry smelting method for producing ferronickel, which is an alloy of iron and nickel, and a hydrometallurgical method for obtaining nickel cobalt mixed sulfide (mixed sulfide) by adding a high-pressure acid leaching sulfiding agent using an autoclave Processes are known.

Among the various methods described above, particularly when nickel oxide ore is reduced and smelted using a dry smelting method, the raw material nickel oxide ore is crushed to an appropriate size to advance the reaction. Then, the process of forming a lump is performed as a pretreatment.

Specifically, when a nickel oxide ore is agglomerated, that is, when it is made into a lump from powder or fine particles, the nickel oxide ore and other components, for example, a reducing agent such as a binder or coke are mixed to form a mixture. Further, after performing moisture adjustment and the like, it is inserted into a lump manufacturing machine, for example, a lump or a lump called a pellet or briquette with a diameter of about 10 mm to 30 mm (hereinafter collectively referred to as “pellet”). ).

Now, the pellet needs to have a certain degree of air permeability in order to “fly” the contained moisture. In addition, if the reduction does not proceed uniformly in the pellet, the composition of the resulting reduced product becomes non-uniform, resulting in inconveniences such as metal dispersion or uneven distribution. It is important to maintain a uniform temperature as much as possible when the reduction treatment is performed.

In addition, it is an important technique to coarsen the reduced ferronickel produced. This is because when the produced ferronickel has a fine size of, for example, several tens of μm to several hundred μm, it is difficult to physically separate from the slag produced at the same time, and the recovery rate (yield as ferronickel) ) Is greatly reduced.

Also, how to keep the smelting cost low is an important technical matter, and continuous processing that can be operated with compact equipment is desired.

For example, in Patent Document 1, an agglomerate containing iron oxide as a metal oxide and a carbonaceous reducing agent is supplied onto a hearth of a moving bed type reductive melting furnace, heated, reduced and melted, and then obtained granules. In the method of cooling and recovering the metal to the outside of the furnace, the internal temperature in the first half of the furnace for solid reduction of iron oxide in the agglomerate is 1300 to 1450 ° C., and the reduced iron in the agglomerate is reduced. The maximum temperature of the agglomerate to the hearth when the in-furnace temperature in the latter half region of the carburizing, melting and agglomerating furnace is 1400 to 1550 ° C. and the distance between the agglomerates spread on the hearth is 0 With respect to the projected area ratio, when the relative value of the projected area ratio of the agglomerate spread on the hearth to the hearth is defined as the bed density, the agglomerated floor density on the hearth is 0.5 or more and 0.8 or less. When heating as an average diameter of 19.5 mm or more and 32 mm or less The method for supplying agglomerates to the hearth are disclosed.

According to such a method of Patent Document 1, it is described that the productivity of granular metallic iron can be improved by controlling together with the agglomerated bed density and the average diameter. As this patent document 1 shows, productivity of granular metal iron can be improved by controlling the bed density and average diameter of an agglomerate. However, Patent Document 1 is a technique relating to the reaction on the outer surface of the agglomerate. In contrast, the reduction reaction is a reaction inside the agglomerate. Therefore, in the method of Patent Document 1, it is difficult to control the reduction reaction in the agglomerate.

Further, when the diameter of the agglomerate is limited to a predetermined range as in Patent Document 1, there is a problem in that the yield during the production of the agglomerate is lowered and the cost is increased. Further, when the density of the agglomerated material is in the range of 0.5 to 0.8, the efficiency is low because the agglomerated material is not in a close-packed state and is not a state in which the agglomerated material is laminated. Further, when a moving hearth furnace such as that disclosed in Patent Document 1 is used, since the operation is continuously performed, it is also important to constantly maintain the state of the furnace.

Furthermore, as in Patent Document 1, the process using the so-called total melting method in which all raw materials are melted and reduced has a big problem in terms of operation cost. For example, in order to completely melt the nickel oxide ore described above, it is necessary to heat to a high temperature of 1500 ° C. or higher. In order to obtain such a high temperature, a large energy cost is required, and the furnace used at such a high temperature is easily damaged, so that the repair cost also increases. The target nickel is contained only about 1% in the raw material nickel oxide ore. Therefore, it is not necessary to recover the iron component in excess of the stoichiometric amount necessary for reacting with nickel to form ferronickel, but to melt even a large amount of unnecessary components. Is significantly inefficient.

For this reason, only the necessary nickel is preferentially reduced and the iron contained in a much larger amount than nickel is reduced only partially. The reduction method by partial melting ("partial reduction method" or nickel preferential reduction). (Also called the law) has been studied.

However, in such a partial reduction method, since the raw material is not completely melted and the reduction reaction is performed while maintaining a semi-solid state, nickel is completely reduced while iron is reduced only once. It is not easy to control the reaction so that only the part remains. For this reason, the partial dispersion | variation arises in the reduction | restoration within a raw material, and efficient operations, such as a fall of a nickel recovery rate, were difficult.

By the way, the material of the reducing furnace that reacts at a high temperature becomes a problem. A normal fixed-bed furnace has a structure in which refractory bricks are placed on a frame made of cast iron or the like. However, in a rotary hearth furnace, the hearth and the furnace wall are less than the fixed bed in order to reduce the power required for rotation. In many cases, a lighter and thinner structure is employed. In such a case, a hearth material (also called “floor material”) is laid on the hearth to protect the hearth from the reaction between the treated material and the hearth and the treated material being seized on the hearth. Measures are taken.

Conventionally, it has been common to use coal or coke as the flooring material. Since these also act as reducing agents at the same time, they are not suitable when it is necessary to accurately control and maintain the reducing state in the furnace. In addition, at high temperatures, the effect as a flooring material disappears by reacting with the atmospheric gas and the processed material, making it difficult to use repeatedly and increasing the cost.

Thus, it is not easy to reduce the metal oxide with high efficiency and obtain a high-quality reduced product.

JP 2011-256414 A

The present invention has been proposed in view of such circumstances. For example, a metal oxide such as nickel oxide ore containing nickel oxide or the like is used as a raw material, and reduced by a carbonaceous reducing agent to obtain a reduced product. In the smelting method, a method capable of obtaining a high-quality reduced product with high efficiency is provided.

The present inventors have made extensive studies to solve the above-described problems. As a result, a specific flooring material is used or a flooring material is laid on the hearth in a specific arrangement, and a metal oxide is reduced on the flooring material with a carbonaceous reducing agent to obtain a reduced product. Thus, it was found that an efficient smelting treatment can be performed, and the present invention has been completed. Specifically, the present invention provides the following.

(1) A first invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, comprising alumina, A metal oxide smelting method in which the mixture is heated and reduced on a floor covering composed of one or more materials selected from alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. .

(2) According to a second aspect of the present invention, in the first aspect, the flooring material is composed of particles of the material (flooring material particles) and is obtained from the following formulas (1) and (2). This is a metal oxide smelting method in which the average floor covering volume ratio is 3% or more and 85% or less.
Average floor covering volume ratio = total floor covering volume ratio of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere having diameter of maximum particle length of floor covering particles) × 100 (2)

(3) According to a third aspect of the present invention, in the first or second aspect, the flooring material is composed of particles of the material (flooring material particles) and is an average obtained from the following formula (3): This is a metal oxide smelting method having a maximum particle length of 10 μm or more and 6000 μm or less.
Average maximum particle length = sum of maximum particle lengths of 300 flooring particles / 300 (3)

(4) A fourth invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, and having a specific surface area On a floor covering composed of particles (floor covering particles) having an average maximum particle length of not less than 15.0 μm and not more than 2000 μm in a range of 0.001 μm ^{−1 to} 3.0 μm ^−1. This is a method for smelting metal oxides by heating and reducing.

(5) According to a fifth aspect of the present invention, in the fourth aspect, the flooring material particles are one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. This is a method for smelting a metal oxide.

(6) A sixth invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace, wherein the reduction A flooring material is laid on the hearth of the furnace, the flooring material is composed of particles (flooring material particles), and the number of flooring material particles having a maximum particle length of 50.0 μm or less contained in the flooring material is It is 1% or more and 40% or less with respect to the total number of flooring material particles contained in the flooring material, and the flooring material particles have an average maximum particle length of 40.0 μm or more and 1050 μm determined by the following formula (3). The following is a method for smelting a metal oxide.
Average maximum particle length = sum of maximum particle lengths of 300 flooring particles / 300 (3)

(7) A seventh invention of the present invention is a metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
Laying flooring material on the hearth of the reduction furnace,
A metal oxide smelting method in which the mixture is placed on the floor covering material so as to be 50% or less of the area of the hearth when viewed in plan, and heated and reduced.

(8) The eighth invention of the present invention is the method for smelting a metal oxide according to the seventh invention, wherein the mixture has any one of a spherical shape, a cubic shape, and a rectangular parallelepiped shape.

(9) A ninth invention of the present invention is a metal oxide smelting method according to any one of the first to eighth inventions, wherein the reduction temperature is 1200 ° C. or higher and 1450 ° C. or lower.

(10) A tenth aspect of the present invention is the method for smelting a metal oxide according to any one of the first to ninth aspects, wherein the metal oxide is nickel oxide ore.

(11) The eleventh invention of the present invention is a metal oxide smelting method according to any one of the first to tenth inventions, wherein the reduced product contains ferronickel.

According to the present invention, for example, in a smelting method in which a metal oxide such as nickel oxide ore containing nickel oxide or the like is used as a raw material and reduced with a carbonaceous reducing agent to obtain a reduced product, Can be obtained efficiently.

It is process drawing which shows an example of the flow of the smelting method of nickel oxide ore. It is a process which shows the process process performed in a reduction process process. It is a figure (plan view) showing an example of composition of a rotary hearth furnace where a hearth rotates. It is a schematic diagram of an irregular particle and a sphere whose diameter is the maximum particle length. It is a schematic diagram which shows the maximum particle length of an amorphous particle. It is a schematic diagram which shows the example of installation of the spherical mixture with respect to a floor covering material. It is a schematic diagram which shows the example of installation of the rectangular parallelepiped mixture with respect to a floor covering material.

<< 1. Outline of the present invention >>
The metal oxide smelting method according to the present invention is a smelting method in which a metal oxide is used as a raw material to perform a reduction treatment at a high temperature with a carbonaceous reducing agent to obtain a reduced product. For example, nickel oxide ore containing nickel oxide, iron oxide, etc. as a metal oxide is used as a raw material, and the nickel is prioritized at a high temperature by a carbonaceous reducing agent with respect to the smelting raw material. A method for producing ferronickel by reduction to the above.

Specifically, this metal oxide smelting method uses a specific floor covering material or lays a floor covering material on a hearth in a specific arrangement, and the metal oxide is carbonaceous on the floor covering material. It is characterized by being reduced by a reducing agent, and has four embodiments as specific embodiments. In the first aspect, a metal oxide and a carbonaceous reducing agent are formed on a floor covering made of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite. The mixture obtained by mixing is reduced. In a second aspect, and a specific surface area of 0.001 [mu] m ^-1 or more 3.0 [mu] m ^-1 or less, and an average maximum particle length on configured bedding material from the particles is less than 2000μm or 15.0μm, the metal It is characterized in that a mixture obtained by mixing an oxide and a carbonaceous reducing agent is reduced. In the third aspect, when reducing the mixture obtained by mixing the metal oxide and the carbonaceous reducing agent in the reducing furnace, the particles are composed of particles and have a maximum particle length of 50.0 μm or less. The number of particles is 1% or more and 40% or less with respect to the total number of particles in the flooring material, and the average maximum particle length is 40.0 μm or more and 1050 μm or less. To do. In the fourth aspect, when reducing the mixture obtained by mixing the metal oxide and the carbonaceous reducing agent in the reduction furnace, the metal oxide is reduced with the carbonaceous reducing agent in the main furnace. In the smelting process to obtain a reduced product, a floor covering material is laid on the hearth of the reduction furnace, and the mixture is placed on the floor covering material so that it becomes 50% or less of the area of the hearth when viewed in plan. It is arranged and reduced.

According to such a smelting method, the metal contained in the metal oxide can be effectively metallized, and an efficient smelting process can be performed.

Hereinafter, as a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”), a method for smelting nickel oxide ore will be described as an example. Nickel oxide ore, which is a smelting raw material, contains at least nickel oxide. In this nickel oxide ore smelting method, ferronickel (iron-nickel alloy) is reduced by reducing nickel oxide contained in the raw material. Can be manufactured.

It should be noted that the present invention is not limited to nickel oxide ore as a metal oxide, and the smelting method is not limited to a method for producing ferronickel from nickel oxide ore containing nickel oxide or the like. Various changes can be made without departing from the scope of the present invention.

≪2. Nickel oxide ore smelting method >>
The nickel oxide ore smelting method according to the present embodiment is made by mixing and kneading nickel oxide ore, which is a smelting raw material, with a carbonaceous reducing agent or the like to form a mixture and subjecting the mixture to a reduction treatment. In this method, ferronickel, which is a metal, and slag are produced as reduction products. In addition, the ferronickel which is a metal can be collect | recovered by isolate | separating the metal from the mixture containing the metal and slag obtained through the reduction process.

FIG. 1 is a process diagram showing an example of the flow of a nickel oxide ore smelting method. As shown in FIG. 1, this nickel oxide ore smelting method comprises mixing treatment step S1 in which nickel oxide ore and a material such as a carbonaceous reducing agent are mixed to obtain a mixture, and the resulting mixture is agglomerated or A reduction pre-treatment process S2 that fills and molds a predetermined container, a reduction process S3 that reduces the mixture at a predetermined temperature (reduction temperature), and a metal from a mixture that includes the metal and slag generated by the reduction process. Separating step S4 for separating and collecting.

<2-1. Mixing process>
The mixing treatment step S1 is a step of obtaining a mixture by mixing raw material powders containing nickel oxide ore. Specifically, in the mixing treatment step S1, nickel oxide ore which is a smelting raw material, iron source such as iron ore, flux component, binder, carbonaceous reducing agent, etc., for example, a particle size of 0.1 mm to 0.8 mm About a raw material powder is mixed at a predetermined ratio to obtain a mixture.

The nickel oxide ore, which is a smelting raw material ore, is not particularly limited, and limonite or saprolite ore can be used.

The iron source supplies iron necessary for reacting with nickel in nickel oxide ore to form ferronickel. As the iron source, for example, iron ore having an iron grade of about 50% or more, hematite obtained by wet smelting of nickel oxide ore, or the like can be used.

Table 1 below shows an example of the composition (wt%) of nickel oxide ore and iron ore as raw materials. In addition, as a composition of a raw material, it is not limited to this.

Examples of the binder include bentonite, polysaccharides, resins, water glass, and dehydrated cake. Examples of the flux component include calcium oxide, calcium hydroxide, calcium carbonate, silicon dioxide and the like.

Although it does not specifically limit as a carbonaceous reducing agent, For example, coal powder, coke, etc. are mentioned. In addition, it is preferable that this carbonaceous reducing agent has a magnitude | size equivalent to the particle size of the nickel oxide ore of a raw material ore. In addition, as the mixing amount of the carbonaceous reducing agent, for example, the chemical equivalent required to reduce the total amount of nickel oxide contained in the formed mixture to nickel metal and the ferric oxide contained in the pellets as metal When the total value of both chemical equivalents necessary for reduction to iron (also referred to as “total value of chemical equivalents” for convenience) is 100%, the carbon content is preferably 5% by mass to 60% by mass It is possible to adjust the ratio so as to be a ratio of carbon amount of 10% by mass to 40% by mass.

The mixing amount of the carbonaceous reducing agent is such that the amount of carbon is 5% by mass or more with respect to 100% of the total value of chemical equivalents, whereby the reducibility of nickel can be further increased and the productivity can be increased. On the other hand, by reducing the amount of carbon to 60% by mass or less, it is possible to suppress the reduction reaction from proceeding excessively, to suppress an increase in the reduction amount of iron and the accompanying decrease in nickel quality in ferronickel, The quality in the obtained ferronickel alloy can be further improved. Thus, by setting the ratio of the carbon amount to 5% by mass or more and 60% by mass or less, a shell (metal shell) generated by a metal component can be uniformly generated on the surface of the raw material in the shape of pellets or the like. More preferable in terms of productivity and quality.

The “pellet” refers to a lump obtained by molding a mixture obtained by mixing at least the oxide ore and the carbonaceous reducing agent, and may be simply referred to as “mixture”.

In the mixing treatment step S1, a mixture is obtained by uniformly mixing the raw material powder containing the nickel oxide ore as described above. In this mixing, kneading may be performed simultaneously, or kneading may be performed after mixing. Thus, by mixing and kneading the raw material powder, the contact area between the raw materials is increased and the voids are reduced, so that a reduction reaction is easily caused and a uniform reaction can be achieved. Thereby, the reaction time of the reduction reaction can be shortened, and quality variation is eliminated. As a result, it is possible to process with high productivity and to manufacture high quality ferronickel.

Further, after the raw material powder is kneaded, it may be extruded using an extruder. Thus, by extruding with an extruder, a much higher kneading effect can be obtained, the contact area between the raw material powders can be increased, and the voids can be reduced. Thereby, high quality ferronickel can be produced efficiently.

<2-2. Reduction input pretreatment process (pretreatment process)>
The pre-reduction process step S2 is a step in which the mixture obtained in the mixing step S1 is agglomerated into a mass or filled into a container and molded. That is, in this pre-reduction charging treatment step S2, the mixture obtained by mixing the raw material powders can be easily put into a furnace used in the reduction treatment step S3 described later, and the reduction reaction can be efficiently performed. Mold.

(Agglomeration of the mixture)
When the obtained mixture is agglomerated, the mixture is molded (granulated) into a lump. Specifically, a predetermined amount of moisture necessary for agglomeration is added to the obtained mixture, and for example, an agglomerate production apparatus (such as a tumbling granulator, a compression molding machine, an extrusion molding machine, etc.) And the like (hereinafter also referred to as “pellets”).

The shape of the pellet is not particularly limited, and may be a spherical shape, a cubic shape, a rectangular parallelepiped shape, or the like. For example, a spherical pellet is preferable because the reduction reaction easily proceeds relatively uniformly. Moreover, since it is a cube shape and a rectangular parallelepiped pellet, it can be stably mounted on the floor covering material laid on the hearth, and handling property improves.

In addition, the size of the lump to be pelletized is not particularly limited. For example, in order to perform the reduction process (reduction process S33) through the drying process (drying process S31) and the preheating process (preheating process S32). The size of the pellets charged into the smelting furnace to be used (diameter in the case of spherical pellets) can be about 10 mm to 30 mm. Details of the reduction step will be described later.

(Filling the mixture into the container)
When the obtained mixture is filled into a container and molded, the mixture can be filled into a predetermined container while kneading with an extruder or the like. The mixture filled in the container is preferably pressed and hardened. By pressing and solidifying the mixture in the container, taking out from the container and subjecting it to the subsequent reduction treatment step S3, the density of the mixture can be increased, the density becomes uniform, and the reduction reaction proceeds more uniformly. Thus, ferronickel with small quality variation can be manufactured.

The shape of the mixture filled in the container is not particularly limited, but is preferably, for example, spherical, rectangular parallelepiped, cubic or cylindrical. Moreover, although the size is not particularly limited, for example, if it is spherical, it is preferable that the diameter is approximately 500 mm or less. For example, in the case of a rectangular parallelepiped shape or a cubic shape, it is generally preferable that the vertical and horizontal inner dimensions are 500 mm or less. By adopting such a shape and size, smelting with small quality variation and high productivity can be performed.

<2-3. Reduction process>
In the reduction treatment step S3, for example, the raw material powder is mixed in the mixing treatment step S1 and the mixture agglomerated in the reduction charging pretreatment step S2 or the mixture filled in the container and molded is predetermined in the reduction furnace. Reduce and heat at the reduction temperature of And a smelting reaction advances by the reduction | restoration heat processing of the mixture in reduction process process S3, and a metal and slag produce | generate.

Here, at the time of this heat reduction, as the flooring material, a material composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite is used. By placing such a flooring material on the hearth of the reduction furnace and placing the mixture on the flooring material and reducing the heat, the direct reaction between the mixture and the hearth of the reduction furnace can be suppressed. it can. Moreover, reaction with a mixture can be suppressed by using the kind of floor covering material as described above, and high-quality ferronickel can be produced. In addition, since reaction with a mixture is suppressed, the flooring material can be reused and smelting cost can be reduced.

FIG. 2 is a process diagram showing the process executed in the reduction process S3. As shown in FIG. 2, the reduction treatment step S3 includes a drying step S31 for drying the mixture, a preheating step S32 for preheating the dried mixture, a reduction step S33 for reducing the mixture, and cooling the obtained reduction product. Cooling step S35. Moreover, it has the temperature holding process S34 which hold | maintains the reduced material obtained through reduction process S33 in a predetermined temperature range.

Here, the process in the reduction step S33 is performed using a reduction furnace. As the reduction furnace, for example, a mobile hearth furnace or a rotary hearth furnace can be used. Moreover, when performing temperature holding process S34 which hold | maintains a reduced product in a predetermined | prescribed temperature range, at least the process in reduction process S33 and the process in temperature holding process S34 are performed within one reducing furnace.

In this way, by performing these treatments in one reducing furnace, the temperature in the reducing furnace can be maintained at a high temperature, so that the temperature can be raised or lowered at each treatment in each process. There is no need to do so and the energy cost can be reduced. From this, it is possible to continuously and stably manufacture ferronickel with good quality with high productivity.

(1) Drying process In drying process S31, a drying process is performed with respect to the mixture obtained by mixing raw material powder. The purpose of this drying step S31 is mainly to remove water and crystal water in the mixture.

The mixture obtained in the mixing treatment step S1 contains a lot of moisture and the like, and when rapidly heated to a high temperature such as the reduction temperature during the reduction treatment, the moisture is vaporized, expanded and agglomerated at once. The mixture cracks, and in some cases, ruptures into pieces, making it difficult to perform uniform reduction treatment. Therefore, prior to the reduction treatment, the mixture is subjected to a drying treatment to remove moisture, thereby preventing the destruction of pellets and the like.

It is preferable that the drying process in drying process S31 is performed in the form connected to a reduction furnace. Although it can be considered to provide an area (drying area) for performing a drying process in the reduction furnace, in such a case, the drying process in the drying area becomes rate-limiting, and the process in the reduction process S33 and the temperature holding process are performed. There is a possibility of affecting the processing in S34.

Therefore, it is preferable that the drying process in the drying step S31 is performed in a drying chamber provided outside the reduction furnace and connected to the reduction furnace. Although described in detail later, FIG. 3 shows a configuration example of a rotary hearth furnace 1 which is an example of a reduction furnace and a drying chamber 20 connected to the rotary hearth furnace 1. Thus, by providing the drying chamber 20 outside the rotary hearth furnace 1, the drying chamber can be designed completely different from the steps such as preheating, reduction, and cooling described later, and desirable drying treatment, preheat treatment, reduction treatment, It becomes easy to perform each cooling process. For example, when a lot of moisture remains in the mixture depending on the raw material, the drying process takes time. Therefore, the drying chamber 20 may be designed to have a long overall length, or the mixture in the drying chamber 20 What is necessary is just to design so that a conveyance speed may become slow.

As the drying treatment in the drying chamber 20, for example, the solid content in the mixture can be about 70% by weight and the water content can be about 30% by weight. Further, the drying method is not particularly limited, but can be performed by blowing hot air on the mixture conveyed in the drying chamber 20. Also, the drying temperature is not particularly limited, but from the viewpoint of preventing the reduction reaction from starting, it is preferably 500 ° C. or lower, and it is preferable to uniformly dry at the temperature of 500 ° C. or lower.

Table 2 below shows an example of the composition (parts by weight) of the solid content in the mixture after the drying treatment. The composition of the mixture is not limited to this.

(2) Preheating process In preheating process S32, the mixture after water | moisture content was removed by the drying process in drying process S31 is preheated (preheating).

When the mixture is charged into a reduction furnace and heated to a high reduction temperature, the mixture may break or become powdery due to thermal stress. In addition, the temperature of the mixture may not rise uniformly, causing variations in the reduction reaction, and the quality of the metal produced may vary. For this reason, it is preferable to preheat the mixture to a predetermined temperature after the drying treatment, whereby the destruction of the mixture and variations in the reduction reaction can be suppressed.

The preheating process in the preheating step S32 is preferably performed in a processing chamber provided outside the reduction furnace, similarly to the drying process, and is performed in a preheating chamber connected to the reduction furnace. Is preferred. FIG. 3 shows a configuration example of the preheating chamber 30 connected to the rotary hearth furnace 1 which is an example of the reduction furnace. The preheating chamber 30 is provided outside the rotary hearth furnace 1. It is continuously provided from the drying chamber 20 that performs the drying process. Thus, by performing the pre-heat treatment in the pre-heating chamber 30 provided outside the rotary hearth furnace 1, the temperature in the rotary hearth furnace 1 for performing the reduction process can be maintained at a high temperature, and the rotary furnace The energy required for reheating in the floor furnace 1 can be greatly reduced.

The preheat treatment in the preheating chamber 30 is not particularly limited, but is preferably performed at a preheating temperature of 600 ° C or higher, and more preferably at a preheating temperature of 700 ° C or higher and 1280 ° C or lower. By processing at the preheating temperature in such a range, the energy required for reheating to the reduction temperature in the subsequent reduction process can be greatly reduced.

(3) Reduction step In the reduction step S33, the mixture preheated in the preheating step S32 is reduced at a predetermined reduction temperature. The reduction process in the reduction step S33 can be performed using a reduction furnace such as a mobile hearth furnace or a rotary hearth furnace. And a floor covering material is arrange | positioned on the hearth of this reduction furnace, and the mixture of a nickel oxide ore and a carbonaceous reducing agent is mounted on the floor covering material. As described above, there are four specific modes of reduction. Each aspect will be described below.

(3-1) Reduction Process of First Aspect In the reduction process of the first aspect, at least one material selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite as a flooring material. The mixture of nickel oxide ore and carbonaceous reducing agent is placed on the floor covering material and placed on the hearth of the reduction furnace to reduce the nickel oxide ore.

In this way, by placing a specific flooring material on the hearth of the reduction furnace, placing the mixture on the flooring material and performing a reduction treatment, the reaction between the mixture and the hearth, the mixture and Reaction with the flooring material can be suppressed, and high-quality ferronickel can be produced. Moreover, the obtained reduced product can be recovered effectively. Furthermore, the cost of smelting can be reduced by reusing the flooring material.

The shape of the flooring material is not particularly limited, but for example, it is preferable to use a material composed of particles (flooring material particles). By configuring the flooring material with the flooring material particles, the contact area between the mixture and the flooring material becomes appropriate, and the operability when spreading on the hearth and the handling when recovering from the hearth Also excellent. In addition, when the contact area of a mixture and a flooring material is too large, there exists a possibility that reaction with a mixture and a flooring material may advance. On the other hand, if the contact area is too small, the generated slag or metal may penetrate into the gap between the flooring materials.

When using a material composed of particles as the flooring material, the average flooring material volume ratio is, for example, preferably 3% or more, more preferably 4% or more, and more preferably 5% or more. More preferably. On the other hand, the average floor covering volume ratio is preferably 85% or less, more preferably 82% or less, and further preferably 80% or less. By using a flooring material having an average flooring material volume ratio in such a range, the contact area between the mixture and the flooring material becomes more appropriate.

Here, in the first aspect, the “average flooring material volume ratio” is an average value of the volume ratios (flooring material volume ratios) of arbitrary 300 flooring material particles, according to the following formula (1). Desired. Further, the “floor volume ratio” is the ratio of the volume of the flooring material when the volume of the sphere having the maximum particle length of the flooring material particle is 100%, and the following formula (2) It is calculated by.
Average floor covering volume ratio = total floor covering volume ratio of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere having diameter of maximum particle length of floor covering particles) × 100 (2)

In the first embodiment, the “maximum particle length” in the above formula (2) refers to the longest diameter or side of a specific particle. Specifically, if the particles are elliptical, the maximum particle length is the major axis, and if the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. Therefore, in the first embodiment, “a sphere having a diameter of the maximum particle length of the flooring material particles” refers to a sphere that is in contact with the flooring material particles and encloses the flooring material particles.

FIG. 4 is a schematic diagram of an irregularly shaped particle and a sphere whose diameter is the maximum particle length. In the case of irregular particles, the maximum particle length is determined as shown in FIG. In the first embodiment, the “maximum particle length” can be measured using a metal microscope. On the other hand, the volume of the flooring material particles can be calculated by measuring the weight because the density of the flooring material is known. In this way, 300 randomly selected flooring material particles are measured, the flooring material volume ratio is obtained, and the average flooring material volume ratio is calculated by Equation (1).

When using a material composed of particles as the flooring material, the size of the flooring material particles is not particularly limited, but the average maximum particle length is preferably 10 μm or more, more preferably 15 μm or more. Preferably, it is 20 μm or more. On the other hand, the average maximum particle length is preferably 6000 μm or less, more preferably 5500 μm or less, and even more preferably 5000 μm or less. When the average maximum particle length is a flooring material in such a range, the contact area between the mixture placed on the flooring material and the flooring material becomes appropriate.

Here, in the first embodiment, the “average maximum particle length” refers to the average maximum particle length of 300 randomly selected floor covering particles, and is obtained by the following formula (3).
Average maximum particle length = the sum of the maximum particle lengths of 300 flooring materials / 300 (3)

As bedding material, if used those composed of particles, the specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, 0.002 .mu.m ^-1 or More preferably, it is 0.003 μm ⁻¹ or more. On the other hand, as the specific surface area, for example, is preferably 3.0 [mu] m ^-1 or less, more preferably 2.5 [mu] m ^-1 or less, more preferably 2.0 .mu.m ^-1 or less. By using a flooring material having a specific surface area in such a range, the contact area between the mixture and the flooring material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring apparatus.

The placement ratio of the mixture with respect to the hearth is not particularly limited. For example, it is preferable to arrange the mixture so that it becomes 1% or more of the area of the hearth when viewed in plan, It is more preferable to arrange the mixture so as to achieve the above, and it is even more preferable to arrange the mixture so as to be 2% or more. On the other hand, as an arrangement ratio of the mixture with respect to the hearth, the mixture is preferably arranged so as to be 50% or less of the area of the hearth, and more preferably, the mixture is arranged so as to be 45% or less. It is more preferable to arrange the mixture so as to be not more than%, and it is particularly preferable to arrange the mixture so as to be not more than 40%.

(3-2) In the reduction step of the reduction step a second embodiment of the second aspect, the specific surface area is at 0.001 [mu] m ^-1 or more 3.0 [mu] m ^-1 or less, and an average maximum particle length of more than 15.0 .mu.m 2000 .mu.m The following flooring material (flooring material particles) is placed in the hearth of the reduction furnace, and a mixture of nickel oxide ore and carbonaceous reducing agent is placed on the flooring material to reduce the nickel oxide ore. I do.

In this way, specific flooring particles are placed on the hearth of the reduction furnace, and the mixture is placed on the flooring material and subjected to reduction treatment, whereby the reaction between the mixture and the hearth and the mixture Reaction with the flooring material can be suppressed, high quality ferronickel can be produced, and can be effectively recovered. Moreover, the cost of smelting can be reduced by reusing the flooring material.

Here, what is comprised from particle | grains is used as a floor covering material. The flooring particles have a specific surface area of 0.001 μm ^{−1 to} 3.0 μm ⁻¹ and an average maximum particle length of 15.0 μm to 2000 μm. By using a flooring material composed of particles and having a specific surface area and an average maximum particle length in such ranges, the contact area between the mixture and the flooring material becomes appropriate. In addition, when the contact area of a mixture and a flooring material is too large, there exists a possibility that reaction of both may advance. On the other hand, if the contact area is too small, the generated slag or metal may penetrate into the gap between the flooring materials. The “specific surface area” can be measured using a general specific surface area measuring apparatus.

In the second embodiment, “maximum particle length” refers to the longest diameter or side of a specific particle. Specifically, if the particles are elliptical, the maximum particle length is the major axis, and if the particles are rectangular parallelepiped, the maximum particle length is a diagonal line. FIG. 5 is a schematic diagram showing the maximum particle length of irregular shaped particles. In the case of irregularly shaped particles, the maximum particle length is determined as shown in FIG. This “maximum particle length” can be measured using a metallographic microscope. In the second embodiment, the “average maximum particle length” is an average value of the maximum particle lengths of 300 randomly selected floor covering particles.

The bedding material particles are not particularly limited, but it is preferable to use those composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. By using such a flooring material, the reaction between the mixture and the hearth and the reaction between the mixture and the flooring material can be further suppressed, and high-quality ferronickel can be produced and effectively used. It can be recovered. Moreover, the cost of smelting can be reduced by reusing the flooring material.

The specific surface area of the bedding material particles is preferably 0.002 .mu.m ^-1 or more, and more preferably 0.003 .mu.m ^-1 or more. On the other hand, the specific surface area is preferably 2.5 [mu] m ^-1 or less, more preferably 2.0 .mu.m ^-1 or less. By using a flooring material in which the specific surface area of the flooring material particles is in such a range, the contact area between the mixture placed on the flooring material and the flooring material becomes more appropriate.

The average maximum particle length of the flooring particles is preferably 17.0 μm or more, and more preferably 20.0 μm or more. On the other hand, the average maximum particle length of the flooring particles is preferably 1500 μm or less, more preferably 1200 μm or less, and even more preferably 1000 μm or less. By using a flooring material having an average maximum particle length of the flooring material particles in such a range, the contact area between the mixture placed on the flooring material and the flooring material becomes more appropriate.

The placement ratio of the mixture with respect to the hearth is not particularly limited. For example, it is preferable to arrange the mixture so that it becomes 1% or more of the area of the hearth when viewed in plan, It is more preferable to arrange the mixture so as to achieve the above, and it is even more preferable to arrange the mixture so as to be 2% or more. On the other hand, as an arrangement ratio of the mixture with respect to the hearth, the mixture is preferably arranged so as to be 50% or less of the area of the hearth, and more preferably, the mixture is arranged so as to be 45% or less. It is more preferable to arrange the mixture so as to be not more than%, and it is particularly preferable to arrange the mixture so as to be not more than 40%.

(3-3) Reduction Step of Third Aspect In the third aspect, the floor covering material is composed of particles (floor covering material particles), and the maximum particle length contained in the floor covering material is 50.0 μm or less. A reduction furnace in which the number of flooring particles is 1% or more and 40% or less with respect to the total number of flooring particles contained in the flooring material, and the average maximum particle length is 40.0 μm or more and 1050 μm or less The mixture of nickel oxide ore and carbonaceous reductant is placed on the floor covering material to reduce the nickel oxide ore.

Here, in the third aspect, “maximum particle length” refers to the longest side or diameter of a specific particle. Specifically, for example, if the particle is elliptical, the maximum particle length is a long diameter, and if the particle is a rectangular parallelepiped, the maximum particle length is a diagonal line. FIG. 5 is a schematic diagram showing the maximum particle length of irregular shaped particles. In the case of irregularly shaped particles, the maximum particle length is determined as shown in FIG. This “maximum particle length” can be measured using a metallographic microscope. In the third aspect, the “average maximum particle length” refers to an average value of the maximum particle lengths of 300 randomly selected floor covering particles, and is obtained by the following formula (3).
Average maximum particle length = sum of maximum particle lengths of 300 flooring particles / 300 (3)

In this way, a specific flooring material is placed on the hearth of the reduction furnace, and the mixture placed on the flooring material and the furnace are placed on the flooring material and subjected to reduction treatment. The reaction with the floor and the reaction between the mixture and the flooring material can be suppressed, and high-quality ferronickel can be produced and can be recovered effectively. Moreover, the cost of smelting can be reduced by reusing the flooring material.

As described above, as the flooring material, the number of flooring material particles having a maximum particle length of 50.0 μm or less contained in the flooring material is 1 with respect to the total number of flooring material particles contained in the flooring material. % Or more and 40% or less is used. The number of flooring material particles having a maximum particle length of 50.0 μm or less included in the flooring material is not particularly limited as long as it is included in the above-described range. For example, the total flooring included in the flooring material It is preferably 1.2% or more, more preferably 1.5% or more, still more preferably 1.7% or more, and particularly preferably 2% or more with respect to the number of material particles. preferable. On the other hand, the number of flooring material particles having a maximum particle length of 50.0 μm or less contained in the flooring material is, for example, 37% or less with respect to the total number of flooring material particles contained in the flooring material. It is preferably 35% or less, more preferably 32% or less, and particularly preferably 30% or less.

Moreover, as described above, as the flooring material, one having an average maximum particle length of 40.0 μm or more and 1050 μm or less is used. The average maximum particle length is preferably 42.0 μm or more, more preferably 45.0 μm or more, further preferably 47.0 μm or more, and particularly preferably 50.0 μm or more. . On the other hand, the average maximum particle length is preferably 1030 μm or less, and more preferably 1000 μm or less.

The specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, more preferably 0.002 .mu.m ^-1 or more, is 0.003 .mu.m ^-1 or More preferably. On the other hand, as the specific surface area, for example, is preferably 3.0 [mu] m ^-1 or less, more preferably 2.5 [mu] m ^-1 or less, more preferably 2.0 .mu.m ^-1 or less. By using a flooring material having a specific surface area in such a range, the contact area between the mixture and the flooring material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring apparatus.

The floor covering material is not particularly limited, but it is preferable to use a material composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement or mullite. By using such a flooring material, the reaction between the mixture and the hearth and the reaction between the mixture and the flooring material can be further suppressed, and high-quality ferronickel can be produced. Further, the flooring material can be reused, and as a result, the cost of smelting can be reduced.

The placement ratio of the mixture with respect to the hearth is not particularly limited. For example, it is preferable to arrange the mixture so that it becomes 1% or more of the area of the hearth when viewed in plan, It is more preferable to arrange the mixture so as to achieve the above, and it is even more preferable to arrange the mixture so as to be 2% or more. On the other hand, as an arrangement ratio of the mixture with respect to the hearth, the mixture is preferably arranged so as to be 50% or less of the area of the hearth, and more preferably, the mixture is arranged so as to be 45% or less. It is more preferable to arrange the mixture so as to be not more than%, and it is particularly preferable to arrange the mixture so as to be not more than 40%.

(3-4) Reduction process of the fourth aspect In the fourth aspect, the floor covering material is laid on the hearth of the reduction furnace, and when the hearth floor is viewed in plan on the floor covering material, the area of the hearth floor is reduced. The mixture is arranged so as to be 50% or less, and nickel oxide ore is reduced.

In this way, the reaction between the mixture and the hearth and the reaction between the mixture and the flooring material are suppressed by placing the mixture on the flooring material at a specific placement ratio (placement area ratio) and performing a reduction treatment. High quality ferronickel can be produced and can be recovered effectively. Moreover, the cost of smelting can be reduced by reusing the flooring material.

As described above, the mixture is arranged on the hearth of the reduction furnace so that the area of the hearth becomes 50% or less when viewed in plan. By arranging the mixture on the hearth of the reduction furnace so as to be 50% of the area of the hearth in plan view, the contact area between the mixture and the flooring material becomes appropriate. In addition, when the contact area of a mixture and a flooring material is too large, there exists a possibility that reaction of both may advance. On the other hand, if the contact area is too small, the generated slag or metal may penetrate into the gap between the flooring materials.

Moreover, as an arrangement ratio (arrangement area ratio) of the mixture with respect to the hearth, for example, the mixture is preferably arranged so as to be 3% or more of the area of the hearth, and the mixture is arranged so as to be 5% or more. It is more preferable. On the other hand, in the hearth of the reduction furnace, the mixture is preferably arranged to be 45% or less, more preferably the mixture is arranged to be 42% or less, and the mixture is made to be 40% or less. It is further preferable to arrange By arranging the mixture in such an area with respect to the hearth, the contact area between the mixture and the flooring material becomes more appropriate.

Here, as described above, the flooring material is laid on the hearth. By this floor covering material, the reduction treatment is performed without the mixture and the hearth contacting each other. FIG. 6 is a schematic diagram showing an installation example of a spherical mixture with respect to a flooring material. FIG. 7 is a schematic diagram showing an installation example of a rectangular parallelepiped mixture with respect to the flooring material. As shown in FIG.6 and FIG.7, it is preferable to install the mixture so that at least a part thereof is embedded on the flooring material. By installing the mixture in this way, the mixture can be stably installed on the flooring material, and even when the reduction reaction proceeds while the hearth moves, the reactivity varies due to rolling or moving. Can be prevented from occurring. Further, the contact area between the mixture and the flooring material can be made constant within a certain range, and the reactivity is difficult to vary.

The shape of the flooring material is not particularly limited, but it is preferable to use particles composed of particles (flooring material particles). By using particles composed of particles as the flooring material, the contact area between the mixture and the flooring material becomes more appropriate, and the operability when laying on the hearth and when recovering from the hearth Excellent handleability.

As bedding material, if used those composed of particles, the specific surface area of the bedding material particles is not particularly limited, for example, is preferably 0.001 [mu] m ^-1 or more, 0.002 .mu.m ^-1 or More preferably, it is 0.003 μm ⁻¹ or more. On the other hand, as the specific surface area, for example, is preferably 3.0 [mu] m ^-1 or less, more preferably 2.5 [mu] m ^-1 or less, more preferably 2.0 .mu.m ^-1 or less. By using a flooring material having a specific surface area in such a range, the contact area between the mixture and the flooring material becomes more appropriate. The “specific surface area” can be measured using a general specific surface area measuring apparatus.

In addition, when using what is composed of particles as the flooring material, the size of the flooring material particles is not particularly limited, for example, the average maximum particle length is preferably 20.0 μm or more and 1000 μm or less, More preferably, it is 50.0 μm or more and 700 μm or less. When the average maximum particle length of the flooring material is in such a range, the contact area between the mixture and the flooring material becomes more appropriate.

Here, in the fourth aspect, “maximum particle length” refers to the longest side or diameter of a specific particle. Specifically, for example, if the particle is elliptical, the maximum particle length is a long diameter, and if the particle is a rectangular parallelepiped, the maximum particle length is a diagonal line. This “maximum particle length” can be measured using a metallographic microscope. In the fourth embodiment, the “average maximum particle length” is an average value of the maximum particle lengths of 100 randomly selected flooring material particles.

Further, the floor covering material is not particularly limited, but it is preferable to use a material composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. By using such a flooring material, the reaction between the mixture and the hearth and the reaction between the mixture and the flooring material can be further suppressed, and high-quality ferronickel can be produced. Further, the flooring material can be reused, and as a result, the cost of smelting can be reduced.

(3-5) Other Conditions Hereinafter, reduction conditions common to the reduction processes of the first to fourth aspects and reduction furnaces used in common will be described.

In the reduction treatment using a reduction furnace, nickel oxide, which is a metal oxide contained in nickel oxide ore, is reduced as completely as possible and preferentially to iron, while raw powder together with nickel oxide ore. It is preferable to carry out so-called partial reduction, in which iron oxide derived from iron ore and the like mixed is partially reduced to obtain ferronickel having a target nickel quality.

Specifically, the reduction temperature is not particularly limited, but is preferably in the range of 1200 ° C to 1450 ° C, and more preferably in the range of 1300 ° C to 1400 ° C. By reducing in such a temperature range, a reduction reaction can be caused uniformly and a metal (ferronickel metal) with suppressed quality variation can be generated. More preferably, by performing reduction at a reduction temperature in the range of 1300 ° C. or higher and 1400 ° C. or lower, a desired reduction reaction can be caused in a relatively short time.

Usually, when reduction is performed at a high temperature of 1300 ° C. or higher using a reduction furnace having a metal hearth, the slag or metal generated from the mixture may react with the hearth and damage the hearth in a short time. . Moreover, the metal component of a hearth etc. may mix in the mixture or the reduced metal, and there exists a possibility of causing the fall of the quality of the metal obtained. Furthermore, when usual floor covering materials, such as coal and coke, are used, there exists a possibility that the slag and metal produced | generated from the mixture may react with such floor covering materials. Such a reaction is acceptable to a slight extent, but the flooring material may be altered and cannot be reused.

During the reduction treatment, the internal temperature of the reduction chamber in the reduction furnace is raised until the reduction temperature in the above-described range, and the temperature is maintained after the temperature rise.

[Rotating hearth furnace]
As described above, as the reduction furnace, for example, a mobile hearth furnace or a rotary hearth furnace can be used. According to such a reduction furnace, the metal contained in the metal oxide can be effectively metalized and an efficient smelting treatment can be performed. Hereinafter, the configuration of a rotary hearth furnace will be described with reference to FIG. 3 as an example of a reduction furnace.

FIG. 3 is a diagram (plan view) showing a configuration example of a rotary hearth furnace in which the hearth rotates. As shown in FIG. 3, the rotary hearth furnace 1 has a region 10 in which the hearth rotates, and the region 10 is divided into four, and each constitutes a processing chamber (10a, 10b, 10c, 10d). Yes. Specifically, in the rotary hearth furnace 1, for example, all four treatment chambers with reference numerals “10a” to “10d” may be reduction chambers for performing reduction treatment. Further, when the temperature holding step S34 described later is executed after the processing in the reduction step S33, for example, the processing chambers “10a”, “10b”, and “10c” are set as the reduction chamber, and the processing chamber “10d” is held at the temperature. It can be set as the temperature holding chamber which performs the process in process S34. Further, when the cooling step S5 described later is performed after the processing in the reduction step S33, for example, the processing chambers “10a”, “10b”, and “10c” are set as the reduction chamber, and the processing chamber “10d” is set as the cooling step S5. It can be set as the temperature holding chamber which performs the process in.

It is preferable that each process, that is, between each processing chamber, be partitioned by a partition wall in order to strictly control the reaction temperature and suppress energy loss. Thus, according to the rotary hearth furnace having a structure capable of partitioning the sub-size of each process, the energy loss is suppressed between the process in the reduction process S33 and the process in the temperature holding process S34, as will be described later. However, the same rotary hearth furnace can be used. However, if the partition wall is of a fixed type, it may be difficult to transport between processes, and particularly to charge and discharge the rotary hearth furnace. It is preferable to have a structure that can be opened and closed to the extent that it does not interfere with.

Note that the number of processing chambers formed by dividing the area 10 in which the hearth rotates is not limited to four illustrated in FIG. Further, the number of reduction chambers and the number of temperature holding chambers are not limited to the above-described example, and can be appropriately set according to the processing time and the like.

As described above, the rotary hearth furnace 1 includes a hearth that rotates and moves on a plane, and the hearth on which the mixture is placed rotates and moves at a predetermined speed, so that each processing chamber (10a, 10a, 10b, 10c, 10d), and processing is performed at the time of the passage. In addition, while the arrow on the rotary hearth furnace 1 in FIG. 3 shows the rotation direction of a hearth, it shows the moving direction of a processed material (mixture).

Further, the rotary hearth furnace 1 is connected to a drying chamber 20 provided outside the furnace and a preheating chamber 30, and as described above, after the drying treatment is performed on the mixture in the drying chamber 20. The dried mixture moves to the preheating chamber 30 and is preheated, and the preheated mixture is sequentially transferred into the rotary hearth furnace 1. In addition, the rotary hearth furnace 1 is connected to a cooling chamber 40 provided outside the furnace, and the reduced product obtained through the reduction chamber or the temperature holding chamber (10d) is cooled in the cooling chamber 40. (Cooling step S35 described later).

(4) Temperature holding process You may make it perform the temperature holding process S34 which hold | maintains the reduced material obtained through reduction process S33 on a predetermined high temperature condition in a rotary hearth furnace. In this way, the reduced product obtained by the reduction treatment at the predetermined reduction temperature in the reduction step S33 is not immediately cooled, but is held in a high-temperature atmosphere, so that the metal component generated in the reduced product is retained. It can be settled and coarsened.

In the temperature holding step S34, even when nickel metal or slag is generated by a reduction reaction by using a flooring material, it does not react with the hearth, and the slag does not penetrate or stick to the hearth.

When the metal component in the reduced product is small in the state obtained by the reduction treatment, for example, when it is a bulk metal of about 200 μm or less, the metal and slag are separated in the subsequent separation step S4. Will become difficult. For this reason, if necessary, the reduced product is kept at a high temperature, so that the metal having a specific gravity larger than that of the slag in the reduced product is settled and aggregated to coarsen the metal.

In addition, when the metal is coarsened to a level at which there is no problem in manufacturing due to the reduction process in the reduction step S33, it is not particularly necessary to provide the temperature holding step S34.

Specifically, the reduced product holding temperature in the temperature holding step S34 is preferably in the high temperature range of 1300 ° C to 1500 ° C. By holding the reduced product at a high temperature in such a range, the metal component in the reduced product can be efficiently precipitated to form a coarse metal. When the holding temperature is lower than 1300 ° C., a large part of the reduced product becomes a solid phase, so that it takes time even when the metal component does not settle or settles. On the other hand, when the holding temperature exceeds 1500 ° C., the reaction between the obtained reduced product and the flooring material proceeds and the reduced product may not be recovered, and the furnace may be damaged. .

Here, the treatment in the temperature holding step S34 is performed continuously following the reduction treatment in the rotary hearth furnace 1 used in the reduction step S33. That is, as described with reference to FIG. 3, in the rotary hearth furnace 1, for example, the processing chambers “10a”, “10b”, and “10c” are used as the reduction chambers, and the processing chamber “10d” is used in the temperature holding step S34. A temperature holding chamber for processing is used, and the reduced product obtained through the reduction chambers (10a, 10b, 10c) is held in a predetermined temperature range in the temperature holding chamber (10d).

Thus, the metal component in the reduction product is efficiently settled by continuously performing the process of maintaining the reduction product obtained through the reduction treatment at a predetermined temperature using the rotary hearth furnace 1. Can be coarsened. In addition, the process in the reduction process S33 and the process in the temperature holding process S34 are continuously performed using the rotary hearth furnace 1 instead of separate furnaces, so that heat loss between the processes is reduced and efficient. Enable operation.

(5) Cooling step In the cooling step S35, the reduction product obtained through the reduction step S33 or the reduction product after being held at a high temperature for a predetermined time in the temperature holding step S34 is separated and recovered in the subsequent separation step S4. Cool down to a temperature where you can.

Since the cooling step S35 is a step of cooling the reduction product obtained as described above, it is preferably performed in a cooling chamber connected to the outside of the rotary hearth furnace 1. FIG. 3 shows a configuration example of the cooling chamber 40 connected to the rotary hearth furnace 1. The cooling chamber 40 is provided outside the rotary hearth furnace 1. Thus, by performing the cooling process in the cooling chamber 40 provided outside the rotary hearth furnace 1, a decrease in the internal temperature of the rotary hearth furnace 1 can be prevented and energy loss can be suppressed. it can. This enables efficient production of ferronickel.

The temperature in the cooling step S35 (hereinafter also referred to as “recovery temperature”) is a temperature at which the reduced product can be handled substantially as a solid, and is preferably as high as possible. By making the temperature at the time of recovery as high as possible, energy loss can be reduced even when the hearth of the rotary hearth furnace 1 that rotates and moves back to the connection point with the preheating chamber 30 that executes the preheating step S32, and reheating is possible. The required energy can be further saved.

Specifically, the recovery temperature is preferably 600 ° C. or higher. Thus, by making the temperature at the time of recovery high, the energy required for reheating can be greatly reduced, and efficient smelting treatment can be performed at low cost. Moreover, by reducing the temperature difference in the rotary hearth furnace 1, the thermal stress applied to the hearth, the furnace wall, etc. can be reduced, and the life of the rotary hearth furnace 1 can be greatly extended. In addition, problems during operation can be greatly reduced.

<2-4. Separation process>
Separation process S4 isolate | separates and collect | recovers a metal (ferronickel metal) from the reduced material produced | generated in reduction process process S3. Specifically, in the separation step S4, a metal phase obtained from a mixture (reduced product) of a metal phase (metal solid phase) and a slag phase (slag solid phase) obtained by subjecting the mixture to reduction heat treatment is used. Is separated and recovered.

As a method for separating the metal phase and the slag phase from the mixture of the metal phase and the slag phase obtained as a solid, for example, in addition to removing unnecessary materials by sieving, separation by specific gravity, separation by magnetic force, etc. Can be used. In addition, the obtained metal phase and slag phase can be easily separated because of poor wettability, and for example, when a large mixture is dropped with a predetermined drop, or when sieving By giving an impact such as giving a predetermined vibration, the metal phase and the slag phase can be easily separated from the mixture.

Thus, by separating the metal phase and the slag phase, the metal phase can be recovered and made into a ferronickel product.

Hereinafter, although an example of the present invention is shown and explained more concretely, the present invention is not limited to the following example at all.

[Example 1]
(Mixing process)
Mix nickel oxide ore as raw material oxide ore, iron ore, silica sand and limestone as flux components, binder and coal as carbonaceous reducing agent using a mixer while adding appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total value of chemical equivalents required for reducing nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or deficiency is 100%. In an amount corresponding to.

The mixture obtained by mixing with a mixer was kneaded with a twin-screw kneader.

(Reduction input pretreatment process)
Next, the mixture sample obtained by kneading was formed into spherical pellets of φ18 ± 1.5 mm using a pan-type granulator.

(Reduction treatment process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, reduction treatment was performed by changing the treatment conditions using the mixture sample. As shown in FIG. 3, the rotary hearth furnace 1 includes a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously to the drying chamber 20, and a processing chamber in the furnace, as shown in FIG. 3. What connected with the cooling chamber 40 which cools the reduced material obtained through 10a-10d was used. In Example 1, the processing chamber 10d was used as a cooling chamber.

Specifically, the pellet sample was placed in the drying chamber 20 connected to the outside of the rotary hearth furnace 1 and dried. In the drying process, hot air of 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere that does not substantially contain oxygen so that the pellets have a solid content of about 70% by weight and water content of about 30% by weight. Went by. Table 3 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 continuously provided in the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C. or higher and 1280 ° C. or lower, so Heat treatment was performed.

Subsequently, the pellets after the pre-heat treatment were transferred into the rotary hearth furnace 1 and subjected to reduction treatment and temperature holding treatment. Specifically, as the rotary hearth furnace 1, the region 10 in which the hearth rotates and moves is divided into four, and four processing chambers are provided, and all the four processing chambers 10a to 10d perform reduction processing. The room.

The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1 and quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere. The reductant was recovered from the rotary hearth furnace 1 in a form in which the reductant was transferred to the cooling chamber 40, and the reductant was recovered along with a guide installed in the cooling chamber 40.

In Examples 1-1 to 1-48, a flooring material composed of particles was laid on the hearth, and a pellet of the mixture was placed thereon to perform a reduction treatment. In Comparative Examples 1-1 to 1-3, the reduction treatment was performed by placing the pellets directly on the metal hearth. Tables 4 to 6 below show the conditions for the reduction treatment in the reduction steps of Examples 1 to 48 and Comparative Examples 1-1 to 1-3.

The average maximum particle length was obtained from the average value of the maximum particle lengths of 300 floor covering particles randomly selected and measured using a metal microscope. Further, the volume of the flooring material is determined by measuring the total weight of 300 particles used to obtain the average value of the maximum particle length and dividing by the density of the material constituting the flooring material. Asked.

After the reduction treatment, the pellets, floor covering material, and hearth were visually confirmed to confirm the presence or absence of mutual reaction. The results are shown in Tables 4-6 below.

Further, the nickel quality of the sample taken out was analyzed with an ICP emission spectroscopic analyzer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following formula (4), and the nickel content in the metal was calculated by the following formula (5). Tables 4 to 6 below show the nickel metal ratio and the nickel content in the metal of the samples obtained in Examples 1-1 to 1-48 and Comparative Examples 1-1 to 1-3.
Nickel metalization rate = amount of Ni metalized in the reduction treatment input pellet / (total amount of Ni in the reduction treatment input pellet) × 100 (%) (4)
Nickel content in metal = amount of Ni metalized in the reduction treatment input pellet / (total amount of metal Ni and Fe in the reduction treatment input pellet) × 100 (%) (5)

As described above, in Examples 1-1 to 1-48, the predetermined flooring material was used, so that the flooring material and the hearth did not react with the sample, and as a result, high quality with less impurities and the like. Of ferronickel could be produced. Further, since the flooring material can be reused, it can be realized at a low cost. Furthermore, since the metal component is large, the metal is likely to become coarse.

On the other hand, in Comparative Examples 1-1 to 1-3, the sample reacted with the hearth and mixed, and the metal could not be recovered effectively.

[Example 2]
(Mixing process)
Mix nickel oxide ore as raw material oxide ore, iron ore, silica sand and limestone as flux components, binder and coal as carbonaceous reducing agent using a mixer while adding appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 36% in terms of carbon amount when the total value of chemical equivalents required to reduce nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or deficiency is 100%. In an amount corresponding to.

The mixture obtained by mixing with a mixer was kneaded with a twin-screw kneader.

(Reduction input pretreatment process)
Next, the mixture sample obtained by kneading was molded into spherical pellets of φ16 ± 1.5 mm using a pan-type granulator.

(Reduction treatment process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, the flooring material composed of particles is laid on the hearth of the rotary hearth furnace 1, and the processing conditions are changed using the mixture sample. Reduction treatment was performed. As shown in FIG. 3, the rotary hearth furnace 1 includes a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously to the drying chamber 20, and a processing chamber in the furnace, as shown in FIG. 3. What connected with the cooling chamber 40 which cools the reduced material obtained through 10a-10d was used. In Example 2, the processing chamber 10d was used as a cooling chamber.

Specifically, the pellet sample was placed in the drying chamber 20 connected to the outside of the rotary hearth furnace 1 and dried. In the drying process, hot air of 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere that does not substantially contain oxygen so that the pellets have a solid content of about 70% by weight and water content of about 30% by weight. Went by. Table 7 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 continuously provided in the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C. or higher and 1280 ° C. or lower, so Heat treatment was performed.

Subsequently, the pellets after the pre-heat treatment were transferred into the rotary hearth furnace 1 and subjected to reduction treatment and temperature holding treatment. Specifically, as the rotary hearth furnace 1, the region 10 in which the hearth rotates and moves is divided into four, and four processing chambers are provided, and all the four processing chambers 10a to 10d perform reduction processing. The room.

The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1 and quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere. The reductant was recovered from the rotary hearth furnace 1 in a form in which the reductant was transferred to the cooling chamber 40, and the reductant was recovered along with a guide installed in the cooling chamber 40.

In Tables 8 to 10 below, in Examples 2-1 to 2-48 and Comparative Examples 2-1 to 2-12, the material of the flooring material, the specific surface area of the flooring material, the average maximum particle length of the flooring material, The reduction temperature and reduction time are shown.

The specific surface area of the flooring material was measured using a Shimadzu Corporation specific surface area measuring device (Flowsorb III2305). The average maximum particle length was determined from the average value of the maximum particle lengths of 300 floor covering particles randomly selected and measured using a metal microscope. Further, the volume of the flooring material is determined by measuring the total weight of 300 particles used to obtain the average value of the maximum particle length and dividing by the density of the material constituting the flooring material. Asked.

Further, the nickel quality of the sample taken out was analyzed with an ICP emission spectroscopic analyzer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following formula (4), and the nickel content in the metal was calculated by the following formula (5).
Nickel metalization rate = amount of Ni metalized in the reduction treatment input pellet / (total amount of Ni in the reduction treatment input pellet) × 100 (%) (4)
Nickel content in metal = amount of Ni metalized in the reduction treatment input pellet / (total amount of metal Ni and Fe in the reduction treatment input pellet) × 100 (%) (5)

Further, each collected sample was pulverized by wet processing, and then metal was collected by magnetic sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the recovered Ni amount. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

Tables 8 to 10 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery rate of the samples obtained in Examples 2-1 to 2-48 and Comparative Examples 2-1 to 2-12.

As described above, in Examples 2-1 to 2-48, by using a predetermined floor covering material, uniform and stable reduction can be performed. As a result, the Ni metalization rate and the recovery rate are high, High quality ferronickel could be produced for Ni. Moreover, a floor covering material can be used continuously and nickel can be manufactured cheaply. Further, since the Ni content ratio metal component is large, the metal tends to be coarsened.

Example 3
(Mixing process)
Mix nickel oxide ore as raw material oxide ore, iron ore, silica sand and limestone as flux components, binder and coal as carbonaceous reducing agent using a mixer while adding appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total value of chemical equivalents required for reducing nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or deficiency is 100%. In an amount corresponding to.

The mixture obtained by mixing with a mixer was kneaded with a twin-screw kneader.

(Reduction input pretreatment process)
Examples 3-1 to 3-12, Examples 3-25 to 3-36, Comparative Example 3-1, Comparative Example 3-2, Comparative Example 3-5, and Comparative Example 3-6 were obtained by kneading. The obtained mixture sample was formed into spherical pellets of φ16 ± 1.5 mm using a pan granulator.

For Examples 3-13 to 3-24, Examples 3-37 to 3-48, Comparative Example 3-3, Comparative Example 3-4, Comparative Example 3-7, and Comparative Example 3-8, 15 mm long × horizontal The mixture was molded into a mold so as to have a rectangular parallelepiped shape of 15 mm × 10 mm in height.

(Reduction treatment process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, the flooring material composed of particles is laid on the hearth of the rotary hearth furnace 1, and the processing conditions are changed using the mixture sample. Reduction treatment was performed. As shown in FIG. 3, the rotary hearth furnace 1 includes a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously to the drying chamber 20, and a processing chamber in the furnace, as shown in FIG. 3. What connected with the cooling chamber 40 which cools the reduced material obtained through 10a-10d was used. In Example 3, the processing chamber 10d was used as a cooling chamber.

Specifically, the pellet sample was placed in the drying chamber 20 connected to the outside of the rotary hearth furnace 1 and dried. In the drying process, hot air of 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere that does not substantially contain oxygen so that the pellets have a solid content of about 70% by weight and water content of about 30% by weight. Went by. Table 11 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 continuously provided in the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C. or higher and 1280 ° C. or lower, so Heat treatment was performed.

Subsequently, the pellets after the pre-heat treatment were transferred into the rotary hearth furnace 1 and subjected to reduction treatment and temperature holding treatment. Specifically, as the rotary hearth furnace 1, the region 10 in which the hearth rotates and moves is divided into four, and four processing chambers are provided, and all the four processing chambers 10a to 10d perform reduction processing. The room.

The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1 and quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere. The reductant was recovered from the rotary hearth furnace 1 in a form in which the reductant was transferred to the cooling chamber 40, and the reductant was recovered along with a guide installed in the cooling chamber 40.

In Tables 12 to 14 below, the materials of the flooring material, the ratio of the number of particles having a maximum particle length of 50.0 μm or less, and the flooring in Examples 3-1 to 3-48 and Comparative Examples 3-1 to 3-12 The average maximum particle length, reduction temperature and reduction time of the material are shown.

The specific surface area of the flooring material was measured using a Shimadzu Corporation specific surface area measuring device (Flowsorb III2305). For the average value of the maximum particle length, an average value of the maximum particle lengths of 300 flooring material particles randomly selected and measured using a metal microscope was obtained.

Further, the nickel quality of the sample taken out was analyzed with an ICP emission spectroscopic analyzer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following formula (4), and the nickel content in the metal was calculated by the following formula (5).
Nickel metalization rate = amount of Ni metalized in the reduction treatment input pellet / (total amount of Ni in the reduction treatment input pellet) × 100 (%) (4)
Nickel content in metal = amount of Ni metalized in the reduction treatment input pellet / (total amount of metal Ni and Fe in the reduction treatment input pellet) × 100 (%) (5)

Further, each collected sample was pulverized by wet processing, and then metal was collected by magnetic sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the recovered Ni amount. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

Tables 12 to 14 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery rate of the samples obtained in Examples 3-1 to 3-48 and Comparative Examples 3-1 to 3-12.

As described above, in Examples 3-1 to 3-48, by using a predetermined floor covering material, uniform and stable reduction can be performed. As a result, the Ni metalization rate and the recovery rate are high, High quality ferronickel could be produced for Ni. Moreover, a floor covering material can be used continuously and nickel can be manufactured cheaply. Further, since the Ni content ratio metal component is large, the metal tends to be coarsened.

Example 4
(Mixing process)
Mix nickel oxide ore as raw material oxide ore, iron ore, silica sand and limestone as flux components, binder and coal as carbonaceous reducing agent using a mixer while adding appropriate amount of water. To obtain a mixture. The carbonaceous reducing agent is 30% in terms of carbon when the total value of chemical equivalents required for reducing nickel oxide and iron oxide (Fe ₂ O ₃ ) to metal without excess or deficiency is 100%. In an amount corresponding to.

The mixture obtained by mixing with a mixer was kneaded with a twin-screw kneader.

(Reduction input pretreatment process)
Examples 4-1 to 4-12, Examples 4-25 to 4-36, Comparative Example 4-1, Comparative Example 4-2, Comparative Example 4-5 and Comparative Example 4-6 were obtained by kneading. The obtained mixture sample was formed into spherical pellets with a diameter of 15 ± 1.5 mm using a bread granulator.

For Examples 4-13 to 4-24, Examples 4-37 to 4-48, Comparative Example 4-3, Comparative Example 4-4, Comparative Example 4-7, and Comparative Example 4-8, 15 mm long × horizontal The mixture sample was molded into a mold so as to have a rectangular parallelepiped shape of 15 mm × 10 mm in height.

(Reduction treatment process)
Next, using the rotary hearth furnace 1 illustrated in FIG. 3, reduction treatment was performed by changing the treatment conditions using the mixture sample. As shown in FIG. 3, the rotary hearth furnace 1 includes a drying chamber 20 for drying pellets, a preheating chamber 30 provided continuously to the drying chamber 20, and a processing chamber in the furnace, as shown in FIG. 3. What connected with the cooling chamber 40 which cools the reduced material obtained through 10a-10d was used. In Example 4, the processing chamber 10d was used as a cooling chamber.

Specifically, the pellet sample was placed in the drying chamber 20 connected to the outside of the rotary hearth furnace 1 and dried. In the drying process, hot air of 250 ° C. to 350 ° C. is blown onto the pellets in a nitrogen atmosphere that does not substantially contain oxygen so that the pellets have a solid content of about 70% by weight and water content of about 30% by weight. Went by. Table 15 below shows the solid content composition (excluding carbon) of the pellets after the drying treatment.

Subsequently, the pellets after the drying treatment are transferred to a preheating chamber 30 continuously provided in the drying chamber 20, and the temperature in the preheating chamber 30 is maintained in a range of 700 ° C. or higher and 1280 ° C. or lower, so Heat treatment was performed.

Subsequently, the pellets after the pre-heat treatment were transferred into the rotary hearth furnace 1 and subjected to reduction treatment and temperature holding treatment. Specifically, as the rotary hearth furnace 1, the region 10 in which the hearth rotates and moves is divided into four, and four processing chambers are provided, and all the four processing chambers 10a to 10d perform reduction processing. The room.

The reduced product obtained through the reduction treatment was transferred to a cooling chamber connected to the rotary hearth furnace 1 and quickly cooled to room temperature while flowing nitrogen and taken out into the atmosphere. The reductant was recovered from the rotary hearth furnace 1 in a form in which the reductant was transferred to the cooling chamber 40, and the reductant was recovered along with a guide installed in the cooling chamber 40.

In Tables 16 to 18 below, in Examples 4-1 to 4-48 and Comparative Examples 4-1 to 4-12, the material of the floor covering material, the shape of the floor covering material, the arrangement area ratio of the mixture with respect to the hearth, and the reduction Temperature and reduction time are indicated.

Further, the nickel quality of the sample taken out was analyzed with an ICP emission spectroscopic analyzer (SHIMAZU S-8100), and the nickel metal ratio and the nickel content in the metal were calculated. The nickel metal ratio was calculated by the following formula (4), and the nickel content in the metal was calculated by the following formula (5).
Nickel metalization rate = amount of Ni metalized in the reduction treatment input pellet / (total amount of Ni in the reduction treatment input pellet) × 100 (%) (4)
Nickel content in metal = amount of Ni metalized in the reduction treatment input pellet / (total amount of metal Ni and Fe in the reduction treatment input pellet) × 100 (%) (5)

Further, each collected sample was pulverized by wet processing, and then metal was collected by magnetic sorting. Then, the Ni metal recovery rate was calculated from the input amount of nickel oxide ore, the Ni content ratio therein, and the recovered Ni amount. The Ni metal recovery rate was determined by the following equation (6).
Ni metal recovery rate = {recovered Ni amount / (input amount of nickel oxide ore × Ni content ratio)} × 100 (6)

Tables 16 to 18 below show the nickel metal ratio, the nickel content in the metal, and the nickel recovery rate of the samples obtained in Examples 4-1 to 4-48 and Comparative Examples 4-1 to 4-8.

As described above, in Examples 4-1 to 4-48, the mixture was arranged at a specific ratio with respect to the hearth, so that uniform and stable reduction could be performed. As a result, the Ni metalization rate and the recovery were achieved. The rate was high and it was possible to produce high quality ferronickel for Ni. Moreover, a floor covering material can be used continuously and nickel can be manufactured cheaply. Further, since the Ni content ratio metal component is large, the metal tends to be coarsened.

1 rotary hearth furnace 10 region 10a, 10b, 10c, 10d processing chamber (reduction chamber, temperature holding chamber, cooling chamber)
20 Drying room 30 Preheating room 40 Cooling room 51 Mixture (spherical)
52 Flooring material 61 Mixture (cubic)
62 Flooring material

Claims (11)

A metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
A metal oxide smelting method in which the mixture is heated and reduced on a floor covering composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement and mullite. The flooring material is composed of particles of the material (flooring material particles),
The method for smelting a metal oxide according to claim 1, wherein an average flooring material volume ratio obtained from the following formulas (1) and (2) is 3% or more and 85% or less.
Average floor covering volume ratio = total floor covering volume ratio of 300 floor covering particles / 300 (1)
Floor covering volume ratio = (volume of floor covering particles / volume of sphere having diameter of maximum particle length of floor covering particles) × 100 (2) The flooring material is composed of particles of the material (flooring material particles),
The average maximum particle length calculated | required from following formula (3) is 10 micrometers or more and 6000 micrometers or less. The smelting method of the metal oxide of Claim 1 or 2.
Average maximum particle length = sum of maximum particle lengths of 300 flooring particles / 300 (3) A metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
The specific surface area is at 0.001 [mu] m ^-1 or more 3.0 [mu] m ^-1 or less, and an average maximum particle length is bedding material onto comprised particles less 2000μm or more 15.0 .mu.m (bedding material particles), the A method for smelting a metal oxide, wherein the mixture is heated and reduced. The metal oxide smelting method according to claim 4, wherein the flooring material particles are composed of one or more materials selected from alumina, alumina cement, magnesia, magnesia cement, zirconia, zirconia cement, and mullite. A metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
Laying flooring material on the hearth of the reduction furnace,
The flooring material is composed of particles (flooring material particles), and the total number of flooring material particles having a maximum particle length of 50.0 μm or less contained in the flooring material is included in the flooring material. 1% to 40% of the number of particles,
The flooring material particles have a mean maximum particle length of 40.0 μm or more and 1050 μm or less determined by the following formula (3).
Average maximum particle length = sum of maximum particle lengths of 300 flooring particles / 300 (3) A metal oxide smelting method for reducing a mixture obtained by mixing a metal oxide and a carbonaceous reducing agent in a reduction furnace,
Laying flooring material on the hearth of the reduction furnace,
A method for smelting metal oxide, wherein the mixture is placed on the floor covering material so as to be 50% or less of the area of the hearth when viewed in plan, and heated and reduced. The metal oxide smelting method according to claim 7, wherein the mixture has a spherical shape, a cubic shape, or a rectangular parallelepiped shape. The method for smelting a metal oxide according to any one of claims 1 to 8, wherein the reduction temperature is from 1200C to 1450C. The metal oxide smelting method according to any one of claims 1 to 9, wherein the metal oxide is nickel oxide ore. The metal oxide smelting method according to any one of claims 1 to 10, wherein the reduced product contains ferronickel.

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