WO2024154733A1 - Electrolytic product collecting method and system - Google Patents

Abstract

According to the present invention, an electrolytic product collecting method and an electrolytic product collecting system involve: leaching, with a sodium hydroxide aqueous solution (2), a zinc-containing substance derived from zinc-containing dust (1) to obtain a zinc-containing sodium hydroxide aqueous solution (3); performing electrolysis by using an electrolysis device (E) comprising an electrolysis tank (30) that accommodates an electrolysis bath (32) using an anode (10), a cathode (20) that faces the anode (10) and that is made of pure magnesium or a magnesium alloy, and the zinc-containing sodium hydroxide aqueous solution (3); and, in the electrolysis tank (30), bringing contact members (44), sequentially at a prescribed time interval, into contact with a plurality of portions of a zinc electrodeposition substance (4) obtained as an electrolytic product in an electrolysis step (102), to thereby peel off the zinc electrodeposition substance (4) from the cathode (20).

Description

Electrolytic product collection method and system

The present invention relates to a method and system for extracting electrolytic products, and in particular to a method and system for extracting electrolytic products using primary or secondary dust such as blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust, as well as zinc-containing dust such as zinc ore burnt from zinc concentrate, in addition to electric furnace dust generated during the melting and smelting of scrap in the electric furnace process, which is one of the iron-making processes.

In the electric furnace process, which is one of the steelmaking processes, electric furnace dust is generated as industrial waste containing zinc oxide and accounts for approximately 1.5% to 2.0% of the steel produced during the melting and smelting of scrap. It is said that 8 million tons of electric furnace dust are generated worldwide, and 400,000 tons are generated in Japan.

Most iron scrap comes from abandoned buildings, discarded home appliances, and discarded automobiles. The paint base of abandoned buildings, discarded home appliances, and discarded automobiles is zinc-plated. Scrap also contains paint, plastic, oil, etc. For this reason, electric furnace dust contains heavy metals such as zinc and lead, as well as harmful organic matter such as chlorides and dioxins. However, electric furnace dust also contains about 20-30% iron and 20-30% zinc. Furthermore, crude zinc oxide such as secondary dust contains about 10% iron and about 60% zinc. Therefore, electric furnace dust and the like are extremely useful resources.

Under these circumstances, Patent Document 1 discloses a method for producing zinc, which includes a zinc-containing aqueous solution production process 102 in which an aqueous alkali hydroxide solution is used as an extraction solvent to selectively extract the zinc component in raw materials such as electric furnace dust, an electrolysis process 103 in which electrolysis is carried out using the zinc-containing aqueous solution as the electrolyte to produce zinc, and a chlorine concentration adjustment process 101 prior to the electrolysis process 103 in which the chlorine component contained in raw materials such as electric furnace dust is separated to reduce the chlorine concentration of the zinc-containing aqueous solution.

International Publication No. 2022/118927

However, according to the inventor's investigation, the configuration disclosed in Patent Document 1 employs a configuration for obtaining zinc, which is an electrolysis product that adheres to the surface of the cathode of the electrolysis device used in the electrolysis process 103, but does not disclose or suggest any specific configuration for collecting that zinc.

In particular, according to the inventor's research, in order to mass-produce zinc, which is an electrolytic product, it is necessary to realize an appropriate configuration for determining what characteristics electrolytically generated zinc should be attached to the surface of the cathode, how the attached electrolytically generated zinc should be harvested, and so on.

The present invention was made based on the above considerations, and aims to provide an electrolytic product collection method and an electrolytic product collection system that can attach electrolytically generated zinc to the cathode surface of an electrolytic device while taking into consideration the collection properties, and that can reliably and efficiently collect the attached electrolytically generated zinc.

In order to achieve the above object, the electrolysis product collection method in the first aspect of the present invention includes an aqueous solution preparation step of obtaining a zinc-containing sodium hydroxide aqueous solution by leaching zinc-containing matter derived from zinc-containing dust with an aqueous sodium hydroxide solution, an electrolysis step of performing electrolysis using an electrolysis device including an anode, a cathode made of pure magnesium or a magnesium alloy facing the anode, and an electrolysis cell containing an electrolysis bath using the zinc-containing sodium hydroxide aqueous solution, and a peeling step of peeling off the zinc electrodeposit from the cathode by sequentially contacting a contact member with each of the multiple portions of the zinc electrodeposit obtained as the electrolysis product in the electrolysis step inside the electrolysis cell at predetermined time intervals.

In addition to the first aspect, the present invention provides a second aspect in which the zinc electrodeposit is a powder or dendritic crystal, and the current density applied to the electrolysis at the start of the electrolysis step is greater than the current density applied to the electrolysis after the start of the electrolysis.

In addition to the first or second aspect, the present invention has a third aspect in which the electrodeposition surface on which the zinc electrodeposit is electrodeposited on the cathode is set as a plurality of electrodeposition surfaces that are separated from one another.

In addition to the third aspect, the present invention has a fourth aspect in which, in the peeling step, the contact member is moved while being in contact with a portion of the zinc electroplated on the plurality of electroplating surfaces, and then, after the predetermined time interval, the contact member is moved while being in contact with the remaining portion of the zinc electroplated on the plurality of electroplating surfaces.

In addition to any one of the first to third aspects, the present invention has a fifth aspect in which, in the peeling process, the cathode is vibrated when the contact member is brought into contact with the zinc electrolytic deposit.

In addition to any one of the first to fifth aspects, the present invention has a sixth aspect in which the zinc electrodeposit peeled off from the cathode in the peeling step is crushed after or before being removed from the electrolytic cell.

In addition to any one of the first to sixth aspects, the present invention provides a seventh aspect in which the zinc electrodeposit peeled off from the cathode in the peeling step is washed with water after being removed from the electrolytic cell, and a rust inhibitor is applied to the washed zinc electrodeposit.

In addition to any one of the first to seventh aspects, the present invention provides an eighth aspect in which the zinc electrodeposit peeled off from the cathode in the peeling step is washed with water after being removed from the electrolytic cell, and the washed zinc electrodeposit is compression molded.

In a ninth aspect, the present invention is an electrolysis product collection system comprising: an anode; a cathode made of pure magnesium or a magnesium alloy facing the anode; and an electrolysis cell containing an electrolysis bath using an aqueous zinc-containing sodium hydroxide solution obtained by leaching zinc-containing material derived from zinc-containing dust with an aqueous sodium hydroxide solution; and a peeling mechanism having a contact member that contacts each of a plurality of portions of the zinc electrodeposit obtained as an electrolysis product in the electrolysis process in sequence at predetermined time intervals inside the electrolysis cell to peel off the zinc electrodeposit from the cathode.

According to the first aspect of the present invention, the method for collecting electrolytic products includes an aqueous solution preparation step of obtaining a zinc-containing sodium hydroxide aqueous solution by leaching zinc-containing matter derived from zinc-containing dust with an aqueous sodium hydroxide solution, an electrolysis step of performing electrolysis using an electrolysis device including an anode, a cathode made of pure magnesium or a magnesium alloy facing the anode, and an electrolysis cell containing an electrolysis bath using an aqueous zinc-containing sodium hydroxide solution, and a peeling step of bringing a contact member into contact with each of a plurality of portions of the zinc electrodeposit obtained as an electrolysis product in the electrolysis step in sequence at predetermined time intervals inside the electrolysis cell to peel the zinc electrodeposit from the cathode, so that the electrolytically generated zinc can be loosely attached to the cathode surface of the electrolysis device so as to be easily collected, and the attached electrolytically generated zinc can be reliably and efficiently collected while suppressing unnecessary effects on the electrolysis. Here, in the conventional electrolytic product extraction method in zinc sulfate smelting, since the electrolytic product is densely deposited on the electrode surface in a plate shape, it is necessary to once pull up the electrode plate from the electrolytic cell every day or every other day, mechanically peel off the electrolytic product, and then return the electrode plate to the electrolytic cell again, which is a complicated operation. For this reason, not only is a large crane necessary in terms of equipment, but also the so-called slinging work to the crane on the electrolytic cell and the alignment work of the electrode plates are manual, which requires heavy labor. In addition, although the work of peeling off the electrolytic product has been automated to some extent by equipment, if the peeling ability is poor, there are many cases where the equipment is stopped in an emergency, which may cause delays in operation or, in some cases, the operation may be suspended for several days. On the other hand, in the present invention, which is represented by the first aspect, the cathode is not removed from the electrolytic cell, but is kept in the electrolytic cell, and the electrolytic operation is continued without unnecessarily changing the electrolytic conditions, so that the electrolytic zinc can be peeled off while the electrolytic operation continues. This means that the equipment and manpower required are simplified, electrolysis can be continued in a stable state, and electrolytic zinc can be collected.

Furthermore, according to the electrolysis product recovery method of the second aspect of the present invention, the zinc electrodeposit is made to be a powder or dendrites. Therefore, when the zinc electrodeposit in the form of a powder or dendrites is electrodeposited on the entire electrodeposition surface of the cathode, the zinc electrodeposit generally lacks macroscopic stability and exhibits low-quality electrodeposition properties such as the presence of numerous large nodules. However, by setting the current density used for electrolysis at the start of electrolysis in the electrolysis process to be greater than the current density used for electrolysis after the start of electrolysis, the state of initial electrodeposition nuclei generation is stable, and the adhesion strength of the zinc electrodeposit attached to the electrodeposition surface of the cathode can be stabilized from the start of electrolysis, and the zinc electrodeposit can be electrodeposited as a powder or dendrites that exhibits macroscopic stability and is free of large nodules over the entire electrodeposition surface of the cathode. In other words, it is possible to obtain electrolytically produced zinc of substantially uniform quality across the entire surface of the cathode, and the pure magnesium or magnesium alloy cathode allows the electrolytically produced zinc to adhere loosely to the cathode surface for easy collection, so that electrolytically produced zinc of stable quality can be reliably and efficiently collected.

Furthermore, according to the electrolytic product collection method of the third aspect of the present invention, the electrodeposition surface on which the zinc electrodeposit is electrodeposited on the cathode is set as a plurality of electrodeposition surfaces that are separated from one another, so that the electrolytically generated zinc can be attached to the cathode surface of the electrolytic device in a manner that allows for a high degree of freedom in collection, and the attached electrolytically generated zinc can be collected more reliably and efficiently.

Furthermore, according to the electrolysis product collection method of the fourth aspect of the present invention, in the peeling process, a contact member is moved while being in contact with a portion of the zinc electrodeposits electrodeposited on the multiple electrodeposition surfaces, and then, after a predetermined time interval, the contact member is moved while being in contact with the zinc electrodeposits on the remaining portion of the zinc electrodeposits electrodeposited on the multiple electrodeposition surfaces. This makes it possible to stabilize the current value used for electrolysis so that it does not change unnecessarily, and electrolytically generated zinc of stable quality can be attached to the cathode surface of the electrolysis device.

Furthermore, according to the electrolytic product collection method of the fifth aspect of the present invention, in the peeling process, the cathode is vibrated when the contact member is brought into contact with the zinc electrodeposits, so that the zinc electrodeposits can be peeled off more reliably and efficiently.

Furthermore, according to the electrolytic product collection method of the sixth aspect of the present invention, the zinc electrodeposits peeled off from the cathode in the peeling process are crushed after or before being removed from the electrolytic cell, so that electrolytically produced zinc of the required size can be collected.

Furthermore, according to the seventh aspect of the present invention, the electrolytic product collection method, in which the zinc electrodeposits peeled off from the cathode in the peeling process are washed with water after being removed from the electrolytic cell, and a rust inhibitor is applied to the washed zinc electrodeposits, making it possible to collect electrolytically produced zinc with high rust resistance.

Furthermore, according to the electrolytic product collection method of the eighth aspect of the present invention, the zinc electrodeposits peeled off from the cathode in the peeling step are washed with water after being removed from the electrolytic cell, and the washed zinc electrodeposits are compression molded. Therefore, by taking advantage of the fact that the zinc electrodeposits are metallic, it is possible to obtain a final product of metallic zinc in an easy-to-handle form without the need for molding such as ingot molding.

In addition, according to the ninth aspect of the present invention, the electrolysis product collection system includes an electrolysis device having an anode, a cathode made of pure magnesium or a magnesium alloy facing the anode, and an electrolysis cell containing an electrolysis bath using an aqueous zinc-containing sodium hydroxide solution obtained by leaching zinc-containing material derived from zinc-containing dust with an aqueous sodium hydroxide solution, and a peeling mechanism having a contact member that contacts each of the multiple portions of the zinc electrodeposit obtained as the electrolysis product in the electrolysis process in sequence at predetermined time intervals inside the electrolysis cell to peel the zinc electrodeposit from the cathode. Therefore, the electrolytically generated zinc can be loosely attached to the cathode surface of the electrolysis device so as to be easily collected, and the attached electrolytically generated zinc can be reliably and efficiently collected while suppressing unnecessary effects on the electrolysis.

In addition, the electrolytic product collection system in the ninth aspect of the present invention can be subordinated to a combination of configurations for executing the electrolytic product collection methods in the first to eighth aspects, and the effects they provide are similar to those of the electrolytic product collection methods in the first to seventh aspects.

FIG. 1 is a process diagram of a method for recovering a product by electrolysis according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of an electrolysis product extraction system applied to the electrolysis product extraction method in this embodiment. FIG. 3A is a front view of an anode of an electrolytic product recovery system applied to the electrolytic product recovery method in this embodiment. FIG. 3B is a front view of the cathode of the electrolysis product recovery system applied to the electrolysis product recovery method in this embodiment. FIG. 4A is a front view showing a state in which a peeling mechanism is combined with a cathode of an electrolysis product recovery system applied to the electrolysis product recovery method in this embodiment. FIG. 4B is a top view of FIG. 4A. FIG. 5 is Table 1 showing the amount of impurities in electrolytically produced zinc obtained by the electrolytic product recovery method of this embodiment. FIG. 6 is a diagram showing the configuration of a modified example of an electrolysis product extraction system applied to the electrolysis product extraction method in this embodiment. FIG. 7 is a diagram showing the configuration of another modified example of the electrolysis product collection system applied to the electrolysis product collection method in this embodiment. FIG. 8 is a process diagram of a modified example of the electrolysis product collection method according to this embodiment. FIG. 9A is a front view showing a state in which a peeling mechanism and a hammer device are combined with a cathode of an electrolytic product recovery system applied to the modified electrolytic product recovery method shown in FIG. 8. FIG. 9B is a top view of FIG. 9A. FIG. 10 is a process diagram of another modified example of the electrolytic product collection method according to this embodiment. FIG. 11 is a diagram showing the configuration of an electrolysis product extraction system applied to the electrolysis product extraction method of another modified example shown in FIG. FIG. 12 is a process diagram of a further modified example of the electrolytic product collection method according to the present embodiment. FIG. 13 is a diagram showing the configuration of an electrolysis product extraction system applied to the electrolysis product extraction method of the further modified example shown in FIG.

Below, the electrolytic product collection method and electrolytic product collection system according to an embodiment of the present invention will be described in detail with appropriate reference to the drawings.

1 is a process diagram of the electrolytic product extraction method in this embodiment, and FIG. 2 is a diagram showing the configuration of an electrolytic product extraction system applied to the electrolytic product extraction method in this embodiment. FIG. 3A is a front view of the anode of the electrolytic product extraction system applied to the electrolytic product extraction method in this embodiment, and FIG. 3B is a front view of the cathode of the electrolytic product extraction system applied to the electrolytic product extraction method in this embodiment. FIG. 4A is a front view showing a state in which a peeling mechanism is combined with the cathode of the electrolytic product extraction system applied to the electrolytic product extraction method in this embodiment, and FIG. 4B is a top view of FIG. 4A. FIG. 5 is Table 1 showing the amount of impurities in electrolytically generated zinc by the electrolytic product extraction method in this embodiment. In the figure, the x-axis, y-axis, and z-axis form a three-axis orthogonal coordinate system, with the positive side of the x-axis corresponding to the front, the direction of the z-axis being the vertical direction, and the positive direction of the z-axis corresponding to the upward direction.

As shown in FIG. 1, the electrolytic product collection method sequentially includes an aqueous solution preparation process 101, an electrolysis process 102, a peeling process 103, an extraction process 104, a crushing process 105, and a rust prevention process 106. Note that the extraction process 104, the crushing process 105, and the rust prevention process 106 may be omitted as necessary.

First, in the aqueous solution preparation process 101, zinc-containing dust as raw material 1 and aqueous sodium hydroxide solution 2 are supplied, and the zinc-containing dust is reduced and concentrated to obtain zinc-containing material, which is leached with the aqueous sodium hydroxide solution 2 to obtain an aqueous zinc-containing sodium hydroxide solution 3 containing zinc components. Such zinc-containing dust contains at least zinc compounds such as zinc oxide, and may be primary or secondary dust such as electric furnace dust, blast furnace dust, blast furnace/converter dust, or RHF (Rotary Hearth Furnace) dust, or zinc concentrate ore. In addition, the electrolytic tailings 2' from the electrolysis process 102 may be used as the aqueous sodium hydroxide solution, although it will contain zinc.

In this case, the composition of the zinc-containing sodium hydroxide aqueous solution 3 obtained in the aqueous solution preparation process 101 is preferably such that the concentration of sodium hydroxide is in the range of 150 (g/L) to 560 (g/L) and the concentration of zinc is in the range of 15 (g/L) to 200 (g/L). This is because if the concentration of sodium hydroxide is less than 150 (g/L), the zinc component in the zinc-containing material cannot be dissolved, if the concentration of sodium hydroxide exceeds 560 (g/L), the voltage in the electrolysis process 102 increases and the efficiency of the electrolysis decreases, if the concentration of zinc is less than 15 (g/L), the supply of zinc to the cathode 20 side in the electrolysis process 102, which will be described in detail later, decreases, and the quality of the zinc electrodeposited decreases, and if the concentration of zinc exceeds 200 (g/L), the viscosity of the electrolyte in the electrolysis process 102 increases, leading to a situation in which the voltage in the electrolysis increases. If necessary, the aqueous solution preparation process 101 may include a purification process prior to the leaching process to remove impurities contained in the raw material 1.

Next, in the electrolysis process 102, the zinc-containing sodium hydroxide aqueous solution 3 containing the zinc component obtained in the aqueous solution preparation process 101 is electrolyzed as an electrolyte to obtain the electrolytic product, zinc electrodeposit 4.

Here, in the subsequent steps including the electrolysis step 102, the electrolysis product collection system S1 shown in Figures 2 to 4B can be applied. The electrolysis product collection system S1 includes an anode 10, a cathode 20 located on the positive side of the x-axis relative to the anode 10 and facing the anode 10, an electrolysis cell 30 that houses the anode 10 and the cathode 20, a peeling mechanism 40 provided for the cathode 20, a power source 50 that applies current to the anode 10 and the cathode 20, a screw conveyor 60 that extends obliquely upward from the bottom side of the electrolysis cell 30, a crusher 70 provided on the upper end side of the screw conveyor 60, and a rust inhibitor applicator 80 provided below the crusher 70. The anode 10, the cathode 20, the electrolysis cell 30, and the power source 50 constitute an electrolysis device E. Although only one anode 10 and one cathode 20 are shown, multiple anodes 10 and cathodes 20 may be provided facing each other as necessary. In addition, if the extraction process 104, the crushing process 105, and the rust prevention process 106 can be omitted, the screw conveyor 60, the crusher 70, and the rust prevention agent applicator 80 can be omitted.

As shown in Figures 2 and 3A, the anode 10 has an electrode 12 and a cross member 14, both of which are conductive. As an example, the electrode 12 is a rectangular flat plate parallel to the y-z plane, and is connected to the cross member 14 and supported so as to hang down from it. From the standpoint of electrolysis stability, the electrode 12 is preferably made of pure nickel or a so-called DSE (Dimensionally Stable Electrode: platinum group coated titanium electrode). The cross member 14 is connected to the positive side of the power source 50 via a bus bar (typically made of copper) 52 or the like.

As shown in Figures 2 and 3B to 4B, the cathode 20 has an electrode 22 and a cross member 24, all of which are conductive, and an electrically insulating masking member 26. As an example, the electrode 22 is a rectangular flat plate parallel to the y-z plane and facing the electrode 12 of the anode 10, and is connected to the cross member 24 and supported so as to hang down from the cross member 24. The electrode 22 is typically made of pure magnesium or a magnesium alloy. The cross member 24 is connected to the negative side of the power source 50 via a bus bar (typically made of copper) 54 or the like. In more detail, it is preferable that the electrode 22 is sandwiched between a pair of cross members 24, 24 facing each other in the x-axis direction to securely fix the electrode 22. Note that, for the cross member 14 supporting the anode 10, a configuration in which the electrode 12 is sandwiched and fixed between a pair of cross members 14, 14, similar to the pair of cross members 24, 24, can also be adopted. The masking member 26 is fixed to the electrode 22 by adhesion or the like, and has a comb-like shape as seen in the x-axis direction, for example. The masking member 26 has an upper flat portion that is a comb-like base 26a on the flat surface located at the upper part (side of the horizontal member 24) of the electrode 22, and has a plurality of teeth 26b that are extending portions that branch into a plurality and extend downward on the flat surface located below the upper part (side of the horizontal member 24) of the electrode 22. The flat surface of the electrode 22 is exposed between the plurality of teeth 26b of the masking member 26, and the flat surface of the electrode 22 exposed while being divided by the plurality of teeth 26b of the masking member 26 in this way becomes the electrodeposition surface 28. The shape of the masking member 26 is not limited to a comb-like shape in principle, as long as it can divide the flat surface of the electrode 22 and define a plurality of exposed portions on the flat surface of the electrode 22. For example, instead of providing multiple teeth 26b in the masking member 26, the base 26a can be extended to the flat surface located below the upper part of the electrode 22 (side of the cross member 24), and a porous shape can be adopted in which multiple through holes are provided in the extended base. Note that the figure shows an example in which the masking member 26 is provided on both sides of the electrode 22, taking into consideration that multiple anodes 10 are provided. Also, it is possible to provide a dividing member other than the masking member 26, as long as it can divide the flat surface of the electrode 22 and define multiple exposed portions on the flat surface of the electrode 22.

As shown in FIG. 2, the electrolytic cell 30 is a container that contains the anode 10, the cathode 20, and the electrolytic bath 32, whose electrolyte is the zinc-containing sodium hydroxide aqueous solution 3 containing the zinc component obtained in the aqueous solution preparation process 101, and is electrically insulating. In addition, at the bottom of the electrolytic cell 30, a storage section 34 is provided in which the zinc electrodeposits 4 peeled off from each electrodeposition surface 28 of the cathode 20 fall into the electrolytic bath 32 as zinc flakes 5, and the zinc flakes 5 are stored separately from the electrolytic bath 32 or together with the electrolytic bath 32. The storage section 34 is electrically insulating and has a truncated cone shape in which the cross section cut in the x-y plane becomes smaller as it goes downward from the electrolytic cell 30, so that the zinc flakes 5 that have fallen into the electrolytic bath 32 are collected at the bottom of the storage section 34, as if being guided to the contour of the truncated cone shape. In addition, a portion of the zinc-containing sodium hydroxide aqueous solution 3, which is the electrolyte of the electrolytic bath 32, is sent to the circulation tank 90, where it is temporarily stored, and then circulated by being sent to the electrolytic tank 30 using the generated pressure of the pump 92.

In other words, in the electrolysis process 102, a current is passed between the electrode 12 of the anode 10 and the electrode 22 of the cathode 20 using the power source 50 as a power source, and the zinc-containing sodium hydroxide aqueous solution 3 containing the zinc component obtained in the aqueous solution preparation process 101 is electrolyzed as an electrolyte, and the electrolytic product, zinc electrodeposits 4, are precipitated (electrodeposited) on each electrodeposition surface 28 of the electrode 22 of the cathode 20, and the electrolytic product, zinc electrodeposits 4, are adhered to and protrude from the portions of the masking member 26 adjacent to each electrodeposition surface 28, covering them.

In this case, other than the composition of the zinc-containing sodium hydroxide aqueous solution 3 that becomes the electrolytic bath 32, the electrolytic current density is preferably within the range of 400 (A) to 2500 (A) per unit square meter, and the liquid temperature of the electrolytic bath 32 is preferably within the range of 30 (°C) to 75 (°C). This is because if the electrolytic current density is less than 400 (A) per unit square meter, the productivity of the zinc electrodeposit 4, which is the electrolytic product, will decrease, if the electrolytic current density exceeds 2500 (A) per unit square meter, the electrolytic voltage will increase and the power cost will rise, if the liquid temperature of the electrolytic bath 32 is less than 30 (°C), the electrolytic voltage will also increase, and if the liquid temperature of the electrolytic bath 32 exceeds 80 (°C), the cost of the materials for manufacturing the electrolytic cell 30 will rise and the quality of the zinc electrodeposit 4, which is the electrolytic product, will decrease.

In other words, by performing electrolysis using the electrolysis product collection system S1 including the cathode 20 whose electrode 22 is made of pure magnesium or a magnesium alloy, while satisfying the composition conditions of the zinc-containing sodium hydroxide aqueous solution 3 obtained in the aqueous solution preparation step 101 and the electrolysis conditions, the zinc electrodeposit 4, which is the electrolysis product, adheres loosely to the electrodeposition surface 28 of each electrode 22 of the cathode 20 in the form of powder or dendrites with a small contact area, and as a result, its adhesion is relatively weak. This is thought to be due to the fact that, while the electrolysis conditions as described above are the same, if the electrode 22 of the cathode 20 is made of something other than pure magnesium or a magnesium alloy, zinc electrodeposits that adhere in a film-like manner and have a relatively strong adhesion are obtained on the electrodeposition surface 28 of each electrode 22 of the cathode 20.

In addition, since the flat surface of the electrode 22 of the cathode 20 is partially covered by the masking member 26, the current density of the electrolysis at the electrode 22 increases compared to when the masking member 26 is not provided, and immediately after the start of electrolysis, zinc electrodeposits 4, which are the product of electrolysis, are rapidly deposited on each electrodeposition surface 28 of the electrode 22 of the cathode 20 divided by the masking member 26. If electrolysis is further continued, the zinc electrodeposits 4 that deposit and continue to grow on the electrodeposition surface 28 of the electrode 22 of the cathode 20 will protrude from each of the divided electrodeposition surfaces 28 to the periphery and will cover and adhere to the teeth 26b, etc. of the masking member 26. Therefore, compared to the current density of electrolysis at the beginning of electrolysis when the zinc electrodeposits 4 are deposited only on each electrodeposition surface 28, the current density of electrolysis from the middle of electrolysis onwards when the zinc electrodeposits 4 are deposited and adhere to each tooth 26b, etc. of the masking member 26 will decrease. Here, from the viewpoint of depositing and adhering the zinc electrodeposit 4 quickly at first and then stably to each electrodeposition surface 28 of the electrode 22 of the cathode 20 and each tooth portion 26b of the masking member 26, it is preferable to increase the current density of the electrolysis in the early stage of the electrolysis by 30% or more compared to the current density of the subsequent electrolysis. This results in a zinc electrodeposit 4 with stable properties and excellent adhesion.

Next, in the peeling process 103, the zinc electrodeposit 4, which is the electrolytic product obtained in the electrolysis process 102, is peeled off from the cathode 20 to obtain peeled zinc peeling material 5. The peeling process 103 is performed not only when the electrolysis process 102 is completed, but also during the period in which the electrolysis process 102 is being performed.

Here, as shown in Figures 2, 4A and 4B, the peeling mechanism 40 is disposed in the electrolytic cell 30 so as to face the cathode 20, and has a contact member 44 supported by a pair of frame members 42, 42 that extend in the z-axis direction and face each other in the y-axis direction. The pair of frame members 42, 42 are electrically insulating, and are attached to the attachment target part, such as the electrolytic cell 30, by fixing members not shown so as to be freely movable in the z-axis direction. The contact member 44 is an electrically insulating rod-shaped member that has both ends fixed to the pair of frame members 42, 42 and extends in the y-axis direction. In detail, although only one contact member 44 is shown for convenience, multiple contact members 44 are typically arranged at equal intervals in the direction of the z-axis, and by moving the pair of frame members 42, 42 in the direction of the z-axis, the contact member 44 can be freely moved to cover the entirety of the multiple divided electroplating surfaces 28 of the electrode 22 of the cathode 20 and the multiple tooth portions 26b of the masking member 26, and as it moves, the contact member 44 comes into contact with and peels off the zinc electroplating material 4 that has precipitated and loosely adhered to the electroplating surface 28, and the zinc electroplating material 4 that has protruded and loosely adhered to the tooth portions 26b, etc., to obtain peeled zinc flakes 5. Since the peeled zinc flakes 5 thus peeled off fall vertically downward in the electrolytic bath 32, which is the direction of gravity, the movement direction of the contact member 44 relative to the electrode 22 is preferably the vertical direction (up and down direction) indicated by the double arrow in the figure, and accordingly, when the masking member 26 has a comb-shaped shape, the extension direction of the multiple teeth 26b is preferably the direction of the z-axis, that is, the vertical direction (up and down direction). Note that the contact member 44 during movement can peel off the zinc electrodeposits 4 deposited and loosely attached on the electrodeposition surface 28 and the zinc electrodeposits 4 protruding and loosely attached to the teeth 26b, etc., by lightly contacting them, thereby preventing the contact member 44 from contacting the electrode 22 or the masking member 26 unnecessarily strongly and causing damage to them. In addition, in the figure, an example is shown in which the peeling mechanism 40 is provided on both sides of the cathode 20, taking into consideration that multiple anodes 10 are provided, but it is sufficient to provide the peeling mechanism 40 on the side of the cathode 20 facing the anode 10. In addition, in the figure, an example is shown in which one peeling mechanism 40 is provided on one side of the cathode 20, that is, two peeling mechanisms 40 in total on both sides, but the peeling mechanism 40 may be provided only one in total or three or more in total, taking into consideration the size of the electrode 22 of the cathode 20 and the degree of freedom of the peeling operation. In addition, the contact member 44 may be movably attached to the pair of frame members 42, 42. In addition, two pair of frame members 42, 42 are provided for one peeling mechanism 40, but only one or three or more may be provided as necessary.

In other words, in the peeling process 103, the contact member 44 of the peeling mechanism 40 is moved to contact the zinc electrodeposits 4 deposited (electrodeposited) on each electrodeposited surface 28 of the electrode 22 of the cathode 20 in the electrolysis process 102, and the zinc electrodeposits 4 that are protruding and attached to the portions of the masking member 26 adjacent to each electrodeposited surface 28, and the zinc electrodeposits 4 are peeled off from the electrodeposited surface 28 and the masking member 26, obtaining peeled zinc peelings 5. The zinc peelings 5 move down through the electrolytic bath 32 toward the reservoir 34 under their own weight.

In this case, in the peeling process 103, it is preferable to move the contact member 44 to contact only a part of the zinc electrodeposit 4 in the middle of electrolysis while moving it, and to peel off only a part of the zinc electrodeposit 4 in the middle of electrolysis, rather than peeling off the entire zinc electrodeposit 4 in the middle of electrolysis by moving the contact member 44 and contacting it all at once while the zinc electrodeposit 4 in the middle of electrolysis is being deposited (electrodeposited) on each electrodeposited surface 28 of the electrode 22 of the cathode 20 and the entire zinc electrodeposit 4 in the middle of electrolysis while sticking to the part of the masking member 26 adjacent to each electrodeposited surface 28. This is because, if the entire zinc electrodeposit 4 in the middle of electrolysis is peeled off all at once, the current density during electrolysis will change unnecessarily, making the state of electrolysis being performed unstable, and this is to prevent such a situation from occurring. In addition, since the state where the zinc electrodeposit 4 is entirely electrodeposited so as to cover not only the electrodeposited surface 28 but also the masking member 26 is the state where the electrolysis voltage is the lowest, it is preferable to sequentially peel off only a part of the zinc electrodeposit 4 while maintaining the state where the zinc electrodeposit 4 is electrodeposited so as to cover not only the electrodeposited surface 28 but also the masking member 26. In this way, the timing for peeling off only a part of the zinc electrodeposit 4 during electrolysis may be set corresponding to the time when a predetermined amount of the zinc electrodeposit 4 adheres after the start of electrolysis in the electrolysis step 102, and typically, may be set corresponding to the time when the zinc electrodeposit 4 protrudes not only onto the electrodeposited surface 28 but also onto the part of the masking member 26 adjacent to the electrodeposited surface 28 from the time when electrolysis in the electrolysis step 102 is started, and adheres so as to cover not only the electrodeposited surface 28 but also the masking member 26. In addition, in this case, the timing of peeling off the zinc electrodeposit 4 is preferably set to correspond to the time when the same amount of zinc electrodeposit 4 adheres to each electrodeposition surface 28, etc., from which only a part of the zinc electrodeposit 4 is peeled off, since the electrical resistance increases and the voltage of electrolysis increases in the part where the zinc electrodeposit 4 is no longer present at the time of peeling off. However, if the zinc electrodeposit 4 is electrodeposited for more than two hours, for example, the growing zinc electrodeposit 4 may reach the opposing anode 10 and connect with it, causing a short circuit between the anode 10 and the cathode 20. If a short circuit occurs, electrolysis is not performed and a large amount of power is wasted, and the quality of the zinc electrodeposit 4 is also adversely affected. Next, after peeling off only a part of the zinc electrodeposit 4 during electrolysis, the timing of peeling off the remaining zinc electrodeposit 4 during electrolysis other than the part may be typically set to correspond to the time when the same amount of zinc electrodeposit 4 adheres to each electrodeposition surface 28, etc., from which only a part of the zinc electrodeposit 4 is peeled off. Thereafter, the zinc electrodeposit 4 may be partially peeled off at the same set timing. For example, although it depends on the electrolysis conditions, the time interval between peeling off only a part of the zinc electrodeposit 4 during electrolysis and peeling off the remaining zinc electrodeposit 4 during electrolysis is about 10 minutes to 2 hours, and at each such predetermined time interval, the contact member 44 is moved and brought into contact with the zinc electrodeposit 4 in the corresponding area until the electrolysis process 102 is completed, and the zinc electrodeposit 4 is peeled off. In addition, the reason why the entire zinc electrodeposit 4 is not peeled off at once is to suppress a sudden increase in the electrolysis voltage, which would occur if the entire zinc electrodeposit 4 were peeled off at once. In addition, if the attached zinc electrodeposit 4 remains at the time the electrolysis process 102 is completed, the contact member 44 is moved and brought into contact with the remaining zinc electrodeposit 4, and this is also peeled off.

Next, in the extraction process 104, the zinc flakes 5 that have descended through the electrolytic bath 32 and reached the storage section 34 are extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30. The zinc flakes 5 thus extracted from the storage section 34 are sent to the crusher 70 via the screw conveyor 60. If the extraction process 104 is omitted, the zinc flakes 5 may be pumped out of the electrolytic cell 30.

Here, the screw conveyor 60 has a screw member 62 that transports the zinc flakes 5 diagonally upward, an inlet container 64 for supplying the zinc flakes 5 from the storage section 34 to the screw member 62, and an outlet container 66 for conveying the transported zinc flakes 6 transported by the screw member 62 toward the crusher 70. By transporting the zinc flakes 5 diagonally upward in this manner using the screw conveyor 60, it becomes possible to juxtapose the crusher 70 in the horizontal direction indicated by the x-axis direction relative to the electrolytic cell 30, making it possible to prevent unnecessary expansion of the vertical size of the electrolytic product collection system S1. The zinc flakes 5 extracted from the electrolytic cell 30 in the extraction process 104 may be used as the final product as is.

Next, in the crushing process 105, the zinc flakes 6 that were extracted from the electrolytic cell 30 in the extraction process 104 and sent to the crusher 70 via the screw conveyor 60 are crushed to a predetermined size. The zinc flakes 7 thus crushed by the crusher 70 are sent to the rust inhibitor applicator 80. Here, the crusher 70 has a crushing member 72 that crushes the zinc flakes 6 sent to the crusher 70 to a predetermined size. The zinc flakes 7 crushed by the crusher 70 in the crushing process 105 may be used as the final product as is. In addition, if the zinc-containing sodium hydroxide aqueous solution used as the electrolytic bath 32 is attached to the zinc flakes 6 sent to the crusher 70, they may be sent to the circulation tank 90 for temporary storage and then returned to the electrolytic cell 30 using the generated pressure of the pump 92.

Finally, in the rust prevention process 106, the zinc peeling material 7 that has been crushed by the crusher 70 in the crushing process 105 and sent to the rust inhibitor applicator 80 is coated with rust inhibitor 9 to obtain zinc peeling material (metallic zinc) 8 coated with rust inhibitor 9 as the final product. Here, the rust inhibitor applicator 80 has a centrifuge 82, and after the zinc peeling material 7 sent to the rust inhibitor applicator 80 is washed in the centrifuge 82, the washed zinc peeling material 7 is coated with rust inhibitor 9. Examples of the rust inhibitor 9 include BTA (benzotriazole).

Below, experimental example 1 of this embodiment will be explained.

(Experimental Example 1)
In this experimental example, in the aqueous solution preparation step (a combination of the leaching step and the solution purification step) 101, the electric furnace dust as the raw material 1 is leached with the electrolytic tail solution 2' (sodium hydroxide concentration 450 (g/L), zinc concentration 40 (g/L) to 50 (g/L) inclusive) to obtain an aqueous zinc-containing sodium hydroxide solution (sodium hydroxide concentration 450 (g/L), zinc concentration 130 (g/L) inclusive), which is added to the electrolytic solution (sodium hydroxide concentration 450 (g/L), zinc concentration 40 (g/L) to 50 (g/L) inclusive) circulating between the electrolytic cell 30 and the circulation cell 90. The amount of the aqueous solution added is set to a level that replenishes the zinc concentration that is reduced by electrodeposition. In the electrolysis process 102, the electrolysis conditions were an electrolysis current density of 1200 (A) per square meter and a liquid temperature of the electrolytic bath 32 of 60 (°C), in which the electrode 12 of the anode 10 was made of pure nickel, and the electrode 22 of the cathode 20 was made of pure magnesium, and a masking member 26 was applied. Next, in the peeling process 103, 30 minutes after the start of electrolysis, the contact member 44 of the peeling mechanism 40 was moved and brought into contact with 1/2 of the zinc electrodeposits 4 deposited on each electrodeposition surface 28 of the electrode 22 of the cathode 20 and the zinc electrodeposits 4 attached to the portions of the masking member 26 adjacent to each electrodeposition surface 28, and the corresponding 1/2 of the zinc electrodeposits 4 was peeled off, and 15 minutes after that point, the contact member 44 of the peeling mechanism 40 was moved and brought into contact with the remaining 1/2 of the zinc electrodeposits 4, and the corresponding remaining 1/2 of the zinc electrodeposits 4 was peeled off. Here, the electrolysis voltage when 1/2 of the zinc electrodeposits 4 was peeled off 30 minutes after the start of electrolysis was 0.28 (V), and the electrolysis voltage when the remaining 1/2 of the zinc electrodeposits 4 was peeled off 15 minutes after that point was 0.29 (V). Furthermore, such a peeling operation was repeated during the execution of the electrolysis step 102, and the zinc electrodeposits 4 remaining even at the completion of the electrolysis step 102 were peeled off. Next, in the extraction step 104, the zinc peeled material 5 peeled off by the contact member 44 of the peeling mechanism 40, descended in the electrolytic bath 32, and reached the storage section 34 was extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30 and sent to the crusher 70 via the screw conveyor 60, and in the crushing step 105, the zinc peeled material 6 sent to the crusher 70 was crushed. Then, in the rust prevention step 106, the zinc peeled material 7 crushed by the crusher 70 was filtered in the centrifuge 82 of the rust inhibitor applicator 80, and then washed with water three times. After confirming that the pH of the washing water was about 10 to 11, a rust inhibitor solution having a BTA concentration of 5 (g/L) was applied to the filter cloth as the rust inhibitor 9. After the application of the rust-preventive liquid, metallic zinc 8 was collected with a scraper from inside the centrifuge 82. The metallic zinc 8 collected in this manner corresponds to the purest zinc as specified by JIS, and as shown in Table 1 in Fig. 5, this experimental example was repeated three times to obtain samples 1 to 3 of metallic zinc 8, and the amounts of components other than zinc were stably suppressed to minute amounts.

Now, since various modifications of the electrolytic product collection system that can be applied to the electrolytic product collection method of this embodiment are possible, a detailed description will be given below with reference to Figures 6 and 7.

(System Variations)
FIG. 6 is a diagram showing the configuration of a modified example of an electrolysis product extraction system applied to the electrolysis product extraction method in this embodiment.

As shown in FIG. 6, the electrolytic product extraction system S2 in this modified example differs from the electrolytic product extraction system S1 described above mainly in that the screw conveyor 60 is replaced with a packet conveyor 110. The packet conveyor 110 has a packet member 112 that contains the zinc flakes 5, a belt 114 that carries the packet member 112, and a roller 116 that drives the belt 114. In other words, in the extraction process 104 using the electrolytic product extraction system S2, the zinc flakes 5 that have descended through the electrolytic bath 32 and reached the storage section 34 are extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30, and the zinc flakes 5 thus extracted from the storage section 34 are transported to the crusher 70 by moving the packet member 112 that contains the zinc flakes 5.

Below, we explain experimental example 2 of this modified example.

(Experimental Example 2)
In this experimental example, in the aqueous solution preparation step (a combination of the leaching step and the solution purification step) 101, the electric furnace dust as the raw material 1 is leached with the electrolytic tail solution 2' (sodium hydroxide concentration 450 (g/L), zinc concentration 40 (g/L) to 50 (g/L) inclusive) to obtain an aqueous zinc-containing sodium hydroxide solution (sodium hydroxide concentration 450 (g/L), zinc concentration 130 (g/L) inclusive), which is added to the electrolytic solution (sodium hydroxide concentration 450 (g/L), zinc concentration 40 (g/L) to 50 (g/L) inclusive) circulating between the electrolytic cell 30 and the circulation cell 90. The amount of the aqueous solution added is set to a level that replenishes the zinc concentration that is reduced by electrodeposition. In the electrolysis process 102, the electrolysis conditions were an electrolysis current density of 1000 (A) per square meter and a liquid temperature of the electrolytic bath 32 of 60 (°C), in which the electrode 12 of the anode 10 was made of pure nickel, and the electrode 22 of the cathode 20 was made of pure magnesium, and a masking member 26 was applied. Next, in the peeling process 103, at the time 45 minutes after the start of electrolysis, the contact member 44 of the peeling mechanism 40 was moved and brought into contact with 1/2 of the zinc electrodeposits 4 deposited on each electrodeposition surface 28 of the electrode 22 of the cathode 20 and the zinc electrodeposits 4 attached to the portions of the masking member 26 adjacent to each electrodeposition surface 28, and the corresponding 1/2 of the zinc electrodeposits 4 was peeled off, and at the time 15 minutes after that point, the contact member 44 of the peeling mechanism 40 was moved and brought into contact with the remaining 1/2 of the zinc electrodeposits 4, and the corresponding remaining 1/2 of the zinc electrodeposits 4 was peeled off. Here, the electrolysis voltage when 1/2 of the zinc electrodeposits 4 was peeled off 30 minutes after the start of electrolysis was 0.25 (V), and the electrolysis voltage when 15 minutes after that point was peeled off was 0.26 (V). Furthermore, such a peeling operation was repeated during the execution of the electrolysis step 102, and the zinc electrodeposits 4 remaining even at the completion of the electrolysis step 102 were peeled off. Next, in the extraction step 104, the zinc peelings 5 peeled off by the contact member 44 of the peeling mechanism 40, descended in the electrolytic bath 32, and reached the storage section 34 were extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30, and sent to the crusher 70 via the packet conveyor 110, and in the crushing step 105, the zinc peelings 6 sent to the crusher 70 were crushed. Then, in the rust prevention step 106, the zinc peelings 7 crushed by the crusher 70 were filtered in the centrifuge 82 of the rust inhibitor applicator 80, and then washed with water three times. After confirming that the pH of the washing water was about 10 to 11, a rust inhibitor solution having a BTA concentration of 5 (g/L) was applied to the filter cloth as the rust inhibitor 9. After the application of the rust-preventive liquid, metallic zinc 8 was collected with a scraper from inside the centrifuge 82. The metallic zinc 8 collected in this manner corresponds to the purest zinc specified by JIS, and, as in Experimental Example 1, components other than zinc were stably suppressed to minute amounts.

(Another variation of the system)
FIG. 7 is a diagram showing the configuration of another modified example of the electrolysis product collection system applied to the electrolysis product collection method in this embodiment.

As shown in FIG. 7, the electrolytic product extraction system S3 in this modification differs from the electrolytic product extraction system S1 described above in that the transport of zinc flakes 5 by the screw conveyor 60 is replaced by transport of zinc flakes 5 using the generated pressure of the pump 120. In other words, in the extraction process 104 using the electrolytic product extraction system S3, the zinc flakes 5 that have descended through the electrolytic bath 32 and reached the storage section 34 are extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30 through the valve 122, and the zinc flakes 5 thus extracted from the storage section 34 are transported to the crusher 70 by moving them using the generated pressure of the pump 120. In this modification, a receiving vessel 124 is provided between the valve 122 and the crusher 70, and if the zinc flakes 6 sent to the receiving vessel 124 have the zinc-containing sodium hydroxide aqueous solution used as the electrolytic bath 32 attached thereto, they may be sent to the circulation vessel 90 for temporary storage, and then returned to the electrolytic cell 30 using the static pressure of the pump 92.

The electrolytic product collection method of this embodiment includes an aqueous solution preparation step 101 in which zinc-containing substances derived from zinc-containing dust 1 are leached with an aqueous sodium hydroxide solution 2 to obtain an aqueous zinc-containing sodium hydroxide solution 3; an electrolysis step 102 in which electrolysis is performed using an electrolysis device E equipped with an anode 10, a cathode 20 made of pure magnesium or a magnesium alloy facing the anode 10, and an electrolysis cell 30 containing an electrolysis bath 32 using the aqueous zinc-containing sodium hydroxide solution 3; and a peeling step 103 in which the contact member 44 is brought into contact with each of the multiple portions of the zinc electrodeposit 4 obtained as an electrolysis product in the electrolysis step 102 in the electrolysis cell 30 at predetermined time intervals to peel the zinc electrodeposit 4 from the cathode 20. Therefore, the electrolytically generated zinc 4 is loosely attached to the cathode surface 28 of the electrolysis device E so as to be easily collected, and the attached electrolytically generated zinc 4 can be reliably and efficiently collected while suppressing unnecessary effects on the electrolysis.

Furthermore, in the electrolysis product recovery method of this embodiment, the zinc electrodeposit 4 is made to be a powder or dendritic crystals, and when the zinc electrodeposit 4 in the form of a powder or dendritic crystals is electrodeposited over the entire electrodeposition surface 28 of the cathode 20, the zinc electrodeposit 4 generally lacks macroscopic stability and exhibits low-quality electrodeposition properties such as the presence of numerous large nodules. However, by setting the current density used for electrolysis at the start of electrolysis in the electrolysis process 102 to be greater than the current density used for electrolysis after the start of electrolysis, the state of initial electrodeposition nuclei generation is stabilized, and the adhesion strength of the zinc electrodeposit 4 attached to the electrodeposition surface 28 of the cathode 20 can be stabilized from the start of electrolysis, and the zinc electrodeposit 4 can be electrodeposited as a powder or dendritic crystals exhibiting macroscopic stability and free of large nodules over the entire electrodeposition surface 28 of the cathode 20. In other words, it is possible to obtain electrolytically produced zinc 4 of substantially uniform quality across the entire surface of the cathode 20, and the electrolytically produced zinc 4 can be loosely attached to the cathode surface 20 by the action of the pure magnesium or magnesium alloy cathode, making it easy to collect, so that electrolytically produced zinc 4 of stable quality can be reliably and efficiently collected.

Furthermore, in the electrolytic product collection method of this embodiment, the electrodeposition surface 28 on which the zinc electrodeposit 4 is electrodeposited on the cathode 20 is set as a plurality of electrodeposition surfaces 28 that are separated from one another, so that the electrolytically generated zinc 4 can be attached to the cathode surface 20 of the electrolytic device E in a manner that allows for a high degree of freedom in collection, and the attached electrolytically generated zinc 4 can be collected more reliably and efficiently.

In addition, in the electrolytic product collection method of this embodiment, in the peeling process 103, the contact member 44 is moved while being in contact with a portion of the zinc electrodeposits 4 electrodeposited on the multiple electrodeposition surfaces 28, and then, after a predetermined time interval, the contact member 44 is moved while being in contact with the zinc electrodeposits 4 on the remaining portion of the zinc electrodeposits 4 electrodeposited on the multiple electrodeposition surfaces 28. This makes it possible to stabilize the current value used for electrolysis so that it does not change unnecessarily, and electrolytically generated zinc 4 of stable quality can be attached to the cathode surface 28 of the electrolysis device E.

In addition, in the electrolytic product collection method of this embodiment, the zinc electrodeposit 5 peeled off from the cathode 20 in the peeling process 103 is crushed after being removed from the electrolytic cell 30, so that electrolytically produced zinc 7 of the required size can be collected.

In addition, in the electrolytic product collection method of this embodiment, the zinc electrodeposit 5 peeled off from the cathode 20 in the peeling process 103 is washed with water after being removed from the electrolytic cell 30, and the washed zinc electrodeposit is coated with a rust inhibitor 9, so that electrolytically produced zinc 8 with high rust resistance can be collected.

In addition, the electrolysis product collection system of this embodiment includes an electrolysis device E including an anode 10, a cathode 20 made of pure magnesium or a magnesium alloy facing the anode 10, and an electrolysis cell 30 containing an electrolysis bath 32 using a zinc-containing sodium hydroxide aqueous solution 3 obtained by leaching zinc-containing material derived from zinc-containing dust 1 with a sodium hydroxide aqueous solution 2, and a peeling mechanism 40 having a contact member 44 that contacts each of the multiple parts of the zinc electrodeposit 4 obtained as an electrolysis product in the electrolysis device E in sequence at predetermined time intervals and peels the zinc electrodeposit 4 from the cathode 20. Therefore, the electrolytically generated zinc 4 is loosely attached to the cathode surface 28 of the electrolysis device E so as to be easily collected, and the attached electrolytically generated zinc 4 can be reliably and efficiently collected while suppressing unnecessary effects on the electrolysis.

Now, since various modifications of the electrolytic product collection method of this embodiment are possible, we will further explain it in detail below with reference to Figures 8 to 13.

(Modification of the method)
Figure 8 is a process diagram of a modified electrolytic product extraction method in this embodiment, Figure 9A is a front view showing a peeling mechanism and a hammer device combined with the cathode of an electrolytic product extraction system applied to the modified electrolytic product extraction method shown in Figure 8, and Figure 9B is a top view of Figure 9A.

As shown in FIG. 8, the main difference between the electrolytic product collection method in this modified example and the electrolytic product collection method in the present embodiment described above is that the peeling process 103 is replaced with a vibration peeling process 103'.

Specifically, in the vibration peeling process 103', the contact member 44 of the peeling mechanism 40 is moved to contact the zinc electrolytic deposits 4 deposited (electrodeposited) on each electrodeposited surface 28 of the electrode 22 of the cathode 20 in the electrolysis process 102, and the zinc electrolytic deposits 4 protruding and attached to the portions of the masking member 26 adjacent to each electrodeposited surface 28, and when peeling the zinc electrolytic deposits 4 from the electrodeposited surface 28 and the masking member 26, the cathode 20 is vibrated to enhance the function of the peeling mechanism 40 that peels the zinc electrolytic deposits 4, and the amount of zinc electrolytic deposits 4 peeled off per unit time is increased, and peeled zinc peelings 5 are obtained.

9A and 9B, typically, in the electrolytic product extraction system S1' applied to the electrolytic product extraction method of this modified example, two hammer devices 46 are provided on one side of the cathode 20 (the side on the negative x-axis side in the figure) between a pair of frame members 42, 42, facing the cross member 24 in the x-axis direction. The hammer device 46 is an impact vibration device that is attached to a support member (not shown) and has an impact member (not shown) that applies an impact force to the cross member 24 in a relatively short predetermined time period in the x-axis direction (the positive x-axis direction in the figure). In other words, the hammer device 46 has the function of vibrating the cathode 20 in the x-axis direction perpendicular to the electrodeposition surface 28 and the masking member 26. Here, from the viewpoint of reinforcing the function of the peeling mechanism 40 to peel off the zinc electrodeposit 4 and increasing the amount of zinc electrodeposit 4 peeled off, it is preferable that the hammer device 46 strikes the cross member 24 at the same time or before the timing when the movement of the contact member 44 starts, and the strike is ended at the same time or after the timing when the movement of the contact member 44 ends. In addition, the direction in which the hammer device 46 strikes the cross member 24 may be a direction intersecting the x-axis direction, as long as it can generate a vibration component that vibrates the electrodeposition surface 28 and the masking member 26 in the x-axis direction perpendicular to the surface. In addition, the hammer device 46 may be provided on one side of the cathode 20 only one, or three or more, as necessary, or may be provided on both sides of the cathode 20.

In the electrolytic product collection method of this modified example, in the vibration peeling process 103', the cathode 20 is vibrated when the contact member 44 is brought into contact with the zinc electrodeposit 4, so that the zinc electrodeposit 4 can be peeled off more reliably and efficiently.

Another variation of the method
FIG. 10 is a process diagram of another modified electrolysis product extraction method in this embodiment, and FIG. 11 is a diagram showing the configuration of an electrolysis product extraction system applied to the another modified electrolysis product extraction method shown in FIG.

As shown in FIG. 10, the main difference between the electrolytic product collection method in this modified example and the electrolytic product collection method in the present embodiment described above is that a molding process 107 is added after the rust prevention process 106.

Specifically, in the molding process 107, the zinc flakes 7 sent to the rust inhibitor applicator 80 in the rust prevention process 106 are compression molded into zinc flakes 8 to which the rust inhibitor 9 has been applied, to obtain molded zinc flakes 8' (metallic zinc) as the final product. Note that the zinc flakes to be compression molded may be the zinc flakes 7 sent to the rust inhibitor applicator 80 that have only been washed with water.

More specifically, as shown in FIG. 11, in an electrolytic product extraction system S1'' typically applied to the electrolytic product extraction method of this modified example, a press molding device 130 is provided downstream of the rust inhibitor applicator 80. The press molding device 130 has an upper mold and a lower mold, both of which have their reference numbers omitted. In the press molding device 130, the zinc flakes 8 sent to the rust inhibitor applicator 80 in the rust prevention process 106 are placed between the upper mold and the lower mold, and then the zinc flakes 8 are compressed by applying pressure while closing the upper mold toward the lower mold, thereby obtaining a compressed molded zinc (metallic zinc) 8', which is a press molded product that reflects the predetermined mold shape defined between the upper mold and the lower mold.

In the electrolytic product extraction method of this modified example described above, the zinc electrodeposit peeled off from the cathode 20 in the peeling process 103 is washed with water after being removed from the electrolytic cell 30, and the washed zinc electrodeposit 8 is compression molded. Therefore, by taking advantage of the fact that the zinc electrodeposit 8 is a metal, it is possible to easily obtain a final product of metallic zinc in an easy-to-handle form without the need for casting-like molding such as ingot molding.

(Another variation of the method)

FIG. 12 is a process diagram of yet another modified electrolytic product collection method in this embodiment, and FIG. 13 is a diagram showing the configuration of an electrolytic product collection system that is applied to the yet another modified electrolytic product collection method shown in FIG. 12.

As shown in FIG. 11, the main difference between the electrolytic product extraction method of this modified example and the electrolytic product extraction method of the present embodiment described above is that the order of the extraction step 104 and the crushing step 105 is reversed, and the crushing step 105' is performed after the peeling step 103 and before the extraction step 104.

Specifically, in the crushing step 105', the zinc electrodeposits 4 deposited (electrodeposited) on each electrodeposited surface 28 of the electrode 22 of the cathode 20 in the electrolysis step 102, and the zinc electrodeposits 4 protruding and adhering to the portions of the masking member 26 adjacent to each electrodeposited surface 28, and the zinc flakes 5 peeled off from the electrodeposited surface 28 and masking member 26 in the peeling step 103 are crushed to a predetermined size. Then, in the next extraction step 104, the zinc flakes 7 that have descended through the electrolytic bath 32 to reach the storage section 34 and reached the bottom of the storage section 34 while being crushed in the crushing step 105' are extracted from the bottom of the storage section 34 to the outside of the electrolytic cell 30.

More specifically, as shown in FIG. 13, in the electrolytic product extraction system S1''' typically applied to the electrolytic product extraction method of this modified example, a crushing member 72' that crushes the zinc flakes 5 that have reached the storage section 34' of the electrolytic cell 30 into a predetermined size is provided in the storage section 34', and the storage section 34' also functions as a crusher 70'. The zinc flakes 7 crushed by the crushing member 72' further descend through the storage section 34' to reach its bottom, are extracted from the storage section 34', and are sent to the rust inhibitor applicator 80 via the screw conveyor 60.

In the electrolytic product collection method of this modified example, the zinc electrodeposit 5 peeled off from the cathode 20 in the peeling process 103 is crushed before being removed from the electrolytic cell 30, so that electrolytically produced zinc of the required size can be collected while simplifying the system configuration.

The shape, arrangement, number, etc. of the components of the present invention are not limited to those of the above-mentioned embodiment, and such components can of course be appropriately modified within the scope of the gist of the invention, such as by appropriately replacing such components with components that provide equivalent effects.

As described above, the present invention provides an electrolytic product extraction method and an electrolytic product extraction system that can adhere electrolytically generated zinc to the cathode surface of an electrolytic device while taking into consideration the extractability of the electrolytic zinc, and then reliably and efficiently extract the adhered electrolytically generated zinc. Because of its versatile and universal nature, it is expected to be applicable when extracting zinc from zinc-containing dust such as primary or secondary dust such as blast furnace dust or blast furnace/converter dust, and ore burnt from zinc concentrate, in addition to electric furnace dust generated during the melting and smelting of scrap in the electric furnace process, which is one of the iron-making processes.

101... Aqueous solution preparation process 102... Electrolysis process 103... Peeling process 103'... Vibration peeling process 104, 104'... Extraction process 105, 105'... Crushing process 106... Rust prevention process 107... Molding process S1, S1', S1'' S2, S3... Electrolysis product collection system E... Electrolysis device 1... Raw material 2... Sodium hydroxide aqueous solution 2'... Electrolytic tail solution 3... Zinc-containing sodium hydroxide aqueous solution 4... Zinc electrodeposit 5... Zinc peeling material 6... Transported zinc peeling material 7... Crushed zinc peeling material 8... Zinc peeling material coated with rust inhibitor (metallic zinc)
8'...Compression-molded zinc (metallic zinc)
Description of the Related Art 9...rust inhibitor 10...anode 12...electrode 14...cross member 20...cathode 22...electrode 24...cross member 26...insulating member 26a...base 26b...tooth portion 28...electrodeposition surface 30...electrolytic cell 32...electrolytic bath 34, 34'...storage section 40...peel-off mechanism 42...frame member 44...contact member 46...hammer device 50...power source 52, 54...bus bar 60...screw conveyor 62...screw member 64...inlet container 66...outlet container 70, 70'...disintegrator 72, 72'...disintegrator member 80...rust inhibitor applicator 82...centrifuge 90...circulation tank 92...pump 110...packet conveyor 112...packet member 114...belt 116...roller 120...pump 122...valve 124...receiving container 130...press molding device

Claims (9)

a step of preparing an aqueous solution for leaching a zinc-containing substance derived from the zinc-containing dust with an aqueous sodium hydroxide solution to obtain an aqueous zinc-containing sodium hydroxide solution;
an electrolysis step of performing electrolysis using an electrolysis device including an anode, a cathode made of pure magnesium or a magnesium alloy facing the anode, and an electrolysis cell containing an electrolysis bath using the zinc-containing sodium hydroxide aqueous solution;
and a peeling step in which, inside the electrolytic cell, a contact member is brought into contact with each of a plurality of portions of the zinc electrodeposit obtained as an electrolytic product in the electrolysis step in sequence at predetermined time intervals to peel off the zinc electrodeposit from the cathode. The electrolytic product extraction method according to claim 1, wherein the zinc electrodeposit is a powder or a dendritic crystal, and the current density applied to the electrolysis at the start of the electrolysis step is greater than the current density applied to the electrolysis after the start of the electrolysis. The electrolytic product collection method according to claim 1 or 2, in which the electrodeposition surface on which the zinc electrodeposit is electrodeposited on the cathode is set as a plurality of electrodeposition surfaces that are separated from one another. The electrolytic product extraction method according to claim 3, wherein in the peeling step, the contact member is moved while being in contact with a portion of the zinc electrodeposits electrodeposited on the plurality of electrodeposition surfaces, and then, after the predetermined time interval, the contact member is moved while being in contact with the remaining portion of the zinc electrodeposits electrodeposited on the plurality of electrodeposition surfaces. The electrolytic product collection method according to claim 3, wherein in the peeling process, the cathode is vibrated when the contact member is brought into contact with the zinc electrodeposit. The electrolytic product extraction method according to claim 1 or 2, wherein the zinc electrodeposits peeled off from the cathode in the peeling process are crushed before or after being removed from the electrolytic cell. The electrolytic product collection method according to claim 1 or 2, wherein the zinc electrodeposits peeled off from the cathode in the peeling process are washed with water after being removed from the electrolytic cell, and a rust inhibitor is applied to the washed zinc electrodeposits. The electrolytic product extraction method according to claim 1 or 2, further comprising a compression molding step in which the zinc electrodeposit peeled off from the cathode in the peeling step is washed with water after being removed from the electrolytic cell, and the washed zinc electrodeposit is compression molded. An electrolysis product collection system comprising: an electrolysis device having an anode, a cathode made of pure magnesium or a magnesium alloy facing the anode, and an electrolysis cell containing an electrolysis bath using an aqueous zinc-containing sodium hydroxide solution obtained by leaching zinc-containing material derived from zinc-containing dust with an aqueous sodium hydroxide solution; and a peeling mechanism having a contact member that, in the electrolysis cell, sequentially contacts each of a plurality of portions of the zinc electrodeposit obtained as an electrolysis product in the electrolysis process at predetermined time intervals to peel off the zinc electrodeposit from the cathode.

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