Dissolution tank and method for producing nickel chloride aqueous solution

Abstract

To provide a dissolving tank capable of enhancing efficiency of a chlorine leaching reaction of a nickel raw material and a method for manufacturing an aqueous solution of nickel chloride.SOLUTION: A dissolving tank 1 includes a tank main body 10, a screen plate 15 provided inside the tank main body 10 and on which a nickel raw material N is placed, an injection part 21 that sprays a liquid on the nickel raw material N, a chlorine gas supply tube 52 that supplies the chlorine gas to inside of the tank main body 10, and a drain port 18 provided below the screen plate 15 to discharge the generated nickel chloride aqueous solution by overflow. Since the nickel raw material N is covered with a liquid film under a chlorine gas atmosphere, the chlorine gas is easily absorbed into the liquid, and the chlorine leaching reaction of the nickel raw material N is likely to proceed. Therefore, a nickel chloride aqueous solution can be generated with high efficiency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dissolving tank and a method for producing an aqueous nickel chloride solution. More particularly, the present invention relates to a dissolving tank and a method for producing an aqueous nickel chloride solution by chlorine leaching a nickel raw material. [Background technology]

[0002] Nickel chloride is used in nickel plating. Nickel chloride is also used as an electrode material for multilayer ceramic capacitors and as a raw material for nickel powder for conductive pastes. Nickel chloride may be an aqueous solution of nickel chloride or nickel chloride crystals obtained by crystallizing the aqueous solution of nickel chloride.

[0003] Patent Documents 1 and 2 disclose a method for obtaining an aqueous nickel chloride solution by dissolving a nickel raw material in hydrochloric acid, and Patent Document 3 discloses a method for obtaining an aqueous nickel chloride solution by chlorine leaching a nickel raw material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-152592 [Patent Document 2] Special Publication No. 7-507036 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-121370 Summary of the Invention [Problem to be solved by the invention]

[0005] In practical operations for producing aqueous nickel chloride solutions, efficient operation is required, and therefore the efficiency of the chlorine leaching reaction of the nickel raw material is required to be high.

[0006] In view of the above circumstances, an object of the present invention is to provide a dissolving tank and a method for producing an aqueous nickel chloride solution that can increase the efficiency of the chlorine leaching reaction of a nickel raw material. [Means for solving the problem]

[0007] The dissolution tank of the first invention is characterized by comprising: a tank body; a drain plate provided inside the tank body and on which a nickel raw material is placed; a spray unit that sprays a liquid onto the nickel raw material; a chlorine gas supply pipe that supplies chlorine gas into the tank body; and a drain port that is provided below the drain plate and through which the produced aqueous nickel chloride solution is discharged by overflow. The dissolution tank of the second invention is characterized in that, in the first invention, it further comprises a small circulation pipe for extracting the aqueous nickel chloride solution from the bottom of the tank body and circulating it to the spray section. The dissolution tank of the third invention is the same as that of the first invention, wherein the drainboard is provided so as to divide the tank body into upper and lower sections. The melting tank of the fourth invention is the same as that of the first invention, further comprising a top plate having a charging port for charging the nickel raw material, the injection unit consisting of a small annular pipe and a large annular pipe arranged concentrically and provided on the underside of the top plate, and the charging port being located inside the small annular pipe. The dissolution tank of the fifth invention is the dissolution tank of the second invention, characterized in that it further comprises a heat exchanger provided in the small circulation pipe for cooling the aqueous nickel chloride solution. The method for producing an aqueous nickel chloride solution according to the sixth aspect of the present invention is characterized in that the nickel raw material is chlorine-leached by spraying a liquid onto the nickel raw material in a chlorine gas atmosphere, thereby producing an aqueous nickel chloride solution. A seventh aspect of the present invention is a method for producing an aqueous nickel chloride solution according to the sixth aspect of the present invention, characterized in that the nickel raw material is electrolytic nickel. [Effects of the Invention]

[0008] According to the first aspect of the present invention, the nickel raw material is covered with a liquid film in a chlorine gas atmosphere, which facilitates absorption of the chlorine gas into the liquid and facilitates the chlorine leaching reaction of the nickel raw material, thereby enabling highly efficient production of an aqueous nickel chloride solution. According to the second invention, a highly concentrated aqueous nickel chloride solution can be obtained by subjecting the aqueous nickel chloride solution to chlorine leaching while circulating it. In addition, gravity can be used to constantly bring fresh solution into contact with the nickel raw material, allowing for more efficient production of the aqueous nickel chloride solution. According to the third aspect of the present invention, since the drain board is provided across the tank body, the nickel raw material can be placed on the drain board simply by adding it from the top of the drain board. In addition, since the amount of nickel raw material held in the tank can be increased, the nickel chloride aqueous solution can be produced more efficiently. According to the fourth aspect of the present invention, the injection section does not get in the way when the nickel raw material is charged, and the liquid can be sprayed over the entire nickel raw material. According to the fifth aspect of the present invention, it is possible to suppress the temperature rise due to the heat of reaction, thereby protecting the dissolution tank. In addition, by cooling the aqueous nickel chloride solution, chlorine gas is easily absorbed into the liquid, facilitating the chlorine leaching reaction, which is an exothermic reaction. According to the sixth aspect of the present invention, the nickel raw material is covered with a liquid film in a chlorine gas atmosphere, which facilitates absorption of the chlorine gas into the liquid and facilitates the chlorine leaching reaction of the nickel raw material, thereby enabling highly efficient production of an aqueous nickel chloride solution. According to the seventh aspect of the present invention, a highly pure aqueous nickel chloride solution can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a vertical cross-sectional view of a dissolution tank according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along the line II-II in FIG. [Figure 3] FIG. 1 is an overall configuration diagram of a manufacturing facility. [Figure 4] FIG. 2 is a vertical cross-sectional view of the starting liquid tank. [Figure 5] FIG. 2 is an explanatory diagram showing the state of the dissolution tank during (1) the raw material charging process and (2) the liquid supply process. [Figure 6] FIG. 3 is an explanatory diagram showing the state of the dissolution tank in (3) the decompression step and (4) the chlorine gas supply step. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, an embodiment of the present invention will be described with reference to the drawings. (dissolving tank) The dissolution tank according to one embodiment of the present invention is a tank for producing an aqueous nickel chloride solution by chlorine leaching of a nickel raw material. The nickel raw material is not particularly limited as long as it contains nickel. However, if electrolytic nickel is used as the nickel raw material, a high-purity aqueous nickel chloride solution can be obtained.

[0011] Electrolytic nickel can be produced, for example, by nickel hydrometallurgy. In nickel hydrometallurgy, raw materials such as nickel matte and nickel-cobalt mixed sulfide are leached with chlorine. The leachate is purified to remove impurities, yielding an aqueous nickel chloride solution. Electrolytic nickel can be obtained by electrowinning using the aqueous nickel chloride solution as the electrolyte.

[0012] To increase the dissolution efficiency, it is preferable to use small electrolytic nickel. For example, it is preferable to use plate-shaped electrolytic nickel cut to dimensions of 100 mm x 100 mm or less. Button-shaped electrolytic nickel may also be used. The smaller the electrolytic nickel size, the larger the contact area with the nickel chloride aqueous solution, and therefore the more efficiently chlorine leaching will proceed.

[0013] As shown in Fig. 1, the dissolution tank 1 has a tank body 10. The tank body 10 is preferably an airtight tank. The shape of the tank body 10 is not particularly limited, and may be cylindrical or rectangular.

[0014] A charging port 12 is provided in the center of the top plate of the tank body 10. Nickel raw material N is charged into the tank body 10 through the charging port 12. The charging port 12 is closed with a lid 13. A water seal is provided between the charging port 12 and the lid 13 to seal the space between them. Therefore, by closing the charging port 12 with the lid 13 and sealing it with water, the tank body 10 can be made airtight.

[0015] A drain plate 15 is provided inside the tank body 10. The drain plate 15 is installed horizontally across the tank body 10 near the center of the top and bottom. The interior space of the tank body 10 is divided into two spaces, an upper space and an lower space, by the drain plate 15. A plate material with multiple holes or slits, such as a punched plate or a wedge wire screen, is used as the drain plate 15. The nickel raw material N charged through the charging port 12 is placed on the drain plate 15. Meanwhile, the liquid passes through the drain plate 15 and flows down from the upper space of the tank body 10 to the lower space.

[0016] Since the drain board 15 is provided across the tank body 10, the nickel raw material N can be placed on the drain board 15 simply by adding it from the top of the drain board 15. In addition, since the amount of nickel raw material N held in the dissolution tank 1 can be increased, the nickel chloride aqueous solution can be produced more efficiently.

[0017] A liquid supply port 16 is provided on the top plate of the tank body 10. The liquid supply port 16 is connected to a liquid supply device. The dissolution liquid supplied from the liquid supply device flows into the tank body 10 from the liquid supply port 16. The liquid supply device will be described in detail later.

[0018] The side wall of the tank body 10 is provided with an overflow port 17 at the top and a drain port 18 at the bottom. The overflow port 17 is located above the drain board 15 and close to the top plate of the tank body 10. On the other hand, the drain port 18 is located below the drain board 15 and close to the drain board 15. Both the overflow port 17 and the drain port 18 are used to drain the liquid inside the tank body 10.

[0019] An outlet 19 is further provided on the side wall of the tank body 10. The outlet 19 is provided below the drainage port 18 and near the bottom of the tank body 10. A return port 20 is provided on the top plate of the tank body 10.

[0020] The outlet 19 and the return port 20 are connected by a small circulation pipe 51. A small circulation pump 71 is provided in the small circulation pipe 51. The suction side of the small circulation pump 71 is connected to the outlet 19, and the discharge side is connected to the return port 20. Therefore, when the small circulation pump 71 is driven, liquid is extracted from the bottom of the tank body 10 and can be returned to the top of the tank body 10.

[0021] A heat exchanger 73 is provided in the small circulation pipe 51. The heat exchanger 73 cools the liquid flowing through the small circulation pipe 51. Therefore, the liquid extracted from the tank body 10 is returned to the tank body 10 after being cooled.

[0022] A spray unit 21 is provided inside the tank body 10 near the underside of the top plate. The return port 20 is connected to the spray unit 21. The liquid circulated through the small circulation pipe 51 is sprayed from the spray unit 21 and wets the nickel raw material N.

[0023] As shown in FIG. 2, the spray unit 21 consists of a small annular pipe 21a and a large annular pipe 21b arranged concentrically. The small annular pipe 21a and the large annular pipe 21b each have a plurality of holes at predetermined intervals, through which the liquid is sprayed. Since the spray unit 21 is arranged across the entire cross section of the tank body 10, the liquid can be sprayed over the entire nickel raw material N. The charging port 12 is arranged inside the small annular pipe 21a. Therefore, the spray unit 21 does not get in the way when charging the nickel raw material N.

[0024] In this embodiment, the dissolution starting liquid flows directly down from the liquid supply port 16. Alternatively, the liquid supply port 16 may be connected to a spray unit. This spray unit may be the same as the spray unit 21 connected to the return port 20, or may be a separate member. If the liquid supply port 16 is connected to the spray unit, the dissolution starting liquid can be sprayed onto the nickel raw material N.

[0025] As shown in FIG. 1 , a chlorine gas supply pipe 52 is connected to the tank body 10. The open end of the chlorine gas supply pipe 52 is located inside the tank body 10, below the drainboard 15. The other end of the chlorine gas supply pipe 52 is connected to a chlorine gas supply source 74. A gas cylinder filled with liquefied chlorine can be used as the chlorine gas supply source 74. A flow control valve 61 is provided on the chlorine gas supply pipe 52. Chlorine gas can be supplied into the tank body 10 through the chlorine gas supply pipe 52. The amount of chlorine gas supplied can be adjusted by adjusting the aperture of the flow control valve 61. The chlorine gas supply pipe 52, the flow control valve 61, and the chlorine gas supply source 74 constitute a chlorine gas supply device that supplies chlorine gas to the dissolution tank 1.

[0026] A pressure gauge 22 is provided on the top plate of the tank body 10. The pressure of the gas phase in the dissolution tank 1 can be measured by the pressure gauge 22.

[0027] An annular collection port 23 is provided on the top plate of the tank body 10. An annular collection pipe 53 is connected to the annular collection port 23. An exhaust valve 62 is provided on the annular collection pipe 53. Opening the exhaust valve 62 allows the gas inside the tank body 10 to be exhausted. Closing the exhaust valve 62 makes the tank body 10 airtight.

[0028] The gas phase in the dissolution tank 1 is filled with chlorine gas supplied from the chlorine gas supply pipe 52. Furthermore, the nickel raw material N is wetted by the liquid sprayed from the spray unit 21. As a result, the nickel raw material N is covered with a liquid film in a chlorine gas atmosphere. The chlorine gas is absorbed by the liquid covering the nickel raw material N, and the chlorine leaching reaction of the nickel raw material N progresses, producing an aqueous nickel chloride solution. In this way, the nickel raw material N is chlorine-leached in the dissolution tank 1, producing an aqueous nickel chloride solution. The produced aqueous nickel chloride solution is temporarily stored in the lower part of the dissolution tank 1 and is discharged from the drain port 18 or the extraction port 19.

[0029] (manufacturing equipment) The dissolution tank 1 is not particularly limited, but can be incorporated into a manufacturing facility AA for producing an aqueous nickel chloride solution as shown in Fig. 3. The manufacturing facility AA has the dissolution tank 1, an initial liquid tank 2, an adjustment tank 3, and a final liquid tank 4. The manufacturing facility AA also has a control device 5 that acquires measurements from various measuring instruments and controls the operation of various valves, pumps, etc. A computer such as a PLC can be used as the control device 5.

[0030] As shown in FIG. 4, the starting liquid tank 2 is a tank for storing the dissolution starting liquid. The dissolution starting liquid is a nickel chloride aqueous solution or water. The water used as the dissolution starting liquid is preferably pure water. This allows for the production of a highly pure nickel chloride aqueous solution. The shape of the starting liquid tank 2 is not particularly limited, and it may be cylindrical or rectangular. Furthermore, unlike the dissolution tank 1, the starting liquid tank 2 does not require airtightness. However, since chlorine gas is dissolved in the dissolution starting liquid during steady-state operation, it is preferable that the gas phase of the starting liquid tank 2 is also circulated.

[0031] A liquid outlet 31 and a liquid inlet 32 ​​are provided at the bottom of the initial liquid tank 2. In addition, a water addition port 33 and a hydrochloric acid addition port 34 are provided on the top plate of the initial liquid tank 2. The initial liquid tank 2 has an agitator 35. The dissolution initial liquid can be agitated by driving the agitator 35. The initial liquid tank 2 is provided with a pH meter 36. The pH of the dissolution initial liquid can be measured using the pH meter 36. The initial liquid tank 2 is provided with a level meter 37. The liquid level in the initial liquid tank 2 can be measured using the level meter 37.

[0032] As shown in Figure 3, one end of a liquid supply pipe 54 is connected to the liquid outlet 31 of the initial liquid tank 2. The other end of the liquid supply pipe 54 is connected to the liquid supply port 16 of the dissolution tank 1. A liquid supply pump 72 is provided on the liquid supply pipe 54. When the liquid supply pump 72 is driven, the dissolution initial liquid in the initial liquid tank 2 is supplied to the dissolution tank 1. Therefore, the initial liquid tank 2, the liquid supply pipe 54, and the liquid supply pump 72 constitute a liquid supply device that supplies the dissolution initial liquid to the dissolution tank 1.

[0033] One end of drain pipe 55 is connected to liquid inlet 32 ​​of starting liquid tank 2. The other end of drain pipe 55 is connected to drain port 18 of dissolution tank 1. Drain pipe 55 is provided with drain valve 63. Therefore, when drain valve 63 is opened, the aqueous nickel chloride solution produced in dissolution tank 1 is discharged through drain pipe 55 into starting liquid tank 2. Supply pipe 54 and drain pipe 55 form a large circulation flow path that circulates the liquid between starting liquid tank 2 and dissolution tank 1.

[0034] One end of an overflow pipe 56 is connected to the overflow port 17 of the dissolution tank 1. The other end of the overflow pipe 56 is connected to the downstream side (the starting liquid tank 2 side) of the drain valve 63 of the drain pipe 55. The liquid overflowing from the overflow port 17 of the dissolution tank 1 is discharged into the starting liquid tank 2 via the overflow pipe 56 and the drain pipe 55.

[0035] As shown in Figure 4, the starting liquid tank 2 is provided with a water addition device. The water addition device has a water supply source 75, a water supply pipe 57, and a flow control valve 64. A tank for storing water, a utility pipe within a factory, or the like can be used as the water supply source 75. The water supply pipe 57 connects the water supply source 75 with the water addition port 33 of the starting liquid tank 2. The flow control valve 64 is provided in the water supply pipe 57 and controls the amount of water supplied to the starting liquid tank 2.

[0036] By adding water to the starting liquid tank 2 using the water adding device, water can be added to the aqueous nickel chloride solution that has returned from the dissolution tank 1 to the starting liquid tank 2. The concentration of the aqueous nickel chloride solution can be adjusted by adding water. Here, the concentration of the aqueous nickel chloride solution in the starting liquid tank 2 can be made uniform by stirring with the stirrer 35. Note that if pure water is used as the water to be added, it is possible to prevent impurities from being mixed into the aqueous nickel chloride solution.

[0037] A hydrochloric acid addition device is provided in the starting liquid tank 2. The hydrochloric acid addition device has a hydrochloric acid supply source 76, a hydrochloric acid supply pipe 58, and a flow control valve 65. A tank for storing hydrochloric acid, a utility pipe within a factory, or the like can be used as the hydrochloric acid supply source 76. The hydrochloric acid supply pipe 58 connects the hydrochloric acid supply source 76 to the hydrochloric acid addition port 34 of the starting liquid tank 2. The flow control valve 65 is provided in the hydrochloric acid supply pipe 58 and controls the amount of hydrochloric acid supplied to the starting liquid tank 2.

[0038] By adding hydrochloric acid to the initial liquid tank 2 using the hydrochloric acid adding device, hydrochloric acid can be added to the aqueous nickel chloride solution that has returned from the dissolution tank 1 to the initial liquid tank 2. The pH of the aqueous nickel chloride solution can be adjusted by adding hydrochloric acid. Here, the pH of the aqueous nickel chloride solution in the initial liquid tank 2 can be made uniform by stirring with the stirrer 35. The pH of the aqueous nickel chloride solution can also be measured with the pH meter 36.

[0039] As shown in Fig. 3, the manufacturing equipment AA has a drainage device that discharges the produced aqueous nickel chloride solution. The drainage device has a dispensing pipe 59 and a flow control valve 66. One end of the dispensing pipe 59 is connected to the downstream side (dissolution tank 1 side) of the feed pump 72 of the feed pipe 54. The other end of the dispensing pipe 59 is connected to the final liquid tank 4. A flow control valve 66 is provided on the dispensing pipe 59. When the flow control valve 66 is opened, a portion of the aqueous nickel chloride solution flowing through the feed pipe 54 flows through the dispensing pipe 59 and is led to the final liquid tank 4.

[0040] An adjustment tank 3 is provided midway along the discharge pipe 59. The adjustment tank 3 is filled with nickel raw material. The nickel chloride aqueous solution produced in the dissolution tank 1 contains dissolved chlorine gas. When this nickel chloride aqueous solution is passed through the adjustment tank 3, the chlorine gas dissolved in the nickel chloride aqueous solution leaches the nickel raw material in the adjustment tank 3. The chlorine gas dissolved in the nickel chloride aqueous solution is consumed in the leaching of the nickel raw material, thereby removing the chlorine gas from the nickel chloride aqueous solution. This reduces the amount of impurities that are mixed into the nickel chloride aqueous solution compared to removing dissolved chlorine gas using a chemical such as a reducing agent. Electrolytic nickel is preferably used as the nickel raw material filled into the adjustment tank 3. Because electrolytic nickel is a highly pure nickel, it further reduces the amount of impurities that are mixed into the nickel chloride aqueous solution. The nickel chloride aqueous solution that has passed through the adjustment tank 3 is stored in the final liquid tank 4.

[0041] (Manufacturing method) Next, a method for producing an aqueous nickel chloride solution using the dissolution tank 1 will be described.

[0042] (1) Raw material charging process In the dissolution tank 1, nickel raw material N is chlorine-leached by batch processing to produce a nickel chloride aqueous solution. As shown in Figure 5 (1), at the start of the batch processing, the lid 13 of the dissolution tank 1 is removed and the nickel raw material N is charged through the charging port 12. The nickel raw material N is piled up on the sieve board 15. After the nickel raw material N is charged, the charging port 12 is closed with the lid 13. Then, the space between the charging port 12 and the lid 13 is sealed with water.

[0043] (2) Liquid supply process Next, as shown in Figure 5 (2), the exhaust valve 62 of the annular collection pipe 53 is opened. The liquid supply pump 72 is driven to supply the dissolving starting liquid in the starting liquid tank 2 to the dissolving tank 1 (see Figure 3). When no nickel chloride aqueous solution remains, such as when the manufacturing equipment AA is operated for the first time, the dissolving starting liquid in the starting liquid tank 2 is water, preferably pure water. During steady operation in which batch treatments are repeatedly performed, the dissolving starting liquid in the starting liquid tank 2 is the nickel chloride aqueous solution produced in the previous batch treatment.

[0044] The dissolution starting liquid is supplied to the dissolution tank 1 from the liquid supply port 16. As the liquid level in the dissolution tank 1 is supplied, it gradually rises. As a result, the air in the gas phase in the dissolution tank 1 is exhausted from the annular collection pipe 53. When the liquid level in the dissolution tank 1 reaches the height of the overflow port 17, the dissolution starting liquid is discharged from the overflow port 17. At this point, most of the air present in the dissolution tank 1 is exhausted. The dissolution starting liquid discharged from the overflow port 17 is returned to the dissolution starting tank 2 via the overflow pipe 56 and the drain pipe 55 (see Figure 3). The supply of the dissolution starting liquid from the liquid supply port 16 continues until the batch processing is completed.

[0045] Furthermore, the small circulation pump 71 is driven to extract the liquid from the extraction port 19 and spray it from the spray unit 21. This circulation of the liquid also continues until the batch processing is completed.

[0046] (3) Decompression process Next, as shown in Figure 6 (3), the exhaust valve 62 of the annular collection pipe 53 is closed to seal the dissolution tank 1. Then, the drain valve 63 is opened to return the dissolution starting liquid in the dissolution tank 1 to the starting liquid tank 2 via the drain pipe 55 (see Figure 3). When the drain valve 63 of the drain pipe 55 is opened, the dissolution starting liquid is discharged from the drain port 18 located at the bottom of the dissolution tank 1. As a result, the liquid level in the dissolution tank 1 gradually drops. Because the dissolution tank 1 is sealed, the pressure in the gas phase gradually drops as the liquid level drops, creating a negative pressure. In this way, after the dissolution tank 1 is filled with the dissolution starting liquid, the dissolution tank 1 is sealed and the liquid level of the dissolution starting liquid is lowered, creating a negative pressure inside the dissolution tank 1.

[0047] (4) Chlorine gas supply process At the same time as or immediately after opening the drain valve 63 of the drain pipe 55, the supply of chlorine gas to the dissolution tank 1 is started. As shown in Figure 6 (4), the supply of chlorine gas is carried out by opening the flow control valve 61 of the chlorine gas supply pipe 52. As the liquid level in the dissolution tank 1 drops, chlorine gas is supplied, and the gas phase in the dissolution tank 1 becomes a chlorine gas atmosphere. The supply of chlorine gas continues until the batch processing is completed.

[0048] Here, the supply rate of chlorine gas is preferably controlled so that the pressure in the gas phase in the dissolution tank 1 remains constant at a predetermined pressure. The pressure in the gas phase in the dissolution tank 1 can be measured by a pressure gauge 22. The control device 5 acquires the measured value from the pressure gauge 22 and controls the aperture of the flow control valve 61 so that the measured value remains constant at the predetermined pressure, thereby adjusting the supply rate of chlorine gas. For example, the control device 5 performs feedback control using the pressure in the gas phase in the dissolution tank 1 as the controlled variable and the supply rate of chlorine gas as the manipulated variable. The target value of the pressure in the gas phase in the dissolution tank 1 is set, for example, between -1 and -3 kPa.

[0049] The liquid level in the dissolution tank 1 drops to the height of the drain outlet 18 and becomes constant at this level. At this time, the position of the open end of the chlorine gas supply pipe 52 (the outlet for chlorine gas) may be higher than the liquid level, may be the same as the liquid level, or may be lower than the liquid level. In other words, chlorine gas may be supplied directly to the gas phase in the dissolution tank 1, or may be supplied into the liquid in the dissolution tank 1.

[0050] (5) Leaching process When the supply of chlorine gas begins, the chlorine leaching reaction of the nickel raw material N begins. The gas phase in the dissolution tank 1 is filled with chlorine gas. The nickel raw material N is also wetted by the liquid sprayed from the spray unit 21. As a result, the nickel raw material N is covered with a liquid film in a chlorine gas atmosphere. The chlorine gas is absorbed by the liquid covering the nickel raw material N, the chlorine leaching reaction of the nickel raw material N progresses, and an aqueous nickel chloride solution is produced. The produced aqueous nickel chloride solution is temporarily stored in the lower part of the dissolution tank 1. A portion of this aqueous nickel chloride solution is discharged from the drain port 18 and circulates between the dissolution tank 1 and the starting liquid tank 2 via the large circulation flow paths 55 and 54. Another portion of the aqueous nickel chloride solution circulates through the small circulation pipe 51 and is sprayed from the spray unit 21.

[0051] The produced aqueous nickel chloride solution is discharged from the drain outlet 18 by overflow. Therefore, the liquid level of the aqueous nickel chloride solution is the height of the drain outlet 18. The nickel raw material N is placed above the liquid surface, i.e., in the gas phase which is in a chlorine gas atmosphere. By spraying the liquid onto the nickel raw material N in a chlorine gas atmosphere, the nickel raw material N is chlorine-leached to produce an aqueous nickel chloride solution. Because the nickel raw material N is covered with a liquid film in a chlorine gas atmosphere, the chlorine gas is easily absorbed by the liquid, and the chlorine leaching reaction of the nickel raw material N progresses easily. Therefore, the aqueous nickel chloride solution can be produced more efficiently than when the nickel raw material N is immersed in liquid.

[0052] Furthermore, the aqueous nickel chloride solution is extracted from the bottom of the tank body 10 via the small circulation pipe 51 and circulated to the injection section 21. By subjecting the aqueous nickel chloride solution to chlorine leaching while circulating it, a highly concentrated aqueous nickel chloride solution can be obtained. Furthermore, by using gravity to constantly bring fresh solution into contact with the nickel raw material N, the aqueous nickel chloride solution can be produced more efficiently.

[0053] Chlorine gas is consumed by the chlorine leaching reaction of the nickel raw material N, and the pressure in the gas phase in the dissolution tank 1 decreases accordingly. However, when the amount of chlorine gas supplied is controlled based on the pressure in the gas phase in the dissolution tank 1, chlorine gas is supplied in an amount that keeps the pressure in the gas phase in the dissolution tank 1 constant. In other words, the amount of chlorine gas consumed in the chlorine leaching reaction is newly supplied.

[0054] (6) Temperature adjustment process The chlorine leaching reaction of the nickel raw material N is an exothermic reaction. Therefore, if left unchecked, the temperature of the nickel chloride aqueous solution in the dissolution tank 1 will rise as the chlorine leaching reaction progresses. However, as shown in Figure 1, a heat exchanger 73 is provided in the small circulation pipe 51 through which the nickel chloride aqueous solution circulates. The heat exchanger 73 can cool the nickel chloride aqueous solution. The heat exchanger 73 adjusts the nickel chloride aqueous solution to a temperature appropriate for equipment protection, for example, 50 to 60°C. This makes it possible to suppress temperature increases due to the heat of reaction and protect the dissolution tank 1. Furthermore, cooling the nickel chloride aqueous solution makes it easier for chlorine gas to be absorbed into the liquid, facilitating the progress of the chlorine leaching reaction, which is an exothermic reaction.

[0055] (7) Water addition process The chlorine leaching reaction of the nickel raw material N proceeds continuously in the dissolution tank 1. Therefore, the nickel concentration in the aqueous nickel chloride solution gradually increases. Therefore, it is preferable to adjust the nickel concentration in the aqueous nickel chloride solution by adding water, preferably pure water, to the aqueous nickel chloride solution.

[0056] 4, water is added to the initial liquid tank 2. As a result, water is added to the aqueous nickel chloride solution returned from the dissolution tank 1 to the initial liquid tank 2. Here, it is preferable that the control device 5 adjusts the amount of water added to the aqueous nickel chloride solution to an amount determined based on the amount of chlorine gas supplied to the dissolution tank 1.

[0057] The ratio between the amount of chlorine gas consumed in the chlorine leaching reaction and the amount of nickel leached is known. Therefore, the amount of water added can be made proportional to the amount of chlorine gas supplied. Specifically, the control device 5 sets a target value obtained by multiplying the amount of chlorine gas supplied by a predetermined coefficient, and adjusts the aperture of the flow control valve 64 of the water supply pipe 57 so that the amount of water added reaches the target value.

[0058] The nickel concentration of the nickel chloride aqueous solution is adjusted to a desired concentration by adding water. For example, the nickel concentration of the nickel chloride aqueous solution is adjusted to a predetermined value between 130 and 160 g / L. The nickel concentration of the nickel chloride aqueous solution may be periodically measured using a hydrometer or the like, and the coefficient by which the supply amount of chlorine gas is multiplied to determine the amount of water to be added may be adjusted as needed.

[0059] Water may be added to the aqueous nickel chloride solution in the dissolution tank 1. However, if water is added to the starting solution tank 2 as in this embodiment, the concentration of the aqueous nickel chloride solution can be easily made uniform.

[0060] (8) pH adjustment process It is preferable to adjust the pH by adding hydrochloric acid to the aqueous nickel chloride solution. In this embodiment, as shown in FIG. 4, hydrochloric acid is added to the starting solution tank 2. Here, it is preferable to adjust the pH of the aqueous nickel chloride solution to 1 to 3. The pH of the aqueous nickel chloride solution in the starting solution tank 2 can be measured by a pH meter 36. The control device 5 acquires the measured value from the pH meter 36 and controls the aperture of the flow control valve 65 of the hydrochloric acid supply pipe 58 so that the measured value becomes a predetermined target value, thereby adjusting the supply amount of hydrochloric acid. For example, the control device 5 performs feedback control using the pH of the aqueous nickel chloride solution as a controlled variable and the supply amount of hydrochloric acid as a manipulated variable.

[0061] If the pH of the nickel chloride aqueous solution is maintained at 1 to 3, the oxidation neutralization reaction of the nickel chloride aqueous solution does not occur, and therefore, the generation of hydroxides and oxides due to the oxidation neutralization reaction can be suppressed.

[0062] (9) Drainage process The addition of water and hydrochloric acid causes the liquid level in the initial liquid tank 2 to rise. Furthermore, an aqueous solution of nickel chloride with adjusted nickel concentration and pH is stored in the initial liquid tank 2. This adjusted aqueous solution of nickel chloride is discharged from the initial liquid tank 2. The aqueous solution of nickel chloride is discharged using a drainage device.

[0063] As shown in Figure 3, the drainage device has a discharge pipe 59 and a flow control valve 66. A prepared aqueous nickel chloride solution flows through the liquid supply pipe 54. By opening the flow control valve 66, a portion of the aqueous nickel chloride solution flowing through the liquid supply pipe 54 flows into the discharge pipe 59 and is led to the final liquid tank 4.

[0064] Here, it is preferable that the control device 5 adjusts the amount of nickel chloride aqueous solution discharged so that the liquid level in the initial liquid tank 2 is constant. Specifically, the liquid level in the initial liquid tank 2 can be measured by a level gauge 37. The control device 5 acquires the measured value from the level gauge 37 and controls the aperture of the flow control valve 66 of the dispensing pipe 59 so that the measured value becomes constant at a predetermined value, thereby adjusting the amount of nickel chloride aqueous solution discharged. For example, the control device 5 performs feedback control using the liquid level in the initial liquid tank 2 as a controlled variable and the discharge amount of nickel chloride aqueous solution as a manipulated variable. By performing such control, the produced amount of nickel chloride aqueous solution can be discharged.

[0065] (10) Dechlorination process The aqueous nickel chloride solution discharged from the starting tank 2 is supplied to the adjustment tank 3. The adjustment tank 3 is filled with nickel raw material. The aqueous nickel chloride solution produced in the dissolution tank 1 has dissolved chlorine gas. When this aqueous nickel chloride solution is passed through the adjustment tank 3, it comes into contact with the nickel raw material, and the nickel raw material is leached by the chlorine gas dissolved in the aqueous nickel chloride solution. The chlorine gas dissolved in the aqueous nickel chloride solution is consumed in the leaching of the nickel raw material, and the chlorine gas can be removed from the aqueous nickel chloride solution. The aqueous nickel chloride solution from which the dissolved chlorine gas has been removed after passing through the adjustment tank 3 is stored in the final tank 4.

[0066] The steps from (4) chlorine gas supply step to (10) chlorine gas removal step are carried out simultaneously. That is, as the chlorine leaching reaction of the nickel raw material N progresses, the produced nickel chloride aqueous solution is adjusted and discharged in proportion to the amount produced.

[0067] (11) Raw material recharging process As the chlorine leaching reaction progresses, the amount of nickel raw material N in the dissolution tank 1 decreases. When the amount of nickel raw material N decreases, the contact area with the nickel chloride aqueous solution decreases, and the dissolution rate slows down. Therefore, it is preferable to terminate the batch treatment with a certain amount of nickel raw material N remaining and recharge the nickel raw material N before the nickel raw material N in the dissolution tank 1 is completely consumed.

[0068] Specifically, the flow control valve 61 of the chlorine gas supply pipe 52 is closed to stop the supply of chlorine gas. Next, the exhaust valve 62 of the annular collection pipe 53 is opened to degas the chlorine gas in the dissolution tank 1. The chlorine gas discharged from the annular collection pipe 53 is led to a detoxification tower where it is detoxified. Furthermore, the small circulation pump 71 is stopped to stop the circulation of the nickel chloride aqueous solution in the dissolution tank 1, and the supply of the dissolution starting solution from the liquid supply pipe 54 to the dissolution tank 1 is stopped.

[0069] Degassing is completed after a certain time has passed since the exhaust valve 62 of the annular collection pipe 53 was opened. After that, the lid 13 of the dissolution tank 1 is removed, and new nickel raw material N is charged through the charging port 12. After that, a new batch process is carried out. That is, each step from (2) Liquid supply step to (10) Dechlorination gas step is repeatedly carried out.

[0070] Other Embodiments In the above-described embodiment, the aqueous nickel chloride solution in the dissolution tank 1 is circulated through the small circulation pipe 51 and sprayed onto the nickel raw material N from the spray unit 21. Alternatively, the aqueous nickel chloride solution circulating through the large circulation flow path between the dissolution tank 1 and the starting liquid tank 2 may be sprayed from the spray unit 21. In this case, the small circulation pipe 51 may be omitted. Furthermore, the temperature of the aqueous nickel chloride solution may be adjusted by a heat exchanger provided in the large circulation flow path.

[0071] In the above-described embodiment, chlorine leaching is performed under negative pressure in the dissolution tank 1, but chlorine leaching may also be performed under positive pressure. In either case, it is preferable to maintain the dissolution tank 1 airtight. This prevents chlorine gas from being discharged from the dissolution tank 1 while the chlorine leaching reaction is proceeding. Therefore, a large-scale chlorine gas removal device is not required.

[0072] The nickel concentration of the aqueous nickel chloride solution may be adjusted by adding water to the dissolution tank 1. Alternatively, the pH of the aqueous nickel chloride solution may be adjusted by adding hydrochloric acid to the dissolution tank 1. That is, the aqueous nickel chloride solution may be adjusted in the dissolution tank 1, and the adjusted aqueous nickel chloride solution may be discharged from the dissolution tank 1. In this case, the production equipment AA does not need to have the starting liquid tank 2. [Explanation of symbols]

[0073] 1 Dissolution tank 10 Tank body 12 Charging port 13 Lid 15 Screen board 16 Liquid supply port 17 Overflow port 18 Drainage port 19 Exit 20 Return port 21 Injection part 51 Small circulation canal 52 Chlorine gas supply pipe

Claims

1. A tank body, a drain plate provided inside the tank body and on which the nickel raw material is placed; an injection unit that sprays a liquid onto the nickel raw material; a chlorine gas supply pipe for supplying chlorine gas into the tank body; a drain outlet provided below the drain board and for discharging the produced nickel chloride aqueous solution by overflow. A dissolution tank characterized by:

2. A small circulation pipe is provided to extract the nickel chloride aqueous solution from the bottom of the tank body and circulate it to the injection section.

2. The dissolution tank according to claim 1.

3. The drainboard is provided to divide the tank body into upper and lower sections.

2. The dissolution tank according to claim 1.

4. a top plate having an inlet for charging the nickel raw material; the injection section is made up of a small annular pipe and a large annular pipe concentrically arranged, and is provided on the lower surface of the top plate; The inlet is disposed inside the small annular pipe.

2. The dissolution tank according to claim 1.

5. A heat exchanger is provided in the small circulation pipe to cool the nickel chloride aqueous solution.

3. The dissolution tank according to claim 2.

6. By spraying the liquid onto the nickel raw material in a chlorine gas atmosphere, the nickel raw material is chlorine-leached to produce an aqueous nickel chloride solution.

1. A method for producing an aqueous nickel chloride solution comprising the steps of:

7. The nickel raw material is electrolytic nickel 7. The method for producing an aqueous nickel chloride solution according to claim 6.

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