Method for producing nickel chloride aqueous solution

Abstract

To provide a method for producing an aqueous solution of nickel chloride capable of maintaining a high dissolution efficiency.SOLUTION: There is provided a method for producing an aqueous solution of nickel chloride which comprises: a raw material charging step of charging a nickel raw material N in a dissolution tank 1 having airtightness; a liquid supply step of supplying a dissolution starting liquid to the dissolution tank 1; a chlorine gas supply step of supplying chlorine gas to the dissolution tank 1; and a raw material recharging step of charging a new nickel raw material N in the dissolution tank 1 when the amount of the nickel raw material N in the dissolver 1 has decreased to the specified amount. Since the new nickel raw material N is charged at the timing when the amount of the nickel raw material N is reduced, the dissolution of the nickel raw material N can be maintained at high efficiency.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for producing an aqueous nickel chloride solution. More specifically, the present invention relates to a method for producing an aqueous nickel chloride solution by chlorine leaching of a nickel raw material.

Background Art

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

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] One method for obtaining an aqueous nickel chloride solution is to chlorine leaching of nickel raw materials. In this method, the amount of nickel raw materials in the dissolution tank decreases as the chlorine leaching reaction progresses. As the amount of nickel raw materials decreases, the contact area with the aqueous nickel chloride solution decreases, and the dissolution rate slows down. Therefore, it is preferable to end the batch process while a certain amount of nickel raw materials remain in the dissolution tank before they are completely consumed, and to recharge the nickel raw materials. However, since the dissolution tank is sealed during batch processing, it is difficult to visually check the remaining amount of nickel raw materials.

[0006] In view of the above circumstances, the present invention The timing for charging nickel raw materials can be easily determined. aims to provide a method for producing an aqueous nickel chloride solution.

Means for Solving the Problems

[0007] The first invention is a method for producing an aqueous nickel chloride solution by chlorine leaching of a nickel raw material, comprising: a raw material charging step of charging the nickel raw material into an airtight dissolution tank; a liquid supply step of supplying a dissolution starter to the dissolution tank; a chlorine gas supply step of supplying chlorine gas to the dissolution tank; and a raw material recharging step of charging new nickel raw material into the dissolution tank when the amount of nickel raw material in the dissolution tank has decreased to a specified amount. In the raw material recharging process, when the cumulative supply amount of chlorine gas reaches a standard value, it is determined that the nickel raw material has decreased to the specified amount. It is characterized by the following: 2nd The invention provides a method for producing an aqueous nickel chloride solution. A method for producing an aqueous nickel chloride solution by chlorine leaching of a nickel raw material, comprising: a raw material charging step of charging the nickel raw material into an airtight dissolution tank; a liquid supply step of supplying a dissolution starter to the dissolution tank; a chlorine gas supply step of supplying chlorine gas to the dissolution tank; and a raw material recharging step of charging new nickel raw material into the dissolution tank when the amount of nickel raw material in the dissolution tank has decreased to a specified amount, In the chlorine gas supply step, an amount of chlorine gas is supplied to the dissolution tank such that the pressure in the gas phase of the dissolution tank becomes constant, and in the raw material recharging step, when the amount of chlorine gas supplied falls to a standard value, it is determined that the nickel raw material has decreased to the specified amount. Third The method for producing an aqueous nickel chloride solution of the invention is the first or the second invention In the raw material recharging process, the nickel raw material is charged after the chlorine gas in the dissolution tank has been degassed. 4th The invention's method for producing an aqueous nickel chloride solution is as follows: Third In any of the inventions, the nickel raw material is chlorinated in a plurality of dissolution tanks while staggering the timing of charging the nickel raw material to obtain the nickel chloride aqueous solution. Fifth The invention's method for producing an aqueous nickel chloride solution is as follows: 4th In any of the inventions, the nickel raw material is characterized in that it is electrolytic nickel. [Effects of the Invention]

[0008] 1 According to the invention, the timing for charging nickel raw materials can be easily determined by using the cumulative supply amount of chlorine gas as an indicator. 2ndAccording to the invention, by using the supply amount of chlorine gas as an index, the timing of charging the nickel raw material can be easily determined. Third According to the invention, since the chlorine gas in the dissolution tank is degassed, the operation of charging the nickel raw material can be performed safely. 4th According to the invention, by operating a plurality of dissolution tanks while shifting the timing of charging the nickel raw material, an aqueous nickel chloride solution can be continuously produced. Also, the production rate of the aqueous nickel chloride solution can be leveled. Fifth According to the invention, a high-purity aqueous nickel chloride solution can be obtained.

Brief Description of the Drawings

[0009] [Figure 1] It is an overall configuration diagram of the manufacturing equipment according to the first embodiment. [Figure 2] It is a longitudinal sectional view of the dissolution tank. [Figure 3] It is a longitudinal sectional view of the starting liquid tank. [Figure 4] It is an explanatory diagram showing the state of the dissolution tank in the (1) raw material charging step and the (2) liquid supply step. [Figure 5] It is an explanatory diagram showing the state of the dissolution tank in the (3) decompression step and the (4) chlorine gas supply step. [Figure 6] It is an overall configuration diagram of the manufacturing equipment according to the second embodiment.

Modes for Carrying Out the Invention

[0010] Next, embodiments of the present invention will be described based on the drawings. 〔First Embodiment〕 The method for producing an aqueous nickel chloride solution according to the first embodiment of the present invention is a method 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 without performing special purification treatment.

[0011] Electrolytic nickel can be produced, for example, by the wet smelting of nickel. In the wet smelting of nickel, raw materials such as nickel matte and nickel-cobalt mixed sulfide are leached with chlorine. A purification treatment is performed to remove impurities from the leachate, and an aqueous nickel chloride solution is obtained. Electrolytic nickel is obtained by electrolytic extraction using the aqueous nickel chloride solution as an electrolyte.

[0012] In order to increase the dissolution efficiency, it is preferable that the electrolytic nickel is smaller. For example, it is preferable to use electrolytic nickel in the form of a plate cut to a size of 100 mm × 100 mm or less. Also, button-shaped electrolytic nickel may be used. The smaller the size of the electrolytic nickel, the larger the contact area with the aqueous nickel chloride solution, so that chlorine leaching proceeds efficiently.

[0013] (Manufacturing Equipment) The manufacturing method of this embodiment uses the manufacturing equipment AA shown in FIG. 1. The manufacturing equipment AA has a dissolution tank 1, a starting solution tank 2, an adjustment tank 3, and a final solution tank 4. Also, the manufacturing equipment AA has a control device 5 that acquires measurement values from various measuring instruments and controls the operations of various valves, pumps, etc. A computer such as a PLC can be used as the control device 5.

[0014] As shown in FIG. 2, the dissolution tank 1 is a tank for leaching nickel raw material N with chlorine. The dissolution tank 1 has a tank body 10. The tank body 10 is a tank having airtightness. The shape of the tank body 10 is not particularly limited and may be cylindrical or rectangular.

[0015] An inlet 12 is provided at the center of the top plate of the tank body 10. The nickel raw material N is charged into the inside of the tank body 10 through the inlet 12. The inlet 12 is closed by a lid 13. Also, a water seal portion for water-sealing between the inlet 12 and the lid 13 is provided. Therefore, by closing the inlet 12 with the lid 13 and water-sealing, the tank body 10 can be made airtight.

[0016] A slatted plate 15 is provided inside the tank body 10. The slatted plate 15 is installed horizontally so as to cross the tank body 10 near the center of the top and bottom. The internal space of the tank body 10 is divided into two spaces, upper and lower, by the slatted plate 15. As the slatted plate 15, a plate material having multiple holes or slits, such as a perforated plate or a wedge wire screen, is used. The nickel raw material N charged in from the charging port 12 is placed on the slatted plate 15. Meanwhile, the liquid passes through the slatted plate 15 and flows down from the upper space to the lower space of the tank body 10.

[0017] A liquid inlet 16 is provided on the top plate of the tank body 10. The liquid inlet 16 is connected to a liquid supply device. The initial dissolving solution supplied from the liquid supply device flows into the tank body 10 through the liquid inlet 16. Details of the liquid supply device will be described 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 slat plate 15 and close to the top of the tank body 10. On the other hand, the drain port 18 is located below the slat plate 15 and close to the slat plate 15. Both the overflow port 17 and the drain port 18 are used to drain the liquid from inside the tank body 10.

[0019] An outlet 19 is provided on the side wall of the tank body 10. The outlet 19 is located below the drain port 18 and close to 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 installed 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 drawn out from the bottom of the tank body 10 and 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 withdrawn from the tank body 10 is cooled and then returned to the tank body 10.

[0022] Inside the tank body 10, an injection unit 21 is provided near the underside of the top plate. The return port 20 is connected to the injection unit 21. The liquid that has circulated through the small circulation pipe 51 is injected from the injection unit 21, wetting the nickel raw material N.

[0023] The injection unit 21 consists of a small annular tube 21a and a large annular tube 21b arranged concentrically. Each of the small annular tube 21a and the large annular tube 21b has multiple holes provided at predetermined intervals, and liquid is injected from these holes. The charging port 12 is located inside the small annular tube 21a. Therefore, the injection unit 21 does not get in the way when charging nickel raw material N.

[0024] A chlorine gas supply pipe 52 is connected to the tank body 10. The open end of the chlorine gas supply pipe 52 is inside the tank body 10 and located below the slat plate 15. The other end of the chlorine gas supply pipe 52 is connected to a chlorine gas supply source 74. A gas cylinder containing 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 to the inside of the tank body 10 by the chlorine gas supply pipe 52. The amount of chlorine gas supplied can also be adjusted by adjusting the opening 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.

[0025] A pressure gauge 22 is provided on the top plate of the tank body 10. The pressure gauge 22 can measure the pressure in the gas phase inside the dissolution tank 1.

[0026] A ring collection port 23 is provided on the top plate of the tank body 10. A ring collection tube 53 is connected to the ring collection port 23. An exhaust valve 62 is also provided on the ring collection tube 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.

[0027] The gas phase within the dissolution tank 1 is filled with chlorine gas supplied from the chlorine gas supply pipe 52. The nickel raw material N is also moistened by the liquid sprayed from the spray unit 21. This results in the nickel raw material N being covered with a liquid film under 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 proceeds, generating an aqueous nickel chloride solution. In this way, the nickel raw material N is chlorinated within the dissolution tank 1 to produce an aqueous nickel chloride solution. The generated aqueous nickel chloride solution is temporarily stored at the bottom of the dissolution tank 1 and discharged from the drain port 18 or the outlet 19.

[0028] As shown in Figure 3, the initial liquid tank 2 is a tank for storing the initial dissolution liquid. The initial dissolution liquid is either an aqueous nickel chloride solution or water. Pure water is preferred as the initial dissolution liquid. This allows for the acquisition of a high-purity aqueous nickel chloride solution. The shape of the initial liquid tank 2 is not particularly limited and may be cylindrical or rectangular. Furthermore, the initial liquid tank 2 does not require the same airtightness as the dissolution tank 1. However, since chlorine gas is dissolved in the initial dissolution liquid during steady operation, it is preferable that the gas phase portion of the initial liquid tank 2 is also enclosed.

[0029] A liquid outlet 31 and a liquid inlet 32 ​​are provided at the bottom of the initial liquid tank 2. 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 a stirrer 35. The initial liquid solution can be stirred by driving the stirrer 35. The initial liquid tank 2 is equipped with a pH meter 36. The pH of the initial liquid solution can be measured using the pH meter 36. The initial liquid tank 2 is equipped with a liquid level gauge 37. The liquid level in the initial liquid tank 2 can be measured using the liquid level gauge 37.

[0030] As shown in Figure 1, one end of a supply pipe 54 is connected to the liquid outlet 31 of the initial liquid tank 2. The other end of the supply pipe 54 is connected to the liquid inlet 16 of the dissolution tank 1. A supply pump 72 is provided on the supply pipe 54. When the supply pump 72 is driven, the initial dissolution liquid in the initial liquid tank 2 is supplied to the dissolution tank 1. Therefore, the initial liquid tank 2, the supply pipe 54, and the supply pump 72 constitute a liquid supply device that supplies the initial dissolution liquid to the dissolution tank 1.

[0031] One end of a drain pipe 55 is connected to the liquid inlet 32 ​​of the initial liquid tank 2. The other end of the drain pipe 55 is connected to the drain port 18 of the dissolution tank 1. A drain valve 63 is provided in the drain pipe 55. Therefore, when the drain valve 63 is opened, the nickel chloride aqueous solution produced in the dissolution tank 1 is discharged to the initial liquid tank 2 via the drain pipe 55. The supply pipe 54 and the drain pipe 55 constitute a large circulation channel that circulates the liquid between the initial liquid tank 2 and the dissolution tank 1.

[0032] 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 (starting tank 2 side) of the drain valve 63 of the drain pipe 55. The liquid that overflows from the overflow port 17 of the dissolution tank 1 is discharged to the starting tank 2 via the overflow pipe 56 and the drain pipe 55.

[0033] As shown in Figure 3, a water addition device is provided in the initial liquid tank 2. The water addition device includes a water supply source 75, a water supply pipe 57, and a flow control valve 64. A water storage tank, utility piping within the factory, etc., can be used as the water supply source 75. The water supply pipe 57 connects the water supply source 75 to the water addition port 33 of the initial 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 initial liquid tank 2.

[0034] By adding water to the initial tank 2 using the water addition device, water can be added to the nickel chloride aqueous solution that has returned to the initial tank 2 from the dissolution tank 1. The concentration of the nickel chloride aqueous solution can be adjusted by adding water. Here, stirring with the agitator 35 can make the concentration of the nickel chloride aqueous solution in the initial tank 2 uniform. Furthermore, if pure water is used as the water to be added, the contamination of the nickel chloride aqueous solution with impurities can be prevented.

[0035] A hydrochloric acid addition device is provided in the initial liquid tank 2. The hydrochloric acid addition device includes a hydrochloric acid supply source 76, a hydrochloric acid supply pipe 58, and a flow control valve 65. A tank for storing hydrochloric acid, utility piping within the factory, etc., 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 initial 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 initial liquid tank 2.

[0036] By adding hydrochloric acid to the initial tank 2 using the hydrochloric acid addition device, hydrochloric acid can be added to the nickel chloride aqueous solution that has returned to the initial tank 2 from the dissolution tank 1. The pH of the nickel chloride aqueous solution can be adjusted by adding hydrochloric acid. Here, stirring with the stirrer 35 can make the pH of the nickel chloride aqueous solution in the initial tank 2 uniform. In addition, the pH of the nickel chloride aqueous solution can be measured with the pH meter 36.

[0037] As shown in Figure 1, the manufacturing equipment AA has a drainage device for discharging the generated nickel chloride aqueous solution. The drainage device has a discharge pipe 59 and a flow control valve 66. One end of the discharge pipe 59 is connected to the downstream side (dissolution tank 1 side) of the supply pipe 54 from the supply pump 72. The other end of the discharge pipe 59 is connected to the final liquid tank 4. The flow control valve 66 is provided on the discharge pipe 59. When the flow control valve 66 is opened, a portion of the nickel chloride aqueous solution flowing through the supply pipe 54 flows through the discharge pipe 59 and is guided to the final liquid tank 4.

[0038] A conditioning tank 3 is provided in the middle of the discharge pipe 59. The conditioning tank 3 is filled with nickel raw material. Chlorine gas is dissolved in the nickel chloride aqueous solution produced in the dissolution tank 1. When this nickel chloride aqueous solution is passed through the conditioning tank 3, the nickel raw material in the conditioning tank 3 is leached out by the chlorine gas dissolved in the nickel chloride aqueous solution. As the chlorine gas dissolved in the nickel chloride aqueous solution is consumed in the leaching of the nickel raw material, the chlorine gas can be removed from the nickel chloride aqueous solution. In this way, the contamination of the nickel chloride aqueous solution with impurities can be suppressed compared to cases where dissolved chlorine gas is removed using chemicals such as reducing agents. It is preferable to use electrolytic nickel as the nickel raw material to fill the conditioning tank 3. Since electrolytic nickel is high-purity nickel, the contamination of the nickel chloride aqueous solution with impurities can be further suppressed. The nickel chloride aqueous solution that has passed through the conditioning tank 3 is stored in the final liquid tank 4.

[0039] (Manufacturing method) Next, the method for producing the nickel chloride aqueous solution according to this embodiment will be described.

[0040] (1) Raw material charging process In dissolution tank 1, nickel raw material N is leached with chlorine in a batch process to produce an aqueous nickel chloride solution. As shown in Figure 4 (1), at the start of the batch process, the lid 13 of dissolution tank 1 is removed and nickel raw material N is charged in through the charging port 12. The nickel raw material N is piled up on the bamboo mat 15. After the nickel raw material N is charged in, the charging port 12 is closed with the lid 13. Then, a water seal is created between the charging port 12 and the lid 13.

[0041] (2) Liquid supply process Next, as shown in (2) of Figure 4, the exhaust valve 62 of the ring collection tube 53 is opened. The liquid supply pump 72 is driven to supply the initial dissolution solution in the initial liquid tank 2 to the dissolution tank 1 (see Figure 1). Note that when the manufacturing equipment AA is started for the first time, or when there is no residual nickel chloride aqueous solution, the initial dissolution solution in the initial liquid tank 2 is water, preferably pure water. During steady operation in which batch processing is repeated, the initial dissolution solution in the initial liquid tank 2 is the nickel chloride aqueous solution produced in the previous batch processing.

[0042] The initial dissolution solution is supplied to the dissolution tank 1 from the supply port 16. As the initial dissolution solution is supplied, the liquid level in the dissolution tank 1 gradually rises. Consequently, the air in the gas phase of the dissolution tank 1 is exhausted from the collection tube 53. When the liquid level in the dissolution tank 1 reaches the height of the overflow port 17, the initial dissolution solution is discharged from the overflow port 17. At this point, most of the air present in the dissolution tank 1 is exhausted. The initial dissolution solution discharged from the overflow port 17 is returned to the initial liquid tank 2 via the overflow pipe 56 and the drain pipe 55 (see Figure 1). The supply of the initial dissolution solution from the supply port 16 continues until the batch processing is completed.

[0043] Furthermore, a small circulation pump 71 is driven to extract liquid from the outlet 19 and inject it from the injection unit 21. This liquid circulation continues until the batch processing is completed.

[0044] (3) Depressurization process Next, as shown in (3) of Figure 5, the exhaust valve 62 of the ring collection tube 53 is closed to seal the dissolution tank 1. Then, the drain valve 63 is opened to return the initial dissolution liquid in the dissolution tank 1 to the starting liquid tank 2 via the drain pipe 55 (see Figure 1). When the drain valve 63 of the drain pipe 55 is opened, the initial dissolution 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 decreases. Since the dissolution tank 1 is sealed, the pressure in the gas phase gradually decreases as the liquid level decreases, resulting in negative pressure. In this way, after filling the dissolution tank 1 with the initial dissolution liquid, the dissolution tank 1 is sealed to lower the liquid level of the initial dissolution liquid, thereby creating negative pressure inside the dissolution tank 1.

[0045] (4) Chlorine gas supply process Simultaneously with opening the drain valve 63 of the drain pipe 55, or immediately thereafter, the supply of chlorine gas to the dissolution tank 1 is started. As shown in Figure 5 (4), the supply of chlorine gas is performed by opening the flow control valve 61 of the chlorine gas supply pipe 52. As the liquid level in the dissolution tank 1 decreases, the supply of chlorine gas creates a chlorine gas atmosphere in the gas phase of the dissolution tank 1. The supply of chlorine gas continues until the batch processing is completed.

[0046] Here, it is preferable to control the amount of chlorine gas supplied so that the pressure in the gas phase of the dissolution tank 1 remains constant at a predetermined pressure. The pressure in the gas phase of the dissolution tank 1 can be measured by a pressure gauge 22. The control device 5 obtains the measured value from the pressure gauge 22 and controls the opening of the flow control valve 61 so that the measured value remains constant at a predetermined pressure, thereby adjusting the amount of chlorine gas supplied. For example, the control device 5 performs feedback control with the pressure in the gas phase of the dissolution tank 1 as the controlled variable and the amount of chlorine gas supplied as the manipulated variable. The target value of the pressure in the gas phase of the dissolution tank 1 is set to, for example, between -1 and -3 kPa.

[0047] The liquid level in the dissolution tank 1 drops to the height of the drain port 18 and remains constant at this level. At this time, the position of the open end of the chlorine gas supply pipe 52 (the chlorine gas discharge port) may be higher than the liquid level, at the same level as the liquid level, or lower than the liquid level. In other words, the chlorine gas may be supplied directly to the gas phase in the dissolution tank 1, or it may be supplied into the liquid in the dissolution tank 1.

[0048] (5) Leaching process When the supply of chlorine gas is started, the chlorine leaching reaction of nickel raw material N begins. The gas phase in the dissolution tank 1 is filled with chlorine gas. In addition, the nickel raw material N is moistened by the liquid sprayed from the spray unit 21. As a result, the nickel raw material N is covered with a liquid film under 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 proceeds, and an aqueous nickel chloride solution is produced. The produced aqueous nickel chloride solution is temporarily stored at the bottom 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 initial liquid tank 2 via the large circulation channels 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.

[0049] The chlorine leaching reaction of nickel raw material N consumes chlorine gas, causing a decrease in the pressure of the gas phase in the dissolution tank 1. However, when the supply of chlorine gas is controlled based on the pressure of the gas phase in the dissolution tank 1, an amount of chlorine gas is supplied that maintains a constant pressure in the gas phase of the dissolution tank 1. In other words, the amount of chlorine gas consumed in the chlorine leaching reaction is newly supplied.

[0050] (6) Temperature adjustment process The chlorine leaching reaction of 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 2, 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 suitable temperature, for example, 50-60°C, from the perspective of protecting the equipment. This suppresses the temperature rise due to the heat of reaction and protects the equipment.

[0051] (7) Water addition process In the dissolution tank 1, the chlorine leaching reaction of nickel raw material N proceeds continuously. As a result, the nickel concentration in the nickel chloride aqueous solution gradually increases. Therefore, it is preferable to adjust the nickel concentration of the nickel chloride aqueous solution by adding water, preferably pure water.

[0052] In this embodiment, as shown in Figure 3, water is added to the initial tank 2. This adds water to the nickel chloride aqueous solution that has returned to the initial tank 2 from the dissolution tank 1. Here, it is preferable that the control device 5 adjusts the amount of water added to the nickel chloride aqueous solution to an amount determined based on the amount of chlorine gas supplied to the dissolution tank 1.

[0053] The ratio of the amount of chlorine gas consumed in the chlorine leaching reaction to the amount of nickel leached out is known. Therefore, the amount of water added should be 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 opening of the flow control valve 64 of the water supply pipe 57 so that the amount of water added reaches that target value.

[0054] The nickel concentration in the nickel chloride solution is adjusted to the desired concentration by adding water. For example, the nickel concentration of the nickel chloride solution is adjusted to a predetermined value between 130 and 160 g / L. Alternatively, the nickel concentration of the nickel chloride solution may be measured periodically using a hydrometer or similar device, and the coefficient multiplied by the chlorine gas supply amount to determine the amount of water to be added may be adjusted as needed.

[0055] (8) pH adjustment process It is preferable to adjust the pH of the nickel chloride aqueous solution by adding hydrochloric acid. In this embodiment, as shown in Figure 3, hydrochloric acid is added to the initial tank 2. Here, it is preferable to adjust the pH of the nickel chloride aqueous solution to 1 to 3. The pH of the nickel chloride aqueous solution in the initial tank 2 can be measured by a pH meter 36. The control device 5 obtains the measurement value from the pH meter 36 and controls the opening of the flow control valve 65 of the hydrochloric acid supply pipe 58 so that the measurement value becomes a predetermined target value, thereby adjusting the amount of hydrochloric acid supplied. For example, the control device 5 performs feedback control with the pH of the nickel chloride aqueous solution as the controlled variable and the amount of hydrochloric acid supplied as the manipulated variable.

[0056] Maintaining the pH of the nickel chloride aqueous solution between 1 and 3 prevents the oxidation-neutralization reaction from occurring. Therefore, the formation of hydroxides and oxides through this oxidation-neutralization reaction can be suppressed.

[0057] (9) Drainage process The addition of water and hydrochloric acid causes the liquid level in the initial tank 2 to rise. The initial tank 2 then contains a nickel chloride aqueous solution with adjusted nickel concentration and pH. This adjusted nickel chloride aqueous solution is then discharged from the initial tank 2. The discharge of the nickel chloride aqueous solution is carried out by a drainage device.

[0058] As shown in Figure 1, the drainage system has a discharge pipe 59 and a flow control valve 66. Prepared nickel chloride aqueous solution flows through the supply pipe 54. By opening the flow control valve 66, a portion of the nickel chloride aqueous solution flowing through the supply pipe 54 is diverted to the discharge pipe 59 and guided to the final liquid tank 4.

[0059] Here, it is preferable for the control device 5 to adjust the discharge rate of the nickel chloride aqueous solution so that the liquid level in the initial tank 2 remains constant. Specifically, the liquid level in the initial tank 2 can be measured by the liquid level gauge 37. The control device 5 obtains the measured value from the liquid level gauge 37 and controls the opening of the flow control valve 66 of the discharge pipe 59 so that the measured value remains constant at a predetermined value, thereby adjusting the discharge rate of the nickel chloride aqueous solution. For example, the control device 5 performs feedback control with the liquid level in the initial tank 2 as the controlled amount and the discharge rate of the nickel chloride aqueous solution as the manipulated amount. By performing such control, the generated amount of nickel chloride aqueous solution can be discharged.

[0060] (10) Dechlorination gas process The nickel chloride aqueous solution discharged from the initial tank 2 is supplied to the adjustment tank 3. The adjustment tank 3 is filled with nickel raw material. Chlorine gas is dissolved in the nickel chloride aqueous solution produced in the dissolution tank 1. When this nickel chloride aqueous solution is passed through the adjustment tank 3, the nickel chloride aqueous solution and the nickel raw material come into contact, and the nickel raw material is leached out by the chlorine gas dissolved in the nickel chloride aqueous solution. The chlorine gas dissolved in the nickel chloride aqueous solution is consumed in the leaching of the nickel raw material, thus removing the chlorine gas from the nickel chloride aqueous solution. The nickel chloride aqueous solution, from which the dissolved chlorine gas has been removed after passing through the adjustment tank 3, is stored in the final tank 4.

[0061] Furthermore, each process from (4) the chlorine gas supply process to (10) the dechlorination gas process is carried out simultaneously. That is, as the chlorine leaching reaction of the nickel raw material N progresses, the generated nickel chloride aqueous solution is adjusted, and the amount of nickel chloride aqueous solution generated is discharged.

[0062] (11) Raw material recharging process As the chlorine leaching reaction progresses, the amount of nickel raw material N in the dissolution tank 1 decreases. As the amount of nickel raw material N decreases, the contact area with the nickel chloride aqueous solution decreases, and the dissolution rate decreases. Therefore, it is preferable to end the batch process while a certain amount of nickel raw material N remains in the dissolution tank 1 before it is completely consumed, and to recharge the nickel raw material N. By doing so, the dissolution rate of nickel raw material N can be maintained at a high level, and the production rate of nickel chloride aqueous solution per unit time can be improved. On the other hand, recharging the nickel raw material N requires the operation of discharging the residual gas in the dissolution tank 1 and recharging the nickel raw material N, which results in downtime for the equipment. If a large amount of nickel raw material N remains in order to maintain a high dissolution rate, the frequency of recharging will increase. In that case, the downtime of the equipment will increase, and the equipment operating rate will decrease.

[0063] Therefore, when the amount of nickel raw material N in dissolution tank 1 decreases to a specified amount, new nickel raw material N is added to dissolution tank 1. Here, "specified amount" is an indicator that determines the timing of re-adding nickel raw material N, and means a predetermined amount of residual nickel raw material N. It is preferable to set the specified amount so as to maximize the production efficiency of the nickel chloride aqueous solution, taking into account the balance between the dissolution rate of nickel raw material N and the equipment operating time rate. In this way, by adding new nickel raw material N when the amount of nickel raw material N decreases, the leaching reaction of nickel raw material N, i.e., the dissolution of nickel raw material N, can be maintained at a high efficiency.

[0064] The batch process is terminated when the amount of nickel raw material N decreases to a specified level. Here, the amount of nickel charged into the dissolution tank 1 at the start of the batch process can be determined from the amount of nickel raw material N charged. Also, the amount of nickel consumed in the chlorine leaching reaction can be determined from the amount of chlorine gas consumed. Therefore, the remaining amount of nickel raw material N can be estimated from the total amount of chlorine gas supplied to the dissolution tank 1 from the start of the batch process (cumulative supply amount). Thus, when the cumulative supply amount of chlorine gas reaches a standard value, it can be determined that the amount of nickel raw material N has decreased to a specified level. Here, the standard value is determined as the cumulative supply amount of chlorine gas when a predetermined percentage (for example, 40%) of the amount of nickel charged into the dissolution tank 1 at the start of the batch process is consumed.

[0065] When the amount of nickel raw material N in dissolution tank 1 decreases, the contact area between the nickel raw material N and the nickel chloride aqueous solution decreases. In other words, the area of ​​the solid-liquid interface involved in the chlorine leaching reaction decreases. As a result, the chlorine leaching reaction proceeds less easily, and the amount of chlorine gas consumed also decreases. When the amount of chlorine gas supplied is controlled based on the pressure in the gas phase of dissolution tank 1, the amount of chlorine gas consumed can be determined from the amount of chlorine gas supplied. Therefore, when the amount of chlorine gas supplied falls to a standard value, it may be determined that the amount of nickel raw material N has decreased to a specified amount.

[0066] Since dissolution tank 1 is sealed during batch processing, it is difficult to visually confirm the remaining amount of nickel raw material N. However, as described above, the timing for charging nickel raw material N can be easily determined by using the cumulative supply amount of chlorine gas or the supply amount of chlorine gas as an indicator.

[0067] When the amount of nickel raw material N decreases to a specified level, the batch process is terminated and new nickel raw material N is added to the dissolution tank 1. 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 circulating pipe 53 is opened to degas the chlorine gas in the dissolution tank 1. The chlorine gas discharged from the circulating pipe 53 is led to the pollution tower where pollution treatment is performed. In addition, 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 initial dissolution solution from the liquid supply pipe 54 to the dissolution tank 1 is stopped.

[0068] After a certain period of time has elapsed since opening the exhaust valve 62 of the ring collection tube 53, degassing is completed. Then, the lid 13 of the dissolution tank 1 is removed and new nickel raw material N is charged in through the charging port 12. Since the chlorine gas in the dissolution tank 1 is degassed, the charging of nickel raw material N can be carried out safely. From there, a new batch process is carried out. That is, each process from (2) the liquid supply process to (10) the dechlorination gas process is repeated.

[0069] [Second Embodiment] Next, a method for producing an aqueous nickel chloride solution according to the second embodiment of the present invention will be described.

[0070] (manufacturing equipment) The manufacturing method of this embodiment uses the manufacturing equipment BB shown in Figure 6. Manufacturing equipment BB has multiple (three in the illustrated example) dissolution tanks 1A, 1B, and 1C. The number of dissolution tanks 1A, 1B, and 1C is not particularly limited and may be two or four or more. The configuration of each dissolution tank 1A, 1B, and 1C is the same as that of dissolution tank 1 in the first embodiment.

[0071] Manufacturing equipment BB has one initial liquid tank 2. The configuration of the initial liquid tank 2 is the same as in the first embodiment. Multiple dissolution tanks 1A, 1B, and 1C are each connected to the initial liquid tank 2 by a large circulation channel. In other words, manufacturing equipment BB has multiple large circulation channels (the same number as dissolution tanks 1A, 1B, and 1C).

[0072] Specifically, the liquid supply pipe 54 branches into several branch pipes 54A, 54B, and 54C along the way. Each of these branch pipes 54A, 54B, and 54C is connected to the liquid supply port 16 of the corresponding dissolution tanks 1A, 1B, and 1C. In addition, each of the branch pipes 54A, 54B, and 54C is equipped with flow control valves 67A, 67B, and 67C. The flow rate of the initial dissolution liquid supplied to the dissolution tanks 1A, 1B, and 1C can be adjusted by controlling the opening of the flow control valves 67A, 67B, and 67C.

[0073] One end of each drain pipe 55A, 55B, and 55C is connected to the drain port 18 of each dissolution tank 1A, 1B, and 1C. The other ends of each drain pipe 55A, 55B, and 55C are all connected to the liquid inlet 32 ​​of the starting tank 2. In addition, one end of each overflow pipe 56A, 56B, and 56C is connected to the overflow port 17 of each dissolution tank 1A, 1B, and 1C. The other ends of each overflow pipe 56A, 56B, and 56C are connected to the corresponding drain pipes 55A, 55B, and 55C.

[0074] The liquid circulates between dissolution tanks 1A, 1B, and 1C and the initial liquid tank 2 via the large circulation channel described above.

[0075] A discharge pipe 59 is connected to the supply pipe 54. When the flow control valve 66 is opened, a portion of the nickel chloride aqueous solution flowing through the supply pipe 54 flows through the discharge pipe 59 and is led to the final liquid tank 4.

[0076] (Manufacturing method) Next, the method for producing the nickel chloride aqueous solution according to this embodiment will be described. Dissolution tanks 1A, 1B, and 1C each perform batch processing in the same procedure as in the first embodiment. That is, they perform steps (1) from the raw material charging step to (10) the dechlorination gas step, and when the amount of nickel raw material N decreases, they charge more nickel raw material N. Here, no nickel chloride aqueous solution is generated between steps (1) from the raw material charging step to (3) the reduced pressure step and in step (11) the raw material recharging step. These steps can be considered preparation steps between batch processing.

[0077] Therefore, batch processing is performed in multiple dissolution tanks 1A, 1B, and 1C while staggering the timing of charging the nickel raw material N. As a result, nickel chloride aqueous solution will be produced in one of the dissolution tanks 1A, 1B, or 1C during the operating period of the manufacturing facility BB. In other words, by operating multiple dissolution tanks 1A, 1B, and 1C while staggering the timing of charging the nickel raw material N, nickel chloride aqueous solution can be produced continuously. Furthermore, the production rate of nickel chloride aqueous solution can be leveled.

[0078] Since the initial liquid tank 2 and the adjustment tank 3 are common to dissolution tanks 1A, 1B, and 1C, each step from (7) water addition to (10) dechlorination gas step is carried out in common.

[0079] [Other Embodiments] In the embodiment described above, the nickel chloride aqueous solution in the dissolution tank 1 is circulated through the small circulation pipe 51 and injected from the injection unit 21 onto the nickel raw material N. Alternatively, the nickel chloride aqueous solution circulating in the large circulation channel between the dissolution tank 1 and the initial liquid tank 2 may be injected from the injection unit 21. In this case, the small circulation pipe 51 may be omitted. Furthermore, the temperature of the nickel chloride aqueous solution may be controlled by a heat exchanger provided in the large circulation channel.

[0080] In the above embodiment, the dissolution tank 1 undergoes chlorine leaching under negative pressure, but it may also undergo chlorine leaching under positive pressure. In either case, the dissolution tank 1 is kept airtight. Chlorine gas is not discharged from the dissolution tank 1 while the chlorine leaching reaction is progressing. Therefore, a large-scale chlorine gas abatement device is unnecessary.

[0081] The nickel concentration of the nickel chloride aqueous solution may be adjusted by adding water to dissolution tank 1. Alternatively, the pH of the nickel chloride aqueous solution may be adjusted by adding hydrochloric acid to dissolution tank 1. In other words, the nickel chloride aqueous solution may be adjusted in dissolution tank 1, and the adjusted nickel chloride aqueous solution may be discharged from dissolution tank 1. In this case, the initial tank 2 may be omitted. [Explanation of Symbols]

[0082] AA, BB manufacturing equipment 1 Dissolution tank 12 Charging port 15 Screen board 2 Starting liquid tank 3 Adjustment tank 4. Final liquid tank 5 Control device 52 Chlorine gas supply pipe 54 Liquid supply pipe 55 Drainage pipe 56 Overflow pipe

Claims

1. A method for producing an aqueous nickel chloride solution by chlorine leaching a nickel raw material, A raw material charging step involves charging the nickel raw material into an airtight melting tank, A liquid supply step of supplying the initial dissolution solution to the dissolution tank, A chlorine gas supply step of supplying chlorine gas to the dissolution tank, The system includes a raw material reloading step, in which new nickel raw material is loaded into the dissolution tank when the amount of nickel raw material in the dissolution tank has decreased to a specified amount. In the raw material recharging process, when the cumulative supply amount of chlorine gas reaches a standard value, it is determined that the nickel raw material has decreased to the specified amount. A method for producing an aqueous nickel chloride solution characterized by the above.

2. A method for producing an aqueous nickel chloride solution by chlorine leaching a nickel raw material, A raw material charging step involves charging the nickel raw material into an airtight melting tank, A liquid supply step of supplying the initial dissolution solution to the dissolution tank, A chlorine gas supply step of supplying chlorine gas to the dissolution tank, The system includes a raw material reloading step, in which new nickel raw material is loaded into the dissolution tank when the amount of nickel raw material in the dissolution tank has decreased to a specified amount. In the chlorine gas supply step, an amount of chlorine gas is supplied to the dissolution tank such that the pressure in the gas phase within the dissolution tank becomes constant. In the raw material recharging process, when the supply amount of chlorine gas decreases to a standard value, it is determined that the nickel raw material has decreased to the specified amount. A method for producing an aqueous nickel chloride solution characterized by the above.

3. In the raw material recharging process, after degassing the chlorine gas in the dissolution tank, the nickel raw material is charged. A method for producing an aqueous nickel chloride solution according to claim 1 or 2, characterized in that it.

4. The nickel raw material is chlorinated in multiple dissolution tanks while staggering the timing of charging the nickel raw material to obtain the nickel chloride aqueous solution. A method for producing an aqueous nickel chloride solution according to claim 1 or 2, characterized in that it.

5. The aforementioned nickel raw material is electrolytic nickel. A method for producing an aqueous nickel chloride solution according to claim 1 or 2, characterized in that it.

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