JP5920584B2 - Method of oxidation neutralization treatment of nickel chloride aqueous solution - Google Patents

Description

  The present invention relates to an oxidation neutralization treatment method for separating and removing cobalt and other impurities from an aqueous solution of nickel chloride, which is an intermediate for obtaining nickel and cobalt by hydrometallurgy.

In the smelting of nickel and cobalt, first, a nickel matte containing nickel or cobalt is obtained by dry smelting ore containing nickel or cobalt as a raw material.
The ores containing nickel and cobalt used in this raw material often contain impurity elements such as copper, iron, lead, manganese, and arsenic in addition to nickel and cobalt, and most of these impurity elements are contained in the nickel matte. Distributed.

The nickel mat is then crushed and mixed with a hydrochloric acid acidic solution to form a slurry.
A leaching solution containing nickel or cobalt is obtained by adding an oxidizing agent such as chlorine gas to the slurry, and a solution containing nickel and a solution containing cobalt are obtained from the obtained leaching solution using a means such as solvent extraction. Then, nickel or cobalt is obtained by electrowinning from a solution containing nickel or a solution containing cobalt.

  Furthermore, in recent years, sulfuric acid leaching of low-grade nickel oxide ore under high temperature and high pressure, and then sulfiding the obtained leachate to form a nickel-cobalt mixed sulfide enriched with nickel and cobalt, Similarly, a method of obtaining nickel or cobalt by leaching with chlorine gas and performing electrowinning is also used.

A specific method for obtaining nickel or cobalt by using this electrowinning will be described with reference to a flow chart of electrical nickel production in FIG.
First, in accordance with the flow shown in FIG. 1, nickel matte or nickel / cobalt mixed sulfide (hereinafter referred to as raw material) is leached to form a leachate.
Almost all of the impurities contained in these raw materials are leached into the solution (leachate), and when electrolytic extraction is performed from this solution, impurities in the solution will be mixed into the nickel and cobalt of the product. Prior to electrowinning, it is necessary to separate impurities and cobalt from the leachate.

In order to separate impurities from the leachate, first, copper is separated using a substitution reaction (cementation reaction). Next, iron and arsenic are separated by the oxidation neutralization treatment in the step of the previous oxidation neutralization treatment (oxidation neutralization 1) shown in FIG. After separation of iron and arsenic, an aqueous solution (nickel chloride solution: see FIG. 1) from which cobalt has been separated is obtained by solvent extraction.
The aqueous solution after the solvent extraction process in the separation process of impurities contains a trace amount of cobalt and lead, but a highly pure nickel chloride aqueous solution is obtained.

Furthermore, as a method for further separating a small amount of cobalt and lead from the obtained high-purity nickel chloride aqueous solution, the oxidizing agent and neutralization in the step of the subsequent oxidation neutralization treatment (oxidation neutralization 2) shown in FIG. An oxidative neutralization treatment is used in which an agent is added to oxidize cobalt or lead to trivalent ions and precipitate as hydroxides.
By this oxidative neutralization 2, a trace amount of cobalt and lead are separated, and an aqueous nickel chloride solution capable of electrolytically collecting nickel can be obtained.

Here, since the impurities in the nickel chloride aqueous solution are very small, the generated starch of hydroxide is a starch mainly composed of nickel hydroxide containing a small amount of cobalt hydroxide. Since the main component of this starch is nickel hydroxide, the starch can be dispensed into the nickel sulfate production process.
In the nickel sulfate production process, the starch is dissolved with sulfuric acid to form an aqueous nickel sulfate solution. Furthermore, impurities can be separated from the obtained nickel sulfate aqueous solution to produce nickel sulfate as a product.

Thus, since this starch is also a raw material of nickel sulfate, it is required that the amount of generated starch is small. Therefore, it is necessary to control the reaction system of the oxidative neutralization treatment so that impurities are precipitated and separated in the subsequent oxidative neutralization treatment (oxidation neutralization 2) step, and fluctuations in the amount of starch generated are reduced. .
Therefore, as a method for precipitating and separating impurities from an aqueous nickel chloride solution and controlling the reaction system so that fluctuations in the amount of starch generated are reduced, for example, the ratio of chlorine gas blowing to the amount of processing liquid is fixed, The flow rate is automatically controlled. On the other hand, the neutralizing agent, nickel carbonate, separates impurities and removes starch by a method of automatically adding nickel chloride aqueous solution so that the pH of the aqueous solution of nickel chloride matches the set value (see FIG. 2). Control is made so that fluctuations in the amount generated are reduced.
FIG. 2 is a schematic diagram for explaining a method for adding an oxidizing agent and a neutralizing agent in an oxidative neutralization process using conventional pH as an index for control. 2 is a reaction tank, 3 is an ORP meter, and 4 is a pH meter. 5 is a stirring device, 10 is a nickel carbonate addition valve, 11 is a chlorine gas addition valve, and 12 is a chlorine gas meter.

In Patent Document 1, a nickel chloride solution is obtained by mixing a nickel leaching solution having a high cobalt concentration and a nickel electrolytic waste solution, and when the nickel chloride solution is purified, the nickel concentration is 90 to 130 g / L and the cobalt concentration is 1. A 0 to 3.0 g / L nickel chloride solution was added, an oxidizing agent was added to the nickel chloride solution, the oxidation-reduction potential was 600 to 1200 mV (silver / silver chloride electrode standard), and the pH was adjusted to 4. using a neutralizing agent. A method of 0 to 6.0 is disclosed.
Such a method of Patent Document 1 can separate the cobalt and lead and control the amount of starch generated.

However, when adjusting the pH using a neutralizing agent, if the pH meter is held in the reaction vessel, the starch mainly composed of nickel hydroxide adheres to the glass electrode part, so the sensitivity of the pH meter is 20 minutes. It will fall by the extent, and the problem which pH cannot measure correctly will arise.
That is, the pH meter is composed of a glass electrode and a reference electrode, and the reference electrode has a small hole called a liquid junction, and the small hole in the weld has a small amount of adhesion of starch. However, the hole is partially blocked, and an error is likely to occur in pH measurement. Therefore, when used in a reaction vessel in which starch is generated, the sensitivity is immediately reduced.

Therefore, since the pH cannot be accurately grasped, there arises a problem that the amount of the neutralizing agent controlled by the pH is excessive or insufficient.
Specifically, for example, when the neutralizing agent is insufficient, the pH is too low, chlorine gas is lost in the air, and the chlorine gas concentration in the exhaust gas is 800 to 1000 ppm at the maximum. In this case, since the load of the exhaust gas abatement system increases, there is a concern that the environmental risk of chlorine leakage increases, and the amount of gas neutralizing agent used for the abatement increases.
On the other hand, if the neutralizing agent is excessive, the pH will rise too much and a large amount of nickel hydroxide will precipitate. In this case, since nickel hydroxide is a fine particle, the filterability of starch is significantly deteriorated, and solid-liquid separation becomes difficult.

  Due to the adhesion of starch, mainly nickel hydroxide, to this pH meter, the pH of the solution cannot be accurately grasped, and the amount of neutralizing agent added controlled by this pH becomes excessive or insufficient. On the other hand, for example, if acid cleaning of a pH meter is performed every 20 minutes, the pH can be accurately grasped, but manual cleaning causes a decrease in work efficiency due to an increase in work load, while an automatic acid cleaning device is installed. It can be developed and installed, but in this case, capital investment for development and installation of equipment is required.

  Therefore, in the oxidation neutralization treatment step, avoiding an increase in workload due to manual cleaning of the pH meter, for example, every 20 minutes, or without investing in equipment to install an automatic acid cleaning device for the pH meter, There has been a demand for an oxidation neutralization treatment method better than the prior art, which can stabilize the addition amount of the neutralizing agent using an index that can control the addition amount of the neutralizing agent instead of pH.

JP 2011-157604 A

  The present invention is intended to solve such problems, and avoids an increase in the work load due to manual cleaning of the pH meter, for example, every 20 minutes, or invests in an automatic pH meter acid cleaning device. In addition, an object of the present invention is to provide a method for oxidative neutralization of an aqueous nickel chloride solution that can stabilize the addition amount of a neutralizing agent using an index that can control the addition amount of a neutralizing agent instead of pH. is there.

  The first invention of the present invention is a pre-stage oxidative neutralization treatment and a post-stage oxidative neutralization treatment in which nickel chlorinated aqueous solution containing at least cobalt is added and treated while controlling the addition amounts of the oxidizing agent and the neutralizing agent. In the oxidation neutralization treatment method that produces an aqueous solution from which cobalt-containing hydroxide starch and cobalt have been removed through a staged oxidation neutralization treatment, the amount of neutralizing agent added in the subsequent oxidation neutralization treatment is determined by oxidation neutralization. An oxidation neutralization treatment method for an aqueous nickel chloride solution, characterized by controlling the oxidation-reduction potential (hereinafter referred to as ORP) value of the aqueous nickel chloride solution during the treatment as an index.

According to a second aspect of the present invention, the oxidizing agent for the subsequent oxidation neutralization treatment in the first aspect is chlorine gas, the neutralizing agent is at least one of nickel carbonate and basic nickel carbonate, and a redox potential (silver / Silver chloride electrode standard) is adjusted to a range of 900 to 1100 mV, and is an oxidation neutralization treatment method for an aqueous nickel chloride solution.

  A third invention of the present invention is an aqueous solution in which the nickel chloride aqueous solution in the first and second inventions has a nickel concentration of 90 to 130 g / L and a cobalt concentration of 0.001 to 3.0 g / L. This is a method for the oxidation neutralization treatment of a nickel chloride aqueous solution.

  According to the present invention, the pH meter is improved in work efficiency by avoiding an increase in work load due to troublesome work such as “manual cleaning every 20 minutes”, or the equipment of the pH meter automatic acid cleaning device By using an index that can control the amount of neutralizing agent in place of pH without investing, the amount of neutralizing agent can be stably controlled, improving work efficiency and cost-effectiveness. It is possible to achieve an industrially significant effect.

It is a manufacturing flowchart which shows the manufacturing process of electrical nickel. It is a schematic diagram explaining the addition method of the oxidizing agent and neutralizing agent in the oxidation neutralization process using the conventional pH as a control parameter | index. It is a schematic diagram explaining the addition method of the oxidizing agent and neutralizing agent in the oxidation neutralization process which used ORP of this invention as a parameter | index of control. Is a diagram showing the trend of the reaction vessel ORP (silver / silver electrode reference chloride) and chlorine concentration in the exhaust gas (Cl ₂₎ when the operation for 8 days in the first embodiment. Chlorine concentration in the reaction vessel with the exhaust gas ORP (silver / silver chloride electrode standard) when operating for 8 days in Comparative Example 1 is a diagram showing the trend of the (Cl _2).

  In the present invention, an oxidation neutralization treatment performed by adding an oxidizing agent and a neutralizing agent to a nickel chloride aqueous solution containing at least cobalt is performed in a two-stage process of a pre-stage oxidation neutralization treatment and a post-stage oxidation neutralization treatment. In addition, in the formation of an aqueous solution in which a cobalt-containing hydroxide starch is produced in the subsequent oxidation neutralization treatment (oxidation neutralization 2 in FIG. 1) and the cobalt is removed, the amount of neutralizing agent used is determined by oxidation neutralization. It adjusts according to the fluctuation | variation of ORP in a reaction tank, It is characterized by the above-mentioned.

The nickel chloride aqueous solution before treatment to be subjected to oxidation neutralization treatment contains at least cobalt, and also contains trace impurities such as iron, copper, lead, etc. If the nickel concentration is too low, the amount of liquid in the oxidation neutralization treatment step This is not preferable because it causes an increase. On the other hand, if the nickel concentration is too high, the chloride concentration increases, so cobalt tends to form a chloride complex and is difficult to precipitate.
Therefore, the nickel concentration is preferably 90 to 130 g / L, and the cobalt concentration is preferably 0.001 to 3.0 g / L.

As the oxidizing agent used in the oxidation neutralization treatment in the present invention, chlorine gas or sodium hypochlorite can be used, but chlorine gas which is not affected by impurities such as sodium is desirable.
On the other hand, nickel carbonate, basic nickel carbonate, sodium hydroxide or slaked lime can be used as the neutralizing agent, but when sodium ions or calcium ions are brought into the process, it is necessary to consider removal in a later step. Therefore, nickel carbonate or basic nickel carbonate that does not affect the composition of the aqueous nickel chloride solution is suitable.

Next, a method for adding an oxidizing agent and a neutralizing agent will be described. FIG. 3 shows the addition method. FIG. 3 is a schematic diagram for explaining a method of adding an oxidizing agent and a neutralizing agent in the oxidative neutralization treatment of the present invention, wherein 2 is a reaction tank, 3 is an ORP meter, 4 is a pH meter, 5 is a stirrer, A nickel carbonate addition valve, 11 is a chlorine gas addition valve, and 12 is a chlorine gas meter.
In the addition method shown in FIG. 3, the inventors have found that there is a correlation between the ORP value and the amount of chlorine gas (oxidant) loss into the air. It was found that the reaction was stabilized and the chlorine gas loss amount was reduced by controlling so as to be.

  Next, regarding the index in the control of the reaction system, the aqueous nickel chloride solution to be treated in the present invention produces a starch in the oxidative neutralization treatment. It is difficult to measure an accurate value over 20 minutes because of the adhesion of objects, but when measuring using ORP (oxidation-reduction potential) as an index, a metal electrode is used for the detection part of the ORP meter. Since there are no small holes such as entanglements, it has been found that a nickel chloride aqueous solution can be measured accurately for about 2 hours.

  On the other hand, the ORP meter needs to be periodically cleaned. When the ORP meter is lifted for this cleaning and immersed again, it may take a long time to obtain an accurate value after the ORP meter is immersed. Therefore, when the process is controlled using the ORP as an index, there is a problem that the control during this time cannot be performed accurately. Since the period during which this control cannot be performed accurately is long, the ORP is used as a process control index. Although it may be difficult to adopt the method, in the present invention, since the aqueous solution to be treated is a high-purity nickel chloride aqueous solution, such a problem does not occur, and the ORP meter is immersed again. The time required to obtain an accurate value is short.

Specifically, when the ORP meter is pulled up for cleaning, it takes about 3 minutes from the raising of the ORP meter to cleaning, re-immersion in an aqueous solution, and again obtaining an accurate value. Control of the oxidation neutralization process using ORP is possible.
Therefore, the ORP of the aqueous solution to be treated according to the present invention is measured using an ORP meter, and nickel carbonate as a neutralizing agent is added so that the ORP becomes constant.

This oxidation neutralization treatment is performed using the method of oxidation neutralization treatment according to the present invention shown in FIG.
Specifically, chlorine gas, which is an oxidizer, automatically controls the flow rate of chlorine gas by fixing the blowing ratio of chlorine gas to the amount of processing liquid. By this automatic control, impurities are removed and the amount of starch generated is adjusted.
Moreover, the addition amount of nickel carbonate which is a neutralizing agent is automatically added according to the reaction vessel ORP value.

  If the ORP measurement value is higher than the ORP set value in the addition amount of nickel carbonate, the addition amount of nickel carbonate is increased and the ORP is lowered. Conversely, if the ORP measurement value is lower than the ORP set value, the amount of nickel carbonate added is decreased to increase the ORP.

When the ORP based on the silver / silver chloride electrode standard is 900 mV or less, nickel carbonate is excessively added, and a large amount of nickel hydroxide with poor filterability is generated. Further, when ORP (silver / silver chloride electrode standard) is 1100 mV or more, nickel carbonate is insufficient and chlorine loss increases, which is not preferable.
Therefore, the ORP set value is preferably 900 to 1100 mV based on the silver / silver chloride electrode.

Moreover, you may measure pH regularly as an auxiliary | assistant parameter | index.
In the oxidative neutralization treatment according to the present invention, the pH becomes a matter of course, but if the pH is 5.0 or more, a large amount of nickel hydroxide with poor filterability is generated, which is not preferable. Moreover, since it becomes difficult to precipitate an impurity when pH becomes 4.0 or less, it is unpreferable. Therefore, it is preferable to adjust the ORP set value so that the pH is 4.0 to 5.0.

  Specifically, when the pH exceeds 5.0, the ORP measurement value may be adjusted to increase. Moreover, what is necessary is just to adjust so that an ORP measured value may decrease, when pH will be less than 4.0.

  The present invention will be further described below using examples.

The operation was performed for 8 days using a nickel chloride aqueous solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 0.001 to 0.006 g / L.
This nickel chloride aqueous solution was supplied to a reaction vessel having a capacity of 50 m ³ at a flow rate of 550 L / min, and chlorine gas having a chlorine concentration of 90 wt% was blown into the liquid by a constant blow of 99 kg / h.
The liquid supply amount was measured and controlled by an electromagnetic flow meter (not shown in FIG. 3) at the reaction tank inlet.

  In addition, nickel carbonate was added by using a slurry of 150 g / L, setting the reaction vessel ORP set value to 1065 mV, and controlling the amount of nickel carbonate added by the control method according to the present invention using an ORP meter. The ORP meter used was manufactured by Toa DKK Corporation.

A specific control method will be described with reference to FIG.
A process control computer (not shown) takes the reaction vessel ORP measurement value using the ORP meter 3, and reduces the difference between the reaction layer ORP measurement value and the preset reaction vessel ORP setting value by PID control. A signal was sent to the nickel carbonate addition valve 10. The amount of nickel carbonate added is adjusted by the opening degree of the nickel carbonate addition valve 10 based on the signal.

FIG. 4 shows the trend of the reaction vessel ORP (silver / silver chloride electrode standard) and the chlorine concentration (Cl ₂ ) in the exhaust gas when operated for 8 days in Example 1, and Table 1 shows the data at that time and the reaction vessel pH. The data is shown.
The reaction vessel ORP was continuously measured with the ORP meter 3 immersed in the reaction vessel 2. Moreover, chlorine gas was continuously measured with the chlorine gas meter 12 in the middle of the duct of the exhaust gas recovery apparatus provided on the reaction tank 2.

4 and Table 1, the variation of the reaction vessel ORP was 1056 to 1074 mV, the reaction vessel pH was 4.56 to 4.96, and the variation of the reaction vessel ORP was smaller than that of the conventional method.
Moreover, the maximum value of the chlorine concentration in the exhaust gas linked to the ORP value was 495 ppm, and the maximum value of the chlorine concentration in the exhaust gas could be reduced as compared with the conventional method.
Therefore, according to the method of adding nickel carbonate according to the present invention, the ORP can be accurately grasped, so that fluctuations in the amount of nickel carbonate added as a neutralizing agent can be suppressed and stable oxidation neutralization can be performed. .

  The operation was performed in the same manner as in Example 1, except that an aqueous nickel chloride solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 0.001 to 0.006 g / L was used, and the reaction vessel ORP set value was 1094 mV. .

As a result, the reaction vessel ORP was 1088 to 1100 mV, the reaction vessel pH was 4.60 to 5.00, and fluctuations in the reaction vessel ORP and the reaction vessel pH were smaller than in the conventional method.
Moreover, the maximum value of the chlorine concentration in the exhaust gas linked to the ORP value was 495 ppm, and the maximum value of the chlorine concentration in the exhaust gas could be reduced as compared with the conventional method.
Therefore, since the ORP can be accurately grasped, fluctuations in the amount of nickel carbonate added can be suppressed and stable oxidation neutralization can be performed.

  The operation was performed in the same manner as in Example 1 except that a nickel chloride aqueous solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 0.001 to 0.006 g / L was used, and the reactor ORP set value was 906 mV. It was.

As a result, the reaction vessel ORP was 900 to 912 mV, the reaction vessel pH was 4.06 to 4.46, and fluctuations in the reaction vessel ORP and the reaction vessel pH were smaller than those of the conventional method.
Moreover, the maximum value of the chlorine concentration in the exhaust gas linked to the ORP value was 498 ppm, and the maximum value of the chlorine concentration in the exhaust gas could be reduced as compared with the conventional method.
Therefore, since the ORP can be accurately grasped, fluctuations in the amount of nickel carbonate added can be suppressed and stable oxidation neutralization can be performed.

  The operation was performed in the same manner as in Example 1 except that a nickel chloride aqueous solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 2.2 to 3.0 g / L was used, and the reaction vessel ORP set value was set to 1094 mV. It was.

As a result, the reaction vessel ORP was 1088 to 1100 mV, the reaction vessel pH was 4.60 to 5.00, and fluctuations in the reaction vessel ORP and the reaction vessel pH were smaller than in the conventional method.
Moreover, the maximum value of the chlorine concentration in the exhaust gas linked to the ORP value was 495 ppm, and the maximum value of the chlorine concentration in the exhaust gas could be reduced as compared with the conventional method.
Therefore, since the ORP can be accurately grasped, fluctuations in the amount of nickel carbonate added can be suppressed and stable oxidation neutralization can be performed.

  The operation was performed in the same manner as in Example 1, except that an aqueous nickel chloride solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 2.2 to 3.0 g / L was used, and the reaction vessel ORP set value was 906 mV. went.

As a result, the reaction vessel ORP was 900 to 912 mV, the reaction vessel pH was 4.06 to 4.46, and fluctuations in the reaction vessel ORP and the reaction vessel pH were smaller than those of the conventional method.
Moreover, the maximum value of the chlorine concentration in the exhaust gas linked to the ORP value was 498 ppm, and the maximum value of the chlorine concentration in the exhaust gas could be reduced as compared with the conventional method.
Therefore, since the ORP can be accurately grasped, fluctuations in the amount of nickel carbonate added can be suppressed and stable oxidation neutralization can be performed.

(Comparative Example 1)
The operation was performed for 8 days using a nickel chloride aqueous solution having a nickel concentration of 97 to 130 g / L and a cobalt concentration of 0.005 to 0.007 g / L.
Chlorine gas was blown into the liquid at 97 kg / H. Further, the nickel carbonate was used in a slurry of 150 g / L, the target reaction tank pH was 4.7, and the amount of nickel carbonate added was controlled by a conventional control method using a pH meter.

A specific control method will be described with reference to FIG.
A process control computer (not shown) captures the reaction tank pH measurement value and signals to the nickel carbonate addition valve 10 to reduce the difference between the reaction tank pH measurement value and the reaction tank pH setting value by PID control. It was sent. The amount of nickel carbonate added was adjusted by the opening degree of the nickel carbonate addition valve 10 based on the transmitted signal.

The operation was performed in the same manner as in Example 1 except for the above-described method of blowing chlorine gas and adding nickel carbonate.
FIG. 5 shows the trend of the reaction vessel ORP (silver / silver chloride electrode standard) and the chlorine concentration in the exhaust gas when operated for 8 days, and Table 2 shows the data at that time and the reaction vessel pH.

According to the conventional method of adding nickel carbonate, since the pH cannot be accurately grasped, the amount of nickel carbonate added becomes unstable.
From FIG. 5 and Table 2, the variation of the reaction vessel ORP is 1034 to 1085 mV, the standard deviation of the reaction vessel ORP is 7.9 mV, the reaction vessel pH is 4.36 to 4.96, and the reaction vessel ORP and the reaction vessel The variation in pH was greater than in Example 1.
Further, the standard deviation of the chlorine concentration in the exhaust gas was 113 ppm, which was larger than that in Example 1. The maximum value of the chlorine concentration in the exhaust gas was also 870 ppm, which was larger than that in Example 1.

(Comparative Example 2)
The operation was performed in the same manner as in Example 1 except that a nickel chloride aqueous solution having a nickel concentration of 60 to 85 g / L and a cobalt concentration of 0.0005 to 0.0008 g / L was used and the reaction vessel ORP set value was 850 mV. It was.

In Comparative Example 2, since the nickel concentration was lower than the scope of the claims of the present invention, the liquid volume was increased and the productivity was lowered.
Moreover, since the reaction vessel ORP was 844 to 856 mV and the reaction vessel pH was 5.06 to 5.46, the addition amount of nickel carbonate as a neutralizing agent was excessive, and nickel hydroxide starch having poor filterability. Was generated in large quantities, causing problems in the solid-liquid separation process for treating the starch generated in this process.

(Comparative Example 3)
The operation was carried out in the same manner as in Example 1 except that an aqueous nickel chloride solution having a nickel concentration of 135 to 160 g / L and a cobalt concentration of 3.2 to 3.7 g / L was used, and the reaction vessel ORP set value was 1150 mV. It was.

In Comparative Example 3, since the nickel concentration is higher than the scope of the claims of the present invention, the chloride concentration increases, cobalt forms a chloride complex, and cobalt cannot be separated and removed as a hydroxide. It was.
Moreover, since reaction tank ORP became 1144-1156mV and reaction tank pH became 3.56-3.96, the addition amount of the nickel carbonate which is a neutralizing agent was insufficient, and chlorine loss increased.

2 Reaction tank 3 ORP meter 4 pH meter 5 Stirrer 10 Nickel carbonate addition valve 11 Chlorine gas addition valve 12 Chlorine gas meter

Claims (3)

From the nickel chloride aqueous solution containing at least cobalt, adding and processing while controlling the addition amount of the oxidizing agent and the neutralizing agent, through the two-stage oxidation neutralization treatment of the pre-stage oxidation neutralization treatment and the post-stage oxidation neutralization treatment, In the oxidation neutralization treatment method for producing an aqueous solution from which cobalt-containing hydroxide starch and cobalt have been removed,
An oxidation neutralization treatment method for a nickel chloride aqueous solution, wherein the addition amount of a neutralizing agent in the latter-stage oxidation neutralization treatment is controlled using an oxidation-reduction potential of the nickel chloride aqueous solution during the oxidation neutralization treatment as an index. The oxidizing agent in the post-stage oxidation neutralization treatment is chlorine gas, and the neutralizing agent is at least one of nickel carbonate and basic nickel carbonate,
The method for oxidizing and neutralizing an aqueous nickel chloride solution according to claim 1, wherein the oxidation-reduction potential (silver / silver chloride electrode reference) is adjusted to a range of 900 to 1100 mV.   The nickel chloride aqueous solution is an aqueous solution of nickel chloride aqueous solution according to claim 1 or 2, wherein the nickel chloride aqueous solution is an aqueous solution having a nickel concentration of 90 to 130 g / L and a cobalt concentration of 0.001 to 3.0 g / L. Processing method.

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