JP2009215611A - Method for purifying nickel chloride aqueous solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for purifying nickel chloride aqueous solution for improving filtering property of precipitates of iron hydroxide (III) in the formed slurry in the reaction-finish solution and for suppressing loss to the precipitates of nickel and cobalt, in the purifying method for precipitating and removing iron by adding a neutralizing agent to the nickel chloride aqueous solution containing the cobalt and the iron as impurity elements while injecting chlorine therein. <P>SOLUTION: The purifying method comprises precipitating and removing the iron by adding the neutralizing agent to the nickel-chloride aqueous solution while injecting the chlorine therein to perform the oxidation-neutralization reaction and by forming the slurry as the reaction finishing solution containing the iron hydroxide (III) precipitate. The neutralizing agent is mixed slurry obtained by mixing nickel-carbonate slurry and a repeating material divided at the ratio of 10-80% to the whole quantity of the reaction-starting solution, from the slurry in the reaction-finish solution, and pH of the oxidization-neutralization reaction is adjusted to 1.7-2.5 and oxidation-reduction potential (Ag/AgCl electrode base) is adjusted to 950-1,100 mV. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for purifying an aqueous nickel chloride solution. More specifically, a nickel chloride aqueous solution containing cobalt and iron as impurity elements is added with a neutralizing agent while blowing chlorine, and subjected to an oxidation neutralization reaction. In the purification method in which iron is precipitated and removed as iron (III) hydroxide, the filterability of the iron (III) hydroxide precipitate in the formed reaction final slurry is improved, and the loss of nickel and cobalt to the precipitate is reduced. The present invention relates to a method for purifying an aqueous nickel chloride solution that can be suppressed. Thereby, the iron concentration of the nickel chloride aqueous solution after refinement | purification can be reduced to 0.1 g / L or less calculated | required for manufacture of high purity electronickel.

  The purification method of nickel chloride aqueous solution is an important technique in the production of high-purity electro-nickel widely used as a superalloy material and a plating material. In general, a method comprising a leaching process, a liquid purification process, and an electrolysis process is used as a method for producing high-purity electronickel. For example, first, in the leaching step, nickel sulfide or nickel sulfide as a raw material is leached with chlorine gas to obtain a leachate. Subsequently, in the liquid purification step, the impurity element contained in the leachate is removed to obtain a high-purity nickel chloride aqueous solution. Thereafter, in the electrolysis step, the high-purity nickel chloride aqueous solution is used as an electrolytic solution, and nickel is electrodeposited on the cathode by an electrowinning method, which is recovered to obtain high-purity electro-nickel.

  In the above leachate, in addition to nickel, various metal elements contained in raw materials such as iron and cobalt are usually present as impurity elements. Therefore, in the liquid purification process, the impurity elements are combined by combining various methods. Separated and removed. As such a liquid purification process, for example, a process using a method called an oxidation neutralization method in which an oxidation reaction and a neutralization reaction are simultaneously performed (see, for example, Patent Documents 1 to 4) is known. . In the liquid purification process using this oxidation neutralization method, the impurity element is precipitated and removed as a hydroxide by adjusting the pH by adding a neutralizing agent and adjusting the oxidation-reduction potential by adding an oxidizing agent. . Here, sodium carbonate, sodium hydroxide, nickel carbonate, nickel hydroxide or the like is used as the neutralizing agent, and chlorine gas, hydrogen peroxide water or the like is generally used as the oxidizing agent. Is.

  However, in the liquid purification process using the oxidation neutralization method as described above, when the quality of impurity elements such as cobalt and iron in nickel sulfide raw materials such as nickel sulfide and nickel subsulfide increases, Since the content of the impurity element also increases, the amount of precipitate produced increases, and the load on the filtration device increases. Among these, especially iron becomes a fine hydroxide precipitate, so that its filterability is remarkably deteriorated. For this reason, an increase in the iron quality in the raw material reduces the processing capacity of the filtration device in addition to an increase in the amount of precipitates.If this effect is significant, a clear nickel chloride aqueous solution cannot be obtained. Occasionally, the production of electro nickel was hindered.

  As a solution to this, the liquid purification step is performed such that the pH of an aqueous nickel chloride solution containing at least cobalt and iron as impurity elements is 2.0 to 2.5, and the oxidation-reduction potential (Ag / AgCl electrode standard) is 450 to 900 mV. First step of adjusting and preferentially removing iron, and then adjusting pH to 4.0 to 6.0 and redox potential (Ag / AgCl electrode standard) to 600 to 1100 mV to remove cobalt. A method (for example, refer to Patent Document 5) comprising two steps with the second step is disclosed. According to this method, when refining the nickel chloride aqueous solution used for the production of high-purity electronickel, first, iron that significantly deteriorates the filterability of the precipitate is preferentially removed from the nickel chloride aqueous solution, and then nickel and cobalt are efficiently removed. Therefore, even if the iron quality in the raw material is high, it is possible to obtain a high-purity nickel chloride aqueous solution without increasing the load on the filtration device and making a large capital investment. I can do it. However, this method is not an essential solution because it does not improve the filterability itself of the precipitate containing iron hydroxide produced to a good state.

By the way, as a method for improving the filterability of the precipitate containing iron hydroxide, an acidic waste liquid containing a plurality of metal ions in addition to divalent iron ions and trivalent iron ions is supplied into the first reaction tank, In addition to oxidizing divalent iron ions to trivalent iron ions by means of chemical oxidation means or chemical oxidation means, a neutralizing agent is added to adjust the pH of the waste liquid to 3-5, and iron (III) hydroxide The main particles are generated, and then a part of the waste liquid slurry containing the particles is supplied to the second reaction tank, and the pH of the slurry in the second reaction tank is adjusted to 5 to 13 by adding an alkali agent. Then, after the particles are aggregated, the particles are returned to the first reaction tank, the slurry containing the aggregated particles is solid-liquid separated and concentrated, and then the concentrated slurry is dehydrated to form a cake ( For example, see Patent Document 6.). According to this method, it is possible to improve the filterability and dewaterability of the slurry containing iron hydroxide (III) by increasing the diameter of the iron hydroxide (III), and to produce a dehydrated cake with a low water content. It can be effectively used as an iron source in the industry.
However, this method is intended to remove metal elements such as iron in batches for waste liquids containing multiple metals such as pickling waste liquids and plating waste liquids, and metal mine drainage that is acidic and contains heavy metals. When applied to the purification method of nickel chloride aqueous solution containing iron and cobalt, nickel and cobalt contained in high concentration form hydroxides and are contained in iron (III) hydroxide precipitates and lost. Thus, there arises a problem that the yield is deteriorated.

Japanese Examined Patent Publication No. 3-126325 (first page) Japanese Patent Laying-Open No. 2005-104809 (first page, second page) JP-A-2005-248245 (first page, second page) JP 2008-13388 A (first page, second page) JP 2005-298309 A (first page, second page) Japanese Patent Laying-Open No. 2005-296866 (first page, second page)

  In view of the above-mentioned problems of the prior art, the object of the present invention is to add a neutralizing agent while blowing chlorine into an aqueous nickel chloride solution containing cobalt and iron as impurity elements, and subject to an oxidation neutralization reaction. In the purification method in which iron is precipitated and removed as iron (III) hydroxide, the filterability of the iron (III) hydroxide precipitate in the formed reaction final slurry is improved, and the loss of nickel and cobalt to the precipitate is reduced. An object of the present invention is to provide a method for purifying an aqueous nickel chloride solution that can be suppressed.

  In order to achieve the above object, the present inventors added a neutralizing agent while blowing chlorine into an aqueous solution of nickel chloride containing cobalt and iron as impurity elements, subjected to an oxidation neutralization reaction, and subjected to hydroxylation. In a method for purifying an aqueous nickel chloride solution in which iron is precipitated and removed as iron (III) hydroxide by forming a reaction end slurry containing iron (III) precipitate, the iron (III) hydroxide precipitate in the reaction end slurry As a result of intensive studies on the filterability of nickel and the loss of nickel and cobalt to the precipitate, as the neutralizing agent, a nickel carbonate slurry and a repetitive product divided at a specific ratio from the final reaction slurry were mixed. When the mixed slurry was used and the pH and oxidation-reduction potential of the oxidation neutralization reaction were adjusted to specific values, the precipitate of iron (III) hydroxide in the formed reaction final slurry was filtered. Improves the sex, it found that it is possible to suppress the loss to precipitate the nickel and cobalt, the present invention has been completed.

That is, according to the first invention of the present invention, a neutralizing agent is added to a nickel chloride aqueous solution containing cobalt and iron as impurity elements while blowing chlorine, and subjected to an oxidation neutralization reaction. (III) In a purification method of an aqueous nickel chloride solution in which iron is precipitated and removed as iron hydroxide (III) by forming a final reaction slurry containing precipitation,
The neutralizing agent is a mixed slurry obtained by mixing nickel carbonate slurry and a repetitive product divided from the reaction final solution slurry at a ratio corresponding to 10 to 80% with respect to the total amount of the reaction start solution, and the oxidation There is provided a method for purifying an aqueous solution of nickel chloride, characterized by adjusting the pH of the neutralization reaction to 1.7 to 2.5 and adjusting the oxidation-reduction potential (Ag / AgCl electrode standard) to 950 to 1100 mV.

  According to the second invention of the present invention, in the first invention, the nickel chloride aqueous solution has a nickel concentration of 140 to 200 g / L, a cobalt concentration of 1 to 5 g / L, and an iron concentration of 0. Provided is a method for purifying an aqueous nickel chloride solution, characterized in that it is from 8 to 3.5 g / L.

  According to the third invention of the present invention, in the first or second invention, the composition of the purified nickel chloride aqueous solution is characterized in that the iron concentration is 0.1 g / L or less, the nickel chloride aqueous solution A purification method is provided.

  In the method for purifying an aqueous nickel chloride solution of the present invention, a nickel chloride aqueous solution containing cobalt and iron as impurity elements is added with a neutralizing agent while blowing chlorine, subjected to an oxidation neutralization reaction, and iron is converted into iron hydroxide. In the purification method in which precipitation is removed as (III), the iron hydroxide (III) precipitate in the formed reaction final slurry can be made into particles having a large diameter, and the filterability and dewaterability of the slurry containing it can be improved. While improving greatly, the loss to the precipitation of nickel and cobalt can be suppressed. Therefore, even when the iron quality in the nickel raw material is high, an increase in the load on the filtration device can be suppressed, and it is suitable as an electrolyte used for the production of high-purity electro-nickel without making a large capital investment. Moreover, since a high-purity nickel chloride aqueous solution having an iron concentration of 0.1 g / L or less can be obtained, its industrial value is extremely high.

Hereinafter, the purification method of the nickel chloride aqueous solution of the present invention will be described in detail.
The method for purifying an aqueous nickel chloride solution of the present invention comprises adding a neutralizing agent while blowing chlorine into a reaction starting solution consisting of an aqueous nickel chloride solution containing cobalt and iron as impurity elements, and subjecting to an oxidation neutralization reaction, In a purification method of an aqueous nickel chloride solution in which iron is precipitated and removed as iron (III) hydroxide by forming a reaction end slurry containing iron (III) hydroxide precipitate,
The neutralizing agent is a mixed slurry obtained by mixing a nickel carbonate slurry and a repetitive product divided from the reaction final solution slurry at a ratio of 10 to 80% with respect to the total amount of the reaction start solution, and The pH of the oxidation neutralization reaction is adjusted to 1.7 to 2.5, and the oxidation-reduction potential (Ag / AgCl electrode standard) is adjusted to 950 to 1100 mV.

In the above method, a neutralizing agent is added to a reaction starting solution composed of a nickel chloride aqueous solution containing cobalt and iron as impurity elements while blowing chlorine as an oxidizing agent, and subjected to an oxidation neutralization reaction. (III) By forming a reaction final solution slurry containing precipitation, a purified solution containing nickel and cobalt is obtained from this, and iron is precipitated and removed as iron (III) hydroxide. At this time, while controlling the pH and oxidation-reduction potential of the oxidation neutralization reaction to predetermined values, a part of the formed reaction final solution slurry is divided from the liquid feed to the filter for obtaining the purified liquid, It is important to mix with the nickel carbonate slurry and repeat as a neutralizer.
Thereby, as the composition of the nickel chloride aqueous solution after purification, the iron concentration required for the production of high-purity electronickel is 0.1 g / L or less, and iron hydroxide ( III) The filterability of precipitation can be improved and the loss of nickel and cobalt to precipitation can be suppressed.

Below, each requirement of the oxidation neutralization reaction which concerns on the method of this invention is demonstrated with the effect.
The oxidation neutralization reaction used in the above method is represented by the following formula (1).

Formula (1): FeCl ₂ + 3 / 2H ₂ O + 1 / 2Cl ₂ + 3 / 2NiCO ₃ ⇒ Fe (OH) ₃ + 3 / 2NiCl ₂ + 3 / 2CO ₂

Here, the first iron chloride in the liquid is oxidized and neutralized with nickel carbonate as a neutralizing agent and chlorine as an oxidizing agent to produce iron (III) hydroxide.
The reaction does not proceed sufficiently when the pH is lower than a predetermined value. On the other hand, when the pH is 3.0 or more, nickel and cobalt in the liquid are neutralized and hydrolyzed, precipitate as hydroxide, and are contained in the iron (III) hydroxide precipitate, resulting in nickel loss and cobalt. Loss increases.

  The nickel chloride aqueous solution used in the above method is not particularly limited, and nickel chloride aqueous solutions containing cobalt, iron and other impurity elements are used. Among them, nickel such as nickel sulfide and nickel subsulfide is particularly preferable. A leaching solution containing cobalt and iron as impurity elements, which is produced in a wet refining method in which sulfide raw material is leached with chlorine gas and the obtained nickel chloride aqueous solution is purified and then electro nickel is obtained by electrowinning, is preferred. Used. The composition of such a leachate is not particularly limited. For example, the nickel concentration is 140 to 200 g / L, the cobalt concentration is 1 to 5 g / L, and the iron concentration is 0.8 to 3.5 g / L. L.

  As pH of the oxidation neutralization reaction used for the said method, it is 1.7-2.5, Preferably it is 2.0-2.2. That is, when the pH is less than 1.7, the iron concentration in the reaction final solution is not sufficiently lowered, and for example, a purified solution having an iron concentration of 0.1 g / L or less cannot be obtained. Here, the pH in the reaction vessel is controlled by supplying a mixed slurry used as a neutralizing agent.

  The oxidation-reduction potential (Ag / AgCl electrode standard) of the oxidation neutralization reaction used in the above method is 950 to 1100 mV. That is, when the oxidation-reduction potential (Ag / AgCl electrode standard) is less than 950 mV, the above reaction is difficult to occur. On the other hand, when it exceeds 1100 mV, nickel and cobalt are also oxidized, so that they are precipitated by the neutralization reaction and nickel loss occurs. In addition to increasing the cobalt loss, the utilization rate of the chlorine gas to be blown in is reduced, leading to cost deterioration. Here, it is preferable to set the oxidation-reduction potential (Ag / AgCl electrode reference) to 1000 to 1050 mV in order to keep nickel loss and cobalt loss low while more reliably removing iron. Here, the oxidation-reduction potential in the reaction vessel is controlled by the amount of chlorine gas blown.

  The mixed slurry used as a neutralizing agent in the above method is a mixture of a nickel carbonate slurry and a repetitive product divided in a ratio corresponding to 10 to 80% with respect to the total amount of the reaction start solution from the reaction end solution slurry. The pH of the mixed slurry is not particularly limited, but is preferably 3.5 to 4.5. At this time, aggregation of iron hydroxide (III) particles contained in the reaction final solution slurry proceeds. Here, the pH is adjusted by the supply amount of the nickel carbonate slurry. In the mixed slurry, many metals such as iron, nickel, and cobalt are precipitated as hydroxides, but are then added relatively early to the reaction tank having a pH of 1.7 to 2.5. At this time, hydroxides other than iron (III) hydroxide are easily dissolved again.

  Therefore, in the above method, by using the mixed slurry as a neutralizing agent, the iron (III) hydroxide newly generated in the reaction vessel is aggregated on the surface of the aggregated iron hydroxide (III) particles, By integrating, dense particles having a large particle diameter can be obtained, so that the filterability of the reaction final slurry is improved.

In the above method, the ratio of the repetitive product divided from the reaction end solution slurry to the total amount of the reaction start solution supplied to the reaction vessel (hereinafter referred to as the reaction end solution slurry repetition rate, (Repeated flow rate ÷ reaction starting solution flow rate) × 100 means a value obtained by 10) to 80%.
That is, when the repetition rate is less than 10%, the filterability of iron (III) hydroxide particles in the reaction final slurry is insufficient. On the other hand, as the repetition rate increases, the particle size of the iron (III) hydroxide particles increases and the filterability improves. However, if it exceeds 80%, no further effect can be obtained, and conversely the optimal repetition. Decrease compared to rate. This phenomenon is thought to be due to a decrease in the residence time in the reaction vessel, and the grain size becomes fine due to grain growth inhibition and grain breakage by the pump. Further, when the residence time in the reaction vessel is maintained at a predetermined value, the increase in the repetition rate causes a reduction in the processing amount of the nickel chloride aqueous solution supplied as a reaction starting solution in proportion thereto. Therefore, specifically, the optimum repetition rate is selected while confirming the filterability at the repetition rate, but it is preferable to select the optimum repetition rate according to the scale and structure of the apparatus to be used. .

The relationship between the repetition rate of the reaction end slurry in the above method, the average particle size of the reaction end slurry and the average filtration rate will be described with reference to the drawings.
FIG. 1 is a graph showing the relationship between the repetition rate of the reaction end slurry and the average particle size of the particles in the reaction end slurry. FIG. 1 shows that there is a positive correlation between the two. Moreover, FIG. 2 is a figure showing the relationship between the repetition rate of a reaction final liquid slurry, and an average filtration rate. FIG. 2 shows that there is a positive correlation between the two. From these relationships, it can be seen that the repetition of the reaction final slurry in the method of the present invention works effectively.

The liquid purification equipment used in the above method is not particularly limited, but for example, a stirrer for performing an oxidative neutralization reaction, a reaction tank with a chlorine blowing tube, and a reaction final liquid slurry from the reaction tank. The equipment is composed of a receiving tank with a stirrer, a neutralizer supply tank with a stirrer that mixes repetitive nickel carbonate slurry and reaction final slurry, a pressure filter that separates iron precipitates, and its supply tank. It is done. Here, a fixed amount of nickel chloride aqueous solution as a reaction start solution is supplied to the reaction tank, the overflow of the reaction tank is sent to the receiving tank, and the discharge pipe of the extraction pump provided in the receiving tank is branched. Can be sent to the supply tank of the pressure filter, and the other can be sent to the neutralizer supply tank.
The nickel carbonate slurry was pumped to the neutralizer supply tank. The reaction vessel is provided with a pH meter and an oxidation-reduction potential (ORP) meter, and a mixed slurry of nickel carbonate slurry and reaction final slurry from the neutralizer supply tank so that the value of the pH meter maintains a set value. Was added. Then, chlorine gas was blown from the chlorine blowing pipe so that the value of the ORP meter maintained the set value.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. The evaluation methods used in Examples and Comparative Examples were as follows.
(1) Metal analysis: ICP emission analysis was performed.
(2) Measurement of average filtration rate of reaction final solution slurry: It was performed by suction filtration using Nutsche. The filter paper used is No. 5C.
(3) Measurement of average particle diameter of particles in reaction final solution slurry: Measured with Microtrac (manufactured by Honeywell, model number: 9320-X100).

Example 1
The nickel chloride aqueous solution was purified using the actual scale equipment of the above liquid purification equipment. Here, the effective volume of the reaction tank was 45 m ³ , the effective volume of the receiving tank for the reaction final solution slurry was 25 m ³ , and the effective volume of the neutralizing agent supply tank was 1 m ³ .
The nickel chloride aqueous solution used as the reaction starting solution is a leachate obtained by leaching a nickel sulfide raw material with chlorine gas, and has a composition of nickel concentration of 170 to 190 g / L and cobalt concentration of 2.5 to 4 0.0 g / L and the iron concentration was 1.64 g / L. The nickel carbonate slurry is prepared by adding nickel carbonate (manufactured by Sumitomo Metal Mining Co., Ltd.) to water.
Here, the conditions were set so that the residence time of the nickel chloride aqueous solution in the reaction vessel was 50 minutes and the repetition rate of the reaction final slurry was 60%, and the pH in the reaction vessel was 2.0, and ORP (Ag / AgCl electrode standard) was set to 1050 mV, and after the operation reached a stable state as a whole, the average filtration rate of the reaction end slurry, the average particle size of the particles in the reaction end slurry, and the pressure The iron concentration of the purified solution obtained with a filter was determined. In addition, pH during operation was 1.9 to 2.0, and ORP (Ag / AgCl electrode standard) was 1040 to 1050 mV.
As a result, the average filtration rate was 12.0 L / m ² / min, and the average particle size was 7.4 μm. Moreover, the iron concentration of the refinement | purification liquid was 0.1 g / L or less, and the nickel loss rate and the cobalt loss rate were 0.08% and 0.4%, respectively.

(Examples 2 to 4)
The reaction final slurry was changed in the same manner as in Example 1 except that the repetition rate of the final reaction slurry was 10% (Example 2), 30% (Example 3), and 80% (Example 4). The average filtration rate and the average particle size of the particles in the final reaction slurry were determined. The results are shown in Table 1. In addition, the value similar to Example 1 was obtained for the nickel loss rate and the cobalt loss rate.

(Comparative Example 1)
The average filtration rate of the reaction end slurry and the reaction end slurry were the same as in Example 1 except that the reaction end slurry was not repeated using the above-described liquid purification equipment, but was operated in a batch reaction. The average particle size of the particles inside was determined. The results are shown in Table 1.

(Comparative Example 2)
The average filtration rate of the reaction end solution slurry and the average particle size of the particles in the reaction end solution slurry were determined in the same manner as in Example 1 except that the repetition rate of the reaction end solution slurry was 90%. The results are shown in Table 1.

  From Table 1, in Examples 2 to 4, the average particle size of the particles is larger and the filtration rate is higher than in Comparative Example 1 in which the reaction final solution slurry is not repeated due to an increase in the repetition rate of the reaction final solution slurry. I understand that However, in Comparative Example 2, the filtration rate is lower than that in Example 4. This is presumably because when the repetition rate is increased above a certain repetition rate, non-uniformity in the reaction vessel, breakage of grains due to a repeated pump, and the like occur. Moreover, considering the reduction in the amount of nickel chloride aqueous solution supplied as the reaction starting solution, the optimum repetition rate under this condition is 80% or less.

(Example 5)
Except that the pH set value in the reaction vessel was 1.7 and the ORP set value was 980 mV, the operation was carried out in the same manner as in Example 1, and the average filtration rate of the reaction end solution slurry, The average particle diameter of the particles and the iron concentration of the purified liquid obtained with a pressure filter were determined. As a result, the average filtration rate was 8.5 L / m ² / min, and the average particle size was 5.5 μm. Moreover, the iron concentration of the purified liquid was 0.1 g / L or less, and the nickel loss rate and the cobalt loss rate were 0.05% and 0.3%, respectively, which were slightly lower than Example 1.

(Example 6)
The operation was carried out in the same manner as in Example 1 except that the pH set value in the reaction tank was 2.5 and the ORP set value was 1100 mV, and the average filtration rate of the reaction end slurry and the particles in the reaction end slurry And the iron concentration of the purified solution obtained with a pressure filter were determined. As a result, the average filtration rate was 18.7 L / m ² / min, and the average particle size was 7.1 μm. Further, the iron concentration of the purified liquid was 0.1 g / L or less, and the nickel loss rate and the cobalt loss rate were 0.11% and 1.1%, respectively, which were slightly higher than Example 1.

(Comparative Example 3)
When the operation was carried out in the same manner as in Example 1 except that the pH set value in the reaction vessel was 1.5 and the ORP set value was 930 mV, there was almost no generation of iron (III) hydroxide, Could not be removed.

(Comparative Example 4)
The operation was carried out in the same manner as in Example 1 except that the pH set value in the reaction tank was 2.9 and the ORP set value was 1120 mV, and the average filtration rate of the reaction end slurry and the particles in the reaction end slurry The average particle size was determined. As a result, the average filtration rate was 17.7 L / m ² / min, and the average particle size was 7.7 μm. Although the average filtration rate and average particle size were good, the nickel loss rate and the cobalt loss rate were as high as 0.15% and 2.0%, respectively. .

As mentioned above, in Examples 1-6, since it was performed according to the method of the present invention in the repetition rate of the reaction final solution slurry, and the pH and ORP of the oxidation neutralization reaction, the iron concentration of the nickel chloride aqueous solution after purification was 0.1 g / L or less, and the iron hydroxide (III) precipitate in the formed slurry at the end of the reaction can be made into particles with a large diameter, greatly improving the filterability of the slurry containing it, It turns out that the loss to the precipitation of nickel and cobalt can be suppressed.
On the other hand, in Comparative Examples 1 to 4, since the repetition rate of the reaction final slurry, the pH of the oxidation neutralization reaction, and the ORP do not meet these conditions, filterability, nickel loss rate, and cobalt loss rate It can be seen that satisfactory results cannot be obtained by any of the treatment amounts of the aqueous nickel chloride solution supplied as the reaction starting solution.

  As is clear from the above, the nickel chloride aqueous solution purification method of the present invention is subjected to an oxidation neutralization reaction by adding a neutralizing agent while blowing chlorine into a nickel chloride aqueous solution containing cobalt and iron as impurity elements. In the method for purifying an aqueous nickel chloride solution in which iron is precipitated and removed as iron (III) hydroxide, the filterability of the iron (III) hydroxide precipitate in the formed reaction final slurry is improved, and nickel and cobalt It is used as a method for suppressing loss to precipitation, and is particularly preferably used for obtaining a high-purity nickel chloride aqueous solution used for producing high-purity electronickel.

It is a figure showing the relationship between the repetition rate of a reaction end liquid slurry, and the average particle diameter of the particle | grains in a reaction end liquid slurry. It is a figure showing the relationship between the repetition rate of a reaction final liquid slurry, and an average filtration rate.

Claims (3)

A neutralizing agent is added to a nickel chloride aqueous solution containing cobalt and iron as impurity elements while blowing chlorine, and subjected to an oxidation neutralization reaction to form a reaction final slurry containing iron (III) hydroxide precipitate. In the method for purifying an aqueous nickel chloride solution in which iron is precipitated and removed as iron (III) hydroxide,
The neutralizing agent is a mixed slurry obtained by mixing nickel carbonate slurry and a repetitive product divided from the reaction final solution slurry at a ratio corresponding to 10 to 80% with respect to the total amount of the reaction start solution, and the oxidation A method for purifying an aqueous nickel chloride solution, comprising adjusting a pH of a neutralization reaction to 1.7 to 2.5 and an oxidation-reduction potential (Ag / AgCl electrode standard) to 950 to 1100 mV.   The composition of the nickel chloride aqueous solution has a nickel concentration of 140 to 200 g / L, a cobalt concentration of 1 to 5 g / L, and an iron concentration of 0.8 to 3.5 g / L. The method for purifying the nickel chloride aqueous solution as described.   The method of purifying a nickel chloride aqueous solution according to claim 1 or 2, wherein the composition of the nickel chloride aqueous solution after purification has an iron concentration of 0.1 g / L or less.

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