JP4124071B2 - Purification method of nickel chloride aqueous solution - Google Patents

Description

  The present invention relates to a method for purifying a nickel chloride aqueous solution. More specifically, the present invention relates to a method for efficiently removing an impurity element forming a chlorine complex, particularly zinc, contained in a nickel chloride aqueous solution with simple equipment and at low cost. About.

  Conventionally, nickel matte, which is a nickel sulfide concentrate obtained from nickel ore by a dry smelting method, has generally been used as a raw material for nickel refining. In recent years, with the active recycling of various scraps and intermediates in the refining process, and the practical application of wet refining methods such as sulfuric acid leaching using low nickel grade laterite ore as raw material ore, new nickel raw materials As a result, new nickel-containing materials have been the subject of nickel refining.

As an impurity element of nickel matte, which is a conventional raw material, the content of zinc that is easily removed by dry smelting was extremely small, but the new nickel raw material is a wet separation treatment such as a neutralization method or a sulfurization method. Therefore, zinc is usually contained together with copper, cobalt, iron and other impurity elements at a concentration of several hundred ppm to several weight percent.
When the new nickel raw material containing zinc and other impurity elements is leached with chlorine gas, and the resulting nickel chloride aqueous solution is purified and then processed by a wet refining process in which electro nickel is obtained by electrolysis, Since the contained zinc cannot be removed sufficiently by the conventional nickel refining process, a new zinc removal step is required.

That is, in the nickel chloride aqueous solution, zinc forms a chloride ion complex such as ZnCl ₄ ²⁻ . Therefore, when removing zinc as a sulfide by blowing hydrogen sulfide gas as a sulfiding agent, the removal efficiency is lower than when removing zinc in an aqueous solution of nickel sulfate as a sulfide, so that zinc is completely removed. This involves a large amount of nickel coprecipitation. Further, at this time, since an aeration treatment process of the mother liquor containing hydrogen sulfide is required, there is a problem that the capital investment cost increases.

In addition, since zinc forms hydroxide at a lower pH than nickel, zinc can be selectively removed to some extent by the neutralization method, but even in this case, in order to remove it to a low concentration Since it is necessary to make the pH higher than 6, coprecipitation of a large amount of nickel is unavoidable as well, which is not a desirable method.
In addition, although zinc can be separated using a solvent extraction method, it is not possible to employ a large-scale solvent extraction facility because of the problem of capital investment cost.
As described above, in order to remove zinc, a large-scale capital investment or a significant decrease in nickel yield was unavoidable.

  As a solution to this problem, a method using an ion exchange resin has been proposed. For example, nickel ions are adsorbed on an anion exchange resin by adsorbing metal ions forming a chloride complex such as cobalt, zinc, and iron in an aqueous cobalt chloride solution. Etc. (see, for example, Patent Document 1), nickel chloride aqueous solution after removing cobalt by oxidative neutralization method is in contact with anion exchange resin, and zinc and chromium are adsorbed and removed at once There is a way to do it. According to this method, zinc in an aqueous nickel chloride solution can be removed to a low concentration. However, when an impurity element that forms a chlorine complex is contained in the aqueous nickel chloride solution, depending on the type and concentration, it may be negatively affected. The life of the ion exchange resin is shortened, causing a problem in processing cost.

In view of the above situation, there is a demand for a method for efficiently removing impurity elements forming a chlorine complex, particularly zinc, contained in an aqueous nickel chloride solution with simple equipment and at low cost.
JP 2001-20021 (first page, second page)

  In view of the above-mentioned problems of the prior art, an object of the present invention is a method for efficiently removing an impurity element forming a chlorine complex, particularly zinc, contained in an aqueous nickel chloride solution with simple equipment and at low cost. Is to provide.

  In order to achieve the above object, the present inventors have conducted extensive research on a method for purifying a nickel chloride aqueous solution containing an impurity element that forms zinc or other chlorine complexes. After adjusting and oxidative neutralization, when processed in the step of ion exchange using an anion exchange resin, it was found that an impurity element forming a chlorine complex, particularly zinc, can be efficiently removed, and the present invention. Was completed.

That is, according to the first invention of the present invention, there is provided a method for purifying an aqueous nickel chloride solution containing an impurity element that forms zinc or another chlorine complex,
The nickel concentration of the aqueous nickel chloride solution is adjusted to 90 to 130 g / L , the oxidation-reduction potential is adjusted to 600 to 1200 mV with a silver / silver chloride electrode standard, and the pH is adjusted to 4.0 to 6.0, followed by oxidation neutralization, A first step of removing impurity elements, and a second step of subjecting the purified liquid obtained in the first step to ion exchange using an anion exchange resin and adsorbing and removing zinc. A method for purifying an aqueous nickel solution is provided.

According to the second invention of the present invention, the first invention further includes a step of contacting the purified liquid obtained in the first step with activated carbon prior to the second step. A method for purifying an aqueous nickel chloride solution is provided.

  The method for purifying an aqueous solution of nickel chloride according to the present invention is a method capable of efficiently removing impurity elements forming a chlorine complex, particularly zinc, contained in an aqueous solution of nickel chloride, with simple equipment and at low cost. The industrial value is extremely large.

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 is a method for purifying an aqueous nickel chloride solution containing an impurity element forming zinc or other chlorine complex, and adjusting the Ni concentration, redox potential and pH of the aqueous nickel chloride solution. The first step of subjecting to oxidative neutralization to remove the impurity elements, and the purified solution obtained in the first step to ion exchange using an anion exchange resin to remove zinc These steps are included.

  In the present invention, prior to the second process step of removing zinc by ion exchange using an anion exchange resin, in the first step, the Ni concentration, redox potential and pH of the raw nickel chloride aqueous solution are adjusted. It is important to preliminarily remove impurity elements that form a chlorine complex other than zinc by adjusting and subjecting to oxidative neutralization. Thereby, in the second step, the lifetime of the anion exchange resin can be greatly improved, and zinc can be efficiently removed. That is, if the impurity element forming the chlorine complex remains, it is adsorbed to the anion exchange resin together with zinc during ion exchange, so that the breakthrough point of the resin is accelerated, but this is prevented.

  The technical background of the breakthrough of the resin will be specifically described. Using nickel chloride aqueous solution with Ni concentration of 120 g / L and cobalt, copper, iron, and zinc concentrations of 0.001 g / L or less, the zinc concentration is 0.005 g / L, and the concentrations of cobalt, copper, and iron Are both 0.001 g / L or less of a test solution and a zinc concentration of 0.005 g / L and a cobalt and iron test solution of 0.5 g / L. Comparison of zinc removal by ion exchange using For preparation of zinc, cobalt and iron, reagent grade zinc chloride, cobalt chloride and ferric chloride were used, respectively.

  250 mL of each test solution is separately collected in a glass beaker, 15 mL of anion exchange resin (Amberlite IRA400, manufactured by Organo) is added to each, and the mixture is heated to 50 ° C. and stirred with a stirrer. The zinc concentration of the final solution was analyzed. As a result, the test solution containing no cobalt and iron was removed to a zinc concentration of 0.0001 g / L or less, but the test solution containing cobalt and iron was removed only to a zinc concentration of 0.001 g / L. Indicated. Here, in order to maintain the zinc quality in electronickel obtained by electrolysis at a level of 10 ppm or less, it is necessary to reduce the zinc concentration in the nickel chloride aqueous solution supplied to electrolysis to 0.0001 g / L or less. There is. That is, prior to ion exchange using an anion exchange resin, it was shown that it is important to remove impurity elements that form a chlorine complex other than zinc in advance.

(1) Nickel chloride aqueous solution The nickel chloride aqueous solution used in the present invention is not particularly limited, and a nickel chloride aqueous solution containing zinc and other impurity elements is used. Chloride containing zinc, cobalt, copper, iron, noble metal elements and other impurity elements that form chlorine complexes obtained in a wet refining process in which electrolytic nickel is obtained by electrolysis after purification of the resulting nickel chloride aqueous solution. A nickel aqueous solution is preferably used.

(2) 1st process The 1st process of this invention adjusts Ni density | concentration of the said nickel chloride aqueous solution, oxidation-reduction potential, and pH, attaches to oxidation neutralization, and removes the said impurity element as a hydroxide. It is a process.
The Ni concentration of the nickel chloride aqueous solution in the first step is not particularly limited, but is preferably 90 to 130 g / L, and more preferably 100 to 120 g / L. That is, a nickel chloride aqueous solution obtained by leaching a nickel raw material with chlorine gas usually has a Ni concentration of about 170 g / L, but a chlorine ion in which a chlorine complex of an impurity element such as cobalt, copper, or iron becomes unstable. Dilute to concentration and perform oxidative neutralization.

  This utilizes the difference in stability of each element when forming a chlorine complex in an aqueous chloride solution. The lower the chloride ion concentration, the more unstable the cobalt complex, copper, and iron become, and the easier it is to remove by oxidation neutralization. However, when diluted, the liquid volume increases significantly, and the equipment capacity needs to be increased. . Therefore, the Ni concentration is selected to be 90 g / L or more corresponding to the chlorine ion concentration at which zinc can form a chloride ion complex. On the other hand, when the Ni concentration exceeds 130 g /, cobalt, copper, and iron are reduced to a concentration that can minimize the influence of inhibiting the adsorption of zinc in the second step, for example, 0.01 g / L or less. Can not be removed. Here, for diluting the nickel chloride aqueous solution, it is preferable to repeatedly use an electrolytic waste solution of nickel electrolysis.

  The oxidation-reduction potential (silver / silver chloride electrode standard) of the aqueous nickel chloride solution in the first step is not particularly limited, but is preferably 600 to 1200 mV, more preferably 1000 to 1200 mV. That is, when the oxidation-reduction potential (silver / silver chloride electrode standard) is less than 600 mV, the oxidation is insufficient and cobalt, copper, and iron are not sufficiently removed. On the other hand, when it exceeds 1200 mV, the amount of Ni coprecipitate increases due to oxidation of nickel. The oxidizing agent used here is not particularly limited, but chlorine gas that does not cause accumulation of impurities is preferable.

  Although pH of the nickel chloride aqueous solution in a 1st process is not specifically limited, 4.0-6.0 are preferable and 4.0-5.0 are more preferable. That is, if pH is less than 4.0, neutralization reaction is inadequate and cobalt, copper, and iron are not removed sufficiently. On the other hand, when the pH exceeds 6.0, the amount of coprecipitation due to the neutralization reaction of nickel increases. The pH adjuster used here is not particularly limited, and an alkali salt is used. Among them, nickel hydroxide, basic nickel carbonate, and nickel carbonate that do not accumulate impurities are preferable.

(3) Second step The second step of the present invention is a step of subjecting the purified liquid obtained in the first step to ion exchange using an anion exchange resin, and adsorbing and removing zinc. . The purified solution obtained in the first step has been removed to a concentration of impurity elements such as cobalt, copper, iron and the like to 0.01 g / L or less, so that the adsorption of zinc is inhibited in the second step. The impact can be minimized. The resin adsorbed with zinc is washed with a hydrochloric acid solution, and after the adhered nickel chloride aqueous solution is recovered, an elution operation is performed using water.

The pH of the adsorption operation in the second step is not particularly limited, but is selected to be 6.0 or less, at which the neutralization reaction of nickel hardly occurs. That is, the purified liquid obtained from the first step is used without adjustment.
The temperature of the adsorption operation in the second step is not particularly limited, but is preferably 30 to 70 ° C.

  The operation method used in the second step is not particularly limited, and a method using a column packed with a commercially available anion exchange resin is preferable. As a result, the adsorbing operation can be continuously performed at a predetermined liquid passing rate until the resin adsorbing ability breaks through, which is efficient.

(4) Step of contacting activated carbon In the present invention, if necessary, prior to the second step, a step of contacting the purified liquid obtained in the first step with activated carbon can be included. As a result, when dissolved chlorine or a trace amount of noble metal element is present, it is adsorbed and removed by activated carbon, so that it is possible to further suppress a decrease in zinc adsorption capacity in ion exchange. That is, dissolved chlorine and noble metal elements that inhibit zinc adsorption of the ion exchange resin are removed.

The step of performing the contact treatment is not particularly limited, but a method using a column packed with commercially available activated carbon such as wood-based, coal-based, and coconut-based activated carbon is preferable.
Suitable for nickel electrolysis, in which impurity elements such as cobalt, copper, iron, and zinc are removed by treating an aqueous solution of nickel chloride containing an impurity element that forms zinc or other chlorine complexes based on the above steps. A purified solution is obtained.

  EXAMPLES The present invention will be described in more detail below with reference to examples of the present invention, but the present invention is not limited to these examples. In addition, the analysis of the metal used in the Example was performed by the atomic absorption method.

(Example 1)
In a wet refining process in which nickel raw material is leached with chlorine gas and the resulting nickel chloride aqueous solution is purified by oxidation neutralization treatment to obtain electro nickel by electrolysis, the produced nickel chloride aqueous solution is used to The process and the second process were performed.
(1) First Step First, in the process, the nickel chloride aqueous solution before the oxidation neutralization treatment was diluted with the electrolytic waste liquid of the process to adjust the Ni concentration to 120 g / L. Next, a predetermined amount of reagent primary zinc chloride was added to adjust the raw material nickel chloride aqueous solution, and then an oxidation neutralization treatment was performed under the following conditions, and the resulting precipitate was filtered and obtained. The composition of the purified solution was analyzed. The results are shown in Table 1. Table 1 also shows the composition of the raw material nickel chloride aqueous solution.

[Conditions for oxidation neutralization]
(1) Oxidation conditions: Chlorine gas was blown as an oxidizing agent, and the oxidation-reduction potential (silver / silver chloride electrode standard) was adjusted to 1000 mV.
(2) Neutralization conditions: Nickel carbonate (manufactured by Sumitomo Metal Mining Co., Ltd.) was added as a pH regulator to adjust the pH to 4.5.

  From Table 1, it can be seen that in the first step of the present invention, cobalt, copper and iron are removed to 0.001 g / L or less, while the removal of zinc does not proceed.

(2) Second step As the purified liquid obtained through the first step, reagent grade zinc chloride is added to the nickel chloride aqueous solution after the oxidation neutralization treatment in the above process, and the adsorption shown in Table 2 A starting solution was prepared.

  Next, these liquids were passed through a column packed with 200 mL of an anion exchange resin (Amberlite IRA400, manufactured by Organo). The adsorption conditions were a flow rate SV (expressed in multiples of resin volume used / hour) 5 and a temperature of 50 ° C. The zinc concentration of the final liquid that passed through the column was analyzed. The results are shown in Table 3.

  From Table 3, the zinc concentration of the final liquid that passed through the anion exchange resin is 0.1 mg / L or less, all up to the liquid flow rate 306 BV (expressed as a multiple of the resin volume used (bed volume)). It can be seen that a highly pure nickel chloride aqueous solution is obtained.

(Example 2)
The nickel raw material is leached with chlorine gas, and the obtained nickel chloride aqueous solution is purified, and then the nickel chloride aqueous solution obtained in the wet purification process for obtaining electronickel by electrolysis is used to perform the first step and the second step. The process was performed. At this time, the effect of the step of contact treatment with activated carbon was verified.

Reagent grade zinc chloride is added to each of the two types of solutions, the purified solution obtained from the first step and the treatment solution after passing through the activated carbon tower, and the zinc concentration is adjusted. Adjusted to 0.003 g / L.
The solution was passed through a column packed with 200 mL of an anion exchange resin (Amberlite IRA400, manufactured by Organo Corporation) at a flow rate of SV2 to a flow rate of about 300 BV. Next, in order to elute the adsorbed zinc, water was passed at a fluid flow rate SV2 to a fluid flow rate of 5 BV. This series of adsorption / elution cycles was repeated 50 times.

  As a result, in the case where the step of contact treatment with activated carbon is not performed, the flow rate until the zinc concentration of the final solution is detected at 0.0001 g / L or more as the number of repetitions increases (hereinafter referred to as breakthrough BV). And the flow rate was reduced to about 70% of the breakthrough BV after the first flow through.

  On the other hand, when the step of contacting with activated carbon was used, the adsorption behavior was similar to that at the time of the first liquid passage after 50 repetitions, and a decrease in breakthrough BV could not be confirmed. That is, by performing the process of contacting the activated carbon, the decrease in breakthrough BV is suppressed in repeated use of the adsorption / elution cycle of the ion exchange process, so that the frequency of the elution operation is reduced and the drainage generated during elution is reduced. Treatment costs and wastewater treatment equipment costs are reduced.

It is used as a method for refining nickel chloride aqueous solution in the nickel refining field, and is particularly suitably used when it contains a large amount of impurity elements that form chlorine complexes.

Claims (2)

A method of purifying an aqueous nickel chloride solution containing an impurity element that forms zinc or another chlorine complex,
The nickel concentration of the aqueous nickel chloride solution is adjusted to 90 to 130 g / L , the oxidation-reduction potential is adjusted to 600 to 1200 mV with a silver / silver chloride electrode standard, and the pH is adjusted to 4.0 to 6.0, followed by oxidation neutralization, A first step of removing impurity elements, and a second step of subjecting the purified liquid obtained in the first step to ion exchange using an anion exchange resin and adsorbing and removing zinc. Purification method of nickel aqueous solution. Furthermore, prior to the second step, the method for purifying an aqueous nickel chloride solution according to claim 1, further comprising a step of contacting the purified liquid obtained in the first step with activated carbon.