JP6137058B2 - Purification method of cobalt chloride solution - Google Patents

Description

  The present invention relates to a method for purifying a cobalt chloride solution. More specifically, the present invention relates to a method for purifying a cobalt chloride solution for removing impurities from a cobalt chloride solution containing at least copper as an impurity.

  In the hydrometallurgical process for recovering nickel and cobalt from sulfides, the liquid purification process removes impurities from the resulting leachate by leaching nickel matte and nickel-cobalt mixed sulfide (MS) as raw materials. After that, electrolytic nickel and electrolytic cobalt are recovered in the electrolysis process.

  As shown in FIG. 1, the leachate obtained from the leaching step is sent to the cobalt solvent extraction step after removing copper in the cementation step and removing impurities such as iron and arsenic in the deironing step. In the cobalt solvent extraction step, nickel and cobalt are separated by solvent extraction to obtain a crude nickel chloride solution and a crude cobalt chloride solution. Impurities are further removed from the crude nickel chloride solution to obtain a high purity and sent to the nickel electrolysis process. In the nickel electrolysis process, electric nickel is produced by electrowinning. On the other hand, the cobalt chloride solution is further purified by removing impurities and sent to the cobalt electrolysis process. In the cobalt electrolysis process, electrolytic cobalt is produced by electrowinning.

  The liquid purification process of the crude cobalt chloride solution includes a plurality of detailed processes, including a copper removal process. In the copper removal step, impurities such as copper and lead are removed as sulfide starch by adding a sulfurizing agent to the crude cobalt chloride solution. Since the pH of the treatment liquid is lowered by the addition of the sulfiding agent, in order to prevent this, a pH adjuster is added to adjust the pH of the treatment liquid.

  Patent Documents 1 and 2 disclose that hydrogen sulfide is preferably used as a sulfiding agent. However, in order to add hydrogen sulfide to the cobalt chloride solution, it is necessary to vaporize the liquefied hydrogen sulfide sealed in the cylinder to generate hydrogen sulfide gas, which is then put into the liquid. When the used cylinder is switched, the supply of hydrogen sulfide gas is temporarily stopped. Accordingly, it is necessary to stop the operation of the copper removal process, and there is a problem that the operation rate is lowered. In addition, since the gas is handled, there is a problem that it is difficult to adjust the addition amount.

JP 2004-285368 A JP 2008-274382 A

  An object of this invention is to provide the liquid purification method of a cobalt chloride solution with a sufficient operation rate in view of the said situation.

According to the first aspect of the present invention, the cobalt chloride solution purification method comprises adding a sulfiding agent to a cobalt chloride solution containing at least copper as an impurity to remove the impurity as a sulfide starch. / L sodium hydrosulfide solution is used , and the sulfiding agent is added from the bottom of the reaction vessel supplied with the cobalt chloride solution .
The method for purifying a cobalt chloride solution according to a second invention is characterized in that, in the first invention, the amount of the sulfiding agent added is 4 to 10 times the molar equivalent of the amount of impurities contained in the cobalt chloride solution. .

According to the first invention, since the sodium hydrosulfide solution is used as the sulfiding agent, it is not necessary to switch the cylinder unlike the hydrogen sulfide gas, and the operating rate is improved. Moreover, since the density | concentration of a sodium hydrosulfide solution is 30-100 g / L, it can prevent that a local high pH area | region arises by contact with a cobalt chloride solution, and cobalt preferentially sulfides. Furthermore, since the sodium hydrosulfide solution is added from the bottom of the reaction vessel, the sulfurization reaction between hydrogen sulfide and impurities occurs while the hydrogen sulfide generated by the reaction between the sodium hydrosulfide solution and the cobalt chloride solution rises to the liquid level. As a result, the reaction efficiency is improved.
According to the second invention, since the addition amount of the sulfiding agent is 4 to 10 times the molar equivalent with respect to the impurity amount, the impurity can be sufficiently removed while reducing the coprecipitation amount of cobalt .

It is a whole process figure of a hydrometallurgical process. It is a detailed process drawing of a copper removal process. 4 is a table showing changes in impurity concentration and the like of a sodium chloride solution in Example 1.

Next, an embodiment of the present invention will be described with reference to the drawings.
The cobalt chloride solution purification method according to an embodiment of the present invention is applied to a nickel and cobalt hydrometallurgical process described below. The method for purifying a cobalt chloride solution according to the present invention is applicable to any process as long as it is a process for purifying a cobalt chloride solution containing at least copper as an impurity, regardless of the origin of the cobalt chloride solution.

  As shown in FIG. 1, in the nickel and cobalt hydrometallurgical process, first, the raw material nickel / cobalt mixed sulfide (MS: mixed sulfide) and nickel matte are leached with chlorine to obtain a leachate. The main component of the leachate is a nickel chloride solution, which contains impurities such as iron, copper and lead in addition to cobalt.

  The leachate obtained from the leaching step is sent to the cobalt solvent extraction step through a cementation step and a deironing step. In the cobalt solvent extraction step, cobalt contained in the leachate is separated by solvent extraction to obtain a nickel chloride solution and a cobalt chloride solution. For convenience of explanation, the nickel chloride solution and the cobalt chloride solution obtained from the cobalt solvent extraction step are referred to as a crude nickel chloride solution and a crude cobalt chloride solution, respectively. The crude cobalt chloride solution contains copper, lead and the like as impurities.

  In the crude cobalt chloride solution, impurities are removed in the liquid purification step to obtain a high purity cobalt chloride solution, which is sent to the cobalt electrolysis step. In the cobalt electrolysis process, electrolytic cobalt is produced by electrowinning.

  The liquid purification process of the crude cobalt chloride solution includes a plurality of detailed processes, including a copper removal process. As shown in FIG. 2, in the copper removal step, a sulfurizing agent is added to the crude cobalt chloride solution supplied to the reaction vessel to precipitate copper and lead as impurities as sulfide starch. In addition, since the pH of the treatment liquid is lowered by the addition of the sulfurizing agent, in order to prevent this, a pH adjuster is added to adjust the pH of the treatment liquid.

  As the pH adjusting agent, an alkaline or acidic pH adjusting agent is selected depending on the pH of the treatment liquid and / or the sulfurizing agent. The pH adjuster is not particularly limited, but an alkaline salt such as sodium hydroxide, calcium hydroxide, sodium carbonate, cobalt carbonate or the like can be used as the alkaline pH adjuster, and mineral such as hydrochloric acid or sulfuric acid can be used as the acidic pH adjuster. An acid can be used. Of these, cobalt carbonate is preferred because it can prevent other metals from being mixed into the cobalt chloride solution.

  The intermediate slurry discharged from the reaction tank is sent to a solid-liquid separation device such as a filter press device and separated into a high-purity cobalt chloride solution and sulfide starch. In this way, impurities can be removed as sulfide starch.

  The obtained high-purity cobalt chloride solution is supplied to the cobalt electrolysis step through other steps as necessary. Further, the sulfurized starch is repeated in the leaching step, and cobalt and the like contained in the sulfurized starch are recovered.

  This embodiment is characterized in that a sodium hydrosulfide solution having a concentration of 30 to 100 g / L is used as a sulfiding agent in the copper removal step of the above-described hydrometallurgical process. Moreover, the addition amount of the sulfurizing agent is characterized in that the molar equivalent is 4 to 10 times the amount of impurities contained in the cobalt chloride solution. Here, the amount of impurities means the amount of impurities such as copper and lead, for example, the sum of the amount of copper and the amount of lead.

  Since a liquid sodium hydrosulfide solution is used as the sulfiding agent, it is not necessary to switch the cylinder unlike the hydrogen sulfide gas. Therefore, it is not necessary to stop the operation every time the cylinder is switched, and the operating rate is improved.

Since water sulfate sodium solution is alkaline, concentration is too high localized high pH upon contact with cobalt chloride solution resulted. In that region, cobalt having a high concentration in the matrix component is preferentially sulfided rather than lead in which sulfide is stable in solution equilibrium. By setting the concentration of the sodium hydrosulfide solution to 100 g / L or less, it is possible to prevent the cobalt from being preferentially sulfided due to a local high pH region. Further, the concentration of water sulfate sodium solution by a 30 g / L or more, it is possible to suppress the concentration of cobalt chloride solution of Usumaru.

  If the addition amount of the sulfiding agent is less than 4 times the molar equivalent of the amount of impurities, the impurities cannot be sufficiently converted to sulfide starch. Moreover, when the addition amount of the sulfiding agent exceeds 10 times the molar equivalent of the impurity amount, the amount of cobalt co-precipitation increases and cobalt loss occurs. Therefore, if the addition amount of the sulfurizing agent is 4 to 10 times the molar equivalent of the impurity amount, the impurity can be sufficiently removed while reducing the coprecipitation amount of cobalt.

  Further, the present embodiment is characterized in that the sulfiding agent is added from the bottom of the reaction vessel supplied with the cobalt chloride solution. This can be realized, for example, by providing a sulfiding agent supply pipe in the reaction tank and providing a sulfiding agent outlet in the liquid.

  When sodium hydrosulfide solution is added as a sulfiding agent, hydrogen sulfide is generated by the reaction of sodium hydrosulfide and cobalt chloride solution. By adding the sodium hydrosulfide solution from the bottom of the reaction vessel, a sulfurization reaction between hydrogen sulfide and impurities occurs while the generated hydrogen sulfide bubbles rise to the liquid level. Therefore, the reaction efficiency is improved.

Next, examples will be described.
Example 1
In the copper removal step of the wet refining process, 15,000 L of cobalt chloride solution was supplied to the reaction vessel, and a sodium hydrosulfide solution having a concentration of 75 g / L was added from the bottom of the reaction vessel at a flow rate of 3.0 L / min. The flow rate of the sodium hydrosulfide solution corresponds to 0.26 times molar equivalent / min with respect to the sum of the amount of copper and the amount of lead contained in the cobalt chloride solution. Moreover, the pH adjuster was not added.

  The cobalt chloride solution before adding the sodium hydrosulfide solution had a copper concentration of 75 mg / L, a lead concentration of 4.6 mg / L, a pH of 1.85, and a redox potential (Ag / AgCl electrode standard) of 435 mV. Each time 20 L of sodium hydrosulfide solution was added, the cobalt chloride solution was sampled and the metal contained in the filtrate was analyzed. ICP emission analysis was used for metal analysis. The result is shown in FIG.

  From FIG. 3, when the addition amount of the sodium hydrosulfide solution with a concentration of 75 g / L is 4.6 times the molar equivalent or more of the copper amount and the lead amount contained in the cobalt chloride solution, the copper concentration of the filtrate is 1 mg / L. The lead concentration is 0.2 g / L, and it can be seen that a high-purity cobalt chloride solution with very few impurities can be obtained. Although a sufficient Co yield was obtained in the range shown, cobalt coprecipitation rapidly progressed and the cobalt yield deteriorated when the amount of sodium hydrosulfide solution added in the range not shown was 10.8 times the molar equivalent. The result was insufficient.

(Comparative Example 1)
4 L of cobalt chloride solution was heated to 40 ° C., and a sodium hydrosulfide solution having a concentration of 300 g / L was added at a flow rate of 2.0 mL / min. The amount of sodium hydrosulfide solution added was 7.5 times the molar equivalent of the sum of the amount of copper and the amount of lead contained in the cobalt chloride solution. After completion of the addition, the cobalt chloride solution was sampled and the metal contained in the filtrate was analyzed. ICP emission analysis was used for metal analysis.

  The cobalt chloride solution before adding the sodium hydrosulfide solution had a copper concentration of 110 mg / L, a lead concentration of 4.7 mg / L, and a pH of 1.85. After the addition of the sodium hydrosulfide solution, the filtrate had a copper concentration of less than 1 mg / L and a lead concentration of 0.5 g / L. That is, Comparative Example 1 had a higher lead concentration than Example 1.

  This is because the sodium hydrosulfide solution is alkaline, and when the concentration is high, a local high pH region is generated when it comes into contact with the cobalt chloride solution, and sulfide starch is generated in a solution equilibrium in that region. This is thought to be due to the fact that cobalt, which is a high concentration of matrix components, preferentially causes a sulfidation reaction, rather than easy lead.

Claims (2)

In removing the impurities as sulfide starch by adding a sulfiding agent to the cobalt chloride solution containing at least copper as impurities,
The concentration using the sodium hydrosulfide solution 30 to 100 g / L as a sulfurizing agent,
The method for purifying a cobalt chloride solution, wherein the sulfurizing agent is added from the bottom of a reaction vessel supplied with the cobalt chloride solution. The method for purifying a cobalt chloride solution according to claim 1, wherein the addition amount of the sulfurizing agent is 4 to 10 times the molar equivalent of the amount of impurities contained in the cobalt chloride solution.