JP2019143223A - Method for removing impurities from cobalt chloride solution - Google Patents

Abstract

To provide a method capable of stably removing impurities without adding excess additive in a solvent extraction treatment to a cobalt chloride solution including the impurities.SOLUTION: There is provided a method for removing impurities by conducting a solvent extraction treatment consisting of an extraction step S81, a cleaning step S82, and a reverse extraction step S83 preferably using di-(2-ethylhexyl)phosphonic acid as an extraction liquid on a cobalt chloride solution produced by for example a wet refining process of a nickel ore and containing at least Ca, Mn, Zn and Fe as impurities, a reverse extraction treatment condition of the reverse extraction step S83 is adjusted so that hydrochloric acid concentration of a liquid post reverse extraction drawn from the reverse extraction step S83 is 80 to 90 g/L.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for removing impurities from an aqueous cobalt chloride solution, and more particularly to a method for removing impurities from an aqueous cobalt chloride solution produced in a hydrometallurgical process.

  Since cobalt is excellent in wear resistance and heat resistance, it is widely used as a special steel in various fields such as aerospace, generators and special tools. Cobalt is also used as a magnetic material for small headphones and small motors by taking advantage of its strong magnetism. Furthermore, in addition to mobile information processing terminals such as personal computers and smartphones in recent years, the use of cobalt has also expanded as a raw material for positive electrode materials for lithium ion secondary batteries, for which demand is increasing for automobiles and power storage. Yes.

  Cobalt is often included as a mineral resource along with nickel and copper, and most of it is produced as a by-product of nickel smelting and copper smelting. Therefore, the separation of impurities such as nickel and copper is an important technical element in the production of cobalt. For example, Patent Document 1 discloses that a leachate obtained by chlorine leaching of a raw material containing nickel and cobalt is electrically processed by a cementation process, a deironing process, a cobalt solvent extraction process, and a cobalt electrolysis process. In the method for producing cobalt, a technique for removing impurities from a crude cobalt chloride aqueous solution containing impurities obtained in the cobalt solvent extraction step is disclosed. In the technique of Patent Document 1, an oxidizing agent and a neutralizing agent are added to a crude cobalt chloride aqueous solution to carry out an oxidation neutralization treatment, and then a sulfurating agent and a pH adjuster are added to remove copper, thereby removing impurities. To be removed.

  Patent Document 2 discloses that a crude cobalt chloride aqueous solution is subjected to solvent extraction of impurities and a part of cobalt using an organic phosphoric acid solvent extractant, and then the organic phase after the solvent extraction is adjusted to pH 1.5 to 1.5. Included in the crude cobalt chloride aqueous solution by back-extracting a part of the cobalt by bringing it into contact with an aqueous solution of 1.8, and further contacting the mineral acid aqueous solution and back-extracting impurities under the condition that the pH of the aqueous phase is 0.5 or lower. In addition to Mn as an impurity, a technique for removing Ca, Zn, and Fe is disclosed.

JP, 2006-014164, A JP 2017-190478 A

  However, in the technique of Patent Document 1, it is difficult to sufficiently remove Mn from the crude cobalt chloride aqueous solution, and when the composition of the raw material fluctuates, Mn as an impurity contained in the product may exceed the allowable value. . On the other hand, in the technique of Patent Document 2, an organic phase containing impurities is brought into contact with a mineral acid aqueous solution to transfer impurities to the aqueous phase and removed from the system, and the organic phase is controlled by keeping the pH of the aqueous phase low. Also aim to play. For this reason, the pH of the aqueous phase after back-extracting impurities tends to be controlled too low, and the consumption cost of the neutralizing agent used in the wastewater treatment process of the aqueous phase may be too high.

  That is, in the technique of Patent Document 2 described above, the upper limit value of pH 0.5 is defined with a focus on the removal of Mn from the crude cobalt chloride aqueous solution. In addition, the organic phase can be regenerated. Therefore, in actual operation, management of pH lower than 0.5 is management on the safe side. That is, in many cases, the pH of the aqueous phase is controlled at an excessively low pH so as not to cause a situation where the pH of the aqueous phase exceeds 0.5 for reasons such as fluctuations in the raw material composition. Furthermore, when the pH of the aqueous phase is controlled at the upper limit of 0.5 in the back extraction of impurities with an aqueous mineral acid solution, removal of impurities other than Mn may be insufficient, and the pH may be reduced due to problems such as the sensitivity of the pH meter. It was difficult to stably maintain at a low value of about 0.5.

  The present invention has been made in view of the problems of the conventional method for removing impurities from a cobalt chloride aqueous solution, and can be stably carried out without excessively adding an additive to the cobalt chloride aqueous solution containing impurities. An object of the present invention is to provide a method for removing impurities from an aqueous cobalt chloride solution, which can perform a solvent extraction process, and thus can reduce the cost of a wastewater treatment process.

  In order to achieve the above object, the method for removing impurities from an aqueous cobalt chloride solution according to the present invention comprises an extraction stage, a washing stage, and a back extraction for an aqueous cobalt chloride solution containing at least Ca, Mn, Zn, and Fe as impurities. A method of removing the impurities by performing a solvent extraction treatment comprising a stage, wherein the hydrochloric acid concentration in the solution after back extraction withdrawn from the back extraction stage is 80-90 g / L. It is characterized by adjusting the extraction processing conditions.

  According to the present invention, it is possible to stably perform a solvent extraction process without adding an additive excessively to an aqueous cobalt chloride solution containing impurities, and thus it is possible to suppress the cost of a wastewater treatment process. Become.

It is a process flow figure of the hydrometallurgical process to which the impurity removal method from the cobalt chloride aqueous solution of the present invention is applied suitably. It is a process flow figure of the cobalt liquid cleaning process of FIG. It is the graph which plotted the relationship between the impurity element in a water phase, and hydrochloric acid concentration when the cobalt chloride aqueous solution containing an impurity was mixed with the diluted hydrochloric acid aqueous solution which has various hydrochloric acid concentration in a beaker test, and the back extraction process was performed. It is a flowchart which shows one specific example of the adjustment method of the hydrochloric acid concentration of the liquid after back extraction discharged | emitted from the back extraction stage of FIG.

  First, a hydrometallurgical process to which the method for removing impurities from an aqueous cobalt chloride solution of the present invention is suitably applied will be described with reference to FIG. The hydrometallurgical process shown in FIG. 1 is a nickel and cobalt production process, also called MCLE (matt chlorine leaching electrowinning) process, and includes a chlorine leaching step S1, a pulverizing step S2, a cementation step S3, and a deironing step. It consists of S4, solvent extraction step S5, nickel purification step S6, nickel electrolysis step S7, cobalt purification step S8, and cobalt electrolysis step S9.

  First, in the chlorine leaching step S1, as a first raw material of the MCLE process, for example, nickel cobalt mixed sulfide (MS) obtained by hydrometallizing nickel oxide ore is added to an electrolytic waste liquid to form a slurry, which will be described later. While adding the cementation residue discharged | emitted from cementation process S3, chlorine gas is blown in and chlorine leaching of metal components, such as nickel, cobalt, copper, is performed. Thereby, the copper containing nickel chloride aqueous solution and the leaching residue containing the copper ion as a chlorine leaching liquid are produced | generated. The copper-containing nickel chloride aqueous solution generated in the chlorine leaching step S1 is sent to the cementation step S3, and the leaching residue is further processed because it contains sulfur as a main component, and is recovered as product sulfur.

  On the other hand, the nickel mat produced by dry smelting as the second raw material of the MCLE process is pulverized by a pulverizing apparatus such as a vibration mill in the pulverizing step S2, and then an electrolytic waste solution is added to form a mat slurry. This mat slurry is mixed with the copper-containing nickel chloride aqueous solution from the chlorine leaching step S1 in the cementation step S3. Thereby, the copper ion in the copper-containing nickel chloride aqueous solution is reduced by the nickel metal and nickel subsulfide in the nickel mat and fixed as copper sulfide. This fixed copper sulfide is solid-liquid separated as a cementation residue together with unreacted nickel, and then sent to the chlorine leaching step S1. Since the solution from which copper is removed by the immobilization in the cementation step S3 contains nickel and cobalt, the solution is sent to the iron removal step S4 as a cementation final solution.

  The above-mentioned cementation final solution is sent to the solvent extraction step S5 after iron as impurities contained in the cementation final solution is removed by a cleaning process such as oxidation neutralization in the deironation step S4. This solvent extraction step S5 comprises an extraction stage, a washing stage, and a back extraction stage. First, for example, TNOA (tri-n-octylamine) is used for the deironation-treated cementation final solution as an extraction start solution in the extraction stage. Amine-based extractants such as TIOA (tri-i-octylamine) and the like are mixed to perform a solvent extraction process to extract cobalt on the organic phase side and leave nickel in the extraction residual liquid on the aqueous phase side.

  The extraction residual liquid containing nickel extracted from the extraction stage is sent to the nickel washing step S6 as a crude nickel chloride aqueous solution, where, for example, deleading treatment or COB (Crowding Organic Bypass) -SX treatment is performed. Then, it is sent to nickel electrolysis process S7 as nickel chloride pure liquid, and electro nickel is produced by the electrowinning method. The chlorine gas generated from the nickel chloride solution on the anode side during this electrowinning is used as a chlorine leaching gas in the chlorine leaching step S1.

  On the other hand, the cobalt-containing organic phase extracted from the extraction stage is washed in a subsequent washing stage, and then mixed with a back extraction solution composed of a weakly acidic aqueous solution such as dilute hydrochloric acid in the back extraction stage. Back-extract cobalt to the water phase side. The back-extracted solution on the aqueous phase side containing cobalt obtained in this back extraction stage is sent to the cobalt washing step S8 as a crude cobalt chloride aqueous solution, and becomes a pure cobalt chloride solution by performing the washing treatment here. . This cobalt chloride pure solution is sent to the cobalt electrolysis step S9, and electric cobalt is produced by the electrowinning method.

  Next, the cobalt cleaning step S8 to which the impurity removal method from the cobalt chloride aqueous solution according to the embodiment of the present invention is applied will be described with reference to FIG. The cobalt cleaning step S8 includes an extraction stage S81, a cleaning stage S82, and a back extraction stage S83, similar to the solvent extraction step S5 described above. In FIG. 2, the dotted line indicates the flow on the organic phase side, and the solid line indicates the flow on the aqueous phase side. Each stage shows the organic phase on the upper side and the aqueous phase on the lower side, and the underlined substance moves from the organic phase indicated by the white arrow to the aqueous phase or from the aqueous phase to the organic phase.

  Specifically, each stage is described. First, in the extraction stage S81, an organic solvent is mixed with the crude cobalt chloride aqueous solution to perform a solvent extraction process, and Ca, Mg, Zn, Fe as impurities on the organic phase side, and a part thereof Co is extracted to leave Co, Cu and the like in the extraction residual liquid on the aqueous phase side. The organic solvent used for this solvent extraction is preferably one having a high impurity removal efficiency, for example, an organic phosphoric acid type solvent extractant such as di- (2-ethylhexyl) phosphonic acid.

  The extraction residual liquid containing Co, Cu, and the like is subjected to a copper removal treatment or the like in a post-process S84 as necessary, and then sent to the cobalt electrolysis process S9 as a cobalt chloride pure liquid. On the other hand, the organic phase containing impurities such as Ca and part of Co is washed by being mixed with a washing liquid such as dilute hydrochloric acid in the washing step S82, and the part of Co is recovered on the liquid side after washing. Is done. The partial Co recovered in the post-cleaning solution is processed in a cobalt chloride thin solution processing step S85.

  The organic phase containing impurities such as Ca washed in the washing stage S82 is then sent to the back extraction stage S83, where it is mixed with a dilute hydrochloric acid aqueous solution as a back extraction liquid to remove the impurities in the organic phase. Back extracted to the water phase side. The aqueous post-back extraction liquid containing impurities obtained in the back extraction stage S83 is sent to the waste water treatment step S86 to be subjected to waste water treatment such as general neutralization treatment and activated sludge treatment. In addition, the apparatus used for each stage such as the solvent extraction described above is simple to use a mixer setra having a structure in which a mixing tank equipped with a stirrer and a phase separation tank are combined by gravity sedimentation, and per unit installation area. Is preferable because of its high processing capacity.

  In the method for removing impurities from the aqueous cobalt chloride solution according to the embodiment of the present invention, as described above, an organic phase containing at least Ca, Mn, Zn, and Fe as impurities is back-extracted in a back extraction stage, and these impurities are extracted into an aqueous phase. When removing by distributing to the side, the hydrochloric acid concentration of the back-extracted solution is controlled within the range of 80 to 90 g / L by adjusting the hydrochloric acid concentration of the back-extracted solution. As a result, not only can the above-mentioned impurities be almost completely removed from the organic phase, but the amount of hydrochloric acid added in the back-extraction stage can be minimized, so that the post-back-extraction solution can be neutralized in the wastewater treatment process. The amount of drug used can be minimized.

  That is, in order to grasp the appropriate hydrochloric acid concentration in the aqueous phase in the back extraction stage, the reverse extraction liquid in which the hydrochloric acid concentration is variously mixed with the organic phase containing Ca, Mn, Zn, and Fe as impurities is mixed and reversed. When the extraction process was performed and the concentration of the impurity and the hydrochloric acid concentration in the obtained liquid after back extraction on the aqueous phase side were measured, the results shown in FIG. 3 were obtained. As can be seen from FIG. 3, when the hydrochloric acid concentration in the aqueous phase is about 20 to 30 g / L or more, the curves of Ca, Mn, and Zn are almost horizontal, so only the removal of these three types of impurities is possible. If so, a hydrochloric acid concentration in the aqueous phase of about 20-30 g / L is sufficient, but Fe is not back-extracted at this level of hydrochloric acid, and even if the hydrochloric acid concentration in the aqueous phase is increased to about 60 g / L. Can hardly be back-extracted.

  However, when the concentration of hydrochloric acid in the aqueous phase is set to 80 g / L or more, the curve for Fe is also horizontal. Therefore, the concentration of hydrochloric acid in the aqueous phase is set to 80 g / L or more to add all four types of Fe. It can be seen that impurities can be removed from the organic phase. The reason why the upper limit value of the hydrochloric acid concentration in the aqueous phase is 90 g / L is that, even if the chlorine concentration in the aqueous phase is increased above 90 g / L, the amount of back extraction of the impurities hardly increases. This is because the use amount of water and the neutralization cost in wastewater treatment increase, which is disadvantageous in cost.

  In addition, when operating in the back extraction stage under the condition that the pH of the aqueous phase reaches the upper limit of 0.5, this corresponds to the hydrochloric acid concentration of the aqueous phase being adjusted to about 12 g / L, as can be seen from FIG. Thus, when considering the removal of Mn, it is considered that back-extraction can be performed to some extent even with such a hydrochloric acid concentration. However, if the hydrochloric acid concentration in the aqueous phase is about 12 g / L, the back extraction of Zn or Ca is insufficient, and even Fe cannot be back extracted. Moreover, in actual operation, it is acidified as described above and is controlled on the safe side, so that the pH is controlled to be low, but it is difficult to control the pH with a value of almost zero or minus, so the aqueous phase hydrochloric acid is difficult to control. In some cases, the back extraction treatment is performed at a concentration higher than 90 g / L, for example, a concentration exceeding the hydrochloric acid concentration of 100 g / L.

  On the other hand, in the embodiment of the present invention, the hydrochloric acid concentration is controlled at 80 to 90 g / L, which is extremely higher than the above 12 g / L, in the back extraction stage, which is adjusted to pH (hydrogen ion concentration). In terms of conversion, control is performed within the range of -0.34 to -0.39. Such extremely low pH control is difficult to control using a general pH meter, but as described above, it is controlled by acid concentration (hydrochloric acid concentration) instead of pH, so back extraction is simple and accurate. Processing conditions can be adjusted.

  The method for adjusting the hydrochloric acid concentration in the aqueous phase of the back extraction stage is not particularly limited. For example, as shown in FIG. 4, a hydrochloric acid dilution tank 10 for preparing a back extract is provided, and the hydrochloric acid dilution tank 10 A measuring instrument for measuring the concentration of hydrochloric acid in the liquid after back-extracting the opening or opening / closing of the control valve 13 provided in the concentrated hydrochloric acid injection pipe 11 among the concentrated hydrochloric acid injection pipe 11 and the industrial water injection pipe 12 to be connected. It is preferable to automatically control with 14 output values. For example, when the hydrochloric acid concentration in the solution after back extraction measured by the measuring instrument 14 is lower than a predetermined concentration, the control valve 13 is opened from the closed state and concentrated hydrochloric acid is added to the hydrochloric acid dilution tank 10 to add the hydrochloric acid dilution tank. Since the hydrochloric acid concentration in the back-extracted solution can be increased by increasing the hydrochloric acid concentration in 10, the hydrochloric acid concentration in the solution after back-extraction can be increased to a predetermined concentration. On the other hand, when the concentration of hydrochloric acid in the solution after back extraction is higher than a predetermined concentration, the operation is reversed.

  In addition, you may measure the hydrochloric acid density | concentration of the back extraction liquid which flows through this extraction piping instead of the liquid after back extraction by providing said measuring device 14 in the extraction piping from the bottom part of the hydrochloric acid dilution tank 10. FIG. However, in this case, hydrochloric acid is consumed in the back extraction stage, for example, for regeneration of the organic solvent, so that the concentration of hydrochloric acid in the solution after back extraction is 80 to 90 g / L as described above by conducting a test or the like in advance. It is preferable to prescribe an appropriate hydrochloric acid concentration range in the extraction pipe of the hydrochloric acid dilution tank 10 that falls within the above range. Further, in place of or in addition to the control valve 13 of the concentrated hydrochloric acid injection pipe 11, the opening or opening / closing of a control valve (not shown) provided in the industrial water injection pipe 12 is measured. You may control based on the output value of 14.

  As mentioned above, although embodiment which applies the removal method of the impurity from the aqueous solution of cobalt chloride of the present invention to the cobalt cleaning process of the MCLE process has been described, the present invention is not limited to this, and impurities such as Ca, Mn, The present invention can be suitably applied as long as the organic phase containing Zn and Fe is treated with a back extract containing hydrochloric acid in the back extraction stage.

[Example]
Extraction stage and washing stage shown in FIG. 2 with respect to a crude cobalt chloride aqueous solution containing Ca, Mn, Zn and Fe as impurities generated by the MCLE process as shown in FIG. 1 and having a cobalt concentration of about 50 g / L These four types of impurities were removed by performing a solvent extraction process consisting of a back extraction stage. A mixer-settler type solvent extraction apparatus was used as the processing apparatus for each stage, and di- (2-ethylhexyl) phosphonic acid was used as the solvent. In addition, a commercially available 35% concentrated hydrochloric acid (about 400 g / L) diluted with industrial water is used as the back extract used in the back extraction stage, and hydrochloric acid of the back-extracted liquid discharged from the back extraction stage is used. The back extraction process was performed by adjusting the concentration to be about 85 g / L. An electromagnetic densitometer manufactured by Toa DKK Co., Ltd. was used for measuring the acid concentration of the back-extracted solution discharged from the back extraction stage.

  As a result, it was necessary to adjust the hydrochloric acid concentration of the back extract to around 120 g / L. Moreover, the Fe concentration in the liquid after back extraction on the water phase side discharged from the back extraction stage was 7 mg / L. When this commercially available caustic soda (flakes) was neutralized with an aqueous alkaline solution dissolved in industrial water, 93.2 g of caustic soda per liter of the back-extracted solution was required to neutralize to pH 7.

[Comparative Example 1]
The above procedure was carried out except that the back-extracted solution was controlled by the hydrochloric acid concentration instead of controlling the pH of the back-extracted solution to be 0.5 or less using a glass electrode type pH meter manufactured by TOA DK Corporation. The crude cobalt chloride aqueous solution was treated in the same manner as in the examples. As a result, it is difficult to stably control the pH, and it is often controlled near the upper limit of the pH meter. The hydrochloric acid concentration in the solution after back extraction at that time is about 60 g / L, and back extraction is performed. The Fe concentration in the post-solution was less than 1 mg / L, and the removal of Fe in the back extraction stage was insufficient. The caustic soda required for the neutralization treatment of the solution after back extraction was 65.8 g per liter of the solution after back extraction.

[Comparative Example 2]
In Comparative Example 1 above, the removal of the Fe concentration was insufficient, and therefore the pH was further controlled to lower the pH, which necessitated the preparation of a higher concentration of hydrochloric acid as the back extract. When the hydrochloric acid concentration of the solution after back extraction at this time was measured, it was about 180 g / L. As a result, the Fe concentration in the solution after back extraction was about 7 mg / L and was sufficiently removed, but the caustic soda required for the neutralization was 139.8 g per liter of solution after back extraction, which was 1 in comparison with Example 1. It took five times.

S1 Chlorine leaching process S2 Grinding process S3 Cementation process S4 Deironing process S5 Solvent extraction process S6 Nickel cleaning process S7 Nickel electrolysis process S8 Cobalt cleaning process S9 Cobalt electrolysis process 10 Hydrochloric acid dilution tank 11 Concentrated hydrochloric acid injection pipe 12 Industrial water Injection pipe 13 Control valve 14 Measuring instrument

Claims (3)

  A method of removing impurities by subjecting a cobalt chloride aqueous solution containing at least Ca, Mn, Zn, and Fe as impurities to a solvent extraction process comprising an extraction stage, a washing stage, and a back-extraction stage. A method for removing impurities from an aqueous cobalt chloride solution, wherein the back extraction treatment conditions of the back extraction stage are adjusted so that the hydrochloric acid concentration in the post-back extraction liquid extracted from the extraction stage is 80 to 90 g / L.   2. The method for removing impurities from an aqueous cobalt chloride solution according to claim 1, wherein the adjustment of the back extraction treatment condition is adjustment of a chlorine concentration of a back extraction solution supplied to the back extraction stage.   The flow rate regulating valve provided in the concentrated hydrochloric acid injection pipe among the concentrated hydrochloric acid injection pipe and the water injection pipe connected to the hydrochloric acid dilution tank for preparing the back extract is adjusted for the hydrochloric acid concentration of the back extract. The removal of impurities from the aqueous solution of cobalt chloride according to claim 2, wherein the opening / closing or the opening degree of the catalyst is controlled based on the output value of a measuring instrument for measuring the hydrochloric acid concentration of the back-extracted solution extracted from the back-extraction stage. Method.

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