WO2015146329A1

WO2015146329A1 - Copper removal method for aqueous nickel chloride solution

Info

Publication number: WO2015146329A1
Application number: PCT/JP2015/053689
Authority: WO
Inventors: 友彦横川; 中井　隆行; 柿本　稔; 高石　和幸
Original assignee: 住友金属鉱山株式会社
Priority date: 2014-03-26
Filing date: 2015-02-10
Publication date: 2015-10-01
Also published as: CA2943483C; JP2015183282A; CA2943483A1; NO20161679A1; JP6176491B2

Abstract

Provided is a copper removal method for an aqueous nickel chloride solution, the method able to prevent a reduction in organic solvent extraction capability and oil/water separation performance and further, when compared to prior art, the method does not increase chemical costs, does not degrade or decompose an extraction agent or increase the COD load of wastewater, and enables an aqueous nickel chloride solution having a high copper concentration to be treated. The copper removal method for an aqueous nickel chloride solution includes separating and recovering cobalt from an aqueous nickel chloride solution containing cobalt, copper, zinc, and iron using a solvent extraction method that uses for the organic phase, an organic solvent containing a tertiary amine as the extraction agent and an aromatic hydrocarbon as the diluent, wherein the method is characterized by comprising, in the following order, (1) an extraction step, (2) a reverse extraction step, and (3) a copper recovery step.

Description

Copper removal method of nickel chloride aqueous solution

The present invention separates and recovers cobalt from a cobalt chloride-containing aqueous solution of nickel chloride by solvent extraction using an organic solvent formed by diluting a tertiary amine of an extractant with an aromatic hydrocarbon as a diluent. It relates to the hydrometallurgical process of nickel and cobalt.

More specifically, copper containing cobalt is removed by removing the copper accumulated in the organic phase after the back extraction in which cobalt is desorbed from the organic phase from which cobalt is extracted, and the copper concentration in the organic phase is reduced. The present invention relates to a method for removing copper chloride aqueous solution from copper chloride aqueous solution which has low copper concentration as aqueous phase after back extraction from concentrated nickel chloride aqueous solution.

In smelting nickel and cobalt, for example, nickel sulfide obtained by melting nickel sulfide ore in a blast furnace, nickel sulfide obtained by adding sulfur to nickel oxide ore and melting in an electric furnace, etc. A nickel mat mainly composed of nickel sulfide such as Ni ₃ S ₂ obtained by a dry smelting process has been produced.

On the other hand, low pressure nickel leaching ore is subjected to pressure acid leaching (High Pressure Acid Leaking, commonly known as HPAL), and after removing impurities such as iron from the pressure acid leaching solution, wet sulfurization reaction, for example, sulfurization A mixed sulfide containing nickel and cobalt containing a sulfide as a main component such as NiS obtained by blowing hydrogen gas into a leaching solution containing nickel ions and cobalt ions (hereinafter referred to as mixed sulfide) Are also produced.

As a method of purifying nickel and cobalt using the above-mentioned nickel mat or mixed sulfide as a raw material, as described in, for example, Patent Document 1, the nickel mat or mixed sulfide is leached with chlorine gas and the leached nickel A method of commercializing ions and cobalt ions as electronickel and cobalt by electrowinning has been put to practical use.

The above method repulses mixed sulfide into aqueous chloride solution and then chlorine leaches nickel and cobalt into aqueous chloride solution by blowing chlorine gas into the slurry.
The nickel leaching solution containing the divalent copper chloro complex ion as an oxidizing agent is brought into contact with the pulverized nickel mat to carry out a substitution reaction between copper and nickel, thereby converting the nickel in the nickel mat into a liquid. Replace leaching.

Thereafter, impurities such as iron, lead, copper, zinc and the like are removed from the resulting substituted leaching final solution, and cobalt in the substituted leaching final solution is separated using a method such as solvent extraction, and then nickel is electrocollected. Is a method of producing electric nickel.
With respect to cobalt separated here, removal of further impurities is carried out by a treatment route different from nickel, and is commercialized as electrocobalt by electrowinning.

This method is simple and realizes efficient and economical production, such as reusing chlorine gas generated by electrowinning for leaching.
Furthermore, in the technology of Patent Document 1, copper contained in a small amount in the raw material such as nickel mat and mixed sulfide is an impurity in purifying nickel and cobalt, but in the above-mentioned chlorine leaching step and substitution leaching step It is used as an oxidant and is circulated between the chlorine leaching step and the displacement leaching step.

In the substitution leaching step, the nickel in the nickel mat is substitutionally leached into the liquid by carrying out the substitution reaction of divalent copper chloro complex ions with Ni ₃ S ₂ and Ni ⁰ (metallic nickel) in the nickel mat. The copper chloro complex ion becomes solid in the form of Cu ₂ S or Cu ⁰ (copper metal).

That is, in the displacement leaching step, dechlorination of the chlorine leachate is simultaneously carried out, and the copper concentration in the displacement leached final solution becomes 0.02 g / L or less. The copper introduced from the raw material gradually accumulates in the chlorine leaching step and the displacement leaching step while circulating between the chlorine leaching step and the displacement leaching step, so that the copper concentration in the chlorine leachate is 10 to 60 g / L. In order to maintain the proper value within the range, copper is extracted as copper powder out of the system, for example, by dechlorination of a chlorine leaching solution to achieve copper balance.

By the way, in the hydrometallurgical process of nickel, the separation of nickel and cobalt contained in the acidic aqueous solution is the most important technical element.
For example, a method of separating cobalt as a trivalent hydroxide by adding chlorine gas as an oxidizing agent and a nickel carbonate slurry as a neutralizing agent to an aqueous solution of nickel containing cobalt has also been carried out. In order to completely remove cobalt in solids as solid, nickel, which is about 3 times the weight ratio of cobalt, also produces trivalent hydroxide, and because the separation between nickel and cobalt is poor, it is efficient and economical. It was not a good idea.

Therefore, currently, the separation of nickel and cobalt contained in an acidic aqueous solution is mainly performed by solvent extraction using various organic extractants.
In the solvent extraction method for separating nickel and cobalt, phosphoric acid ester acidic extractant such as D2EHPA (Di- (2-ethylhexyl) phosphoric acid) as an organic extractant, amine such as TNOA (Tri-n-octylamine), etc. A system extractant is used.

Both the phosphoric acid ester-based acidic extractant and the amine-based extractant have excellent nickel and cobalt separation performance, but generally, when the anion is a sulfate ion, the phosphoric acid ester-based acidic extractant is When the anion is chloride ion, an amine extractant is used.

In the case of a chloride aqueous solution having a chloride ion concentration of 200 g / L or more, in which the chloride ion concentration in the aqueous solution is sufficiently high, cobalt forms a chloro complex ion but nickel does not form a chloro complex ion. The agent has a higher cobalt and nickel separation factor compared to the phosphoric acid ester acid extractant.

In addition, in the case of a phosphoric acid ester-based acidic extractant, protons are released from the extractant by extraction of metal ions, which requires a neutralizing agent cost, and in addition, a clad is often generated due to pH fluctuation.
The above-mentioned clad is a solid such as metal hydroxide and is retained and accumulated between the organic phase and the aqueous phase in the oil-water separator, so that oil-water separation which is an important technical element of solvent extraction is largely inhibited.

The method of separating cobalt from an aqueous solution of nickel chloride containing cobalt and other impurity elements with an amine-based extractant is a technique as described below in a solvent extraction step comprising an extraction stage, a washing stage and a back extraction stage. Based on

It is more preferable to use a tertiary amine (R ₃ N) as the extractant than a primary amine (RNH ₂ ) or a secondary amine (R ₂ NH) (R is any saturated or unsaturated hydrocarbon group Represents
The reason is that tertiary amines are more polar and have higher reactivity, and also have lower solubility in water.
This tertiary amine is added with hydrochloric acid and activated to retain the extraction ability of metal chloro complex ion and has excellent separation characteristics of nickel and cobalt.

In the extraction stage, metal species forming chloro complex ions such as Co, Cu, Zn, and Fe are extracted into the organic phase, and an amine supporting chloro complex ions of metal elements is generated. In addition, since nickel does not form a chloro complex ion, it remains in the extraction residual liquid and is isolate | separated.
Therefore, when an aqueous solution of nickel chloride is more likely to form a chloro complex ion than cobalt, that is, contains a metal having a high stability of the chloro complex ion, such as a copper, zinc or iron chloro complex ion, Metals are also extracted.

Although the washing stage is installed if necessary, in the washing stage, entrainment in the organic phase after extraction, that is, when there are many impurities contained in fine water droplets suspended in the organic phase, etc. The impurities are removed by dilution and removal with wash water.

Next, in the back extraction stage, cobalt can be desorbed into the aqueous phase by bringing the washed organic phase, that is, the amine supporting the chloro complex ion of cobalt, into contact with a weakly acidic aqueous solution.
Here, the organic phase from which cobalt has been back-extracted, i.e., the regenerated extractant, is again returned to the extraction stage for recycling and extraction, washing and back-extraction will be repeated.

However, metals that are more easily supported by amines as chloro complex ions than cobalt, such as copper, zinc, and iron, are less likely to be eliminated under relatively weak back-extraction conditions for removing cobalt, and thus, in the solvent extraction step When the amine extractant is used cyclically, copper, zinc, iron and the like gradually accumulate in the extractant.
When such accumulation of metal proceeds, the amino group to be contributed to the extraction reaction is occupied by the accumulated metal, leading to a drastic decline in the extraction ability of the extractant. In addition, since the viscosity of the extractant is increased, the oil-water separation performance is also reduced.

To solve this problem, for example, in order to separate and remove these metals from an amine-based extractant carrying a chloro complex ion such as copper, zinc, or iron, a scrubbing stage is provided to regenerate the extractant. It has been done.
For example, in Patent Document 2, a part of the organic phase after back extraction is extracted, and zinc contained as an impurity is removed by neutralization treatment, and then the extractant is activated, and the organic phase after activation is chlorinated. A method is described for contacting with the aqueous phase after back extraction which is a cobalt aqueous solution.

The method of removing copper, zinc, iron, etc. contained in the amine-based extractant after this back extraction by neutralization treatment is based on the reaction accompanied by the formation of a precipitate, and therefore includes an organic phase, an aqueous phase and a precipitate. The mixture needs to be solid-liquid separated by filtration equipment such as a filter press, which not only has poor filterability, handleability and workability, but also has a security problem of filtering hazardous materials by mechanical equipment, which is a preferable method. It was hard to say.
Furthermore, the organic phase adheres to the precipitate, leading to loss of the expensive extractant, resulting in an increase in the cost of the extractant.
Also, disposal of the mixture of extracted oil and heavy metal requires a great deal of technology and cost to prevent environmental problems.

Then, the improved method shown by patent document 3 is proposed and implemented as a means to solve these problems.
In this method, the organic phase after back extraction is alkali neutralized, and from the mixture containing the organic phase after aqueous alkali neutralization, the aqueous phase and the precipitate, the organic phase not containing the precipitate is removed by sedimentation and the aqueous phase Acid dissolve the mixture containing the precipitate and the remainder of the organic phase.

The aqueous phase containing copper, zinc, iron and the like after acid dissolution is sent to the next treatment step such as, for example, a waste water treatment step, and the organic phase containing copper, zinc, iron and the like is repeated in the scrubbing stage.
By this method, the handling of the precipitate mixed with the organic phase and the aqueous phase was completely lost.

The scrubbing methods of Patent Document 2 and Patent Document 3 require an alkali for neutralization and a hydrochloric acid for activation. Then, the method which does not use these agents is also proposed by patent document 4, for example.
This is to wash the organic phase after back extraction with water or an aqueous solution with a chloride ion concentration of 0 to 5 g / L so that the (organic phase / aqueous phase) ratio is 1 to 10, Compared to the methods of Document 2 and Patent Document 3, the equipment is simple and cost-effective.

However, this method is a technology that can be realized only under a narrow range of conditions such as extraction iron of 25 mg / L or less and zinc of 0.1 mg / L or less, and the target impurity metal is It is iron or zinc.

By the way, in the process described in Patent Document 1, in which nickel mat and mixed sulfide are leached with chlorine gas and the leached nickel ion and cobalt ion are produced as electronickel and cobalt by electrowinning, nickel is used. Copper contained in trace amounts in raw materials such as mats and mixed sulfides is used as an oxidizing agent in the chlorine leaching step and the displacement leaching step, and is circulated in the chlorine leaching step and the displacement leaching step.
Therefore, it is necessary to maintain the copper concentration in the chlorine leachate at an appropriate value within the range of 10 to 60 g / L.

On the other hand, since copper is an impurity in purifying nickel and cobalt, the copper concentration in the displacement leaching solution needs to be 0.02 g / L or less.
In order to lower the copper concentration of this substituted leachate lower than the copper concentration in the chlorine leachate, a nickel mat containing Ni ⁰ or Ni ₃ S ₂ having a stronger reducing power than NiS contained in the mixed sulfide is required. .

However, when mixed sulfides are further treated to increase production of nickel and cobalt, there will also be a situation where the nickel mats will be relatively short, so a technology that can respond flexibly to changes in the raw material composition ratio as much as possible is needed. It was
Specifically, removal of copper which can be coped with even if the copper concentration in the displacement leaching final solution, that is, the copper concentration in the extraction starting solution in the solvent extraction step increases from 0.02 g / L to 0.2 g / L It was necessary to establish the technology.

Although copper accumulated in the extractant can be removed by the method of alkali neutralization in the scrubbing stage as a solution to the above problems, alkali for neutralization and hydrochloric acid for activation are required, resulting in cost increase. Not only that, the scrubbing ratio of the organic phase after the back extraction is increased.

In addition, the strong alkali degrades and decomposes the organic solvent, which lowers the extraction ability of the amine, and increases the concentration of the decomposed organic substance in the aqueous phase after scrubbing, resulting in various problems such as an increase in COD load on the wastewater. Is triggered.

Furthermore, since the above alkaline neutralization method is mainly intended to remove zinc, it is necessary to establish a technique for selectively removing copper accumulated in an amine-based extractant independently of the method. The

JP, 2012-026027, A Japanese Patent Application Laid-Open No. 60-121236 JP, 2010-196162, A JP, 2010-196122, A

The present invention separates and recovers cobalt from an aqueous solution of nickel chloride by solvent extraction with an organic solvent formed using a tertiary amine as an extractant and using an aromatic hydrocarbon as a diluent thereof, as well as copper, zinc and iron. By selectively removing copper accumulated in the extractant, it is possible to prevent the deterioration of the extraction ability of the organic solvent and the oil-water separation property, and further, compared with the prior art, To provide a copper chloride aqueous solution decoppering method capable of processing an aqueous nickel chloride solution having a high copper concentration without degrading the decomposition agent and increasing the COD load of the drainage without increasing the cost and increasing the COD load of the wastewater. With the goal.

In order to achieve the above object, when the chloride ion concentration in the aqueous phase is low, the present inventors tend to transfer copper accumulated in the extractant after back extraction into the aqueous phase as compared to zinc and iron. Focusing on the chloride ion concentration of the aqueous phase to be mixed and brought into contact with the organic phase after the back extraction, that is, the extraction conditions such as pH of dilute hydrochloric acid and O / A ratio, the result after the back extraction It is found that copper accumulated in the extractant after the back extraction can be selectively removed by mixing and contacting water or dilute hydrochloric acid having a pH of 1 or more with the organic phase so that the O / A ratio is 1.5 or less. The present invention has been completed.

That is, the first invention in the method for copper removal of an aqueous solution of nickel chloride of the present invention uses a solvent extraction method using an organic solvent containing a tertiary amine as an extractant and an aromatic hydrocarbon as a diluent in an organic phase A process for separating and recovering cobalt from an aqueous solution of nickel chloride containing cobalt, copper, zinc and iron, and removing copper, zinc and iron, characterized in that it comprises the following steps (1) to (3) in order: Copper removal method of nickel chloride aqueous solution.

(1) Extract cobalt, copper, zinc, iron into the organic phase from the aqueous solution of nickel chloride containing cobalt, copper, zinc, iron to form an organic phase containing cobalt, copper, zinc, iron, cobalt Extraction step to obtain an aqueous solution of nickel chloride from which copper, zinc and iron have been removed.
(2) Cobalt in the organic phase is desorbed from the organic phase by bringing the weakly acidic aqueous solution into contact with the organic phase containing the cobalt, copper, zinc and iron obtained in the step (1). A back extraction step to obtain an aqueous phase of a cobalt chloride aqueous solution and an organic phase containing copper, zinc and iron after back extraction.
(3) Water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact with the organic phase after the back extraction, and the copper in the organic phase is back extracted to the aqueous phase to recover the copper, and zinc is removed The copper recovery step, wherein the iron-containing organic phase is used as the organic solvent in the step (1).

Next, according to the second invention of the present invention, the nickel concentration in the aqueous solution of nickel chloride containing cobalt, copper, zinc, iron in the extraction step (1) of the first invention is 170 to 210 g / L, and the cobalt concentration is The copper in the organic phase containing cobalt, copper, zinc, and iron obtained in the step (1) with 2 to 10 g / L and a copper concentration of 0.01 to 0.2 g / L, and the copper concentration is 0 Removal of copper to a concentration of 0.3 g / L or less in the aqueous solution of cobalt chloride obtained in the back extraction step of (2) by removing the solution to 4 g / L or less It is a method.

A third invention of the present invention is the removal of the aqueous solution of nickel chloride characterized in that the volume ratio of the organic relative aqueous phase in the copper recovery step of (3) of the first and second inventions is 1.5 or less. It is a copper method.

A fourth invention of the present invention is nickel chloride characterized in that the tertiary amine in the first to third inventions is tri-normal-octylamine (TNOA) or tri-iso-octylamine (TIOA). It is a method of removing copper from an aqueous solution.

According to the present invention, by selectively removing the copper accumulated in the extractant, it is possible to prevent the decrease in the extraction ability of the organic solvent and the oil-water separation property, and copper in the extraction solution which is an aqueous solution of nickel chloride. Even if the concentration increases from 0.02 g / L to 0.2 g / L, the chloride obtained in the back-extraction step is removed by removing the copper in the organic phase until the copper concentration is 0.4 g / L or less. The copper concentration in the cobalt aqueous solution can be 0.3 g / L or less.

Furthermore, as compared with the prior art, since the alkali for neutralization and the hydrochloric acid for activation are not required, the drug cost is not increased, the extractant is degraded and decomposed, and the COD load of the drainage is increased. I have nothing to do.

The present invention is a simple method in which water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact with the organic phase after the back extraction, so it can be coped with simple equipment modification, and low cost and low environmental load and efficient. Operation can be realized.
In addition to the above effects, it is possible to increase the production of electronickel and cobalt by increasing the raw material processing ratio of the mixed sulfide to the nickel mat and increasing the mixed sulfide.

1 is a schematic flow sheet of a nickel and cobalt smelting process including the present invention. It is a schematic flow sheet of the solvent extraction process in the copper removal method of this invention. It is the figure which showed the relationship between the copper concentration in an organic phase, and the copper concentration in a water phase. It shows the relationship between the chloride ion concentration in the aqueous phase and the distribution ratio into the organic phase for copper, zinc and iron.

Hereinafter, the copper removal method of the aqueous solution of nickel chloride of the present invention will be described in detail.
The method of copper removal from aqueous solution of nickel chloride of the present invention uses a tertiary amine as an extractant and an aromatic hydrocarbon as a diluent for diluting the extractant from an aqueous solution of nickel chloride containing cobalt, copper, zinc and iron. The solvent is used to separate and recover cobalt and remove copper, zinc and iron by solvent extraction using the organic solvent thus formed, and is characterized by including the following steps (1) to (3) .

(1) Extraction process An organic phase is formed by extracting cobalt, copper, zinc and iron from an aqueous solution of nickel chloride containing cobalt, copper, zinc and iron used in the aqueous phase to remove cobalt, copper, zinc and iron. Extraction step to obtain an aqueous solution of nickel chloride (aqueous phase).
(2) Reverse extraction step A reverse extraction step of obtaining cobalt chloride aqueous solution by removing cobalt from the organic phase from which cobalt, copper, zinc and iron are extracted by the weakly acidic aqueous solution used for the aqueous phase.
(3) Copper recovery step Water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact with the organic phase after the back extraction from which cobalt has been eliminated, and copper in the organic phase is backextracted into the aqueous phase, The copper recovery step, wherein the organic phase after removing copper is returned to the extraction step (1).

1. Nickel and Cobalt Smelting Process A schematic flow sheet of the nickel and cobalt smelting process including the present invention is shown in FIG.
The present invention relates to scrubbing of the organic phase after back extraction in the solvent extraction step (step shown as A in FIG. 1) in the overall steps of the nickel and cobalt smelting process, but the raw material processing ratio, See Figure 1, as it is a technology to achieve global optimization with respect to key elements of the nickel and cobalt smelting process, such as chlorine leaching, displacement leaching (cementation), purification to solvent extraction, solvent extraction, etc. The main elements will be described in detail.

(1) Raw materials The main raw materials are nickel mat and mixed sulfide.
Nickel matte refers to nickel sulfide obtained by melting nickel sulfide ore in a blast furnace, nickel sulfide obtained by adding sulfur to nickel oxide ore and melting in an electric furnace, etc. Refers to a nickel sulfide.

The main components of this nickel mat are Ni ₃ S ₂ and Ni ⁰ (metallic nickel), and the approximate chemical composition is 65 to 80% by weight of Ni, about 1% by weight of Co, and 0.1 to Cu It is 4% by weight, 0.1 to 5% by weight of Fe, and 20 to 25% by weight of S.

Compared with nickel mats made from nickel oxide ore, nickel mats made from nickel sulfide ore are characterized by having a high content of impurities, and the main copper input sources for nickel and cobalt smelting processes are , A nickel mat using nickel sulfide ore as a raw material.
Therefore, the amount of input of copper fluctuates significantly depending on the amount of nickel matte processed using this nickel sulfide ore.

On the other hand, mixed sulfide refers to hydrogen sulfide gas, for example, by wet sulfidation reaction after pressure acid leaching of low nickel grade nickel oxide ore and removal of impurities such as iron from the pressure acid leach solution. It refers to a mixed sulfide containing nickel and cobalt obtained by blowing into a leach solution containing nickel ions and cobalt ions.

The main components of this mixed sulfide are NiS and CoS, and the approximate chemical composition thereof is 55 to 60% by weight of Ni, 3 to 6% by weight of Co, less than 0.1% by weight of Cu, and 0 1 to 1% by weight, S is 30 to 35% by weight.

(2) Chlorine leaching After mixed sulfide and cementation residue to be described later are repulped into aqueous chloride solution, nickel and cobalt in mixed sulfide and nickel in cementation residue are obtained by blowing chlorine gas into the slurry. And copper are leached out into aqueous chloride solution.

In this process, the chloro complex ion of divalent copper acts as a direct leaching agent for dissolving metals in mixed sulfides and cementation residues, and chlorine gas converts copper monovalent ion to divalent ion. It indirectly participates in the leaching reaction by oxidation.
Therefore, a certain amount of copper is essential for the chlorine leaching reaction, and it is important to maintain the copper concentration in the chlorine leaching solution within the range of 10 to 60 g / L.
The main chlorine leaching reaction formulas are shown in the following formulas (1) to (4).

The chlorine leaching reaction conditions are such that the oxidation reduction potential of the aqueous solution of nickel chloride during the reaction is 480 to 550 mV (based on Ag / AgCl electrode), and the temperature is 105 to 115 ° C.

(3) Substitution leaching (cementation)
The displacement leaching step consists of two stages, a first displacement leaching step ("displacement leaching 1" in FIG. 1) and a second displacement leaching step ("displacement leaching 2" in FIG. 1).
Nickel and cobalt in the mixed sulfide are leached in the first displacement leaching step using the oxidizing power of the divalent copper chloro complex ion contained in the chlorine leachate.
In the substituted leachate obtained in the first substitutional leaching step, the divalent copper chloro complex ion is reduced to a monovalent copper chloro complex ion.

Next, in the second substitution leaching step, the substitution leaching solution obtained in the first substitution leaching step is brought into contact with the nickel mat to cause a cementation reaction between copper ions in the substitution leaching solution and nickel in the nickel mat. To be done.
In this cementation reaction, solid nickel is eluted to become nickel ions, and copper ions in a solution that is electrochemically equivalent to the eluted nickel become solid, and therefore the displacement leaching step is carried out by the copper contained in the chlorine leachate. It can be said that this is a decoppering step to remove

The copper ion in the displacement leaching solution becomes a solid in the form of Cu ₂ S or Cu metal, so the copper concentration in the displacement leaching final solution obtained in the second displacement leaching step is 0.02 g / L or less .

In order to reduce the copper concentration of this substitution leaching final solution, a nickel mat containing Ni ⁰ (metallic nickel) having stronger reducing power than NiS contained in the mixed sulfide or Ni ₃ S ₂ is required.

Cementation residue, including mixed sulfide and insoluble residue of nickel mat and solid containing copper obtained by cementation reaction, is solid-liquid separated from the displacement leaching final solution obtained in the second displacement leaching step Then, it is sent to the chlorine leaching process.
The main substitutional leaching reaction formulas are shown in the following formulas (5) to (7).

The conditions for the displacement leaching reaction are 50 to 300 mV (based on Ag / AgCl electrode) of the redox potential of the aqueous solution of nickel chloride at the time of reaction, and the temperature is 70 to 100 ° C.

The amount of copper to be removed from the solution in the second displacement leaching step is determined by the product of the amount of chlorine leachate and the concentration of copper in the chlorine leachate.
The amount of chlorine leachate is determined by the amount of mixed sulfide to be treated in the chlorine leaching step and the first displacement leaching step.
The concentration of copper in the chlorine leachate is a constant value because it is maintained at an appropriate value within the range of 10 to 60 g / L to continue the optimum chlorine leaching operation.

Therefore, if the treatment ratio of the nickel mat to the mixed sulfide decreases, there is a concern that the nickel mat may be insufficient for the amount of copper to be removed, in which case the displacement leaching final solution obtained in the second displacement leaching step The copper concentration inside will rise.

(4) Pure solution The substitution leaching final solution (sement cement final solution) is sent to the pure solution process. The liquid purification process is composed of a deironing process, a solvent extraction process, a lead removal process, and a dezincification process.

In the iron removal step, substitution leaching is carried out by adding chlorine gas as an oxidizing agent and a nickel carbonate slurry as a neutralizing agent to the substitution leaching final solution to form a precipitate containing ferric hydroxide as a main component. A treatment is performed to reduce the iron concentration in the final solution from 1 to 2 g / L to 15 mg / L or less.
Since the pH of the aqueous solution in this deironization step is about 2.0 to 2.5, copper hydroxide is not generated in this step.
Furthermore, since copper is not removed in this deironing step, when the copper concentration in the substitution leaching final solution increases, the copper concentration in the extraction starting solution subjected to the next liquid purification step (solvent extraction) increases. become.

Although details will be described later, in the solvent extraction step, the nickel concentration is 170 to 210 g / L, the cobalt concentration is 2 to 10 g / L, the copper concentration is 0.02 g / L or less, and the zinc concentration is 0.01 to 0.03 g / L. Treatment of transferring cobalt, copper, zinc, iron from aqueous phase to organic phase by mixing and contacting TNOA, which is an amine extractant, with demineralized iron final solution having an iron concentration of 15 mg / L or less .

In the lead removal step, chlorine gas as an oxidant and a nickel carbonate slurry as a neutralizer are added in the same manner as the iron removal step to remove lead in the nickel chloride solution after solvent extraction as lead oxide.
Since the pH of the extraction residue in the lead removal step is 4 to 5, part of nickel also forms a precipitate as a trivalent hydroxide.

In the dezincification step, about 0.1 mg / L of a chloro complex ion of zinc remaining in a trace amount in the deleaded final solution after deleading is adsorbed and removed by a weakly basic anion exchange resin.

2. Solvent Extraction Step Next, the solvent extraction step constituting the copper removal method according to the present invention and constituting a part of the liquid purification step of the above (4) will be described in detail.

(1) Configuration of Solvent Extraction Step A schematic flow sheet of the solvent extraction step according to the present invention is shown in FIG. This flow sheet also represents the flow of the copper removal method according to the present invention.
The solvent extraction is adopted in a countercurrent multistage system, and comprises an extraction stage, a washing stage, a back extraction stage, and a copper recovery stage.
Using the mixer-settler type extractor, in the embodiment used to explain the present invention, the extraction stage comprises 3 stages, the washing stage also 3 stages, the back extraction stage 3 stages, and the copper recovery stage 1 stage ing.
In order to remove zinc and iron in the organic phase after back extraction in the back extraction stage, it is preferable to provide a dezincification stage in parallel or in series with the copper recovery stage.

That is, according to the copper concentration of the extraction starting solution, a predetermined amount of the back-extracted organic phase is extracted, water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact, and copper in the organic phase is back-extracted into the aqueous phase. Depending on the recovery stage and the degree of concentration of zinc or iron in the organic phase after back extraction, a predetermined amount of the organic phase after back extraction is extracted and alkali neutralized to remove zinc and iron in the organic phase If the dezincification stages are operated independently of one another, copper, zinc and iron in the organic phase can be efficiently removed.

Since zinc and iron are input from the mixed sulfide, the zinc concentration of the extraction starting solution depends on the zinc content in the mixed sulfide and the amount of mixed sulfide processed.
The iron concentration of the extraction start solution is always constant because it is removed in the deferrous step.
On the other hand, the copper concentration of the extraction start solution is determined by the treatment ratio of the nickel mat to the mixed sulfide.

That is, since the zinc concentration and the copper concentration of the extraction start solution independently fluctuate, and the fluctuation range of the copper concentration is particularly large, it is better to operate the removal of zinc and copper in the organic phase independently of each other. It is efficient.

In addition, water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact with the organic phase a after serial extraction, that is, back extraction, and copper in the organic phase a is back extracted to the aqueous phase, and then copper is recovered. Even if the organic phase b is alkali-neutralized to remove zinc and iron in the organic phase, the amount of alkali used in the dezincification stage can be reduced because of the balance of copper content, resulting in cost reduction.

(2) Extractant and Reaction The extractant uses a tertiary amine, preferably tri-normal-octylamine (TNOA) or tri-iso-octylamine (TIOA).
An aromatic hydrocarbon is used as a diluent for the extractant.
In order to adjust the viscosity of the organic phase, the extractant concentration in the organic phase (extractant and diluent) is set to 20 to 40% by volume.

Tertiary amines have the ability to extract metal chloro complex ions as shown in formulas (9) and (9 ') by addition of hydrochloric acid and activation according to formula (8) below, and are excellent. Have separation characteristics of nickel and cobalt.

M in the above formula (9) represents a metal species that forms a chloro complex ion such as Co, Cu, Zn, etc., but since the form of the chloro complex ion differs depending on the valence of the metal ion, for example, Fe (trivalent) In the case of, following formula (9 ') follows.
In addition, ":" in Formula (8), Formula (9), and Formula (9 ') represents the noncovalent electron pair of a nitrogen atom.

In the extraction stage, metal species forming a chloro complex ion such as Co, Cu, Zn, Fe, etc. are extracted into the organic phase by the reaction represented by the formula (9) or the formula (9 ′), and An amine carrying complex ions is formed. In addition, since nickel does not form a chloro complex ion, it remains in the extraction residual liquid and is isolate | separated.
Therefore, when an aqueous solution of nickel chloride is more likely to form a chloro complex ion than cobalt, that is, contains a metal having a high stability of the chloro complex ion, such as a copper, zinc or iron chloro complex ion, Metals are also extracted.

On the other hand, in the reverse extraction stage, the organic phase after washing, that is, the amine carrying a chloro complex ion of cobalt is brought into contact with a weakly acidic aqueous solution, according to the following formula (10) which is a reverse reaction of formula (9). , Cobalt can be released into the aqueous phase.

3. Dechlorination by solvent extraction The main function of solvent extraction is to extract and separate cobalt from the initial solution (mixed solution of nickel chloride and cobalt chloride) firstly, but as a further function, the organic phase after back extraction If copper can be selectively desorbed from it, it can also play a role as a step of removing copper in the initial solution.

Therefore, copper removal from chlorine leachate in the nickel and cobalt smelting process is basically carried out in the substitution leaching (cementation) step, but the copper concentration in the substitution leaching final solution is large due to lack of nickel mat etc. If it fluctuates or rises, decoppering by solvent extraction is effective.

It is a first feature of the present invention to utilize this solvent extraction as a copper removal step.
In the extraction stage, even if the copper concentration in the extraction start solution is as high as 0.2 g / L, almost all copper ions can be extracted into the organic phase.
This is because the concentration of chloride ion in the initial solution is as high as 200 to 250 g / L and copper forms a stable chloro complex ion.

On the other hand, in the back extraction stage where cobalt is recovered as a cobalt chloride aqueous solution, the chloride ion concentration is lower than that of the extraction stage, and is 70 to 100 g / L.
Therefore, at a chloride ion concentration of 70 to 100 g / L, copper chloro complex ions in the organic phase become unstable, and part of the copper is back-extracted into the aqueous phase.
Since the copper concentration in the aqueous phase is in proportion to the copper concentration in the organic phase, when the copper concentration in the organic phase is increased, the copper concentration in the aqueous solution of cobalt chloride is increased.
When the concentration of copper in the aqueous solution of cobalt chloride increases, the load (de-copper removal) of the subsequent purification of aqueous solution of cobalt chloride increases, but there is also the possibility of increasing the copper content of the product electrocobalt.

FIG. 3 shows the relationship between the copper concentration in the organic phase and the copper concentration in the aqueous phase in the back extraction stage.
The data in FIG. 3 shows that 20% by volume or 30% by volume of tri-norm-octylamine (TNOA) as an extractant in a countercurrent multistage solvent extraction process of three extraction stages, three washing stages and three back extraction stages. It is operation data at the time of using the organic solvent which contains 80% by volume or 70% by volume of an aromatic hydrocarbon as a diluent by volume.

The composition of the extraction start solution (mixed aqueous solution of nickel chloride and cobalt chloride) is 170 to 210 g / L in nickel concentration, 2 to 10 g / L in cobalt concentration, and 0.02 to 0.2 g / L in copper concentration. The cobalt concentration of the back extraction residue (cobalt chloride aqueous solution) is 50 to 70 g / L.

According to FIG. 3, the slope of the regression line, that is, the distribution ratio changes depending on the concentration of the extractant, but the copper in the organic phase is reduced to an aqueous solution of cobalt chloride by lowering the copper concentration to 0.4 g / L or less. It is understood that the copper concentration can be 0.3 g / L or less.
It is a second feature of the present invention to produce this low copper concentration cobalt chloride aqueous solution.

The copper recovery stage of the present invention is a process of selectively separating and removing copper from copper, zinc and iron concentrated in the organic phase into the aqueous phase.
The stability of copper, zinc and iron in the organic phase, ie the stability of the chloro complex ion of the metal, is positively correlated with the chloride ion concentration in the aqueous phase.

FIG. 4 shows the relationship between the chloride ion concentration in the aqueous phase and the distribution ratio into the organic phase for copper, zinc and iron.
Here, among copper, zinc and iron, copper has the lowest stability in the organic phase, and is easily distributed in the aqueous phase.
Therefore, copper in the organic phase can be selectively eliminated into the aqueous phase by mixing and contacting the aqueous phase having a low chloride ion concentration with the organic phase after the back extraction.

As a result of repeated studies on the chloride ion concentration and the back extraction behavior of copper, the present inventors have found that water or dilute hydrochloric acid having a pH of 1 or more is suitable as the back extraction starting solution.
Among them, when water is used, copper is easily desorbed from the organic phase, but if hydrochloric acid of pH 1 is used, it is possible to prevent the desorption of hydrochloric acid from the organic phase, and the activity of the extractant by hydrochloric acid thereafter It is convenient because the conversion process is unnecessary.

According to the present invention, the solvent extraction step as shown in FIG. 2 is configured to adjust the copper concentration in the organic phase to 0.4 g / L or less, thereby extracting the copper concentration up to 0.2 g / L. The treatment of the starting solution becomes possible, and the copper concentration in the aqueous solution of cobalt chloride after the back extraction can be 0.3 g / L or less.
In other words, it becomes possible to cope with 10 times the copper load of the prior art (dezincification stage by alkali neutralization).

In the present invention, since copper recovery is performed without using an alkali, for example, cost reduction can be achieved as compared with the conventional zinc removal stage in which alkali neutralization is performed to remove zinc and iron in the organic matter. It is.

In addition, since the organic phase does not come in contact with a strong alkali, the copper recovery solution contains only a low concentration of COD components generated by decomposition of the organic matter, thereby reducing the COD load on the subsequent steps. .
That is, various conventional techniques (dezincification stages by alkali neutralization) can be performed by performing weak desorption using water of pH 1 to neutral region against strong desorption using conventional alkali, or in combination. It can solve the problem.
In addition, desorption of hydrochloric acid from the organic phase can also be suppressed by using dilute hydrochloric acid of about pH 1 for the copper recovery solution.

The invention will now be further described by way of examples.

This is a solvent extraction system using a counterflow multistage mixer / settler consisting of 3 extraction stages, 3 washing stages and 3 back extraction stages, and it is a tertiary amine tri-nor-octylamine (TNOA) as an extractant. The solvent extraction operation was carried out using an organic solvent containing 20% by volume of the organic solvent and 80% by volume of an aromatic hydrocarbon as a diluent.

The composition of the first extract (mixed aqueous solution of nickel chloride and cobalt chloride) is 170 to 210 g / L nickel concentration, 2 to 10 g / L cobalt concentration, 0.01 to 0.02 g / L copper concentration, zinc concentration Is 0.02 to 0.03 g / L and iron concentration is 10 to 14 mg / L, and the back extraction residual liquid (cobalt chloride aqueous solution) has a cobalt concentration of 50 to 70 g / L and a copper concentration of 0.1 to 0. It is 2 g / L.
Each flow rate is an organic flow rate of 1000 to 1300 L / min, an extraction start flow rate of 1300 to 1600 L / min, and a back extraction start flow rate of 140 to 170 L / min.

Thereafter, a part of the organic phase after the back extraction was sent to a copper recovery stage (one stage) using a mixer-settler in the same manner as in the extraction stage and the like, and mixed with neutral water.
The organic phase flow rate was 48 to 54 L / min, the aqueous phase flow rate was 48 to 54 L / min, and the O / A ratio was 0.9 to 1.1.

The results are shown in Table 1. From Table 1, it can be seen that copper in the organic phase is selectively back extracted into the aqueous phase.
The COD in the aqueous phase after copper recovery was 20 mg / L.
"Back-extraction organic" in Tables 1 and 2 represents the organic phase "a" after back-extraction in FIG. 2, and "copper recovery organic" represents the organic phase "b" after copper recovery in FIG. is there.

The solvent extraction operation was performed under the same conditions as in Example 1 except that an organic solvent containing 30% by volume of TNOA and 70% by volume of aromatic hydrocarbon was used.
Thereafter, a part of the back-extracted organic phase is sent to a copper recovery stage, and an O / A ratio of 0.9 to 1.1 is obtained in the same manner as in Example 1 except that dilute hydrochloric acid of pH 1 is used as the aqueous phase. The organic and aqueous phases were mixed.

The results are shown in Table 2. It was found that copper in the organic phase was selectively back-extracted into the aqueous phase even with pH 1 hydrochloric acid as in neutral water.

(Comparative example 1)
The solvent extraction was carried out under the same conditions as in Example 1, and then part of the back-extracted organic phase was sent to a 3 m ³ FRP tank three-stage dezincification stage (one stage), and in the first tank It was mixed with diluted caustic soda in a Japanese tank. The caustic soda concentration of the diluted caustic soda used is 118 g / L.
Thereafter, the organic phase not containing precipitate is extracted by overflow from the mixture containing the organic phase, the aqueous phase and the precipitate after alkali neutralization, and the mixture containing the remaining portion of the aqueous phase, the precipitate and the organic phase is used as a second tank The solution was sent to an acid dissolving tank and dissolved in 35% hydrochloric acid.

The organic extraction flow rate was 48 to 54 L / min, and the diluted caustic soda flow rate was 48 to 54 L / min. The amount of 35% hydrochloric acid used was 15 L / min.

The resulting COD concentration in the aqueous phase after zinc removal by alkaline neutralization was 230 mg / L.

Thus, by treating the back-extracted organic in the copper recovery stage, copper in the organic can be selectively removed and the concentration can be reduced to the target concentration, and the amount of the organic solvent withdrawn, that is, the throughput in the copper recovery stage. The copper concentration in the organic phase after back extraction is adjusted to 0.4 g / L or less.

Furthermore, as compared with the comparative example (conventional method), it is possible to reduce the COD concentration of the aqueous phase after treatment to about 1/10 without requiring caustic soda for neutralization or hydrochloric acid for acid dissolution. There is.
In addition, when the copper concentration in the organic phase further increases, the copper concentration in the aqueous phase correspondingly increases, so the amount of removal from the organic solvent is increased.

a Organic phase after back extraction b Organic phase after copper recovery

Claims

The cobalt is separated and recovered from an aqueous solution of nickel chloride containing cobalt, copper, zinc, and iron using a solvent extraction method using an organic solvent containing an tertiary hydrocarbon as an extractant and an aromatic hydrocarbon as a diluent for the organic phase. A method of removing copper chloride aqueous solution comprising the steps of (1) to (3) below in order in the method of removing copper, zinc and iron.
(Record)
(1) Extract cobalt, copper, zinc, iron into the organic phase from the aqueous solution of nickel chloride containing cobalt, copper, zinc, iron to form an organic phase containing cobalt, copper, zinc, iron, cobalt Extraction step to obtain an aqueous solution of nickel chloride from which copper, zinc and iron have been removed.
(2) Cobalt in the organic phase is desorbed from the organic phase by bringing the weakly acidic aqueous solution into contact with the organic phase containing the cobalt, copper, zinc and iron obtained in the step (1). A back extraction step to obtain an aqueous phase of a cobalt chloride aqueous solution and an organic phase containing copper, zinc and iron after back extraction.
(3) Water or dilute hydrochloric acid having a pH of 1 or more is mixed and brought into contact with the organic phase after the back extraction, and the copper in the organic phase is back extracted to the aqueous phase to recover the copper, and zinc is removed The copper recovery step, wherein the iron-containing organic phase is used as the organic solvent in the step (1).
The nickel concentration of the aqueous solution of nickel chloride containing cobalt, copper, zinc, and iron in the extraction step (1) is 170 to 210 g / L, the cobalt concentration is 2 to 10 g / L, and the copper concentration is 0.01 to 0.s. 2g / L,
By removing copper in the organic phase containing cobalt, copper, zinc and iron obtained in the step (1) until the copper concentration becomes 0.4 g / L or less, the reverse of the above (2) The copper concentration in the aqueous solution of cobalt chloride obtained in the extraction step is 0.3 g / L or less, The copper chloride aqueous solution decoppering method according to claim 1, characterized in that
The method for copper removal from an aqueous solution of nickel chloride according to claim 1, wherein the volume ratio of the organic relative aqueous phase in the copper recovery step (3) is 1.5 or less.
The method for copper removal from aqueous solution of nickel chloride according to claim 1, wherein the tertiary amine is tri-normal-octylamine (TNOA) or tri-iso-octylamine (TIOA).