JP7194975B2 - Method for recovering copper from chalcopyrite and solvent system used for the method - Google Patents

Description

The present invention relates to a method of recovering metals from ores, in particular to a method of recovering copper from chalcopyrite and a solvent system used in the recovery method.

Copper is the metal material with the third largest production volume in the world. Copper ores are classified into three types: primary sulfide ores (chalcopyrite (CuFeS2), etc.), secondary sulfide ores (chalcopyrite (Cu2S), etc.), and oxide ores (chalcopyrite (Cu2O), etc.). Among them, most of the copper produced in the world is obtained from chalcopyrite (CuFeS2).

Methods for producing copper from ores are generally divided into pyrometallurgical methods and hydrometallurgical methods. Pyrometallurgical refining is a method of producing electrolytic copper through an electrolytic refining process after removing impurities such as iron and sulfur through a chemical reaction through heat treatment. The pyrometallurgical method is an effective method for copper sulfide ores such as chalcopyrite (CuFeS2), which is a primary sulfide ore, but it is not economically viable unless ores with a high coarse ore grade are used.

On the other hand, the hydrometallurgical method is a method in which copper is leached from oxide ore (Cu2O, etc.) with a sulfuric acid acid solution, only copper ions are extracted by two-layer separation, and finally electrolytic copper is produced through an electrowinning process. Established as Extraction-Electro-Winning (SX-EW method).

Copper ore is a non-renewable resource, and its crude ore grade has been significantly declining in recent years. Therefore, the pyrometallurgical method has become economically unviable as a method of producing copper from low-grade ores. On the other hand, the above SX-EW method cannot be applied to chalcopyrite (CuFeS2), which accounts for the majority of copper ore, and the wet treatment process for low-grade chalcopyrite (CuFeS2) is still a problem. Currently, it has not been commercialized. In the acidic solution of sulfuric acid used in the SX-EW method, the chalcopyrite surface is passivated, so the copper leaching rate from the chalcopyrite (CuFeS2) is very slow. This is because there are drawbacks such as only a limited amount of leaching.

In recent years, bioleaching technology for chalcopyrite using bacteria has been studied, but bioleaching generally has the drawback that the rate of metal leaching is slow.

In addition, Patent Document 1 filed by the applicant himself shows that gold, palladium, silver, and platinum can be dissolved in a copper bromide-containing dimethyl sulfoxide solvent, but there is no description regarding dissolution of chalcopyrite. .

WO2014/156300

Based on the above background, an object of the present invention is to provide a simple and economical recovery method for recovering copper from chalcopyrite and a solvent system used in the recovery method.

The inventors of the present invention have made intensive studies to solve the above problems, and found that the use of an organic solvent system containing a copper halide enables dissolution and deposition of the desired copper in a relatively short period of time. and completed the present invention.

According to one aspect of the present invention, in order to solve the above problems, the step (A) of dissolving chalcopyrite in a solvent system containing copper halide and an aprotic polar organic solvent, and dissolving the chalcopyrite It includes a step (B) of depositing copper from the dissolved solvent system by electrowinning.

Furthermore, it is desirable if the copper halide is selected from copper(I) bromide, copper(II) bromide, copper(I) chloride or copper(II) chloride.

Furthermore, it is preferred that the aprotic polar organic solvent is selected from dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, tetrahydrofuran, propylene carbonate or mixtures thereof.

Additionally, it is desirable if the solvent system further comprises sodium or potassium halide.

Another aspect of the present invention relates to a solvent system comprising a copper halide and an aprotic polar organic solvent used to dissolve chalcopyrite and recover copper.

Furthermore, it is desirable if the copper halide is selected from copper(I) bromide, copper(II) bromide, copper(I) chloride or copper(II) chloride.

Furthermore, it is preferred that the aprotic polar organic solvent is selected from dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, tetrahydrofuran, propylene carbonate or mixtures thereof.

Furthermore, it is desirable to further contain sodium halide or potassium halide.

Until now, there was no commercially applicable hydrometallurgical method for chalcopyrite (CuFeS2), which is the most consumed copper ore. In the meantime, according to the present invention, it is possible to leaching and refining copper from chalcopyrite (CuFeS2) by a simple procedure, in a short time and with very high efficiency, and it will become the world's copper It makes a great contribution to sustainable production.

Furthermore, since copper ions generally exist stably as divalent ions in an aqueous solution, 2 mol of electrons e are required to produce 1 mol of copper. However, in an aprotic polar organic solvent, copper ions exist stably as univalent ions, so only 1 mol of electron e is needed to produce 1 mol of copper, which is halved. Therefore, according to the present invention, since the amount of electric power required for electrowinning can be halved, there is also the advantage that the energy saving effect is remarkably large.

FIG. 4 is a diagram showing extracted sulfur crystals;

Embodiments of the present invention will be described below. The scope of the present invention is not restricted by these descriptions, and other than the following examples can be appropriately changed and implemented without impairing the gist of the present invention.

The method for recovering copper from chalcopyrite in the present invention comprises A) a step of dissolving the target chalcopyrite in a solvent system containing a copper halide and an organic solvent such as an aprotic polar organic solvent, and B) the above It includes the step of depositing copper by electrowinning from a solvent system in which chalcopyrite is dissolved.

The solvent system used in step A) is for dissolving the chalcopyrite and is typically an organic solvent containing copper halide. The configuration of the solvent system will be described below.

The organic solvent is not particularly limited as long as it can dissolve copper ions generated by oxidation-reduction reaction with copper halide, but it is preferably a polar aprotic organic solvent. Examples of such aprotic polar organic solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), acetone, acetonitrile, tetrahydrofuran (THF), dimethylacetamide, methyl acetate, ethyl acetate, butyl acetate, propyl acetate. , propylene carbonate and the like. A mixed solvent containing two or more of these can also be used. Among these, a structure having a sulfoxide group such as DMSO is particularly preferable.

The copper halide used in the present invention is copper fluoride, copper chloride, copper bromide, or copper iodide, each of which can be a monovalent or divalent salt. Preferred are copper(I) bromide (CuBr), copper(II) bromide (CuBr2), copper(I) chloride (CuCl) or copper(II) chloride (CuCl2).

It is believed that the higher the content of the copper halide in the solvent system, the greater the amount of copper dissolved. is.

The solvent system used in the present invention may further contain an alkali metal halide as an auxiliary component for the purpose of increasing the dissolution rate and amount of copper. Sodium halide or potassium halide is preferred. As for the type of halogen, it is desirable to use one that dissociates in a solvent to produce the same halogen anion as the above copper halide (that is, sodium bromide or potassium bromide in the case of copper bromide).

The content of these additional components in the solvent system is not particularly limited, but is used in the range of 0.5 to 10 times, preferably 1 to 2 times the concentration in the copper bromide solution. be able to.

The electrolytic winning in the step B) in the recovery method of the present invention is configured such that the copper ions dissolved in the solution in the step A) are deposited by the cathode electrode (negative electrode) and recovered.

Generally, in an aqueous solution, copper ions exist stably as divalent ions, so 2 mol of electrons e are required to produce 1 mol of copper. However, in an aprotic polar organic solvent, copper ions exist stably as univalent ions, so only 1 mol of electron e is needed to produce 1 mol of copper, which is halved. Therefore, according to the present invention, the amount of electric power required for electrowinning in step B) can be halved, and the energy saving effect is remarkably large.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these.

For example, in copper bromide-containing dimethyl sulfoxide solvent, copper ions are known to act as a strong oxidizing agent and dissolve precious metals, but there is no report on chalcopyrite.

Therefore, chalcopyrite was dissolved using this solvent (copper bromide-containing dimethyl sulfoxide solvent). A chalcopyrite dissolution experiment was conducted using temperature conditions etc. as parameters, and it was confirmed that copper Cu and sulfur S contained in chalcopyrite were completely dissolved after about 4 hours at 100 ° C. In addition, it was found that iron (Fe) remained as a residue and was separated. Table 1 below shows the composition of copper (Cu), sulfur (S) and iron (Fe) in the chalcopyrite in which the leaching experiments were performed. Furthermore, Table 2 below shows the mass of the sample used in the leaching experiment, the mass of the residue, and the percentage of residual Cu in the residue. Since the residual Cu in the residue was 0%, it is clear that the copper Cu contained in the chalcopyrite was completely dissolved. In addition, in Table 2, the mass ratio of the residue is large, but it is considered that the mass ratio of the residue is large because components other than copper (Cu), sulfur (S) and iron (Fe) are also included.

Furthermore, it was discovered that sulfur precipitates as single crystals by cooling a solvent in which copper and sulfur are completely dissolved. FIG. 1 shows the state of precipitated sulfur crystals. This also made it possible to separate sulfur. Then, the copper ions dissolved in the solvent after the sulfur is separated can be deposited at the cathode electrode (negative electrode) by electrowinning to produce (recover) copper.

It was confirmed that with the configuration described above, iron, sulfur, and copper can be completely separated from chalcopyrite (CuFeS2) by a simple procedure in a short time with extremely high efficiency.

By adding an alkali metal halide to the solvent as an auxiliary component, the dissolution rate and amount of copper can be increased, making it possible to operate the process of recovering copper from chalcopyrite with even higher efficiency. becomes.

The effects of this embodiment are as follows.
(1) There was no commercially applicable hydrometallurgical method for chalcopyrite (CuFeS2). It has the advantage of allowing the leaching and smelting of copper from copper ores (CuFeS2) by a simple procedure in a short time and with very high efficiency.
(2) Generally, in an aqueous solution, copper ions exist stably as divalent ions, so 2 mol of electrons e are required to produce 1 mol of copper. However, in an aprotic polar organic solvent, copper ions exist stably as univalent ions, so only 1 mol of electron e is needed to produce 1 mol of copper, which is halved. Therefore, according to the present embodiment, since the amount of electric power required for electrowinning can be reduced by half, there is also the advantage that the energy saving effect is remarkably large.

In addition, in the embodiments and examples of the present invention, the method for recovering copper from chalcopyrite has been described. However, this recovery method is used as a method for recovering zinc (Zn) from sphalerite (ZnS), and also as a method for recovering zinc (Zn) from nickel sulfate ((Fe, Ni)9S8) and nickel-containing pyrrhotite ((Fe, Ni)1 -xS) can also be applied as a method for recovering nickel (Ni).

INDUSTRIAL APPLICABILITY The present invention is industrially applicable as a method for recovering metals from ores, particularly as a simple and economical method for recovering copper from chalcopyrite and as a solvent system used in the method.

Claims (8)

A step (A) of dissolving chalcopyrite in a solvent system containing a copper halide and an aprotic polar organic solvent, and a step (B) of precipitating copper by electrowinning from the solvent system in which the chalcopyrite is dissolved. A method for recovering copper from chalcopyrite, comprising: 2. A process for recovery of copper from chalcopyrite according to claim 1, wherein said copper halide is selected from copper(I) bromide, copper(II) bromide, copper(I) chloride or copper(II) chloride. . 3. Process for recovering copper from chalcopyrite according to claim 1 or 2, wherein the aprotic polar organic solvent is selected from dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, tetrahydrofuran, propylene carbonate or mixtures thereof. A method of recovering copper from chalcopyrite according to any one of claims 1 to 3, wherein the solvent system further comprises sodium halide or potassium halide. A solvent system comprising a copper halide and an aprotic polar organic solvent used to recover copper by electrowinning from a solvent system in which chalcopyrite is dissolved. 6. The solvent system of claim 5, wherein the copper halide is selected from copper(I) bromide, copper(II) bromide, copper(I) chloride or copper(II) chloride. 7. Solvent system according to claim 5 or 6, wherein the aprotic polar organic solvent is selected from dimethylsulfoxide, dimethylformamide, acetone, acetonitrile, tetrahydrofuran, propylene carbonate or mixtures thereof. A solvent system according to any one of claims 5 to 7, further comprising sodium or potassium halide.

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