Method for recovering nickel and / or cobalt

Abstract

To provide a method capable of efficiently separating and recovering nickel or cobalt by bleeding sulfur in an element state together with nickel and cobalt, from a raw material of sulfide containing nickel and / cobalt.SOLUTION: A recovery method according to the present invention comprises a step of mixing a raw material containing a sulfide containing nickel and / or cobalt with an aprotic solvent containing divalent copper halide to obtain a mother liquor containing nickel and / or cobalt and a leach residue, and an extracting step for mixing the obtained mother liquor and an acidic extractant solution to extract nickel and / or cobalt contained in the mother liquor into the acidic extractant solution, and an extraction residue.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for leaching and recovering nickel and cobalt from a raw material of sulfide containing at least one of nickel and cobalt.

Background Art

[0002] As a process for separating and recovering metals using non-ferrous metal sulfide minerals or sulfide intermediates such as nickel and cobalt as raw materials, there are a dry smelting method (dry method) in which sulfide in the sulfide is reduced to a metal single substance or a mixture (mat) of a metal single substance and sulfide and recovered, and a wet smelting method (wet method) in which sulfide is leached using an acid or an alkali in an aqueous solution, or only the metal is selectively dissolved and recovered in the aqueous solution while leaving only sulfur in the sulfide, which are roughly classified into these two methods.

[0003] Generally, in the case of so-called precious elements such as silver and copper, since the sulfide ions can be easily reduced to a metal single substance by electrons, the dry method is suitable. In the case of so-called base elements such as zinc and cadmium, since it is difficult to reduce them to metals by the electrons of sulfide ions, the wet method is suitable. Furthermore, in the case of elements such as nickel, cobalt, lead, and tin, which are in between these, both wet and dry smelting methods are employed.

[0004] In the wet smelting method of sulfide, when sulfur is completely oxidized and dissolved together with the metal, sulfuric acid is by-produced. Therefore, a selective leaching method is often used in which sulfide ions are oxidized until they become elemental sulfur, and then the metal ions leached as an aqueous solution are separated from the residual sulfur.

[0005] However, in the selective leaching method, elemental sulfur often precipitates on the surface of the sulfide during leaching and covers the surface of the sulfide. As a result, the contact between the sulfide raw material and the aqueous solution is hindered and the reaction rate tends to be low. Furthermore, when the reaction temperature exceeds the melting point of sulfur, there is a problem that the molten sulfur completely covers the sulfide surface and inhibits further metal leaching reaction, preventing leaching from proceeding.

[0006] Such a leaching inhibition phenomenon becomes more prominent as the sulfur content in the sulfide increases. Generally, the leaching rate follows the order of polysulfides (FeS2, NiS2, etc.) < sulfides (NiS, etc.) < matte (a mixture of sulfide and metal, composite sulfide).

[0007] As a method for effectively separating the elemental sulfur generated during the selective leaching of sulfides, methods such as the attrition method of physically peeling sulfur and the method of forcibly separating molten sulfur as a liquid in the presence of a surfactant have been known for a long time.

[0008] However, since a new sulfur film is formed immediately after separating sulfur by any of these methods, it is hard to say that they are perfect methods. Therefore, to most fundamentally separate sulfur, it is desirable to remove the elemental sulfur generated simultaneously with leaching in a form other than sulfuric acid.

[0009] Here, Patent Document 1 discloses a method in which chalcopyrite is dispersed in a solvent containing divalent copper halide (hereinafter also referred to as "copper(II) halide") and an aprotic polar organic solvent, for example, dimethyl sulfoxide (hereinafter abbreviated as "DMSO"), copper and iron contained in chalcopyrite are leached into the solvent and elemental sulfur is also dissolved, then the sulfur is crystallized and separated by cooling the above-mentioned solvent, and further copper is recovered as a metal single body by an electrolytic collection method.

[0010] In addition, a mixed solvent (mixed solution) in which an oxidizing agent such as divalent copper halide is dissolved in an organic solvent is also called "organic aqua regia" because it can dissolve precious metals such as gold efficiently at high speed.

[0011] However, Patent Document 1 does not disclose that it can be applied to the leaching of sulfides containing elements other than copper, such as sulfides containing nickel or cobalt and their mixtures. Also, when the leaching method using organic aqua regia is applied to the leaching of sulfides containing nickel or cobalt and their mixtures, it is necessary to separate copper(II) ions (divalent copper ions), which are oxidizing agents, from nickel ions or cobalt ions, which are elements to be recovered, after the leaching reaction.

[0012] For example, when attempting to directly electrolytically extract a non-protic solvent that is a chloride-based and separate copper, chlorine gas is generated on the anode surface, requiring equipment for recovering the chlorine gas. Additionally, there arises a problem that the oxidation of the solvent is promoted by the generated free halogen and it becomes prone to deterioration. Furthermore, since the electrical resistance (specific resistance) of DMSO is large compared to aqueous solutions such as sulfuric acid and hydrochloric acid, there is also a problem that the cell voltage during electrolysis increases, and as a result, the power consumption also increases.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] The present invention has been proposed in view of the above-described circumstances, and an object thereof is to provide a method capable of efficiently separating and recovering nickel and cobalt by leaching sulfur in a single state together with the nickel and cobalt from a raw material of a sulfide containing nickel and / or cobalt.

Means for Solving the Problems

[0015] As a result of intensive studies by the present inventors, a non-protic solvent containing divalent copper halide is used for leaching treatment of a sulfide raw material containing nickel and / or cobalt, and then solvent extraction treatment is performed on the obtained leachate (mother liquor) to separate and recover the leached nickel and cobalt, thereby finding that the above-described problems can be solved and completing the present invention.

[0016] (1) The first invention of the present invention is a method for recovering nickel and / or cobalt, comprising: a leaching step of mixing a raw material containing a sulfide containing nickel and / or cobalt with an aprotic solvent containing divalent copper halide to obtain a mother liquor containing nickel and / or cobalt and a leaching residue; and an extraction step of performing a solvent extraction treatment by mixing the mother liquor with an acidic extractant solution to extract nickel and / or cobalt contained in the mother liquor into the acidic extractant solution to obtain an extract and an extraction raffinate.

[0017] (2) The second invention of the present invention is a method for recovering nickel and / or cobalt according to the first invention, wherein the raw material contains a mixed sulfide of nickel and cobalt.

[0018] (3) The third invention of the present invention is a method for recovering nickel and / or cobalt according to the first or second invention, wherein in the extraction step, when the mother liquor and the acidic extractant solution are mixed for solvent extraction treatment, an alkali is added.

[0019] (4) The fourth invention of the present invention is a method for recovering nickel and / or cobalt according to any one of the first to third inventions, wherein the acidic extractant contains the acidic phosphoric acid ester solution.

[0020] (5) The fifth invention of the present invention is a method for recovering nickel and / or cobalt according to the fourth invention, wherein the acidic phosphoric acid ester solution contains 2-ethylhexyl 2-ethylhexylphosphonate.

[0021] (6) The sixth invention of the present invention is a method for recovering nickel and / or cobalt according to the fifth invention, wherein in the extraction step, the acidic phosphoric acid ester solution containing 2-ethylhexyl 2-ethylhexylphosphonate is mixed with an olefin-based or naphthenic diluent, and the resulting mixture is subjected to solvent extraction treatment.

[0022] (7) The seventh invention of the present invention is a method for recovering nickel and / or cobalt, which in any one of the first to sixth inventions, has a sulfur precipitation step of cooling the mother liquor to precipitate and separate sulfur contained in the mother liquor.

[0023] (8) The eighth invention of the present invention is a method for recovering nickel and / or cobalt, which in any one of the first to seventh inventions, has a monovalent copper recovery step of adding water to the mother liquor to obtain a precipitate of monovalent copper halide.

[0024] (9) The ninth invention of the present invention is a method for recovering nickel and / or cobalt, which in the eighth invention, in the monovalent copper recovery step, the addition amount of water added to the mother liquor is 1 to 3 times the volume ratio.

[0025] (10) The tenth invention of the present invention is a method for recovering nickel and / or cobalt, which in the eighth or ninth invention, to the extraction residue obtained through the extraction step, the precipitate of monovalent copper halide obtained through the monovalent copper recovery step and hydrohalic acid are added, and further an oxidizing agent is added to obtain a solution containing divalent copper halide, having a divalent copper regeneration step.

[0026] (11) The eleventh invention of the present invention is a method for recovering nickel and / or cobalt, which in the tenth invention, has a water removal step of heating the solution containing divalent copper halide obtained through the divalent copper regeneration step to volatilize and remove the moisture in the solution.

[0027] (12) The twelfth invention of the present invention is a method for recovering nickel and / or cobalt, which in any one of the first to eleventh inventions, the aprotic solvent contains dimethyl sulfoxide.

Advantages of the Invention

[0028] According to the present invention, it is possible to provide a method for efficiently separating and recovering nickel and cobalt by leaching sulfur in a single state together with the nickel and cobalt from a raw material of sulfide containing nickel and / or cobalt.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0030] Hereinafter, specific embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

[0031] The method according to the present embodiment is a method for recovering nickel and / or cobalt from a raw material containing sulfide containing nickel and / or cobalt.

[0032] Examples of the raw material containing sulfide containing nickel and / or cobalt (sulfide raw material) include raw materials containing pure nickel sulfide or cobalt sulfide, and in addition, so-called mixed sulfide (MS) which is a mixture of both sulfides. Further, examples include so-called nickel matte obtained by treating nickel ore or cobalt ore at high temperature, sulfide ore containing nickel or cobalt, or mixtures or containments thereof.

[0033] Note that this recovery method is not limited to treating the above-described sulfide raw material, and can also be applied to, for example, a treatment method using a metal containing nickel and / or cobalt as a raw material. When treating the metal, the sulfur precipitation step of precipitating and recovering sulfur from the solution, which will be described later, becomes unnecessary.

[0034] In addition, it can also be applied to a method for recovering nickel and / or cobalt from a raw material containing elements that can be extracted with an acidic extractant, such as zinc, copper, or lead, instead of nickel and / or cobalt. For example, even for sulfides and their containing substances of elements other than nickel and cobalt that exhibit similar chemical properties, by applying the treatment procedures described in detail later to perform leaching, separation, and recovery processes, they can be effectively recovered.

[0035] Hereinafter, as an example, a case where a raw material containing sulfides of nickel and cobalt, such as nickel-cobalt mixed sulfide (mix sulfide: MS), is used as the raw material to be treated will be taken, and a method for recovering nickel and cobalt from the raw material will be described in detail.

[0036] FIG. 1 is a diagram showing an example of the flow of the recovery method according to the present embodiment. As shown in FIG. 1, this recovery method includes a leaching step S1 of mixing a sulfide raw material containing nickel and cobalt with an aprotic solvent containing divalent copper halide to obtain a mother liquor containing nickel and cobalt and a leaching residue, and an extraction step S4 of mixing the obtained mother liquor with a solution of an acidic extractant to extract nickel and cobalt to obtain an extract and an extraction residue.

[0037] Specifically, as will be described later, according to the recovery method having such steps, sulfur can be efficiently leached in the form of a simple substance from the sulfide raw material containing nickel and cobalt, together with nickel and cobalt. In addition, nickel and cobalt can be separated from copper and recovered by a simple operation through a solvent extraction treatment of the solution (mother liquor) in which nickel and cobalt are leached.

[0038] In addition, in this recovery method, it is preferable to provide a sulfur precipitation step S2 of cooling the mother liquor obtained through the leaching step S1 to precipitate and separate the sulfur contained in the mother liquor. Thereby, the sulfur contained in the mother liquor can be easily separated and recovered.

[0039] In addition, in this recovery method, a monovalent copper recovery step S3 of adding water to the mother liquor to obtain a precipitate of monovalent copper halide can also be provided. Further, a precipitate of monovalent copper halide obtained through the monovalent copper recovery step and a hydrohalic acid are added to the extraction residue obtained through the extraction step, and an oxidizing agent is further added to provide a divalent copper regeneration step S5 of obtaining a solution containing divalent copper halide. By providing these steps, copper in the mother liquor can be regenerated and circulated as an oxidizing agent (divalent copper halide) used in the treatment in the leaching step, enabling more efficient treatment.

[0040] Furthermore, a water removal step S6 of heating the solution containing divalent copper halide obtained through the divalent copper regeneration step to volatilize and remove moisture in the solution can be provided. By providing such a step, the regenerated divalent copper halide can be obtained in the form of an aprotic solvent and can be repeatedly recycled.

[0041] [Leaching step] In the leaching step S1, a sulfide raw material containing nickel and cobalt and an aprotic solvent containing divalent copper halide are mixed for leaching treatment to leach nickel and cobalt. Thereby, a mother liquor (leachate) containing nickel and cobalt and leaching residue are obtained.

[0042] In the leaching reaction of mixing an aprotic solvent (organic aqua regia) containing a divalent copper compound (copper halide) with sulfides of nickel and cobalt, the action of divalent copper halide as an oxidizing agent can effectively dissolve the elemental sulfur deposited on the surface, thus suppressing the hindrance of contact between the sulfide raw material and the aqueous solution and enabling efficient leaching of nickel and cobalt.

[0043] More specifically, in the leaching step S1, a sulfide raw material containing nickel and cobalt is dispersed in an aprotic solvent, and divalent copper halide is added and heated. Then, as shown in the following [Formula 1], the sulfide ions are oxidized to elemental sulfur by the divalent copper halide ions, and at the same time, nickel and cobalt are dissolved in the solvent as halides. Note that "X" in the following [Formula 1] represents a halogen. (Ni,Co)S + 2CuX 2+ → (Ni,Co)X2 + 2CuX + S ···[Formula 1]

[0044] In an aqueous solution, sulfur is generated and precipitated on the surface of the solid particles of the sulfide raw material, and the contact between the sulfide raw material and the aqueous solution is hindered by the coating on the surface, resulting in a decrease in the leaching reaction rate. However, as described above, by performing the leaching treatment with an aprotic solvent containing divalent copper halide, the precipitated sulfur can be effectively dissolved, and a high-speed leaching reaction can be maintained.

[0045] The monovalent copper halide by-produced along with the leaching reaction does not dissolve in water but has the property of dissolving in an aprotic solvent. In particular, when an excess of alkali halide is present in the aqueous solution, the solubility of monovalent copper ions increases by forming a halogenated complex. Note that in the solvent extraction treatment in the extraction step S4 described later, an alkali is preferably added, so the alkali halide is always present in the system during circulation.

[0046] The divalent copper halide used as the oxidizing agent is not particularly limited, but from the viewpoint that both divalent and monovalent copper compounds are stable, it is preferable to use divalent copper chloride or divalent copper bromide. Among them, divalent copper chloride is particularly preferable in view of industrial price, production volume, and ease of availability. When divalent copper fluoride is used as the divalent copper halide, for example, monovalent copper fluoride as the reduction product is unstable, and a disproportionation reaction that is not preferable easily occurs between divalent copper fluoride and elemental copper. Also, when divalent copper iodide is used, iodide ions are easily oxidized by divalent copper ions to disproportionate into monovalent copper iodide and elemental iodine.

[0047] Further, as shown in the above [Formula 1], it is necessary for the divalent copper halide to contain in an aprotic solvent an amount that is 2 times the molar amount or more of nickel and cobalt contained in the sulfide raw material. Although not particularly limited, it is preferable to add the divalent copper halide to the aqueous solution after dispersing the sulfide raw material in the aprotic solvent.

[0048] The aprotic solvent is not particularly limited, and for example, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), acetone, acetonitrile, tetrahydrofuran, propylene carbonate, etc. can be used. Among them, considering that the solubility of sulfur is high, the toxicity which is an important factor in industrialization is low, the flash point is high, etc., DMSO is particularly preferable industrially.

[0049] In the leaching treatment, it is preferable to set the temperature of the aqueous solution to 100°C or higher and 120°C or lower. Since the leaching reaction has a large temperature dependence, the higher the temperature, the more preferable. However, when the temperature exceeds 120°C, the self-decomposition of the solvent is promoted and the fire risk also increases, so industrially, it is preferable to set the temperature range to 100°C or higher and 120°C or lower. By leaching within such a temperature range, an industrially practical leaching reaction rate and suppression of the self-decomposition of an aprotic solvent such as DMSO can be satisfied simultaneously.

[0050] In the case where a temperature of 100°C or higher cannot be obtained under atmospheric pressure, it is preferable to use a pressure reaction vessel such as an autoclave.

[0051] Since the leaching reaction proceeds in an organic solvent, it is difficult to measure the exact pH and oxidation-reduction potential (ORP) compared to the reaction in a general inorganic aqueous solution. Therefore, the end point of the reaction can be regarded as the time when the solid residue disappears.

[0052] [Sulfur precipitation step] In the sulfur precipitation step S2, the mother liquor obtained through the leaching step S1 is cooled to precipitate and separate the sulfur dissolved in the mother liquor.

[0053] As described above, in the leaching treatment in the leaching step S1, the sulfur generated on the surface of the solid particles of the sulfide raw material is dissolved by the divalent copper halide contained in the aprotic solvent, and the reaction can be promoted. Therefore, the resulting mother liquor contains sulfur together with the leached nickel and cobalt.

[0054] The solubility of sulfur in an aprotic solvent such as DMSO is highly temperature-dependent. Therefore, by cooling the aprotic solvent (mother liquor) after leaching containing sulfur, sulfur can be easily precipitated, separated, and recovered as single crystals. Note that sulfur exceeding the saturation concentration is distributed to the leaching residue, so sulfur can be separated as a leaching residue by solid-liquid separation after the leaching treatment in the leaching step S1.

[0055] Sulfur in an aprotic solvent easily forms a supersaturated solution, so it is difficult to measure the exact solubility. For example, the solubility of sulfur at 100°C, which is a temperature suitable for the above-described leaching treatment, is 20 g / L, and at 120°C, it is as high as 45 g / L. On the other hand, when the temperature drops below 100°C, the solubility decreases rapidly. For example, at 50°C, it is 5 g / L, and at 25°C, it is 1 g / L.

[0056] Industrially, cooling down to 50 °C can be relatively easily achieved by using a cooling tower or the like. Therefore, by cooling the mother liquor obtained from the leaching process until it reaches 50 °C or lower, that is, setting the cooling temperature to 50 °C or lower, most of the elemental sulfur dissolved in an aprotic solvent such as DMSO can be precipitated as crystals and recovered.

[0057] The lower limit temperature of the cooling is not particularly limited. For example, the melting point of DMSO, which is an aprotic solvent, is 19 °C. If cooled excessively, not only will the cooling cost increase, but the solvent itself will solidify and sulfur cannot be separated. Therefore, it is preferable to set the lower limit value to a temperature higher than the melting point of the aprotic solvent. For example, when using DMSO, it is preferable to cool the temperature of the mother liquor to a temperature in the range exceeding 19 °C and 50 °C or lower as the cooling temperature.

[0058] The sulfur precipitated by cooling can be separated by solid-liquid separation using methods such as filtration. Also, when there is leaching residue or when excessive salts such as sodium chloride accumulate in the system during the reaction process, these can be separated and removed simultaneously during the solid-liquid separation process of sulfur. Note that the sulfur precipitated by cooling has strong hydrophobicity and forms coarse crystals, so almost no physical entrainment into the aprotic solvent occurs.

[0059] [Monovalent copper recovery process] In the monovalent copper recovery step S3, water is added to the mother liquor obtained through the leaching step S1 or the mother liquor after sulfur has been precipitated and separated from the mother liquor to form and recover a precipitate of sparingly soluble monovalent copper halide.

[0060] By the leaching treatment in the leaching step S1, metal ions (nickel ions, cobalt ions) dissolved in an aprotic solvent are recovered by the solvent extraction treatment in the extraction step S4 described later. On the other hand, it is also industrially necessary to recover and reuse copper added as an oxidizing agent in the aprotic solvent. In particular, when the raw material does not contain copper and a copper compound is intentionally added and used as an oxidizing agent, if the solvent extraction treatment (treatment in the extraction step S4) is carried out with copper remaining in the mother liquor, the extraction load on the solvent increases, and the amount of alkali used in the solvent extraction treatment also increases, which is not preferable.

[0061] Also, as shown in Patent Document 1, when trying to separate copper from a chloride-based aprotic solvent (mother liquor) by electrolytic collection, not only is equipment for recovering the generated chlorine gas required and the deterioration is likely to be accelerated, but also the power consumption increases as the electrolytic cell voltage rises, and there are many problems, making it difficult to perform efficient treatment. In contrast, in the method according to this embodiment, as described later, metal ions are recovered by performing a solvent extraction treatment. And in this regard, prior to the solvent extraction treatment, by recovering copper as a sparingly soluble monovalent copper compound (copper halide), the copper in the mother liquor can be effectively recovered and reused as an oxidizing agent, and at the same time, the decrease in the extraction efficiency of nickel and cobalt leached into the mother liquor can be suppressed, enabling effective recovery.

[0062] The monovalent copper halide generated by the leaching treatment has the property of dissolving in an aprotic solvent such as DMSO that constitutes the mother liquor, but hardly dissolving in water. Therefore, by adding water to the mother liquor, the monovalent copper halide can be precipitated and separated as a precipitate. Even when an alkali halide coexists to form a halogeno complex, dissociation of the complex can be caused by the addition of water to liberate the copper halide.

[0063] In this way, by separating and recovering the monovalent copper halide, for example, it can be recycled as an oxidizing agent used in the leaching step S1 through the divalent copper regeneration step S5 described later.

[0064] The amount of water to be added is not particularly limited. The larger the amount of water added, the more preferable it is because the solubility of monovalent copper halide decreases. However, if water is added excessively, the liquid volume in the subsequent process increases and the equipment load increases. Furthermore, the energy consumption for heating required for water removal in the water removal step S6 described later increases. Specifically, from an industrial perspective, it is preferable to add about 1 to 3 times the volume of an aprotic solvent such as DMSO. Even if the amount of water added exceeds 3 times the volume of the solvent, the rate of decrease in solubility is slight, so around 3 times the volume is most preferable.

[0065] The precipitate of monovalent copper halide formed by adding water to the mother liquor can be recovered by solid-liquid separation using methods such as filtration. In addition, trace amounts of sulfides may be by-produced in the aprotic solvent such as DMSO that constitutes the mother liquor. However, due to the treatment in the monovalent copper recovery step S3, copper sulfide precipitates are formed, so they can be efficiently removed together. Note that unreacted divalent copper compounds may remain in the solution without precipitating. Therefore, in the extraction step described later, it is necessary to recover them together with nickel and cobalt.

[0066] The order of the sulfur precipitation step S2 and the monovalent copper recovery step S3 described above is not particularly limited. The order described in this specification, that is, the treatment in the sulfur precipitation step S2 may be performed first and then the treatment in the monovalent copper recovery step S3, or sulfur may be precipitated and separated in the sulfur precipitation step from the mother liquor after the treatment in the monovalent copper recovery step to recover copper.

[0067] [Extraction Step] In the extraction step S4, the mother liquor obtained through the leaching step S1, or the mother liquor after sulfur is precipitated and removed in the sulfur precipitation step S2 from the mother liquor and the monovalent copper chloride is precipitated, separated, and recovered in the monovalent copper recovery step S3, is used. The mother liquor and a solution of an acidic extractant are mixed to perform solvent extraction treatment. Through such solvent extraction treatment, an extract obtained by extracting nickel and cobalt contained in the mother liquor into the acidic extractant and an extraction residue are obtained.

[0068] Note that the "extract" refers to the phase in which the extraction target is extracted into the extractant (extractant solution) through solvent extraction treatment, and the "extraction residue" means a phase different from the phase in which the extraction target is extracted.

[0069] Since nickel ions, cobalt ions, and copper ions in the mother liquor all exist as cations, these metal ions can be extracted, separated, and recovered by a cation exchanger. Also, regarding the divalent copper compound remaining unreacted in the treatment in the above-described monovalent copper recovery step S4, since it exists as its copper ions (cations), it can also be separated and recovered by a cation exchanger.

[0070] In principle, a cation exchange type solvent and a cation exchange resin can be used as the cation exchanger. However, in the case of an ion exchange resin, there is a possibility that pores are blocked in an organic solvent and it becomes difficult to exhibit the ion exchange function. Therefore, it is preferable to use a cation exchange type solvent, that is, an acidic extractant, rather than an ion exchange resin.

[0071] Among such acidic extractants, it is preferable to use an acidic phosphate ester solution because extraction is possible in a relatively low pH range, back extraction is easy, and selective extraction of nickel, cobalt, and copper is possible according to needs. In particular, an acidic phosphate ester solution containing 2-ethylhexylphosphonic acid 2-ethyl ester is preferable.

[0072] Here, when extracting metal ions (cations) with an acidic extractant, hydrogen ions are generated and the pH decreases. Therefore, in order to make the extraction reaction proceed quantitatively, it is necessary to maintain the pH by adding an alkali as shown in the following [Equation 2]. In the following [Equation 2], "X" represents a halogen and "H-R" represents an H-type acidic extractant. (Ni,Co,Cu)X2 + 2H-R + 2NaOH → (Ni,Co,Cu)-R2 + NaX + 2H2O ···[Equation 2]

[0073] For example, divalent copper ions are completely extracted at around pH 4, cobalt ions at around pH 5, and nickel ions at around pH 8. Therefore, by adjusting and maintaining the pH in multiple steps, individual elements can be extracted at each pH. Also, from the first stage of the solvent extraction process, the pH can be adjusted and maintained at around 8 to extract copper, cobalt, and nickel all at once.

[0074] As the alkali added to adjust and maintain the pH, alkali hydroxides, bicarbonate alkalis, carbonate alkalis, etc. can be used. Among them, alkali hydroxides are particularly preferred. Note that bicarbonate alkalis and carbonate alkalis are difficult to dissolve in DMSO, which is an aprotic solvent, and there is a possibility that the extraction reaction rate between organic solvents will decrease.

[0075] Also, among alkali hydroxides, any of alkali metals and alkaline earth elements will react, but it is preferable to use alkali metal hydroxides. Considering price and availability, sodium hydroxide is particularly preferred. Note that alkaline earth element hydroxides have low solubility and may also be extracted by the acidic extractant.

[0076] The timing of adding the alkali is not particularly limited, but it is preferably added to the mother liquor or the solvent of the extractant simultaneously with or before mixing the mother liquor and the acidic extractant of the extractant.

[0077] Here, for example, the 2-ethylhexylphosphonic acid 2-ethyl ester solution, which is an acidic phosphate ester solution, is a protic solvent, and DMSO or the like that constitutes the mother liquor is an aprotic solvent. Since both have high polarity, mutual solubility is a concern. Therefore, when performing solvent extraction treatment, it is preferable to first dissolve the 2-ethylhexylphosphonic acid 2-ethyl ester solution in a hydrocarbon, particularly an olefin-based or naphthenic diluent with low polarity, and subject the resulting mixture to the treatment. This can sufficiently enhance the lipophilicity and minimize the mutual solubility. Also, this dilution can reduce the viscosity of the extractant and the extracted species, and can also improve the phase separation property with the phase of the aprotic solvent such as DMSO.

[0078] Metal ions such as nickel and cobalt extracted into the acidic extractant by solvent extraction treatment can be back-extracted by mixing any acid using a known method and recovered as an aqueous solution containing a metal salt. Also in the back-extraction operation, nickel, cobalt, and copper can be back-extracted stepwise in the same manner as the extraction operation. Furthermore, only divalent copper ions can be selectively recovered and repeatedly reused as an oxidizing agent for use in the treatment in the leaching step S1.

[0079] Note that simultaneously with the back-extraction, the acidic extractant is regenerated into a free state and can be reused again as an extractant for use in the treatment in the extraction step S4.

[0080] [Divalent Copper Regeneration Step] In the divalent copper regeneration step S5, to the extraction residue obtained through the extraction step S4, the precipitate of cuprous halide obtained through the above-described cuprous recovery step S3 and a hydrohalic acid are added, and further an oxidizing agent is added to obtain a solution containing divalent cupric halide. Thereby, a solution (organic aqua regia) containing divalent cupric halide as an oxidizing agent can be regenerated in the aprotic solvent that constitutes the mother liquor.

[0081] Specifically, cuprous halide (I) recovered through the monovalent copper recovery step S3 and hydrohalic acid are added to the extraction residue, and an oxidizing agent is further added, thereby causing a reaction as shown in the following [Formula 3] to regenerate a divalent copper compound. 2CuX + 2HX + (O) → 2CuX2 + H2O ···[Formula 3]

[0082] Preferably, hydrochloric acid is used as the hydrohalic acid. As described in the explanation of the leaching step S1, cupric halide (oxidizing agent) added to the aprotic solvent is particularly preferably cupric chloride. In this regard, by using hydrochloric acid as the hydrohalic acid in the divalent copper regeneration step S5, cupric chloride can be efficiently regenerated. Further, when circulating and using the cuprous halide, it is preferable to continuously use the same type of hydrohalic acid in order not to change the chemical properties.

[0083] The oxidizing agent is not particularly limited, but it is preferable to use either air or oxygen or both. Although it is also possible to use an oxidizing agent such as ozone, the oxidizing power is too strong and there is a possibility that by-products may remain due to oxidation. Further, instead of adding a hydrohalic acid and an oxidizing agent such as oxygen, it is also possible to rapidly oxidize the monovalent copper compound to a divalent copper compound by using free halogen. However, in that case, due to the too strong oxidizing power, there is a possibility of oxidizing and decomposing even an aprotic solvent such as DMSO.

[0084] [Water removal step] In the water removal step S6, the solution containing divalent cupric halide obtained through the divalent copper regeneration step S5 is heated to volatilize and remove the water contained in the solution.

[0085] In addition to water addition in the monovalent copper recovery step S3 described above, in the neutralization reaction in the extraction step S4 and further in the divalent copper regeneration step S5, in any case, the mixing of water into the aprotic solvent phase constituting the mother liquor cannot be avoided. Therefore, the aprotic solvent is gradually diluted, and in its original state, it becomes difficult to dissolve monovalent copper halide and elemental sulfur, and it becomes difficult to repeatedly reuse it in the treatment in the leaching step S1.

[0086] For example, DMSO has the property of not forming an azeotropic mixture with water. Therefore, by utilizing this property and heating the solution containing divalent copper halide obtained through the divalent copper regeneration step S5 to evaporate only water, water can be removed from DMSO. Note that although the separation efficiency is high even in simple distillation, it is desirable to perform fractional distillation in order to prevent loss due to entrainment of droplets.

[0087] As a result, the aprotic solvent containing divalent copper halide from which water has been removed can be effectively regenerated and can be repeatedly used again in the leaching treatment (leaching step S1).

Example

[0088] Examples of the present invention will be shown below for more specific description, but the present invention is not limited to the following examples in any way.

[0089] [Example 1] (Leaching step) Nickel cobalt mixed sulfide (Ni: 55% by mass, Co: 5% by mass, S: 33% by mass) obtained by acid leaching nickel oxide ore by a known method and adding a sulfiding agent was vacuum dried at 120°C, and 10 g of a product equivalent to 0.10 mol of S was separated. This was suspended in 200 ml of a dimethyl sulfoxide (DMSO) solvent, and then 0.2 to 0.3 mol (1.0 to 1.5 M; M = mol / L) of CuCl2 and 0 to 0.2 mol (0 to 1.0 M) of sodium chloride were added and stirred to obtain a raw material slurry.

[0090] Next, the obtained raw material slurry was heated at a temperature of 100°C to 120°C for 1 hour to 4 hours under an air atmosphere. Figure 2 shows the leaching rate of nickel under each condition. As shown in the graph of Figure 2, the higher the copper chloride concentration, the total chloride concentration, and the temperature, the higher the dissolution rate. Under the conditions of a CuCl2 concentration of 1.5 M and a temperature of 120°C, the leaching rate reached 95% after a 1-hour reaction and 100% after a 4-hour reaction, effectively dissolving nickel.

[0091] (Sulfur precipitation step) In the leaching step, the leaching solution (mother liquor) obtained by stirring and mixing for 4 hours under the conditions of a CuCl2 concentration of 1.5 M and a temperature of 120°C was cooled to 25°C over 24 hours to precipitate and recover 2.4 g of sulfur.

[0092] (Monovalent copper recovery step) After separating and removing sulfur in the sulfur precipitation step, 30 ml of the mother liquor (DMSO phase) was collected, and water was added to form a white precipitate of CuCl. The addition of water was carried out until no new white precipitate of CuCl was formed. The final amount of water added was 84 ml, which was 2.8 times the volume of the DMSO phase. Among the CuCl2 used, 38% equivalent of CuCl in terms of copper amount was recovered.

[0093] (Extraction step) To the total amount of the mother liquor after separating and recovering the precipitate of CuCl in the monovalent copper recovery step, 52.4 ml of 2-ethylhexylphosphonic acid 2-ethylhexyl (trade name: PC-88A, manufactured by Daihachi Chemical Industry Co., Ltd.), an acidic phosphoric acid ester solution (extracting agent), was added, and the solvent obtained by diluting it with 100 ml of naphthenic hydrocarbon (trade name: TECREEN N-20, manufactured by JXTG Energy Co., Ltd.) was added and mixed to perform solvent extraction treatment. While mixing the solvents, NaOH with a concentration of 1 M was added until the DMSO phase showed a colorless pH of 8. The final addition amount of 1 M-NaOH was 80 ml.

[0094] It was confirmed that copper, nickel, and cobalt were each extracted at 100% by the solvent extraction process. Also, the ratio of sulfur derived from DMSO distributed in the extractant phase was 0.2%, and the ratio of phosphorus contained in the extractant distributed in the DMSO phase was also as low as 0.1%. It was confirmed that the mutual dissolution of solvents between the two organic phases was suppressed.

[0095] (Copper(II) regeneration process) To 200 ml of the mother liquor, which is the DMSO phase from which sulfur has been separated and removed in the sulfur precipitation process, and which is the extraction residue that is a mixture of DMSO and water after going through the cuprous copper recovery process and the extraction process, 11.3 g (0.11 mol) of CuCl crystals and 26 g (0.19 mol) of CuCl2 crystals separated and recovered in the cuprous copper recovery process were added. Further, 2.6 ml (0.3 mol) of hydrochloric acid was added and stirred to form a uniform solution.

[0096] Next, air was blown into this solution as an oxidizing agent. The blowing of air was terminated when the oxidation-reduction potential of the solution (reference electrode: silver / silver chloride electrode) reached a maximum value of 453 mV.

[0097] By this treatment, a DMSO solution containing cupric chloride was obtained.

[0098] (Water removal process) Since the DMSO solution containing cupric chloride obtained in the copper(II) regeneration process still contains excess water, the solution was placed in a rotary vacuum evaporator, the internal pressure was reduced to 0.17 atm, and the temperature was raised to 90 °C and maintained at that temperature to evaporate the water in the solution.

[0099] After the temperature was raised, it was confirmed that no new distillate was generated after 30 minutes. When the DMSO in the distillate was analyzed, the water in the DMSO was at a low concentration of 2.3%. It was confirmed that the water was effectively removed.

[0100] [Comparative Example 1] 200 ml of an aqueous solution containing 0.5 M of divalent copper chloride and 1 M of nickel chloride was suspended with 10 g of the nickel-cobalt mixed sulfide used in Example 1 and stirred and mixed at 100 °C for 2 hours. Fig. 2 also shows the nickel leaching behavior in the treatment of Comparative Example 1. As a result, in the aqueous solution, sulfur precipitated with the leaching reaction remained covering the surface of the nickel-cobalt mixed sulfide, and it was confirmed that the nickel leaching rate after the completion of the 2-hour reaction remained at a low level of about 45%.

Industrial Applicability

[0101] According to the present invention, by bringing an aprotic solvent containing divalent copper halide into contact with a sulfide raw material containing nickel and / or cobalt, nickel and / or cobalt can be effectively leached without being affected by elemental sulfur that hinders leaching. Then, by solvent-extracting the leachate (mother liquor), nickel and / or cobalt can be effectively recovered by an economical and efficient operation.

[0102] In addition, sulfur, which is a constituent component of the raw material, can also be efficiently separated and recovered, and divalent copper halide used as an oxidizing agent in the leaching treatment and the aprotic solvent as a dissolution medium can be easily regenerated and reused.

[0103] Thus, the recovery method according to the present invention can be applied to the industrial wet smelting fields of nickel and cobalt.

Claims

1. An leaching step of mixing a raw material containing a sulfide containing nickel and / or cobalt with an aprotic solvent containing divalent copper halide to obtain a mother liquor containing nickel and / or cobalt and a leaching residue; An extraction step of performing a solvent extraction treatment by mixing the mother liquor with an acidic extractant solution to obtain an extract solution in which nickel and / or cobalt contained in the mother liquor is extracted into the acidic extractant solution and an extraction residue solution; and having, A sulfur precipitation step of cooling the mother liquor to precipitate and separate sulfur contained in the mother liquor; A method for recovering nickel and / or cobalt.

2. The raw material contains a mixed sulfide of nickel and cobalt, The method for recovering nickel and / or cobalt according to Claim 1.

3. In the extraction step, when mixing the mother liquor and the acidic extractant solution for performing a solvent extraction treatment, an alkali is added. The method for recovering nickel and / or cobalt according to Claim 1 or 2.

4. The acidic extractant solution contains an acidic phosphate ester solution, The method for recovering nickel and / or cobalt according to any one of Claims 1 to 3.

5. The acidic phosphate ester solution contains 2-ethylhexyl phosphonic acid 2-ethylhexyl, The method for recovering nickel and / or cobalt according to Claim 4.

6. In the extraction step, the acidic phosphate ester solution containing 2-ethylhexyl phosphonic acid 2-ethyl ester is mixed with an olefin-based or naphthene-based diluent, and the obtained mixed solution is subjected to a solvent extraction treatment. The method for recovering nickel and / or cobalt according to Claim 5.

7. A leaching step of mixing a raw material containing a sulfide containing nickel and / or cobalt with an aprotic solvent containing divalent copper halide to obtain a mother liquor containing nickel and / or cobalt and a leaching residue; An extraction step of performing a solvent extraction treatment by mixing the mother liquor with an acidic extractant solution to obtain an extract solution in which nickel and / or cobalt contained in the mother liquor is extracted into the acidic extractant solution and an extraction residue solution; and having, A monovalent copper recovery step of adding water to the mother liquor to obtain a precipitate of monovalent copper halide. The method for recovering nickel and / or cobalt.

8. In the monovalent copper recovery step, the addition amount of water added to the mother liquor is 1 to 3 times by volume. The method for recovering nickel and / or cobalt according to Claim 7.

9. To the extraction residue obtained through the extraction step, the precipitate of monovalent copper halide obtained through the monovalent copper recovery step and hydrohalic acid are added, and an oxidizing agent is further added to obtain a solution containing divalent copper halide, which has a divalent copper regeneration step. The method for recovering nickel and / or cobalt according to claim 7 or 8.

10. It has a water removal step of heating the solution containing divalent copper halide obtained through the divalent copper regeneration step to volatilize and remove the water in the solution. The method for recovering nickel and / or cobalt according to claim 9.

11. The aprotic solvent contains dimethyl sulfoxide. The method for recovering nickel and / or cobalt according to any one of claims 1 to 10.

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