SU1734577A3 - Method of copper extraction from the aqueous solution, containing chlorine ion - Google Patents

Abstract

This invention relates to methods for extracting copper by extraction from solutions obtained by leaching copper-containing sulfide ores with ferric chloride solutions. The purpose of the invention is to strengthen the process. In the proposed method of extracting copper from these solutions, the substituted pyridine containing the group (COX) p. where X is the OR group, R is a branched chain alkyl group, and both R. groups contain together 16-32 carbon atoms. 5 h. the item f., 2 tab. baking is a formidable challenge. The invention is a method for extracting valuable metals from aqueous solutions containing halide ions using metal extractants, some properties of which satisfy the stringent requirements of the extractant for use in the system. The purpose of the invention is to simplify the method. According to the invention, the method for extracting copper from aqueous solutions containing chloride ion involves treating the solutions with an extracting agent and re-extracting copper, and using substituted pyridine of the formula XJT (i) N where X-rpynna-ORi 00 C XI co XI with

Description

Ri is an alkyl group of a branched chain, and both groups of RI contain together 16-32 carbon atoms.

An RI may be an isomeric mixture of groups containing the same number of carbon atoms, or a mixture of groups containing different amounts of carbon atoms (which may themselves be an isomeric mixture), for example a mixture of different alkyl groups. If RI is a mixture of groups containing different numbers of carbon atoms, the average number of carbon atoms is preferably 9-24.

The strongly branched Ri groups can be obtained by the reaction of pyridine-carboxylic acid with alcohols obtained by condensation by the method of Herbert (Guerbert) and aldol condensation. Such alcohols are distinguished by branching in the beta-position with respect to the hydroxyl group and have the general formula

no-sn2-sn

/ R

Rs

In general, R4 contains 2 carbon atoms less than Rs. and the Ri groups derived from these alcohols include, for example,

-sn2-snSSbN13

-sn2-sn with H15

SeN1E

C “H2;

R4 and RS can be straight chain or branched alkyl groups, and can also be isomeric mixtures of alkyl groups. A mixture of strongly branched alcohols can be obtained by Herbert condensation or by aldol condensation of mixtures of alcohols and aldehydes, respectively.

Both groups R i in formula T are preferably the same and are straight chain or branched alkyl groups. It has been found that in order to achieve the required solubility of the complex metal compound in the preferred solvents, both RI groups, preferably together, contain a total of 16-32 carbon atoms. RI groups may contain a mixture of isomers, for example, a mixture of nonyl isomers derived from isononanol by hydro formulating the mixture of octenes. mixtures of decyl isomers derived from isodecanol. or a mixture of tridecyl isomers derived from tridecanol.

The method according to the invention can be used for solvent extraction.

copper from aqueous solutions obtained by leaching halogen or pseudohalide of sulfur-containing copper ores, for example, from solutions obtained by leaching ores, for example chalcopyrite, aqueous solutions of ferric chloride (3) or copper chloride.

Leaching of ores, such as complex sulfide ores, for example leaching of copper pyrites, using, for example, an aqueous solution of ferric chloride containing hydrochloric acid, leads to the formation of leach liquors containing ions and monovalent

copper, ions of bivalent and trivalent iron and an excess of chloride anion. The ratio of the amounts of monovalent copper ions to divalent copper depends on the selected leaching conditions. Sulfur content

in the ore can be precipitated in the form of elemental sulfur. Although the scope of the invention should not be construed as being limited to the processing of any particular halide-containing aqueous solution, typical

solutions obtained by leaching copper pyrite with acidified ferric chloride may contain copper at a concentration of 10–60 g per liter of copper, iron at a concentration of 50–150 g per liter, and salt

acid at a concentration of 0.1–1 M, and a total chloride ion content of 2–8 M. Some leaching systems can produce as high a total chloride ion content as 10 or 12 M. All occurring

in practice, leach solutions may also contain varying amounts of many other metals present in the ore oil. Some leach solutions may contain high

levels of special metals such as zinc in addition to copper.

The proposed method is included in various methods of complete recovery.

metals from their ores or from other metal-bearing sources, which may vary depending on the metal in question and on the nature and composition of the leach solution. This method is not limited to one general method of metal extraction, however, the strict conditions imposed on the pyridine extractant can best be illustrated if the solvent extraction method is considered as a stage in a single process for extracting metal from ore. For example, a single method that is particularly suitable for leaching solutions with high levels of copper ion involves the following steps.

1. Leaching of the ore with aqueous solutions of ferric chloride (3) or copper chloride (2) and removing the formed elemental sulfur.

2. Contacting the leach liquor from step 1 (in which ferric ion is at least partially reduced to ferrous ion) with a solution of the extractant in a water-immiscible solvent, whereby the copper is transferred to the organic phase in the form of a chloride-containing complex compound with the extractant.

3. Separation of the organic phase containing the complex copper compound with the extractant from the aqueous phase containing ferric chloride / ferrous chloride.

4. Contacting the organic phase from stage 3 with an aqueous stripping solution, which is water or containing a lower chloride ion concentration, whereby the chloride-containing complex compound of copper with the extractant becomes unstable and the copper goes into an aqueous stripping solution.

5. Separation of the organic phase containing the desorbed extractant from the aqueous stripping solution containing copper chloride (2).

6. Electrolysis of the stripping solution from step 5 to recover the copper. The electrolysis step is carried out in such a way that the oxidation of the ferrous ion due to the transfer of chloride ion occurs in the anode compartment with that. so that the solution leaving the cathode compartment is deprived of both copper ions and chloride ions. Alternatively, chlorine gas can be released at the anode and can be used as an oxidizing agent to regenerate the leach liquor.

In order to preserve the overall stoichiometry of the reaction sequence, it is necessary to provide additional oxidation of ferrous ion to ferric and to remove iron continuously entering the system from copper pyrite (CuFeSa), for example, in the form of iron oxide, such as bog iron ore.

For a fully integrated process, the solutions need to be recycled between different stages. Thus, the aqueous stripping solution used in stage 4 is preferably obtained from electrolysis stage 6, and preferably it is the solution constituting the cathode compartment, which is devoid of both copper ions and ions

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chlorine. Similarly, the organic phase containing the desorbed extractant which is separated in stage 5 is preferably recycled to the stage.

extraction 2. A solution of ferric chloride (3), withdrawn from electrolysis stage 6, can be returned for subsequent leaching of the ore.

Consider first the extraction stage.

0 2 and the stage of extraction of the extractant 4; while the extraction, for example, of the ion of divalent copper extractant can be represented by the following equation:

21 0rg + Cu4 Nvodn + 2HGvodn (L2CuCl2) opr.

This equation is a simplified representation of a very complex process, but serves to illustrate the formation of the neutral organic phase of the complex copper compound and extractant (L), which is dominant in this method. Other equations can be used to represent the extraction and separation of monovalent copper ion.

5 or other metals extractant.

In this equation, it is assumed that the extractant acts as a monodentate ligand. Under certain conditions other varieties may form. for example, oligomeric complex compounds, such as L.2 (CuCl2) n. The formation of oligomeric species, as a rule, is undesirable, since copper extraction efficiency decreases, and, in addition,

5 oligomeric complex compounds tend to have low solubility in organic solvents.

The equation also illustrates the reversible nature of the extraction, so

0, the complex compound of copper and extractant in the organic phase can be separated upon contact with water or with an aqueous solution having a reduced chloride or copper content, so that the copper becomes aqueous.

5 phase, and the free extractant is at least partially regenerated in the organic phase.

The most effective desorption is achieved by using water as a stripping medium, and the proposed method can be combined with the stripping stage with water. However, in a fully integrated process, it is preferable to desorb the loaded

5 extractant solution, which is obtained from the stage of electrolysis and is devoid of copper ions and chlorine. In a special case, an aqueous phase containing about 40 or 50 grams of copper per liter can be introduced into the electrolyzer. It can still leave it, still having 30 grams of copper

per liter or higher. It is necessary for the extractant to be able to efficiently extract copper from the leach liquor while desorbing it with a solution containing relatively high levels of copper. Preferred extractants for use in such a process can be desorbed with an aqueous solution containing relatively high levels of copper, for example, 20-35 grams per liter.

Since the leach liquor contains high levels of iron, it is very important that the extractant has good selectivity for copper compared to iron. Extractants according to the invention have this property. In an integrated system, where copper is extracted by electrolysis of an aqueous stripping solution rich in copper content, selectivity for copper is of particular importance compared with silver and other slightly extracted ore components. The reason for this is that although metals such as zinc and cadmium are more electronegative than copper, and they do not electrolytically precipitate with it, however, silver precipitates with copper and, in addition, adversely affects the physical properties of copper. so that expensive electrolytic refining stages are needed. Preferred extractants according to the invention have an exceptional selectivity for copper as compared with silver under appropriate operating conditions.

Another property that is important for the extractant in this process is the lack of substantial protonation of the acid leach from the acidic liquor. Such protonation can be represented by the equation

(Vod (LH Cl) org,

where b is the extragent. Such protonation of the electron does not only transfer the hydrochloric acid to the organic phase, creating an unnecessary concentration of chloride at the desorption stage, but it is also associated with a loss of copper selectivity with respect to silver and other components that are contained in an insignificant amount, such as antimony and mouse to. In addition, the preferred extractants according to the invention have excellent resistance to protonation, even when in contact with relatively acidic leach solutions.

Pyridine-3 5-dicarboxylic acid bis-esters, such as bis-nonyl ester, are weak extractants that, moreover, have a high selectivity for copper compared to zinc and provide an opportunity to extract zinc from leaching liquors containing high levels of both copper and zinc.

Examples of suitable organic solvents not miscible with

With water, there are aliphatic, aromatic and alicyclic hydrocarbons, chlorinated hydrocarbons such as perchlorethylene, trichloroethane and trichloroethylene. Mixtures of solvents can be used. Especially preferred in conventional hydrometallurgical practice are mixed hydrocarbon solvents, such as petroleum fractions (e.g., kerosene), which have high

0 boiling point, high flash point with different content of aromatic hydrocarbons, in general, hydrocarbon solvents having high aromatic content

5 hydrocarbons, for example AROMAZOLE H, which consists essentially of a mixture of trimethylbenzenes. Imperial Chemical Industries (PLC) is commercially supplied with a higher solubility of the extractant and its complex compound with copper, while kerosene, having a relatively low content of aromatic hydrocarbons, such as ESCAID 100, which is

5 product of oil distillation, containing 20% of aromatic hydrocarbons. 56.6% of paraffins and 23.4% of naphthenes. supplied by the company ESSO, may in some cases improve the hydrometallurgical characteristics of the extractant. Factors affecting the solubility of the extractant and its complex compound with copper are complex, but in general extractants with highly branched substituents and / or

5 isomeric mixture of substituents, have a relatively high solubility.

The concentration of the extractant in a water-immiscible organic solvent can be chosen such that

0 corresponded to the leach liquor being processed. Typical values of the extractant concentration in the organic phase are about 0.1-2 mol / l solution, with a particularly appropriate limit of 0.2-0.8 mol / l organic solvent.

The extraction step and the separation step in the solvent extraction process can be carried out at ambient temperature. However, the resulting transfer of copper from leach liquor to the stripping solution can be improved if the extraction step is carried out at ambient temperature, while the separation step is carried out at elevated temperature, for example, up to 50 ° C. It has also been found that undesirable formation and accumulation of oligomeric extractant and copper complexes can be avoided if the separation step is carried out at elevated temperatures (e.g., up to 50 ° C).

PRI me R A (comparative). (2- (p) Hexyldecyl) nicotinate was prepared as follows.

A mixed mixture of nicotinic acid (61.5 parts), dimethylformamide (0.63 parts) and xylene (174 parts) was heated to 80 ° C under a condenser installed for refluxing. Thionyl chloride (1-2 65.5 hours), and at the time of the addition, the temperature of the reaction mixture was raised to 90-95 ° C. The mixture was then stirred at 90-95 ° C for 3 hours. Then the condenser was set for distillation and the temperature was raised until the excess of the embossed chloride was distilled and the xylene was distilled. The mixture was then allowed to cool to 80-85 ° C and 2- (p) hexyldecanol (112 h) was added over 30 minutes. The mixture was stirred at 80-85 ° C for 2 hours, then cooled to room temperature and extracted with sodium hydroxide solution (40 hours) in water (165 hours). The xylene solution was washed with a large amount of water without alkali, and the xylene was distilled under reduced pressure to obtain (2-hexydecyl) nicotinate (147 hours) as a seed of California gray pine. Purity was estimated at 95% by titration of the sample with normal 10% perchloric acid in an acetic acid medium. The compound was distilled, i.e. bale. 176-184 ° with the addition of 0.4 mm Hg. Art., having received 109 hours of straw-colored liquid, which had a purity of 98- 99%.

The ability of (2- (p) hexyl-decyl) nicotinate to extract copper from an aqueous solution containing chloride ion was investigated.

An aqueous solution (A) was prepared which had a concentration of 0.1 M copper chloride (2) (copper content 6.35 g / l) and 0.1 M hydrochloric acid, and also contained an additional 250 g / l calcium chloride dihydrate. This solution was then stirred for 15 minutes with an equal volume of solution (B), which was a 0 2 M solution of (2-hexydecyl) nicotinate in Arozamol N. The layers were allowed to separate and settle,

and they were analyzed separately to determine the copper content. The amount of copper, initially present in A, which turned into B, was 44.5%. The resulting loaded organic solution B was then stripped with an aqueous solution (C) containing 0.472 M of copper chloride (2), i.e. a solution containing 30 g / l of copper. It was found that copper

0 goes from the organic phase to the aqueous solution. The amount of copper initially present in A, which was then transferred to solution C, was 25.5%. Transfer of hydrochloric acid from solution A to solution B

5 was negligible.

The extraction of copper with the same extractant from a stronger acid solution was also investigated. Used the same solutions and methods as before, for

0 except that solution A had a concentration of 1.0 M, and not 0.1 M for hydrochloric acid. The amount of copper extracted into the organic solution (B) and copper, which finally passed into the aqueous

5 solution of copper chloride (2) (C), respectively, was 47.8 and 30.6%. The amount of hydrochloric acid that passed from solution A to solution B was measured under these very acidic conditions. Expressed as a percentage

Because of the amount of acid that would be transferred if each molecule of the ligand was bound to one molecule of hydrochloric acid, the amount of acid transferred was only 1.9%.

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EXAMPLE 1 Pyridine-3,5-dicarboxylic acid bis-isodecyl ester was obtained by the method of a comparative example from pyridine-3,5-dicarboxylic acid and technically pure isodecanol (1CI Petrochemicals Division) using modified amounts of reagents that require stoichiometry. Toluene was used as a reaction solvent for 5 xylene, and the temperature was maintained at 80-82 ° C for 4 hours after the addition of embossing chloride. After the esterification reaction, the solution was cooled, washed with a dilute sodium hydroxide solution,

0 hydrochloric acid, 0.5 M hydrochloric acid and water. The solution was treated with activated carbon (8% relative to the expected weight of the product), the solvent was evaporated under reduced pressure, and the residue was distilled (boiling range 200-210 ° C at a pressure of 0.08 mm Hg), obtaining a product having an estimated purity of 97, five%. This bis-ester was evaluated as an extractant for copper from aqueous solutions containing chloride ion.

An aqueous solution (A) was prepared which had a copper chloride (2) concentration of 0.1 M (6.35 g / l copper), 0.1 M hydrochloric acid and contained 250 g / l sodium chloride dihydrate, while the ion concentration chloride was 3.7 m. This solution was shaken for 1 min with an equal volume of solution (B), which was a solution at a concentration of 0.2 M of isodecanol pyridine-3,5-dicarboxylic acid diester in ESCAID 100. Layer m was allowed to separate, the aqueous layer was analyzed for copper content, and the solvent layer was analyzed for acid content, Eseniya copper, copper content, initially present in the solution A and the solution which is passed into B was 22%. The transfer of hydrochloric acid to solution B was not noted.

To assess the effectiveness of the extractant for use with leach solutions containing high levels of the total chloride ion, the test was passed using the solution (A), which contained copper chloride (0.1 M), hydrochloric acid (0.1 M) and 700 g / L sodium chloride dihydrate, giving a total chloride ion concentration of 9.8 m. Copper content. first present in solution A and then transferred to solution B, it was 80%, while no transfer of hydrochloric acid into solution B was observed,

To assess the effectiveness of the extractant for use with leach solutions containing high levels of the ion of total chloride and high levels of acid, the usual test method was repeated using solution A, which contained copper chloride (2) (0.1 M), hydrochloric acid (1, OM ) and sodium chloride dihydrate (700 g / l), thus obtaining a total chloride ion concentration of 10.7 M.

The results show that the copper content, initially present in solution A, which then passed into solution B, was 79% and that 6% hydrochloric acid passed into solution B,

Thus, although a relatively low copper recovery is obtained from a solution with a concentration of 3.7 M of total chloride ion, exceptional extraction of copper occurs without acid transfer from solutions containing a total chloride ion concentration of 9.8 M, and low levels of acid transfer are achieved even when the total chloride ion concentration is 10.7 M.

Examples 2-8. The effect of various ester groups on the solubility of the copper ligand (2) chloride complex in a concentrated solution in a nonpolar solvent was studied as follows.

Pyridine-3,5-dicarboxylic acid bis-esters were obtained by esterifying pyridine-3,5-dicarboxylic acid with a variety of different alcohols by the method of Example 1 (see Table 1). Each ester, in turn, was prepared in

0 as a 0.5 M solution in ESCAID 100 and filled with copper chloride (2) to about 75% of the theoretical amount based on LaCuCI stoichiometry, where L is the bis-ester, by shaking

5 with a double volume of an aqueous solution containing 0.1 M HCl, 0.4 M CuCl2, and also 250 g / l of calcium chloride dihydrate. Any release of a complex metal-ligand compound from an organic

0 solution (test 1). If the release did not occur, then the organic solution was filled to about 100% of the theoretical value by shaking with a second aqueous solution, which differed from the first one only with 500 g / l calcium chloride dihydrate. Again, any separation of the complex from the organic solution was noted (test 2). The results are shown in Table. one.

0 The results show that the bis-esters in Examples 2-5 and 8 should be used in a more dilute solution or in a more polar solvent than ESCAID 100, for example in a solvent having a higher content of aromatic hydrocarbons than this Moreover, the bis-esters of Examples 6 and 7 and their compounds with copper have excellent solubility even in a concentrated solution in a very slightly polar solvent with a low content of aromatic hydrocarbons.

EXAMPLE 9 This example demonstrates that the preferred products according to the invention remove copper from an aqueous solution with a high chloride ion concentration and transfer it to an aqueous solution with a lower chloride ion concentration, even when the latter solution is already

0 contains copper (usually in the spent electrolyte for maximum efficiency, since usually only a portion of the copper in each phase is electrolyzed through the electrolytic cell).

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It also demonstrates that there is no or very little transfer of iron or acid, even when iron is present in the feed solution at a higher concentration than

copper (as is usually the case during the leaching of ferric chloride).

In addition, it demonstrates the improved characteristics of the preferred products according to the invention in comparison with 2-hexidecyl nicotinate i. product from example 1.

Bis (2-hexyldecyl) pyridine-3,5-dicarboxylic acid ester was obtained by reacting pyridine-3,5-dicarboxylic acid with thionyl chloride and then with 2-hexyldecanol according to the method of examples 2-8. This ester was not distilled, but the toluene solution of the crude product was shaken with a 2 molar aqueous solution of sodium hydroxide and then with water and toluene was distilled, resulting in a product in the form of an oil with a purity of 93.5%, as determined by titration the use of perchloric acid in a solution of acetic acid / acetic anhydride.

The other ligands used in this example are the products of examples 1, 2, 5, 6, and 8. The boiling point ranges and estimated purity of these liquids are listed in Table. 2. The characteristics of these fluids are compared with the characteristics of 2-g, xyldecyl nicotinate, which is the product of Comparative Example 1.

Each liquid was obtained in the form of a solution with a concentration of 0.5 M in a hydrocarbon solvent. For the product of Example 1, ESCAID 100 was used. For other liquids, except for the product from Comparative Example A, where AROMASOL H was used, a solvent with a very high content of aromatic hydrocarbons, Solvesso 150 was used.

The leach liquor (L), typical of those obtained by leaching chalcopyrite with a solution of ferric chloride (3), was prepared by diluting copper chloride, ferric chloride and hydrochloric acid in water to obtain a solution containing 25 g / l C, 84 , 3 g / l Fe and 10.9 g / l HCI, which had a total chloride concentration of 4.2 mol.

In turn, each ligand was loaded by shaking for 1 with an equal volume of leach (L) from leaching and then separated and further loaded by shaking with a fresh portion of leach (L) from leaching in a similar way. The liquid solution obtained the characteristics of the added compounds of copper ligand chloride with the acquisition of a dark blue color. Then the ligand solution was separated and desorbed by

shake with an equal volume of aqueous stripping solution S. The blue color of the organic solution faded in accordance with the transfer of copper into solution S.

Then, the loaded stripping solution was separated and analyzed for copper, iron, and acid (as HCI). The amounts of copper, iron, and acid that were transferred to the solution by this

method listed in Table. 2

From the examples it is clear that using the proposed extractant, it is possible to achieve effective recovery of copper from solutions that were obtained from leaching copper-containing sulfide ore with an aqueous solution of ferric chloride (3).

In comparison with the known methods, the proposed procedure is simpler, since at the extraction stage the solvent in the system does not ion exchange, i.e. extraction of copper chloride (neutral substance) into the organic phase is achieved, therefore, it is possible to replace the stage of distillation of HCI, the stage of electrolysis of HCI and

the stage of hydrogen reduction by one stage of electrolysis of copper chloride.

Claims (2)

Claims 1. A method for extracting copper from aqueous solutions containing a chlorine ion, including treating them with an extractant and re-extracting copper, characterized in that, in order to simplify the process, substituted pyridine of the general formula is used as an extractant. os cox PG where: X is the group ORi, N RI is branched chain alkyl groups, and both RI groups contain together 16-32 carbon atoms. 2. The method of clause 1. distinguishing those that use pyridine, containing as the group R - mixed isomer Octyl 3 way pop. 1, different topics that use pyridine containing as the group RI, diisobutylcarbinyl. 4 Way to pop, 1, different topics that use pyridine containing as a group RI mixed isomer isodecyl. 5. The method according to claim 1. characterized in that pyridine is used containing as an RI group, the tridecyl mixed isomer. 6. A method according to claim 1. Distinguishing itself by the use of pyridine containing as the group RI 2-hexyl decyl. Table 1  Isononanol mixed isomer mixed stream of octene. was obtained by hydroforming table 2