RU2366737C2 - Method of extracting copper out of water solution - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: disclosed method consists in extraction of copper by treating extractant with water solution; ketoximes or aldoximes or their mixtures in organic solvent are used as extractant. Before extracting initial water solution is treated with calcium or magnesium hydroxide or potassium or soda carbonate with sedimentation of hydroxide, carbonate or copper hydroxocarbonate. Clarified liquid phase is separated, thus condensed copper containing pulp is produced, which is subject to extraction at maintaining ratio (in mol.) copper: extractant = 1:(2.0-4.0). Upon extraction of water phase, depleted copper is separated, while produced copper containing organic phase is treated with weak solution of mineral acid of concentration equal to 0.05-0.3 mole/dm3. Further, water phase, containing iron, impurities and partially copper is separated; while copper is extracted out of organic phase by known methods. ^ EFFECT: several times reduced volume of primary water solutions subject to extracting treatment and reduced cost for clarifying water solvent solutions from products of extractant and thinner decomposition. ^ 4 cl, 4 ex

Description

The present invention relates to the field of technology for the extraction of non-ferrous metals from ore solutions. As is known, oximes are widely used as extractants for the extraction of copper from sulfate solutions [1, 2]. Initially, ketoximes were used to extract copper from aqueous solutions with a pH of more than 2. Further studies led to the creation of aldoximes with the ability to extract copper from relatively acidic solutions with pH 1.5 or lower [3, 4]. However, in either case, hydrogen ions released due to the exchange reaction reduce the extraction ability and limit the capabilities of this extraction method.

The closest in technical solution and the achieved result is the copper extraction method described in the patent [5]. An aqueous solution containing copper sulfate concentration of 2-5 g / DM ³ is mixed with an organic phase containing a solution of extractant in a diluent. The extraction is carried out at 1-3 steps, sequentially in countercurrent processing the aqueous phase. In the raffinate solution, the copper content does not exceed 0.1-0.2 g / DM ³ . The obtained organic phase containing copper is washed with a weak solution of sulfuric acid and copper is reextracted with a solution of sulfuric acid of a higher concentration of 150-180 g / dm ³ . Considering the millions of tons of copper produced, it is possible to imagine the volume (1000-1500 m ³ / h at an average copper plant) of wastewater discharged containing a water-soluble extractant, diluent impurities and extractant degradation products. In accordance with modern environmental requirements, such waters must be purified from organic impurities. The cleaning costs are so high that they make up a significant part of the cost of copper.

The authors of the application set the task to reduce several times the volume of aqueous solutions subjected to extraction processing, which will significantly reduce the cost of purifying aqueous raffinate solutions from water-soluble organics. The goal is achieved by the implementation of the following sequence of operations. The initial copper-containing solution is treated with a reducing agent (for example, metallic iron) to reduce Fe ⁺³ to Fe ⁺² . The resulting aqueous solution is treated with calcium or magnesium hydroxide or potassium or sodium carbonate to obtain hydroxocarbonate, or carbonate, or copper hydroxide and the liquid phase is separated to obtain pulp (for example, by cohesion). When precipitating hydroxocarbonate, or carbonate, or copper hydroxide, the pH of the pulp is maintained at 6.0-7.0. Then the pulp is treated with a solution of extractant in a diluent, the aqueous phase depleted in copper is separated, and the resulting organic phase is treated with a weak solution of mineral acid, the aqueous phase containing iron, impurities of other elements and partially copper are separated, and it is sent to the fresh organic phase for processing. The ratio of copper in the pulp and extractant (in mol.) Maintain equal copper: extractant = 1: 2.0-4.0. Ketoximes, aldoximes or mixtures thereof with an extractant content in a diluent of 5-50% (vol.) Are used as an extractant. The organic phase containing copper is mixed with a weak solution of mineral acid (the concentration of mineral acid in the aqueous solution is maintained at 0.05-0.3 mol / dm ³ ), the resulting aqueous phase is combined with the aqueous phase after the first contact and treated with a fresh organic phase, which is sent to the head of the process for processing copper-containing pulp. The recommended ratio (in mol.) Copper: extractant = 1: 2.0-4.0 is explained by stoichiometric parameters and the need for maximum copper recovery. When the ratio decreases to less than 1.8-1.9, precipitation of copper carbonates remains in the aqueous phase, which is undesirable. Recommended pH ranges for copper deposition are derived from the physicochemical properties of copper ions.

The positive effect is to reduce several times the volume subjected to extraction processing of the initial aqueous solutions. Due to this, the cost of cleaning aqueous raffinate solutions from the products of the destruction of the extractant and diluent is significantly reduced.

Example 1

The ore of the Udokan deposit was treated with sulfuric acid to extract copper. Iron was reduced to a divalent state. Sodium carbonate was added to 100 cm ^{3 of the} obtained sulfate solution containing 2.36 g / dm ^{3 of} copper and 0.158 g / dm ^{3 of} iron until a pH of 6.2 was reached. The clarified part was separated from the condensed pulp. To the resulting pulp (pulp volume 12 cm ³ ) was added with stirring 25 ml of a 15% solution of Lix-984N in “Escaid-110” diluent. After separation, the aqueous phase (with pH 7) was separated. The copper content in the aqueous phase is 28.8 mg / dm ³ . The resulting organic phase was treated with 5 cm ^{3 of} 0.2 mol / DM ³ sulfuric acid with stirring. After delamination in the aqueous phase, 1.24 g / dm ^{3 of} copper was detected. Such a solution was sent to the first stage of processing for additional recovery of copper. Direct extraction of copper into the organic phase at the stage of extraction from the pulp is 99.86%. During washing, 5.25% of copper is returned to the after-extraction stage. Total copper recovery exceeds 99.8%. The volume of an aqueous solution containing organic impurities decreased by 5.9 times.

Example 2

To 20 cm ^{3 of the} solution obtained by treating the udokan ore with sulfuric acid, but without iron reduction, sodium carbonate was added to pH 6.5, the condensed part of the pulp (5 ml) was separated and intensively mixed with 3 cm ^{3 of} 15% Lix-984N in the diluent "Escide". Found in the aqueous phase: copper - 24.9 mg / dm ³ , iron 34.3 mg / dm ³ , the pH of the aqueous phase - 4.5. The extraction of copper in the organic phase is 99.74%, iron - 94.6%. The result indicates the need for a preliminary transfer of iron to a divalent state. The organic phase was washed with 0.1 mol / dm ^{3 of a} solution of sulfuric acid with a phase ratio Vorg: V water = 4: 1. The volume of wastewater with organic impurities decreased by 3.3 times.

Example 3

Sodium carbonate was added to a pH of 6.9 to 30 cm ^{3 of the} solution obtained by treating sulfuric acid with the ore of the Udokan deposit, the condensed part of the pulp (5 cm ³ ) was separated and intensively mixed with 5 cm ^{3 of} 15% Lix-984N in the Escid diluent ". In the aqueous phase, 35.5 mg / dm ^{3 of} copper was detected, and the pH of the aqueous phase was 6.3. Extraction of copper in the organic phase is 99.63%. The organic phase was washed with 0.1 mol / dm ^{3 of a} solution of sulfuric acid with a phase ratio Vorg: V water = 4: 1. The volume of wastewater with organic impurities decreased by 5 times.

Example 4

Sodium carbonate was added to a pH of 7.0 to 40 cm ^{3 of the} solution obtained by treating sulfuric acid with the ore of the Udokan deposit, the condensed part of the pulp (5 ml) was separated and intensively mixed with 6 cm ^{3 of} 15% Lix-964N in the Escaid diluent . In the aqueous phase, a gray precipitate forms, the pH of the aqueous phase is 6.5, the copper content is 78.5 mg / dm ³ . The extraction of copper in the organic phase is 99.17%. The organic phase was washed with 0.1 mol / dm ^{3 of a} solution of sulfuric acid with a phase ratio Vorg: V water = 4: 1. The volume of wastewater with organic impurities decreased by 6.4 times. The solutions from the first treatment are mixed with the solution from washing the organic phase, the pH is adjusted to 2-3 and treated with a fresh stream of extractant in the usual mode, returning the resulting organic phase to extract copper from the pulp. The positive effect is to reduce the volume of processed products. For dilute ore solutions, the volume can be reduced by 20-30 times, respectively, the flow of the organic phase and the volume of extraction equipment are reduced. In addition, the working capacity of the extractant increases (the equilibrium pH of the aqueous phase is 3-7, not 1-2), which, accordingly, increases the productivity of the process.

LITERATURE

1. Kordosky G.A. "Copper recovery using leach (solvent extraction) eiectrowinning technology. Forty years of innovation, 2.2 million tonnes of copper annually ”, ISEC-2002, Cape Town, March 17-21, 2002, p.853-862.

2. Jiaoyong Y. “Application of the two types of commercial extractants in China”, ISEC-2002, Cape Town, 03.17-21.2002, p.1014-1020.

3. Kordoski G.A. "Solvent extraction method." Application No. 2005109425, dated 08/06/2003, by class. C22B 3/04.

4. Soderstrom M.D. "Composition and method for solvent extraction of metals using aldoximes and ketoximes." Application No. 2005135644, dated 04.10.2006, according to class C22B 3/006.

5. K.V. Kiselev "Theoretical and technological foundations of hydrometallurgical processing of copper ores of the Udokan deposit." Auth. cand diss. Novokuznetsk, 2005, pp. 12-14.

Claims (4)

1. A method of extracting copper from an aqueous solution, including extraction by treatment with an extractant solution, which uses ketoximes or aldoximes, or mixtures thereof in an organic diluent, characterized in that before extraction the initial aqueous solution is treated with calcium or magnesium hydroxide or potassium or sodium carbonate with by precipitation of copper hydroxide, carbonate or hydroxocarbonate, the clarified liquid phase is separated off to obtain a thickened copper-containing pulp, and the resulting thickened pulp is subjected to extraction by Maintaining the ratio, mol .: copper: extractant = 1: (2.0-4.0), the aqueous phase depleted in copper is separated, the obtained copper-containing organic phase is treated with a weak solution of mineral acid with a concentration of 0.05-0.3 mol / dm ³ , the aqueous phase containing iron, impurities and partially copper is separated, and copper is extracted from the organic phase by known methods. 2. The method according to claim 1, characterized in that for extraction using a solution containing 5-50 vol.% Extractant in an organic diluent. 3. The method according to claim 1, characterized in that during precipitation of the carbonate or hydroxide or hydroxocarbonate of copper, the pH of the pulp is maintained at 6.0-7.0. 4. The method according to claim 1, characterized in that after processing the copper-containing organic phase with a weak solution of mineral acid, the resulting aqueous phase is treated with a fresh stream of extractant, and the resulting organic phase is sent to the head of the process for the extraction of copper from copper-containing pulp.