RU2693576C2 - Copper electrolytic refining method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to electrolytic refining of copper containing impurities in amount of up to 2 wt. %. Method involves formation of copper anode and electrolytic dissolution of anode in sulphuric acid solution with deposition of cathode copper. Bulk anode is formed out of copper granules with size of 0.5–20.0 mm. Electrolytic dissolving of anode is performed at application of constant anode current with density of 50.0–100.0 A/m² to obtain cathode deposit in form of copper powder. Bulk anode is formed from granules obtained by water granulation of melt of anode copper.

EFFECT: excluding formation of recycled materials in form of anode residues.

1 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of non-ferrous metallurgy, in particular to a method of electrolytic refining of copper from anodes containing lead, nickel, tin, zinc and other impurities.

Currently, the electrolysis of metals is carried out for their purification from impurities and the release of the cathode metal (copper, lead, nickel, etc.) of high purity. Before electrolysis, anodes of a certain quality, configuration, and mass are cast from liquid metal. Electrolysis is carried out at a current density that prevents contamination of the cathode metal due to cataphoretic transfer of suspended particles. To ensure the required quality of the cathode metal, the electrolyte is cleaned from impurities, and the voltage is maintained within the limits that ensure minimal power consumption and high current output.

Recently, a new direction has been developed - electrolysis of granular materials. These techniques can be used for the electrolysis of metal granules. One of the options for obtaining them is a highly gradient cooling of the molten metal by its aqueous granulation. Products of such cooling will be in the form of granules. Compared with cast anode electrolysis, the best performance is achieved by replacing the anode casting operation with metal granulation, reducing the amount of recycled materials — eliminating undissolved anode residues, increasing the electrolyzer performance — large surface of the granules per unit mass of metal.

The known method of electrolytic refining of copper anodes containing impurities, [US Pat. 2152459 Russian Federation, IPC С251 / 12, С22В 15/00, Method of electrolytic refining of copper / Miroevsky G. P., Demidov K.А., Ermakov I.G. et al., applicant and patent holder of JSC

Kola Mining and Metallurgical Company (RU) - №99126663/02; declare 12/16/1999; publ. 07/10/2000, Byul. No. 19-2 S.], including sulfuric acid leaching of metallic copper from secondary copper-containing raw materials with the imposition of a symmetric alternating current of industrial frequency when heated.

The disadvantage of this method is the need to heat the electrolyte to 60 ° C, a relatively low leaching rate, since the mixing only clears the surface of the sludge.

The known method [US Pat. 2559076 Russian Federation, IPC C22B 7/00, Method for utilization of copper-containing wastes / Boltachev AA, Grachev RS, Kiverin V.L. et al., Applicant and Patentee of Leading Research Institute of Chemical Technology OJSC and Chepetsk Mechanical Plant OJSC; declare 04/10/2014; publ. August 10, 2015, Bull. No. 22 - 3 s.] Utilization of copper-containing waste of superconducting materials, including the dissolution of copper by immersing a basket of scrap in a copper-calcium alloy in the process of electrolysis of calcium at a temperature of 650-715 ° C.

The disadvantage of this method is the need to conduct the process at high temperatures, corresponding to the melts of Cu - Ca.

The known method [US Pat. 2578882 Russian Federation, IPC C22B 15/00. / Method of leaching of metallic copper. Lobanov V.G., Mastyugin S.A., Ashikhin V.V. et al., Applicant and Patentee Federal State Autonomous Educational Institution of Higher Professional Education “Ural Federal University named after the first President of Russia B.N. Yeltsin ”(RU) - №2013155426/02; declare 12.12.2013; publ. 03/27/2016, Bull. No. 9 - 5 s.] Leaching of metallic copper from copper-containing materials in a solution of sulfuric acid with the addition of an oxidizing agent when heated and applying alternating current of industrial frequency with insoluble electrodes.

The disadvantage of this method is the low rate of dissolution and the quality of the metal in connection with the uneven composition and size of complex raw materials.

As a prototype, a method of copper refining was chosen [Khudyakov, I.F., Klein, S.E. and others. Metallurgy of copper, nickel and cobalt, V. 1. - M .: Metallurgy, 1977, p. 276-277], which includes the casting of anodes and electrolytic refining in a sulfuric acid solution at a current density of 200-400 A / m ² to obtain copper cathodes on a titanium matrix. After removing the cathode deposit from the matrix, the copper cathodes are sent to remelting to produce copper rod.

The disadvantages of the prototype is a multi-stage, including the casting of anodes, electrolysis, the removal of copper from the matrix and the melting of cathode copper, followed by obtaining rod. In addition, the disadvantages of the method are high costs due to incomplete dissolution of the anodes (up to 30% of the anodic residues are sent to remelting) and failure of the titanium cathode arrays, and there is also a need for strict control of the content of impurities in the anodes to prevent sludge Also, due to their small specific surface area, it becomes necessary to simultaneously involve a significant number of anodes in processing in order to increase productivity, an increase in the number of anodes leads to an increase in the number of baths for the electrolysis of copper occupying large areas.

The technical result of the claimed invention is to simplify the method of electrolytic refining of copper, ensuring the involvement in the processing of copper-containing material with a high content of impurities.

In this case, the inventive method allows to reduce the number of operations (casting of anodes, removal of compact cathode sediment from the matrix), to exclude the formation of working materials in the form of anode residues, to reduce the industrial area occupied by electrolysis baths.

This technical result is achieved by the fact that in the method of electrolytic refining of copper containing impurities in an amount of up to 2 wt. %, including the formation of copper from the anode and electrolytic dissolution of the anode in the sulfuric acid solution with the deposition of cathode copper, according to the invention, form a bulk anode of copper granules with a particle size of 0.5-20.0 mm, while the electrolytic dissolution of the anode is carried out by applying a constant anode current density 50.0-100.0 A / m ² to obtain a cathode sediment in the form of copper powder. In this case, the formation of a bulk anode is carried out from granules obtained by water granulation of anode copper melt.

The invention consists in the formation of the anode of the anode copper to be purified, containing up to 2 wt. % of impurities, with the formation of granules with a particle size of 0.5-20.0 mm and their subsequent electrolysis in an aqueous solution (100 g / dm ³ ) of sulfuric acid to produce electrolytic copper powder in an electrolysis bath. The optimal size of the granules is 0.5–20.0 mm: the size of the granules less than 0.5 mm leads to process inhibition, and more than 20 mm reduces the efficiency of electrolysis due to their incomplete dissolution as a result of the surface passivation by anode sludge.

As a result of cooling of the anode metal with a high speed, nonequilibrium phases are formed, which have an increased reactivity during electrolysis. The granular material has a developed reaction surface, which allows for electrolysis at low current densities (50.0-100.0 A / m ² ). When the current density is below 50.0 A / m ² , the duration of electrolysis increases significantly, as the process speed slows down, and above 100.0 A / m ² , cataphoretic transfer of small particles to the cathode and deterioration of the metal is observed. In addition, due to the developed reaction area increases the performance of electrolysis.

The invention is illustrated in the figure, which shows a schematic diagram of an electrolytic cell.

Examples of the method.

Example 1. The simulation of the process of electrolysis of copper granules was carried out on a laboratory electrolyzer (Fig.), Which is an electrolytic Plexiglas cell with anodic and cathodic chambers, which allow anodic dissolution of bulk material and cathodic deposition of metal powder.

The anode chamber (1) included a current lead (2) —a plate made of platinized titanium, a cathode plate (7) —a plate made of stainless steel fixed in a rigid frame and acting as a cathode matrix. Granulated copper (3) was placed in the near anode space so that the granules adjacent to the current lead form a porous layer. The anode chamber is bounded by a filter cloth (4) to prevent the anode material and cathode sediment from entering the electrolyte (5). The cathode copper powder (6) is released in the cathode chamber (7) also limited by filter cloth to prevent copper powder from entering the electrolyte bulk.

The electrolysis was subjected to copper granules with a size of 0.5-20.0 mm, which contained,%: 98.67 Cu; 0.006 Bi; 0.007 Fe; 0.025 Pb; 0.216 Ni; 0,0151 Zn; 0.005 Sn; 0.079 Sb; 0.101 As; 0.010 Se; 0.84 O; 0,024 S. The process was conducted with the release of electrolytic copper powder at the cathode and the translation of related metals in the sludge. The areas of the current leads of the cathode and the anode were 0.012 m ² each. Before starting, 1 dm of an aqueous solution (98 g / dm ³ ) of sulfuric acid was poured into the electrolyzer. The electrolysis was carried out in a solution of sulfuric acid (100 g / dm ³ ) for 4 hours at current densities of 25.0-100.0 A / m ² (table), calculated as the ratio of the current to the total surface area of the granules and the voltage on the bath 2.5-3.0 V. With a decrease in the current density of less than 50.0 A / m ^{2, the} rate of electrochemical processes decreases, and with an increase above 100 A / m ² , the process of gas formation develops, which leads to a decrease in the current efficiency of copper.

* ^} in all experiments, anode casting and copper removal from the cathode matrix are excluded

According to the data of the table, the highest values of the anode current output and the quality of the cathode copper (the lowest content of impurities) were achieved in the range of current densities of 25-100 A / m ² and with a grain size of 0.5-20.0 mm. Going beyond these parameters leads to impaired process stability, reduced anode current output and contamination of the cathode powder with impurities.

As a result of the experiments, electrolytic copper deposits (table) and an electrolyte containing 12.65-16.95 g / dm ³ Cu ²⁺ were obtained at the cathode. Thus, it was possible to reduce the content of impurities and to obtain precipitations of copper, corresponding to GOST 4960 - 75 mark PMS - 1.

The method allows in comparison with the prototype to eliminate the formation of anodic residues constituting up to 30% by weight of the original anodes, and the operation of casting anodes and cleaning the cathodes. The advantage is the possibility of carrying out the process of electrolysis at low anodic current density due to the developed reaction surface of the granules, which allows to increase the efficiency of electrolysis and the quality of the metal (with the exception of cataphoretic transfer of impurities). In this case, the proposed method allows refining copper containing impurities in an amount up to 2%.

Claims (2)

1. The method of electrolytic refining of copper containing impurities in an amount of up to 2 wt.%, Including the formation of anode from copper and electrolytic dissolution of the anode in a sulfuric acid solution with the deposition of copper cathode, characterized in that the bulk anode is formed from copper granules with a particle size of 0.5-20 , 0 mm, while the electrolytic dissolution of the anode is carried out with the imposition of a constant anode current with a density of 50.0-100.0 A / m ² to obtain a cathode sediment in the form of copper powder. 2. The method according to p. 1, characterized in that the formation of the bulk of the anode are from granules obtained by water granulation of the anode copper melt.

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