RU2075547C1 - Method of electrolytic regeneration of copper from sulfate electrolytes - Google Patents

Abstract

FIELD: nonferrous metallurgy, particular, electrolytic precipitation of copper from sulfate solutions with insoluble anodes. SUBSTANCE: method of electrolytic regeneration of copper from sulfate electrolytes consists in formation on the electrolyte surface of protecting layer of foam by introduction into electrolyte of surfactant. Novelty consists in that foaming surfactant is used in form of alkyl sulfates on alcohols of fraction C₁₀-C₁₃ of general formula C_nH_2n+1OSO₃Na where n=10-13 in the amount of 0.050-0.100 g/l. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to the field of non-ferrous metallurgy, in particular to the electrolytic deposition of copper from sulfate solutions with insoluble anodes. During the electrolysis of copper with insoluble anodes, oxygen is released on the anode, and hydrogen is released on the cathode at the end of regeneration along with copper. Gases and vapors formed in the process of copper regeneration in the form of bubbles are released from the bath mirror into the atmosphere, entraining electrolyte drops (aerosols).

 The content of harmful impurities, such as copper and sulfuric acid, exceeds the maximum permissible designs by tens of times, and nickel by hundreds of times.

 It is known to use organofluorine aliphatic surfactants that foam on the surface of an electrolyte to suppress the release of "acid mist" in the electrolytic production of copper (US Pat. No. 4,484,990, CL 25/12, publ. 11/27/84). However, such an electrolyte cannot be used due to the toxicity of organofluorine compounds.

 The effect of nonionic surfactants OP-7, OP-10, OS-20, cetyl and polyvinyl alcohol, sodium oleate, and oximes 0-18 on the release of aerosols during copper electrodeposition is known (T.V. Efimov, I.V. Zauzolkov. O the influence of surfactants on the evaporation of electrolyte during the electrorefining of copper. Report "Uniromed", Sverdlovsk, 1991). However, these additives reduce aerosol emissions by only 40-60% and degrade copper quality.

It is known to use polyelectrolytes with a molecular weight of 10 ⁴ to 10 ⁷ (derivatives of styrene sulfonic acid, vinyl sulfonic acid, vinylphosphonic acid, 2-acrylaminomethylpropanoic sulfonic acid or their salts) to eliminate acid fog during the electrolytic production of metal, in particular copper (UK application N2250515, class C25C 1/1 00, publ. 06/10/92).

 However, the use of polymers as additives in the electrolyte requires additional equipment costs for their preliminary preparation before being introduced into the electrolysis bath.

 It is known to use as a foaming additive to obtain a protective layer of licorice root extract during the electrical regeneration of copper from a sulfide solution (Technological instruction for the production of electrolyte copper NTI 48-0404-07-03-91, the Severonickel plant).

 However, the use of licorice root extract in the process of electrodeposition of copper does not allow reaching the MPC level. The concentration of nickel in the atmosphere of the workshop exceeds MPC by several orders of magnitude, the concentration of sulfuric acid exceeds MPC by 4–5 times.

 The closest analogue of the proposed method is a method of electrolytic regeneration of copper from sulfate electrolytes according to as USSR N579348, class C25C 1/12.

 The disadvantage of the closest analogue is that the use of sulfur-containing surface-active substances in it, such as the claimed reagent, significantly increases the sulfur content in the finished product of cathode copper, thereby reducing its markability, which is confirmed by the theses of the meeting "Improving the technology and improving the quality of copper products sub-sectors ", Sverdlovsk, 1987, p. 21. In addition, thiourea is an imported product purchased for currency, which increases its cost, the condensation product of thiourea and fatty acid aminoamides has a high consumption, 2 times more than in the proposed method.

 Using the known method allows to reduce the release of aerosols due to electrolyte losses by only 5 6 times.

The claimed method consists in the fact that a protective layer of foam is formed on the surface of the electrolyte due to the introduction of sodium alkyl sulfates on the alcohols of the fraction C ₁₀ C ₁₃ in the amount of 0.050 0.100 g / l as a surfactant.

 Having a high foaming property, this additive, under the action of gas bubbles released during electrolysis, forms a dense layer of foam on the surface of the bath mirror, which delays the release of aerosols into the atmosphere.

Alkyl sulfate anionic surfactants of the general formula:
C _n H _{2n + 1} OSO ₃ Na,
where n 10 13 (TU 38.407257-84) is a paste obtained by sulfating synthetic primary fatty alcohols of the fraction C ₁₀ - C _{13 with} sulfuric or chlorosulfonic acid. Color from white to light yellow, pH of 1% aqueous solution of 8 9.5. The product is low toxic. Belongs to biologically soft (decomposes by 95%). Alkyl sulfates are produced by the domestic industry on a large scale, being the basis of most detergents.

 The main criterion for evaluating the effectiveness of the proposed method is the concentration of copper, Nickel and sulfuric acid in air samples above the surface of the electrolysis bath.

 With a decrease in surfactant concentration of less than 0.050 g / l, foam-free areas of electrolyte are observed. A dense layer of foam appears only at a concentration of 0.050 g / l surfactant. At this concentration, there are no spaces free of foam on the bathtub mirror. Therefore, the lower limit of surfactant concentration is 0.050 g / l.

 An increase in the concentration of surfactants above 0.100 g / l is impractical due to the increase in the height of the foam, which rises to the current leads and forms a hard wash on the cathode rods, which leads to an increase in the labor required to clean the surface of the rods.

 An example implementation of the method.

 The effectiveness of the effects of the addition of alkyl sulfates has been tested in laboratory conditions. In all experiments, an industrial electrolyte was used, g / l: copper sulfate 120, nickel sulfate 75, sulfuric acid 180.

The experiments were carried out in an electrolysis bath with a capacity of 3 liters with a shelter in the form of a box made of organic glass. The cathodes were two titanium matrices with a working surface of 130 cm ² each. As anodes, sheet lead was used. The technological parameters corresponded to the industrial ones: the cathode current density was 280 A / m ² , the anode 290 A / m ² , the temperature of the electrolyte in the bath was 65 ^o C. For each experiment, pure electrolyte was prepared and the calculated amount of surfactant was introduced.

 To take an air sample, a funnel with an AFA-VP-20-1 analytical filter was inserted into a circular hole with a diameter of 70 mm in the end wall of the shelter and tightly mounted on the wall. In the opposite wall of the box, below, a gap was left for free access of air. Using an aspirator, air was drawn through the funnel above the bath mirror at a speed of 20 l / min (rotameter) for 10 20 minutes. The opposite location of the slit and filter made it possible to direct the air flow over the entire surface of the bathtub and capture the aerosols that were released.

 The sample volume was 200,400 liters.

 Analyzes for the determination of copper and nickel were performed by atomic absorption spectrometric, analyzes for the determination of sulfuric acid by nephelometric methods.

 The table shows examples of the implementation of the proposed technical solution.

 Examples 1 to 7.

The copper was regenerated from an electrolyte of the composition, g / l: copper sulfate 120, nickel sulfate 75, sulfuric acid 180. The cathodic current density was 280 A / m ² , the temperature was 65 ^o C. The cathode area was 260 cm ² , the electrolyte volume in the bath was 3 liters . The cathodes are made of sheet titanium, the anodes of sheet lead.

 In each experiment, a certain amount of surfactant was introduced from 0 to 0.110 g / l. 10 minutes after turning on the current, air samples were taken using an aspirator and analyzed for nickel, copper, and sulfuric acid.

 Example 8 (the closest analogue).

 Electric regeneration was carried out under the conditions of examples 1 to 7, but 0.02 g / l of a surfactant mixture was introduced as a foaming additive: penazoline 10-16D 0.14 g / l, oleic acid aminoethylpiperazide 0.005 g / l, ethoxylated alcohols 0.001 g / l and organosilicon PES-B liquids 0.001 g / l.

 As follows from the data given in the table, the aerosol content in air samples is several times less than in the closest analogue. In the claimed range of additive concentrations, the content of nickel aerosols is reduced by 19 20 times, copper by 13 17 times, sulfuric acid by 18 22 times.

Claims (1)

The method of electrolytic regeneration of copper from sulfate electrolytes, including the formation of a protective layer of foam on the surface of the electrolyte when a surfactant is introduced into it, characterized in that alkyl sulfates on alcohols of the fraction C _{1 0} C _{1 3 of the} general formula C are used as a surfactant _n H _{2 n + 1} OSO ₃ Na, where n 10 13, in an amount of 0.05 0.100 g / l.

Images