RU2226559C2 - Copper-containing waste processing method - Google Patents

Abstract

FIELD: nonferrous metallurgy. SUBSTANCE: invention provides method for integrated processing of copper-containing waste to give a series of commercial products. Method comprises treatment of initial raw material with sulfuric acid in presence of nitric acid in cementation of copper metal from solution to give initial raw material. According to invention, 15-25% sulfuric acid and 30-45% nitric acid are used at their ratio (8-12):1 at 85-95 C. Acids are added at least once when initial raw material is loaded, resulting solution is aged until gas formation ceased, and 0.5% solution of polyacrylamide is added at stirring, after which solution is further aged for 5-6 h to give suspension, which is then liberated from precipitate and resulting solution is subjected to electrochemical extraction of copper at anodic density no higher than 450 A/sq.m and temperature 30-60 C until concentration of copper in solution is below 5 g/l. Worked-out electrolyte is passed through initial raw material, while retaining it to achieve concentration of copper in solution below 5 mg/l and concentration of residual free sulfuric acid 0.020-0.005%. Copperdepleted solution is further passed through aminocarboxylic groups-containing ion-exchange resin at 18 to 75 C. EFFECT: increased completeness of processing of anode precipitate obtained as high-purity aluminum production waste. 2 ex

Description

The invention relates to the integrated processing of copper-containing waste with the receipt of a number of marketable products.

There is a known method of electrolytic refining of aluminum by the three-layer method (RF patent No. 2092591, IPC C 22 B 7/00, 1997), which allows the disposal of waste alloys of the aluminum-copper-copper type, which are secondary resources of mechanical engineering waste. The method is based on conducting electrolysis with loading of an aluminum-copper-tin alloy as an anode alloy by periodically removing aluminum and an anodic alloy enriched in tin and copper.

The known method allows for the disposal of waste aluminum-copper-tin alloy with almost no loss to extract aluminum and tin, but it cannot be used in the processing of copper-containing waste, in particular, waste from the production of high-purity aluminum, which along with aluminum contain sufficient amounts of iron, silicon, gallium and a number of other elements.

A known method of processing copper-containing waste, which includes processing the source material with a solution of sulfuric acid in the presence of nitric acid and subsequent cementation of copper from the solution into the feedstock (US patent No. 3933478, IPC C 22 B 7/00, 1976). The method allows to obtain copper from copper-containing waste, preferably containing iron and zinc, by treating the starting material with a mixture of sulfuric and nitric acids, after which the dissolved copper is cemented from the solution by reaction with iron.

The known method can be used for the processing of copper-containing wastes containing zinc and iron, but it is not suitable for the processing of copper-containing wastes, in particular, waste from the production of high-purity aluminum, which along with aluminum contain sufficient amounts of iron, silicon, gallium and a number of other elements.

Thus, the authors were faced with the task of developing a method for processing copper-containing wastes, in particular wastes from the production of high-purity aluminum, which along with aluminum contain sufficient amounts of iron, silicon, gallium, and a number of other elements.

The problem is solved in the proposed method for the processing of copper-containing waste, including processing the feedstock with sulfuric acid in the presence of nitric acid and cementing metallic copper from a solution to the feedstock, in which the portioned feed is treated with 15-25% sulfuric acid in the presence of 30-45 % nitric acid with their ratio of НNО ₃ : Н ₂ SO ₄ = 1: 8-12 and at a temperature of 85-95 ° С, adding acids after loading the raw materials at least once, the solution is kept until gas evolution ceases, after which it is introduced A 0.5% solution of polyacrylamide with stirring, kept for 5-6 hours, the resulting suspension is separated from the precipitate and conduct electrochemical extraction of copper from the resulting solution at an anode current density of not higher than 450 A / m ² , a temperature of 30-60 ° C to obtain a copper concentration in the solution below 5 g / l, the spent electrolyte is passed through the feedstock with an extract to obtain a copper concentration in the solution below 5 mg / l, and the concentration of residual sulfuric acid free is 0.020-0.005%, then the copper-depleted solution is passed through ion exchange nnuyu resin containing aminocarboxylic groups at a temperature of 18-75 ° C.

Currently, from the patent and scientific literature there is no known method for processing copper-containing waste, in which portion-loaded feedstock is treated with acids of a certain concentration in the claimed range of ratios, and acids can be added repeatedly as necessary, then the insoluble part is coagulated by adding a solution of polyacrylamide , then the resulting suspension is separated from the precipitate and electrochemical extraction of copper from the resulting solution is carried out in the claimed conditions and then the spent electrolyte is passed through the feedstock until a certain concentration of copper and free sulfuric acid is obtained, and then the copper-depleted solution is passed through an ion-exchange resin under the claimed conditions.

The proposed method for processing copper-containing wastes allows for complex processing of the anode deposit (the so-called "copper deposit"), which is a waste from the production of high-purity aluminum, with the production of a number of marketable products: copper metal powder; a solution of gallium sulfate, which can be used, in particular, to obtain metallic gallium by known methods; inorganic coagulant for water and wastewater treatment.

The proposed method for processing copper-containing waste can be carried out as follows. In a reactor equipped with a jacket and a reflux condenser, a 15-25% solution of sulfuric acid is fed. Then, from the container into the hatch of the reactor, an anode deposit containing aluminum 62.14-46.31, crushed to a size of not more than 63 microns is loaded in portions at intervals of 10-15 minutes; copper 51.61-6.55; iron 36.54-0.42; silicon 13.10-0.75; gallium 0.59-0.23 and other impurities up to 100%. In the process of dissolution of the anode deposit, self-heating of the solution is possible. When the temperature in the reactor reaches 80 ° C, the supply of cooling water from the reflux condenser to the jacket of the reactor is turned on and the temperature of the reaction mixture is controlled with it to be in the range of 85-95 ° C. If the temperature of self-heating does not reach the specified level, steam is supplied to the reactor jacket and the solution is heated to a temperature of 85-95 ° C. After loading the entire batch of sludge into the reactor, a 30-45% solution of nitric acid is fed with a thin stream, observing the ratio between sulfuric and nitric acids equal to HNO ₃ : H ₂ SO ₄ = 1: 8-12. After supplying nitric acid, cooling water is supplied to the reactor jacket to maintain the temperature of the solution in the desired range. The solution is kept for several hours and, if necessary (if the precipitate is not completely dissolved), again a 15-25% solution of sulfuric acid is fed, and then a 30-45% solution of nitric acid, observing their specific ratio, and again kept solution. The complete dissolution of the precipitate is judged by the complete cessation of gas evolution. If necessary, for the complete dissolution of the precipitate, the supply of acids can be performed as many times as necessary. After gas evolution ceases, the stirrer is turned on and a 0.5% polyacrylamide solution is introduced into the reactor and stirred while maintaining the temperature in the same range of 85-95 ° C by supplying steam to the reactor jacket, then stirring and steam are stopped, the solution is kept for 5-6 hours. The resulting suspension is separated from the precipitate, for example, by filtration through a suction filter, the resulting solution is poured into the electrolyzer with compressed air and electrochemical extraction of copper is carried out at an anode current density of not higher than 450 A / m ² . The electrolyzer is supplied with direct current from a rectifier. Through the tires simultaneously with the filling of the electrolyzer, the anode cassettes are filled with a solution of sulfuric acid with a concentration of 100 g / l. In the process of electrolysis, the temperature and concentration of copper are controlled. The temperature is maintained in the range of 30-60 ° C. To cool the electrolyte in the coil, which is equipped with the electrolyzer, serves cooling water. At the initial moment after turning on the rectifier, a current of 8-10 kA is set. Samples for copper are taken every 3 hours, when the copper concentration reaches 16-18 g / l, the current is reduced to 6.5-6.7 kA. Upon reaching a copper concentration of 6-7 g / l, control of the copper content is performed every hour. When the concentration reaches below 5 g / l, the rectifier is turned off and the electrolysis is completed. Copper powder with a part of the electrolyte is discharged from the electrolyzer to a suction filter, washed first with a solution of sulfuric acid, and then with water and stored in plastic containers. The spent electrolyte is squeezed by compressed air into the loading port of the reactor, where the feedstock — the crushed anode precipitate — is preloaded. The electrolyte is passed through the feedstock with aging to obtain a copper concentration in the solution below 5 mg / L, and the concentration of residual sulfuric free acid to 0.020-0.005%. The process is carried out at a temperature not exceeding 90 ° C. If the temperature is higher than indicated, cooling water is supplied to the reactor jacket. After 2-3 hours, the concentration of free sulfuric acid is controlled, if it exceeds 0.020%, steam is fed into the jacket of the reactor and the concentration of free sulfuric acid is again controlled. When the concentration of free sulfuric acid in the solution reaches 0.020-0.005%, and the copper concentration is below 5 mg / l, the precipitate is left in the reactor and the copper-depleted solution is passed through an ion-exchange resin containing aminocarboxyl groups at a temperature of 18-75 ° С .

The proposed method for processing copper-containing waste can be carried out only subject to the values of all process parameters in the claimed intervals. The bulk of the precipitate is barium and calcium sulfates, aluminum and iron (III) oxides, metallic copper and silicon in the form of silicic acid, oxide and metallic silicon salts. When using sulfuric acid with a concentration below 15%, it becomes impossible to dissolve aluminum, iron and silicon from the anode deposit, which slows down and then completely stops the dissolution process. When using sulfuric acid with a concentration above 25%, a strong self-heating of the solution is observed, which can lead to foaming and a transition to an uncontrolled reaction. Conducting the process in the presence of nitric acid with a concentration below 30% leads to the formation of a large amount of nitrate ion, polluting both the electrolyte for electrolysis and the coagulant solution, and at a concentration above 45% leads to the intensive formation of nitrogen oxides. A certain ratio of acids due to the following reasons. When the ratio of nitric and sulfuric acids is less than 1: 8, there is a decrease in the rate of dissolution of cemented copper from the surface of the anode deposit. When the acid ratio is more than 1:12, there is an increase in the emission of nitrogen oxides into the atmosphere and the accumulation of excess nitrate ions in the solution. The exposure for 5-6 hours after the introduction of a 0.5% solution of polyacrylamide is due to the following: an exposure of less than 5 hours does not completely remove the silicon compounds from the solution, and exposure for more than 6 hours is impractical because, according to chemical analysis, a six-hour exposure provides a complete transition insoluble compounds in the sludge. Carrying out the electrochemical extraction of copper at an anodic current density above 450 A / m ^{2 is} impractical, since the degree of copper extraction remains at the same level (90%), and the energy consumption increases unjustifiably. Conducting the extraction process at a temperature below 30 ° C leads to a decrease in the degree of extraction of copper to 80%, and when the temperature rises above 60 ° C, a strong heating of the electrolyte is observed and it becomes possible to spray it. When passing the spent electrolyte through the feedstock, obtaining a concentration of residual sulfuric free acid in the range of 0.020-0.005% is necessary to obtain a solution pH in the range of 2.0-2.5; which provides a more complete extraction of gallium in sorbate.

The proposed method is illustrated by the following examples:

Example 1. In a reactor equipped with a jacket and a reflux condenser, serves 4.5 m ^{3 of a} 15% solution of sulfuric acid. Then from the container into the hatch of the reactor in portions of 15 kg with an interval of 10 minutes load 500 kg of crushed anode sediment containing (wt.%): Aluminum 55,43; copper 27.56; iron 10.68; silicon 5.10; gallium 0.54 and other impurities - up to 100. When the temperature in the reactor reaches 90 ° C, turn on the supply of cooling water from the reflux condenser to the jacket of the reactor and use it to set the temperature of the reaction mixture to 85 ° C, while the reaction mass is mixed. After loading the entire batch of sludge into the reactor, a 30% solution of nitric acid is fed with a fine stream, observing the ratio between sulfuric and nitric acids equal to HNO ₃ : H ₂ SO ₄ = 1: 8. After the nitric acid has been supplied, cooling water is supplied to the reactor jacket to maintain the desired temperature of the solution. The solution was incubated for 3 hours, after which the gas evolution ceased, which means complete dissolution of the precipitate. After gas evolution ceases, 30 L of a 0.5% polyacrylamide solution is introduced into the reactor and stirred while maintaining the temperature at 85 ° C by feeding steam into the jacket of the reactor, then stirring and steam are stopped, the solution is kept for 5 hours. The resulting suspension is separated from the precipitate by filtration through a suction filter, the resulting solution is pressed into the electrolyzer with compressed air and electrochemical extraction of copper is carried out at an anode current density of 400 A / m ² . The electrolyzer is supplied with direct current from a rectifier VAK 12500-12. Through the tires simultaneously with the filling of the electrolyzer, the anode cassettes are filled with a solution of sulfuric acid with a concentration of 100 g / l. In the process of electrolysis, the temperature and concentration of copper are controlled. The temperature is maintained at 30 ° C. To cool the electrolyte in the coil, which is equipped with the electrolyzer, serves cooling water. At the initial moment after turning on the rectifier, a current of 8 kA is set. Samples for copper are taken every 3 hours; when copper concentration reaches 16 g / l, the current is reduced to 6.5 kA. Upon reaching a copper concentration of 6-7 g / l, control of the copper content is performed every hour. After 16 hours, the copper concentration is 4.8 g / l, the rectifier is turned off and the electrolysis is completed. Copper powder with a part of the electrolyte is discharged from the electrolyzer to a suction filter, washed first with a solution of sulfuric acid, and then with water and stored in plastic containers. 110 kg of copper metal powder are obtained. 5.3 m ^{3 of the} spent electrolyte is pushed with compressed air into the loading port of the reactor, where the feedstock is pre-loaded - 500 kg of crushed anode deposit. The electrolyte is passed through the feed for 2 hours at a temperature of 85 ° C. After 2 hours, the concentration of free sulfuric acid is controlled, which is 0.020%, the copper concentration is below 5 mg / l, the precipitate is left in the reactor, and the copper-depleted solution is passed through an ion-exchange resin containing amine carboxyl groups at a temperature of 18 ° C. . Get 480 l of sorbate - gallium sulfate, which can be sent for processing by lime methods to obtain metallic gallium. In addition, 5.3 cubic meters of a solution of aluminum and iron (II) sulfates are obtained, which is used as an inorganic coagulant for the treatment of alkaline wastewater.

Example 2. In a reactor equipped with a jacket and a reflux condenser, 4.5 m ^{3 of a} 25% solution of sulfuric acid are fed. Then from the container into the hatch of the reactor in portions of 20 kg with an interval of 15 minutes load 500 kg of crushed anode sediment containing (wt.%): Aluminum 56.77; copper 29.48; iron 7.38; silicon 5.49; gallium 0.39 and other impurities - up to 100. When the temperature in the reactor reaches above 95 ° C, turn on the supply of cooling water from the reflux condenser to the jacket of the reactor and use it to set the temperature of the reaction mixture to 95 ° C. After loading the entire batch of sludge into the reactor, a 45% solution of nitric acid is fed with a fine stream, observing the ratio between sulfuric and nitric acids equal to НNO ₃ : H ₂ SO ₄ = 1: 12. After the nitric acid has been supplied, cooling water is supplied to the reactor jacket to maintain the desired temperature of the solution. The solution was kept for 3 hours, then, since violent gas evolution continued to be observed, another 240 dm ^{3 of} sulfuric acid was fed from the measuring device with a fine stream and then 20 dm ^{3 of} nitric acid, the reaction mixture was kept for another 3 hours, after which the gas evolution ceased, which means complete dissolution of the precipitate. After gas evolution ceases, a stirrer is turned on and a 30 L of a 0.5% polyacrylamide solution is introduced into the reactor and stirred while maintaining the temperature at 95 ° C by feeding steam into the reactor jacket, then stirring and steam supply are stopped, the solution is kept for 6 hours. the suspension is separated from the precipitate by filtration through a suction filter, the resulting solution is pressed into the electrolyzer with compressed air and electrochemical extraction of copper is carried out at an anode current density of 450 A / m ² . The electrolyzer is supplied with direct current from a rectifier VAK 12500-12. Through the tires simultaneously with the filling of the electrolyzer, the anode cassettes are filled with a solution of sulfuric acid with a concentration of 100 g / l. In the process of electrolysis, the temperature and concentration of copper are controlled. The temperature is maintained at 60 ° C. To cool the electrolyte in the coil, which is equipped with the electrolyzer, serves cooling water. At the initial moment after turning on the rectifier, a current of 10 kA is set. Samples for copper are taken every 3 hours; when copper concentration reaches 16 g / l, the current is reduced to 6.7 kA. Upon reaching a copper concentration of 6-7 g / l, control of the copper content is performed every hour. After 12 hours, the copper concentration is 5.0 g / l, the rectifier is turned off and the electrolysis is completed. Copper powder with a part of the electrolyte is discharged from the electrolyzer to a suction filter, washed first with a solution of sulfuric acid, and then with water and stored in plastic containers. 120 kg of copper metal powder are obtained. 5.5 m ^{3 of the} spent electrolyte is pushed with compressed air into the loading port of the reactor, where the feedstock is pre-loaded - 500 kg of crushed anode deposit. The electrolyte is passed through the feed for 2 hours at a temperature of 95 ° C. After 2 h, the concentration of free sulfuric acid, which is 0.005%, is controlled, while the copper concentration is below 5 mg / l, the precipitate is left in the reactor, and the copper-depleted solution is passed through an ion-exchange resin containing carboxyamine-functional groups at a temperature of 75 ° C. Get 350 l of sorbate - gallium sulfate, which can be sent for processing by lime methods to obtain metallic gallium. In addition, 5.8 cubic meters of a solution of aluminum and iron sulfates are obtained, which is used as an inorganic coagulant for the treatment of alkaline wastewater.

Thus, the proposed method for processing copper-containing waste allows complex processing of the anode deposit - waste from the production of high-purity aluminum to produce a number of marketable products.

Claims (1)

A method of processing copper-containing waste, including processing the feedstock with sulfuric acid in the presence of nitric acid and cementing metallic copper from a solution to the feedstock, characterized in that the feedstock is portioned and treated with 15-25% sulfuric acid in the presence of 30-45% nitric acid at their ratio of NHO ₃ : H ₂ SO ₄ = 1: 8 ÷ 12 and at a temperature of 85-95 ° C, adding acid after loading the raw material at least once, maintain the solution until gas evolution ceases, after which 0.5 % solution of polyacrylamide upon ne the mixing is allowed to stand for 5-6 hours, the resulting suspension is separated from the sludge and conducted electrochemical copper extraction from the obtained solution at anode current densities not higher than 450 A / m ² and a temperature of 30-60 ° C until the copper concentration in the solution below 5 g / l, spent electrolyte is passed through the feedstock with an extract to obtain a copper concentration in the solution below 5 mg / l, and the concentration of residual sulfuric free acid is 0.020-0.005%, then the copper-depleted solution is passed through an ion exchange resin containing aminocarboxy ln groups at a temperature of 18-75 ° C.