China Nonferrous Metallurgy

Abstract:The content of As, Sb and Bi ions in the copper electrolyte is an important factor affecting the quality of the cathode copper. The existing electrolytic deposition method has high power consumption and large copper loss, and the extraction method and ion exchange method have the defect of large liquid volume. In this paper, using SO₂ as reducing agent to reduce As⁵⁺ and Sb⁵⁺, H2O2 as an oxidant to oxidize As³⁺ and Sb³⁺, adjust the valence of arsenic, antimony and bismuth to form precipitated anode slime. An experimental study was carried out to reduce the impurity ions of arsenic, antimony and bismuth in copper electrolyte by counterflow precipitation of sulfur dioxide and hydrogen peroxide. The experiment results show that under certain conditions, the concentration of Sb ions can be reduced by pumping SO₂ into the copper electrolyte alone, but the concentration of arsenic and bismuth ions does not change much; adding H₂O₂ into the copper electrolyte alone can reduce the concentration of arsenic and antimony ions, but it will also reduce the concentration of copper and bismuth ions, which may lead to anode passivation; the best experimental conditions is H₂O₂ added dropwise, the addition amount 4mL/L, the SO₂ inlet concentration 0.125g/L, the stirring speed 250r/min, and the reaction temperature 50℃, under which counterflow precipitation technology can reduce the concentration of arsenic, antimony, bismuth impurity ions in copper electrolyte, and there will be no anode passivation.

Abstract:With the increase in the complexity of copper smelting raw materials, it is difficult to control the composition of anode copper within the standard. The quality of cathode copper during the refining process has always been a hot and difficult point in copper smelting research. This article research and explore the effect of magnetic field synergy on the copper electrolysis process by adding a magnetic field and a transition cell to the original circulation pipeline of copper electrolysis, and compared the distribution of Cu²⁺ in the electrolytic cell, the clarity of the electrolyte, the composition of the anode slime, and the quality and output of the cathode copper before and after applying a magnetic field. The results show that the magnetic field can strengthen the diffusion performance of Cu²⁺ and accelerate the anode dissolution rate. Under the action of the magnetic field, the copper precipitation at the cathode increases by 10%, the current efficiency increases by 3%, and the residual pole rate decreases by 9%. The magnetic field can promote the self-purification of the copper electrolyte, reduce the concentration of arsenic, antimony and bismuth impurity ions in the electrolyte. After applying a magnetic field, the antimony element content in the anode slime increases by 56.2%, the bismuth content increases by 24.5%, and the arsenic content increases by 5%. The synergistic effect of the magnetic field can promote the sedimentation of anode slime, reduce the number of cathode copper anode slime particles, and reduce the probability of cathode copper particle formation by 21% after applying a magnetic field.

Abstract:The removal of As, Sb, and Bi impurities has always been a hot issue in copper electrolytic refining. At present, the most widely method is the electrowinning. This process has disadvantages such as low removal efficiency, low current efficiency, arsenic poisonous gas generated on the cathode, and the impurities cannot be completely removed, some black copper powder produced during the electrification process. In response to this problem, Yanggu Xiangguang Copper Industry Co., Ltd. has developed an antimony-based adsorbent, which can adsorb As, Sb, and Bi in the copper electrolyte, and can be reused. It is a green and environmentally friendly adsorption purification method. In this paper, the optimal process conditions have been experimentally studied, and the results show that Under these conditions of adsorbent As/Sb=1, the temperature 70℃, the stirring speed 350r/min, the adsorption rate of As and Bi reaches more than 80%; the best conditions for desorption are pH=10 and temperature 60℃, under these conditions, the desorption rate is over 85%; the adsorbent can be recycled for about 40 times, and the adsorption effect is good.

Abstract:Copper anode slime is an important raw material for extracting rare and precious metals, and the separation of impurities arsenic, antimony and bismuth has always been a research hotspot. In this paper, different combined leaching systems of hydrochloric acid, sulfuric acid and sodium chloride were used to carry out leaching tests on copper anode slime. The results showed that Au, Ag, Se, Pb, As, Sb and Bi could not be separated effectively when single hydrochloric acid, sulfuric acid and sodium chloride were used As leaching agents. When the leach agent is a combination of hydrochloric acid, sulfuric acid and sodium chloride, the directional removal of arsenic-antimony bismuth is better when hydrochloric-sulfuric acid is the leach agent, but the acid content is too high, which will easily cause equipment corrosion and increase the cost of subsequent treatment. When the leaching agent is hydrochloric acid, sulfuric acid and sodium chloride, As, Sb and Bi enter the acid leaching solution, and Au, Ag, Pb and Se enter the acid leaching residue, realizing the goal of directional removal of arsenic, antimony and bismuth from copper anode slime, and reducing the acidity of the leaching solution. By XRD and SEM-EDS, the changes of the solid phase before and after the copper anode slime leaching with hydrochloric acid, sulfuric acid and sodium chloride were analyzed. The results showed that Ag and Se existed in the form of Ag₂Se and AgCl before and after the leaching, and part of Se was converted into selenate. Pb mainly exists in the form of PbSO₄.

Abstract:The pyrometallurgical copper smelting process is restricted due to environmental protection issues, and the development of the direct oxygen pressure leaching process has become the focus of attention. The influencing factors of the oxygen utilization rate in the oxygen pressure leaching process was analyzed. The gas-liquid two-phase flow was numerically simulated by the technology of computational fluid dynamics. The effects of the shape of the stirring blade, the rotation speed, and the liquid-solid ratio during the leaching process on the oxygen concentration distribution in the autoclave were clarified. Three sets of copper sulfide concentrate oxygen pressure leaching industrial tests were carried out in a 30L four-compartment horizontal autoclave by changing the feeding speed, liquid-solid ratio and exhaust time and other parameters. The results show that the oxygen utilization rate can reach 94.1% when the liquid-to-solid ratio is 8∶1, the rotation speed is 300r/min, and the blade type is double-layer propulsion.

Abstract:Copper matte bottom blowing technology has become a current development trendin copper smelting industry. The smelting process is divided into fully hot material, cold and hot mixture materialand fully cold material. The heat balance in the furnace is different for different raw materials, and the oxygen concentration ofthe gas entering the furnace is different.Qinghai Copper Industry Co., Ltd. is the first domestic smelting company that adopts continuous blowing process treating the full-cooled raw material for copper production. This article analyzes the influence of oxygen concentration on the bottom blowing of copper smelting based on the companys production practice.The results show that increasing the effective flux of a single oxygen lance, reducing the number of oxygen lances, and controlling the oxygen concentration of 36% to 38% are important measures to prolong the life of the oxygen lance and shorten the time for shutting down and replacing the oxygen lance;a reasonable oxygen concentration should be used to control the appropriate three-phase thickness to ensure that all production indicators of the converting furnace. It is recommended that the oxygen-enriched concentration corresponding to cold copper matte blowing, hot copper matte blowing, and cold and hot copper matte mixed blowing is 36%~38%, 28%~32%, 31%~34%.

Abstract:The large-scale, intensive, and intelligent development of the non-ferrous metal smelting industry has promoted the development of the fluidized roaster technology to large-scale, high-efficiency, and intelligent development. This article introduces the technological characteristics and structural parameters of a large-scale fluidized roasting furnace. In view of the deformation, smoke and air leakage problems of the early 109m² fluidized roasting furnace, the 152m² fluidized roasting furnace developed in the later stage has been optimized in terms of process parameters and furnace body structure, and adopts integral casting technology. Practice has proved that the 152m² fluidized roasting furnace has stable running conditions, simple operation and advanced technical indicators. The future fluidized roasting furnace will further develop in the direction of high efficiency, low pollution and intelligence.

Abstract:A large zinc polar plate is conducive to save investment, expand production capacity, and improve production efficiency. However, the production control requirements are also high. Improper control of key points in the production process will affect the zinc plate quality and increase the cost of electrowinning. In this paper, combined with the production practice of 3.2m² large polar plate of Yunxi Wenshan Zinc Indium Smelting Co., Ltd., the influence factors of zinc electrowinning quality and cost are analyzed, which including new solution quality, cathode and anode plates, electrolytic liquid circulation, bath temperature, acid zinc ratio, precipitation cycle, cell management. After optimizing, analyzing and improving the above factors, zinc plates with high chemical quality and better density are obtained, and economic and technical indicators such as electricity efficiency and DC power consumption are excellent, which shows that the improvement measures can stabilize the production and is of positive significance in reducing costs and increasing efficiency.

Abstract:The method of preparing crude cobalt hydroxide by using active magnesium oxide slurry to precipitate cobalt ions in the cobalt raffinate has the problem of unstable cobalt product quality when using the low-cobalt solution as raw material. In response to this problem, this paper investigated the effects of magnesium oxide mass concentration, reaction temperature, end pH, cobalt and copper ion concentration, washing liquid-solid ratio on the cobalt content and magnesium content in the cobalt hydroxide. The results show that it has little effect on the quality of crude cobalt hydroxide when the mass concentration of active magnesium oxide is 2%~10%. It will improve the efficiency of preparation of crude cobalt when the temperature and end pH reach 45℃ and 7.3, respectively. In addition, the higher concentration of cobalt ions and the lower concentration of copper ions are in the solution, the more cobalt grade is in the crude cobalt hydroxide. Industrial production shows that crude cobalt hydroxide which contains higher magnesium can reach the industry second-class product standards after being washed with water.

Abstract:Refractory metals are more and more widely used in high-precision fields, but their reserves are low and mostly exist in polymetallic associated minerals, making it difficult to extract. At present, most of the processes for preparing metals and alloys by molten salt electrolysis are based on metal oxides or chlorides as raw materials. Oxide has low solubility in molten salt and poor reduction kinetics; although chloride has good solubility, its preparation process is complicated, corrosive, and pollute the environment. Based on the analysis of the electrochemical behavior of vanadate, chromate and titanate, this paper proposes a new process for preparing metals by using refractory metal oxoates as raw materials in molten salt electrolysis. This process has the advantages of short process flow, no harmful gas generation, high current efficiency, avoiding subsequent impurity removal, etc., and conforms to the principle of efficient metal preparation in a short process.

Abstract:A low grade super large refractory gold deposit belongs to Carlin type gold deposit. The gold grade is low and the ore is difficult to separate. The comprehensive benefit is not ideal by using conventional beneficiation process and pre-oxidation technology. A research institute carried out process mineralogy research on the raw material and exploratory tests such as flotation, direct cyanide leaching, roasting-cyanide leaching, and biological pre-oxidation-cyanide leaching in the laboratory. The test results show that the separation of sulfur and arsenic in the mine cannot be realized by using arsenic-suppressing and sulfur-floating technology. The reason is that the particle size of arsenopyrite is too fine, and arsenopyrite and pyrite are associated and symbiotic. When pyrite is floated, the association of arsenopyrite and pyrite is floated into the concentrate. On the research basis, the research institute proposed a combined beneficiation-metallurgy process scheme ‘preoxidation-ore desliming-sulfur arsenic coflotation-sulphurization-arsenic flotation-boiling roasting-cyanidation leaching’. The key technologies that the scheme can implement are sulfur-sulphurization-arsenic flotation technology and raw ore desliming technology. At present, the experiment of sulfur suppression and arsenic flotation has been successfully reported. The methods of ore desliming include cyclone desliming and flotation desliming. In the future, the implementation of this combined beneficiation and smelting process will greatly reduce the comprehensive beneficiation and smelting cost of such refractory gold ores.

Abstract:Waste printed circuit boards contain a variety of hazardous substances and recyclable valuable metals, and their clean and efficient resource disposal is currently a hot spot for domestic and foreign research scholars. Compared with the hydrometallurgy process, the pyrometallurgy process has more advantages in the treatment of waste printed circuit boards, but different furnaces are also different in terms of investment, environmental protection, energy consumption, and metal yield. At present, the commonly used furnace types for processing waste printed circuit boards include blast furnace, Kaldor furnace, side blow furnace, top blow furnace, etc. The top-blowing furnace for processing waste printed circuit boards has the advantages of strong raw material adaptability, flexible process, high precious metal recovery rate, little environmental pollution, and low energy consumption. Moreover, there are mature industrialization practice cases in China, and the process should be promoted.

Abstract:Yanggu Xiangguang Copper Industry Co., Ltd. uses vulcanization precipitating arsenic-gypsum neutralization process to treat acid sewage water from flue gas sulphuric acid production.During the treatment process, gases such as hydrogen sulfide and carbon dioxide are generated, which need to be absorbed by the treatment system to ensure zero emission of fugitive gases.The hydrogen sulfide in the first stage of the detoxification tower in the vulcanization precipitating arsenic process cannot be completely absorbed. It can be completely absorbed by connecting the outlet pipe of the first stage of the detoxification tower to the fan inlet of the second stage of the detoxification tower, and the absorption liquid can be recycled as the hydrogen sulfide reaction liquid.The unorganized gas generated in the gypsum neutralization process includes hydrogen sulfide and carbon dioxide. After two lye spray washing system transformations, the unorganized gas in the gypsum production can be effectively controlled. The reaction tank is improved by improving the gas extraction and negative pressure effects of the reaction tank.Measures such as the location of the liquid inlet pipe and the addition of a self-circulating diaphragm pump at the bottom of the reaction tank slowed down the reaction siltation tank and blockage, so that the gypsum fan’s air extraction pipeline was unblocked and the air extraction effect was ensured.

Abstract:Based on the current national requirements for air pollutant emission limits of non-ferrous metal industries and industry policy specifications, this paper compares and analyzes the advantages and disadvantages of the current flue gas desulfurization technologies, and the two flue gas treatment schemes of a copper smelter were comprehensively compared. The results show that various flue gas desulfurization technologies have advantages and disadvantages, and it is difficult to find a perfect desulfurization technology. The selection of flue gas desulfurization process technology requires comprehensive consideration of equipment investment costs, facility footprint, desulfurization agent costs and supply stability, by-product disposal and benefits, etc., calculate technical costs and operating costs, and select the most cost-effective desulfurization process.

Abstract:Non-ferrous metal hydrometallurgical wastewater contains a large amount of organic matter, sulfate, sodium chloride and other salts. Frozen denitrification technology uses the principle of solid-liquid equilibrium to achieve freezing separation, which can precipitate low-solubility solutes under low temperature conditions to obtain high-purity salt crystallization and concentrated wastewater, but the remaining concentrated wastewater still contains high concentrations of Na₂SO₄ NaCl and COD. Still can’t discharge outside. In this paper, freezing denitrification-evaporation concentration technology is used to treat COD high-salt wastewater containing Na₂SO₄ and NaCl, and the effects of freezing denitrification temperature and initial concentration of NaCl on the product are analyzed. Concluded as follow: In the freezing temperature range of 0~10℃, the residual COD in frozen crystal is less than 30%, and the best freezing temperature is 8℃; The higher the ratio of Na₂SO₄ NaCl mass content, the higher the purity of the precipitated Na₂SO₄ crystals; Taking advantage of the difference in the concentration ratio and solubility of the substances in the sodium chloride-sodium sulfate-water three-phase system, the separation of sodium sulfate and sodium chloride is effectively realized. The experimental products are Glauber’s salt, Na₂SO₄ crystals and hetero salt products. Using this technology to treat Na₂SO₄ and crude salt industrial products can realize the resource utilization of COD-containing high-salt wastewater, and realize zero pollution discharge.

Abstract:In view of the fact that the rhenium leaching rate of the ammonium rhenate recovery system is not high and the product ammonium rhenate grade is low, a copper industry company adopts a small-scale laboratory research method to conduct an experimental study on the improvement of the leaching process of the rich rhenium slag，in which, the original high acid oxidation leaching was changed to a single hydrogen peroxide system oxidation leaching. The results show that the concentration of rhenium in the leaching solution can reach 1988mg/L under the conditions of 400mL/100g slag, reaction time 120min and leaching temperature of 70℃. Compared with the original production process, the leaching rate of rhenium is greatly improved, reaching an average of over 90%. At the same time, the impurity concentrations of bismuth and arsenic decreased from 110~150mg/L and 260~400mg/L to 33.62mg/L and 14.35mg/L, respectively, and the leaching of impurities was significantly reduced.

Abstract:The waste acid emitted from copper smelting flue gas treatment has the characteristics of large emissions, high arsenic content, and complex composition. At present, calcium carbide slag is widely used as an arsenic removal agent, and the arsenic removal rate can reach about 60%, but there are problems such as large consumption of calcium carbide slag and high cost of waste acid treatment. In order to reduce the cost of waste acid treatment and reduce inventory pressure of self-produced copper slag, a copper smelter plans to use self-produced copper slag instead of purchased calcium carbide slag to remove arsenic from waste acid, and conduct exploratory experiments. The results showed that the arsenic removal rate was only 18.03% under the conditions of pH=2.19, reaction temperature 40℃, and stirring for 30 minutes, indicating that the direct arsenic removal effect of copper slag was not good; under optimized conditions, when the dosage of copper slag is 80kg/m³, the amount of hydrogen peroxide is 50L/m³, the reaction time is 6h, and the initial pH of the solution is 11, the copper slag achieves the best arsenic removal effect and the arsenic removal rate up to 99.5%. The smelter will continue to explore the process of synergistic removal of arsenic from calcium carbide slag and copper slag according to a certain ratio, and explore a technical route for arsenic removal with both technical and economic advantages.

Abstract:Silver separated slag is the remaining tailings of copper anode slime extracted major precious metals. Daye Non-ferrous Metals Co., Ltd. produces about 2000 tons of silver separated slag each year. In order to recover valuable metals, the company designed a segmented comprehensive recovery process. After the smelting, water crushing and leaching processes of silver separated slag were completed, the average direct yields of lead, bismuth, antimony, tin, gold, silver, platinum, palladium and tellurium were 93.65%, 95.42%, 95.28%, 90.66%, 99.07%, 98.39%, 96.15%, 90.13% and 95.65%. The average grade of crude calcium stannate was 12.03%, and the average direct yield of tin in the tin precipitation test was 97.01%.The refining test of tin showed that the average tin content in acid-washed calcium stannate was 15.97%, and the average direct yield in silver separated residue was 81.57%. The average antimony content of crude sodium antimony is 44.56%, and the average direct yield of antimony in the antimony precipitation test is 94.97%.The refining test of crude sodium antimony showed that the grade of sodium antimony was 51.3%, and the average direct yield of antimony in the silver separation slag was 82.63%. The direct yields of gold, silver, lead, bismuth, platinum and palladium in precious lead are 98.01%, 97.57%, 86%, 83.44%, 80% and 79.98%, respectively. The direct yield of tellurium in slag is 85.03%. Under this process condition, the whole production process was carried out in alkaline and reductive environment, and there was no harmful gas overflow in the smelting process. The benefit of CNY 40739.5 can be achieved by processing 1ton of silver separated slag.