China Nonferrous Metallurgy

Abstract:Anode passivation and floating anode slime are the main factors that affect the production of copper electrolytic refining, which will cause Weakening productivity, Increased power consumption, and the decrease in the quality of cathode copper. The main reason is that anode copper and electrolyte contain impurities. The formation mechanism of anodic passivation in the present literature includes: arsenic content can promote or inhibit anodic passivation; CuSO4 salt film formed on the surface of anode copper causes passivation; copper oxide and zinc powder together cause passivation; impurities Bi, Ni, Pb, Ag, Se, Te and O accelerate anodic passivation. As, Sb and Bi are the impurity elements with high content in floating anode mud, while Cu, Pb and Ag are the impurity elements with high content in normal anode slime. In this paper, the research results in this field are analyzed and summarized. The formation mechanism and control technology of anode passivation and floating anode slime in copper electrolysis are comprehensively introduced. The technical points of stabilizing copper electrolysis production and improving the quality of cathode copper are put forward.

Abstract:The converter slag produced by Chuxiong Dianzhong Nonferrous Metals Co., Ltd. has a continuously high copper content, which has impacts on the subsequent production operation and process index control of copper slag flotation. In response to this problem, the company studied the chemical composition and phase of the converter slag, the loss form of copper metal in the converter slag, and the copper content data of the converter slag. The copper matte grade, the amount of cold material added, the timing of addition, and the size of the particle size, the amount of quartz flux added, slagging and slag discharge operations were also analyzed in depth, and control measures to reduce the copper content in the slag were put forward. The main measures were such as controlling the oxygen-enriched concentration of converter blowing at 23%-25%, controlling the particle size of the cold material entering the furnace under 300mm, and strictly implementing the cold material adding system, controlling the silicon dioxide content of converter slag at 19%-24%; standardizing slagging end point determination and slag discharge operation, etc. By adopting the above rectification measures, the copper content of the converter slag was reduced from 6% to 3%, which can be continuously and stably controlled, and the metal copper recovery rate has been increased.

Abstract:Before the technological transformation，Jinlong Copper Co., Ltd. used the cyclone electrowinning system to treat the copper anode slime leaching solution. Due to the limited design capacity of the cyclone electrowinning system, only a small amount of the secondary leaching solution with low impurity content was processed, and most of the leaching solution was sold. The annual loss is 10.86 million yuan. The company decided to carry out the transformation, there are two treatment options. One is to continue the existing cyclone electrowinning process and expand the production capacity; the other is to deal by the electrolytic purification process. After benefit comparison, it is found that it is more economical to use electrolytic purification process. After the company determined the treatment plan, the two methods of independent system treatment of leachate and mixed leachate and waste electrolyte were compared, and found that the mixed treatment method of leachate and waste electrolyte is better, and the product composition is relatively stable and can meet the production of standard copper. Production practice shows that the application of this program reduces costs and investment, and improves processing capacity. It also increases metal recovery rate and reduces environmental hazards. It provides a reference solution for the copper smelting industry to process similar leaching solution.

Abstract:Yunxi Wenshan Zinc Indium Smelting Co., Ltd. use antimony salt purification method to purify the supernatant in zinc hydrometallurgy. In this process, the unit consumption of zinc powder is the most important economic and technical index, and for every additional 1t of zinc powder consumption, the increased cost is about 6000 yuan. At present, the domestic zinc powder unit consumption is generally 50~60kg/t. The company adopted measures to control the quality and supply of the supernatant, the pH value of the solution, the reaction temperature, the reaction time, the amount of antimony salt, the particle size of the zinc powder, and the refined operation to reduce the zinc powder unit consumption from about 60kg/t to about 48kg/t, saving more than 7 million yuan in production costs. In addition, the primary qualification rate of the new liquid and the quality of the new liquid have been significantly improved, and the economic benefits are significant. Its experience can provide a certain reference for hydro zinc smelting enterprises.

Abstract:In the early stage of production, a company used α-nitroso-β-naphthol process to recover cobalt from the purifying cobalt slag from wet zinc smelting. There were problems such as large consumption of chemical agents, low cobalt content in cobalt enrichment slag, and benefit deficit. The company later adopted ammonium persulfate oxidation precipitation method to enrich cobalt, forming a practical method for recovering cobalt from purification slag with high cobalt enrichment ratio, low cost, short process, easy operation and environmental protection. The method is divided into three stages. The acid leaching stage includes dilute acid selective leaching and countercurrent acid leaching. Under the better process parameters, the leaching rate of cobalt reaches 95.8%; the Fe content of the filtrate is less than 80mg/L under the better process parameters in the oxidation iron removal stage; the cobalt oxide precipitation stage can obtain cobalt-rich slag containing 20% cobalt and 18%-20% zinc. While the cobalt-precipitating slag is washed with acid water, a cobalt-rich slag containing less than 10% zinc and more than 30% cobalt can be obtained, which can be sold as cobalt concentrate. The process equipment is simple, the process is short, and the cost is controllable. It can provide a reference for the comprehensive recovery of valuable metals in purification slag from zinc hydrometallurgy.

Abstract:Daye Nonferrous Metals Smelter adopts oxygen-enriched top-blowing smelting technology on Ausmelt furnace, and the overall process control is very mature. Increasing the operating rate of the Austrian furnace is the only way to increase production capacity. The smelter analyzed the shutdown failures in 2018 and found that boiler failure, spray gun failure and replacement, coking and stacking, air and coal supply system failures, and cleaning the spray gun weight are the key factors affecting the internal shutdown of the Austrian furnace, and the ratio reached 82.67%. Measures such as strict control of boiler water quality and strengthening of daily maintenance have reduced the failure rate of boilers; improving spray gun structure to increase spray gun life; measures such as regular cleaning of flue working door coke blocks, using coking inhibitors, and improving coking operation techniques to reduce the flue coke; measures such as switching to nitrogen for instrument air and improving steam drum drainage valves to reduce fan failures; strengthening maintenance to reduce the failure rate of the pulverized coal system; refining operation to reduce the frequency of cleaning spray guns. After the above measures are taken, Daye Nonferrous Ausmelt furnace's annual system operating rate in 2019 reached 95.5%, which is an increase of 1.8% from 93.7% in 2018, and the annual output of copper reached 326000 tons. The effect is remarkable.

Abstract:The complex high-indium material from a lead smelter is an intermediate product of smelting, and the leaching rate is lowbyusingconventional acid leaching process.In response to this problem, this paper used three processes, such as hydrochloric acid-sulfuric acid mixed leaching, pressurized acid leaching, sulfating roasting-low acid leaching, to test this complex high-indium material. Under the optimal process conditions of each test,the results are as follows. Using the hydrochloric acid-sulfuric acid mixed acid leaching process, the leaching rate of indium can reach 75.87%, and the indium content of the leaching residue can be reduced to 0.32%; using the pressure acid leaching process, the leaching rate of indium can reach 82.54%, and the indium content of the leaching residue can be reduced to 0.21%;using sulfuric acid roasting-low acid leaching process, the leaching rate of indium can reach 93.28%, and the indium content of the leaching residue can be reduced to 0.09%.Though comparison of these three indium leaching processes, the “sulfating roasting-low acid leaching” process is more suitable for extracting indium from this complex indium-containing material.

Abstract:Tellurium anode slime was produced in the tellurium electrowinning refining process, whose tellurium content accounts for 3% to 20% of the total tellurium content, which leads to a decrease in the direct yield of tellurium. The main component of tellurium anode slime is high sodium tellurite, which is insoluble loose granular or flaky crystals generated by the Oxygen at anode reacting with sodium tellurite, most of which settle to the bottom of the tank, and a small amount adhere to the cathode plate surface. The high valence tellurium salt will contain low valence tellurium salt in the process of crystal growth, sedimentation and adhesion, which will increase the loss of tellurium. The tellurium content in the anode slime can be controlled below 3%, the optimal index can reach 1.5%, by changing the anode structure, setting polyester bags on the anode, adding an appropriate amount of reducing agent in the electrolyte, increasing the oxygen removal facilities and stirring and washing the anode slime with hot alkaline solution. The main treatment methods of tellurium anode slime include acid leaching self-reduction method, mixed acid solution replacement method and sulfide reduction method, which method has its’ advantages and disadvantages, and can be selected according to the actual process.

Abstract:Lead anode slime is a high value-added material produced in the production process of electric lead, and comprehensive recovery of valuable metals in the lead anode slime is a growth point of the economic benefits for smelting enterprises. A smelter used traditional pyrotechnical process to treat lead anode slime, which had problems such as low crude silver production capacity, poor comprehensive recovery capacity, and unsatisfactory environmental protection. Later, the company invested in a crude silver production line and built a supporting antimony production line, and carried out technical transformation for the original bismuth production line. After the overall technological upgrading and transformation, the processing capacity of lead anode slime reaches 20000t/a, and the comprehensive recovery rate of valuable metals such as silver, gold, lead, bismuth, copper, and antimony is above 99.5%. The direct yields of the main metals silver, antimony, and bismuth reached 94%, 90%, and 85% respectively, reaching the industry-leading level. The processing cost of recycled metal has been drastically reduced, and the annual benefit has increased by more than 20 million yuan. This article introduces the upgraded process and gives a detailed description for the production operation.

Abstract:The cooling circulating water system in the polysilicon production process is mainly used to cool the material, and is generally divided into an open circulating water system and a closed circulating water system. The main process components of the open circulating water system are open, and the source of supplementary water is generally industrial softened water. During the operation of circulating water, CO₂ content reduction, alkalinity increase, pH value increase, and turbidity increase will occur. It is necessary to monitor and control the indicators of cooling water and select suitable water treatment chemicals for dosing. The closed circulating water system is a closed system, and the requirements for circulating water are stricter. Compared with the open circulating water system, the components are more complicated, but the water quality control is easier. At present, the newer water quality control technologies include phosphorus-free descaling agent, electronic descaler and new anti-scale and anti-corrosion alloy materials. These new technologies can reduce subsequent cost input, and can reduce or even eliminate the cleaning of cooling towers and equipment. In new plant construction and technological transformation projects, the new technologies should be selected as far as possible.

Abstract:A smelting company used a rotary kiln process to recover zinc oxide from the iron slag in hydrometallurgical zinc process, and originally used the traditional calcium desulfurization process to treat the flue gas from rotary kiln, which had the problems such as poor desulfurization effect, substandard exhaust gas, difficult disposal of gypsum slag, and low operating rate. After many verifications, the company decided to switch to zinc oxide-acid desulfurization process. The desulfurization agent adopts self-produced zinc oxide fume or calcine. The sulfur dioxide produced is returned to the acid production system, and the acid hydrolysis liquid is returned to the zinc system. The system does not produce secondary solid waste. After the new system was put into production, the operation was stable, which increased the economic benefits of the enterprise, and the exhaust emission index was better than the national standard. This article introduces the technological process, technological parameters and equipment of the modified technology in detail, and summarizes and explains the problems that should be paid attention to in production practice.

Abstract:Yanggu Xiangguang Copper Industry Co., Ltd. uses the floatation smelting process to smelt copper concentrate. As the arsenic content of the copper concentrate entering the furnace increases, the arsenic content in the electrostatic precipitator dust also increases, and the arsenic continues to circulate in the system, excessive arsenic content in the anode plate will affect the quality of the cathode copper. The company conducted an arsenic extraction test using samples stored during the preliminary test. The extraction process includes two processes: water leaching and acid leaching. The water leaching test showed that if the copper fume was leached, 67.5% of the copper and 69.9% of the zinc in the soot were preferentially removed, and 97.94% of the arsenic was enriched in the water leaching residue. The acid leaching test showed that the leaching rate of arsenic can reach 92.26% under the condition of the mass ratio of liquid to solid is 5∶1, the concentration of sulfuric acid is 200g/L, the reaction temperature is 85℃, and the leaching time is 4h. After washing, the leaching rate of impurity elements such as Cu, Sb, Bi, Zn and Fe is relatively high. When arsenic is recovered, attention should be paid to impurity removal and prevention of heavy metal pollution.

Abstract:Yantai Guorun Copper Industry Co., Ltd. adopts the production process of oxygen-enriched side blowing smelting process and multi-gun top blowing continuous blowing process and fire anode refining continuous copper smelting production process. In response to the new environmental protection standards, the original flue gas treatment system is also need to be upgraded and transformated. According to the current situation that the exhaust treatment volume of the existing equipment is low, the anode furnace process adopts the lean oxygen combustion technology, the anode furnace oxidation period flue gas is split to the acid purification inlet, and the top blowing slag outlet flue gas is sent to the side-blowing furnace flue, and adopts other measures such as transformation of flue system, adjustment of negative pressure distribution, configuration of new equipment, and so on. The modified flue gas treatment system has the ability to process flue gas from continuous copper smelting. The exhaust dust content is less than 10mg/m³, the SO₂ concentration is less than 30mg/m3, and the NO_x concentration is less than 50mg/m³, reaching the fourth period emission standards in Shandong Province, and saving 982000 yuan per year for desulfurization materials. This article gives a detailed introduction to the upgrade and transformation of the flue gas treatment system, and explains some optimization and transformation details.

Abstract:The fire assay is a classic analysis method in analytical chemistry. For the silver loss during the smelting and ash blowing process, the standard analysis method uses the second test or the third test to make corrections. Although the calibration results are very good, there are problems such as long analysis process, high operation cost, and increase of human operation error. In this paper, through the classification experiment of copper concentrate, gold concentrate, blister copper, copper anode slime and other materials in copper smelting, a large number of experimental data are statistically analyzed, and the primary and secondary testing methods are used to calculate the silver correction coefficient of each material, and get the following results. When the silver content is less than 200g/t, the correction coefficient is 1.03; when the silver content is in the range of 200~500g/t, the correction coefficient is 1.025; when the silver content is in the range of 500~1000g/t, the correction coefficient is 1.02; when the silver content is greater than 1000g/t, the correction coefficient is 1.01. The control experiment and the significance test prove that the result of this method is accurate and reliable. Compared with the traditional fire assay method, this method solves the problems of time-consuming and errors caused by the second test or third test, and achieves the effects of energy saving, consumption reduction and time saving.

Abstract:In this paper, the uncertainty of the determination of copper content in anode copper by iodometry method is evaluated, and the sources of uncertainty in the determination process are analyzed, including sample quality, standard solution preparation, standard titration solution calibration and sample titration, etc. Through the establishment of a mathematical model, the uncertainty components are calculated, and then the uncertainty evaluation results are obtained according to the square root sum. The combined standard uncertainty is 0.20% and the expanded uncertainty is 0.40%. The experiment and results show that the difference between the copper content in anode copper determined by the iodometric method and the actual standard content is mainly derived from the calibration of the standard titrant and the sample titration, which can be controlled by the standardization of the standard titrant and the standardization of the sample titration to ensure the accuracy and reliability of the measurement results.

Abstract:The application of ion exchange resin adsorption technology in the recovery of nickel and cobalt in laterite nickel ore leaching solution is still in the research stage. The previous research results showed that the technology is feasible, and the corresponding process conditions were given.Based on the previous experimental research, this article conducted further experiments based on the previous conclusion that the initial pH value of the liquid phase is pH≥3, and the conditions and performance of resin regeneration, and reached a more mature conclusion.Experiments on the influence of pH value on the adsorbcapacity of the resin for each metal show that it is more appropriate to adjust the pH value of the adsorbed solution to 4 before implementing the adsorption process. The experiment of the influence of sodium hydroxide concentration on the regeneration performance of the resin shows that the resin regeneration can be achieved by first desorption with sulfuric acid and then transformation with sodium hydroxide solution. The sodium hydroxide concentration of the transformation solution used is 5%.The resin regeneration performance test experiment showed that the resin used in the experiment did not significantly decrease the adsorption capacity of the solution for nickel and cobalt after repeated regeneration.

Abstract:Scandia-stabilized zirconia (ScSZ) composite powders with different scandium content had been successfully prepared by co-precipitation method，using zirconium oxychloride and scandium oxide as raw materials, polyethyleneglycol (PEG800) as dispersant and ammonia as precipitant. The synthesized samples were characterized by means of TG/DSC、ICP、XRD、Raman and SEM. The influence of the doping scandium on the thermal stability of ZrO₂ precursor, the phase and morphology of ZrO₂ powder were systematically investigated. The influence of washing method on the morphology of ScSZ powder was also discussed. The ZrO₂ and ScSZ precursor were amorphous. The results demonstrated that the total weight loss of ScSZ precursor was greater than that of ZrO₂ precursor. And the diffraction peaks of the ScSZ powder were sharp after calcination, which were indexed to a mixture of the tetragonal and cubic ZrO₂ phases. The diffraction peaks of ZrO₂ powder was corresponding to the monoclinic ZrO₂ phase. The results showed that scandium doping promoted the transformation from monoclinic to tetragonal and cubic phases. Scandium doping has no obvious effect on the particle size of ZrO₂ powder, and the ZrO₂ and ScSZ powder displayed agglomerated morphology with particle size ranging from 0.5 to 3μm. Washing the powder with ethanol was conducive to reducing the primary particle size and agglomeration phenomenon of the ScSZ powder, and the agglomeration was relatively loose.

Abstract:The grade of copper-cobalt ore in Zambia is low, the occurrence of copper and cobalt is complex, and the leaching and recovery technology is immature. A smelter uses the “leaching-extraction-purification-cobalt precipitation” process to produce crude cobalt hydroxide from the copper-cobalt ore. In the leaching section, there is excess water in the production process, and before the purification section, the cobalt in the raffinate is difficult to concentrate, resulting in a waste of resources. This article uses acid leaching reduction-Lix984 extraction-HBL110 extraction process to test this copper-cobalt ore and has achieved satisfactory results. Using the reducing agent hydrogen peroxide and sodium sulfite combined method for acid leaching reduction, the leaching rates of cobalt and copper were 98.27% and 98.59% respectively. The copper is extracted and recovered with the extractant Lix984, and the three-stage countercurrent extraction copper extraction rate is 99.13%, and the cobalt extraction rate is 7.12%, achieving the purpose of separating copper and cobalt. The raffinate after copper extraction mainly contains Co and Fe, and the raffinate is pretreated with hydrogen peroxide, and then cobalt is extracted with the extractant HBL110. The extraction rate of cobalt reaches more than 99%, and the iron removal rate is also greatly improved.

Abstract:Residual laterite nickel ore is an important kind of laterite nickel ore, with a high content of Mg (10%~27%). In the laterite nickel ore high-pressure leaching project, it is usually used to neutralize the pressure leaching pulp, and the concentration of sulfuric acid in the pulp is usually 30~50g/L. However, the dosage of residual ore has a great impact on the leaching rate of nickel and cobalt. In order to make better use of residual laterite nickel ore, this paper carried out conventional leaching tests and reduction leaching tests. The test results show that as the dosage of residual ore increases (liquid-solid ratio decrease), the end-point acidity gradually decreases, and the leaching rate of nickel and cobalt gradually decreases; when the grinding fineness increases, the cobalt leaching rate increases significantly; the reaction proceeds rapidly, and the leaching time could be shortened in industry; when the dosage of leaching residual ore is the same in the conventional leaching and reduction leaching tests, the leaching rate of reduction leaching nickel is 5% to 25% higher than that of conventional leaching; when the dosage of residual ore is lower, the leaching rate of reduction leaching nickel is significantly improved; when the dosage of residual ore is less than 90g/L, the reduction leaching cobalt leaching rate is higher than that of the conventional leaching; when the dosage continues to increase, the reduction leaching cobalt leaching rate will be lower than that of the conventional leaching.