China Nonferrous Metallurgy

Abstract:The stockpile quantity of the low grade refractory oxygen-sulfur mixed lead-zinc ore in Lanping mine is 38 million tons, with the grade of Zn5.73 % and Pb1.32 %. The ore is extremely complex, with low grade, high oxidation rate, large mud content and fine disseminated grain size. It is a typical refractory ore, and its utilization technology is a world-class problem. Yunnan Jinding Zinc Industry Co., Ltd. invested a large amount of experimental research funds for research on beneficiation technology, but did not achieve good results. In order to deal with the low-grade refractory oxygen-sulfur mixed ore economically and effectively, the company decided to adopt a combined process of hydrometallurgy first and then beneficiation. First, the new technology of “leaching-extraction-electrolysis” is used to treat the zinc oxide in the oxygen-sulfur mixed ore, and then the flotation process is used to treat the zinc sulfide in the leaching residue. Under the optimal leaching process conditions determined in the experiment, the recovery rate of zinc oxide is 92%, the recovery rate of zinc sulfide is 95%, and the total recovery rate of zinc resources is greater than 90%, which is 30% higher than the traditional process of beneficiation first and then metallurgy. The combined process of hydrometallurgy and beneficiation has advantages such as strong adaptability to raw materials, short process, high recovery rate, and it is a closed loop, does not produce waste water or exhaust gas, and the generated tailings are general solid wastes. Its environmental protection and economic benefits are obvious, and it is practical.

Abstract:Domestic plants producing alumina by Bayer process, the decomposition process mostly adopts large flat bottom mechanical stirring decomposition tank. The wall of the decomposition tank is easy to scab, and the scab grows fast. The traditional cleaning method will cause the organic matter in the scar to re-enter the system, which can not reduce the harm to the production. The results show that the main component of the scab is Al(OH)₃, followed by sodium carbonate, sodium oxalate and other organic carbon (TOC), therefore, the method of washing causticization was determined to remove the organic matter in the scab. The results of laboratory test and industrial test showed that the removal rates of Na₂C₂O₄、Na₂CO₃and TOC were 97.32%, 93.99% and 73.45% respectively when excessive lime milk was added, and the total carbon content in the scab of decomposition tank after washing was 0.013%. After ten months of industrial application, the contents of organic carbon and oxalate in the system decreased significantly.

Abstract:Most of the domestic polysilicon production lines are designed and built according to the solar level polysilicon standard which does not meet the requirement for electronic grade polysilicon production. This paper analyzes the electronic grade polysilicon national standard. The main standards of electronic grade polysilicon are the concentration of impurity, minority carrier lifetime, the concentration of carbon, the concentration of oxygen, the base metal impurity, the surface metal impurity and the external quality requirement. The problems in the electronic grade polysilicon production processes are identified based on the the analysis of the influence of the above parameters, which would give guidance to the production process improvement and technology research study of the manufacture of the electronic grade polysilicon.

Abstract:Chlorosilane in polysilicon production process belongs to hazardous chemicals. In order to ensure that there is no leakage in the material transportation process, shield pump is generally selected. This paper introduces the structure of the shield pump, briefly describes the use of the shield pump in the polysilicon industry, analyzes the common faults of the shield pump, makes statistics and Analysis on the forms and causes of the faults, points out the relationship between the faults of the shield pump and the materials and production operation, and finally puts forward some improvement measures in the aspects of equipment layout, design and selection, production and use, so as to ensure that Safe and stable operation of canned motor pump.

Abstract:Aiming at the characteristics of electrocatalytic oxidation technology in the treatment of salty wastewater with strong oxidation ability, simple equipment, and no secondary pollution, this article uses electrocatalytic anodes of different materials to compare and analyze the treatment of high-salt wastewater containing organic matter produced by hydrometallurgy. The results show that the order of the anode oxygen evolution overpotential of different materials is Ti/Ta₂O₅-IrO₂ electrode＞graphite electrode＞Ti/RuO₂-IrO₂ electrode; The COD removal efficiencies of the three electrodes for treating high-salt wastewater are 62.0%, 43.7%, and 49.6%, and the COD removal energy consumption are 16.7, 61.7 and 41.5W·h/mg. Although the treated wastewater still contains a certain concentration of COD, the negative impact on the subsequent evaporative crystallization of sodium sulfate is significantly reduced.

Abstract:The application of converters in the treatment of copper dross is an emerging technology application, and its energy consumption indicators, product quality indicators and operating labor intensity havegreatly improved. However, the high-temperature flue gas and fume dust produced by the process make the lifetime of the flue gas outlet 1~2 months and the lifetime of the water-cooled hood 3~5 months, which severely restricts the operating rate of the furnace.To solve this problem, a lead smelter has achieved good water flow, water temperature and flue gas outlet temperature indicators by improving the copper water jacket cooling device at the flue, optimizing the design of water-cooled flue gas cover and improving the cooling water supply system. The improved copper slag converter runs smoothly, and achieves excellent results in the production practice of flue gas cooling capacity, corrosion resistance and maintenance simplicity.

Abstract:The bismuth content in the dust of a smelter reaches 2% to 4%, which is not suitable for the use of atomic absorption spectroscopy, hydride generation-atomic fluorescence method and thiourea photometry. However, when the EDTA titration method is used, there are problems such as long time-consuming, narrow titration acidity range (pH 1.5 to 1.7), and difficulty in controlling acidity in the titration process. In this paper, inductively coupled plasma atomic emission spectroscopy (ICP-OES) was used to test the determination of bismuth in copper smelting dust. The sample decomposition method, instrument working conditions, spectral line selection, and matrix effect were analyzed, and the following results were obtained. Adopting a longer cleaning time of the atomization system can overcome the blockage of the atomizer and eliminate the interference; in a 5% nitric acid medium, the antimony content of less than 3% in the sample will not undergo hydrolysis reaction and will not interfere with the determination; use Bi 190.241nm as the analysis line to avoid overlapping with the Cu 223.00nm spectrum line, which can eliminate the interference of copper on bismuth during the measurement process. The recovery rate of bismuth content in the smoke and dust determined by this method is 99.0%~101.1%, the relative standard deviation is 1.51%, and the result is accurate and reliable.

Abstract:The nickel electrolysis process needs to remove iron. When the sulfuric acid system is used for nickel electrolysis, the yellow sodium iron vitriol method is generally used to remove iron. There are some problems such as a large amount of alkali consumption, the produced iron slag containing high nickel, and the nickel and iron that enter the iron slag difficult recovery. In the treatment of materials containing nickel with nitric acid, a kind of iron slag containing sulfur is produced. In order to recover iron resources from iron slag, this paper analyzes the properties of iron slag. The method of ammonia leaching is proposed for desulfurization, and the ammonia dosage, reaction time and reaction temperature on desulfurization effect are studied. The results show that when the amount of ammonia is 3.0 times, the reaction time is 1h, and the reaction temperature is 85℃, the iron concentrate containing more than 58% iron and less than 0.3% sulfur can be produced. The leaching agent can be recycled in the leaching process, which is a new clean desulphurization technology.

Abstract:The precipitated gold solution from the copper anode slime treatment process in the smelter of Daye Nonferrous Metals Co. Ltd. contains a small part of Au and most of Pt and Pd. In order to improve the recovery rate of precious metals, the company chose to recover precious metals directly from the precipitated gold solution and carried out a large number of experiments. The adsorption of F-resin on Au, Pt, Pd noble metal ions in gold precipitation solution was studied by two-stage exchange column equipment, and the following conclusions were reached. The adsorption effect of F-resin on Pt ion is general, and the adsorption effect on Au ion and Pd ion is better; in the range of 0~300h, the adsorption of Au and Pd ions in the primary resin exchange column is better; in the range of 120~300h, the adsorption of Pt ions in the secondary exchange column is better; between 120 and 430h, the ion concentration of Au and Pd in the solution after adsorption by secondary exchange column resin is very low; temperature and flow rate have little effect on the adsorption of Pd by F resin; reducing the flow rate and increasing the adsorption temperature of the raw solution can improve the adsorption effect of F-resin on Pt ions.

Abstract:The ammonia alkali environment in the production process of using alkalinity reaction precursor is helpful to avoid the influence of formaldehyde and human measurement error on the reaction process. Through theoretical analysis and statistical analysis of the numerical relationship between the two, a target planning model based on calculation and actual measurement deviation is established and solved by MATALB. Finally, the change characteristics of precursor particle size and surface morphology in the actual production process are verified. The results show that the theoretical value of ammonium concentration is 8/7 times of alkalinity, and the proportional coefficient is linear The combined value and the average value are slightly larger than the theoretical value; with the increase of the designed ammonium concentration, the corresponding coefficient shows a downward trend, the greater the deviation between the calculated value and the measured value is; the deviation between the calculated value and the measured value is less than ±0.3, which can meet the production requirements, but the particle size fluctuation of alkalinity control is small, and the sphericity of the precursor is higher.