China Nonferrous Metallurgy

Abstract:The physical properties of the ternary material precursor are affected by various process parameters during the hydroxide precipitation reaction, including ammonia concentration, reaction temperature, pH value of the reaction process, reaction time, stirring rate, etc. Based on the traditional hydroxide co-precipitation process for preparing precursors for ternary cathode materials, this article innovatively used the seed template method, and conducted an analysis on the preferable process parameters of the co-precipitation reaction to reach the following conclusions: The optimal process parameters of the co-precipitation reaction obtained by one-step precipitation process include the reaction temperature of 50℃, the reaction time of 7h, the system pH value of 11.0, the stirring rate of 1100r/min, and the caustic concentration of 170g/L; The ternary material precursor prepared by the seed template process may has a tap density in excess of 2.1g/cm³, and a D50 range of 3~6μm, which, when compared with the other products currently sold on the market, is more uniform and more spherical in terms of particle size, and has smaller specific surface area, and is more suitable for use in the preparation of monocrystal ternary cathode materials.

Abstract:Systemic thermodynamic study and experimental basis study have been carried out on the thermal decomposition behavior of gypsum. The results show that in the solid-solid carbon thermal decomposition of gypsum, when the Ca:S ratio is 3, the conversion rate of gypsum to CaS reaches the maximum (81.33%), and the CaS content in the reaction product is 71.19%; In the gas-solid thermal decomposition of gypsum, when the CO/（CO+CO₂）concentration in the gas is 50%, the conversion rate of gypsum to CaS is 91.80%, and the CaS content in the reaction product is 93.51%. When the CaS is used as sulfurizing agent for matte smelting, the utilization rate of the sulfurizing agent can reach above 74%. Based on the results, the process of using gypsum for selective reduction, sulfurization and enrichment of valuable metals before matte smelting is proposed, and it’s identified that the key control factor of the gypsum sulfurization reaction is CaS conversion rate. The test conclusions can provide theoretical basis for the application of gypsum in matte smelting in the non-ferrous metallurgy field.

Abstract:The output of organically cobalt residue produced in the purification procedure in zinc hydrometallurgy is increasing year by year. Cobalt in the cobalt residue mainly exists in the state of organic chelate compound, which is insoluble in water and dilute acid. Therefore, the leaching rate of cobalt by conventional leaching method is very low. In line with the characteristics of such cobalt residue, this article comes up with a method of recovering cobalt from organically purified cobalt residue by employing a process comprising low-acidity leaching—calcining—reductive leaching—oxidizing cobalt precipitation. This process involves two innovation points. First, the calcination process is employed to destroy the organic components in the organic cobalt residue and convert it into easily recoverable CoO and CoSO₄; Second, in the cobalt oxide precipitation procedure, H₂O₂ is used as oxidizing agent instead of conventional Na₂S₂O₈ for oxidizing cobalt precipitation, to avoid a large consumption of oxidizing agent and cumbersome treatment of post cobalt precipitation liquor among other issues. Under the optimal process parameters of each procedure, the cobalt enrichment cobalt (Ⅲ) hydroxide (Co(OH)₃) obtained by this process contains 51.74% of cobalt, the cobalt enrichment ratio of the whole process is up to 9.5 times, and the comprehensive cobalt recovery is up to 87.42%, fulfilling the high-efficiency separation and recovery of cobalt from the organically cobalt residue in zinc hydrometallurgy.

Abstract:For many years, China has been the world’s largest producer and consumer of zinc.With the increasing pressure of energy conservation, environmental protection, and resource recycling requirements, it is imperative to promote technological progress and process innovation in the zinc industry. Based on a systematic overview of the status of zinc smelting process in China, this paper summarizes the technological innovation and application practice of zinc smelting process in the past decade. At present, the existing zinc hydrometallurgy process is gradually returning to the conventional leaching process, and is developing in the direction of large-scale equipment and harmless leaching slag, and slag treatment technologies such as side blowing submerged combustion bath smelting is developing rapidly. The hot acid leaching-hematite iron removal process has great development potential and has been industrialized. The production cost of the pressurized oxygen-enriched leaching process is still higher than that of the conventional process, which is suitable for enterprises with small demand for sulfuric acid and high transportation costs. The new high-efficiency zinc pyrometallurgical process has become the future development trend whether in primary ore smelting or in the recovery of zinc-containing secondary materials, because the high concentration and shortened flow, and it can effectively utilize the sensible heat of slag, reduce energy consumption and carbon emissions.

Abstract:Few researches have been made at home and abroad on the process of Cu & As removal from the post reduction solution in zinc hydrometallurgy. The commonly used process at present is Cu precipitation with Fe powder. However, this process is an impurity removal process with the largest consumption of hematite as auxiliary material and the highest cost, moreover, it has such disadvantages as large consumption of Fe powder, incomplete Cu & As precipitation and the Cu & As content in the post-precipitation solution being off standard, etc. In this paper, exploratory tests have been carried out on the process of Cu & As precipitation with hydrogen sulfide by using the post-reduction solution from a smelter in Yunnan Province as feed material, to study the influence of process parameters including hydrogen sulfide dosage, reaction time and temperature, etc. on Cu & As precipitation efficiency. The test results show that only the hydrogen sulfide dosage and the return amount of Cu residue crystal seed have relatively large influence on the Cu & As precipitation efficiency; the hydrogen sulfide dosage needs to be 1.2 times of the theoretical value to start the effective precipitation of Cu & As, and when it’s 1.4 times of the theoretical value, the precipitation efficiency of Cu and As is 99.95% and 98.45% respectively, which can meet the requirement of the acidic solution on Cu and As content; the return of Cu residue crystal seed can improve the Cu & As precipitation efficiency, when the excess coefficient of hydrogen sulfide is 1.2, Cu residue crystal seed of 5g/L is added into the solution, after reaction for 30min, the precipitation efficiency of Cu and As can reach 99.87% and 95.12% respectively. The exploratory tests indicate that the process using hydrogen sulfide to precipitate Cu & As in the post-reduction solution is feasible, its Cu & As precipitation efficiency is much higher than that of the Fe powder Cu precipitation process, thus, it deserves promoted application.

Abstract:The factors that influence zinc ingot quality include chemical composition and physical appearance. To tackle the low quality of zinc ingots produced from a zinc refinery, analysis has been made on the influence factors and control measures of chemical compositions such as Cd, Cu, Pb and Fe, from the perspective of zinc electrolysis principle and the various electrolysis procedures, and measures has been taken to control the physical appearance quality of zinc ingots in every detail of zinc ingot casting operation. As a result, the yield of 0^# zinc reaches 100%, the scrap percentage is lowered to less than 1% and the highest quality of zinc ingots reaches 99.997% or more, whereby good economic benefits are achieved.

Abstract:With the nickel concentrate from xxx company as raw material and by reference to the study results and production practice of the chloridizing refining process at home and abroad, the feasibility of adopting the chloridizing leaching-solvent extraction-electrowinning process to produce high-quality cathode nickel has been verified in a laboratory. The test results show that as the nickel concentrate is subjected to Cu replacement and precipitation by adding anode slime, followed by chlorine leaching, under the condition of preferable process parameters, the Cu replacement & precipitation rate is up to 99.8%, and during the chlorine leaching, the leaching rate of Ni, Cu, Fe and Cu reaches 96.02%, 100%, 100% and 63.33% respectively; as the solution after Cu replacement further goes through Fe removal by using hematite method, followed by N235-P204 combined extraction, under the condition of preferable process parameters, the Fe content in the solution after Fe removal is only 0.0031g/L, the contents of ionic metal impurities, except Pb ion, in the raffinate can meet the requirement of the purified solution for electrowinning; the raffinate is further subject to Pb removal using the chlorine+nickel carbonate method, the solution after Pb removal contains Pb of 0.0001g/L, under the condition of preferable electrowinning process parameters, cathode nickel with a purity of 99.99% can be produced.

Abstract:The copper anode slime and the acidic slime from Pb-Zn smelter are the main source for Se resources recycling, the current commonly used pyrometallurgical and hydrometallurgical recovery processes have the disadvantages of incomplete separation of Se and Hg or high cost for slag/residue treatment. In this article, the acidic Se-Hg slime of a lead refinery is used as raw material to conduct a Se-Hg separation test by means of POX alkaline leaching, with the following results: under the conditions of alkaline use being 1.2 times of acidic slime (dry basis), oxygen pressure being 2.0MPa, temperature being 180℃, liquid-solid ratio being 3∶1 and reaction time being 2.5 hours, the Se leaching efficiency is as high as 99% or more and the Hg slag solidification efficiency is 98% or more. And 98% crude Se can be obtained by purification, impurity removal and reduction of the alkaline leaching liquid. This technology can be used to safely and effectively separate Se and Hg in acidic slime, the neutralized residue can be subject to dilute acid leaching and returned to Pb system for Pb recovery and the sulfurized residue can be returned to the POX alkaline leaching system for Se recovery adding to the total Se recovery. In addition, in this method, the elemental Hg in the acidic slime is converted into Hg oxide that is not volatile under normal temperature, avoiding pollution of Hg during storage and transport.

Abstract:Methylchlorosilane in trichlorosilane is an important cause of excessive carbon impurities in polysilicon. In order to deeply remove methylchlorosilane in chlorosilane, this paper detects and analyzes the content of methylchlorosilane in each process of trichlorosilane hydrogen reduction method, and studies the conversionrules of methylchlorosilane impurities. The results show that there is a conversion equilibrium relationship between MDCSand MTCS in the hydrogenation system; In the reduction system, MDCS will be converted into MTCS, and the relative conversion amount is basically the same according to the content of MDCS in the incoming and outgoing streams;in the anti disproportionation system, methylchlorosilane will not be converted, and it can be inferred that methylchlorosilane needs to be converted under appropriate temperature and pressure;the purification system is the transfer and separation process of methylchlorosilane components,and properly organizing the purification tower to purify the methylchlorosilane is beneficial to the convertion of MDCS in TCS.

Abstract:A smelter in Guangxi Province uses pyrometallurgical process to treat jamesonite, and the granulated slag of blast furnace contains large quantity of Zn, In, Sn, Sb and other valuable metals.To effectively recover these valuable metals, the company decided to build a 2.5m² fuming furnace. Given the fact that traditional fuming furnaces have the disadvantages of easy floating fire bricks that require frequent maintenance and big center height of tuyeres which is not beneficial to reduction smelting, the company has redesigned a new type of fuming furnace with hearth by taking a series of measures, for instances, converting the furnace bottom structure into a hearth, optimizing the furnace dimensions, modifying the tuyere device and water jacket lining, etc. The new type of fuming furnace can not only be used as a fuming furnace to treat blast furnace slag, but also be used as a blast furnace to treat zinc alloy ore. When being used as a fuming furnace, by assuming a daily treatment capacity of 60t/d of Pb-Sb blast furnace slag, this fuming furnace can recover 1.73t of Pb, 1.89t of Sb, 4.6t of Zn, and 8428g of In per day, with remarkable economical benefits. The successful design and application of this fuming furnace with hearth is the extension and perfection of jamesonite pyrometallurgical process, which has blazed a new trail for comprehensive recovery of Zn, In, Sn, Sb and other valuable metals; further more, its production operation is stable, therefore, it has the value to be widely used.

Abstract:Some batches of the incoming copper raw material of a smelter in Yunnan Province contain resin powder. As resin has good acid and alkali resistance, it barely reacts with any acid and alkali solvents, thus, when the acid dissolution iodometry is adopted to measure the Cu content in the resin-bearing copper raw material, such problems exist as incomplete dissolution of the sample, repeatability and accuracy of the analysis results unable to meet the requirement. In this paper, the sample is first subject to solidification at 200℃, carbonization at 500℃ and ashing at 900℃, followed by assay and analysis using the acid dissolution iodometry. The test results show that under strictly controlled ashing temperature and time, the resin structure in the sample is completely broken, effectively avoiding the incomplete dissolution of the sample; the relative standard deviation (RSD, n=5) of the measured result is 0.20%-0.41%, the relative error (RE) is 0.06%-0.27% and the standard recovery is 99.01%-101.16%, indicating that the method results in good precision and accuracy and high recovery, thus, it can be used to measure the Cu content in resin-bearing copper raw material.

Abstract:In view of the problems of jarosite slag, such as the large amount of jarosite slag stockpiled in the plant, and the routine treatment process with high investment, high operating cost and low economic benefit, a lead-zinc smelter explored the process route of two stages weak acid leaching-washed slag making bricks after long-term research and laboratory tests. The filtrate and washing slag water in the process can be returned to the system for recycling, and the zinc sediment slag is returned to the zinc hydrometallurgy system, and the washed slag is used to make bricks. By improving the traditional brick-making process and material ratio, the compressive strength of pressed non-fired brick reaches MU15 after 28 days of curing, which exceeds the national standards, and the qualified rate of products increased from 37.3% to 98.63%. After the project was completed and put into operation, the average annual total cost was CNY 25.798 million, the annual income was CNY 39.159 million, and the positive economic benefit of jarosite slag was CNY 13.361 million. The reformed process has the advantages of less investment and low cost, and the bricks are not easy to collapse. It is a new type of environmental protection material with high market recognition, and the process is worthy of promotion in copper, lead and zinc smelting enterprises.

Abstract:In the process of zinc hydrometallurgy, most of indium in zinc concentrate is left in the neutral leaching residue. Compared with other In recovery processes, the In replacement & precipitation method boasts such advantages as small amount of In precipitation residue and high In content in the residue; however, the Fe content in the neutral leaching residue is relatively high, the solution after In precipitation needs for Fe removal treatment. To realize high efficient In enrichment and Fe resource recovery, neutral leaching residue and leachate are used to carry out experimental study on the process of In replacement & precipitation with zinc powder and the process of hematite Fe removal from the solution after In precipitation. The results show that the preferred In precipitation conditions are endpoint pH=4.0, reaction temperature at 80℃, zinc powder dosage of 8g/L and reaction time lasting 1.5h, under such conditions, the average precipitation efficiency of In is 97.23%, the In content in the residue is 2.15%; the preferred hematite Fe removal conditions are reaction temperature at 200℃, reaction time of 180min, oxygen partial pressure of 0.3MPa, under such conditions, the precipitation efficiency of Fe is 97.12%, the Fe and S contents in the residue are 60.37% and 1.84% respectively. The Fe precipitation residue (hematite residue) can be sold as raw material to cement plants.

Abstract:There is a large stockpile of sulfur flotation tailings in a refinery in Qinghai, which contain 2%~3% of Zn, more than 10% of Pb and about 30% of Fe. To address this issue, this plant has adopted, as supporting measure, the pyrometallurgical + hydrometallurgical process to harmlessly treat the tailings. The tailings and hot filtration residue are mixed, pelletized, and smelted in an oxygen-enriched side-blowing furnace, the smelting slag is then fed into a fuming furnace to be volatilized, and the Zn hypoxide is enriched to enter off-gas dust; the produced Zn hypoxide is subject to two stages of leaching plus extraction process to recover Zn and other valuable metals. In this process, the recovery of zinc in off-gas dust is about 80%, that of indium about 75%; the off-gas dust from side-blowing furnace can be recovered and treated; the smelting slag from the fuming furnace can be used to make cement or eco-friendly bricks; the leaching liquid from hydrometallurgical process is returned to the hydrometallurgical system for zinc; the enriched metals and leaching residue can be sold,in this way, the objective of green metallurgy can be realized.

Abstract:The impurity content of smelting raw material in a Pb-Zn smelter gradually increased, the former “lime-iron salt” process to treat heavy metal wastewater no longer meets the reuse requirements, especially with the thallium content going far beyond the limit. Therefore, the existing wastewater treatment process was upgraded and reconstructed, the process of heavy metal wastewater biologicals for advanced treatment and coordinated thallium removal were introduced into the plant. When using this process to treat Pb-Zn wastewater,the better process conditions are stabilizer 0.7mL/L and biologicals 0.7mL/L for the primary treatment system, and stabilizer 0.3mL/L and biologicals 0.3mL/L for the secondary treatment system; after treatment under these conditions, the content of heavy metals and thallium in the effluent is all stable and in compliance with the discharge standards. This process has been stably operated for two years, saving wastewater treatment cost by 5.2 million CNY each year, the goal of resource utilization and reduced discharge has been reached; it has also reduced the environmental risks and provided technical support for bio-environmental governance, and has larger application value.

Abstract:In China, the existing cemented carbide recovery technologies have the disadvantages of heavy environmental pollution, high requirements for equipment,high production costs, etc., and the quality of only a few products can be up to the world average level, resulting that the stockpiled amount of waste cemented carbide has been increasing geometrically. In view of the fact that the tungsten and cobalt resources are scarce in China, the development of a new, high efficiency and short-route waste cemented carbide recovery process is of great significance. In this article, the main methods for waste cemented carbide recovery in China and abroad are summarized, the recovery technology of low temperature water solution in electrochemical method and the recovery technology of high temperature molten salt electrodeposition and the relevant applications are elaborated; and finally, the detailed analysis is made for the route of joint process of these two technologies.The article points out that this technology can remedy effectively the shortcomings of single electrochemical recovery process, and can improve the alloy separation efficiency and product quality; it shows that in the future, the way of “electrochemical method is the mainstay, combined with various processes and methods” will be the major hot research direction for treatment and recycling of waste cemented carbide.

Abstract:To tackle the difficulty in the leaching of refractory Cu-Co alloy, the process of a primary direct acid leaching + a secondary oxidizing acid leaching is adopted for single-factor test, and the influence of each factor on the leaching rate of Co, Cu and Fe is studied. The test results show that the optimal process conditions of the primary leaching are a sulfuric acid concentration being 2mol/L, a reaction temperature at 85℃, an agitation speed of 200r/min, a liquid-solid ratio of 1∶10g/mL and a reaction time of 105min; the optimal process conditions of the secondary leaching are a reaction temperature at 85℃, an agitation speed of 200r/min, a liquid-solid ratio of 1∶10g/mL, sodium chlorate being used as oxidizing agent at a dosage of 30% and the initial acid concentration being 3mol/L, and reaction time lasting 4h. Under such conditions, the relatively high leaching rate of Co, Cu and Fe can be obtained, which are respectively as 95.47%, 96.62% and 96.01%. A unreacted core model is used to characterize the excellent imitative effect of the two-stage Cu-Co alloy leaching process, internal diffusion is the restriction factor of the reaction, the apparent activation energy during the leaching process is within the distribution range of 5~20kJ/mol. In the secondary leaching, the activation energy of Co and Cu is increased by 1.721kJ/mol and 8.888kJ/mol respectively while that of Fe is decreased by 10.186kJ/mol.

Abstract:冶金渣经过改质还原并回收金属铁元素后，利用剩余熔渣直接制备成微晶玻璃等高附加值材料，是实现冶金渣高效低碳资源化的有效途径之一。提取金属铁后的熔渣多以CaO-SiO₂-MgO渣系为主，通常还需要补充适量Al₂O₃来改善微晶玻璃相关性能。本文通过向CaO-SiO2-MgO三元玻璃体系中引入不同比例Al₂O₃，来研究其对微晶玻璃抗弯强度和析晶动力学的影响。结果显示，微晶玻璃抗弯强度主要受烧结收缩率影响，在Al₂O₃为15%时，以钙长石为主晶相的微晶玻璃抗弯强度达到最大值；随着Al₂O₃含量增加，玻璃固相开始熔化温度Ts和液相开始析晶温度Tl逐渐降低，析晶峰温度Tc和析晶活化能Ec逐渐升高，而析晶速率常数k(Tc)和晶化指数n没有明显变化。研究结果说明，随着Al₂O₃含量的增加，玻璃烧结阻力降低，析晶阻力增加。