China Nonferrous Metallurgy

Abstract:The coal mainly thermal power generation is the main energy supply method; however, the use of coal resources has the issues of nonrenewability of resources, large emission of carbon dioxide, severe environmental pollution, etc. The solid oxides fuel cell (SOFC) has the advantages of high onetime power generation efficiency, ecofriendly products and so on, which is recognized as one of the revolutionary green energy technologies in the 21st century. In this paper, review is made around the aspects of future development direction of SOFC system, the performance of the zirconium oxide based, cerium oxide based and perovskite based electrolyte material in the SOFC system, which points out that the scandium resource based zirconium oxide electrolyte material is the current optimal route for industrial production of electrolyte material. China has obvious advantage in scandium resource reserves, the supply of scandium resource can ensure the sustainable and safe development of the fuel cell new energy industrial chain, therefore, it is suggested that efforts be made in the national level to strengthen the policy guidance to all links of the resource supply chain, processing chain of manufacture industry, product application chain and recycling chain, and to make good top tier design to speed up the fostering of SOFC industry and firmly grasp the wave of the new generation of industrial energy transformation.

Abstract:The traditional rolled anode plate has the problems of short service life, high cost, low intensity, etc., the new fence type aluminum based composite anode plate of Pb-0.3% Ag-0.12% (Ca+Sr) is developed, which has reduced the anode plate cost and improved the strength and corrosion resistance of anode plate. To realize the industrial application of this new type of composite anode plate, further optimization is made for it. By means of pilot test, by comparison of 15d electrolysis production indicators, anode slime etc. between traditional anode plate and fence type coated anode plate of different flat wire widths, and comparison of the cathode zinc products of the fence type coated anode plate of different bar clearances, the following conclusions are obtained: compared with the traditional anode plate, the narrow strip fence type coated composite anode plate can make large improvement in electric current efficiency, cell voltage and cathode zinc quality; the narrow strip anode plate has larger effective active area than that of wide strip, however, in the later stage cleaning of anode slime, it is more difficult to clean narrow strip anode plate, which is prone to bending; the too large bar clearance of fence type coated composite anode plate will result in the appearance of “#” traces on the cathode zinc, affecting the output and electric efficiency, the proper bar clearance is 9~14mm.

Abstract:Quite a large quantity of carbon dross is produced in aluminum electrolysis, about 5~15kg/t of Al. At present, the main methods for treating carbon dross are flotation process and crucible furnace smelting process, and these two methods have their respective advantages and disadvantages in disposal cost and electrolyte purity, but all have the issue of producing carbon slime (hazardous waste) in the disposal process. On the basis of the DSC-TG data analysis for carbon dross, the carbon dross low temperature circulating roasting process is put forward to recover electrolyte and avoid producing carbon slime at the same time. The roasting test result shows that using this process to recover electrolyte from carbon dross is technically feasible, after two times of circulating roasting under the roasting temperature of 750℃, the comprehensive carbon removal rate can be as high as 97.6%, the main component of the carbon dross after circulating roasting is electrolyte (cryolite). This process can successfully avoid producing carbon slime, which provides a new idea for the reduction and resourceoriented disposal of carbon dross. However, the production capacity of aluminum electrolysis is subjected to limitation, the future needs for electrolyte for the startup of electrolytic cell will be less and less, the development and use of the recovered electrolyte will be the next step issue to be contemplated by research fellows in aluminum industry.

Abstract:Coke, as a reductant in electric furnace smelting of Tislag, has a certain influence on the Tislag smelting process and the product quality. The Xichang coke is taken as the benchmark reductant, analysis on the basic properties of Panjiang coke and Xichang coke is made. By combining the field use of the two kinds of coke, the impact of Panjiang coke on the Tislag smelting of Panzhihua titanium concentrate is studied. The result shows that the graphitization extent of Panjiang coke is 10.83% higher than that of the Xichang coke, it has larger microcrystal volume, with small ratio of corresponding surface active carbon elements to the total carbon elements, so that the reactivity of Panjiang coke is lower than that of Xichang coke. Although the fixed carbon content and particle size distribution of Panjiang coke are superior to those of Xichang coke, the reactivity and structure of the former are inferior to the latter, in some extent,compared with the Xichang coke, the carbon proportioning of Panjiang coke is increased in the reduction of smelting Tislag of Panzhihua titanium concentrate, with higher power consumption per ton material and lower Ti grade of the Ti slag.

Abstract:The flow field velocity in rare earth electrolytic cell is not stable, the flow outside the anode is far too slow, which is not beneficial to the full electrolytic reaction and the improvement of electrolysis efficiency. The existing study shows the flow status in the electrolytic cell can be controlled by applying external magnetic field to agitate the electrolyte. In this paper, simulation is conducted of the electromagnetic agitation for the 8kA rare earth electrolytic cell, and design is made that copper coils of various ampere turns are put outside and at the bottom of the electrolyte, then by using the softwares of Ansoft Maxwell and Ansys Fluent, the finite element analysis and simulation are conducted for the magnetic field generated by electrolyte and the flow fieldis subjected to electromagnetic agitation, the following conclusions are got: the addition of coils on the lower part of the side cannot generate electromagnetic agitating force in a certain ampere turns; for the coil added on the upper part of the side, the wave form is sine wave, the ampere turns of the coil needed are less than those of the bottom, and the flow field stability is better; the needed ampere turns of the coil added at the bottom are far more than those on the upper part of the side, and compared with the position at the upper part of the side, the flow status in the cell subjected to electromagnetic agitation is more complex and chaotic.

Abstract:Quite a large quantity of magnesium reduction slag is generated in the Pedgeon process of magnesium smelting, during the stockpiling process of the slag, such issues as soil alkalization and hardening, etc. will arise, as for its disposal and consumption, it is mainly used for producing cement, buildinguse brick and desulfurization agent, with low comprehensive use value. The process route of ammonium chloride leaching of magnesium reduction slag are put forward. The process can be used to extract and separate calcium, silicon and other elements in the magnesium reduction slag, to make the magnesium slag become the calcium source and silicon source, so as to achieve the zero emission and high value utilization of the magnesium slag. In this paper, aiming at the leaching procedure in the process, the calcium leaching efficiency and the phase of leaching residue under various singlefactor conditions are studied, and the following conclusions are obtained: the ammonium chloride is able to make selective leaching for the calcium in the magnesium reduction slag, the leaching efficiency is closely related to reacting temperature, ammonium chloride concentration, liquidsolid ratio, etc.; the leaching efficiency increases with the increase of ammonium chloride concentration and liquidsolid ratio, it increases first and then decreases with the rising temperature; the better leaching process conditions are as follows: reacting temperature of 25℃, ammonium chloride concentration of 15%, and liquidsolid ratio of 40∶1, under which, the calcium leaching efficiency can be as high as 88.7%; the phase of the leaching residue is mainly composed of magnesium oxide, calcium carbonate, silicon dioxide and other substances, from which the purer siliconbearing raw material can be got by scrubbing process.

Abstract:The crude nickel sulfate produced in the process of recovering nickel from copper electrolyte has the problem of high impurity content, resulting in a low added value of the crude nickel sulfate, thus, requiring a secondary impurity removal. A copper smelting enterprise used P204 to carry out an extraction and impurity removal process test on crude nickel sulfate solution, and optimized and improved the issues of high nickel loss rate and serious emulsification in the test with excellent results. The P204 extractant was saponified with sodium hydroxide, and the sodium soap was used for extraction of the crude nickel sulfate solution. The extraction rates of iron and zinc were all above 99.9%, and the nickel loss rate was 12.26%. In the saponification process of P204, the loss of nickel could be decreased by converting sodium soap into nickel soap. When nickel soap was used for extraction of the crude nickel sulfate solution, the extraction rates of iron and zinc were still above 99.9%, and the loss rate of nickel was lowered to 0.4%. The emulsification issue in the extraction process can be solved by controlling and purifying the crude nickel sulfate solution and controlling the pH value of the feed solution.

Abstract:The biggest advantage of the zinc pressure oxidative leaching process is that the byproduct is solid sulfur instead of sulfuric acid, which can fundamentally solve the problems of slow sales of sulfuric acid and SO2 pollution caused by traditional processes. A zinc company utilized the zinc pressure oxidative leaching process in its production. When the sulfur recovery process was carried out in the initial stage, the sulfur recovery was low, with most of the sulfur having not been effectively recovered but brought to the tailings, resulting in the loss of sulfur and the difficulty of tailings treatment. Subsequently, the company systematically analyzed the pressure oxidative leaching process, and improved the sulfur conversion rate during the pressure oxidative leaching process by regulating the process parameters and increasing the particle size of the sulfur concentrate in the secondstage leaching residue, and improved the sulfur recovery rate in the flotation process by controlling the slurry concentration, slurry particle size, and air volume of the flotation cells, and increased the sulfur recovery rate in the subsequent procedures by standardizing the filtration operation and ensuring the temperature of the molten sulfur tank. After the company took such improvement measures, the total sulfur recovery rate increased from 45% to 71%. The specific methods can provide reference for other similar enterprises to improve their sulfur recovery rate.

Abstract:In China, zinc smelting is mainly based on the traditional "roastingleachingpurificationelectrolysiscasting" process. Due to the lack of zinc resources, the raw material for zinc smelting is mainly high iron sphalerite. In the process of smelting, zinc ferrite is inevitably generated. Due to the relatively stable nature of zinc ferrite, the leaching rate of zinc is reduced, which not only wastes zinc and iron resources, but also seriously pollutes the environment. Based on the above, zinc concentrate of a zinc smelter in Guangxi is taken as the research object, and the process of carbon roastingleaching is adopted to reduce ferric ion into ferrous ion, so as to prevent the generation of zinc ferrite and improve the leaching rate of zinc. The characteristics of raw materials were analyzed by determining element content with Xray fluorescence spectrum (XRF). The effects of proportion of carbon, roasting temperature, roasting time, type of carbon and leaching method on the leaching rate were studied in order to determine the optimal process conditions of carbon roastingleaching. The study results show that the best process conditions of zinc concentrate roasting with carbon are as follows: roasting temperature 950℃, roasting time 1.5h, carbon ratio 3%, under the above conditions, the leaching rate of 84.39% can be obtained by using activated carbon, the leaching rate of carbonfree roastingleaching is only 65.32%; the ferric ion can be reduced into ferrous ion by roasting with carbon, which can effectively prevent the formation of zinc ferrite and improve the leaching rate of zinc; by acid reverse leaching, the leaching rate of zinc with reduced coal can reach 78.42%, which is much lower than that of conventional leaching, therefore, the conventional leaching process is more suitable for the carbon roastingleaching process than the acid reverse leaching process.

Abstract:The coarse bulk primary silicon structure, lathlike or needlelike eutectic silicon structure and αAl grains in the AlSi cast alloys seriously weaken the mechanical properties of the alloys. Currently there are many introductions on the research status of the modification of P, Sr, Na or single rare earth elements, but there is a lack of systemic summary of rare earth composite modification research. The paper systemically introduces the rare earth composite modification technology of AlSi cast alloys, and expounds the rare earth modification of primary silicon and eutectic silicon and the rare earth refinement mechanism of αAl grains, respectively, systematically introduces and summarizes the effects of rare earth composite modification of AlSi cast alloys on the microstructures such as primary silicon, eutectic silicon, αAl grains, as well as their compressive strength, elongation, wear rate, roughness, corrosion resistance among other properties, expounds the application status and market prospect of rare earth modification technology of AlSi cast alloys, and summarizes and gives an outlook of the rare earth modification technology of alloys.

Abstract:A large number of rare earth resources exist in tailings and industrial waste residues, the grade is low, but the total amount is considerable. Using biological leaching technology to extract rare earth elements from low grade rare earth resources is a lowcost and environmentally friendly green metallurgical process. The process adopts the microorganisms including bacteria and fungi, the different microbial leaching of rare earth elements and the mechanism of action between microbes and rare earth elements are described, showing that the current method using microbial leaching ore extraction of rare earth elements also has certain limitations, mainly including complexity of metal elements, difficult separation of rare earth elements and single rare earth element; lower rare earth content than those of inorganic acid and organic acid leaching; microorganisms prone to decay or even die under the condition of high rare earth concentration. At last, it is pointed out that the extraction technology of rare earth elements is developing towards the reduction, harmlessness, resource recovery direction. The combination of biotechnology and extraction technology provides an economical and feasible method.

Abstract:Affected by the national industrial policies, only half of the 500kA electrolytic cell series of the production line of a certain aluminum plant is allowed to be put into operation. Due to that the busbar of the temporary circuit is close to the endcell of the semiseries, and the affect of magnetic field is severe, the electrolysis series cannot be started up normally. This company made bold innovation, by means of reasonable ratio of coke to crushed graphite, prolonged roasting time, using electrolyte powder as startup material and other process improvement, and by installing soft connector, reasonably removing shunt, increasing busbar transfer, large flux continuous aluminum filling and other operation technologies, the two next to the last electrolytic cells are started up successfully, achieving annual economic benefit of 14.06 million CNY. As the startup of the electrolytic endcell is difficult with quite a lot of special measures, refined management is needed. In this paper, the startup of the 500kA endcell of the semiseries of the company is elaborated for the purpose of providing a reference to the similar plants.

Abstract:The waste heat boiler in smelting plant can not only recover waste heat but also collect dust in hot offgas, recover valuable metals and reduce dust content in offgas, however, if there is severe coking in the operation, it will shorten the maintenance interval and affect the production. A certain company used to remove the coking by worker entering the manhole, resulting the issues of large labor intensity and inconspicuous decoking effect. Based on the above, the company took the measures of updating the structure of the radiation zone of boiler, improving the form and moisture content of inlet material, adding coking depressant, using boiler spray technology, etc. to control boiler coking, and obvious results were achieved. The boiler maintenance interval is increased from 30 days to 40 days, the amount of cleared coking is reduced from 20~25t to approximately 10t, and the clearing time is reduced from 48h/month to 6~7h/month. The successful transformation of the boiler system can provide a reference to the similar plants.

Abstract:The content of barium sulfate in copper anode slime is of great significance to the further metallurgical treatment of copper anode slime. At present, the commonly used barium sulfate measurement methods include turbidimetry, spectrophotometry, inductively coupled plasma spectroscopy, etc. When the sample composition is relatively complex, general measurement methods tend to convert barium element into barium carbonate precipitate and then into the form of soluble barium salt for measurement. In this paper, by taking advantage of low solubility of barium sulfate, a saturated solution of hydrochloric acidammonium bifluoridenitric acid potassium chlorate is used to dissolve the coexisting substances of barium sulfate, and then the content of barium sulfate in the sample is determined by gravimetric method. The test results show that the detection limit of barium sulfate in this method is 9mg. When the content of barium sulfate is between 8% and 15%, the relative error is not greater than ±3%, which can meet the requirements of production control. This method provides a new idea for measurement of barium sulfate.

Abstract:Red mud is solid waste from the process of alumina production, most of which is treated by stockpiling, its treatment and utilization is one of the major topics facing the aluminum industry. In this paper, By using red mud of Bayer process as the main raw material, together with fly ash, ceramic polishing waste powder and other materials, the building insulation material is prepared with sintering process. The result shows that under the relatively optimum conditions of 40% of added red mud, 1070℃ of sintering temperature and 3% of foaming agent dosage, the performances of the prepared products can reach the relevant code requirements of the industry. By using this technology, not only the red mud can be treated and utilized in large scale, but also the ceramic polishing waste powder and other industrial solid waste can be fully made use of, blazing a new path for utilizing the multisolidwaste in a synergistic way.

Abstract:Coal ash leaching test was conducted using sulfuric acid, for the purpose of investigating the influence of the main process conditions on the leaching rate of Al and Fe in the coal ash, meanwhile the compositions and phase of the leaching residue were analyzed. The test results showed that: hightemperature acid leaching of coal ash using sulfuric acid could achieve a highefficiency leaching of aluminum and iron elements, and the leaching temperature was the main influencing factor; under the acid leaching conditions of leaching temperature 230℃, sulfuric acid mass fraction 20%, reaction time 120min, and liquidsolid ratio 10∶1, the leaching rate of Al was 89.43%, and the leaching rate of Fe was 69.78%; the main chemical composition of the acid leaching residue was SiO₂, its content was 79.1%, and it also contained a small amount of unleached Al₂O³ and Fe₂O₃ which could be used as raw materials to prepare Portland cement clinker. There was no secondary waste residue discharge in this test, and no waste liquid discharge in the subsequent treatment of the leachate. The method provided a reference for realization of comprehensive utilization of coal ash with zero discharge.

Abstract:In order to study the photocatalytic performance of industrial titanium dioxide composite materials, this paper used titanium dioxide as the matrix and successfully prepared Bi2O3titanium dioxide and Bi2O3titanium dioxide/PAC supported composites by hydrothermal/primary calcination method. The photocatalytic properties of titanium dioxide, Bi2O3titanium dioxide and Bi2O3titanium dioxide/PAC supported composites were studied. The results show that the adsorption effect of titanium dioxide on methyl orange is relatively limited, the removal efficiency is low, and the removal effect of photocatalytic oxidation reaction can reach 81.3%; when the molar ratio of Bi to Ti is 12%, Bi2O3titanium dioxide/PACsupported The composite material has the best photocatalytic degradation effect on methyl orange, up to 87.5%; in comparison, the adsorption effect and photocatalytic degradation effect of the three materials on methyl orange is the best is Bititanium dioxide/PAC, the adsorption rate is 41.3%, and the photocatalytic degradation efficiency is 89.7%.

Abstract:At present, dechlorination of zinc oxide for dust collection mainly adopts fire method dechlorination in China, which has many disadvantages, such as large equipment investment, large cleaning workload, environmental pollution. Zinc oxide for dust collection in zinc hydrometallurgy has high chlorine content and cannot be directly reused in the wet system. Based on the above, the two wet recovery schemes of zinc oxide water washingwater washing solution zinc precipitation and zinc oxide acidic leachingacid leaching solution copper residue dechlorination were studied, and the test results of the two schemes were compared and analyzed, and the wet recovery process parameters were optimized.The results show the zinc oxide water washingwater washing solution zinc precipitation scheme has the problems of low decolorination efficiency, bad zinc precipitation effect, etc.; and zinc oxide acidic leachingacid leaching solution copper residue dechlorination scheme has the advantages of good decolorination, high zinc recovery rate and low cost, and it is proved that the process is feasible.

Abstract:The solubility of ZnO in the system of ChClurea is high, which makes it possible to realize selective dissolution and effective separation of ZnO, the physical properties of ChClureaZnO system impose large impact on the solubility of ZnO, while the solubility of ZnO has remarkable influence on the separation and extraction process. Within the temperature range of 323~363K, the viscosity, conductivity, density and surface tension of the ChClureaZnO system are measured respectively, and the impact of temperature and ZnO concentration on its physical properties is studied. The result shows that within the temperature range of 323~363K, the viscosity of the ChClureaZnO system is 20~200mPa·s, conductivity 0.2~0.8S/m, density about 1.20g·cm³ and surface tension 50~80mN/m; with the temperature rise, the viscosity of the system becomes lower, the conductivity becomes higher, and the relationship between the conductivity and viscosity meet the Walden law; the density and surface tension gradually get lower with the temperature rise; the viscosity, conductivity, density and surface tension of the ChClureaZnO eutectic solvent increase with the increase of the ZnO concentration in the system.

Abstract:In order to investigate the adsorption capacity of heavy metal Pb(Ⅱ) from agricultural and forestry waste walnut shell, modified walnut shell biochar was prepared by microwaveH2O2 coupling modification method, and analyzed by scanning electron microscope, Xray diffraction and infrared absorption spectrum. The effects of pH, adsorption time, temperature, amount of adsorbent and initial concentration on the adsorption of Pb(Ⅱ) from simulated aqueous solution with modified walnut shell activated carbon were investigated. The characterization results showed that the modified biochar had amorphous carbon structure, uneven surface of carbon particles and abundant pore structures of different sizes and shapes. The contents of C[FY=,1]O, C—O, C[FY=,1]C groups increased compared with those before modification. Under the conditions of initial ion concentration of 400mg/L, dosage of 16mg/L, pH 4.0, temperature of 25℃ and adsorption time of 180min, the adsorption rate of Pb(Ⅱ) by modified biochar reaches 99.5%. The results of adsorption experiments show that the microwaveH2O2 coupling modified walnut shell biochar has good adsorption effect on high concentration Pb(Ⅱ)containing wastewater.

Abstract:The leaching and leaching kinetics of Cobalt in lowgrade copper ores of Africa were studied and the mechanism of reduction leaching of associated cobalt was discussed from the perspective of thermodynamics. The results show that increasing the amount of reducing agent, sulfuric acid, leaching temperature and liquidsolid ratio can improve the leaching rate of cobalt, and speedup the process of leaching. The leaching equilibrium of cobalt can be achieved in about 1hour. The dissolution behavior of cobalt in lowgrade copper ores coincides with the mixed kineticshrinking core model, which is based on the interface transfer and diffusion across the solid layers. The activation energy is determined to be 13.42kJ/mol and the kinetic equation can be expressed as follows: 13ln(1-x)+(1-x)-13-1=0.0025m0.8688r0.1974N1.0147e-13.42RTt. It provides a theoretical basis for improving the leaching rate of associated cobalt in practical production.