China Nonferrous Metallurgy

Abstract:This paper first discusses the development background of China’s copper industry, and points out that the industry is facing a series of problems such as low self-sufficiency rate of resources, equipment conditions to be improved, and a greater say required in the international copper market. Secondly, taking the characteristics of carbon emissions in the sector into consideration, it is proposed that, apart from copper smelting companies, due attention shall be also be given to the carbon emission reduction of other mining companies, and directional suggestions are given for the carbon emission reduction paths. Thirdly, under the guidance of the “2-stage carbon reduction” goal, the following opportunities and challenges faced by China’s copper industry are analyzed: copper consumption driven by the development of alternative energy source industry, increasing proportion of recycled copper driven by green circular economy, intensified competition pressure brought by industrial transformation & upgrading and yield distribution adjustment. Finally, based on the above analysis, suggestions for low-carbon development of copper industry are given for reference by relevant authorities.

Abstract:ESG evaluation system started to develop in China since 2018. It consists of three dimensions: ESG information disclosure principles and guidelines, enterprise ESG performance rating and ESG investment guidelines. Non-ferrous metallurgy industry has many risks at the ESG level, such as environmental issues, safety production accidents, occupational health problems, community complaints, poor risk control ability, weak internal control management and so on. These potential ESG risks have brought great challenges to the non-ferrous metallurgy industry to achieve carbon reduction goals and sustainable development. Under the background of “carbon peak and carbon neutrality” Goal set by industry and the nation, the discussions is made in this paper on the ESG system’s development status and its role in promoting the green and sustainable development of nonferrous metallurgy industry. It concludes that the ESG evaluation indicators shall draw some attention from nonferrous metallurgy industry, and practical suggestions are given on how to utilize ESG system in a better way to support the green & sustainable development of the industry.

Abstract:This paper analyzes the variation trend of nickel and cobalt prices from 1980 to 2020, and points out that the force influencing the market has gradually shifted from Europe, America and Japan to China. By 2020, China’s nickel output and consumption account for 30.6% and 58% of the world’s nickel output and consumption respectively, and 72% and 56% of the world’s output and consumption respectively as for the cobalt. China has already taken the leading position in the global nickel and cobalt market. In the future, with the rapid development of new energy vehicles, the consumption prospect of nickel and cobalt is very optimistic. The United States, South Korea and other countries have paid their attention to the supply chain security of battery metals including nickel and cobalt. China is highly dependent on imports in nickel and cobalt resources, and the complete industrial chain from smelting to materials can partially make up for the resource shortage, but the status quo of resource enclaves is difficult to change. It is suggested that the relevant authorities further strengthen the follow-up research on the nickel and cobalt industry, and take a variety of measures to ensure the raw materials supply of nickel and cobalt and to be better prepared for the new era of the global nickel and cobalt market.

Abstract:In this paper, the decomposition and volatilization of Sn, SnS, Cu, Cu₂S and their mutual reaction ΔG-T under different conditions are calculatedby using tclassical thermodynamic calculation method, as well as the stats such as saturated vapor pressure of tin. The theoretical experimental conditions of decomposition, volatilization and mutual reaction of Sn, SnS, Cu and Cu₂S are studied through data analysis and discussion as following: the decomposition temperature and pressure of SnS(s, l) are negatively correlated, and the decomposition reaction of SnS(s, l)does not occur in the standard conditions, and the decomposition reaction of SnS(g) is impossible; the decomposition temperature of Cu₂S s, l) is negatively correlated with the pressure; In standard conditions, when the temperature is higher than 690K (about 417℃), SnS reacts with Cu; In vacuum, Cu₂Sand Sn react easily.

Abstract:The end time of copper matte converting is usually determined on the basis of the status of off gas, fire, splashed matter, and detecting rods. Such determination is largely based on the operator’s subjective opinion, which could lead to under-converting or over-converting. A mathematical model can be established of the whole converting process through the METCAL system using mass balance, heat balance and elemental balance. By analyzing and calculating process parameters and controlling the quantity and timing of cold charge, the end time of slagging and copper production can be determined. The paper describes in detail the process of establishing the model and treating errors; the modified simulation model indicates that the error of determining the end of the slag-forming period can be controlled within ±5%, and that the level of Fe in Cu₂S and S in blister copper both comply with the quality requirements. Real practice has shown that the model provided useful information for determining the actual ending of copper matte converting. With growing amounts of data, the prediction accuracy of the model can be further improved.

Abstract:In a POX leaching zinc refinery in Qinghai province, reversed antimonic salt method was used for purification. For each ton of zinc produced about 70kg of zinc dust was consumed. To reduce zinc dust consumption rate, the refinery introduced B cobalt removal reagent. The B reagent comprises mostly of antimonic salts, arsenic salts, and tannin compounds, in appropriate conditions the reagent can remove cobalt consistently. With Cd concentration at 200~300mL/L in the purification feed, it was found that satisfactory results can be achieved when the reaction takes place at 83℃ for 2 hours, with B reagent dosed at 0.03kg/m³ and spent electrolyte fed at 3L/m3. Industrial applications have show that using B reagent for Co removal can reduce zinc dust consumption per ton of zinc produced by 15kg compared with the reversed antimonic salt method. It is thus concluded that in comparison with conventional cobalt removal reagents, the B Co removal reagent yields better economic outcome and at the same time produces good Co removal efficiency, hence worthy of promotion.

Abstract:Zinc sulfide concentrate is usually associated with a certain amount of thallium, and in some zinc-lead deposits, the content of Tl can be particularly high. In a conventional hydrometallurgical zinc refining process, the Tl contained in the raw material can affect the operation and product quality. The symptoms include problematic assaying, difficulty in zinc dust precipitation, and cobalt removal. As the stream and distribution of Tl across a hydrometallurgical zinc refining process is closely related to its content in the ore, the selection of auxiliary materials and operating conditions, by manipulating these factors the adverse effect of Tl can be controlled. There are three paths of bleeding Tl from a conventional hydrometallurgical zinc refining process: oxidizing precipitation during leaching, zinc dust precipitation during purification, and concentrating Tl into high F-Cl offgas dust by volatilizing thallium chloride in the rotary kiln. When the Tl grade in the feed is low and when Mg powder or oxygen is used as the oxidant for leaching, Tl can be removed mainly through sponge cadmium or cobalt residue (dependent on the lead content in the zinc dust); when the feed Tl is high and when hydrogen peroxide, or potassium permanganate or ozone is used as oxidant, Tl can be removed through high F-Cl offgas dust.

Abstract:In recent years, the development of the side-blowing furnace has constituted a great competitive pressure on the flash furnace, which urgently requires the latter to be developed from a smelting furnace with low reactor heat load and low feed capacity into a high intensity smelting equipment with reactor heat intensity above 2000MJ/m3h and the feed capacity above 230t/h. In this paper, the intensified smelting capacity of flash furnace is optimized and improved from a design perspective including the following aspects: increase the net height of reactor to meet the needs of high feeding amount; sawtooth water jacket+refractory brick structure adopted for the reactor cylinder to adapt to the intense erosion of off-gas; increase the internal width and net height of the settling tank, ensure the designed off-gas flow rate below 6m/s, and slow down the erosion of high temperature off-gas and the dust generation; adopt copper water jacket+refractory brick structure in the gas flow area of settling tank; the leeward side of uptake flue should also be provided with horizontal water jacket; the furnace roof adopts horizontal sawtooth water jacket structure with embedded refractory to prevent the refractory bricks from falling off. In addition, to ensure the safety of the furnace under the condition of high intensity smelting, the monitoring of the furnace bottom temperature and cooling water leakage shall also be considered. The optimized and improved flash furnace can satisfy the expected smelting intensity with stable, safe and reliable operation.

Abstract:As one of the main operations in aluminum electrolysis production, changing the anode will damage the material and energy balance of the electrolytic cell, reduce the current efficiency, cause bulging on the anode and even rolling aluminum accident, therefore has a great influence on the stability of the electrolytic cell. Based on the background of SY300kA electrolytic cell in an electrolytic aluminum plant, this paper analyzes two common anode-changing sequences, measures the changing trend of electrolyte temperature after anode-changing, theoretically calculates the heat loss of anode-changing and tracks the current distribution characteristics of the electrolytic cell after anode-changing. The impact of reasonable anode changing sequence on the stability of electrolytic cell and the impact of anode changing operation on the temperature field and current distribution of electrolytic cell are obtained. In addition, the improvement measures are proposed from two aspects of adjusting the site technological conditions and improving the operation quality, providing reference for anode changing operation of similar electrolytic aluminum plants.

Abstract:Continuous Cu smelting technology comprising oxygen-rich side-blowing smelting + multi-lances top converting process + pyrometallurgical anode refining” is the advanced copper smelting technology in the world. In order to reduce the loss of valuable metals in slag, oxygen-rich side blowing slag and multi-lances top converting slag are selected as objects to study the distribution of copper and iron elements in slag in different mineral phases, and the following conclusions are obtained: the copper content in smelting slag and converting slag is 1%-1.7% and 12%-15%, respectively; smelting slag is mainly composed of fayalite, magnetite, glass phase and Cu matte. The slag with high Fe-Si ratio is selected for smelting slag, and a certain proportion addition of pulverized coal can reduce the slag viscosity. The converting slag is mainly composed of calcium ferrite, magnetite and metal Cu phase. Calcium slag is selected for converting slag, and the content of SiO₂ shall be controlled below 3%. The main factors affecting Cu content in slag are slag type, furnace temperature, magnetic iron content, slag layer and matte/blister copper layer thickness.

Abstract:In this paper, the form and reason of S31608 stainless steel elbow’s failure in silicon tetrachloride cold hydrogenation process are studied. The chemical composition, microstructure and corrosion product composition of the elbow failure location are analyzed by metallographic analysis, ESD and SEM method. The results show that the main failure mode of elbow is stress corrosion cracking with the inner wall extends to the outer wall. The external cause of cracking is the combination of Cl^- ontaining corrosive medium in contact with the inner wall of the elbow, residual stress produced by fabrication and stress superposition under the action of internal pressure. The internal reason is the precipitation and deformation structure on grain boundary of elbow. The main reason for S31608 stainless steel failure is the presence of Cl^- Pand other corrosion components in the medium and stress. With a decline in corrosion resistance caused by the precipitation and deformation structure on the grain boundary of the elbow, the Cl^- contained in the corrosive medium on the elbow fracture, which poses a extremely strong penetration and erosion effect on the Austenitic stainless steel surface film, is able to dissolve the protective film and causes the failure of the elbow due to stress corrosion under the action ofresidual stress and working stress.

Abstract:The rhenium determination method stipulated in the industrial standard “Determining Rhenium in Crude Rhenium Compounds Using the Tetraphenylarsonium Chloride Hydrochloride Hydrate Method” (YS/T836—2012) is low in samples adaptability, long in process flow, and high in costs, hence not favorable for guiding production. To address this issue, a convenient rhenium assay method has been developed based on the actuality of plant operation: first dissolve the sample completely with 5mL of nitric acid, 0.8mL of saturated bromine solution and 10mL of hydrochloric acid; then analyze the sample using ICP-AES at Re227.52nm. Precision testing and spike-and-recovery experimentation indicates that the ICP-AES method produces a relative standard deviation (RSD) between 1.25% and 3.45% and a spiked recovery between 95.23% and 102.22%, which meet the assay requirements. In addition, the ICP-AES method can reduce the testing duration from 8h to 4h, meeting the process requirement for rapid testing, and all the testing reagents are conventional and readily available, hence low in testing costs. The method is thus recommended for promotion.

Abstract:The large volumes of offgas dust generated from copper pyrometallurgical processes contains arsenic and multiple valuable metals, a potential environmental hazard but important secondary resources at the same time. The approaches of recovering resources from the smelter dust are mainly: hydrometallurgical, pyrometallurgical, and combination. In the pyrometallurgical approach, impurity elements and metal values are selectively separated through oxidizing roasting (smelting) or reducing roasting (smelting). Such processes are short, capable of treating large quantities of dust, and low in capital costs, but at the same time have several disadvantages: low metal recovery, high overall energy consumption rate, large quantities of waste, and heavy environmental impact. The hydrometallurgical processes include acid leaching, alkaline leaching, and water leaching. Comparatively acid leaching is more developed, and numerous in industrial applications. However, acid leaching also generates large amounts of residue which requires treatment. The combined processes are mainly a combination of hydro and pyro metallurgical process or of mineral processing and metallurgical treatment. Such a combined approach has salient advantages when treating smelter dusts of complex composition in terms of elements and substances. These processes have good arsenic removal performance, and allow the recovery of multiple metal values including copper, zinc, cadmium, lead, bismuth, antimony, indium, but is also long in process flow and high in capital costs.

Abstract:Electronic wastes from spent electronic and electrical equipment contain large amounts of valuable metals, including copper, gold, and silver. The content of these metals in the electronic wastes, compared with their occurrence in primary ores and other primary sources, is higherand easier to extract. Recovering these metal values therefore can bring significant social and economic benefits. Pyrometallurgy, in this regard, has its own strength: supporting large throughputs, relatively simple equipment and process flow, and high adaptability to raw materials. The paper is a summary of the current practices in China and other countries of recovering metal values from electronic wastes through pyrometallurgy, including the recovery of copper, precious metals, and offgas treatment. Finally the prospects of the electronic waste recovery industry moving towards a more systematic, extensive, and efficient operation are depicted.

Abstract:Steel slag is one of the bulk sold wastes that have not been well utilized by steel mills. At present, the overall utilization rate of steel slag in China is only around 20%, much lower than in many developed countries, in which over 90% of the slag can be utilized. The amount of unused steel slag stock in China is enormous: 1 billion metric tons. After an overview of the related literature by scholars of China and other countries on steel slag utilization, the paper gives a short description of the six main processes of steel slag treatment in China, and compares their advantages and disadvantages. Then the paper reviews the recycling practices inside steel mills, including recovering valuable metals and sintering. Lastly the paper reviews the recycling practices outside steel mills, including the utilization of steel slag in construction materials making, road pavement, fertilizers, ceramic products, pollution control of sea and other water bodies. The paper concludes that for better utilization of steel slag, a more detailed classification system, upgraded milling process and equipment are needed.

Abstract:China is rich in arsenic reserves, but most of these are of paragenetic and associated minerals. In actual processing, the majority of these minerals goes into tailings and metallurgical residue/slag. As arsenic poses a great threat to environment and human health, usually some neutralization treatment is needed. With decreasing profits in the mining and metallurgical industries, neutralization is becoming less feasible economically, and turning arsenic solid wastes into useful resources is a promising trend. The paper begins with an overview of the current utilization of arsenic-bearing solid wastes in China, of related policies and arsenic materials of high added value, then describes the processes of arsenic recycling and related applications. The paper concludes that, apart from increasing environmental pressure, an increasing demand for arsenic-bearing materials, the reliance on importation of high purity arsenic, and governmental support in finance and polices altogether will usher in a promising future for the utilization of arsenic-bearing solid wastes.

Abstract:Experimental study on oolitic hematile ore smelting reduction was carried out. X-Ray diffiraction (XRD) and optical microscopy obversition (OP) were employed to identify the mineral composition and distribution. The influence of additives, reduction temperature and holding time on metallic iron recovery rate was investigated. Analysis indicated that the carbon content in iron increased exponentially with temperature, the expression was y=0.002·e^0.0064T Total ferrum, P, S content were all increased linearly with temperature. Thermodynamical and reaction kinetics analysis indicated that the solid carbon C_(s) and dissolved carbon [C] participated in [FeO] reduction reaction, the main reactant was solid carbon. The effect of [FeO] and [C] concentration variation on reduction reaction rate decreased with temperature increase. The rate contant of reduction reaction inceased with temperature.

Abstract:The smelting process of metallurgical furnace is accompanied by complex multiphase chemical reactions at high temperature, so it is difficult and costly to carry out experiments directly. Hydraulic model experiment and numerical simulation methods are widely applied by researchers to carry out the study. The side-blowing gas penetration distance and agitation conditions are the key indicators in the design of side blowing furnace and lance, which affect the design of side blowing furnace width and spray gun structure. In this paper, the impact of the lance immersion depth, lance height, bath liquid level, lance diameter and gas flow volume on the side-blowing gas penetration distance and bath agitation are studied by using hydraulic model experiment. The results show that: bath liquid level, lance height and the immersion depth of the lance have no or insignificant impact on the gas penetration distance; the side-blowing gas penetration distance is mainly related to the gas outlet velocity as the distance increases with the increase of gas flow and the decrease of lance diameter; the gas flow has a great impact on the flow and agitation of the bath in the furnace, reasonable lance structure, layout design and gas flow selection will facilitate the formation of sufficient flow field and agitation power field in the side blowing furnace.

Abstract:An extraction-stripping process was used in a hydrometallurgical refinery to recover rhenium (Re) from waste acid. However, the separation of impurities was not thorough, and the Re recovery was low. The test study explored the technical challenges in the extraction process, and compared the process test results of extracting-stripping Re with and without pre-treating waste acid. The test results indicate that: when the extractants (N235: sec-caprylic alcohol: kerosene) are mixed at a ratio of 20∶20∶60, the Re recovery reaches 88.42%; that washing the loaded organic phase with water or acid does not prevent the yielding of large amounts of Re-bearing crud during stripping with ammonium; that washing the stripping residue with hot water or acid does not produce favorable results, with low Re leaching efficiency and difficulty in separating Re and Bi; that adding the waste acid pre-treatment procedure brings about the best result in removing main impurities and concentrating rhenium; and that extracting and stripping the pre-treated Re solution can produce high quality ammonium rhenate, with extraction efficiency at 98%, and stripping efficiency at 99%.