China Nonferrous Metallurgy

Abstract:80% of CO₂ emissions in China came from coal in 2019, 14% from oil type and the rest from natural gas and other energy resources. In order to achieve the carbon neutrality goal and transform the energy development mode of China, acceleration of new energy development (wind energy, solar energy and biomass energy, etc.) is the most important way. In this context, it is an inevitable trend to implement the transformation of energy structure by non-ferrous metallurgical industry, an energy-intensive industry and the carbon reduction industry focused by the state. Based on this fact, this paper analyzes the output, energy consumption and carbon emission of China’s non-ferrous metallurgical industry, and makes an in-depth research on the energy consumption and carbon emission status of aluminum and copper industry with the maximum output. It also analyzes the development strategy goal and realization approach for energy transformation and updating of non-ferrous metal metallurgy industry and proposes related policy and suggestions.

Abstract:Two types of carbon emission reduction can be achieved by waste incineration power generation. The first is to prevent the decomposition of solid waste during the stockpiling in landfill to release greenhouse gas (its main composition is CH₄); secondly, the superheated steam produced in waste incineration boiler can be used to power the turbo-generator set, thus avoiding greenhouse gas emission caused by thermal power generation. This paper briefs on the establishment and development course of Chinas carbon trading market, based on which analysis is made on the emission reduction effect and measurement of carbon reduction of waste incineration power generation project. It points out that the waste incineration power generation project can be developed as CCER for carbon market trading, with the carbon emission reduction per ton of waste as about 0.1-0.5 tCO₂. As a significant component of renewable energy, waste incineration power generation industry should actively engage in carbon market trading, shoulder the important task of pollution and carbon reduction and facilitate the realization of the carbon peaking and carbon neutrality goals.

Abstract:The vanadium redox liquid flow battery is a kind of safe, environmentally friendly, stable and long-life electrochemical energy-storing device, which is of great significance for the implementation of green-power energy storage and the policy of carbon peaking and carbon neutrality. In this paper, the structure and features of the vanadium liquid flow battery are introduced firstly; then the vanadium battery application status and the progress of research on the electrolyte, electrode and diaphragm are reviewed in detail; the relevant state policies on vanadium resources and full vanadium battery are briefed, followed by the estimate of the current market size of vanadium liquid flow battery based on the available data. Finally, the vanadium battery technology and its industrial development status are summarized and the key research directions in the future are prospected.

Abstract:Aiming at the change rule of the jet flow field in the bath area of the oxygen coal combustion smelting-separation furnace, by means of theoretical analysis and experimental study, investigation is made of the motion mode and penetration behavior of the jet flow of the side-blown gas in the bath respectively. The ascending motion model of jet bubbles is established based on the force condition of bubbles in the jet flow. By comparing the experimental phenomena, the rule of different motion stages of jet bubbles is verified. It is shown by jet penetration phenomenon and theoretical analysis results that the injection flow is the main factor affecting the side-blowing penetration distance; when the flow is constant, the diameter of oxygen lance casts a greater impact on the penetration behavior than immersion depth of the oxygen lance; based on this, a mathematical model of the side-blowing jet penetration distance of circular tube oxygen lance is established, and it is known from this that the energy change of the side-blown jet penetration distance is mainly kinetic energy conversion, which further provides theoretical guidance for the design of oxygen lance for oxygen coal combustion smelting-separation furnace and the optimization of bath flow field.

Abstract:The oxygen-enriched intensified smelting technology is used in the Double-Flash copper smelting process, the concentration of the enriched oxygen is usually controlled between 80% and 90% in the design. After the flash furnace of Guangxi Jinchuan Company was put into production, there were a series of issues such as high fuel consumption, high temperature of off-gas system, melting and caking of boiler soot, nozzle accretion, incomplete reaction, etc., which severely limit the uplifting of production efficiency. Aiming at these issues, the Company has improved the interlock control and valve automatic on/off for the air supply system, and the air flow guide components are added to the nozzle. With this improvement, the nozzle pure oxygen (enriched oxygen concentration 100%) smelting in Outokumpu flash furnace is realized, furthermore, the smelting control is more stable, the production capacity is increased accordingly, the production load of the smelting furnace is enhanced to 270 t/h (the designed maximum load is 246 t/h) and the production load of the converting furnace is enhanced to 100 t/h (the designed maximum load is 90 t/h). After the pure oxygen smelting in flash furnace, the self-thermal production is achieved for the double-furnace, which cuts fuel consumption and reduces carbon emission, and because the air consumption is lowered, there is less nitrogen entrainment, and the emission of nitrogen oxides is reduced.

Abstract:As the main material for electrolytic refining of nickel, the nickel sulfide concentrate contains massive impurities, e.g., iron, copper, cobalt, lead, zinc. Among these, iron is one of the major impurities during the electrolytic refining of nickel. Currently, the electrolytic refining of nickel sulfide mainly involves two systems, soluble-anode electrolysis and insoluble-anode electrodeposition, which produce electrolytic nickel and electrodeposited nickel respectively. To prevent impurity precipitation at the cathode, which will affect the quality of electrolytic nickel, it is necessary to reduce the iron content in the solution. In this paper, the thermodynamics of iron removal precipitation of electrolytic refining of nickel is discussed, also discussed are four major iron removal technologies used in the hydrometallurgy production of nickel, namely, neutralization hydrolysis process, sodium jarosite process, hematite process and goethite process. In addition, the existing problems in the industrial application of iron removal technologies in the purification process of the electrolytic refining of nickel system and in the leaching process of the nickel electrodeposition system, together with the advantages and disadvantages of the four iron removal methods were analyzed. A prospect about the iron removal technology based on the magnetofluid-assisted chemical precipitation method was also provided.

Abstract:This paper introduces the method for extraction of high purity ammonium rhenate product by cyclic enrichment of rhenium in arsenic sulfide slag-leaching of copper separation solution-iron exchange process. In this process, the rhenium content can be enhanced to 1-2wt.% after enrichment treatment of sulfide slag returned to flash smelting for multiple times; the cost of rhenium leaching can be significantly lowered with rhenium-rich sulfide slag leached by copper separation solution obtained from hydrometallurgical leaching of copper anode slime, and the leaching rate of rhenium can be stably controlled above 95%; the adsorbtion/desorption rate of rhenium in iron exchange process can reach above 97%; the overall recovery rate of rhenium in ammonium rhenate crystallization process is 100%, and the purity of ammonium rhenate stably maintained at 99.99% after secondary crystallization. The whole process flow has the advantages of environmentally friendly, extremely low content of heavy metals in waste waster, very low external discharge and easy to be treated. The production practice in recent three years has proved that this process is characterized by simple process, good stability, low operation cost, little waste water drainage and high rhenium recovery efficiency and high purity in comparison with conventional high-pressure oxidative leaching-extraction process, etc.

Abstract:Antimony is a common impurity in tin metallurgy. Sn and Sb separation is one of the key difficulties encountered in tin production. In this paper, the process of NaOH leaching → antimony oxide precipitation → purification and impurity removal → cathode antimony production by electrodeposition is used to separate tin and antinomy in tin anode slime. The test results show that with the initial concentration of NaOH of 167 g/L, a liquid-solid ratio of 5〖DK〗∶1, leaching temperature of 150 ℃ and leaching time of 60 min, the tin leaching efficiency is 89.68% and the antimony leaching efficiency is 75.57%. Oxidative precipitation of antimony is conducted for the leachate, with an antimony precipitation rate of above 99%, and the produced sodium antimonate is up to the quality standard of chemical products. The liquid after antimony precipitation is added with sodium sulfide for lead removal and then electrodeposition is conducted. The quality of the cathode tin produced by electrodeposition is up to the quality standard of tin fine product. The technology can separate most of tin and antimony from the high Sb-Sn anode slime, which are recovered in the forms of tin fine product and sodium antimonate, the recovered products are of high value.

Abstract:In this paper, based on the brief introduction of component differences between Sb concentrate and Sb-Au mineral, the detailed comparison is made for the technical parameters of the two minerals in the technological process of blast furnace smelting-reverberatory furnace refining. At first, the most difference between Sb concentrate and Sb-Au mineral is the different contents of As and Au, which will bring adverse effects on the pelletizing process; secondly, during the blast furnace smelting process of the two minerals, most Sb, Pb and As will enter antimony-oxygen powder, and most Au in the Sb-Au mineral will be enriched and enter the precious Sb; finally, the two kinds of concentrate are smelted to produce antimony-oxygen powder, which is subject to reductive smelting and oxidizing refining to produce qualified antimony ingot. However, the Au in the antimony-oxygen powder produced from Sb-Au mineral will continue to be enriched and enter the antimony ingot, which will increase the difficulty of post-processing. The technological processes of antimony pyrometallurgy for Sb concentrate and Sb-Au mineral are almost the same, the differences are that the output of arsenic-alkali slag is different and the Au distribution in various products is different, the precious antimony smelted from the Sb-Au mineral is an important raw material for gold extraction.

Abstract:At present, most of electric furnace power setting has been determined by operators according to their experience and onsite operation conditions, it is greatly affected by personal experience and operation, which makes it difficult to guarantee the real-time optimality of given power as to affect the production indicators. As regards smelting furnace of RKEF ferronickel smelting process, this paper proposes an optimization method for online control of electric furnace power. By using this method the online testing is performed for the process variables related to furnace charge, off-gas and furnace cooling system by establishing the electric furnace heat balance model to achieve online calculation of optimum set value of electrode power; by building Error BP network model, the measured data of slag tapping cycle are utilized to produce data sample for training and updating the network model, which realizes prediction and online modification of calculation error of heat balance and enhances the accuracy and adaptability of heat calculation. The effectiveness of this method is verified by simulation experiment based on engineering data. This paper indicates that using this control system can solve the core issue of intelligent smelting by ferronickel furnace. In the next step, the system needs to be combined with other subsystems to form a complete solution of intelligent smelter.

Abstract:Fuel consumption is an important factor affecting energy conservation and emission reduction of OBASKs. To promote the energy efficiency of OBASK and reduce carbon emission, targeting at the fuel type, this paper replaced the original blast furnace gas with calcium carbide gas of higher calorific value and analyzed the numerical differences in the energy efficiency of OBASK, fuel cost, and CO₂ emission based on METSIM. The results indicate that when the calcium carbide gas is adopted to replace blast furnace gas, there is an increase of 4.77% in energy efficiency of OBASK, a sharp decrease (only 30% of the original) in fuel consumption, and a decrease of 325.01 kg in CO₂ emission for per ton of lime production. Therefore, calcium carbide gas is recommended as the fuel of OBASKs to boost economic interest and environmental benefits in addition to realizing effective utilization of industrial by-products.

Abstract:Based on the fact that the solubility product of manganese sulfide, ferrous sulfide and thallium (Ⅰ) sulfide exceeds that of arsenic sulfide, this paper aimed to improve the existing high-pressure closed digestion-ICP-MS method to make part of the metal ions brought by the impurities fully digest into the solution, so as to improve the accuracy and precision of determination of Mn, Fe and Tl in sulfide residue. It is found after optimization that the optimal digestion condition exists in a mixed acid system of hydrochloric acid + nitric acid + hydrofluoric acid + perchloric acid (with a volume ratio of 15∶5∶5∶3) at a particle size of 250 meshes. The measured value of Mn, Fe and Tl are respectively 0.025 70 g/kg, 0.024 10 g/kg and 0.000 50 g/kg in sulfide residue after arsenic removal. The improved method was used to determine the national standard substance of Mn and Fe ore and standard substance for composition analysis of sulfide single mineral. The internal standard elements of 89Y and 192Ir and isotopes of ⁵⁵Mn, ⁵⁶Fe and ²⁰⁵Tl were used to eliminate interference. The determination results showed the same results as those measured with national standard method, which indicated high accuracy and precision of improved method. Besides, it can be inferred from the determination results that the hydrogen sulfide was excessive in waste acid sulfidization plant, which provided a certain reference for adjusting the addition of hydrogen sulfide in the subsequent stage.

Abstract:Ferroniobium was prepared through aluminothermal reduction smelting with niobium concentrate as the raw material, and impurity elements in ferroniobium, including silicon, phosphorus and titanium, were determined simultaneously with samples for alkali fusion through ICP-AES. Moreover, the selection of instrument parameters and spectral lines of the determined elements was discussed. The determination results were compared with those obtained by wet-chemical method under the selected determination conditions. The elements in samples were determined repeatedly. The detection limit, accuracy and standard recovery rate of this method were examined. In addition, the relative standard deviation of this method was less than 2%, and the recovery rate was 98%-100%. Appropriate sample pretreatment methods and instrumental analysis conditions are adopted for this method, realizing the efficient, rapid and accurate determination of silicon, phosphorus and titanium in ferroniobium.

Abstract:As a by-product from copper smelting, copper slag is a kind of important secondary mineral resources. The copper slag contains Fe, Cu and a small amount of Zn, Co, Ni and other valuable metallic elements. Analysis is made for the occurrence and forms of the major valuable elements in the copper slag, and the current research status of the recycling technologies for major elements is reviewed. The analysis shows that the Fe element in copper slag is recycled mainly by the preliminary processing of the two forms of oxidizing-roasting enrichment of Fe3O4 or reducing-roasting enrichment of iron metal, and by magnetic separation or smelting-separation and other technologies; the mineral processing method and electric furnace cleaning method are the major routes to recycle Cu element in copper smelting slag; the use of rotary kiln or rotary hearth furnace process can realize the collaborative recycling of Fe and Zn in the copper slag. By using the hydrometallurgical leaching process, the Fe, Cu and Zn elements in the copper slag can be recovered in steps or collaboratively, but this technology has long process flow and a certain environmental pollution. A prospect about the potential technologies or methods for recycling valuable elements in copper slag is made and it is pointed out that utilizing the waste heat of molten copper slag to develop new high-temperature modifiers and new reducing agents (biomass carbon-containing reducing agent, secondary metal siliceous thermal reducing agent, etc.) presents a new direction for the study on the recycling technology of valuable elements in copper slag, which can realize energy-saving and consumption reduction in copper slag recycling as well as the collaborative recycling of other secondary resources.

Abstract:The Concentrator of Guangxi Jinchuan Nonferrous Metals Co., Ltd. produces over 1.1 million tons/a of tailings from reprocessing flash smelting slag, with a low content of active substances of Al₂O₃ CaO and MgO. As inactive material, they can only be used as iron regulator with low value and single purpose. In this paper, the physical excitation and excitant excitation are used to modify the tailings from reprocessing of flash smelting slag of Guangxi Jinchuan Nonferrous Metals Co., Ltd. The maximum addition volume of taillings as cement admixture is explored through test to reach the following conclusion. The tailings fineness is changed through mechanical pulverization to make the specific surface area of tailings reach above 404 m2/kg, which can meet the requirement of Grade 75 active material stipulated by GB 12958—1999; without adding any additives, the maximum addition ratio of tailings from reprocessing of flash smelting slag as 20% meets the requirement of Grade 75 active material stipulated by GB 12958—1999; a comparison experiment was made by adding lime and gypsum residue. It proves that the excitation effect of gypsum residue is less significant than that of lime. While adding 5% lime with total addition ratio of 30%, the requirement of Grade 75 active material stipulated by GB 12958—1999 can be basically met; the test is conducted by using slag powder and steel slag powder with the total addition ratio as 50%, and the effect of slag powder is obvious. With the tailings addition ratio as 30%, it can meet the requirement of Grade 75 active material stipulated by GB 12958—1999.

Abstract:The lime-iron salt process is usually used in the treatment of arsenic-bearing acidic wastewater, and it has the advantages of fewer kinds of reagent to be added, high precipitation efficiency, stable and qualified discharge of wastewater, low running cost, easy operation, etc. In this paper, the reaction mechanism and influence factors of this process are elaborated and summary is made for this process. When the pH value of the reaction liquid is set as 7-8, the oxidizing reaction of Fe²⁺ is high with the best arsenic removal effect; the molar ratio of Fe/As of the reaction liquid is generally 5-10, which is conducive to iron arsenate formation and accelerates flocculation; the partial sediment returning method adopted can play a role of crystal nucleus for the reaction process; in this way, not only the precipitation velocity of the neutralized residue can be raised, but also the reagents can be saved with the volume of neutralized residue reduced. The engineering practice shows that this process can efficiently treat the arsenic-bearing acidic wastewater from copper smelter, the efficiency for removing Cu, Pb, Zn and As can be stably up to 99% or more. In addition, the As in the neutralized residue is in form of pentavalent arsenate and the concentration of toxic leaching is less than 5 mg/L, which can be safely stored in residue pond.

Abstract:Through the statistics of thallium content in zinc-bearing slag, off-gas washing acid and intermediate products of a zinc hydrometallurgy plant, the flow distribution of thallium in the technical process of zinc hydrometallurgy is analyzed and studied to find out the main existing forms of thallium enrichment and bring forward major measures for effectively preventing thallium loss and pollution. Meanwhile, the emphasis is laid on the analysis of the three-stage combined treatment method for thallium-containing wastewater in the zinc hydrometallurgy industry, namely oxidative neutralization and sulfidization, treatment with biological agents, and ion exchange. Compared with ordinary treatment technologies, using this combined treatment method can save 100 kg/d of sodium sulfide and reduce 1.56 kWh/t of energy consumption of wastewater while lessening 2.23 yuan/t of direct cost for wastewater treatment. Moreover, the thallium content in the treated water can fully meet the requirements of the modification list in Emission Standard of Pollutants for Lead and Zinc Industry (GB 25466—2010) to be implemented in 2022.

Abstract:In China, the zinc hydrometallurgical plants usually reuse the cell zinc anode slime and plate zinc anode slime directly in the leaching system, however, during this process, it is hard to control the Mn²⁺ concentration in zinc electrolyte. In this paper, it is creatively put forward that when the Mn²⁺ concentration in zinc electrolyte is less than 4 g/L and the plate zinc anode slime is proportioned with zinc concentrate, the MnO₂ is reduced under high temperature to low valent Mn by roasting, so as to lower the oxidation efficiency of the anode slime to increase the concentration of Mn²⁺ in the zinc electrolyte. Parameters for operation are follows: mass proportioning ratio of anode slime and zinc concentrate about 1∶100, temperature of fluidized bed 910-950 ℃, hearth temperature 300-330 ℃. When the Mn²⁺ concentration of zinc electrolyte is not less than 4 g/L, the plate zinc anode slime is subject to ball mill grinding and slurrying before being returned to the leaching system with the particle size being controlled around 0.074 mm, the oxidation efficiency can be more than 91%. The reuse modes are taken under different conditions, which can not only achieve the comprehensive recycling of valuable metals, but also be conducive to the timely adjustment of the Mn²⁺ concentration in the zinc electrolyte to lay a solid foundation for the stable running of production.

Abstract:The high-acid and high-chlorine wastewater is a major discharged wastewater from the joint mineral processing and metallurgical treatment of copper anode slime and the high acidity, high chlorine content, more impurities and other features result in the low resource recycling and high treatment cost. Through the analysis on the principle and the production practice of wet selenium removal from anode slime, the feasibility of returning the high-acid and high-chlorine wastewater to the wet selenium removal process for resource utilization is explored. The results show that when the concentration of the selenium removal slurry is 1.70-1.80 kg/L the high-chlorine and high-acid wastewater amount is 763 L per tank, the industrial salt consumption is 50 kg per tank and the sulfuric acid consumption is 100 L per kettle, the technical indicators can be achieved that the selenium removed residue contains 2.82% of selenium, the tailing ores contain 50 g/t of gold, the tailing ores contain 0.25% of silver, the concentrate grade is 54.04%, the high acid wastewater contains 7.34 g/L of copper, and the wastewater from mineral processing contains 0.57 g/L of copper. The production indicators are relatively stable and both the discharge of the liquid after selenium reduction and the sulfuric acid consumption are lowered.

Abstract:In order to improve the electrochemical properties of LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials, such cathode materials were coated with graphene oxide, and the effects of the amount of graphene oxide coating on the structural morphology and electrochemical properties of LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials were studied through thermogravimetric analysis, SEM analysis, initial material charge-discharge curve, cycle property curve and rate property curve. The results showed that when the additive amount of graphene oxide was 8%, under the voltage platform of 2.75-4.3 V at the rate of 0.2C, the initial discharge capacity reached 165.37 mAh/g and the capacity retention ratio reached 96.50% after 30 cycles, while the capacity retention ratios at the rates of 0.5C and 1C were 95.2% and 92.89% respectively after 30 cycles. In addition, these materials have great cycle property and favorable rate property under different current densities.