China Nonferrous Metallurgy

Abstract:In this paper, the origin and development of nickel-cobalt precipitation and enrichment technology in high-pressure acid leaching (HPAL) process for low-grade laterite nickel ore are introduced. The problems existing in the current application process are described in detail. At the same time, the alkali activation controlling technology (AACP) invented by ENFI is emphatically introduced.The technology includes three core technologies,in-situ base conversion of sodium hydroxide, pre-seeding reforming and template-induced growth, and convergent system regulation. It avoids the technical barriers set by foreign companies through patents in hydrogen sulfide and magnesium oxide precipitation technologies. The technical process is ingenious, the equipment is simple and universal, and the compatibility with the high-pressure leaching system is strong. The quality of nickel-cobalt hydroxide (MHP) products is excellent and stable.Moreover, ENFI has developed a high-pressure acid leaching process equipment engineering system (ENFIHPAL) for the problems existing in HPAL, which shortens the project implementation cycle, and carries out basic selection design, optimization and problem discrimination for the whole equipment system, which can ensure the stability and operation rate of the equipment system under complex operating conditions.After the successful application of AACP technology in Ruimu nickel-cobalt project in Papua New Guinea, it has also achieved remarkable application results in Liqin project, Huayueproject and other projects in Indonesia. The MHP products have become the best quality intermediate products at the raw material supply of the EV power battery industry.The HPAL-AACP process route is expected to be the first choice for the efficient utilization of low-grade laterite nickel ore.

Abstract:The platinum group metals distribution is highly concentrated around the world, while platinum group metal resources are significantly limited in China. It is important to achieve efficient utilization of platinum group metal resources during the overseas development of platinum group metal mines by Chinese companies. In this article, the current pyrometallurgy mechanism and process of platinum group metals are reviewed, with a view to provide reference for future research on pyrometallurgy technology of platinum group metal ores. For platinum group metal concentrate from flotation, the electric furnace+converter process is still the main pyrometallurgy method, including drying, smelting to prepare low nickel matte (furnace matte) by electric furnace, converting to prepare high nickel matte (converter matte) by converter, etc. Future research on platinum group metal ores smelting technology should focus on the development and utilization of efficient smelting methods such as enhanced smelting and bath smelting, of Platinum Palladium minerals, and low grade nickel matte converting can focus on the feasibility of continuous converting such as bottom blowing and multi lance top blowing instead of PS converter converting.

Abstract:A large amount of dust is produced in the process of copper smelting, and about 10%~50% of the associated arsenic in the concentrate enters it. At the same time, the dust also contains valuable elements such as Cu, Zn, Pb, Bi, Au and Ag, which need to be recovered and harmlessly treated.The hydrometallurgy process for arsenic-containing dust treatment has the advantages of high metal recovery rate, good separation effect of valuable elements and low investment cost. However, there are some disadvantages, such as long process flow and separate treatment of leaching residue.The pyrometallurgy process has the advantages of short process flow and large processing capacity. The arsenic products are mostly arsenic oxides or elemental arsenic with high purity, which is convenient for further purification and resource application of arsenic. However, there are some disadvantages such as high energy consumption and reprocessing of products.The combined process of hydrometallurgy and pyrometallurgy to treat arsenic-containing dust has obvious advantages in metal recovery rate and product quality. Arsenic can be curing and stabilized , and As2O3 or arsenic products can be produced. At the same time, valuable metals such as lead, zinc, copper and bismuth in dust can be comprehensively recovered, which is the current mainstream direction.The treatment methods of arsenic-containing materials are mainly harmless disposal and resource utilization. Exploring the new arsenic productcan bring good benefits to society, environment and economy. In the future, thein-situ collaborative treatment of arsenic-containing materials and the production of arsenic are important directions for future development.

Abstract:At present, alumina is widely used to absorb hydrogen fluoride escaping during the aluminum electrolysis process, but the adsorption mechanism and process are not clear. This paper introduces the current research status of the adsorption process of hydrogen fluoride on alumina and the structure of the adsorption products. The research methods adopted by the researchers include two types. One is the experimental methods, including measuring the volume and pressure of hydrogen fluoride before and after the adsorption, drawing adsorption isotherms, analyzing the thermal stability of the adsorption products, and studying Nuclear Magnetic Resonance(NMR) and Infrared Radiation(IR) of the adsorption products to obtain the adsorption structure indirectly. The other is to simulate the adsorption structure by computer based on density functional theory. There are two different models of hydrogen fluoride adsorption on alumina suggested by the researchers. One is Lamb model in which F atom is directly adsorbed on Al atom of alumina. The other is a bimolecular layer model in which F atoms are adsorbed on hydroxyl or water molecules on the surface of alumina. The simulated adsorption structure is also based on these two models with focusing on the adsorption sites of hydrogen fluoride on alumina surface and the formation process of Al—F bond and O—H…F bond. Finally, the similarities and differences between the two adsorption models are summarized, and the future research direction of the adsorption process and structure of adsorbed products is prospected.

Abstract:In order to meet the major demand of high-quality molybdenum raw materials in advanced Mo-materials, the production process and key factors of the preparation of multi-sequence non-agglomerated ammonium dimolybdate were proposed in this paper. Through experiments and structure characterization, the influence and control trend of various parameters in the crystallization process were discussed in details. As results, the regulation of the initial Mo concentration of the solution and the addition of the dispersant are beneficial to the stability of the supersaturation of the solution in the metastable zone of non-spontaneous nucleation, avoiding agglomeration and producing non-agglomerated ammonium dimolybdate with large particle size and narrow particle size distribution. The length of the crystal growth period determines the particle size and size distribution of the crystal, and the larger stirring speed promotes the growth of crystal. A series of non-agglomerated ammonium dimolybdate products with uniform morphology and narrow particle size distribution have been successfully developed in the industry. The particle sizeD50 are 80~130μm, 100~140μm, 140~180μm, 220~280μm, 280~380μm, respectively. It can effectively meet the strategic demand for ammonium dimolybdate products of different specifications at home and abroad. This technical achievement fills the domestic gap and leads the sales volume, that is laying a good foundation for the production and development of high-end molybdenum materials in China.

Abstract:P204 and P507 are commonly used as extractants for the extraction of rare earth leaching solution. It is difficult to effectively separate and enrich rare earths by single extractant.In this paper, the characteristics of weak extraction ability of P507 and strong extraction ability of P204 for light rare earth were used in the extraction of high concentration rare earth solution.P507 and TBP were innovatively used to extract medium and heavy rare earths, and then P204 and TBP were used to extract light rare earths. The extraction and back extraction experiments were carried out,and the following conclusions are drawn.Under the conditions of the test raw materials, the two-stage extraction process was adopted. When the phase ratio A/O=10/1, pH 4.0, room temperature, P507 volume fraction 35%, TBP volume fraction 5%, the extraction rate of P507 for medium and heavy rare earths is better, which can reach more than 90%. The extraction rate of light rare earth by P204 reached 97% under the conditions of P204 volume fraction of 35%, TBP volume fraction of 5%, phase ratio A/O=15/1, room temperature and extraction time of 5 min. Under appropriate acidic conditions, P507 loaded organic phase after two countercurrent stripping, P204 loaded organic phase after three countercurrent stripping can get high concentration of rare earth enrichment solution, and the concentration value can meet the requirements of direct entry into the extraction separation line. This study provides a reference for the recovery and separation of high concentration rare earth.

Abstract:HCl leaching-SO2 reduction is a new process for the production of tellurium. Because of the short process, the simple equipment configuration, the high recovery rate, it has a good application prospect. In this paper, the effects of leaching temperature, leaching time, leaching liquid-solid ratio, pre-reduction time, reduction time, reduction temperature and other parameters on tellurium recovery rate were investigated. In order to improve the tellurium reduction rate and recovery rate, the measures of deep reduction of by iron powder were innovatively proposed. The main conclusions are as follows, under the conditions of leaching temperature 65℃, leaching time 60min, leaching liquid-solid ratio 3∶1, pre-reduction time 5min, reduction time 6h and reduction temperature 70℃, the leaching rate of tellurium is 95.5%, and the reduction rate is 91.5%. After washing and casting, the tellurium powder can be obtained to meet the Te9995 standard. The reduction rate of tellurium can be further increased to 96% by deep reduction of tellurium-containing solution with iron powder, and the recovery rate of tellurium in the process is 91.68%. Compared with the electrowinning process, the new process can shorten the production cycle by 95%, and realize the efficient output of tellurium products and the improvement of economic benefits.

Abstract:In the process of zinc hydrometallurgy, iron powder replacement method is often used to remove copper and arsenic from acid solution containing copper arsenic.However, this method requiresn n_Cu∶n_As≥3∶1 in the solution to ensure the complete settlement of As. In the normal zinc hydrometallurgy,n_Cu∶n_As≥3∶1 in acidic solution containing copper and arsenic, the As deposition is not complete, and it is easy to produce toxic and harmful gases of hydrogen arsenide. A smelting enterprise produces copper residuum as by-product, containing 55%~60% copper, in the zinc smelting process. A method of adding copper residuum in the iron powder replacement process was proposed and verified by experiments. The results show that when the excess coefficient of iron powder is 1.5 times, without adding copper residuum, the removal rate of copper and arsenic is only 57.14% and 26.73% resp. The removal rate of copper and arsenic can reach 92.35% and 89.85% by adding 2g/L copper residuum. Under the conditions of better process parameters, reaction time 1h, temperature 80℃, copper residuum addition 2g/L, iron powder excess coefficient 1.5 times, the removal rate of copper and arsenic can reach more than 90%. This method can reduce the consumption of iron powder and reduce the production cost, which provides a reference for zinc smelting enterprises to deal with acidic solution containing copper and arsenic.

Abstract:An enterprise used ammonium chloroplatinate as raw material to refine platinum by hydrazine hydrate reduction-chlorination leaching of crude platinum-platinum precipitation with ammonium chloride. Under the original leaching parameters, the leaching rate of platinum was less than 70%, resulting in low direct yield of platinum. In this paper, the effects of reaction temperature, sodium chlorate dosage and hydrochloric acid concentration on the leaching rate of platinum were investigated. The production practice was carried out and the following conclusions were obtained. Under the experimental conditions of reaction temperature 90℃, sodium chlorate dosage 22% of the weight of crude platinum powder, hydrochloric acid concentration 3.0mol/L, stirring speed 450r/min, liquid-solid ratio 6∶1 and reaction time 4h, the leaching rate of platinum can reach 92.5% by adding sodium chlorate slowly. The production practice shows that the leaching effect is good and stable under the experimental conditions. The platinum leaching rate is maintained at about 92%, which is much higher than the platinum leaching rate of 70% under the original process conditions. The process optimization effect is good. The reaction kettle tank and stirring device used in the process are all titanium materials. The waste gas and wastewater produced enter the gold refining waste gas and wastewater treatment system, and are discharged after reaching the standard.

Abstract:Aiming at the unreasonable distribution of electric heating field caused by the deformation of anode after consumption and the excessive current density at the bottom of cathode rod in rare earth electrolytic cell, taking an 8kA rare earth electrolytic cell of an enterprise as the research object, the three-dimensional electric heating field simulation was carried out by using COMSOL multi-physical field coupling software to optimize the model of anode inclination and cathode structure simultaneously. The electric field distribution of electrolytic cell was obtained and analyzed. The results show that the current density at the bottom of the cathode rod decreases and the electric field distribution in the bottom half of the electrolytic cell is more uniform after the cathode is optimized into a hemispherical shape, which improves the local overheating of the electrolytic cell. When the anode dip Angle increases, the voltage in the tank decreases, and the high temperature area shifts to the bottom of the tank. The distribution of electric heating field is the most reasonable when the anode half-dip Angle and insertion depth are 8° and 320mm.

Abstract:There are significant limitations in the control of the arc flow parameters of the AC electric arc furnace in the domestic metallurgical industry. Most of them are based on experience to set the working points of reactor, transformer and arc flow parameters, and lack of intelligent control of arc flow parameters for the whole process. In order to solve the problem of arc flow parameter control in the whole process of beryllium-copper alloy smelting, this paper establishes a multi-objective optimization model of the electric arc furnace smelting process from the energy perspective, and introduces Dynamic Event-triggered Mechanisms (DETMs) to optimize the model in the whole process of arc flow control, under the constraints of electrical characteristics and process indexes, the model is optimized by introducing Dynamic Event-triggered Mechanism (DETMs) to develop a smelting control strategy with synergistic effects of arc flow, arc pressure and reactance under the constraints of electrical characteristics and process specifications. The experimental results show that:① the multi-objective optimization model from the energy transfer perspective is consistent with the characteristics of the beryllium-copper alloy smelting process, and the temperature constraint is easy to observe and responds to the dynamic changes of the arc resistance to a certain extent; ② the introduction of DETMs solves the interface problem between multiple local arc flow change stages of the model, and improves the problem of lagging target value changes leading to longer smelting time; ③ the FCPs trigger arc flow target value is better than the artificial \\ timing trigger mechanism, composed of arc flow control system with strong tracking ability and robust performance, to achieve the arc flow target value ahead of the change, the local steady-state phase time consumption is shortened.

Abstract:Guangxi is an important production base of electrolytic manganese dioxide and titanium dioxide in China. The treatment of electrolytic manganese slag and titanium alum slag has always been a difficult problem restricting the development of the two industries.Since the ferrous sulfate of titanium alum slag can be used as a reducing agent to leach MnO2 from electrolytic manganese slag, the manganese leaching test of electrolytic manganese slag in sulfuric acid system was carried out in this study. The effects of the ratio of electrolytic manganese slag to titanium alum slag, leaching temperature, sulfuric acid concentration, leaching time and solid-liquid ratio on the leaching rate of manganese were investigated, and the leaching reaction kinetics was analyzed. The results showed that under the conditions of mass ratio of electrolytic manganese slag to green alum slag 10∶1.0, leaching temperature 50℃, sulfuric acid concentration 1.0mol/L, leaching time 1.0h and solid-liquid ratio 1∶15g/m, the leaching rate of manganese reached 98.67%. The apparent activation energy of the reaction was 40.49kJ/mol, which indicated that the leaching was controlled by internal diffusion-interfacial reaction. The macroscopic kinetic equation of manganese leaching process was also determined according to the linear fitting results. This study provides a reference for the recovery of manganese from electrolytic manganese slag and the resource utilization of electrolytic manganese slag and titanium alum slag, and has practical significance for the reduction and disposal of solid waste.

Abstract:The acidpickling liquid produced by the smelter is mostly treated by lime neutralization method, resulting in a large amount of calcium chloride waste liquid. At present, the treatment process is complex, the cost is high, and the economy of calcium chloride recovery is not high.In this paper, the method of direct electrolysis of calcium chloride wastewater was proposed by referring to the treatment method of chlor-alkali industry, and the diaphragm electrolysis test was carried out with calcium chloride as raw material.The effects of current density, temperature and time on current efficiency and power consumption were investigated, andthe current efficiency was comparedbetween withandwithout carbon dioxideintheelectrolytic cell.The experimental results show thatafter the cathode is introduced with carbon dioxide,slightly soluble Ca(OH)₂ can be carbonized into insoluble CaCO₃, higher current efficiencywasobtainedcompared to direct preparation of calcium hydroxide by cationic membrane electrolysis. At a current density of 40mA·cm^-2, a temperature of 50℃ and an electrolysis time of 3h, the power consumption is lower, the current efficiency is higher and the economic efficiency is best.The median particle size of CaCO₃ produced by carbonization of calcium hydroxide is in the range of 16~23μm, and the particle size is more uniform.The method of cation membrane electrolysis-carbonization to prepare CaCO₃ has high current efficiency and high product purity, which provides a new idea for the treatment of calcium chloride waste liquid produced by steel acidpickling waste liquid by neutralization method.

Abstract:To explore the problem of large-scale and harmless disposal of the redmudandmineral mud, the study of in-situ ecological reclamation of alkali-control red mud and dewatered ore mud soiled mine pits was carried out by using the synergism of sludge and five kinds of plants cooperation.The findings demonstrated that the sludge and five kinds of plants cooperation could significantly lower the salt alkalinity of the red mud andmineral mud matrix and improve nutrients, enzyme activity, and microbial diversity of the red mudandmineral mud red mineral mud matrix used for soil chemical disposal. Among these, the pH and total salt levels were decreased to 8.50 and 1.50g·kg^-1, respectively, meeting the technical specifications for mine ecological environmental protection and restoration management. In accordance with the second national soil census criteria, the levels of organic matter, total nitrogen, and total phosphorus in plants‘ first growth season met the tertiary criterion. After sludge application, the greatest alkaline phosphatase and urease activity in the redmudand mineral mud matrix were 0.17mg·g-12h^-1 and 2.05mg·g^-124h^-1, respectively. It offered a fresh concept for soil formation and large-scale ecological treatment of redmudandmineral mud.

Abstract:Blast furnace ironmaking process has some problems, such as long process, high energy consumption and strong dependence on metallurgical coke. It is of great significance to develop green and low-carbon non-blast furnace ironmaking process. The current study investigated the flash reduction behavior of fine iron ore in methane atmosphere at 1450-1550K. The effects of reduction temperature and methane concentration on the metallization rate were investigated, and the microstructure of the reduction products was observed to analyze the mechanism of flash reduction. The results showed that the metallization rate reached 90.0% when the reduction temperature was 1550K, CH4 concentration was 7.5% and the reduction time was 5.49s. The increase of reduction temperature and reduction time increased the metallization rate of fine iron ore. The solid carbon generated from the pyrolysis of methane was attached to the surface of particles, which was deposited on the surface of the reduction product, promoting the reduction of iron oxides and carburizing of metal iron. The carburization process decreased the melting point of metal iron, making the reduction product from irregular shape to spherical shape. Cross-sectional morphology was the structure of a dense iron layer wrapping the unreacted iron oxide. The reduction of FeO at the FeO/Fe interface was mainly accomplished by [C] in Fe.

Abstract:ZnO-FeO-SiO₂-CaO-Al₂O₃ is an important slag system in the lead and zinc pyrometallurgy process, and the study of the viscosity of ZnO-FeO-SiO₂-CaO-Al₂O₃ slag system with high zinc oxide content could provide theoretical support for the design of lead and zinc oxide slag. The viscosity of ZnO-FeO-SiO₂-CaO-Al₂O₃ slag system with different compositions was measured by the rotating cylinder method involving a spindle. The structure of high temperature quenched slag was determined by Fourier infrared spectrometer, and the apparent activation energy of different slags was calculated. The results show that the initial increase of ZnO content (16%~32%) could reduce the viscosity of ZnO-FeO-SiO₂-CaO-Al₂O₃ and further increase of ZnO content would greatly increase the viscosity. When the content of ZnO was 36% and experimental temperature was higher than 1623K, the increase of Fe/SiO2 and CaO/SiO₂ could reduce the slag viscosity, however, the increase of Fe/SiO₂ and CaO/SiO₂ would significantly increase the slag viscosity as the decrease of experimental temperature.

Abstract:The blank-roasting process of vanadium slag is a new method in the field of vanadium extraction from vanadium slag. It is of great significance to clarify phase variation characteristics to construct and improve the phase evolution mechanism of vanadium slag in roasting process. In this paper, starting from the phase content, morphology and occurrence of vanadium element that were easily neglected in previous phase study of vanadium slag, the variation characteristics of main phase in blank-roasting stage of vanadium slag were analyzed by equipments of mineral analyzer, XRD and SEM. The results showed that: vanadium spinel, fayalite and hedenbergite were gradually oxidized and decomposed with the increase of temperature, as well as a gradual reduction of their content. The content of manganese vanadate, iron oxide, pseudobrookite and other products increased gradually when the temperature rised. With the increase of temperature, vanadium slag, fayalite and hedenbergite were gradually transited from edge oxidation to internal oxidation until they were decomposed completely. And the oxidation and decomposition products of vanadium spinel were manganese vanadate, iron oxide and pseudobrookite, the oxidation and decomposition products of fayalite and hedenbergite were iron oxide and vitric. The vanadium element in vanadium slag mainly migrated from vanadium spinel to manganese vanadate, iron oxide and pseudobrookite. And the appropriate temperature for blank-roasting of vanadium slag was 900℃.

Abstract:The accumulation of red mud occupies a large amount of land resources, and there are environmental and safety risks. At present, recovering valuable elements from red mud is one of the effective ways to consume red mud. In this paper, high-iron red mud was treated by melting reduction method. After recovering iron, the phase analysis and micro-morphology analysis slag were carried out on the tailings in slow cooling process. The phase change of the iron removal tailings during the slow cooling process was studied. It provides a theoretical basis for preparation of cementation withiron removal tailing from high iron red mud smelting reductions. The results show that heat preservation at 1000℃ in the slow cooling process,the iron removal tailings,which is formed in the reduction condition of alkalinity 0.8, carbon ratio 1.1 and CaF₂ addition 10%, can better form the phase required for the preparation of cement.

Abstract:Lead and zinc smelting is prone to producing high acid, high halogen, and high thallium contaminated acids. Conventional treatment methods require a large amount of lime and sodium sulfide, resulting in a large amount of hazardous waste that is difficult to treat in the future. This article proposes the process of “oxidation-resin adsorption-segmented neutralization” to treat high thallium contaminated acids, and based on this method, the effects of different oxidants and adsorption forms on resin adsorption of thallium were investigated. Industrial validation was conducted, and the following conclusions were obtained: during the oxidation stage, potassium permanganate had the best effect, considering the cost, hydrogen peroxide was used for industrial production oxidation; dynamic adsorption is superior to static adsorption, and the continuous nature of dynamic adsorption in treating wastewater is beneficial for industrial applications; the anion exchange resin used in the experiment has a good adsorption effect on trivalent thallium, with a dynamic average adsorption efficiency of 89.07%. It has an adsorption effect on cadmium, with a dynamic average adsorption efficiency of 50.66%. It does not have adsorption properties on lead, zinc, and arsenic elements; the content of thallium and arsenic in the treated wastewater can reach stably. The discharge standards of 5μg/L and 0.3mg/L indicate that the thallium-content in the gypsum slag and neutralization slag produced by segmented neutralization is less than 20g/t, and they are not classified as sludge containing thallium. This method not only enriches thallium elements, but also improves the quality of gypsum slag, which is conducive to the utilization of gypsum slag resources and the reduction of thallium containing sludge. In addition, the resin can be regenerated and recycled, saving the cost of acid treatment. It has the promotion value in the field of high- halogen acid wastewater treatment in the lead zinc industry.