Recovery of valuable metals from spent lithium ion batteries by smelting reduction process based on FeO–SiO2–Al2O3 slag system

A novel smelting reduction process based on FeO–SiO₂–Al₂O₃ slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0:1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO–SiO₂–Al₂O₃ slag system for the smelting process is appropriate under the conditions of m(FeO):m(SiO₂)=0.58:1–1.03:1, and 17.19%–21.52% Al₂O₃ content. The obtained alloy was mainly composed of Fe–Co–Cu–Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.     

Thermodynamic Consideration for Oxygen Pressure in a Copper Flash Smelting Furnace at Toyo Smelter

JOM - Based on the emf measurements of the galvanic cell (Fe, MgO/O in slag or matte) and the equilibrium calculations, the oxygen pressure in a copper flash smelting furnace at Toyo smelter is...     

氧气底吹铜熔池熔炼过程的机理及产物的微观分析

对氧气底吹熔炼过程气体喷吹行为、造锍熔炼化学反应机理及熔炼炉内热工作状态进行理论分析及水模型实验和取样分析验证。结果表明,氧气底吹气流能使熔体形成均匀的扩散区,实现熔体的搅拌,在气体连续相区和液体连续相区,气液、液液之间的相互作用强烈,为炉内化学反应及传热传质提供了良好的动力学条件;氧气底吹熔炼过程在零配煤的情况下能达到自热熔炼,在节能减排方面,该工艺具有很强的优势;获得了铜渣、冰铜和蘑菇头中各组分的形貌,确定了铜渣、冰铜和蘑菇头的物相组成,渣样主要由冰铜相、磁铁矿相、铁橄榄石相和玻璃体相组成,熔炼内的氧势和硫势分布有利于反应的进行,能有效抑制Fe3O4的形成以及降低渣含铜。     

Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO₂-Al₂O₃-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.     

Magnetite in the Hurley Copper Smelter

Three aspects of magnetite smelting are discussed. The first is the working out of equilibrium conditions for eliminating sulfur. The second is the influence of magnetite solubility on the difficulty of tapping the reverb matte. The third is an approximation of the equilibrium conditions in the reverb gases which govern whether magnetite is made or reduced in the reverb slag by these gases and by any iron sulfide in the slag.     

Effect of Fe/SiO2 and CaO/SiO2 mass ratios on metal recovery rate and metal content in slag in oxygen-enriched direct smelting of jamesonite concentrate

The oxygen-enriched direct smelting of jamesonite concentrate was carried out at 1250 °C by changing the slag composition. The effects of Fe/SiO₂ and CaO/SiO₂ mass ratios on the metal recovery rate as well as metal content in slag were investigated. Experimental results indicated that the metal (Pb+Sb) recovery rate was up to 88.30%, and metal (Pb+Sb) content in slag was below 1 wt.% under the condition of slag composition of 21−22 wt.% Fe, 19−20 wt.% SiO₂ and 17−18 wt.% CaO with Fe/SiO₂ mass ratio of 1.1:1 and CaO/SiO₂ mass ratio of 0.9:1. The microanalysis of the alloy and slag demonstrated that the main phases in the alloy contained metallic Pb, metallic Sb and a small amount of Cu₂Sb and FeSb₂ intermetallic compounds. The slag was mainly composed of kirschsteinite and fayalite. Zinc in the raw material was mainly oxidized into the slag phase in the form of zinc oxide.     

基于数值模拟的闪速连续炼铜炉型结构研究

分析4种闪速连续炼铜炉型的本质特性,提出将闪速连续炼铜过程视为由相对独立的闪速造锍熔炼过程和连续吹炼造铜过程构成,分别建立闪速造锍熔炼多相平衡数学模型和连续吹炼造铜局域平衡数学模型,并通过中间物料的传递将两模型有机结合,从而构建完整的闪速连续炼铜过程热力学模型。运用此模型,考察炉型结构对闪速连续炼铜过程的粗铜生成条件、Fe3O4行为、铜在渣中损失以及铜直收率等因素的影响。结果表明：相对于其他3种炉型,甩渣吹炼双烟道D型炉是比较理想的连续炼铜炉体;对于闪速连续炼铜,造锍熔炼段和铜锍吹炼段宜在相对独立的分区进行,各自炉渣和烟气也应分开排出炉体。     

Mass balance calculations in copper flash smelting by means of genetic algorithms

This paper presents mass balance calculations using genetic algorithms for copper smelting in an Outokumpu flash furnace. Based on the elemental composition of the copper concentrates being fed to the reactor, the mineralogical composition of the concentrate mixture is adjusted by means of genetic algorithms. The macroscopic mass balance equations for the species entering and leaving the furnace are solved and the compositions and flow rates of matte, slag, and the off-gas stream are computed. Good agreement between the predicted and plant data was obtained in terms of matte and slag flow rates, matte grade, and copper, iron, magnetite, and silica contents in the slag. Predictions are more suitable and faster to obtain with this method than a conventional method in which the mineralogical composition of the feed is not adjusted. Future applications of the formulation are discussed. For more information, contact V.M. Sanchez-Corrales, Universidad de Sonora, Departamento de Ingeniería Química y Metalurgia, Blvd. Luis Encinas y Rosales, Hermosillo, Sonora, 83000, Mexico; +662-259-2105; fax +662-259-2105; e-mail vsanchez@guaymas.uson.mx.     

EFFECTS OF TEMPERATURE ON DISTRIBUTION BEHAVIORS OF MINOR ELEMENTS IN COPPER FLASH SMELTING──COMPUTER SIMULATION

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Direct Production of Copper

The use of commercially pure oxygen in flash smelting a typical chalcopyrite concentrate or a low grade comminuted matte directly to copper produces a large excess of heat. The heat balance is controlled by adjusting the calorific value of the solid feed. A portion of the sulfide material is roasted to produce a calcine which is blended with unroasted material, and the blend is then autogeneously smelted with oxygen and flux directly to copper. Either iron silicate or iron calcareous slags are produced, both being subject to a slag cleaning treatment. Practically all of the sulfur is contained in a continuous stream of SO₂ gas, most of which is strong enough for liquefaction. A particularly attractive feature of these technologies is that no radically new metallurgical equipment needs to be developed. The oxygen smelting can be carried out not only in the Inco type flash furnace but in other suitable smelters such as cyclone furnaces. Another major advantage stems from abolishion of the ever-troublesome converter aisle, which is replaced with continuous roasting of a fraction of the copper sulfide feed.     

Numerical analysis on fluid flow and heat transfer in the smelting furnace of mitsubishi process for Cu refining

To understand complex behavior in the smelting furnace of Mitsubishi continuous process for copper refining, comprehensive 3-D numerical simulation and field experiment were performed. The numerical simulation results showed that strong and complex velocity fields of gas, matte and slag were generated in the furnace and large amounts of matte and slag were splashed into the gas area. Temperature measurements at the lance during field operation revealed that wide range of temperature variation appeared depending on the injection condition of concentrates. Numerical simulation results provided good agreements with experiments results and showed that the chemical reaction induces temperature increase during gas injection period. On the other hand, lance temperature is decreasing because of cold concentrates during gas and particles injection period. From the FFT analysis results, the fluctuations of matte and slag volume fraction near the lance induce temperature fluctuations of the lance. Through these experimental and simulation results, it was revealed that the lances in the smelting furnace were exposed to severe conditions such as high temperature, repeated large temperature change and cyclic change of large temperature gradient across the thickness.     

Thermodynamic Assessment of Slag–Matte–Metal Equilibria in the Cu-Fe-O-S-Si System

Equilibria among the slag, matte and metal phases in the Cu-Fe-O-S-Si system are critically assessed using thermodynamic modeling. The relationships among matte grade, temperature, partial pressure of SO₂, Fe/SiO₂ in the slag, and the copper concentration in the slag are described by the model, as well as the concentrations of other elements in all phases. A thermodynamic database is created, which can be used for understanding and improving the pyrometallurgical production of copper. An extensive experimental dataset includes the most recent results obtained by the equilibration/quenching/EPMA analysis technique. These data allow to distinguish the physical entrainment of the matte and solid phases in the slag from chemical solubility. As a result, it is possible to describe the copper solubility in the slag with high accuracy and establish the relationship between copper and sulfur in the slag. The thermodynamic database of the present study is consistent with previously reported thermodynamic evaluations of binary, ternary and quaternary subsystems. The slag phase is modeled using the two-sublattice modified quasichemical model in the quadruplet approximation. The matte and metal liquid phases are modeled as one solution using the single-sublattice modified quasichemical model in the pair approximation.     

铜闪速炉沉淀池渣中锍液滴沉降机理及其影响因素

通过分析沉淀池内锍液滴的沉降机理,导出了渣中最大锍液滴直径的计算公式。根据闪速炉的实际生产条件,计算出渣中最大锍液滴直径的理论值为0.063 mm,并用矿相显微镜对沉淀池出口处的渣样进行了观察,渣中最大锍颗粒粒径为0.06 mm,两者结果一致。由此证明了沉降机理分析的正确性。在此基础上,进一步分析渣中锍夹带损失影响因素。结果表明:增大熔体中离散态分布的锍液滴直径是降低渣中铜夹带损失的重要措施;其次是升高渣温度有助于渣中锍的沉降;减小渣层厚度等措施对降低渣中铜夹带损失作用不大。     

Continuous Converting of Copper Matte to Blister Copper in a High-Intensity Molten-Layer Reactor

Continuous converting of copper matte or white metal into blister copper is carried out in a new, high-intensity falling film type of molten-layer reactor that operates with dry, high-grade matte or white metal ground to ?65 mesh and technical oxygen. The reactor operates at up to 1500°C to 1600°C producing a blister copper with 0.5–0.8% S, which can be refined in a conventional manner, and a slag containing less than 8% Cu. The reactor is designed to operate continuously producing an off-gas containing over 50% SO₂. The developed phenomenological model of the molten-layer reactor was found to predict with good agreement the results obtained in a one-tonne-per-day pilot reactor.     

Moderate Dilution of Copper Slag by Natural Gas

To enable use of copper slag and extract the maximum value from the contained copper, an innovative method of reducing moderately diluted slag to smelt copper-containing antibacterial stainless steel is proposed. This work focused on moderate dilution of copper slag using natural gas. The thermodynamics of copper slag dilution and ternary phase diagrams of the slag system were calculated. The effects of blowing time, temperature, matte settling time, and calcium oxide addition were investigated. The optimum reaction conditions were identified to be blowing time of 20 min, reaction temperature of 1250°C, settling time of 60 min, CaO addition of 4% of mass of slag, natural gas flow rate of 80 mL/min, and outlet pressure of 0.1 MPa. Under these conditions, the Fe₃O₄ and copper contents of the residue were 7.36% and 0.50%, respectively.     

Flash smelting copper concentrates

Flash smelting is a comparatively new method of smelting copper and nickel sulfide concentrates. It takes place when the concentrate, with or without additional fuel, is suspended in gases containing oxygen whereby the heat of oxidation reactions bring the suspended particles to a smelting temperature. From the suspended state the hot particles are separated and molten slag and matte are deposited on the furnace hearth.     

含钴铜转炉渣的工艺矿物学

研究了铜转炉渣的化学与矿物学特征,用光学显微镜查明了炉渣各主要渣相为铁橄榄石,磁铁矿和无定形玻璃体,铜主要以冰铜相裹夹于渣相中,铜滴的尺度与渣的冷却历史有关。用X射线衍射谱,扫描电子显微镜,X射线能谱和X射线波谱及化学物相分析,对铜和钴的赋存状态及在各相中的分布进行了表征和量化。结果表明,钴主要以类质同象形式取代铁橄榄石和磁铁矿晶格中部分Fe^2 ,作为氧化物富集其中,二者约占钴总量的95％,渣中钴的提取需要以铁橄榄石和磁铁矿的分解为前提,使钴的氧化的游离出来而酸溶。     

Copper smelting mechanism in oxygen bottom-blown furnace

The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace, however, the oxygen enriched air is blown into the furnace from the bottom. Mechanism model of the SKS process was developed by analyzing the smelting characteristics deeply. In our model, the furnace section from top to bottom is divided into seven functional layers, i.e., gas layer, mineral decomposition transitioning layer, slag layer, slag formation transitioning layer, matte formation transitioning layer, weak oxidizing layer and strong oxidizing layer. The furnace along the length direction is divided into three functional regions, that is, reaction region, separation transitioning region and liquid phase separation and settling region. These layers or regions play different roles in the model in describing the mechanism of the smelting process. The SKS smelting is at a multiphase non-steady equilibrium state, and the oxygen and sulfur potentials change gradually in the length and cross directions. The smelting capacity of the SKS process could be raised through reasonably controlling the potential values in different layers and regions.     

Thermodynamic analysis and process optimization of zinc and lead recovery from copper smelting slag with chlorination roasting

An efficient chlorination roasting process for recovering zinc (Zn) and lead (Pb) from copper smelting slag was proposed. Thermodynamic models were established, illustrating that Zn and Pb in copper smelting slag can be efficiently recycled during the chlorination roasting process. By decreasing the partial pressure of the gaseous products, chlorination was promoted. The Box−Behnken design was applied to assessing the interactive effects of the process variables and optimizing the chlorination roasting process. CaCl₂ dosage and roasting temperature and time were used as variables, and metal recovery efficiencies were used as responses. When the roasting temperature was 1172 °C with a CaCl₂ addition amount of 30 wt.% and a roasting time of 100 min, the predicted optimal recovery efficiencies of Zn and Pb were 87.85% and 99.26%, respectively, and the results were validated by experiments under the same conditions. The residual Zn- and Pb-containing phases in the roasting slags were ZnFe₂O₄, Zn₂SiO₄, and PbS.     

Chemical Degradation Mechanisms of Magnesia–Chromite Refractories in the Copper Smelting Furnace

Magnesia–chromite refractory has been extensively used in the copper-making industry. It is necessary to understand the degradation mechanisms of the current refractory to develop new refractories. In the present study, post mortem refractories from a smelting furnace were analyzed and compared with the results of static corrosion tests on magnesia–chromite refractories in the laboratory at high temperatures. The microstructure and phase composition were carefully investigated by electron probe x-ray microanalysis to understand the degradation mechanisms of the magnesia–chromite refractory in copper smelting conditions. The degradation mechanisms between the magnesia–chromite refractory and the copper smelting slag and CuO transformed from matte are discussed based on the analysis of the post mortem refractory samples and laboratory tests. These results will enable optimization of the industrial process and development of new refractories for copper smelting furnaces.