Selective and Efficient Extraction of Zinc from Mixed Sulfide–oxide Zinc and Lead Ore

Mixed sulfide–oxide lead and zinc ores are generally composed of both sulfides and oxides. The dissolution of sulfides is more difficult than oxides thus the addition of oxidant is necessary. In this paper, oxidative leaching of mixed ore in NH₃-(NH₄)₂SO₄ solution using ammonium persulfate as oxidant under atmospheric pressure and relatively low temperature was investigated for the first time. The effects of factors on the leaching of pure ZnS were studied and the optimal conditions with zinc 98.7% were determined. Selective and efficient extractions of 93.9% and 94.9% zinc from zinc sulfide ore and mixed ore were also achieved, respectively.     

Efficient Recovery of Copper and Cobalt from the Matte–Slag Mixture of ISA Furnace by Injection of Coke and Pyrite

During ISA copper smelting process, ISASMELT furnace discharges a large amount of matte and slag mixture and the separation of them has an important influence on the recovery of valuable metals. This paper presented a reduction-sulfurization sedimentation process for recovering copper and cobalt from the matte–slag mixture of ISA furnace. Firstly, matte–slag mixture and traditional static sedimentation slag are characterized to determine their mineral composition and occurrence state. It indicates that Cu is primarily lost in slag in the form of sulfide, while Co is mostly lost in the form of oxide. With coke and pyrite as the reducing agent and vulcanizing agent, an orthogonal laboratory experiment was conducted to determine the effects of the smelting temperature and additive dosage on the recovery process. The optimum slag cleaning conditions were found to be: a coke dosage of 2 pct, a pyrite dosage of 2 pct, and a smelting temperature of 1260 °C lasting for 2 hours. In order to improve on the low utilization ratio of additives associated with the industrial sedimentation process, an innovative additive introducing method was put forward which enables the additives to mix and react with slag more adequately. A powder injection device was purpose-made to inject additives into molten slag in dispersion state, and a laboratory experiment was carried out to simulate this process. By injecting 2 pct coke and 2 pct pyrite, the contents of Cu and Co in cleaned slag decreased to 0.46 and 0.01 pct, respectively. It proves that the injection of additives into molten slag is an effective method to recover Cu and Co from the matte–slag mixture of ISA furnace.     

Evolution of Texture,Strain, and Grain Boundary Constitution in Copper–Chromium Coatings and its Effect on Coating Corrosion Behavior

Metallurgical and Materials Transactions A - Microstructural alterations in electrodeposited Cu–Cr coatings (1.5, 3.6, and 6.5 wt pct Cr) and their impact on the coating corrosion behavior...     

Recovery of Cobalt,Copper and Zinc from Küre-Kastamonu Historical Copper Slag by High Pressure Oxidative Acid Leaching

Russian Journal of Non-Ferrous Metals - Copper slags are solid by-products formed during the copper production process by pyrometallurgical method from sulfide copper ores. These slags usually...     

Cooling Process and Cast Structure of Zr-Al-Ni-Cu–Based Bulk Metallic Glasses Produced in Various Atmospheres

Cooling process in the production of Zr₆₅Al_7.5Ni₁₀Cu_17.5-based bulk metallic glasses (BMGs) was investigated in various chamber atmospheres in Cu mold casting. Two different cooling modes, consisting of the direct heat transfer between the melt and Cu mold in the high temperature and indirect transfer via cavity in the low-temperature regions, are suggested. In the later case, the cooling effect should depend on the chamber atmosphere, which results in the formation of glassy structure with large relaxation enthalpy casting under the ambient Ar and He atmospheres due to a good thermal conductivity. The less relaxed BMGs produced by an improved cooling effect are also expected to contain a large amount of free volume for significant deformability. Actually, it is clarified that the compressive plastic deformation is improved with an increase of the relaxation enthalpy. The present study indicates a necessity of development of the glassy structure, i.e., relaxation state, and provides a new technique of the formation of less relaxed glassy structure for the improvement of plasticity in BMGs.     

Investigation into the Structure Formation and Properties of Materials in the Copper–Titanium Disilicide System

The structure formation and properties during infiltration, free sintering, and spark-plasma sintering in Cu–(12.5–37.5 vol %) powder materials Ti₃SiC₂ are investigated by electron microscopy, X-ray phase analysis, and energy-dispersion analysis. The independence of the phase composition of composite materials (CMs) on the sintering method and temperature in a range of 900–1200°C is established. The peculiarities of formation of the CM structure during sintering are the intercalation of silicon from titanium carbosilicide and the formation of a carbon solid solution based on Ti₅Si₃(C) titanium disilicide, small amounts of titanium carbide, silicon carbide, and TiSi₂ silicide. An increase in Ti₃SiC₂ in the CM certainly lowers electrical conductivity, but considerably increases the hardness, strength, and electroerosion wear resistance of CM electrodes for electroerosion broaching.     

Dependence of the Grain Size in the Microstructure of Copper on the Rate of Deformation by “Helical Rolling–Pressing”

Metallurgist - The authors consider the refinement of the microstructure of copper (grade M1) on the rate of deformation using a “helical rolling-pressing” method. The deformation was...     

Effect of Fe2+ and Surfactant on Low-Grade Copper–Molybdenum Ore Bioleaching and Process Optimization by Response Surface Methodology

Russian Journal of Non-Ferrous Metals - The process of low-grade copper–molybdenum ore bioleaching in the simultaneous presence of Fe2+ and Tween-20 was optimized by response surface...     

Electrical Conductivity and Strength Changes in Green Compacts of Iron Powder When Heated in Range 50–400°C in Air

Abstract

Based on considerable technological development and comprehensive work in process engineering, a method has been developed for short-time induction sintering of hardmetals which combines increased production throughput with savings in treatment time and improvement of the final product. The process is applicable to conventional WC–Co and WC–TiC–Co hardmetals and can be readily transferred to other cemented carbide systems. PM/0217     

Increasing the Stability of Mechanical Properties of Semifinished Products from Ti–6Al–4V Alloys by Correcting the Alloying Range and Annealing Modes

Metallurgist - Statistical studies on the stability of the mechanical properties of various semifinished products made from Ti–6Al–4V alloys depending on the content of alloying...     

Improving the Estimation Accuracy of Copper Oxide Leaching in an Ammonia–Ammonium System Using RSM and GA-BPNN

In this study, a response surface methodology (RSM) model was used to analyze and optimize the factors affecting copper leaching efficiency in a copper oxide ammonia-ammonium (AA) system based on the parameters of AA concentration (ammonium hydroxide and ammonium bicarbonate matched with 1: 1), leaching time, grinding fineness, liquid-solid ratio, and temperature. The RSM analysis showed that five individual variables had a significant influence and that the interaction between AA concentration and leaching time had the most significant influence on leaching efficiency. In order to improve the estimation accuracy of the copper leaching efficiency, a model consisting of a genetic algorithm and a back propagation neural network (GA-BPNN) was used to optimize the operation index. A back propagation feed forward neural network with 3 layers (5–10–1) was applied to predict copper leaching efficiency. The genetic algorithm was applied to analyze the optimal leaching conditions. The results revealed that the GA-BPNN model outperformed the RSM model for predicting and optimizing copper oxide AA leaching. The optimization results of the GA-BPNN resulted in an R² of 0.99827 and the highest predicted copper leaching efficiency of 79.49% was obtained under the conditions of an AA concentration of 4.78 mol/L, a leaching time of 157 min, a grinding fineness of 86.86% (–74 μm content account), a liquid-solid ratio of 2.87: 1, and a temperature of 313.17 K. A prediction and optimization method combining RSM and GA-BPNN, as used in this paper, can be further employed as a reliable and accurate method for ore leaching.