293 research outputs found
Feature Papers in Extractive Metallurgy
No full textExtractive metallurgy deals with the processes for the recovery of valuable metals from ores and concentrates (primary metallurgy) or waste raw materials such as slags, slime, and flying ashes (recycling or secondary metallurgy). Regarding the type of obtained metals, these processes are divided into five different groups: extractive metallurgy of iron and steel, non-ferrous extractive metallurgy, extractive metallurgy of precious metals, extractive metallurgy of rare earth elements, and refractory metal extractive metallurgy. These processes in extractive metallurgy include unit processes for separating highly pure metals from undesirable metals in an economically efficient system. Extractive metallurgy is based on unit metallurgical operations that are usually separated into three categories: 1) hydrometallurgy (leaching, mixing, neutralization, precipitation, cementation, and crystallization); 2) pyrometallurgy (roasting and smelting); and 3) electrometallurgy (aqueous electrolysis and molten salt electrolysis)
Advances in Understanding of Unit Operations in Non-ferrous Extractive Metallurgy 2021
No full textUnit metallurgical operations processes are usually separated into three categories: 1) hydrometallurgy (leaching, mixing, neutralization, precipitation, cementation, and crystallization); 2) pyrometallurgy (roasting and smelting); and 3) electrometallurgy (aqueous electrolysis and molten salt electrolysis). In hydrometallurgy, the aimed metal is first transferred from ores and concentrates to a solution using a selective dissolution (leaching or dry digestion) under an atmospheric pressure below 100 °C and under a high pressure (40-50 bar) and high temperature (below 270°C) in an autoclave. The purification of the obtained solution was performed using neutralization agents such as sodium hydroxide and calcium carbonate or more selective precipitation agents such as sodium carbonate and oxalic acid. The separation of metals is possible using a liquid/liquid process (solvent extraction in mixer-settler) and solid–liquid (filtration in filter-press under high pressure). Crystallization is the process by which a metallic compound is converted from a liquid into a solid crystalline state via a supersaturated solution. The final step is metal production using electrochemical methods (aqueous electrolysis for basic metals such as copper, zinc, silver, and molten salt electrolysis for rare earth elements and aluminum). Advanced processes, such as ultrasonic spray pyrolysis and microwave-assisted leaching, can be combined with reduction processes in order to produce metallic powders
Advances in Synthesis of Metallic, Oxidic and Composite Powders
No full textAdvances in synthesis of metallic, oxidic and composite powders were presented via the following methods: ultrasound-assisted leaching¸ ultrasonic spray pyrolysis, hydrogenation, dehydrogenation, ball milling, molten salt electrolysis, galvanostatic electrolysis, hydrogen reduction, thermochemical decomposition, inductively coupled thermal plasma, precipitation and high pressure carbonation in an autoclave. This Special Issue contains 17 papers from Europe, Asia, Australia, South Africa and the Balkans. The synthesis was focused on metals: Co, Cu; Re; oxides: ZnO, MgO, SiO2; V2O5; sulfides: MoS2, core shell material: Cu-Al2O3, Pt/TiO2; compounds: Ca0.75Ce0.25ZrTi2O7, Mo5Si3, Ti6Al4V. The environmentally friendly strategies were presented at the carbonation of olivine, treatment of acid mine drainage water and production of vanadium oxide
Special Issue "Advances in Understanding of Unit Operations in Non-ferrous Extractive Metallurgy 2021"
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