Advances in Understanding of Unit Operations in Non-ferrous Extractive Metallurgy 2021

• Other Authors: Stopic, Srecko (Editor), Friedrich, Bernd (Editor)
• Format: Electronic Book Chapter
• Language: English
• Published: Basel MDPI - Multidisciplinary Digital Publishing Institute 2022
• Subjects: Technology: general issues; History of engineering & technology; Mining technology & engineering; zirconium; eudialyte; hydrometallurgy; basic sulfate precipitation; macroporous polymer; goethite; factorial design; desorption; tailings reprocessing; early stage cost estimation; magnetic separation; leaching; flotation; silica; ultrasonic spray pyrolysis; synthesis; acid mine drainage; red mud; neutralization; immobilization; precipitation; nitinol; continuous vertical cast (CVC), NiTi rod; atomic layer deposition; corrosion properties; potentiodynamic test; electrochemical impedance spectroscopy; rare earth elements; recycling; NdFeB; magnet; non-ferrous metals; cavitation erosion; optical microscopy; electron microscopy; atomic force microscopy; aluminium; thin-layer electrolysis; molten salts; halides; capillary cell; electrorefining; non-commercial copper anode; waste solution; high content; Ni; Pb; Sn; Sb; passivation; anode slime; pentlandite; oxidation; reaction mechanism; phase analysis; silver; copper; nanoparticles; antibacterial; MnO2; cobalt oxide Co3O4; perovskite materials; oxygen reduction in alkaline media; electrocatalyst; Pt catalyst; nanocomposite; mixed oxides; NiAl2O4; ZnAl2O4; electrocatalysis; nanocatalyst; noble metal nanoparticles; leachate; metal ions extraction; selectivity; Fe removal; electrodeposition; conductometry; n/a
• Online Access: DOAB: download the publication; DOAB: description of the publication

Unit 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.