Breaking the Fe_(3)O_(4)-wrapped copper microstructure to enhance copper-slag separation

The precipitation of Fe_(3)O_(4)particles and the accompanied formation of Fe_(3)O_(4)-wrapped copper structure are the main obstacles to copper recovery from the molten slag during the pyrometallurgical smelting of copper concentrates.Herein,the commercial powdery pyrite or anthracite is replaced with pyrite-anthracite pellets as the reductants to remove a large amount of Fe_(3)O_(4)particles in the molten slag,resulting in a deep fracture in the Fe_(3)O_(4)-wrapped copper microstructure and the full exposure of the copper matte cores.When 1wt%composite pellet is used as the reductant,the copper matte droplets are enlarged greatly from 25μm to a size observable by the naked eye,with the copper content being enriched remarkably from 1.2wt%to 4.5wt%.Density functional theory calculation results imply that the formation of the Fe_(3)O_(4)-wrapped copper structure is due to the preferential adhesion of Cu_(2)S on the Fe_(3)O_(4)particles.X-ray photoelectron spectroscopy,Fourier transform infrared spectrometer(FTIR),and Raman spectroscopy results all reveal that the high-efficiency conver-sion of Fe_(3)O_(4)to FeO can decrease the volume fraction of the solid phase and promote the depolymerization of silicate network structure.As a consequence,the settling of copper matte droplets is enhanced due to the lowered slag viscosity,contributing to the high efficiency of copper-slag separation for copper recovery.The results provide new insights into the enhanced in-situ enrichment of copper from mol-ten slag.

Chemical Characterization of Slags from an Old Smelter in Chihuahua, Mexico

Slag is waste from pyrometallurgical processing, usually stored in stacks or warehouses around or near smelters. Slag research has focused on potential environmental problems associated with slag weathering or processing for secondary metal recovery and/or other uses (construction, landscaping, etc.). Located in northern Mexico, the city of Chihuahua has a mining history that dates back to the eighteenth century. A lead smelter located southeast of Chihuahua City;closed in 1997, leaving behind a large pile of slag. In this study, a chemical analysis of smelter slag was carried out. The tailings contain Zn (15 - 35 wt%), Pb (0.5 - 4 wt%), As (0.6 wt%), Sn (888 ppb) and Hg (170 ppb). XRD identified several minerals such as hardystonite (Ca2ZnSi2O7), melanotekite (), kentrolite () and sphalerite (ZnS) in the glass. Major elements are present in phases such as monticellite (CaMgSiO4), kirschsteinite (CaFe2+SiO4), hedenbergite (CaFe2+Si2O6), babingtonite (Fe2Si3O9), magnetite (Fe3O4), and calcite (CaCO3). Whether the goal is reuse, recycling or remediation, research into the properties of slag and its environmental and health impacts (on vulnerable exposed populations) should continue to be relevant.

Recent advances in the recovery of transition metals from spent hydrodesulfurization catalysts

Hydrodesulfurization(HDS)catalysts are widely used in petrochemical industries,playing a crucial role in desulfurization process to get high-quality oil.The generation of Al-based spent HDS catalyst is estimated to be 1.2×105 tons per year around the world.The spent HDS catalysts have been regarded as an important secondary resource due to their abundant output,considerable metal value,and regeneration potential;however,if improperly handled,it would severely pollute the environment due to high content of heavy metals.Thus,the recovery of valuable metals from spent HDS catalysts is of great importance from both resource utilization and environmental protection points of view.In this work,recent advances in the spent HDS catalyst treatment technologies have been reviewed,focusing on the recovery of valuable transition metals and environmental impacts.Finally,typical commercial processes have been discussed,providing in-depth information for peer researchers to facilitate their future research work in designing more effective and environmentally friendly recycling processes.