Study of the physical and chemical properties of aluminum slags

The paper presents the results of a study of the physicochemical and mineralogical properties of primary and secondary aluminum slags. It was found that the primary aluminum slags contain 67.8% Al₂O₃, 12.4% SiO₂, 4.58% MgO, 4.59% CaO, and 0.52% Fe₂O₃. The main phases are spinel (25.4%), sapphirine (26.0%), corundum (25.0%), enstatite (11.9%), and mullite (11.7%). These high-temperature aluminosilicate and oxide phases have high thermodynamic stability and low chemical activity, which significantly complicates the processing of primary slags. The secondary aluminum slags contain 34.9% Al₂O₃, 4.61% SiO₂, 34.7% CaO, 5.70% MgO, and 4.71% Fe₂O₃. The mineral composition comprises spinel (20.5%), quartz (10.5%), mullite (8.0%), corundum (13.1%), calcite (27.0%), and breyite (20.9%). Complex aluminosilicate compounds were not detected in the secondary slags, which determines their higher reactivity. The potential of using secondary aluminum slags in metallurgical processing is demonstrated, in particular in the production of ferrosilicon in the form of pellets with the addition of ferrosilicon metal fines, which allows for a reduction in the consumption of natural silica materials and an increase in the resource efficiency of production. The results obtained can be used in the development of energy- and resource-saving technologies for processing aluminum waste.