Alumina comminution

The HogenSs process is widely used for the production of reduced metal powders [32.24]. In the production of iron powder, for example, pure magnetite ores are comminuted, screened and purified using magnetic separators. They are then mixed with a blend of coke and quicklime, and heated in a silicon carbide lined retort at 1050 to 1200 °C for 24 to 40 hours. The iron oxide is reduced by the coke to iron and the quicklime reacts with sulfur, silica and alumina in the ore and coke, forming a slag. 

Alunite [Kz Al6(QH)i2 (504)4 is a potential source of potassium sulfate, alumina, and sulfur dioxide byproduct. The economics of production hinge on the value of the alumina. Processing involves ore comminution, roasting, and leaching to recover potassium sulfate solution. Filtered solids can be processed in a Bayer-type process plant for alumina recovery [111]. 

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