Extracting silica and alumina from low-grade bauxite

The unit shown schematically in Figure 4 is designed for the agitation leaching procedure. Finely ground (-2 mm) calcined bauxite was dosed from a bunker by feeder to a rod mill (L = 3 m, D = 1 m) revolving at 32 rpm. Initially, the heated alkali solution at 90-95[degrees]C was fed to the mill with pump and batcher. The alkali-bauxite slurry with a liquid-to-solid ratio of 5:1 was delivered into two in-line stirrers by pumps.