METHOD OF ALUMINOTHERMIC PRODUCTION OF METAL CHROMIUM Russian patent published in 1998 - IPC

FIELD: nonferrous metallurgy. SUBSTANCE: method includes stepped loading and melting charge containing chromium oxide, oxidant, lime, and aluminum, after which molten products are discharged. In the first step, charge to be melted contains (in % based on total weight of components in the overall process): chromium oxide, 53-64; oxidant, 60-80; lime, 30-40, and aluminum in quantity constituting 0.8-0.94 stoichiometrically required amount to reduce chromium oxide, charge loading rate being 180-280 kg/sq.m. In the second step, corresponding values are as follows: 36-47, 20-40, 60-70, 1.02-1.2, and 170-275. When chromium metal with low nitrogen content (at most 0.05%) is produced, charge in the both steps contains, as oxidant, chromic anhydride and potassium bichromate or sodium with added calcium hydroxide, sodium chloride, and fluorite concentrate in proportion to the weight of used chromium oxide: (0.1-0.2):(0.02-0.04):(0.03-0.08):(0.001-0.02):(0.001-0.02):1. EFFECT: enhanced efficiency of process. 2 cl, 1 tbl