Patent ID: 7399454
Filing Date: 2008-07-15
Classification: C22B,Y02P,Y10S

Abstract:
1. A method of treating metallurgical dust, the method comprising: (a) washing the metallurgical dust with water to remove halides, the metallurgical dust comprising halides, iron and one or more non-ferrous metals; (b) leaching the metallurgical dust with nitric acid solution at ambient pressure and separating the leached metallurgical dust; and (c) reacting at a pressure of at least about 50 psig and at a corresponding temperature of at least about 100° C. the leached metallurgical dust with another quantity of nitric acid solution to dissolve at least a portion of the non-ferrous metal compositions into the solution which is in contact with solid ferric oxide wherein the metallurgical dust is an iron bearing hazardous waste, and wherein the solid ferric oxide is a non-hazardous waste comprising at most about 0.5 mg/L As, 7.6 mg/L Ba, 0.33 mg/L Cr, 0.001 mg/L Hg, 1.0 mg/L Ni, and 0.15 mg/L Pb.