Patent ID: 6375915
Filing Date: 2002-04-23
Classification: C23G,Y10S

Abstract:
In a method of regenerating a spent pickling solution composed of nitric acid and hydrofluoric acid and containing metal fluorides and metal nitrates, the method including heating the pickling solution in a fluidized bed reactor to a temperature of about 300-1,000Â° C., pyrohydrolyzing the metal fluorides and metal nitrates so as to produce a gas and metal oxides in the form of a granulate, removing the granulate from the fluidized bed reactor and dedusting and cooling the gas produced in the fluidized bed reactor and feeding the cooled gas to an acid recovery unit, the improvement comprising separating the spent pickling solution in a separating process into a partial flow enriched with free acid and a partial flow enriched with metal salts, and feeding the partial flow enriched with free acid to the acid recovery unit and feeding the partial flow enriched with metal salts to the fluidized bed reactor.