METHOD FOR OBTAINING OR RECOVERING NITRIC ACID AND HYDROFLUORIC ACID FROM SOLUTIONS OF STAINLESS STEEL PICKLING SYSTEMS

摘要

A method for obtaining or recovering acids, in particular nitric acid and hydrofluoric acid, from solutions and/or metal salts of these acids containing solutions, comprising the steps of: a) spray-drying the solutions at temperatures below the decomposition temperature of the acids, the requisite energy for which is introduced via a gaseous heat-transfer medium, in order to obtain dry metal salts and gaseous acids; b) absorbing the gaseous acids formed in step a); c) separating out the dry metal salts formed in step a); optionally d) roasting the dry metal salts obtained in step a) at temperatures in the range from 400 to 900° C., in order to obtain metal oxides and gaseous acids; and e) absorbing the gaseous acids formed in step d).