Patent ID: 7351391
Filing Date: 2008-04-01
Classification: C01B,C01G,C23G,Y10S

Abstract:
1. A method of converting a spent first pickling acid solution that contains hydrochloric acid, water and ferrous chloride into a second pickling acid solution, said method comprising the steps of: adding sulfuric acid to said spent first pickling acid solution to produce a regeneration solution, wherein said sulfuric acid reacts with said ferrous chloride and water while at ambient pressure to produce ferrous sulfate heptahydrate and hydrogen chloride; cooling said regeneration solution to promote precipitation of said ferrous sulfate heptahydrate from said regeneration solution, therein creating ferrous sulfate heptahydrate crystals and a second pickling acid solution containing both hydrochloric acid and sulfuric acid; separating said ferrous sulfate heptahydrate crystals from second pickling acid solution.