System and method for converting the spent remnants of a first pickling acid solution into a usable second pickling acid solution

Abstract

A system and method of economically converting a spent first pickling acid solution that contains hydrochloric acid, water and ferrous chloride into a suitable second pickling solution. Sulfuric acid is added to the first pickling acid solution. This produces a regeneration solution. In the regeneration solution, the sulfuric acid reacts with said ferrous chloride and water to produce ferrous sulfate heptahydrate and hydrochloric acid. The regeneration solution is cooled to promote precipitation of the ferrous sulfate heptahydrate from the regeneration solution, therein creating ferrous sulfate heptahydrate crystals and a second pickling acid solution. The second pickling acid solution contains both hydrochloric acid and sulfuric acid. The ferrous sulfate heptahydrate crystals are separated from second pickling solution. The ferrous sulfate heptahydrate is sold commercially and the second pickling acid solution is used to directly pickle ferrous metal.

Dependencies are inferred from the claim text.