Method of recovering hydrochloric acid from spent hydrochloric acid pickle waste

Abstract

A method of recovering hydrochloric acid from spent hydrochloric acid pickle liquor is used to increase the amount of hydrochloric acid recovered and to improve the form of the waste products for better handling and reduced energy costs. The waste pickle liquor from the pickle line is first concentrated before the liquor is reacted in a double exchange process with strong sulphuric acid. The concentrator separates the weak pickle into two streams consisting of an overhead vapor stream and an underflow of strong pickle liquor. The overhead vapor stream separates out hydrochloric acid by means of a fractionator with the underflow of strong pickle liquor being fed to the double exchanger reactor to be mixed with the sulphuric acid. The overhead from the reaction process which consists of hydrogen chloride and water vapor is condensed and made available for addition to the fractionated hydrogen chloride. The remaining products of the double exchange reaction are filtered to form ferrous sulphate monohydrate crystals.

Dependencies are inferred from the claim text.