Patent ID: 6548038
Filing Date: 2003-04-15
Classification: C01B,Y02P,Y10S

Abstract:
A process for increasing the concentration of sulphuric acid in a solution of waste acid containing 10-30% sulfuric acid and further containing metal salts using a multistage heat exchanger vacuum evaporator system, comprising the steps ofa) feeding the dilute acid to the first evaporator stage of the multistage evaporator system operating at an acid concentration of less than 30%; b) feeding part of the acid from step (a) to a heat exchanger/vacuum evaporator system heated using waste heat and operating at an acid concentration greater than 40%, and c) feeding the acid from step (b) with the remainder of the acid from step (a) to the second stage of the multistage system operating at an acid concentration greater than 50% and recycling steam generated in the second stage evaporator as the heating medium for the first stage.