Abstract: The process will recover sulfuric acid on the 90-95% concentration range by roasting of ferrous sulfate hydrate crystals at high temperature under retort conditions. In the first step of the recovery process 6 (see FIG. 1) hydroxide slurry is reacted with the waste stream, and ferrous sulfate crystals obtained. In the second step 9 iron sulfate crystals are roasted and water of hydration reacts with sulfate and sulfur trioxide to produce sulfuric acid in a retort operation. The sulfuric acid and sulfur trioxide are condensed or absorbed in water or dilute sulfuric acid and are of a high purity, leaving iron oxide as a recovered carrier. In the third step, this iron oxide/hydroxide is reduced 13 and used to produce a slurry, which is pumped back to react with the entering sulfuric acid waste stream.