Process for treating phospho-gypsum waste product from wet-acid process of making phosphoric acid

摘要

This disclosure concerns a process for treating phospho-gypsum waste product from the wet process method of making phosphoric acid including the steps of water washing the phospho-gypsum to remove all but an acceptable level of fluorine before the phospho-gypsum is calcined. The process allows the use of high sulfur coal for the production of steam if desired for use in the overall process. The process also allows for production of SO3 from part of the phospho-gypsum in an electric furnace to enrich the SO2 stream for making sulfuric acid.