Purification of Gypsum from Phosphoric Acid Production by Recrystallization with Simultaneous Extraction.

摘要

In the wet phosphoric acid production processes, not only phosphoric acid is formed from the reaction of phosphate ore with sulfuric acid, but also a large amount of gypsum amounting to 100 billion kg worldwide (2.3 kg per kg phosphoric acid). Until the development of the ProGrips process in 1999, the gypsum had to be disposed of due to incorporated impurities. Simultaneous extraction during the recrystallization of calcium sulfate hemihydrate to dehydrate (gypsum), which is discussed in this thesis, is a technique, which can be implemented in the production process complementary to or instead of the ProGrips process to produce a cleaner and sustainable phosphoric acid and gypsum project. A large advantage of the extraction process is that the production process will become for flexible with respect to the ores, which can be consumed. The developed in-line extraction techniques can also be used for other solid-liquid process streams.