BigPatents India

The present invention relates to “an improved process for purification of phosphogypsum”. The improved process of the present invention will be particularly useful for the purification of phosphogypsum, a by-product of the phosphoric acid, by removal of the harmful impurities of phosphates, fluorides, organic matter and alkalis. The purified phosphogypsum will find use in the production of building materials. The improved process of the present invention consists of extracting impurities of P2O5, F, organic matter and alkalis present in phosphogypsum with aqueous citric acid solution, followed by washing of the leached impurities with a stream of water, drying the gypsum cake at 40-50oC to constant weight.