Production of high-quality gypsum raw materials from phosphogypsum

Possibility of obtaining high-quality gypsum products from phosphogypsums produced in sulfuric acid processing of the Khibiny apatite concentrate was examined. A variant of phosphogypsum processing including the sulfuric acid leaching of rare-earth elements and admixtures of phosphorus and fluorine compounds, neutralization of the purified gypsum product, and utilization of phosphates and fluorides released from phosphogypsum was considered. It was experimentally demonstrated that the agitation sulfuric acid leaching is inefficient for purification of phosphogypsums. It was confirmed that combining a percolation sulfuric acid leaching of phosphogypsums with their preliminary washing with water is promising for obtaining high-quality gypsum raw materials.