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Evaluation of Potential Commercial Processes for the Production of Sulfuric Acid from Phosphogypsum


Phosphogypsum is a synthetic by-product created during the commercial manufacture of phosphoric acid by the wet process. The synthetic phosphogypsum retains the basic chemical and physical properties of natural gypsum and can be substituted for natural gypsum in the manufacture of a variety of commercial products. The commercial incentives which justify the exploitation of by-product phosphogypsum in nations which lack domestic gypsum sources and seek to avoid expensive imports are absent in Florida. As a result, phosphoric acid producers in Florida consider phosphogypsum a process waste requiring permanent disposal. Approximately 30 million tons are added each year to the more than 300 million tons of phosphogypsum currently stockpiled in Florida. At that rate, the volume of waste gypsum stored in Florida will triple by the year 2000. The reduction of gypsum disposal requirements through commercial exploitation of by-product phosphogypsum has been assigned a high priority by the Florida Institute of Phosphate Research (FIPR). This report documents the technical feasibility of substituting synthetic phosphogypsum for the natural gypsum used in an experimental process which recovers the commercial sulfur values liberated by the thermal decomposition of natural gypsum.