Fluorine Recycle in Phosphoric Acid Plants with the Di-Hydrate Process

The fluorine recycle in the manufacture of superphosphate is an original Montedison process and was first presented at the ISMA Technical Conference in The Hague in 1976. Studies were carried out in the Fertilizer Research Center in Porto Marghera and the know-how was applied by Agrimont in the revamping of numerous superphosphate plants and in the construction of new plants in Italy and abroad. Studies were continued in order to extend the technique of the fluorine recycling to the phosphoric acid processing. The first mention of this was given at the IFA/CNCCC Technical Conference in Peking in 1983. The process chemistry was examined thoroughly and the basic operations were developed and improved in the utilization of several phosphate rocks. The main advantages of the process are: - the solution of various ecological problems due to the total re-utilization of the wastes in the production cycle; - reduction in the consumption of sulphuric acid to attack the phosphate rocks; - improvement of the process efficiency. The fluorine recycling process was Marghera in 1977 and in the ISAF plant at Gela in 1981.