DEFLUORINATION PROCESS

1,202,159. Defluorinating phosphates. INSTITUT GAZA. 18 June, 1968, No. 28985/68. Heading Cl A. Defluorinated phosphate is made by bubbling the combustion products of a fuel through a melt of natural phosphate, the fuel being burnt within the melt. Additives, e.g. silica, may be added to the melt to lower the melting temperature, and phosphorus containing compounds, e.g. phosphoric acid, potassium metaphosphate, may be added to increase the phosphorus content. The fuel may be liquid, e.g. petroleum products, or gaseous, e.g. natural gas. If insufficient water is produced by the combustion of the fuel extra water vapour is bubbled through the melt. Phosphates with a fluorine content of less than 0À2% and a P 2 O 5 content of 37-41% may be prepared by the process. In an example apatite concentrate containing 3-3.5% of fluorine is defluorinated at 1500-- 1580‹ C. using natural gas as a fuel to a fluorine content of less than 0À15%. Suitable apparatus for carrying out the process is described, and the products may be used in fertilizers and animal foodstuffs.