Method for preparation of defluorinated phosphate

A method for reducing the fluorine content of phosphate rock comprising:

• blending the rock with water and an amount of phosphoric acid and a sodium defluorinating reagent sufficient to give 5 to 9 percent Na.sub.2 O based on the weight of the rock and a mole ratio of CaO plus Na.sub.2 O to P.sub.2 O.sub.5 of about 3;
• introducing the blend into a fluidized bed calcination apparatus having at least a first and second reaction zone, each of said zones being at a temperature above about 1050.degree. C.;
• calcining the blend in the first zone in the presence of water vapor or optionally air and water vapor to remove a major proportion of the fluorine from the blend, and
• further calcining the blend in the subsequent zone or zones without substantial cooling of the blend between the first zone and the subsequent zone, said further calcining being carried out in the presence of water vapor and in an atmosphere containing air added in an amount in excess of that required for combustion and in excess, on a percentage basis, of that present in the first zone, said amount being sufficient to reduce the fluorine content of the blend to a value of less than about 0.18 weight percent while maintaining the phosphorus to fluorine weight ratio in excess of about 100.