Production of magnesium phosphate from apatite and carnallite. 1. Chemistry and Mineralogy

Magnesium phosphate was produced from Oron phosphate and carnallite. Chemical and mineralogical aspects were studied as a function of reaction temperatures, F/P ratios, Mg/Ca ratios, reaction times, and grinding the phosphate. Although two reaction mechanisms are suggested in the literature, it appears that no clear-cut conclusion can be reached and that neither explains all the observed facts. The most likely mechanism seems to be one in which the first step is the formation of chlorapatite and MgF2. The chlorapatite reacts to give magnesium phosphate which reacts with MgF2 to form wagnerite. Magnesium phosphate and wagnerite are in equilibrium; the higher the temperature, the higher is the magnesium phosphate yield in the product.