Phosphate rock may be new rare-earth source

Rare earths are available for recovery from wet-process phosphoric acid production, suggest Zalman S. Altschuler, Sol Berman, and Frank Cuttitta of the U.S. Geological Survey, Washington, D.C. At a meeting of the Society of Mining Engineers of AIME in Tampa, Fla., Mr. Altschuler estimated that the magnitude of such potential extraction of rare-earth metals is sufficient to stimulate industrial research. The rare earths occur in solid solution in the structure of apatite, the principal mineral in phosphate rock. This occurrence is a result of diadochic (coupled) subsitution, in which the replacement of divalent calcium by trivalent rare earths is electrostatically balanced by the replacement of another calcium ion by a sodium ion, or by the substitution of the silicate radical for the phosphate radical. Although the rare earths so substituted constitute only 0.01 to 0.1% of the apatite, the value of the metal content becomes appreciable because of the enormous quantities of rock which are ...