Metals such as lithium are recovered from mixtures of oxides and silicates, such as clays, by selective chlorination with h2o-hcl vapors at high temperature. The optimum concentration of hcl in the mixture is 20-35 pct, and the preferred chlorination temperature is 500 deg-800 deg c; the resulting chlorides are leached with water at 20 deg-80 deg c. Thus, clay containing al 1.6, Si 19.5, Mg 7, ca 12.7, and li 0.5 pct was chlorinated at 700 deg c with a h2o vapor- 20 pct gaseous hcl mixture for 30 min. The product was leached with water at 80 deg c for 5 min, and the leach solution contained 80 pct of the li, with only 10 pct of the ca and 0.01 pct of the mg.
U.S. Pat. 4,307,066, Dec. 22, 1981; Chem. Abstr. 94:87,874A