Recovery of Cr.sub.2 O.sub.3 from a chromium bearing solution

A method for recovering high purity Cr.sub.2 O.sub.3 from chromium ore which comprises:

• (i) roasting in a gaseous oxidizing environment a mixture of chromium ore with Na.sub.2 CO.sub.3 and CaO at a temperature in the range of about 600.degree. C. to 1100.degree. C. for from about 0.5 to 6 hours, the amount of Na.sub.2 CO.sub.3 being that which provides from about 1.4 to 4.2 pounds of Na.sub.2 CO.sub.3 per pound of Cr.sub.2 O.sub.3 in the ore and the amount of CaO being that which provides from about 0.6 to 1 pound of CaO per pound of Cr.sub.2 O.sub.3 in the ore;
• (ii) water leaching roasted material obtained in step (i) at a temperature of from about 5.degree. C. to the boiling point of water for from about 5 minutes to 5 hours;
• (iii) adding acid to the leach liquor obtained in step (ii) to provide a pH of from about 3 to 9.5 to cause precipitation of aluminum impurities and separating said impurities from the leach liquor;
• (iv) adding acid to the leach liquor to provide a pH of about 1 to 2;
• (v) contacting the acidified leach liquor obtained in step (iv) with a tertiary amine dissolved in an organic solvent essentially free of isodecanol to inhibit the formation of emulsion, to recover chromium values from the acidified leach liquor in a chromium containing organic liquid phase;
• (vi) treating the chromium containing organic phase with a water solution of NH.sub.4 OH to obtain a solution of (NH.sub.4).sub.2 CrO.sub.4 ;
• (vii) subjecting the solution of (NH.sub.4).sub.2 CrO.sub.4 to evaporation to provide a solid chromium-bearing material;
• and
• (viii) igniting the solid chromium-bearing material to obtain Cr.sub.2 O.sub.3.