Recovery of chromium values

Claim 1

In the recovery of chromium values from a chromium bearing source, the improved method which comprises the steps of: a. forming a mixture of said chromium bearing source, sulfuric acid and a compound containing manganese in at least a +4 valence state in a weight ratio of from about 1:1:1 to about 1:2:10 chromium bearing source, manganese compound and sulfuric acid, respectively; b. roasting said mixture at a temperature of from about 200° to about 500° C for a sufficient time to remove the major portion of its water content and excess sulfuric acid; c. leaching the resultant damp pulp with water at a temperature of from about 25° to about 95° C; d. filtering the leach solution to separate undissolved solids from pregnant leach liquor containing dissolved manganese compound and chromium ions in a +3 valence state; e. subjecting the pregnant leach liquor to a neutralization-oxidation treatment with an additional amount of said chromium bearing source and manganese compound to oxidize said chromium ions to a +6 valence state; and f. thereafter selectively extracting chromium from the thus treated pregnant leach liquor.