FREMGANGSMAATE VED EKSTRAHERING AV KROM, NIKKEL OG KOBOLT FRA LETERITTISKE NIKKEL- OG KOBOLTHOLDIGE MALMER

A method is provided for separating chromium from lateritic ore. The ore which generally also contains nickel and cobalt along with other metal values is leached with a strong sulfuric acid solution of about 10 to 30 normal concentration at an acid to ore ratio of at least 3:1 by weight. The leaching is carried out at a temperature of at least 100 DEG C ranging as high as about 300 DEG C at above atmospheric pressure. An oxidant, such as manganese dioxide, is preferably added to oxidize the chromium to the hexavalent state, the manganese dioxide, or its equivalent, being advantageous in improving the chromium yield at the lower end of the leaching temperature range.