MINERAL PROCESSING BEHAVIORS OF CHROMITE CONTAINED IN LATERITE - FUNDAMENTAL STUDIES ON MINERAL PROCESSING OF CHROMITES (2ND REPORT).

Degree of separation, grindability, zeta-potential, floatability, and magnetic property of chromite in the lateritic nickel-leached residue of Nonoc refinery (Philippines) were investigated. The results are summarized as follows: A considerable amount of magnetite-like iron oxide is contained in the leach residue. Accordingly, the most part of chromite coexists with the iron oxide. The degree of separation of chromite in oversize fraction of 37 mu m is 58%. From the measurement of zeta-potentials with various pH, it can be said that the zero point of charge (ZPC) of chromite is pH 7. 4. Below the ZPC chromite is positively charged, so it shows a high floatability by the addition of anionic sodium dodecyl-sulfate. Above the ZPC where chromite is negatively charged, it shows an excellent flotation recovery by the addition of cationic dodecylammonium chloride. Sodium oleate gives the maximum floatability at a pH of approximately 8. The optimum flotation size of chromite ranges from 60 to 100 mu m, and the floatability of it decreases with increase or decrease in particle size.