Dry magnetic separation of olivine sand
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Norwegian University of Science and Technology
Publication date: 2011-06-01
Physicochem. Probl. Miner. Process. 2011;47(1):213–228
This paper investigates the potential for using dry magnetic separation to reduce the chromium content of a dried high quality olivine sand product in order to meet with anticipated future quality demands. The original feed contained 0.28-0.29% Cr2O3 of which approximately one third occurred as chromite and two thirds as chlorite. Two stage Permroll separation (at 0.50 T (max) and 0.92 T (max)) produced a concentrated product containing 0.13% Cr2O3 at a product recovery of 85.28%, thus reducing the chromium content by 55%. Some 80% of this reduction was achieved as a result of the first separation stage where chromite reported to the magnetic tailings at a recovery close to 100%. The chromium remaining in the concentrated product must be attributed to chlorite. Leachates obtained from leaching tests performed on the feed and the products were characterised by very low chromium concentrations, and the results suggest that chromium is more easily released from chlorite than chromite. This study shows that dry magnetic separation could be considered when a reduction of the chromium content of dried high quality olivine sand products is required.