Sulfi disation of Ilmenite Concentrates Contaminated with Chrome Spinels – A New Approach to Impurity Separation

摘要

High temperature roasting studies on chrome-spinel contaminated ilmenite concentrates showedrnthat sulfur, introduced through a sulfi dising roast treatment, selectively reacted with the chromiumrnin the spinels. The roast treatments were carried out in a laboratory scale rotating drum kiln using arnstandard Becher-style heating profi le (10 h, 1075℃), char as the reductant, and variable amounts ofrnadded elemental sulfur (0 - 3 wt per cent).rnAfter roasting, bronze-coloured grains were visible representing chrome-spinels that hadrnundergone selective sulfi disation. SEM imaging of the products showed that sulfur was preferentiallyrnconcentrated in ～15 μm thick rims fully enclosing the chrome-spinel grains. The sulfur-rich rimsrnbecame a sink for manganese (Mn) from the ilmenite resulting in the rims being rich in Cr-Mn-Fesulfirndes. Quantitative electron probe microanalysis of phases present within the rims identifi ed twornsulfi de phases. The fi rst sulfur-phase (S-phase) was low in Mn (1 - 3 wt per cent) and high in Fe, Crrnand S, while the second S-phase was considerably higher in Mn (30 - 35 wt per cent Mn) and lowerrnin Fe and Cr.rnThe dramatic change in the composition of the chrome spinels after sulfi disation is likely tornsignifi cantly alter their physical properties (eg hydrophobicity, conductivity, etc). This should makerntheir physical separation from the ilmenite potentially easier than roasting/magnetic separationrnmethods.