Mineralogical, chemical and textural characters of ore strongly affect the efficiency of chromite sand concentration with gravity devices (i.e. spirals and shaking tables). Such parameters were studied in chromite ores where gravity enrichment of sands occurs or is planned in Albania and Greece. Chromite alteration in metamorphic conditions can lead to redistribution of Cr_2O_3 from chromite to silicates. Such redistribution was studied on the Vavdos chromite deposit (Greece) where more than 3 wt% Cr_2O_3 can be found in silicates. The effect of the redistribution is to lower the efficiency of gravity plants as Cr_2O_3contained in silicate phases will be preferentially discharged into the tailing during enrichment. Textures of chromite ore affect the degree of liberation of chromite after crushing and consequently the efficiency of the plant. At the Bulqiza gravity enrichment plant (Albania) a cost effective technique was tested to determine liberation through grain counting and its correlation with plant efficiency was evaluated.
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