Selective flocculation and recovery of chrome from plants limes using starch and sodium oleate as flocculants

plant in the north west province of South Africa was conducted using raw corn starch and sodium oleate as flocculants and sodium silicate a dispersant was applied on. Limited work has been reported on the flocculation of non-synthetic chrome slimes. The results showed that a slime sample with a chrome (Cr 2 O 3 ) head grade of 22.92% was upgraded to a maximum concentrate grade of 42.55% at a sodium oleate dosage of 88 g/ton slurry , a sodium silicate dosage of 44 g/ton slurry , 39.61% at a starch dosage of 106 g/ton slurry and sodium silicate dosage of 62 g/ton slurry . The corresponding recoveries using sodium oleate as a flocculent were between 80–89% and 73–79% for starch. Sodium oleate showed a better performance than starch in terms of both grade and recovery. Decantation washing tests showed that the chrome (Cr 2 O 3 ) grade of the concentrate can be further increased to above 44%. These results are very encouraging as they indicate that selective floccula - tion can achieve satisfactory upgrade ratios and recovery when processing chrome ultrafine or slime material.