Specifically Adsorbed Ions in the Reverse Cationic Flotation of Iron Ore

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Although extensive research has been conducted on the effect of water chemistry in flotation, no single study exists which describes the effect of calcium and magnesium on the adsorption of starch onto the hematite in iron ore flotation. In this work flotation, entrainment, zeta potential, and settling tests were performed to determine the differing impact of calcium and magnesium in iron ore flotation. Results showed that magnesium is more detrimental to the flotation process at far lower concentrations than calcium. Performing flotation with 45 ppm of calcium resulted in a comparable impact on the process as performing flotation with 7 ppm of magnesium. While calcium promotes the adsorption of starch onto the hematite and reduces entrainment, past an optimal dosage magnesium is promoting the adsorption of starch to everything in solution causing low grades and recoveries. It was found that the starch adsorption onto the hematite is strongly impacted by the presence of magnesium, suggesting that starch is collecting the magnesium and self-flocculating prior to adsorption onto the hematite. Thus, the presence of magnesium can significantly reduce the flotation performance far more than what would be expected from calcium.

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Mineral Processing and Extractive Metallurgy Review