Effects of the calcite on quartz flotation using the reagent scheme of starch/dodecylamine

Quartz and calcite are the representative gangue minerals exited in the hematite ores while the interactions between these gangue minerals are still unknown. The roles of calcite slimes on the quartz flotation using corn starch as the depressant and dodecylamine (DDA) as the collector were studied though micro-flotation tests, zeta potential measurements and DLVO theory calculations. The micro-flotation results showed that calcite significantly affected the quartz flotation. The flotation recovery of quartz largely reduced with the addition of fine calcite particles under the starch/DDA reagent scheme. The zeta potential results illustrated that there is an electro-steric attraction between quartz and calcite slimes, leading to the coating of calcite on quartz surface. The depressant starch could be absorbed onto the surface of coated calcite slimes and prevented the adsorption of DDA collector, thereby decreased the floatability of quartz. DLVO calculation confirmed the hetero-coagulation in the quartz-calcite slimes system.