Selective flotation of scheelite from calcite: A novel reagent scheme

Sodium oleate (NaOl) has been widely used as a collector for the scheelite flotation. However, low selectivity of NaOl and large amount of sodium silicate (SS) needed remain tough problems. In this study, octyl hydroxamic acid (HXMA-8) was used as an associate collector with NaOl in scheelite flotation. The flotation tests showed that a novel reagent scheme, i.e., a lower dosage of SS (300 mg/L) and mixed collectors of HXMA-8 + NaOl (total concentration 4.5 x 10(-4) mol/L, preferred mass ratio of 1:2) achieved the selective separation of scheelite from calcite. Zeta potential measurements indicated that the depressant, SS, adsorbed more strongly on calcite surface than on scheelite surface. HXMA-8 adsorbed significantly on scheelite surface either in the absence or presence of SS by chemical bonding between oxygens of HXMA-8 and surface metal ions. NaOl also adsorbed on both mineral surfaces by chemisorption, but the adsorption on calcite surface was influenced adversely by the presence of SS. (C) 2016 Elsevier B.V. All rights reserved.