Selective separation of scheelite from calcite using tartaric acid and Pb-BHA complexes

The calcite content severely restricts the flotation of scheelite in tungsten ores. Previous researches have proven the surface transformation between fluorite and calcite could promote the selective flotation of scheelite from other calcium-containing minerals when the lead complexes of benzohydroxamic acid (Pb-BHA) were employed as collector. However, given the increasing content of calcite in tungsten ores, it's hard to obtain qualified scheelite concentrate with only Pb-BHA, so developing highly selective depressants to combine with Pb-BHA is necessary. Here, tartaric acid (TA) and Pb-BHA were used for the flotation of scheelite from calcite. Current flotation results showed that this reagent scheme (TA and Pb-BHA) could effectively separate scheelite from calcite. The zeta potential measurements and X-ray photoelectron spectroscopy analysis revealed the adsorption of TA on the calcite surface is much stronger than that on the scheelite surface. Crystal chemistry analysis demonstrated that the distance between the TA functional groups and calcium distance on the calcite surface matched better than that on the scheelite surface, which may directly contribute to the high selectivity of TA. In addition, zeta potential and infrared spectrometric analysis demonstrated that the Pb-BHA adsorption on the calcite surface was significantly impacted by TA, but Pb-BHA still could be intensively absorbed on the scheelite surface after interaction with TA.