Selective separation of smithsonite from quartz by using sodium polyaspartate as a depressant

This study introduced an easily degradable depressant, sodium polyaspartate (PASP), into the selective separation of smithsonite and Zn2+-activated quartz with sodium oleate (NaOL) as a collector. The flotation recovery of smithsonite significantly improved in the presence of PASP, and quartz and smithsonite were separated at pH 9–10. The flotation and depression mechanisms of smithsonite and quartz were studied by applying zeta potential measurements, total organic carbon analysis, scanning electron microscopy–energy spectrometry, and X-ray photoelectron spectroscopy. The results of various measurements indicated that PASP complexed with Zn2+ to cause the desorption of Zn2+ from the quartz surface, thus reducing the adsorption of NaOL on the quartz surface and depressing the flotation of quartz. However, although PASP could adsorb onto the smithsonite surface, it had little effect on the adsorption of NaOL. Therefore, PASP could be used as a quartz depressant in conventional smithsonite–quartz flotation circuits.