Effective flotation separation of malachite from quartz with a selective collector: Collection ability, separation performance and adsorption mechanism

Abstract

In this study, we focused on the collecting features and sorption mechanism of stearyl diethanolamine (SDA) used as a novel collector towards the surfaces of quartz and malachite, to recover efficiently malachite from quartz. The flotation results demonstrated that DSA displayed an excellent collection performance for quartz but not for malachite. At pH 6.50, with 8 mg/L SDA, effectively recovering malachite from quartz was achieved by reverse flotation, in which 92.71 % of malachite was recovered and 91.91 % of quartz was removed, coupled with a high separation efficiency (SE) of 84.63 % and a high concentrate Cu grade of 52.52 %. Surface wettability studies suggested that SDA significantly improved the surface hydrophobicity of quartz but not malachite, as evidenced by the significantly increased contact angle of quartz (from 24.16° to 97.16°), which resulted in the excellent floatability of quartz. Adsorption amount detection results revealed that the adsorption density of SDA on quartz was much higher than that on malachite, namely 0.065 mg/g for quartz and 0.0049 mg/g for malachite, which enhanced the hydrophobicity of quartz. Zeta potential characterization and FTIR detection evidenced that apart from the strong electrostatic attraction interaction of the positively charged SDA+ with the quartz surface with negative charge, the strong adsorption of SDA onto quartz also depended much on the hydrogen bonding interaction between quartz’s Si-OH groups and SDA’s hydroxyl groups. Therefore, SDA can be regarded as a highly selective quartz collector to realize the effective recovery of malachite.