Flotation separation of cassiterite from calcite and quartz via novel collector sodium monododecyl phosphate

Abstract

Due to the similarities in surface properties between cassiterite and oxides gangue minerals, achieving efficient flotation separation with conventional collectors presents considerable challenges. In this study, sodium monododecyl phosphate (SMP) was employed as a novel collector for the first time to separate cassiterite from calcite and quartz. The flotation test results showed that the high-efficiency separation of cassiterite from the two gangue minerals could be achieved by using SMP as a collector without adding depressants. When pH was 10 and SMP dosage was 250 mg/L, the tin grade and the recovery of concentrate, which was acquired by artificial mixed minerals experiment were 56 % and 87 %, respectively. Moreover, the selective collection mechanism of SMP onto the three minerals was also elucidated by contact angle detection, zeta potential measurement, adsorption test, and FTIR analysis, which found that SMP is chemisorption on the surfaces of cassiterite rather than the calcite and quartz surface, and the adsorption strength between SMP and cassiterite is much stronger than that of calcite and quartz, so the hydrophobicity of cassiterite is improved more remarkably than the other two gangue minerals. In addition, XPS analysis and DFT calculation further confirmed that SMP chemisorbs on the cassiterite surface through chelation between the phosphate groups in the reagent molecules and tin atoms on the cassiterite surface, forming a five-membered ring structure. Therefore, this study presents a viable strategy for the development of novel high-efficiency collectors for cassiterite flotation.