Evaluation of selective recovery of fine cassiterite from copper/zinc tailings: Comprehensive utilization of tailings resources

Abstract

In practical production, cassiterite flotation is typically conducted at the end of the mineral processing circuit, resulting in significant losses of fine-grained cassiterite to tailings, which not only wastes valuable resources but also poses environmental risks. This study aims to selectively recover fine cassiterite from copper/zinc tailings (CZT) using tert-butyl benzohydroxamic acid (TBHA) as a novel collector. Bench-scale flotation tests demonstrated that TBHA significantly outperformed conventional benzohydroxamic acid (BHA). At a collector dosage of 600 g/t, TBHA increased the tin grade from 0.81 % to 1.62 % and the recovery from 40.2 % to 49.8 %. The addition of zinc sulfate (600 g/t) further enhanced selectivity, raising the tin grade to 1.87 % and recovery to 65.8 %. Mechanistic studies, including adsorption measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and density functional theory (DFT) calculations, revealed that Zn²⁺ facilitated the adsorption of TBHA on the cassiterite surface by forming a stable five-membered chelate ring, rendering the (110) surface hydrophobic. These findings highlight the synergistic role of TBHA and Zn²⁺ in cassiterite flotation, offering a promising approach for the efficient recovery of fine cassiterite from tailings and contributing to the sustainable utilization of mineral resources.