Degradation of various thiol collectors in simulated and real mineral processing wastewater of sulfide ore in heterogeneous modified manganese slag/PMS system

Abstract

Residual flotation reagents (FRs) in mineral processing wastewater (MPW) cause serious organic pollution and difficult to discharge or recycle of MPW. In this study, the degradation of 100 mg/L of FRs (butyl xanthate (BX), diethyl dithiocarbamate (DDTC), ester-200 (Z-200) and butyl amine (BA)) commonly used for metal sulfide ore flotation were investigated by heterogeneous advanced oxidation process (AOPs) adopting peroxymonosulfate (PMS) as oxidants and modified manganese slag as metal-base catalyst (MS-N3H). The results showed MS-N3H/PMS system had higher degradation capacity than other reports, by which 100% of DDTC and 97.3% of BX could be degraded in 10 min, also 93.2% of Z-200 and 85.6% of BA were degraded in 30 min, respectively. The differential behaviours in degradation of thiol collectors (TCs) were correlated to their molecule structures and affected by their HMO index. However, the good water solubility of BX made it as the most degradable reagents in competitive system. The catalytic reactions of Z-200 and BA were pH-dependent processes which were dominated by the PMS ionization and base activation. Inorganic ions had little effects on reactions except for SiO32−, but the negative effect could be alleviated by the integrated process. Higher mineralization degrees of C, S and N elements indicated that TCs and their by-products were removed by the MS-N3H/PMS with higher degradation rates. Further, the catalyst showed superior regeneration ability and the system could be effectively used in real MPW treatment with relatively high removal efficiency of total organic carbon (TOC).