Silicate covering layer on pyrite surface in the presence of siliconcatechol complex for acid mine drainage prevention

Abstract

In this paper, prevention of pyrite oxidation by carrier microencapsulation (CME) was investigated. A possible layer structure was suggested following analysis with electrochemical and surface analysis techniques. Electrochemical study of treated pyrite samples showed that treatment with siliconcatechol (Si-Cat) for 6 h at an initial pH of 9.5 gave the best barrier properties and suppression of the samples. Scanning electron microscopy with energy-dispersive X-ray, and Fourier transform infrared (FTIR) analyses confirmed the presence of a silicate layer on the surface of treated pyrite. X-ray photoelectron spectroscopy indicated that the coating layers on the treated pyrite samples consisted of a network of Fe-O-Si and Si-O-Si units bonded to the surface of pyrite. The Si-O-C asymmetric stretching mode was also observed in FTIR spectra. Detailed spectroscopic analyses confirmed the formation of a silicate polymer on a silicaquinone layer, which resulted in the effective suppression effect shown by Si-Cat-treated pyrite at increasing pH.