Accelerating the decarbonization of bio–oxidation residues from carboniferous high arsenic sulfide refractory gold ores via suspension oxidation roasting for exceptional gold leaching efficiency

Abstract

To address the low gold recovery following bio–oxidation of carboniferous high–arsenic sulfide refractory gold ores, this study proposes the application of suspension oxidation roasting as a secondary treatment strategy aimed at disrupting carbonaceous encapsulation and structural constraints, thus facilitating gold exposure and improving leaching efficiency. Thermal analysis employing TG–FTIR–GC–MS indicated that efficient decarbonization predominantly occurs within the temperature range of 550 °C to 650 °C, while arsenic volatilization remains negligible. XRD analysis further verified that pyrite and jarosite undergo thermal decomposition within this range, leading to the formation of stable iron oxides capable of immobilizing sulfur and arsenic. SEM–EDS and BET analyses demonstrated that the roasted residues exhibit a honeycomb–like porous morphology, which markedly increases surface reactivity and facilitates leachant infiltration. Under the optimized condition of 550 °C for 45 min, the carbonaceous removal efficiency reached 99.5 %, arsenic fixation exceeded 95.0 % and the gold leaching rate was significantly enhanced from 15.4 % to 80.2 %. These findings confirm the effectiveness of suspension oxidation roasting in enhancing gold recovery from bio–oxidation residues and provide both theoretical insight and technical support for the efficient treatment of carbonaceous high–arsenic sulfide refractory gold ores.