Recycling of gold mining reject from Amesmessa mine as ceramic raw material: microstructure and mechanical properties.

The extraction of gold ore generates rejects called gold mining reject (GMR). This reject is considered a major environmental problem for the mining industry. In Amesmessa mine (Hoggar, Algeria), where mining have been carried out for over 15 years, about 2 million tons of mill tailings has been accumulated each year. The aim of this work is to study the reuse of GMR as raw material in ceramic field and its effect on microstructure, color, and mechanical and chemical properties. During investigation, the results show that GMR is mainly composed of quartz, hematite, pyrite, and dolomite. During sintering, mullite, quartz, anatase, and rutile were the mineralogical phases which composed the ceramic samples. As the temperature rises at 1200 °C, peaks of mullite increased, beside rutile and quartz phases. When 30 wt% of the reject was added, the crystalline phases as quartz and mullite diminished, giving rise to the glassy phase formation that is promoted by metal oxides playing a role as fluxing agents. Elastic property as Young's modulus of the samples increased from 09.35 to 15.93 GPa and from 19.66 to 60.94 GPa at 1100 °C and 1200 °C respectively. The environmental study of the incorporation of GMR in ceramic matrix, rich in heavy metals (Fe, Zn, Ni), was evaluated by leaching tests of the fired products. The results indicated a successful immobilization of the heavy metals. These results suggested the use of gold mining reject in the ceramic field, as a substituent of feldspar, and might be an alternative and reliable method for the disposal of this reject.