Identification of elements hindering gold leaching from gold-bearing dust and selection of gold extraction process

Abstract

The gold-bearing dust generated during the roasting process of refractory gold concentrates is valuable as a secondary gold resource. In this study, the effects of different pre-treatment methods on the removal of harmful elements and gold extraction from gold-bearing dust by cyanidation after pre-treatment were studied based on mineralogical analysis. The results showed that the dust belonged to refractory gold ore category, and the detrimental effects of arsenic, carbon and iron on gold extraction could be responsible for the low gold extraction. The removal efficiencies of arsenic and carbon were 99.7 and 60.6%, respectively, at a NaOH concentration of 6 mol L−1; moreover, gold extraction was 58.9% and increased by only 4.60% compared to direct cyanidation. The removal efficiencies of iron, arsenic, and carbon were 33.7, 80.4, and 12.6% at a 15 wt% H2SO4 concentration, respectively, and gold extraction reached 80.4%. After roasting at 650 °C with an airflow rate of 0.2 m3 h−1 for 4 h, the removal efficiencies of arsenic and carbon were 54.7 and 95.0%, respectively, and gold extraction reached 84.5%. Through 6 mol L−1 NaOH leaching after roasting, the removal efficiencies of arsenic and carbon were 99.5 and 95.5%, respectively, and gold extraction reached 86.1%. Through 50 wt% H2SO4 leaching after roasting, the removal efficiencies of iron, arsenic, and carbon were 99.5, 99.6, and 99.0%, respectively, and gold extraction reached 95.5%. These findings indicated that carbon had the greatest influence on gold leaching from the dust, followed by iron and arsenic. Through the comparison of different gold leaching processes, a proper process for gold extraction from the dust was developed. Under the most suitable condition, gold extraction improved by 41.2% compared to that of direct cyanidation.