Cleaner process: Efficacy of chlorine in the recycling of gold from gold-containing tailings

To develop a cleaner production technology for the construction of secondary resources, this study researched the best chlorine source for the sustainable recovery of gold from gold-bearing tailings via chlorination heat treatment. A thermal analysis of different chlorine sources, NaCl, MgCl2, KCl and CaCl2, was performed via Factsage 7.2 (thermodynamic software) and thermogravimetric analysis differential scanning calorimetry. The results showed that CaCl2 has a stronger chlorine supply capacity during the chlorination roasting process. Moreover, the positioning of CaCl2 during the heat treatment was investigated by studying the gold recovery rate and chlorine removal rate at different temperatures. Meanwhile, using an electronic probe microanalysis and X-ray diffraction, the key mechanism in the process of chlorinated gold recovery was analyzed. It was found that as long as it was an alkaline chlorine source, it damaged the gangue structure. However, the trend of the slagging reaction with CaCl2 was more intense. Under the best conditions, roasting tailings with 5 wt% CaCl2 at 1273 K yielded an 85.99 wt% gold recovery and 82.84 wt% chlorine removal. Thus, the harmless management of roasting tailings under the premise of effective gold recovery can be achieved. This research promotes the industrialization of secondary resources via the chlorinated roasting clean treatment. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the use of CaCl2 as a chlorine source for the sustainable recovery of gold from gold-bearing tailings via chlorination heat treatment, demonstrating its superior chlorine supply capacity. Understanding the mechanism of gold recovery and chlorine removal at different temperatures, the research indicated that roasting tailings with 5 wt% CaCl2 at 1273 K yielded the best results, with an 85.99 wt% gold recovery and 82.84 wt% chlorine removal. Overall, this research contributes to the industrialization of secondary resources through clean treatment processes.