Abstract
The design and Engineering of hydro and pyro-metallurgical process circuits using new technologies for the extraction and disposal of materials is challenging and driven by numerous inputs including bench test work outcomes, pilot-level demonstrations, process simulations, operability requirements, personal experience, and capital constraints.
This paper discusses these issues in the Canadian/ European context and covers the extraction of gold from an arsenopyrite gold concentrate. A systematic study was performed for the project aimed at using DST’s Glasslock arsenic removal and stabilization process to increase the profitability of a mining operation that produces lead, zinc, and gold-bearing arsenopyrite concentrates.
The ore body is refractory to direct conventional cyanidation and requires suited extraction approaches to reduce the environmental liabilities associated with arsenic and maximize the payable gold revenue. The gold leaching results using DST’s CLEVR process have also shown that a gold extraction yield of 71% could be achieved on the calcine as opposed to a 53% yield when using cyanidation.
Since the gold concentrate is facing market penalties due to high arsenic levels, the added value proposed by DST is the Glasslock process to remove and stabilize the arsenic at costs inferior to market penalties. Moreover, the results of the test program demonstrated the feasibility of sequestering arsenic trioxide (As2O3) into a stable arsenical glass. A glass containing 16.3% arsenic was produced and successfully met the EU 12457 norms and protocol for stability.
Particular focus is placed on some practical aspects of DST process design and engineering and the impact that these decisions can have on the operation.