Optimizing the SART process: a critical assessment of its design criteria

Abstract

The SART (Sulfidization, Acidification, Recycling and Thickening) process has been successfully installed to recover cyanide and copper in seven worldwide gold cyanidation plants in the last 15 years. This technology has allowed the extraction of gold ores containing high grades of cyanide-soluble copper. However, this process has high capital costs and requires rigorous operational control, which have limited the installation of this process in the last 5 years. These drawbacks have not been overcome despite the successful operation of the SART process worldwide, limiting the interest of gold mining in performing new studies to support new developments in order to optimize plant design. In this framework, this study attempts to give a critical assessment of the design criteria of the SART process, based on experimental work focused on optimizing the SART process, challenging some conventional criteria typically considered in the design of SART plants. Thus, this study involves (i) a kinetic characterization, which allows determining the optimal residence time in the sulfidization reactor to be determined, (ii) oxidation/reduction potential (ORP) measurements with respect to the conversion, which suggest an adequate control logic that maximizes metal recovery in the sulfidization reactor, and finally (iii) settling tests to propose a correct criterion for recycling the settled slurry into the sulfidization reactor. These results show that it is possible to reduce the residence time in the sulfidization reactor by up to 1 min. Furthermore, it was established that the precipitation performance depends on the ORP value. Therefore, a control logic as a function of this parameter could be implemented. Finally, the settling results pave the way for establishing a new criterion for recycling the underfiow slurry from the thickener to the sulfidization reactor, based on the copper concentration in the feed solution. Hence, this study proposes new design criteria for future SART plants, saving capital costs and optimizing the metal recovery control.