Interfacial phenomena in the sulfur-polytetrafluoroethylene system under hydrothermal conditions

Sulfur occlusion of pyrite particles during the oxidative pressure leaching of mineral sulfide concentrates at temperatures below 160°C has a deleterious effect on pyrite oxidation kinetics. Existing techniques in mitigating sulfur occlusion involve the use of surfactants or operation at temperatures above 160°C which are a burden to the process economy. This study looks at the suitability of polytetrafluoroethylene (PTFE) to act as a solid sorbent for the liquid sulfur generated during the pressure leach process. The suitability of PTFE as a solid sorbent was determined by comparing interfacial phenomena in the corresponding sulfur-PTFE-leach and sulfur-mineral-leach systems. The work of adhesion in a sulfur-PTFE system was calculated using the interfacial tension and contact angle measured in the relevant sulfur-PTFE system. The conclusion of this study is that PTFE may make a suitable solid sorbent for sulfur in a leach solution without the use of surfactants.