Interfacial phenomena in the sulfur–polytetrafluoroethylene system under hydrothermal conditions

Sulfur occlusion of pyrite particles during 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, which is comparable to published values in the pyrite–sulfur system.