Exploring the connection between elemental sulphur and sulphide minerals during Stage A conditions - A Design of Experiments Investigation

Under certain conditions, sulphide minerals are susceptible to a phenomenon called Self-Heating (SH), where a material heats up without an external heat source. Self-heating is an exothermic oxidation reaction that occurs in three distinct temperature Stages, namely Stage A (room temperature to 100 degrees C), Stage B (100 degrees C - 350 degrees C), and Stage C (above 350 degrees C). New studies have shown that sulphide self-heating reactions are heavily influenced by the interaction between elemental sulphur and pyrrhotite ore during Stage A conditions. The aim of this study was to employ a Design of Experiments (DOE) method to investigate how differing Stage A conditioning parameters influence the interaction between elemental sulphur and pyrrhotite ore, and their effect on Self-Heating Capacity (SHC). The 5 main factors used to explore the differing Stage A conditions were elemental sulphur content, conditioning time, oxygen content, moisture content, and temperature. The optimum conditioning parameters that led to the highest degree of Self-Heating were calculated to be: 8.5 hr, 95 degrees C, 80 ml air/min, 10 wt% moisture, and 3 wt% elemental sulphur.