The thermal decomposition of pyrite

A study has been made of the kinetics of the thermal decomposition of pyrite to pyrrhotite and sulphur in a dynamic argon atmosphere. The reaction was followed (a) by the rate of loss of weight as indicated by the extension of a quartz spring and (b) by the rate of progression of the pyriteipyrrhotite interface into a polycrystalline compressed pellet. The temperature coefficient of the reaction was found to be 69.5 ± 5.9, 64. 7 +- 3.3 and 66.9 ± 5.1 kcal. mole- 1 when the results were processed in three different ways. The pyriteipyrrhotite interface was found to progress at a linear rate into the pellet and equations were derived to express the variation of reaction rate with temperature. Attempts to study the early nucleation stage of the decomposition, using mineral crystals, proved abortive.