The Effect of Sulphide Mixtures on Self-Heating

Under certain conditions of air and moisture, sulphide materials can spontaneously heat or self-heat The reaction mechanisms of self-heating are not well understood Most previous work has Involved pyrrhotite because it is the most reactive sulphide The current work investigates the self-heating behaviour of sulphide mixtures composed of sulphides other than pyrrhotite The four studied sulphides were pyrite, chalcopyrite, sphalerite and galena The rest-potential was measured for each Binary mixtures formed as a l I weight ratio were pyrite-galena, chalcopyrite-galena, pyrite-chalcopyrite and chalcopyrite-sphalerite The four sulphides and the binary mixtures were subjected to standard self-heating tests The four individual sulphides did not self-heat However, mixtures of pyrite-galena and chalcopyrite-galena with rest-potential difference (Delta E) > 0 3 volts did self-heat while the mixtures of pyrite-chalcopyrite and chalcopyrite-sphalerite with rest-potential differences (Delta E) <= 0 1 volts did not self-heat The results demonstrate that when certain non self-heating sulphides are combined they can self-heat A possible explanation based on galvanic interaction and formation of hydrogen sulphide as an intermediate product is discussed