Two-wavelength pyrometry study of the combustion of sulfide minerals: Part I. Apparatus and general observations

Abstract

The temperatures of individual sulfide particles combusting in air have been measured with a two-wavelength radiation pyrometer. The pyrometer design allowed the temperature of the combusting particles to be measured for 15 to 30 ms; and the response of the system was sufficient to determine the heating rates of particles during reaction. The combustion of galena, pyrite, and pyrrhotite, in air, at 1130 K was investigated. The different minerals produced distinct combustion pulses which were recorded repeatedly. Galena particles reacted in air at a relatively constant apparent temperature of between 1400 and 1700 K. Reaction product fume was observed trailing behind the combusting particles. The pyrometer pulses recorded during the combustion of pyrite and pyrrhotite particles were similar; however, pyrite tended to ignite more rapidly than pyrrhotite. During combustion in air, the temperature of the iron sulfide particles increased at a constant rate up to a maximum of 2200 to 2600 K after which rapid cooling occurred; a sudden rise in combustion energy at peak temperature was likely due to an merease in the particle size resulting from the formation of cenospheres.