Characterization of the dust explosibility of the iron sulphides: iron(II) sulphide and iron disulphide

Frequent incidents of secondary sulphide dust explosions in underground mines have prompted the mining industry to adopt preventive measures and also obtain a better understanding of these materials. Among the various sulphides, the iron sulphides: FeS and FeS{dollar}sb2{dollar} are the most reactive, and are also present in abundant amounts. They are prone to spontaneous combustion in the presence of an oxidation source. The reactions are exothermic and there is thus the hazard of mine fires and dust explosions. This study was therefore aimed at a comprehensive investigation of the iron sulphides.; The work was divided into three parts to meet the above-mentioned objective. In the first stage, the feasibility of thermogravimetry was investigated for applications to dust cloud ignition and explosions. Using isothermal and non-isothermal methods and high temperature and heating rates to simulate explosions, the kinetic parameters of activation energy (E) and frequency factor (A) were determined for the iron sulphides. Such basic kinetic data are currently not available in the literature. They can be used for developing mathematical models for dust explosions, and other end-applications.; In the second stage, the explosibility characteristics of pure and mine samples of the iron sulphides were investigated. Using mine samples of pyrite and pyrrhotite and pure samples of FeS and Fes{dollar}sb2{dollar}, the maximum pressure rise, P{dollar}rmsb{lcub}max{rcub}{dollar}, the maximum rate of pressure rise, (dP/dt){dollar}rmsb{lcub}max{rcub}{dollar}, and the minimum explosible concentration, MEC, were determined in the 20-L Siwek Chamber. The critical mass mean diameter for explosibility (D{dollar}rmsb{lcub}W,critical{rcub}{dollar}) was established for the mine samples of pyrite and pyrrhotite using fairly narrow size distributions. It was observed that pyrite is more explosible in comparison to pyrrhotite. The reaction mechanisms that hold were also examined. These results are thus of fundamental and practical value in the practice of loss prevention.; In the third stage, the minimum ignition temperature (MIT) of the materials mentioned above were measured in the BAM oven developed by Bundesanstalt fur Materialprufung. The results once again showed that pyrite is more reactive in comparison to pyrrhotite. The test results were validated using a dense cloud ignition model. Also using the test result, reaction mechanisms that predominate were investigated.; In all three studies it was consistently observed that heterogeneous reaction mechanisms hold for the iron sulphides. Combined with the other conclusions, this helped in gaining a better understanding of the explosibility of the iron sulphides.