Study On The Spontaneous Combustion Kinetics Mechanism And Thermal Harzad Assessment Of FeS₂

The spontaneous combustion of Fe S2 is the essential reason of sulfide ores’ thermal disaster, and is also one of the severe disasters happening when metal mines are mined in self-support mining method. The sulfide ores’ thermal disaster not only wastes ore, damages equipment and causes economic loss, but also leads to environment pollution, deterioration of operating conditions, and even seriously affects worker’s health and life due to the poisonous and harmful gas producing during the sulfide ores’ spontaneous combustion. Therefore, the spontaneous combustion kinetics mechanism and thermal hazard assessment of Fe S2 must be deeply and essentially researched, which can fundamentally prevent and curb the sulfide mine disasters.On the base of the previous achievements, this paper makes a lot of work about the spontaneous combustion kinetics mechanism of Fe S2, thermal analysis kinetics, thermal kinetics parameters, the influencing factors of thermal analysis and thermal hazard assessment by theory analysis and experiments test. The main research contents and conclusions are as follows:(1)The spontaneous combustion process of Fe S2 were divided into three stages and the reaction mechanism of different stages was analyzed by thermal analysis technology. The component and content of Fe S2 sample were detected by XRD and XRF, the process of Fe S2 spontaneous combustion were divided into three stages: heating at low temperature, oxidation and self-ignition, extinguish stage on DSC and TG curve. It concluded that: Fe3 Fe Si O4(OH)5 decomposition reaction occurred in the heating stage at low temperature, and the oxidation reaction of Fe S2 happened in the stage of oxidation spontaneous combustion and its generate contains Fe2O3 and Fe O; FeS2 decomposition appeared in nitrogen atmosphere.(2)The thermal analysis Kinetics and thermal Kinetics parameters of Fe S2 spontaneous combustion were obtained. It confirms mode function of Fe S2’s oxidation mechanism by Popescu and Coats-Redfem methods, and the average activation energy values of Fe S2 sample was calculated by FWO method. Based on the transition state theory, it explains the kinetic compensation effect of Fe S2 sample’sheating and oxidation process, and calculated Fe S2 sample’s self-accelerating decomposition temperature. by the chemical reaction kinetics method, it gained the enthalpy change(△S≠), the entropy change(△H≠)and the Gibbs free energy(△G≠)at peak temperature.(3)The change law of Fe S2 spontaneous combustion were studied by the way of multi-index and multi-factor. It discussed heating rates, sample quality, particle sizes and air flow’s effects on Fe S2 sample’s thermal analysis curves, characterization parameters and reaction generates by changing single factor.(4)Thermal hazard assessment model of Fe S2 was established. Based on the reaction heat and combustion heat, chemical safety coefficient and the activation energy, the risk of Fe S2 sample were predicted and Fe S2 sample’s heat hazard was assessed. The activation energy index was used to discuss the heating rates, sample quality, particle sizes and air flow’s effects on Fe S2’s thermal hazard.