Thermodynamics of Imidazolium-Based Ionic Liquids for Inhibiting the Spontaneous Combustion of Sulfide Ore

Abstract

Spontaneous combustion of sulfide ore is one of the most common disasters in the process of ore mining, storage, and transportation, which can lead to a series of safety and environmental problems, thus affecting sustainable development in society. In this paper, four imidazolium-based ionic liquids: [BMIM][I], [BMIM][BF4], [EMIM][BF4], and [BMIM][NO3], were selected for inhibition experiments with sulfide ores to reveal the inhibition performance of ionic liquids against spontaneous combustion. The results show that the main products from the reaction were Fe2O3 and SO2, produced during the process of oxidation and spontaneous combustion and that the reaction moves towards a higher temperature under the action of ionic liquid, indicating that ionic liquids have a significant inhibition effect on the spontaneous combustion of sulfide ore. At the same temperature, the apparent activation energies of the samples treated with ionic liquids were all greater than those of the control samples, indicating that imidazolium-based ionic liquids can effectively reduce the spontaneous combustion tendency of sulfide ores. In addition, compared with other ionic liquids, [BMIM][NO3] had a more pronounced inhibition effect, with the activation energies of both ore samples maximally increased by 8.4% and 10.2% after [BMIM][NO3] treatment. This is due to the ability of [BMIM][NO3] to better isolate the samples from oxygen in the air and reduce the effective collisions between active molecules, thus inhibiting and retarding the spontaneous combustion of sulfide ores.