Effects of water immersion on the pore structure and thermodynamic properties of sulfide ores

Spontaneous combustion of sulfide ores represents a significant challenge in metal mining operations. Mines that have experienced spontaneous combustion of sulfide ores normally possess well-developed underground water systems. Consequently, it is essential to investigate the spontaneous combustion characteristics of sulfide ores through water immersion. In this study, samples from representative high-sulfur mines were selected and ground. The study was primarily conducted through nitrogen adsorption, X-ray diffraction, and thermogravimetry on the physicochemical properties of water-immersed sulfide ores under varying immersion times (25, 50, 75 days). The sulfur content and the talc content of water-immersed sulfide ores exhibited a decline with the progression of leaching time. Additionally, the average grain size exhibited a reduction, while the average pore diameter exhibited an expansion of 0.36 nm. Furthermore, the average pore volume exhibited an enlargement of 5.71 × 10^–3 cm³ g^-1. However, the specific surface area exhibited a reduction of 0.8735 m². The activation energy of the ore samples was calculated using the Flynn–Wall–Ozawa method and the Kissinger–Akahira–Sunose method. The results demonstrated a very strong linear correlation between the activation energy of the samples and the leaching time within 50 days. It can be observed that the water-immersed sulfide ores exhibit a heightened propensity to spontaneous combustion as a result of alterations to the material components, crystal structure, and pore space.