Law of characteristic gases production in the low-temperature oxidation stage of spontaneous combustion of sulfide ores

To explore the gas early warning index suitable for spontaneous combustion of sulfide ores, three kinds of sulfide ore concentrates (pyrite, Melnikovite, and pyrrhotite) and sulfide ores collected from Dongguashan Mine were selected for investigation. Temperature-programmed and gas-detection experiments were conducted in the low-temperature oxidation stage (0 ∼ 100 °C). In the experiment, temperature-programmed heating was carried out on sulfide ores of different types and sizes, and a gas detector analyzed the concentration of characteristic gas in the gas produced by the experiment. The experimental results show that when the temperature reaches 80 ℃, the sulfide ores produce the characteristic gases of H₂S and SO₂, and the gas concentration increases with the increase in temperature. There is a specific correlation between the concentration of H₂S and SO₂. Between 80 ℃ and 100 ℃, the concentration of SO₂ gas is about 2.8 times that of H₂S. The particle size is also an important and complex factor affecting the reaction of ore-producing gas. The smaller the particle size, the larger the specific surface area of the contact reaction between ore and oxygen, but at the same time, the more difficult it is for oxygen to penetrate the ore and fully contact with the ore. Finally, The Initial Characteristic Temperature (TICT) of the spontaneous combustion characteristic gas of sulfide ore was found and defined from the experimental results. This study can provide a reference for developing early warning indicators for the spontaneous combustion of sulfide ores. © 2024 Elsevier Ltd