Physicochemical Characteristics and Their Variation of Coal Dust Originating from Underground Mining Sites

The physicochemical properties of coal dust significantly affect its toxicity and dust suppression efficiency. Currently, lab-crushed coal dust is commonly used for characterization instead of the original coal dust (OCD) sampled from underground mining sites. This practice leads to an inaccurate understanding of the underground coal dust properties. To address this issue, the study directly collected 18 OCD samples from various underground mining sites and characterized their physicochemical properties, and the variation of these physicochemical parameters of OCD with various coal rank were analyzed. The results show: OCD has a small particle size (average 26.49 μm), and around 21% of particles are under 10 μm. OCD has a well-developed pore structure, with an average total pore volume of 8.24 × 10^-3 cm³/g and an average specific surface area of 8.24 m²/g. OCD samples have a high oxidation degree, and the average relative content of total oxygen-containing functional groups is 45.71%. Between the 32 measured physicochemical parameters of OCD, 10 moderately correlates with R ₀ and 6 highly correlates with R ₀. These parameters mainly involve wettability, pore structure, moisture content, and elemental composition. The findings present valuable insights into accurately assessing the toxicology and health risks of coal dust in underground mining sites and for selecting efficient dust control technologies in different coal mines.