Spontaneous combustion of coal seams can produce very high temperature (generally between 600 and 850 °C, even reach to 1000 °C), which greatly changes the properties of the surface loess layer, such as its magnetic susceptibility and chromaticity. In order to study a fast, effective and nondestructive method to determine the influence range of coal seam spontaneous combustion zone, and to provide important clues for the development and utilization of coal seam and burnt rock, the mass-specific magnetic susceptibility (χ) and redness chromaticity (Δa) of loess samples were measured after heating to 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C or 900 °C in a furnace. The results show that the redness chromaticity of loess increases linearly with temperature in the range of 300–900 °C, and the mass-specific magnetic susceptibility decreases suddenly above 700 °C. These changes in mass-specific susceptibility and redness chromaticity with temperature are related to the degree of iron compounds conversion.
"Acta Geodaetica et Geophysica" – Springer Journals
Published: Jun 15, 2021
Keywords: Coal spontaneous combustion; High temperature; Loess; Magnetic susceptibility; Chromaticity