Theoretical and experimental investigation into the moisture migration characteristics of coal during oscillatory motion

It is a common occurrence that the moisture migrates during coal handling, such as storage, conveying and shipping. This results in a non-uniform moisture distribution giving rise to problems in handling. Current theories and mathematical models are mainly focused on static moisture migration, which is not suitable for dynamic moisture migration scenarios. To find out how moisture migrates in coal during oscillatory like motion, a theoretical model is established based on the Green-Ampt equation. The theoretical model assumes that hydraulic conductivity is an average value and water can be drained from the bottom. An oscillation factor is introduced to the hydraulic conductivity to suit the oscillation condition and a water-voids ratio is added to suit the model in an unsaturated drainage. These factors, including water based particle density, free drained saturation (FDS) moisture content, particle size distribution, are obtained through experiments. The predicted value of drained water from the theoretical model is validated by shipping log data of drained water from coal, which proves the model is practicable for calculating the mass of drained water of coal during oscillatory like motion.