Modification of Dumping Method by Reducing Dumping Height and Increasing Material Compaction to Increase Waste Dump Capacity in Coal Mining

Abstract

Effective waste dump management in coal mining industry is essential for reducing operational costs and optimizing waste dump capacity. One major issue faced by coal mining companies is the limited waste dump capacity due to weak strength material of sedimentary rock. This research explores the effect of modifying the dumping method by reducing the dumping height and increasing compaction by mining heavy equipment to enhance the stability and capacity of the waste dump. The existing waste dump laboratory testing data is statistically processed to determine the relationship between compaction rate (represent as material density) and strength of the waste dump material. A field experiment was conducted using a Design of Experiment (DOE) approach to analyze the impact of different compaction techniques. The study tested three factors: compaction equipment, the number of passes, and the depth of density sampling. Laboratory tests were performed on waste dump materials to evaluate changes in material compaction. A geotechnical simulation was carried out to assess the stability of the waste dump before and after compaction improvements. Regression analysis of existing waste dump data indicated a strong correlation between higher density values and improved UCS, cohesion, and internal friction angle. Field trials demonstrated that reducing the dumping layer height from 5 meters to 2 meters, combined with 20 to 30 passes of a 20-ton compactor or heavy dump truck, effectively increased the density and strength of the waste dump material from sedimentary rock. Geotechnical simulations confirmed that these improvements allowed for a steeper waste dump slope, increasing the overall slope angle from 6° to 7.5° while maintaining a Factor of Safety (FoS) of 1.32. As a result, the waste dump capacity increased from 5,444,097 BCM to 7,249,037 BCM.