Impact of coal mass structure on fragmentation during mining and processing

Coal fragmentation is a function of the material strength, lithotype bedding and banding, and fracture of a given seam and is induced through the application of energy during the mining and handling process. A large field and laboratory based project was designed to measure, model and understand this process so that tools can be developed to optimise fragmentation in the mining process. Field audits were conducted during which coal seams were characterised in situ and discrete parcels were mined blasted and free dug and then tracked through the handling and crushing stations. Samples of ROM, crusher product and breaker product and reject were sized and analysed for washability. The results show that the results of fragmentation can be linked to the inherent band size distribution of the coal. Band thickness distributions can also be used as an input to blast fragmentation models. The results also show that mining method does not significantly impact on the final size distribution of the ROM. However, it does impact significantly on downstream processing behaviour. Although size distributions of breaker product were similar for the blasted and free dug coals from the same block, the washability of the coarse and fine coal from each trial were significantly different