Fast and selective fine coal agglomeration using an economic binder

Selective agglomeration using an oil binder has been considered for the processing of fine coal many times in the past. However, the cost of the oil binder has always proven to be too high for commercial applications. This work revisited the technique of fine coal agglomeration in an effort to create an economically viable process and, thus, increase the overall utilisation of the coal resource. A novel and economic binder which consisted of a water-in-oil emulsion (95 vol% water and 5 vol% oil) was introduced. This emulsion was considered to be an economic alternative to pure oil as it had the potential to drastically reduce the amount of oil required in the process. A reduction was possible as the dispersed water droplets within the emulsion occupied the majority of the void space within the agglomerate; a space which would otherwise have to be filled with oil. In other words, the emulsion possessed an enhanced space-filling functionality. The use of oil as the continuous phase also meant that the necessary hydrophobic surface functionality of the binder was maintained. In this study the selectivity of the new emulsion binder was investigated and compared to the selectivity of a pure kerosene binder. The coal feed used in the study contained particles in the size range of 0 – 2 mm which also afforded the opportunity to study the ability of the emulsion to agglomerate and recover coal over a broad size range. It was found that the selectivity of the emulsion matched that of pure kerosene and consistently resulted in a low, <15 (% ad), ash product. An analysis of the product agglomerates indicated that the emulsion could agglomerate particles up to 1 mm.