Preparation of Low Ash COM (Coal Oil Mixture)

Abstract

Taiheiyo coal (32-60 mesh) containing 7.2 wt % (dry basis) of ash and 4.61 wt % of water, was wet ball-milled with aqueous solution of HC1 or NaOH. The precursor of COM was prepared in the flushing method or the oil agglomeration method, by which the coal particles were transferred directly from each aqueous slurry to petroleum. In these processes, most part of the mineral matter was removed from the coal particles and remained in the aqueous phase.In the flushing method, ash content of the coal was decreased to 4.1 wt %. It was found that the flushing of the coal particles to oil phase depended on pH of aqueous phase, that is, the coal particles were transferred completely from the aqueous slurry to the petroleum in the range below pH 7, however the coal particles were not flushed at all in the range above pH 9.In the oil agglomeration method, furthermore, ash content of the coal was decreased to 2.2wt%, and water content in the coal oil agglomerates (Coal: Oil=5: 3) became about 2.0wt%.