Selective spherical agglomeration of coal: An amended mechanism of agglomerate formation and growth and its effect on product quality

Abstract

The mechanism of agglomerate formation during the selective spherical agglomeration of fine coal with oil was investigated. The effect of agglomerate size on the amount of mineral matter and water entrapped within the agglomerates, i.e. the quality of the final beneficiated product, was also investigated. Scanning electron microscopy (SEM) revealed that during the initial stages small, closely packed agglomerates of coal fragments are formed. Upon further agitation, these primary agglomerates combine into secondary and even tertiary agglomerates. Process water containing liberated mineral matter is trapped between the primary agglomerates which make up the secondary agglomerates. This increases the internal water content and the ash content of the product. It was found that the mineral matter and water content increased with an increase in agglomerate size. The SEM observations were in good agreement with the analytical results.