A Kinetic Study of a Modified Fine Coal Agglomeration Process

Abstract

The process of fine coal agglomeration is a beneficiation technique that uses an organic liquid, such as, diesel, to agglomerate fine coal from an aqueous suspension of coal and mineral particles. The organic binding liquid is dispersed in the aqueous suspension through the application of agitation and selectively wets and agglomerates the hydrophobic coal particles. The hydrophilic mineral particles remain finely dispersed and, thus, the product coal agglomerates can be easily retrieved by passing the suspension over a screen. Fine coal agglomeration can achieve high quality beneficiation and allows for more effective dewatering of a fine coal feed. Regardless of these excellent capabilities, however, there are no industrial applications of this process. This is because the high cost of the oil makes the process economically unfeasible. Therefore, in this study a modified fine coal agglomeration process has been investigated in which the aim is to reduce the amount of organic liquid required in the process. The modification involves the use of a water-in-oil (W/O) emulsion as the immiscible binding liquid, replacing the conventional pure oil approach. A high internal phase (HIP) emulsion is used as it provides the interfacial functionality of the oil, while the space filling functionality is provided by the stabilised internal water droplets. In this study, an investigation into the kinetics of agglomeration of the modified process was undertaken. It was found that complete agglomeration of the carbonaceous material in the feed could be achieved by the emulsion binder in one third of the time required for a pure diesel binder. In addition, the improved kinetics were achieved by the emulsion binder at an organic liquid dosage of five-times less than required by a pure diesel binder.