Effective Utilization Technique for Coal Having High Maximum Fluidity and Long Maximum Permeation Distance by Weathering Processing

Abstract

In our previous study, it was revealed that high MF coal having longer "maximum permeation distance", which was developed as a unique thermoplasticity index, forms lower roundness pores and thinner porewall structures in coke and that coke strength deteriorated when the coal blend included the longer maximum permeation distance coal. Therefore, techniques for reducing the adverse effects of long maximum permeation distance coal on coke strength are essential so as to utilize the coal more efficiently. Some practical techniques of design and control regarding coal grain size were developed for ameliorating coking property of long maximum permeation distance coal in our previous paper. The techniques are based on the facts that the coke strength deterioration caused by long maximum permeation distance coal in coal blend was suppressed with decreasing the coal size. In this paper, influence of weathering, which is mild oxidation with air atmosphere, on permeation distance and coke strength were researched in order to clarify possibilities of controlling maximum permeation distance in another way of the techniques of coal size adjustment. As a result, it was found that the measured maximum permeation distance and coke strength deterioration caused by long permeation distance coal was reduced by weathering processing although the fluidity was impaired. Accordingly, some control techniques of maximum permeation distance by weathering were proposed for more effective utilization of long maximum permeation distance coal.