Significance and application of the caking index of coal — Ten years' review

The Caking Index, G, has been widely popularized and applied in coal geological exploration, production and utilization departments in China. This index was established after improving the Roga Index, an international method used for determining the caking power of bituminous coal. It has become one of the main indices to classify bituminous coals in the new classification of Chinese coals. The value of G characterizes the content of active component of coal, and is considered as a measure of the degree of reduction of coal. The method using a plot of the volatile matter content (V, d.a.f.) vs. G can predict the coke strength and permits selection of the best economic coal blending ratios. The additive property of G values and the interchangeability of coal types in coal blending for coking are discussed.