Dependence of coal liquefaction behaviour on coal characteristics. 4. Cluster analyses for characteristics of 104 coals

In an extension of earlier work, the conversion of 104 high volatile bituminous coals at 400 °C with tetralin has been determined in duplicate with the aid of a new reactor system. For the whole set of coals, volatile matter and vitrinite reflectance have the highest correlation coefficients with conversion (0.85 and ?0.84, respectively). However, tests showed that the sample set contained more than one population. Cluster analysis partitioned the set into three reasonably homogeneous populations. A factor representing sulphur content was the major contributor from a set of variables in separating the coals into groups, with smaller contributions from factors related to rank and petrographic composition. Each of the groups contained samples mostly from one geological province, but 11 coals of relatively high sulphur content from the Eastern province were clustered in a group that contained also 25 coals from the Interior province. The ranges of conversion are distinctly different for the three groups, and the three regression equations developed for correlating conversion each require a different set of coal properties. The possible general significance of the clustering of coals into groups as a novel basis for classification is discussed.