Grindability of Coal Changing with Burial Depth

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ABSTRACTGrindability of a coal is generally represented in terms of the Hard Groove Grindability Index (HGI); a coal of lower HGI needs more energy to be ground. Samples of this study were taken from the Amasra coalfield of the Zonguldak Hard Coal Basin to determine if coal grindability varies with the burial depth of coals. Samples from different burial depths were analyzed and corresponding HGI values were obtained. HGI values of the original samples were found between 51.43 and 79.26. A float-and-sink analysis was performed for some of the original samples and it was found that the HGI values of floated coal samples change between 49.04 and 73.52.A new method, which employs proximate and petrographic analysis data and the burial depth, was proposed for the prediction of HGI. Correlation of HGI with burial depth or the discrimination of floated and original coal currently exists. Correlations of the proposed methods have satisfactory coefficient of determination values (R2 =.75, R2 = .86) for the original and floated coal samples studied. This new proposed method was tested on the data and the previously studied original and floated coal samples of the Zonguldak coalfield and yielded a good correlation (R2 = .87, R2 = .90). The proposed method can be considered to yield reasonable predictions for the Amasra coalfield.