St. Petersburg Mining University (St. Petersburg, Russia):
Pashkevich M. A., Head of Chair, Professor, Doctor of Engineering Sciences, mpash@spmi.ru
Sverchkov I. P., Postgraduate Student, sverchkov@spmi.ru
Chukaeva M. A., Postgraduate Student, shellx@bk.ru

Coal-preparation waste utilization as raw material for coal-water fuel slurry production has been studied. The laboratory testing was performed on the Kuzbass coal-preparation plant waste coal samples. It was established that sufficient stability of slurried coal is achieved at solid phase size over 92 microns, therefore, specimen of this size was used for subsequent experiments. In order to determine burning parameters of the chosen coal-preparation waste specimen and coal-water fuel, prepared from it, thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were carried out. In the course of the experiment, the specimens were placed into platinum crucibles and heated in them from 40 to 1200 °С at the rate of 30 °С/min. Upon reaching the temperature over 970 °С, mass of both specimens stops changing and DSC-curve stabilizes, which is evidence that physico-chemical processes have ceased. The initial coal released energy of burning was 18.3 KJ/g, and that of produced fuel slurry — 16.4 KJ/g, without considering moisture. Energy losses in burning are caused by endothermic reactions that take place with water evaporation at the starting stage. A conclusion is made that the studied coal-preparation wastes may be utilized as raw material for coal-water fuel slurry production in the coal mining area. A certain decrease of coal-water fuel slurry calorific efficiency in comparison with dry coal slime is compensated by a significantly lower level of incomplete burning of carbon. Coal-preparation waste utilization will permit to decrease man-caused ecological impact, as well as to decrease the land areas taken for construction of wastes storage facilities.

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