The use of Protodiakonov and Hardgrove methods to determine the effect of coal quality on its grinding ability

The factors affecting the mechanical strength of coal and coal charges, deviations of the crushing capacity coefficients' actual values of coal charges from their calculated values, and the possibility of categorizing coal in relation to the degree of its resistance to crushing have been explored. The dependence permitting satisfactory precognition of the HGI value of the coal charge placed on the data of the crushing capacity coefficients of its ingredients was settled. The effect of the grinding ability of coal on its quality indicators, namely the degree of metamorphism, petrographic and elemental composition has been examined in this article. Determination of the coal grind ability was made by means of widely known Protodyakonov and Hardgrove methods, which allow estimating the resistibility of the material to the grind forces. For research 14 samples of coals (Ukraine, USA, and Kazakhstan), and 7 testers of coal charges at the basic coke chemical companies of Ukraine, were applied. The graphical and mathematical dependences are stated to have been developed to enable the predicting of the grinding ability of coals using the Hardgrove (HGI) and Protodyakonov (f) methods, based on determining the indicators of their quality (C(daf), R(0), O(d)(daf), V(daf)). It is shown that the graphical and mathematical dependencies are polynomials of the second degree, and the values of the coefficients of determination (R(2)) exceed 0.550–0.930. For the initial time, the coherency between the strength coefficient according to the Protoyakonov method and coal pulverization to the Hardgrove method was established. It was found the f and HGI values of measure are inversely in proportion, and a mathematical and diagram dependence based on one of them for its prognosticate has been established.