Crushing Properties of Coal 3. Method of Determining the Protod’yakonov Strength Coefficient

Determination of the coal-strength coefficient in accordance with State Standard GOST 21153.1–75 is clear and simple. No complex equipment is required, and capital expenditures and energy costs are relatively low. This method satisfactorily reproduces the crushing conditions of coal in hammer systems, and the granulometric composition of the ground sample is close to industrial values. The relations of the composition, structure, and properties of coal from Ukraine, Russia, the United States, and Kazakhstan with the Protod’yakonov strength coefficient are investigated. It is shown that the Protod’yakonov strength coefficient decreases with increase in the vitrinite reflection coefficient, the carbon content, and the Hardgrove grindability index and also with decrease in volatile matter, the oxygen content, and the mean diameter of the coal particles. The derived mathematical formulas permit prediction of the Protod’yakonov strength coefficient with satisfactory accuracy on the basis of the carbon content, the oxygen content, volatile matter, the vitrinite reflection coefficient, the mean particle diameter, and the Hardgrove grindability of the coal.