Experimental Study on Crushing Characteristic of Coal and Gangue under Impact Load

Abstract

In order to analyze crushing characteristics of coal and gangue and its influence on separation effect, impact crushing experiments for coal and gangue were conducted. Crushing characteristics of coal and gangue under impact load were expressed by crushing ratio and crushing probability. Experimental results showed that crushing ratios of coal and gangue decreased with an increase of particle size and impact velocity. As the impact velocity was between 5–8 m/s and the initial particle size was between 50–100 mm, the particle size of coal obtained after crushing was between 35 mm and 45 mm. Crushing probabilities of coal and gangue increased with the impact velocity, but it was far less than that of coal under the same conditions. The lost coal rate and the mixed gangue rate were used to represent the separation effect. When the impact velocity was 7.5 m/s, the lost coal rate and the mixed gangue rate for the Xiezhuang mine coal sample were 18.285% and 25.723%, respectively. The separation effect predicted by Back Propagation Artificial Neural Network (BP-ANN) showed that the lost coal rate and the mixed gangue rate for the Xiezhuang mine coal at an impact velocity of 8.5 m/s were 3.68% and 33.35%, respectively.