Influence of Refuse Content on Economic Benefits for Fully Mechanized Top Coal Caving

Abstract

In order to study the influence of refuse content on economic benefits and realize ending drawing top-coal reasonably for fully mechanized top coal caving, relationship between refuse content and drawing interval has been analyzed, and drawing law of loose top-coal with different drawing interval has been simulated by PFC2D software. When refuse content properly increases, drawing ratio will be improved largely if the caved ellipsoid is tangent with one coal-gangue boundary and intersectant with another. Drawing ratio of different drawing interval is obviously different when refuse content increases. Besides, with refuse content increasing, the profit increasing rate rises rapidly and then slowly decreases. It also concludes that economic refuse content is 6%-10%. Meanwhile, gangue ratio among coal-gangue flowing slowly increases with refuse content rising and then fluctuates. Finally, gangue ratio tends to periodic changes and also shows signs of increasing. From technological and economic perspective, drawing top-coal should be ended when gangue ratio among coal-gangue flowing is 15%-25% and drawing ratio is about 98%. Then the refuse content will be controlled at 8% and the maximum economic benefits of the mine will be achieved.