Caving mechanisms of loose top-coal in longwall top-coal caving mining method

摘要

The top-coal caving mining method, developed steadily in the past two decades, has become the main method for thick seam coal mining in China. In recent years, the core research areas in the top-coal caving mining are the mechanisms of top-coal caving and the improvement of top-coal recovery ratio. In this paper, the mechanisms of the top-coal caving are illustrated by a large number of physical simulation experiments and numerical modelings of actual cases. The marker method, which has sufficient accuracy to calculate the top-coal recovery ratio, is also described in detail. Coal is the largest energy source in China, accounting for 70% of the primary energy production and consumption. Coal production was 3.5 billion metric tons in 2011, about 50% of the global coal production. In the next few years, production is expected to increase steadily at the rate of 200 million metric tons each year. According to the preliminary estimation, coal production will peak at 4.5 billion metric tons. In China, thick seam mining, referring to those more than 3.5 m thick, is the key to achieving high produc-ion and high efficiency coal mining. Currently, both the reserve and production of thick seam coals account for 45% of the under-ground coal resources and production in China. Therefore, thick seam coal mining plays a very significant role in the performance of Chinese coal industry [1].