Weathering characteristics of coal gangue in hypergenesis: a case study on Huainan coal mining area

Via stratified sampling, 135 samples were taken from the coal gangue which were selected by different weathering ages. Based on the particle group division and quantitative tests of water retention capacity of these coal gangue samples, the size distribution characteristics and water retaining capacity variation of coal gangue were studied, which could provide theoretical basis for engineering application and filling reclamation with coal gangue. The results show that the particle size distributions of the coal gangue from different sample areas or with different degrees of exposure are nonuniform. In upper layer, the mass percent of the coal gangue whose particle size is less than 2 mm or between 2 and 10 mm is higher than that in lower layer. With the increasing weathering age, the mass percent of coal gangue less than 2 mm is on the rise among sampling areas. With the enhancement of weathering intensity, the water retention capacity of natural graded coal gangue goes up, as well as the coal gangue taken from 10-20 mm and 2-10 mm groups; the water retention capacities of coal gangue in upper layer is higher indicating that in hypergenesis, the water retention capacity of coal gangue of same size is affected by weathering degree. In the same sampling area, water retention capacities of coal gangue taken from 10-20 mm, 2-10 mm and natural graded groups increase in turn namely characteristics of coal gangue particle size distribution have significant influence on its water retention capacity, and the coal gangue whose size is less than 2 mm is especially crucial to improve its water retention ability. There is a good correlation between the characteristics of particle size distribution and water retention capacity of coal gangue. ©, 2015, China University of Mining and Technology. All right reserved.