Study On Weathering Characteristics Of Coal Gangue In Hypergenesis

Via stratified sampling,135samples were taken from the coal gangue which were selected by different weathering ages. Based on the particle group divisions and physicochemical properties tests of coal gangue samples, the characteristics of particle size distribution and other physicochemical properties of coal gangue were studied, which could provide theoretical basis for filling reclamation and others engineering applications with coal gangue. The results showed that:(1) The particle size distribution of the coal gangue is nonuniform. In upper layer, the mass percent of the coal gangue whose particle size is less than2mm or between10and20mm is higher than that of lower layer. With the increase of weathering age, the mass percent of coal gangue whose particle size is less than2mm is on the rise among sampling areas.(2) With the increase of weathering age, the Electrical Conductivity (EC) of coal gangue whose particle is less than2mm has the trend of reducing in two layers among sampling areas. The EC of the upper layer coal gangue is less than that of lower layer.(3) The pH value of coal gangue whose particle is less than2mm in each sampling area is alkaline. With the increase of weathering age, the pH value decreases in two layers among sampling areas. In the same sampling area, the pH value of the upper layer coal gangue is less than that of lower layer.(4) With the increase of weathering age, the Total Organic Carbon (TOC) content of coal gangue whose particle is less than2mm in the upper or lower layer significantly decreases among sampling areas, and the TOC content of the upper layer coal gangue is significantly less than that of lower layer in the same sampling area; also the Cation Exchange Capacity (CEC) of coal gangue whose particle is less than2mm in two layers among sampling areas increases gradually, and in the same sampling area, the CEC of the upper layer coal gangue is higher than that of lower layer in the same sampling area.(5) With the enhancement of weathering intensity, the water retention capacity of natural graded coal gangue is raised, as well as the coal gangue taken from10-20mm and2-10mm groups, and the water retention capacity of coal gangue in upper layer is higher. In the same sampling area, water retention capacity of coal gangue taken from 10-20mm,2-10mm and natural graded groups increased in turn. Characteristics of gangue particle size distribution has a significant influence on its water retention capacity, especially the coal gangue whose size is less than2mm is crucial to improve its water retention.(6) With the increasing weathering age, the point load strength of sand or clay coal gangue has a downward trend in two layers among sampling areas. In the same sampling area, the point load strength of the upper layer coal gangue (no matter sand or clay coal gangue) is a little better than that of lower layer, and the point load strength of sand coal gangue is better than that of clay coal gangue.(7) In the hypergenesis, there is a certain correlation between the particle size distribution and physicochemical properties of coal gangue, especially a good correlation between the particle size distribution and water retention capacity of coal gangue, as well as EC, TOC content, CEC of the coal gangue whose size is less than2mm.