RECYCLING OF COAL GANGUE TO PREPARE LOW DENSITY CERAMIC PROPPANTS FOR COAL BED METHANE WELLS

Low density ceramic proppants for coal bed methane wells were successfully prepared using flint clay and solid waste coal gangue as raw materials.The addition of coal gangue greatly reduced the preparation cost.The phase composition and morphology of the proppants were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The results showed that the main crystal phases were rod-shaped mullite and granular cristobalite.Furthermore, the suitable amount of coal gangue added was 30 -40 wt.%.Proppants prepared with 30 wt. % and 40 wt.% coal gangue and sintered at 1300 °C and 1350 °C had bulk densities of 1.252 g•cm -3 and 1.291 g•cm -3 and breakage ratios of 8.7 % and 6.4 % under 35 MPa closed pressure, respectively, while for those sintered at 1400 °C, the breakage ratio was 8.9 % under 52 MPa closed pressure.