THE LOW TEMPERATURE PREPARATION OF ULTRA LOW-DENSITY CERAMIC PROPPANTS BY ADDING FLY ASH

Ultra low-density mullite-corundum based ceramic proppants were prepared from fly ash, bauxite, manganese dioxide and dolomite through a low temperature sintering method.The bulk density and breakage ratio of the proppants were systematically investigated as functions of the sintering temperature and the fly ash content.The morphology structure and phase composition of the different proppants were investigated by scanning electron microscopy and X-ray diffraction.The proppants were composed of corundum, prismatic mullite and glass phases.The fly ash introduction promoted the formation of prismatic mullite crystals at a lower sintering temperature.As the fly ash content increased, the prismatic mullite phase increased, but the apparent density decreased.The proppants containing 30 wt. % of fly ash and 65 wt.% of alumina sintered at 1200 °C exhibited an apparent density of 2.47 g•cm -3 and a breakage ratio of 8.35 % under 35 MPa.Such a low density and sintering temperature, with sufficient crush resistance strength, were due to the structure of the interlocked mullite and corundum phases.