Sintering mechanism of high-intensity and low-density ceramic proppants prepared by recycling of waste ceramic sands

Waste ceramic sands were effectively used to prepare the high-intensity and low-density ceramic proppants, realising the recycling of the waste ceramic sands. The technology involved the pelletising in an intensive mixer, in which the waste ceramic sands and other starting materials were added, and followed by heat-treatment under different sintering conditions. The sintering temperature, holding time and heating rate were optimised by investigating the crystalline phase, microstructure, density and breakage ratio of the obtained proppants. The results showed that the proppants sintered at 1260°C for 2?h with a heating rate of 5°C?min^–1 under air atmosphere exhibited high crush resistance and low density, with the breakage ratio of 8.5% under 52?MPa closure pressure and bulk density of 1.65?g?cm^–3. The proppants prepared by bauxite, waste ceramic sands and sintering aids are promising candidates as high-intensity and low-density fracturing proppants in future applications.