Rational design of perlite-bauxite-based low-density ceramic proppants for hydraulic fracturing

To develop lightweight ceramic proppants and to promote the high-value utilization of two different forms of perlite, this study employed raw perlite and expanded perlite as partial substitutes for bauxite and fabricated low-density proppants via disk granulation followed by high-temperature sintering. The effects of perlite type, dosage (5–20 wt%), and sintering temperature (1400–1500 °C) on the microstructure and properties were systematically investigated. The results reveal that a moderate addition of raw perlite and expanded perlite significantly promotes mullite formation and reduces proppant density. However, excessive addition increases porosity, decreases the aspect ratio of rod-like mullite crystals, and induces the formation of ellipsoidal mullite, thereby elevating the breakage ratio. The optimized expanded perlite proppants sintered at 1450 °C exhibited the optimal overall performance, with a bulk density of 1.46 ± 0.01 g/cm 3 and an acid solubility of 5.98 ± 0.09 %. The breakage ratio of 8.21 ± 0.56 % under the industry-standard closure stress of 35 MPa, meeting the requirement of SY/T 51088–2014 (breakage ratio < 9 %). At a higher closure stress of 41.4 MPa, the proppants achieve a conductivity of 29.435 µm 2 ·cm. Notably, Fe 3+ incorporation into the mullite structure enhanced structural stability, thereby improving mechanical performance. This work demonstrates a sustainable strategy for fabricating low-density ceramic proppants and highlights the potential of perlite-based materials as an environmentally friendly substitute for bauxite in hydraulic fracturing applications.