Preparation of drilling cuttings-coal fly ash based ceramic proppants: The roles of barite

This study presents the feasibility of preparing ceramic proppants (CPs) using drilling cuttings (DCs) and coal fly ash (CFA) via high-temperature sintering. The reaction behavior of barite in ceramic proppant precursors originating from DCs during the sintering process was investigated. The breakage ratio of the CPs (optimal group S3) met the requirements of Chinese standard SY/T 5108-2014 (2 K grade). The primary chemical reactions (7–8 in Table 4) between the barite and silica/alumina components resulted in a reduction of the eutectic point of the mixtures and the formation of aluminosilicates containing barium. However, these interactions also released gases (SO2 and O2), which created pores and weakened the CPs strength. The ideal temperature range for sintering is between 1170 and 1200 °C, during which there should be a gradual weight loss and minimal gas generation. This range will also ensure that the appropriate amount of liquid phase is present, which will have a moderate viscosity and aid in the densification of the ceramic proppants, as well as the formation of a dense enamel layer. The composite reactions of barite in the S3 sample follow a one-and-a-half-order chemical reaction mechanism within the temperature range of 950–1200 °C. The average activation energy and pre-exponential factor were 583.304 kJ mol−1 and 5.81 × 1020 min−1, respectively. The kinetic and reaction rate equations for the composite reactions were (1 − α)−1/2–1 = (5.81 × 1020 × e−5.83 × 10^5/RT) × t and dα/dt = (2(1 − α)3/2) × (5.81 × 1020 × e−(5.83 × 10^5)/RT)), respectively. This study provides a theoretical basis and guidelines for large-scale production of CPs using DCs and CFA.