Abstract: Disclosed is a process for producing ceramic particles, such as proppants, that have at least 10 percent total porosity. The process includes forming a particle precursor that includes 5 percent to 30 percent of a first ceramic material and at least 40 percent of a second ceramic material. The sintering temperature of the first ceramic material may be lower than the sintering temperature of a second ceramic material. Heating the precursor to a maximum temperature above the sintering temperature of the first material and below the sintering temperature of the second material. Also disclosed is a ceramic article that has a particular combination of chemistry and alumina crystalline phase.

Abstract: A sintered ceramic particle made from a ceramic material having a true density greater than 3.5 g/cc and a composition having no more than 30 weight percent silicon oxide and at least 15 weight percent iron oxide, based on the combined weight of the oxides of aluminum, iron and silicon, is disclosed. A process that utilizes an externally applied compressive force to make a ceramic particle is also disclosed.

Abstract: One embodiment of the present invention relates to spherical ceramic elements, such as proppants, for maintaining permeability in subterranean formations to facilitate extraction of oil and gas therefrom. The strength of the ceramic element may be enhanced by combining materials having different coefficients of thermal expansion. Methods of making the ceramic elements are also disclosed.