Methods for producing sintered particles from a slurry of an alumina-containing raw material

A system for producing sintered particles comprising:

• a source of raw material having an alumina content in a range of from about 55 to about 80% by weight;
• a blunger operable to receive a feed of the raw material, and to prepare a slurry from the raw material by mixing the raw material, water, and a mullite growth promoter, which mullite growth promoter is present in the slurry in an amount of from about 2 to about 10% by weight of the total solids in the slurry;
• a heat exchanger operable to heat the slurry to a temperature of from about 25° C. to about 90° C.;
• a fluidizer comprising at least one nozzle and a particle bed, wherein the fluidizer is operable to receive a pressurized feed of the slurry and pump the slurry under pressure through the at least one nozzle as a spray, and wherein the particle bed is populated with seeds, which seeds are coated with the slurry spray to form particles;
• and
• a sintering device operable to receive and sinter at least a portion of the particles formed by fluidizer, which sintering is performed at a temperature of from about 1000° C. to about 1600° C. for about 5 to about 90 minutes, to form sintered particles having an alumina content of greater than about 55% by weight, an iron oxide content in a range of from about 2 to about 10% by weight, a specific gravity in a range of from about 2.70 g/cm3 to about 3.50 g/cm3, and a bulk density in a range of from about 1.55 g/cm3 to about 1.95 g/cm3.

A method of fracturing a subterranean formation comprising:

• injecting a hydraulic fluid into the subterranean formation at a rate and pressure sufficient to open a fracture therein;
• and
• injecting a fluid containing substantially round and spherical sintered particles into the fracture, wherein the substantially round and spherical sintered particles:
• have an alumina content of greater than about 55% by weight, an iron oxide content in a range of from about 2 to about 10% by weight, a specific gravity in a range of from about 2.70 g/cm3 to about 3.50 g/cm3, and a bulk density in a range of from about 1.55 g/cm3 to about 1.95 g/cm3;
• and
• were formed by preparing a slurry having a solids content of from about 40 to about 60% by weight, and comprising water, a binder, a mullite growth promoter and a raw material having an alumina content in a range of from about 55 to about 80% by weight;
• atomizing the slurry into droplets;
• coating seeds comprising alumina with the droplets to form green particles;
• and
• sintering at least a portion of the green particles at a temperature of from about 1000° C. to about 1600° C. for about 5 to about 90 minutes.