METHODS FOR PRODUCING SINTERED PARTICLES FROM A SLURRY OF AN ALUMINA-CONTAINING RAW MATERIAL

• US 20100059224A1
• Filed: 09/21/2009
• Published: 03/11/2010
• Est. Priority Date: 03/01/2005
• Status: Active Grant

• Current Assignee: Carbo Ceramics Incorporated
• Original Assignee: Carbo Ceramics Incorporated
• Inventors: Palamara, Thomas C., Wilson, Brett Allen
• Granted Patent: US 8,216,675 B2
• Time in Patent Office: Days
• US Class Current: 166/280.200
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/528 Spheres
• CPC Class Codes: C04B 2235/5463 Particle size distributions
• CPC Class Codes: C04B 2235/656 characterised by specific heating conditions during heat treatment
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 35/185 Mullite 3Al2O3-2SiO2
• CPC Class Codes: C04B 35/6263 characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: C04B 35/62635 Mixing details
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/62813 Alumina or aluminates
• CPC Class Codes: C04B 35/63424 Polyacrylates; Polymethacrylates
• CPC Class Codes: C09K 8/80 Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open
• CPC Class Codes: Y10S 507/906 Solid inorganic additive in defined physical form
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

Methods for producing substantially round, spherical and sintered particles from a slurry of a calcined, uncalcined or partially calcined raw material having an alumina content of more than 55% by weight, and a mullite growth promoter in an amount of from about 2 to about 10% dry weight of the total solids in the slurry. Methods for using such substantially round, spherical and sintered particles in hydraulic fracturing operations.

Claims

1. 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.

2. The method of claim 1 wherein the slurry has an alumina content and the seeds have a alumina content, and wherein the slurry alumina content is 10% less than the seed alumina content.

3. The method of claim 1 wherein the slurry has an alumina content and the seeds have a alumina content, and wherein the slurry alumina content is 10% greater than the seed alumina content.

4. The method of claim 1 wherein the substantially round and spherical sintered particles have an alumina content from about 60 to about 70% by weight, and an iron oxide content from about 4 to about 10% by weight.

5. The method of claim 1 wherein the droplets form a coating on the seeds that comprises at least about 80% of the total volume of the substantially round and spherical sintered particle.

6. 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.

7. The system of claim 6 further comprising at least one of:

a tank operable to receive a feed of the slurry from the blunger, and to mix a binder with the slurry;

a grinding mill operable to grind particles in the slurry to a target size before the slurry is fed to the fluidizer;

a pump system operable to receive a feed of the slurry from the heat exchanger and to provide a pressurized feed of the slurry to the fluidizer; and

a drier operable to dry the particles before the particles are sintered.

8. The system of claim 6 further comprising at least one of:

a first screening unit operable to screen the slurry to a target size before the slurry is fed to the fluidizer;

a second screening unit operable to receive the particles from the fluidizer and screen the particles for size prior to sintering; and

a third screening unit operable to receive the sintered particles from the sintering device and screen the sintered particles for size.

9. A substantially round and spherical sintered particle comprising:

a seed comprising alumina; and

a coating comprising alumina, wherein the coating comprises at least about 80% of the total volume of the substantially round and spherical sintered particle.

10. The substantially round and spherical sintered particle of claim 9 wherein:

the coating is formed from a slurry that is sprayed onto the seed, wherein the slurry is prepared from a raw material having an iron oxide content in a range of from about 2 to about 10% by weight of total solids in the slurry, and having a first alumina content;

the seed has a second alumina content; and

the first alumina content is at least 10% less than the second alumina content.

11. The substantially round and spherical sintered particle of claim 9 wherein:

the coating is formed from a slurry that is sprayed onto the seed, wherein the slurry is prepared from a raw material having an iron oxide content in a range of from about 2 to about 10% by weight of the total solids in the slurry, and having a first alumina content;

the seed has a second alumina content; and

the first alumina content is at least 10% greater than the second alumina content.

12. The substantially round and spherical sintered particle of claim 9 wherein the sintered particle has:

an alumina content of greater than about 55% by weight; and

an iron oxide content in a range of from about 2 to about 10% by weight.

13. The substantially round and spherical sintered particle of claim 9 wherein the sintered particle has:

a specific gravity in a range of from about 2.70 g/cm³ to about 3.50 g/cm³;

a bulk density in a range of from about 1.55 g/cm³ to about 1.95 g/cm³;

a crush strength at 10,000 psi of from about 4 percent to about 7 percent; and

a short term conductivity at 10,000 psi of from about 3000 mD-ft to about 3800 mD-ft.