Sintered particles and methods for producing sintered particles from a slurry of an alumina-containing raw material

1. A sintered, substantially round and spherical particle, comprising:

an alumina content of from about 41.5% to 49% by weight;

a metal oxide sintering aid content of from about 1% to about 6% by weight;

an apparent specific gravity of from about 2.50 to about 3.00; and

a bulk density of from about 1.35 g/cm 3 to about 1.55 g/cm 3 .

2. The sintered, substantially round and spherical particle of claim 1 wherein the sintered particle further comprises:

a seed comprising alumina;

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

3. The sintered, substantially round and spherical particle of claim 1 , wherein the particle comprises a metal oxide sintering aid content of from about 2% to about 6% by weight.

4. The sintered, substantially round and spherical particle of claim 1 , wherein the particle further comprises silica and the ratio of alumina to silica is less than 1:1.

5. The sintered, substantially round and spherical particle of claim 4 , wherein the ratio of alumina to silica is from about 0.8:1 to about 0.9:1.

6. The sintered, substantially round and spherical particle of claim 1 , wherein the particle comprises a bulk density of from about 1.40 g/cm 3 to about 1.50 g/cm 3 .

7. The sintered, substantially round and spherical particle of claim 1 , wherein the raw material comprises at least one of kaolin clay, china clay, diaspore clay, ball clay and flint clay.

8. The sintered, substantially round and spherical particle of claim 1 , wherein the raw material comprises kaolin clay.

9. The sintered, substantially round and spherical particle of claim 1 , wherein the metal oxide sintering aid is selected from the group consisting of iron oxides, magnesium oxide, manganese oxides, titanium oxides, and oxides of the Lanthanide Series of rare earth metals.

10. The sintered, substantially round and spherical particle of claim 9 , wherein the metal oxide sintering aid comprises iron oxide.

11. A gas and oil well proppant comprising a plurality of sintered, substantially round and spherical particles, comprising:

a crush strength at 10,000 psi of from about 5 percent to about 8.5 percent;

a long term conductivity at 10,000 psi of from about 2500 mD-ft to about 3000 mD-ft;

a long term permeability at 10,000 psi of more than 140D; and

a Darcy volume factor at 10,000 psi of more than 110 Darcy-cm 3 /g;

wherein said particles comprise:

an alumina content of from about 41.5% to 49% by weight;

a metal oxide sintering aid content of from about 1% to about 6% by weight;

an apparent specific gravity of from about 2.50 to about 3.00; and

a bulk density of from about 1.35 g/cm 3 to about 1.55 g/cm 3 .

12. The gas and oil well proppant of claim 11 , wherein the proppant comprises a crush strength at 10,000 psi of from about 5 percent to about 7.5 percent.

13. The gas and oil well proppant of claim 11 , wherein the particles comprise a metal oxide sintering aid content of from about 2% to about 6% by weight.

14. The gas and oil well proppant of claim 11 , wherein the particles comprise a bulk density of from about 1.40 g/cm 3 to about 1.50 g/cm 3 .

15. The gas and oil well proppant of claim 11 , wherein the proppant has a long term permeability at 10,000 psi of from about 150 to about 175 Darcies.

16. The gas and oil well proppant of claim 11 , wherein the proppant has a Darcy volume factor at 10,000 psi of from about 115 to about 125 Darcy-cm 3 /g.

17. The gas and oil well proppant of claim 11 , wherein the metal oxide sintering aid is selected from the group consisting of iron oxides, magnesium oxide, manganese oxides, titanium oxides, and oxides of the Lanthanide Series of rare earth metals.

18. The gas and oil well proppant of claim 17 , wherein the metal oxide sintering aid comprises iron oxide.

19. A sintered, substantially round and spherical particle, comprising:

an alumina content of from about 40% to about 55% by weight;

a silica content, wherein the ratio of alumina to silica is from about 0.8:1 to 0.9:1;

a metal oxide sintering aid content of from about 1% to about 6% by weight;

an apparent specific gravity of from about 2.50 to about 3.00; and

a bulk density of from about 1.35 g/cm 3 to about 1.55 g/cm 3 .

20. The sintered, substantially round and spherical particle of claim 19 wherein the sintered particle further comprises:

a seed comprising alumina;

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

21. The sintered, substantially round and spherical particle of claim 19 , wherein the particle comprises an alumina content of from about 41.5% to about 49%.

22. The sintered, substantially round and spherical particle of claim 19 , wherein the particle comprises a metal oxide sintering aid content of from about 2% to about 6% by weight.

23. The sintered, substantially round and spherical particle of claim 19 , wherein the particle comprises a bulk density of from about 1.40 g/cm 3 to about 1.50 g/cm 3 .

24. The sintered, substantially round and spherical particle of claim 19 , wherein the raw material comprises at least one of kaolin clay, china clay, diaspore clay, ball clay and flint clay.

25. The sintered, substantially round and spherical particle of claim 19 , wherein the raw material comprises kaolin clay.

26. The sintered, substantially round and spherical particle of claim 19 , wherein the metal oxide sintering aid is selected from the group consisting of iron oxides, magnesium oxide, manganese oxides, titanium oxides, and oxides of the Lanthanide Series of rare earth metals.

27. The sintered, substantially round and spherical particle of claim 26 , wherein the metal oxide sintering aid comprises iron oxide.