Patent pending announcement., page-6

LWP Patent
http://www.google.com/patents/WO2015026585A1?cl=en

Proppant material incorporating fly ash and method of manufacture
WO 2015026585 A1
Abstract
A relatively low density, high strength round proppant material having (i) a round core made of a sintered mixture of fly ash and clay or, in some instances, fly ash, clay, and bauxite; and (ii) an outer shell made of sintered bauxite, and a method of making the same. The proppant materials which may be used in hydraulic fracturing operations in oil and gas wells.

Claims  (OCR text may contain errors)
CLAIMS What is claimed is:
1. A round proppant material comprising: a core comprising lignite fly ash and clay; and a coating comprising bauxite surrounding said core.
2. A round proppant material comprising: a core comprising fly ash, bauxite, and clay; and a coating comprising bauxite surrounding said core.
3. The proppant of claim 2, said core comprising about 70% fly ash, about 15% bauxite, and about 15% clay.
4. The proppant of claim 2 said clay comprising kaolin clay.
5. The proppant of claim 2 in which the iron oxide content of the fly ash is 12% or less.
6. The proppant of claim 2 in which the iron oxide content of the fly ash is about 7% or less.
7. The proppant of claim 2 in which the iron oxide content of the fly ash is about 4% or less.
8. The proppant of claim 2 in which said coating has more than one layer.
9. A method for manufacturing a round proppant material comprising the steps of: forming round granules comprising lignite fly ash and clay; coating said round granules with a coating comprising bauxite to form coated round
granules; heating said coated round granules to a temperature of at least 1080° C.
10. A method for manufacturing a round proppant material comprising the steps of: forming round granules comprising fly ash, bauxite, and clay; coating said round granules with a coating comprising bauxite to form coated round
granules; calcining said coated round granules; and sintering said coated round granules at a temperature of at least about 1200° C.
1 1. The method of claim 10 in which said coating comprising bauxite is applied in more than one layer.
12. The method of claim 10 in which said coating is applied in powder form.
13. The method of claim 10 in which said coating is applied in the form of a slurry containing powdered bauxite.
14. The method of claim 10 in which said coating is applied in the form of a slurry comprising powdered bauxite and a binder.
15. The method of claim 14 in which said binder comprises polyvinyl alcohol.
16. The method of claim 11 in which at least one of the layers of said coating contains a larger total amount of bauxite than a previously applied layer.
17. The method of claim 10 in which said coated round granules are sintered at a temperature of about 1240° C - 1280° C.
18. The method of claim 10 in which said round proppant material has a compressive strength of at least 10,000 psi.