Abstract: A method of hydraulic fracturing of a subterranean formation having a well bore includes steps of sequentially injecting different slurries with nano, micro and then macro sized proppants generated from coal ash into the well bore in order to enhance oil and gas production from fracking. A slurry useful in the method includes (a) water, (b) coal combustion fly ash particles that have a mean particle size (d50) of about 6 microns and (c) a surfactant.

Abstract: The invention provides a cementitious composition comprising a cement component comprising (i) an accelerant, (ii) a calcium sulphate source and (iii) an ettringite forming cement; an aggregate; and optionally water; wherein the cement has a minimum unconfined compressive strength of 1500 psi when tested in accordance with ASTM C1140 and/or C1604 at 15 minutes after placement; methods for its use and concrete formed from it.

Abstract: The invention provides a cementitious composition comprising a cement component comprising (i) an accelerant, (ii) a calcium sulphate source and (iii) an ettringite forming cement; an aggregate; and optionally water; wherein the cement has a minimum unconfined compressive strength of 1500 psi when tested in accordance with ASTM C1140 and/or C1604 at 15 minutes after placement; methods for its use and concrete formed from it.

Abstract: A method for selective separation of particles from a particle-containing material includes preparing a slurry of the particle-containing material and a dispersant, passing the slurry through a hydraulic classifier in a first direction, establishing a particle flow in a direction that is different from the first direction, and recovering particles having a mean particle size of about 2-7 ?m. The flow of particles defines a cross-current flow relative to the slurry feed direction. The method further includes providing the classifier with an interior divider assembly defining at least one inclined channel. The divider assembly typically includes a plurality of substantially parallel dividers separating the classifier into multiple channels having a substantially equal internal volume. A hydraulic classifier for separating particles having a mean particle size of from about 2-7 ?m in accordance with the present method is provided also.

Abstract: A method for preparing a metal-fly ash composite material includes classifying a fly ash-containing material to provide a classified fly ash material having a mean particle size of from about 4 ?m to about 40 ?m. The classified fly ash material is blended with a metal matrix whereby the fly ash material and the metal matrix form a substantially homogenous mixture. Suitable conditions of temperature and/or pressure are applied to form a metal-fly ash composite material is formed. The metal matrix may be provided as a liquid or as a powder.

Abstract: A method for selective separation of particles from a particle-containing material includes preparing a slurry of the particle-containing material and a dispersant, passing the slurry through a hydraulic classifier in a first direction, establishing a particle flow in a direction that is different from the first direction, and recovering particles having a mean particle size of about 2-7 ?m. The flow of particles defines a cross-current flow relative to the slurry feed direction. The method further includes providing the classifier with an interior divider assembly defining at least one inclined channel. The divider assembly typically includes a plurality of substantially parallel dividers separating the classifier into multiple channels having a substantially equal internal volume. A hydraulic classifier for separating particles having a mean particle size of from about 2-7 ?m in accordance with the present method is provided also.

Abstract: A novel method for producing fly ash material with a range of particle sizes from about 2.0 to about 4.0 &mgr;m is provided utilizing superplasticizers. The method produces fly ash material suitable for use as filler material in the plastics industry and super pozzolan for the concrete industry.

Abstract: A method for improving the pozzolanic character of fly ash includes the steps of first hydraulically classifying and then flotation separating the fly ash in order to reduce particle size distribution and remove carbon. The method also includes the steps of spiral concentrating separated coarse particles to recover iron, pyrite and marcasite and screening the fly ash to remove ultra-light carbon and plant debris.