United States Patent: 6054074

In a dispatch now accessible on the West Virginia Coal Association's web site, via the link:

West Virginia Coal Association | Consol Converts Coal Ash to Concrete Aggregate | Research & Development; we made report of:

"United States Patent 5,364,572 - Process for Making High-Strength Synthetic Aggregates; 1994; Inventors: Muh-Cheng Wu and George Wasson; Assignee: Consolidation Coal Company, Pittsburgh; Abstract: A process for making high-strength synthetic aggregates from ... coal combustion ash ... (that) have suitable unit weight, grain size distribution, (specified) abrasion and soundness indices for use as coarse aggregates in road base, asphalt concrete and Portland cement concrete in road construction (and) synthetic aggregates from ... spray dryer ashes (that) have suitable unit weight, grain size distribution for use as coarse lightweight aggregates in concrete masonry units";

we documented that our local Consolidation Coal Company had demonstrated that Coal combustion wastes could be made into strong, coarse aggregate for use in Portland Cement Concrete, and other applications.

And, we note that such potentials for Coal Ash have also been explored and confirmed by others, as we reported, for just one example, in:

West Virginia Coal Association | Wyoming Converts Coal Ash to Construction Aggregates | Research & Development; concerning:

"United States Patent 6,334,895 - Producing Manufactured Materials from Coal Combustion Ash; 2002; Assignee: The University of Wyoming Research Corporation; Abstract: This invention discloses a system for cold bond processing of combustion ash which enhances various characteristics of the resulting cured consolidated combustion ash materials. Specifically, the invention relates to processing techniques which enhances both density and strength of the of the consolidated combustion ash materials. The invention also relates to processing techniques which control various chemical reactions which assure that certain types of minerals are formed in the proper amounts which results in a cured consolidated combustion ash material which has greater dimensional stability and enhanced resistance to degradation. Embodiments for both normal weight and light weight combustion ash aggregates are disclosed which meet various ASTM and AASHTO specifications".

Keep in mind that such processes for making coarse aggregate, for use in making concrete out of cement,  and in other applications, out of Coal Ash, represent potentials for the use of Coal Ash in concrete above and beyond those we've also documented, as, for instance, in:

West Virginia Coal Association | Pittsburgh Converts Coal Ash and Flue Gas into Cement | Research & Development; concerning: "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste; 1998; Assignee: Dravo Lime Company, Pittsburgh, PA; Abstract: Cement is produced (from) a mixture of a flue gas desulfurization process waste product (and) fly ash";

wherein the Portland-type cement itself can be made from Coal Combustion Byproducts; and, in:

West Virginia Coal Association | Coal Ash Concrete More Durable, Resists Chemical Attack | Research & Development; concerning: "United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar; 1998; Assignee: New Jersey Institute of Technology, Newark, NJ; Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance";

wherein Coal Fly Ash can be added to Cement, as a fine, reactive aggregate, replacing some of the sand otherwise used in the blending of Concrete, which practice, as specified by the New Jersey Institute of Technology, results in a final, cured product with improved resistance to chemical attack.

In any case, we learn herein that Consol continued to improve their technology for manufacturing construction aggregates from Coal Utilization Byproducts, as seen in excerpts from the initial link to:

"United States Patent 6,054,074 - Manufactured Aggregates from Coal Combustion Byproducts

Date: April, 2000

Inventors: Muh-Cheng Wu and George Wasson, PA

Assignee: Consol, Inc., Pittsburgh

Abstract: This is a method of producing manufactured aggregates from coal combustion by-products having sulfur. Recycle fines containing calcium hydroxide, an aluminum-containing material, and water are mixed together to form a feed mix which is agglomerated into an agglomerated product. The agglomerated product is combined with curing fines which contain calcium oxide which together form a blended mix. The blended mix is cured using the moisture in the blended mix which is used to exothermally hydrate the calcium oxide in the blended mix to form calcium hydroxide and which autogenically provides the required heat for curing and converts the calcium oxide in the blended mix to a dry calcium hydroxide-containing material to form aggregate products and dry fines. The aggregate products are separated from the dry fines, the dry fines are recycled to the mixing step and the aggregates are taken and used as a useful product for other purposes.

Claims: Method of producing manufactured aggregates from a combustion by-product comprising: 

(a) providing combustion by-products which contain sulfur; 

(b) providing recycle dry fines containing calcium hydroxide (Ca(OH)2); 

(c) providing an aluminum-containing material; 

(d) providing water; 

(e) mixing the recycle dry fines containing calcium hydroxide, combustion by-product, aluminum-containing material, and the water to form a feed mix; then

(f) agglomerating the feed mix into an agglomerated product; then 

(g) combining the agglomerated product with curing fines which contain calcium oxide and which produces a blended mix; then 

(h) curing the blended mix to form the aggregates and create recycle dry fines for recycling, during which moisture in the blended mix exothermally hydrates calcium oxide in the blended mix to form a dry calcium hydroxide-containing material and autogenically provides all of the required heat for curing and no external heat is required ... . 

The method as recited in claim 1 wherein the combustion by-product comprises wet flue gas desulfurization sludge and the aluminum-containing material comprises pulverized coal fly ash.

(Note, that, as in "autogenically provides all of the required heat for curing and no external heat is required", the proper blend of specified raw materials react together exothermically; and, all the heat energy needed to drive the process to completion is generated within the process itself. We don't have to supply, after preparation of the ingredients, any appreciable amounts of energy, beyond that needed for materials handling, to drive the process of  "United States Patent 6,054,074 - Manufactured Aggregates from Coal Combustion Byproducts" forward.)

The method ... wherein the sulfur and aluminum-containing material comprises dry flue gas desulfurization by-product. 

The method ... wherein the combustion by-product comprises wet flue gas desulfurization sludge and the aluminum-containing material comprises pulverized coal fly ash ... wherein the product is lightweight aggregate.

Background and Field: Aggregates, traditionally made from natural and crushed stone and sand, constitute about 80% by volume of concrete in structural materials and road construction. The consumption of natural aggregates in the United States is well over one billion tons per year. This invention relates to a process for producing manufactured aggregates from coal combustion by-product. The manufactured aggregates meet standard commercial specifications for road, lightweight and concrete aggregates, making them suitable for use in construction and agricultural applications. The replacement of natural aggregates with aggregates manufactured from coal combustion by-product could provide an opportunity for the high-volume use of and substantially expand the market for coal combustion byproduct."

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We'll close our excerpts there to emphasize the point:

According to Consolidation Coal Company, in a statement affirmed by a technical branch of our United States Government:

"The consumption of natural aggregates in the United States is well over one billion tons per year".

And, again according Consol, and as affirmed by our US Government, in the Disclosure of our subject:

"United States Patent 6,054,074 - Manufactured Aggregates from Coal Combustion Byproducts";

and, in the precedent:

"United States Patent 5,364,572 - Process for Making High-Strength Synthetic Aggregates; 1994; Inventors: Muh-Cheng Wu and George Wasson; Assignee: Consolidation Coal Company, Pittsburgh; Abstract: A process for making high-strength synthetic aggregates from ... coal combustion ash";

we can make perfectly acceptable substitutes for nearly all of those "natural aggregates" out of the solid residua arising from our essential use of Coal in the generation of economical electric power.

Further, according to the American Coal Ash Association, via:

ACAA - Promoting & Advancing Coal Combustion Products; and:

Coal Ash Facts provides important facts about coal ash including generation, handling, safety, environmental concerns and its:

In 2007, the United States produced 131 million tons of coal combustion products, "CUB's", or "CCB's".

Which means that, on a per-year basis, if literally all of our yearly production of Coal Utilization Byproducts were turned, via the processes of Consol's "United States Patent's 6,054,074" and "5,364,572", into construction aggregates, we couldn't satisfy or fill even 20% of the market for such aggregates.

Demand would far exceed supply, and we wouldn't have to landfill or otherwise dispose of any of our solid Coal Utilization Byproducts.

Keep in mind:

That market demand for construction aggregates does not include the market for Fly Ash in the making of the Cement itself, as exemplified in the above-cited:

"United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste; 1998; Assignee: Dravo Lime Company, Pittsburgh, PA; Abstract: Cement is produced (from) a mixture of a flue gas desulfurization process waste product (and) fly ash";

or, as a fine aggregate to be added to the Cement, as in the above-cited:

"United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar; New Jersey Institute of Technology; The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications".

If all of those potentials were even partly realized, we wouldn't have enough Coal Utilization Byproducts (CUB's) to satisfy any ways near all of them.

We might, in fact, be tempted to go out and dig up and reclaim some of our older Coal Fly Ash; that is, Fly Ash and other CUB's that were previously land-filled, or otherwise buried or stockpiled, in order to supply that huge market.

And, in fact, as we will document in reports to follow, it has been proposed, and technologies and procedures have been developed, to accomplish exactly that.


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