United States Patent Application: 0130190165
We're introducing herein a topic and subject related to the productive use and consumption of Coal Ash that we'll only be addressing sporadically, if at all, in the future.
And, we'll have to use a pretty broad brush to cover it, both because of our own personal insufficiencies and because we suspect that the issue is not well known, if at all, among even construction professionals.
We have been blessed with some gratefully-received knowledgeable advisement on the technicalities; but, again, our own limitations will limit the depth of discussion.
However, since, as recently acknowledged by the United States House of Representatives, as reported just this past July 25, 2013, by the Washington Times, in "House Trims EPA's Powers Over Coal Ash":
House trims EPA's powers over coal ash - Washington Times; "With bipartisan support, the House on Thursday passed legislation giving states the lead role in regulating coal ash and stopping the Environmental Protection Agency from labeling the material as hazardous. “States, utilities and hundreds of thousands of workers in the recycling industry have been waiting in limbo for a resolution. This bill meets those needs,” said Rep. Fred Upton, Michigan Republican, who is House Energy and Commerce Committee chairman. The bill, which passed by a vote of 265 to 155 and garnered the support of 39 Democrats, gives each state control over how coal ash is managed and disposed of. Coal ash is the leftover byproduct when coal is burned, and (is) often safely recycled and used in concrete, cement, wallboard, roofing materials and other products";
Coal Ash can be, should be, and is in some cases being, viewed and treated as a valuable raw material for the manufacture of certain commodity construction products, we think it important to emphasize the value of Coal Ash, and to illustrate the broad utility it can provide, in such applications.
In brief, we'll assume that most are familiar in at least general terms with Portland-type cement, and Portland cement concrete, both of which, as seen for example 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 by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock (and) wherein said source of aluminum and iron comprises fly ash"; and, in:
West Virginia Coal Association | Fly Ash and Desulfurization Waste Make "Premium" Cement | Research & Development; concerning: "United States Patent Application 20060201395 - Blended Fly Ash Pozzolans; 2006; (Presumed eventual Assignee of Rights: Ash Grove Cement Company, Kansas); Abstract: Novel premium blended pozzolans for use with hydraulic cement are created by intergrinding an ASTM Class F or Class C coal fly ash and a source of calcium sulfate, such as gypsum ... . ... Alternately, a novel concrete composition can be formed using the blended pozzolan with a hydraulic cement, aggregate and water so as to produce a concrete having improved strength, ASR mitigation, improved sulfate resistance and lowered permeability. The novel pozzolans not only reduce production costs by decreasing fuel and raw material consumption per ton of cement, but they also use by-product waste materials from another industry to create a premium product for the construction industry"; and, in:
West Virginia Coal Association | Coal Ash Concrete More Durable, Resists Chemical Attack | Research & Development; concerning, in part: "United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar; 1998; Assignee: New Jersey Institute of Technology; 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 while maintaining acceptable compressive strength properties. ... The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand";
can be advantageously made in ways that consume significant amounts of Coal Ash.
Moreover, as seen in:
West Virginia Coal Association | 1951 Coal Ash Bricks | Research & Development; concerning: "United States Patent 2,576, 565 - Ceramic Product and Method of Making the Same; 1951; Assignee: G. and W.H. Corson, Inc., PA; The present invention relates to a ceramic product and to the body from which it may be produced and, more particularly, it relates to a ceramic product comprising the waste ash material obtained from coal burning industrial power and other plants, and to the method of producing same. The product of the present invention, as will hereinafter appear, possesses properties at least equivalent to those of conventional clay or shale ceramic products and, therefore, may be used as a substitute therefor; for example, the product of the present invention may in the form of a brick, a tile or a pipe. One object of the present invention is to provide a ceramic product of advantageous properties, making it especially suitable for use as a structural material. Another object is to provide a ceramic product which, because of its properties, is available for use for the various purposes where conventional clay or shale ceramic products are now used, including the use of the product in the form of a brick, a tile, a sewer pipe, and the like. A further object of the present invention is to provide a ceramic product by the utilization of waste material produced by the burning of coal in power and industrial plants"; and, in:
West Virginia Coal Association | USDOE and WVU Sponsor Illinois Coal Ash Brickmaking | Research & Development; concerning: "Combustion Byproducts Recycling Consortium Project Number: 02-CBRC-M12; Manufacturing Fired Bricks With Class F Fly Ash from Illinois Basin Coals; 2006; Illinois State Geological Survey (and) University of Illinois Urbana-Champaign; Support for this project provided in part by the US Department of Energy, National Energy Technology Laboratory, through its Cooperative Agreement (No. DE-FC26-998FT40028) with the West Virginia University Research Corporation, Combustion Byproducts Recycling Consortium (CBRC). The cooperation and in-kind contributions provided by the Colonial Brick Company, Cinergy PSI, and the Indiana Geological Survey are valued and appreciated. The purpose of this project was to determine if Class F fly ash produced by one of the power generation stations of the Cinergy PSI is a viable raw material for brick production at a nearby brick plant. This power generation station is located in Indiana near the Illinois border, and burns Illinois Basin coals from both Illinois and Indiana.
A technical feasibility assessment was conducted for this process, which uses fly ash as a substitute for part of the clay and shale used in making conventional bricks. Commercial-scale production demonstrations, which included extrusion and firing evaluations, have produced a total of about 4,000 commercial-size paving bricks and 8,000 commercial-size three-hole building bricks for evaluation. The paving bricks contained 20% by volume of fly ash, and the building bricks contained 20%, 30%, or 40% by volume (about 37% by weight) of fly ash. These final products have met or exceeded ASTM standard specifications for pedestrian and lightweight traffic paving bricks and for building bricks of a severe weather grade. An economic evaluation indicated that it would be economically feasible for the brick plant to use the fly ash as a raw material in commercial brick production. Also, the environmental feasibility study showed that, similar to the regular commercial brick, the fly ash containing bricks are environmentally safe construction products";Coal Ash can also be used to great advantage as a raw material, as a replacement for some or all of the conventional mined clays, in the making of fired ceramic-type construction products, such as bricks.
As most at least instinctively realize, there are significant and useful differences between what we think of as "cement" or "concrete", and kiln-fired ceramic products, again like bricks, or, like what are know as "clay" drainage pipes and roof tiles.
Ceramic products, for instance, are usually much more resistant to chemicals and corrosion than are their Cement or Concrete-based counterparts, and can be, simply, in several ways, "stronger".
However, the fact that ceramic products must be molded into shape, and then fired and fused at a central, stationary facility, rather than being "poured" into shape, and then cured, like cement, at the end point of use, limits their ultimate utility. Further, the energy consumed during the lengthy ceramic firing process leads to conventional ceramic products having a large energy cost embodied within them.
As it happens, perhaps little known to many, even in the construction trades, there is what might be thought of as a class of materials intermediate in qualities between conventional cement or concrete, and ceramics.
Like cement and ceramics, they can be molded into any shape. But, like cement, they can be poured into shape and cured, or hardened, at their point of use. And, like ceramics, their final chemical composition is a more ordered crystalline structure that renders them more durable and more chemically-resistant.
Specifically, they are known as "chemically-bonded phosphate ceramics". The term "phosphate" is most often included, since phosphoric acid is most often, as we will see, utilized in their formulation. But, they are also at times just referred to as "phosphate ceramics", or "phosphate cement", or "chemically-bonded ceramics".
And, as can be learned via:
http://www.netl.doe.gov/KMD/
Argonne National Laboratory; (USDOE); IL; During our effort to stabilize contaminated ashes in the U. S. Department of Energy's (DOE's) complex by a novel chemically bonded phosphate ceramic, we formulated a high strength concrete made of benign ashes (such as fly ash and coal bottom ash) that may be useful for specialized applications in construction industry. ... (It) sets into a hard mass in (less than an hour, and, with) a typical ash loading of 60 weight percent it has a strength of (more than)12,000 psi. The micro structure of the concrete is glass-crystalline. This product is not very sensitive to the ash composition. Unlike in portland cement, it is unaffected by the unburnt carbon in the ash or to any Cl ions, and thus a wide variety of combustion products may be incorporated to develop this product. The material cost is generally 50% higher than portland cement, but processing advantages, such as faster setting, setting in cold environment, and self binding characteristics may off-set some of the costs, or improved properties may justify slightly higher costs for specialized product development"; and:
http://web.anl.gov/
"'Chemically Bonded Phosphate Ceramics: Cementing the Gap Between Ceramics, Cements and Polymers'; Argonne National Laboratory (USDOE); An overview of chemically bonded phosphate ceramics (CBPCs), that fill the gap between cements and conventional ceramics, is provided. CBPCs are synthesized by chemical reactions, most of them at ambient conditions, and hence are most useful in high volume applications. These applications include stabilization of hazardous and radioactive wastes, various structural materials applications, including road repair, oil well cements, and architectural products. The products are mainly magnesium and iron-phosphate ceramics";
whether we call them chemically-bonded phosphate cements or phosphate ceramics, they have, as will we see further on, some specific utility which the USDOE is, or was, interested in exploiting.
And, as confirmed herein by the University of California, they can be made from, as the predominate raw material, Coal Ash.
Comment follows excerpts from the initial link in this dispatch to:
"United States Patent Application 20130190165 - Chemically Bonded Ceramics Based on Fly Ash
Patent US20130190165 - Chemically bonded ceramics based on fly ash - Google Patents
CHEMICALLY BONDED CERAMICS BASED ON FLY ASH - The Regents of the University of California
Date: July 25, 2013
Inventors: Henry Colorado, IL, and Jenn-Ming yang, CA
Assignee: The University of California
Abstract: Chemically bonded ceramics and manufacturing processes are described. In one aspect, a manufacturing process of a chemically bonded ceramic is carried out by:
(1) combining an acidic liquid and Fly Ash to form a mixture; and:
(2) curing the mixture to form the chemically bonded ceramic. The Fly Ash corresponds to at least a majority by weight of solids combined with the acidic liquid to form the mixture.
Claims: A manufacturing process of a chemically bonded ceramic, comprising: combining an acidic liquid and Fly ash to form a mixture, wherein the Fly ash corresponds to at least a majority by weight of solids combined with the acidic liquid to form the mixture; and curing the mixture to form the chemically bonded ceramic.
(And) wherein the Fly Ash corresponds to at least 90% by weight of solids combined with the acidic liquid to form the mixture.
The manufacturing process ... wherein the acidic liquid and the Fly ash are combined in a weight ratio in a range of 0.25:1 to 2:1 (and) wherein the acidic liquid corresponds to an aqueous phosphoric acid solution.
The manufacturing process ... wherein curing ... is carried out at a temperature up to (50 to) 110 C.
A manufacturing process of a chemically bonded ceramic, comprising: forming an aqueous mixture including an acid and water in a combined amount corresponding to 20% to 67% by weight of the aqueous mixture, and Fly Ash in an amount corresponding to at least 90% of a remaining weight of the aqueous mixture; and reacting the acid and the Fly Ash in the aqueous mixture to form the chemically bonded ceramic.
The manufacturing process ... further comprising: providing an aqueous solution of the acid; and combining the aqueous solution and the Fly Ash to form the aqueous mixture, wherein the Fly Ash corresponds to at least 90% by weight of solids combined with the aqueous solution to form the aqueous mixture.
The manufacturing process ... wherein the acid corresponds to phosphoric acid (and) wherein the aqueous mixture further includes borax in an amount up to 1% by weight of the aqueous mixture.
(As can be learned via:
Phosphoric acid - Wikipedia, the free encyclopedia; "Phosphoric acid ... has a wide variety of uses, including as a rust inhibitor, food additive, ... fertilizer feedstock, and component of home cleaning products";
the needed "phosphoric acid" is cheap; we make a lot of it; and, we use it in a lot of things, like soda pop and fertilizer. We will note, too, that we have in the course of our reportage touched on this sort of technology once or twice previously, but not in depth. And, without referencing our past reports, although we might again address it in the future, we will note that these same sorts of Fly Ash reactions can be effected as well with Citric Acid. Phosphoric Acid is much less expensive; but, Citric Acid and it's derivatives do offer perhaps some benefits relative to sustainability and, indirectly, botanical CO2 recycling.)
A chemically bonded ceramic ... formed by reacting phosphoric acid and Fly ash.
Description and Field: The invention generally relates to ceramics and, more particularly, to chemically bonded ceramics based on Fly Ash.
High temperature manufacturing processes contribute to global warming, and this contribution is particularly significant in the processing of cementitious and ceramic materials.
Manufacturing of conventional ceramics typically involves high temperatures during at least part of a manufacturing process, which is undesirable because of increased cost and negative environmental impact. Sintered ceramics have been used for thousands of years by humans, and even today are the subject of intense research mainly at high temperatures. However, sintering can involve a significant amount of energy, and the process can be expensive at large manufacturing scales. An alternative to sintering is chemical bonding as in hydraulic cements, which allows these materials to be inexpensively manufactured in high volume production. Although sintered ceramics typically are expensive compared to hydraulic cements, ceramics in general can have higher mechanical strength, corrosion resistance, and temperature stability. It is desirable to develop materials that have properties in between sintered cements and hydraulic ceramics to fill the gap between these materials.
It is against this background that a need arose to develop the chemically bonded ceramics and manufacturing processes described herein.
Summary: One aspect of this disclosure relates to a manufacturing process of a chemically bonded ceramic. In one embodiment, the manufacturing process includes:
(1) combining an acidic liquid and Fly Ash to form a mixture; and:
(2) curing the mixture to form the chemically bonded ceramic.
The Fly Ash corresponds to at least a majority by weight of solids combined with the acidic liquid to form the mixture.
In another embodiment, the manufacturing process includes:
(1) forming an aqueous mixture including:
(i) an acid and water in a combined amount corresponding to 20% to 67% by weight of the aqueous mixture, and
(ii) Fly Ash in an amount corresponding to at least 90% of a remaining weight of the aqueous mixture; and:
(2) reacting the acid and the Fly Ash in the aqueous mixture to form the chemically bonded ceramic."
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There is of course a bit more to it, mostly in terms of allowable variances in relative composition and processing conditions. And, there is some data on physical properties. In sum, the stuff is strong and resists chemical attack. It's also more impervious to water flow than a standard Portland Cement Concrete might be.
And, perhaps interestingly, as seen in:
West Virginia Coal Association | Australia and California Synthesize Coal Ash Microspheres | Research & Development; concerning: "United States Patent 7.666.505 - Synthetic Microspheres Comprising Aluminosilicate and Methods of Making Same; 2010; Assignee: James Hardie Technology Limited, Ireland;Abstract: A synthetic microsphere having a low alkali metal oxide content and methods of forming the microsphere and its components are provided. The synthetic microsphere is substantially chemically inert and thus a suitable replacement for natural cenospheres, particularly in caustic environments such as cementitious mixtures. The synthetic microsphere can be made from an agglomerate precursor that includes an aluminosilicate material, such as fly ash, ... The synthetic microsphere is produced when the precursor is fired at a pre-determined temperature profile so as to form either solid or hollow synthetic microspheres depending on the processing conditions and/or components used. The synthetic microsphere ... wherein the synthetic substantially spherical wall further comprises a binding agent (and) wherein the binding agent is selected from ...ultra fine fly ash, Class C fly ash, Class F fly ash, (etc.), and combinations thereof. The synthetic microsphere ... further comprising a wall thickness of between about 1 to 100 microns (and) the average particle diameter of the microsphere is between about 30 and 1000 microns (and) wherein the aluminosilicate material is derived from fly ash. These embodiments have been developed primarily to provide a cost-effective alternative to commercially available cenospheres. One of the characterizing features of cenospheres is their exceptionally high chemical durability. ... (And) cenospheres have proven to be especially useful in building products and in general applications where they may come into contact with corrosive environments where high chemical durability is desirable. It is particularly advantageous that the synthetic microspheres can be prepared from fly ash. Synthetic microspheres according to the present invention may be used as fillers in composite materials, where they impart properties of cost reduction, weight reduction, improved processing, performance enhancement, improved machinability and/or improved workability. More specifically, the synthetic microspheres may be used as fillers in polymers (including thermoset, thermoplastic, and inorganic geopolymers), inorganic cementitious materials (including material comprising Portland cement, lime cement, alumina-based cements, plaster, phosphate-based cements";
such "Chemically Bonded" phosphate "Ceramics Based on Fly Ash", keeping in mind that with chemically bonded ceramics it's not really incorrect to call them "cements", are compatible with and can have some beneficial properties imparted to them by the incorporation of another solid Coal Combustion Byproduct.
And, if you were wondering why our USDOE was, as in our introductory comments and references, so specifically interested in such a seemingly useful impermeable, chemically-resistant and strong Cement-Ceramic that could be poured and set in the field, one clue is provided in our above-cited "Chemically Bonded Phosphate Ceramics: Cementing the Gap Between Ceramics, Cements and Polymers'; Argonne National Laboratory (USDOE); An overview of chemically bonded phosphate ceramics (CBPCs), that fill the gap between cements and conventional ceramics, is provided. ... CBPCs are synthesized by chemical reactions, most of them at ambient conditions, and hence are most useful in high volume applications. ... These applications include stabilization of hazardous and radioactive wastes".
That utility is further confirmed via:
http://web.anl.gov/techtransfer/Available_Technologies/Ceramicrete/pdfs/CRC5.pdf; concerning: "'Chemically Bonded Phosphate Ceramics for Stabilization and Solidification of Mixed Waste'; Argonne National Laboratory; This chapter reviews a novel chemically bonded phosphate ceramic technology developed at Argonne National Laboratory to stabilize low-level radioactive and transuranic mixed waste streams within the U.S. Department of Energy (DOE) complex. This cement-like technology, which can be used to treat solids, liquids, and sludges by micro- and/or macro-encapsulation and chemical immobilization, is based on chemical reaction between phosphate anions and metal cations to form a strong, dense, and durable matrix that stores the hazardous and radioactive contaminants as insoluble phosphates and microencapsulates insoluble radioactive components. In this chapter, we discuss the thermodynamic basis of phosphate stabilization and present several case studies to demonstrate the effectiveness of the process in a wide variety of actual waste streams that include low-level mixed ash, transuranics, fission products, radon-emanating wastes, salt solutions, and heterogeneous mercury-containing debris. These case studies demonstrate that the waste forms are not only stable in groundwater environments, but also are non-ignitable and hence safe for storage and transportation. The process has been made very versatile and thus can be used to treat wide-ranging chemical species such as those in higher oxidation states, as well as very highly
soluble salt solutions. To attain this versatility, we have developed reduction methods and coupled
chemical immobilization with macroencapsulation. An independent study has found that this
room-temperature phosphate stabilization process is one of the most economical processes available to treat low-level mixed waste within the DOE system".
And, thus, a strong, impermeable product made in an energy-efficient process from the relatively innocuous solid wastes arising from our economically essential use of Coal in the generation of truly abundant and truly affordable electric power could be used to save us, and our environment, from the truly horrific wastes arising from our misguided use of dangerous, Chernobyl/Three Mile Island-type nuclear facilities to generate electricity that could, in some ways, wind up being so expensive we could never, really, afford to pay the price.
But, we're certain some other valuable uses could be found for it, as well; with all of those uses further confirming that there is a lot of value in Coal Ash. Those of us in US Coal Country just need to apply ourselves to the task of getting educated about the potentials.