United States Patent: 5521132
In a recent dispatch, we documented that Coal Ash can be used, as a substitute for the traditional raw materials, in the making of Ceramics; which is an entirely different class of materials than the Cement and Concrete that, we have more than thoroughly documented, can be made in such property-enhancing and energy-efficient ways from Coal Ash.
The ceramics we were talking about, in:
West Virginia Coal Association | Coal Ash Makes Better Bricks | Research & Development; concerning:
"US Patent Application 20120031306 - Bricks and Method of Forming Bricks with High Coal Ash Content;
2012; (Presumed Assignee: Belden Brick Company, OH); Abstract: There is provided an apparatus and process for manufacturing a brick or paver with a high content of coal ash (ranging from 60% to 100% coal ash or fly ash) so that a waste product (coal ash, and more particularly Class F coal ash) from a coal-fired power plant is incorporated into a building product (high content fly ash brick or paver). A fly ash brick comprising, in the fired state, up to 80% fly ash. The brick (can be) an ash-based paver that exhibits a useful life of at least 2 times that of a concrete paver manufactured from Portland cement and having the same dimensions";
even though just fired "brick", as seen in:
Brick - Wikipedia, the free encyclopedia; "A brick is a block, or a single unit of a ceramic material used in masonry construction"; and, in:
Ceramic - Wikipedia, the free encyclopedia; "A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the noncrystalline glasses. (Examples:) bricks, pipes, floor and roof tiles; Refractories, such as kiln linings, gas fire radiants, steel and glass making crucibles; Whitewares, including tableware, cookware, wall tiles, pottery products and sanitary ware; Technical, is also known as engineering, advanced, special, and in Japan, fine ceramics. Such items include tiles used in the Space Shuttle program, gas burner nozzles, ballistic protection, nuclear fuel uranium oxide pellets, biomedical implants, coatings of jet engine turbine blades, ceramic disk brakes, missile nose cones, bearing (mechanical). Frequently, the raw materials do not include clays";
are, nonetheless, ceramics; and, are closely related to both your grandma's fine china and the necessary fixtures in your bathroom.
And, as seen in the above excerpts from the Wikipedia, ceramics have a wide variety of other uses, ranging from the prosaic to the somewhat glamorous, i.e., "tiles used in the Space Shuttle program".
Herein, we see that our own United States Navy, the same one's who, as seen in:
US Navy 2008 CO2 to Synfuel | Research & Development; concerning: "US Patent 7,420,004 - Producing Synthetic Liquid Hydrocarbon Fuels; 2008; Assignee: The USA, as represented by the Secretary of the Navy; Abstract: A process for producing synthetic hydrocarbons that reacts carbon dioxide, obtained from seawater or air, and hydrogen obtained from water";
told us before the election of President Obama that we can efficiently recycle Carbon Dioxide into liquid hydrocarbon fuels, and, who, as well, as in:
US Navy Coal + H2O = Low Cost Methanol | Research & Development; concerning: "United States Patent 4,476,249 - Low Cost Method for Producing Methanol; October, 1984; Assignee: The Johns Hopkins University, Baltimore; The Government has rights in this invention pursuant to Contract N00024-78-C5384 awarded by the Department of the Navy. Abstract: Method for producing low cost methanol. A source of carbon is provided to an OTEC plant or plantship which is processed to produce carbon monoxide which is reacted with hydrogen to produce methanol. The oxygen and hydrogen are obtained from the electrolysis of water with the required energy supplied by ocean thermal energy conversion. Method of producing low cost methanol from coal';
told us before the reelection of President Reagan that we can use environmental energy to convert Coal into a valuable liquid fuel;
told us a little more than a decade and half ago that we can consume and utilize Coal Ash as a raw material in the making of ceramics.
Comment follows, and is inserted within, excerpts from the initial link in this dispatch to:
"United States Patent 5,521,132 - Ash-based Ceramic Materials
(Ash-based ceramic materials - The United States of America as represented by the Secretary of the Navy)
Date: May, 1996
Inventors: Inna Talmy, et. al., MD and VA
Assignee: The USA as Represented by the Secretary of the Navy
Abstract: A ceramic material made from raw coal fly ash or raw municipal solid waste fly ash and (1) sodium tetraborate or (2) a mixture of sodium tetraborate and a calcium containing material that is triple superphosphate, lime, dolomitic lime, or mixtures thereof.
(First, the "lime" would just be Calcium Oxide, CaO, as made, via calcination, in a cement kiln, as per the equation CaCO3 + Heat = CaO + CO2, from plain old limestone. Nearly all limestone is also comprised of at least some Magnesium Carbonate, MgCO3, and is known, depending on how much of the MgCO3 there is, as "dolomite", or "dolomitic limestone". Such limestone, when calcined in a cement kiln, would yield the above-specified "dolomitic lime". We do confess, that, since Fly Ash can replace nearly all of the raw materials in a cement-making process, it seems strange to us that what is, in essence, cement, would be required to convert Fly Ash into a ceramic. But, the raw materials are plentiful and inexpensive. And, as in:
Borax ( Na2B4O7. 10H2O ) - Sodium Borate - Occurrence, Discovery and Applications; and:
Borax - Wikipedia, the free encyclopedia; "Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and salt of boric acid"; and:
Monocalcium phosphate - Wikipedia, the free encyclopedia; "Superphosphate is a fertilizer produced by the action of concentrated sulphuric acid on powdered phosphate rock";
even the ones that sound a little exotic are pretty darned common. Further, as can be learned via:
Ceramics; "Borates have been an essential ingredient in ceramic glazes ... for centuries";
there isn't anything revealed herein that's revolutionary. The "envelop" is not being pushed.)
Claims: A process for producing a ceramic material comprising:
A. mixing raw fly ash particles that are raw coal fly ash particles, raw municipal solid waste fly ash particles, or mixtures thereof with a flux material that is sodium tetraborate or a mixture of sodium tetraborate and a calcium-containing material that is triple superphosphate, lime, dolomitic lime, or mixtures thereof;
B. forming the mixture of raw fly ash particles and flux material into a green body;
C. heating the green body up to a temperature just below the melting point of sodium tetraborate to drive off water and other volatiles and to burn off carbon to produce an intermediate body in which the raw fly ash particles of the green body have been converted to residual fly ash particles;
D. converting the intermediate body into a ceramic body by firing the intermediate body at a temperature of from just above the melting point of sodium tetraborate to about 1000.degree. C. until the sodium tetraborate or mixture of sodium tetraborate and calcium-containing material melts to form a molten flux which reacts with chemicals in a portion of the residual fly ash particles to produce water-insoluble reaction products which bind the residual fly ash particles together; and
E. cooling the ceramic material body to ambient temperature;
wherein the raw fly ash particles, sodium tetraborate, and calcium-containing material if present are mixed in step A in amounts that will produced an intermediate body in step C that consists essentially of from about 4 to about 10 weight percent of anhydrous sodium tetraborate, from zero about 5 weight percent of anhydrous calcium-containing material with the remainder of the intermediate body being residual fly ash particles formed from the removal of water and other volatile materials and the burning off of carbon from the raw ash particles used in the mixture of step A.
The process wherein the flux material in step A is sodium tetraborate.
The process ... wherein raw the fly ash used in step A is raw class C coal fly ash.
The process ... wherein the flux material in step A is a mixture of sodium tetraborate and a calcium-containing material.
The process ... wherein the calcium-containing material is triple superphosphate.
The process ... wherein the calcium-containing material is a mixture of lime and dolomitic lime.
The process ... wherein the raw fly ash used in step A is raw coal fly ash.
The process ... wherein the raw fly ash used in step A is raw class F coal fly ash.
The process ... wherein the raw fly ash used in step A is raw class C coal fly ash.
The process ... wherein the raw fly ash used in step A is raw municipal solid waste fly ash.
(They do provide guidelines concerning how much of each component is to be used; and, without reproducing the Navy's numbers, our read of it is that Coal Ash will make up at least eighty percent of the final ceramic blend, and could make up, as we read it, 90%, or a little more. The other materials are essentially just "fluxes" added to help things melt and flow together more easily. - JtM)
The process ... wherein ... the intermediate body is heated at a temperature of from 750 to 950 C.
The process ... wherein in step A the raw fly ash particles are mixed with a suspension of lime particles, dolomitic lime particles, or mixtures thereof in an aqueous solution of sodium tetraborate which is at a temperature of from about 60C to the boiling point of the aqueous solution at ambient pressure and the resulting mixture is then cooled to ambient temperature ... (and) the moisture content of the resulting mixture is reduced by evaporation.
A ceramic material that is produced from a precursor mixture of ... dry residue fly ash particles that were produced by removing essentially all carbon and volatile materials from raw coal fly ash particles or raw municipal solid waste fly ash particles, or mixtures thereof ... ;
(Since they prefer "all carbon" to be removed from the Fly Ash, we remind you of our report concerning:
West Virginia Coal Association | Virginia Converts Coal Ash to Cash | Research & Development; about: "South Carolina Electric and Gas Successful Application of Carbon Burn-Out (CBO); 1999 International Ash Utilization Symposium; Center for Applied Energy Research, University of Kentucky; South Carolina Electric and Gas Company; Progress Materials, Inc.; and, Southeastern Ash Co., Inc.; CBO combusts residual carbon in fly-ash, producing a very consistent, low-carbon, high-quality pozzolan. Extensive concrete testing has been and continues to be undertaken in order to demonstrate the superior characteristics of very low-carbon Class F fly ash from Carbon Burn-Out. An important feature of Carbon Burn-Out is heat recovery from the residual carbon's combustion. Heat is recovered from both the flue gas and the hot product ash. This recovered heat is returned to Wateree Station by heating a portion of the power plant's process stream (which) increases the quantity of steam available to the turbine-generator".
Such "Carbon Burn-Out" processes for Coal Ash, wherein the Coal Ash product is improved by removing residual Carbon while, at the same time, some energy content is recovered, are actually well-established technologies, which we will attempt to do a better job of explaining in future reports.)
The ceramic material ... wherein the residual fly ash particles in the precursor mixture were produced from raw class C coal fly ash particles (and/or) raw class F coal fly ash particles.
Background: Coal fly ash has complex chemical composition containing up to 80 weight percent of SiO2 and Al2O3, with Fe2O3, CaO, MgO, Na2O, K2O, SO3 and other oxides as the remainder.
The chemical composition significantly varies depending on coal deposits and power plant operating parameters. In addition to coal fly ash, large quantities of municipal solid waste (MSW) ash are being produced by the incineration of municipal trash, garbage, and even sewage solids.
Fly ash has been used in cement as a substitute for shale; in concrete as a substitute for cement and sand, and as aggregates; in road construction as a filler to bitumen, and as a substitute for sand in the foundation layer; in bricks as a substitute for clay; for soil stabilization; etc. These prior art uses do not lead to massive consumption of fly ash because the ash is usually only a minor component in these composites. It would be desirable to provide processes and products that would use fly ash as the major component, preferably in amounts exceeding 85 weight percent.
(The above assertion that "prior art uses do not lead to massive consumption of fly ash because the ash is usually only a minor component in these composites" is simply mistaken; or, it is deliberate hyperbole for the sake of the original patent application. As seen in our introductory reference to: "US Patent Application 20120031306 - Bricks and Method of Forming Bricks with High Coal Ash Content"; and, in numerous of our other reports concerning the use of Coal Ash in the making of Cement and Concrete, virtually the entire matter of the products can be made out of Coal Ash and/or other Coal Utilization Byproducts, such as the sludge from desulphurization scrubbers.
In the case of Concrete, that would include the Cement, and, the coarse and the fine aggregate. We'll provide more documentation of those facts in future reports. There are other reasons why "prior art uses do not lead to massive consumption of fly ash"; and, one of those reasons, we think, as with the facts that Coal can be efficiently converted into Gasoline and that Carbon Dioxide can be recycled into Alcohol, but only a few people are doing it, is ignorance. We here are doing our dangdest to combat that; but, shameful truth to tell, we ain't getting' a whole lot of help.)
Summary and Description: The present invention is directed to ceramic materials made from coal fly ash and from municipal solid waste (MSW) fly ash and to processes for producing these ceramic materials. The fly ash is preferably used as it comes from the power plant or the municipal incinerator without any costly cleaning or separation steps. Over 85 weight percent of the ceramic material is fly ash with the remainder being low cost, commercially available additives such as borax and a calcium-containing material such as triple superphosphate (a common inorganic fertilizer), lime, dolomitic lime, or mixtures thereof.
The ash-based ceramic materials are lighter and yet stronger than the corresponding convention products (such as clay based bricks).
(Further, the) environment is helped by reducing the need for ... clay strip mines.
These advantages are achieved by providing a process of
A. mixing the coal fly ash or MSW fly ash with sodium tetraborate and a calcium containing material that is triple superphosphate, lime, dolomitic lime, or mixtures thereof;
B. forming the mixture into a green body;
C. converting the green body into an intermediate body by heating the green body up to a temperature just below the melting point of sodium tetraborate in a manner that allows water and other volatiles to be driven off and further allows carbon to burn off and the resulting gaseous oxidation products to escape;
D. converting the intermediate body into an ash-based ceramic body by firing the intermediate body at a temperature of from just above the melting point of sodium tetraborate to about 1000.degree. C. until the sodium tetraborate and calcium-containing material melt to form a molten flux which reacts with a portion of the fly ash particles to produce a matrix of water-insoluble reaction products which bind the ash particles together; and
E. cooling the ceramic material body to ambient temperature.
The product ash-based ceramic material is made of nonvolatile fly ash residue particles which are bonded together by water-insoluble reaction products formed by the reaction of a molten flux mixture of sodium tetraborate and a calcium-containing material which is triple superphosphate, lime, dolomitic lime, or mixtures thereof with a portion of the residue fly ash particles, wherein the sodium tetraborate comprised from about 4 to about 10 weight percent, the calcium-containing material comprised from more than zero to 5 weight percent, and the residue fly ash particles comprised the remainder of a precursor mixture which produced the ash-base ceramic material.
The present invention provides methods of producing new ceramic materials and structures from ash which includes coal fly ash and municipal solid waste (MSW) fly ash. The coal fly ash is produced by the burning of coal in power and heating plants. The MSW fly ash is produced by the burning of trash, garbage, and even sewage sludge in municipal incinerators. Two important terms are raw fly ash which refers to the ash as it comes from the power plant or the municipal incinerator and residue fly ash which refers to the ash remaining after water and other volatiles have been driven off and carbon has been burned off and the resulting gaseous oxidation products have escaped during the process of this invention. More specific terms are raw coal fly ash and residue coal fly ash and also raw MSW fly ash and residue MSW fly ash.
The coal fly ash includes class C coal fly ash which comes from ... lignite coal and the class F coal fly ash which comes from ... bituminous coal.
The present process works well with high as well as low carbon coal fly ash.
(The above seems contradictory to the earlier statements about Carbon removal; but, the issue might, in fact, have to do with the type of ceramic that is desired. Residual Carbon will "burn out" during the firing in the ceramics kiln, in any case, due to the high temperatures employed. And, the resulting porosity and lighter weight due to the Carbon loss could be a desirable attribute in some ceramic applications, as seems to be confirmed by following statements.)
The coal fly ash preferably contains from zero to 20 weight percent carbon. More preferably the coal fly ash will contain from zero to 15 and still more preferably from zero to 10 weight percent carbon. Low carbon coal fly ash (about 1 to 3 weight percent carbon) is in demand for special applications.
It is useful and economical, therefore, to use coal fly ash containing preferably from 4 to 20, more preferably from 4 to 15, and still more preferably 4 to 10 weight percent carbon. During the process of this invention, carbon is burned out of the coal fly ash. The removal of carbon increases porosity between fly ash particles resulting in a lighter ceramic product.
Sodium tetraborate is the preferred flux material in the coal fly ash or the MSW fly ash ceramic product because it has a relatively low melting point (about 743C) and because it is inexpensive, being present in common, high tonnage minerals such as borax.
The combination of the coal fly ash or the MSW fly ash and only the sodium tetraborate as flux will produce useful ceramic products. This is particularly true of class C coal fly ash which contains substantial amounts of calcium. However, when MSW fly ash or class F coal fly ash is used, care must be taken to avoid overfiring which may result in characteristic cracks in the fly ash ceramic product. One solution to the problem is to reduce the firing temperature at which the molten sodium tetraborate is reacted with portions of the ash particles. This firing temperature is reduced until the cracks no longer appear.
A preferred approach is to add a calcium-containing material that is triple super phosphate, lime, dolomitic lime, or mixtures thereof to the sodium tetraborate flux. The calcium-containing material greatly extends the acceptable firing temperature range and strengthens the coal fly ash or the MSW ash ceramic product. The calcium-containing material is an important part of the preferred embodiment composition and process, especially for class F coal fly ash and MSW fly ash ceramic products. The most preferred calcium containing material is triple superphosphate because it is water soluble and because it produces the strongest ash-based ceramic material products.
Triple superphosphate is produced in large quantities by the fertilizer industry and is inexpensive.
Commercially available lime and dolomitic lime may be used. Limestone (CaCO3) is calcinated (heated) to remove CO2 and produce lime (CaO). Similarly dolomite (about a 1:1 molar ratio of CaCO3 and MgCO3) is calcinated (heated) to remove CO2 and produce dolomitic lime ... .
The general process for producing the coal fly ash or the municipal solid waste (MSW) fly ash ceramic product comprises the following stages:
(1) mixing the raw fly ash with the flux sodium tetraborate and calcium-containing material additives,
(2) forming the mixture into a strong green body of the desired shape,
(3) heating the green body up to the firing a temperature just below the melting point of sodium tetraborate temperature in a manner which allows water and other volatiles to be driven off and further allows carbon to be burned off and the resulting gaseous oxidation products to escape to form an intermediate body,
(4) firing the intermediate body at a temperature of from just above the melting point of sodium tetraborate to about 1000C to form of water-insoluble reaction products which bind the ash particles together and which is formed from the reaction of the flux components (sodium tetraborate and the calcium-containing material) and material from the residue fly ash particles, and:
(5) cooling down the fly ash-based ceramic product.
(And) the ceramic material is excellent for construction."
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There are, though not well-illustrated by our excerpts, at least two, and maybe three, heating and cooling stages, as we understand it; one to form the"green body", and/or an "intermediate body", out of the blended raw materials, and, then, the "firing" to form the final product.
Someone experienced even just from a hobby-centered pottery or ceramics class would understand it all a lot better than we do.
As far as a "ceramic material ... excellent for construction", the Navy scientists are referring to some of the more specific applications they name in the full disclosure, such as blocks, bricks, tiles and pipes.
If there are any old timers among our readers who happened, at one time or another, to be involved in one or another of the construction trades, they will recall that, before plastic got to be such a big thing, there were a lot of various blocks and pipes available, made of stuff, usually clay, that were referred to, or labeled, as "vitrified", such as. for instance:
Vitrified Floor Tiles - Vitrified Floor Tiles Supplier & Vitrified Floor Tiles Manufacturer; and:
National Clay Pipe Institute - NCPI | Vitrified Clay Pipe Gravity Sewer Systems | VCP Technical Resource for Design-Installati; "The National Clay Pipe Institute (NCPI) is a not-for-profit technical resource for design, installation and operation of vitrified clay pipe (VCP) gravity sewer systems".
See also: Vitrified clay pipe - Wikipedia, the free encyclopedia.
Further, so durable and impervious are things which have been "vitrified", that, as in:
ASTM C159 - 06(2011) Standard Specification for Vitrified Clay Filter Blocks; "This specification establishes the criteria for acceptance, prior to installation, of vitrified clay filter block used in trickling filters for the treatment of sewage and industrial wastes";
some of them can be used to treat some pretty nasty industrial effluents, thus helping to clean the environment; and, the EPA loves them, as in:
http://www.epa.gov/superfund/community/pdfs/suppmaterials/treatmenttech/vitrification.pdf; "Vitrification is a process that permanently traps harmful chemicals in a solid block of glass-like material".
Thus, any "harmful chemicals" that anyone is prone to claiming that Coal Ash contains, would, according to the US EPA, be "permanently" trapped in the "Ash-based Ceramic Materials", which, according to the United States Navy, in their Disclosure of our subject "United States Patent 5,521,132", say that we can make out of both Class C and Class F Coal Ash, in such a way that fully "85 weight percent of the ceramic material is fly ash".
We have to, in closing, acknowledge herein the needed assistance of some technical advisors who used to be enthusiastic helpers. Now, they only deign to give us a little of their time when they're not engaged in something more important or critical; like trimming their toenails, we suppose.
Their attitude over the, literally, years, soured when it finally became apparent that the Coal Country press, half a dozen representatives of which these missives are primarily directed to, by the way, has little, if any, apparent interest in the Coal industry, or in Coal people.
Technologies like the one disclosed herein, and those in other of our reports demonstrating that both Carbon Dioxide and Coal have a wide array of profitable, even critical, uses to which they can be put, would seem to us to be of critical economic importance to Coal Country.
If anyone is actually reading these missives; if anyone has actually been motivated to read this far; we must presume that you, too, feel the same way, that you sense the same importance.
If so, it's time you got off your dead cans and told your Coal Country journalists to get off their dead cans.
Otherwise, we will all be swept up in economic and environmental "reforms" that aren't going to reform anything for you but the way you have to shop for groceries and clothes, i.e., at the food bank and the Goodwill Store.
And, if things don't soon change, you might as well start shopping there now, so that you can get good at it and pass the skills on to your children. They are, unless something does soon change in what you're being instructed by your press, going to need them.
