We've previously documented for you that Coal Ash can serve as a natural resource-sparing raw material in the manufacture of various types of ceramics, a class of materials which would include such things as bathroom tiles and, even, fired bricks.
Our reports on that topic have included:
West Virginia Coal Association | 1936 Ceramics "New Market" for Coal Ash | Research & Development; concerning: "United States Patent 2,055,706 - Method of Making Ceramic Products; 1936; Assignee: Chicago District Electric Generating Corporation; Description: This invention relates to an improved method of making fired ceramic bodies by the addition thereto in the unfired state of fly ash resulting from the combustion of pulverized fuel, and the improved product resulting from the use of such method"; and:
West Virginia Coal Association | US Navy Makes Ceramics from Coal Ash | Research & Development; concerning: "United States Patent 5,521,132 - Ash-based Ceramic Materials; 1996; Assignee: The USA as Represented by the Secretary of the Navy; Abstract: A ceramic material made from raw coal fly ash".
Herein, through a collection of one related report and a couple of patent documents, we further confirm such generally unacknowledged potentials for putting the unjustly-vilified solid residua arising from our essential use of Coal in the generation of truly abundant and genuinely economical electrical power to good, profitable work.
As seen in excerpts from the initial link in this dispatch, with additional links and excerpts following:
"United States Patent 5,935,885 - Manufacture of Ceramic Tiles from Fly Ash
Manufacture of ceramic tiles from fly ash - Vortec Corporation
Date: August 10, 1999
Inventor: James Hnat, et. al., PA and FL
Assignee: Vortec Corporation, PA
(Insofar as we have been able to determine, "Vortec" no longer exists as an independent company. They were, apparently, a relatively small operation. That's okay, since, as we will see, they had some rather large, and durable, friends and partners, including the United States Department of Energy.)
Abstract: The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants.(The "metal contaminants" would, of course, be forever, and inextricably, safely and securely, locked up in the ceramic tiles. Seriously, if anyone would ever raise any objection to the use of Coal Ash in such an application, it would only be necessary to begin educating the public about what compounds now, currently, go into the formulation of ceramic glazes. How do people think we get those pretty colors?)
Government Interests: This invention was made with Government support under Contract No. DE-FG02-93ER81555 awarded by the Department of Energy. The Government has certain rights in this invention.
Claims: A process of forming glass ceramic tiles comprising: providing a spent ash containing organic material, metallic contaminants, and glass forming materials; oxidizing the spent ash under conditions effective to oxidize the organic material and to partially oxidize the metallic contaminants and the glass forming materials, wherein said oxidizing is carried out in a suspension preheater in which the ash containing the organic material, metallic contaminants, and glass forming materials is suspended in an oxidizing fluid;
vitrifying the oxidized glass forming materials to form a glass melt; forming the glass melt into glass ceramic tiles containing metallic contaminants.
(Note that the above "wherein said oxidizing is carried out in a suspension preheater in which the ash containing the organic material, metallic contaminants, and glass forming materials is suspended in an oxidizing fluid" sounds a lot like the "Carbon Burn-Out" pretreatment for Fly Ash which is intended to be used as an admixture in Portland Cement Concrete, as we've reported once or twice, as, for instance, in:
West Virginia Coal Association | South Carolina Prepares Coal Ash for use in Concrete | Research & Development; concerning: "United States Patent 8,234,986 - Method and Apparatus for Turbulent Combustion of Fly Ash; 2012; Assignee: The Sefa Group, Inc., SC; Abstract: An apparatus for processing fly ash comprising a heated refractory-lined vessel having a series of spaced angled rows of swirl-inducing nozzles which cause cyclonic and/or turbulent air flow of the fly ash when introduced in the vessel, thus increasing the residence time of airborne particles. Also disclosed is a method of fly ash beneficiation using the apparatus. Claims: A method for reducing the carbon content of small particulate combustion products said small particulate combustion products consisting essentially of fly ash or fly ash with chemical residue and/or contaminants, said small particulate combustion products being a product of a previous combustion and containing unburned carbon and incombustible matter".
There is, in fact, a fairly large body of technical literature "out there" concerning such Coal Ash beneficiation processes; and, we'll try to do a better job of reporting and explaining them to you in the future. The value of Coal Ash in the manufacture of Concrete and, as herein, Ceramics, makes them worth doing.)
A process ... wherein said suspension preheater is a counter-rotating vortex suspension preheater.
(The above claim is really making reference to a type of air suspension "Carbon Burn Out" process. The "counter-rotating vortex suspension" seems almost synonymous with the more simply put "swirl-inducing" of "United States Patent 8,234,986 - Method and Apparatus for Turbulent Combustion of Fly Ash".)
A process ... wherein said vitrifying is carried out in a cyclone melting chamber (or) in an open-hearth melter (or) in an electric melter (and) wherein said oxidizing is carried out at a temperature of 1000 to 1500 C (and)
wherein said vitrifying is carried out at temperature of 1200 to 1550 C.
A process ... further comprising: mixing the fly ash with an additive selected from the group consisting of limestone, dolomite, gypsum, silica, sodium-lime-silica glass cullet, titania, zirconia, and mixtures thereof (and) other oxides ... selected from the group consisting of oxides of copper, manganese, chromium, nickel, zinc, arsenic, lead, gold, silver, sulfur, and mixtures thereof ... .
(Some, if not all, of the above, nasty as one or two of them might sound, are standard admixes for ceramics as they are conventionally made. And, we are condensing the full Claims section to a large extent. The addition of those fairly standard ceramic admixtures is accomplished in ways a bit more complicated than our abbreviated excerpts make it all seem.)
A process ... further comprising: cooling the tiles to effect nucleation and heating the tiles after said cooling to cause crystallization of said tiles (and) glazing the heat treated tiles.
A process of forming glass ceramic tiles comprising: providing an ash containing organic material, metallic contaminants, and glass-forming materials; oxidizing the ash under conditions effective to oxidize the organic material and to partially oxidize the metallic contaminants and the glass forming materials, wherein said oxidizing is carried out in a suspension preheater in which the ash containing the organic material, the metallic contaminants, and glass-forming materials is entrained in an oxidizing fluid; vitrifying the oxidized glass-forming materials to form a glass melt, wherein said vitrifying is carried out in a cyclone melting chamber; forming the glass melt into tiles containing the metallic contaminants; cooling the tiles to effect nucleation; heating the tiles after said cooling to cause crystallization of said tiles, whereby the tiles become a glass ceramic; and glazing the heat treated tiles ... (and) heat treating the glazed tiles, whereby the tiles become a glass ceramic.
(All of the above sounds like a lot of bother, we know; but, our, admittedly cursory, background review of ceramics manufacturing indicates that they're not specifying anything too out of the ordinary just because Coal Ash is the raw material. The above is pretty much how they go about making conventional ceramic tiles, so the Coal Ash isn't adding a whole lot of expense to the process.)
Summary: The present invention relates to a process for forming glass-ceramic objects, such as tiles. Fly ash (that contains) organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants."
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And, in which ceramic "tiles" any "metallic contaminants" that might be present in the Coal Ash utilized in their manufacture will be forever locked up, and permanently prevented from entering the environment.
The above process and concept is not only confirmed by an additional, though precedent, patent issued to Vortec, and what seems to have become their much more substantial business partner, but, it is expanded a bit. The use of Coal Ash in such ceramics applications seems to enable, or is at least compatible with, the productive consumption and safe use of other, but genuinely hazardous, wastes. As seen in:
"United States Patent: 5830251 - Manufacture of Ceramic Tiles from Industrial Waste
Manufacture of ceramic tiles from industrial waste - Vortec Corporation
Date: November, 1998
Inventors: James Simpson, ... James Hnat, et. al., PA and Italy
Assignees: Vortec Corporation, PA, and Welko Industrial S.P.A., Milano, Italy
(Here's where it gets a bit more interesting. "Vortec" no longer seems to exist; but, they might ultimately, have been assimilated by "Welko", a large, multinational Italian firm specializing in the manufacture ceramic products for the individual consumer, construction and industrial markets; more about which can be learned via:
Welko S.r.L. - ceramics processing machinery; "Welko group plays worldwide an important role in the design and production of complete lines and turn-key plants for ceramic industry (tiles, china-ware and sanitary-ware). Welko is present since years 50s in the area of both ceramics processing machinery and turn-key plants. Jointly with its subsidiary companies in Europe and abroad, Welko designs and manufactures technological components and machinery that are installed in the most updated production lines for ceramics".
The appearance of Welko herein adds considerable "heft" to these technologies for the use of Coal Ash. They manufacture ceramics, and ceramic- and tile-making machinery, literally around the world; and, will appear in a few additional reports to follow concerning the use of Coal Ash in the making of ceramics.)
Abstract: The present invention relates to a process of forming ceramic tiles having the appearance of tiles produced from clays. The process includes melting a material to form a glass melt, treating the glass melt to produce a solid glass product, grinding the solid glass product to produce glass particles having a particle size of less than 200 microns, mixing the glass particles with a first additive to form a glass powder mixture having a composition of 55 to 99 wt. % glass particles and 45-1 wt. % first additive, forming the glass powder mixture into tiles by dry pressing, where the tiles have a primary crystalline phase selected from the group consisting of nepheline, diopside, anorthite, wollastonite, melilite, merwinite, spinel, akermanite, gehlenite, crystalline phases based on iron substitutions in the crystalline phase, and mixtures thereof. The process includes a devitrifying step where the solid glass product is devitrified prior to the grinding step or the glass particles in the tile are devitrified after the forming step.
Claims: A process of forming ceramic tiles having the appearance of tiles produced from clays comprising: melting a material which includes waste materials to form a glass melt; treating the glass melt to produce a solid glass product; grinding the solid glass product to produce glass particles having a particle size of less than 200 microns; mixing the glass particles with a first additive comprising a binder selected from the group consisting of clay, organic material, inorganic material and mixtures thereof, to form a glass powder mixture having a composition of 55-99 wt. % glass particles and 45-1 wt. % first additive; forming the glass powder mixture into tiles by dry pressing; and devitrifying the glass particles in the tile after said forming step under conditions effective to form tiles having a primary crystalline phase (as specified) mixing the material used to form the glass melt with a second additive selected from the group consisting of sand, flyash ... and mixtures thereof prior to said melting step to form a mixture.
Summary: A variety of industrial wastes are suitable for producing a recyled glass composition which comprises the majority of the material in a traditional dry pressing tile process. Using these industrial wastes, ceramic tile bodies can be obtained with up to 98 weight percent recycled glass in the tile body. Types of industrial waste useful as a feed material for the present invention include, for example, coal fired utility boiler flyash, municipal waste incinerator ash, spent pot liners from aluminum reduction, metal plating waste, electric arc furnace dust, foundry sands, sewage sludge ashes, and cement kiln dusts."
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The full disclosure of "US Patent 5,830,251 - Manufacture of Ceramic Tiles from Industrial Waste" is much more detailed and lengthy, and concerns itself more with the use of recycled glass in the making of ceramic tiles, and the specifics of the process. The mention of "coal fired utility boiler flyash" is more of an "oh, we can toss some of this in, too" kind of deal, but the point is the same:
Coal Ash can be productively utilized and consumed in the manufacture of ceramics.
That fact is again confirmed in a technical paper presented by Vortec, as accessible via:
"'Proceedings of the 17th Biennial Waste Processing Conference; ASME 1996; Recycling Of Boiler And Incinerator Ash Into Value Added Glass Products; James G. Hnat, Ph.D.,and Leonard M. Bartone, P.E.,Vortec Corporation, Collegeville, Pennsylvania; Abstract: The disposal of industrial solid wastes presents a major challenge to industrialized nations. Boiler ash and incinerator ash represents a major portion of the solid wastes which must be ultimately reused or landfilled. This paper discusses the recycling of coal-fired boiler and incinerator ashes into value added glass products via the use of a newly developed, fossil fuel fired, high temperature melting process. The patented technology is based on advanced in-flight suspension glass melting technology which has been developed by Vortec Corporation with funding support from the U.S. Department of Energy and the Environmental Protection Agency. The Vortec patented Cyclone Melting System (CMSTM) has a number of significant advantages for recycling solid wastes including: the oxidation of organic and metal contaminants, formation of non-leachable glasses which can be sold as value added products, high melting efficiencies, multi-fuel capability, low operating and maintenance costs and low NOx emissions. This paper summarizes some of the challenges facing process industries and utilities in the recycling and reuse of industrial solid wastes. The results of laboratory and pilot scale testing with several pulverized coal-fired boiler ashes, several municipal solid waste incinerator ashes, and a sewage sludge incinerator ash are summarized. Information on ash properties, melting characteristics, system performance, toxicity characteristics leaching procedure (TCLP) testing results, flue gas emissions, recycled products, and economics are presented. The application of the CMSTM to the production of several value added glass and ceramic products is also discussed."
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We'll eventually have more to offer, from other sources, concerning the use of Coal Ash in the making of ceramics, including some indication of volume potentials. It is an application that has drawn additional interest in a few places overseas.
In sum, though, as again confirmed herein, the solid residua resulting from our essential use of Coal in the generation of abundant and truly economical, affordable electric power constitute a valuable raw material resource.
Coal Ash can prevent disruption of the environment by replacing some of the natural raw materials - - natural raw materials that would otherwise have to be mined, quarried or dredged - - in the making of various ceramic products.