We've many times reported on the fact that Coal-fired power plant fly ash can serve as a beneficial and property-enhancing replacement for most, or even all, of the mined, quarried or dredged sand and gravel ordinarily blended into Portland-type Cement (PC), to make Portland-type Cement Concrete (PCC).
As seen, for one example, in our report of:
Coal Ash Concrete More Durable, Resists Chemical Attack | Research & Development | News; concerning the USDOE-sponsored:
"United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar; 1998; Assignee: New Jersey Institute of Technology, Newark; 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 acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance. Government Interests: The research leading to the present invention was conducted with Government support under Contract No. DE-FG22-90PC90299 awarded by the Department of Energy. The Government has certain rights in this invention";
such use of Coal Ash in PCC, as demonstrated by contractors working for the US Department of Energy, can result in concrete that is in some ways much more durable than conventional PCC.
The fact that our United States Government at least quietly recognizes such value of Coal Ash is further confirmed in our report of.
US EPA Headquarters Housed in Coal Ash | Research & Development | News; wherein, among other things, we're taught, by the CertainTeed Corporation, that:
"The U..S. Environmental Protection Agency (EPA) recognizes fly ash as an industrial by-product of the coal combustion process in electricity-generating power plants. The EPA supports the beneficial reuse of fly ash in construction applications because it is safe and reduces the amount of coal combustion residue sent to landfill. In addition to its beneficial reuse in our fiber cement products, fly ash has been used in concrete since the 1930’s. Most notably, it has been used in several construction projects and prominent buildings, including the Ronald Reagan Government Office building, home to the Environmental Protection Agency".
Further, as we've documented via other references in separate reports, and as can be learned from the United States Geologic Survey, USGS, via:
http://minerals.er.usgs.gov/minerals/pubs/commodity/sand_&_gravel_construction/mcs-2013-sandc.pdf; "SAND AND GRAVEL (CONSTRUCTION): Domestic Production and Use";
the United States typically produces, via dredging, quarrying, etc., more than 800 million tons of sand and gravel per year; and, a little more than 40 percent - -, that is, by extrapolation, something more than 320 millions tons - - of that is destined for use "as concrete aggregates".
And, as can be learned from the American Coal Ash Association, who is, by the way, now charged with, by the USGS, the keeping of Coal Ash production and use statistics, via:
http://www.acaa-usa.org/Publications/ProductionUseReports.aspx;
the United States produced around 52 million tons of Fly Ash in 2012. However, we must note that there are some inconsistencies, sometimes large inconsistencies, in numbers. For instance, one group reports volumes in "short tons", while another uses "metric tons". And, it is in some data compilations, even in those provided by the ACAA, difficult to parse out, of the total Coal Combustion Products reported, what portion is Fly Ash, as opposed, for example, to Bottom Ash and Flue Gas Desulfurization sludge, etc.
Other sources, and even different interpretations of ACAA data, state, or could lead to the conclusion, that more than 70 million tons of Fly Ash is generated.
An expert from the American Coal Ash Association could parse it all out for you; and, we, here, are most definitely not experts.
Clearly, though, as we have previously reported, much more than all of the Coal Fly Ash produced by the United States of America each year could be productively used and consumed, as reactive aggregate in the manufacture of higher-performing Portland-type Cement Concrete. And, if such use for Coal Ash were actively supported and expanded, and the demand for Coal Ash consequently grew, we would be put in the situation where current production couldn't meet demand; and, we would be motivated to begin mining older accumulations of Coal Ash, where it had been land-filled or otherwise disposed of, preparing that Ash, and then providing it to the Concrete manufacturing industry.
And, that is the thrust of the technology we report to you herein: a variation on current Coal Ash beneficiation techniques, one intended to reclaim Coal Ash that has already been disposed of and land-filled, and to prepare it for market, for use as a reactive aggregate in Portland-type Cement Concrete.
Comment follows and is inserted within excerpts from the initial link in this dispatch to:
"US Patent 7,670,424 - Methods for Reclaiming and Beneficiating Fly Ash Particles and Systems Thereof . . .
Date: March 2, 2010
Inventor: Joseph Cochran, FL
Assignee: PMI Ash Technologies, NC
(http://www.pmiash.com/ "PMI Ash Technologies; Providing Superior Solutions For Your Fly Ash Challenges")
- - - (Note: As can be learned via:
PMI Ash Technologies, LLC: Private Company Information - Businessweek;"PMI Ash Technologies, LLC provides economic ash management solutions. The company through carbon burn-out process eliminates fly ash disposal and produces pozzolan for use in concrete. It also produces Aardelite, a lightweight aggregate from non saleable fly ash. PMI Ash Technologies, LLC was formerly known as Progress Materials Inc. The company was founded in 1986 and is based in Cary, North Carolina. It has a facility in Crystal River, Florida";
"PMI Ash Technologies" is the former "Progress Materials Inc.". We had previously made a number of reports on the Coal Ash beneficiation technologies developed by PMI/Progress Materials. However, those were posted so many years and hundreds, even thousands, of R&D reports ago, that we can no longer track them down in the West Virginia Coal Association's online Research and Development archives. One about which we're certain we did report, and, with special applicability to the Coal Ash reclamation technology being disclosed herein is:
"United States Patent: 5160539 - Method and Product of Fly Ash Beneficiation by Carbon Burnout in a Dry Bubbling Fluid Bed
Date: November, 1992
Inventor: Joseph Cochran, FL
Assignee: Progress Materials, Inc., FL
Abstract: This invention relates to an apparatus, method and product wherein fine particles of fly ash containing carbon are oxidized in a dry, bubbling fluid bed of previously introduced fine particles of the same fly ash so that the subsequently removed particles have reduced carbon content and are useful as pozzolan, suitable for use, without further processing, to replace a portion of the cement in concrete. The preferred conditions are a temperature of about 1300 to 180 F., air velocity of between at least about 0.5, but not more than about 3 ft./sec., residence time of at least about 2 minutes but up to 100 minutes, volume ratio of air to fly ash of between about 1,000 and 1500, and an excess of oxygen between about 5% and 15%.
Claims: The method of reducing carbon content of fine particles of fly ash containing carbon, comprising: a) introducing said fly ash fine particles containing carbon to a dry bubbling fluid bed consisting essentially of said particles, and: b)oxidizing said carbon in the fly ash particles by intimately mixing said particles with air in said bed at a temperature of between about 1300 and about 1800 F., by introducing ambient air to said bed at a volume ratio of between about 1000 to about 1500, air to fly ash, at a velocity of between at least about 0.5, but less than about 3.0 ft./sec., and said particles having a residence time in said bed of at least about 2 minutes, but up to about 100 minutes, c)then removing said fly ash particles from said bed, wherein said particles have had the carbon content reduced by said oxidation, so that said removed fly ash particles are enhanced pozzolan suitable for use, without further processing, to replace a portion of the cement in concrete".
The above technology is being adapted herein, in the process of our subject, "US Patent 7,670,424 - Methods for Reclaiming and Beneficiating Fly Ash Particles and Systems Thereof", for application to Fly Ash that has been recovered from disposal sites.) - - -
Abstract: A method and system for reclaiming and beneficiating fly ash particles includes recovering at least a portion of fly ash particles from reclaimed feed and supplying at least a portion of the recovered fly ash particles to at least one mixing reactor with a chamber where at least a portion of the supplied fly ash particles are thermally beneficiated.
Claims: A method for reclaiming and beneficiating fly ash particles, the method comprising: recovering at least a portion of landfill fly ash particles from reclaimed feed previously disposed in at least one landfill site, the reclaimed feed comprising the fly ash particles and at least one non-by product of coal burning resulting from the disposal at the at least one landfill site; supplying at least a portion of the recovered fly ash particles to at least one mixing reactor with a chamber; and thermally beneficiating at least a portion of the supplied fly ash particles in the chamber.
The method ... wherein the recovering further comprises: mixing the reclaimed feed to at least partially separate the fly ash particles; and heating the reclaimed feed with other fly ash particles and at least one gas obtained from the chamber to dry the fly ash particles prior to the thermally beneficiating (and) wherein the recovering further comprises: mixing the reclaimed feed to at least partially separate the fly ash particles; and heating the reclaimed feed with an exhaust gas from the beneficiating at least a portion of the supply fly ash particles in the chamber to dry the fly ash particles prior to the thermally beneficiating.
The method ... wherein the recovering further comprises digging out the reclaimed feed from the landfill site, wherein the reclaimed feed includes content dug from the landfill site.
The method ... wherein the supplying further comprises supplying at least one gas to direct the at least the portion of the recovered fly ash particles to the chamber (and) wherein the beneficiating further comprises providing at least one fluid to the chamber for the beneficiating (and) wherein the beneficiating further comprises heating the at least one fluid at least during a startup period (and) further comprising providing fly ash particles from at least one other source for the beneficiating.
(As we take the above, the reclaimed Ash can be blended with Ash hot off the griddle, so to speak, that is, fresh, at a facility nearby a Coal-fired power plant, which would reduce some of the need for externally-supplied thermal energy. In fact, Carbon Burn-Out techniques, if enough fresh ash is used, since it's residual carbon content is higher due to mandated pollution controls that inhibit complete combustion, can be thermally self-sustaining. Otherwise, additional heat can be supplied via heat exchange with the power plant exhaust. It might sound complicated and involved, but, if you examine PMI's web site, you will discover, that, as in our report of:
Virginia Converts Coal Ash to Cash | Research & Development | News; concerning, in part: ""Dominion Recycling Center Turns Ash to Cash"; The Virginia Pilot; November, 2006; CHESAPEAKE (VA) - It looks like a really big igloo, or maybe an indoor skating rink. But Dominion Virginia Power says the new, domed structure next to its Chesapeake power station will make money, create jobs and help the environment.The waterfront facility, on the Elizabeth River just south of the Gilmerton Bridge, is an ash recycling center - the first of its kind in Virginia, and just the fourth in the nation. The facility acts like a big oven. It bakes black, carbon-laden fly ash into a kinder, gentler and paler byproduct that can be sold and made into concrete, roof tiling and construction blocks, among other alternative uses";
the technology is being installed and commercially utilized.)
The method ... wherein an operating temperature of a fluid bed of the at least the portion of the recovered fly ash particles is at or below about 1375 F (and) wherein the at least one non-by product of coal burning comprises water and the fly ash particles are wet and the recovering further comprises removing the water from the fly ash particles.
Background and Field: This invention generally relates to methods and systems for processing fly ash particles and, more particularly, to methods for reclaiming and beneficiating fly ash particles and systems thereof.
During the process of burning coal in utility or large industrial furnaces, fly ash particles are produced. These fly ash particles constitute about 10% of the total weight of the coal burned and fly ash historically was considered a waste product which was collected and shipped to designated land fill sites for disposal. Depending upon the particular type of coal which was burned, the fly ash particles could contain mineral content which made disposal difficult and expensive.
As disclosed in U.S. Pat. Nos. 5,160,539 and 5,399,194, which are each herein incorporated by reference in their entirety, techniques to utilize these fly ash particles for a beneficial purpose have been developed. More specifically, these patents disclose systems and methods for using combustion processes to thermally beneficiate fly ash particles by reducing the carbon content. The fly ash particles beneficiated by these inventions can be used as a substitute for a portion of Portland cement.
(See our above inserted link to, and comment concerning, the above-cited U.S. Patent 5,160,539.)
Unfortunately, prior to the development of the above-identified techniques, substantial amounts of fly ash particles had already been disposed of in designated landfill sites. Additionally, despite these breakthroughs substantial amounts of fly ash particles from coal burning plants that do not utilize this technology continue to be disposed of in designated landfill sites. Unfortunately, the high moisture content of landfill fly ash gives it physical properties that make it unusable as a feed material for the above-identified techniques as well as for other competing fly ash beneficiation techniques. To date, no commercially viable techniques to reclaim and beneficiate the fly ash particles which have been disposed of in these landfills have been developed.
Summary: A method for reclaiming and beneficiating fly ash particles in accordance with embodiments of the present invention includes recovering at least a portion of fly ash particles from reclaimed feed where reclaimed feed refers to material reclaimed from one or more fly ash landfills which becomes feed material for the present invention. At least a portion of the recovered fly ash particles is supplied to at least one mixing reactor with a chamber and at least a portion of the supplied fly ash particles in the chamber are beneficiated.
A system for reclaiming and beneficiating fly ash particles in accordance with other embodiments of the present invention includes a reclaim system, a supply system, and a beneficiation system. The reclaim system recovers at least a portion of fly ash particles from reclaimed feed and the supply system provides at least a portion of the recovered fly ash particles to at least one mixing reactor with a chamber. The beneficiation system comprises the at least one mixing reactor with the chamber that beneficiates at least a portion of the supplied fly ash particles.
A method for making a system that reclaims and beneficiates fly ash particles in accordance with other embodiments of the present invention includes providing a reclaim system that recovers at least a portion of fly ash particles from reclaimed feed. A supply system is connected to the reclaim system and to at least one mixing reactor with a chamber to provide at least a portion of the recovered fly ash particles. A beneficiation system comprising the at least one mixing reactor with the chamber is provided that beneficiates at least a portion of the supplied fly ash particles.
Accordingly, as described herein the present invention provides an effective method and system for reclaiming and beneficiating fly ash particles from reclaimed feed from one or more disposal sites. With the present invention, previously unusable fly ash particles at a disposal site can now be reclaimed and beneficiated into a commercially viable product. Additionally, with the present invention landfill sites with fly ash particles which contain undesirable content can be effectively and economically removed from the landfill site."
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Keep in mind, as is explained in the full Disclosure, if only touched on in our excerpts, the "undesirable content" in the Ash which needs to be removed, aside from unburned Carbon, is really just Water. And, this invention is simply a way in which soggy old Coal Ash that has long ago been carted off and buried can be mined, combined with fresh Coal Ash nearby a Coal-fired power a plant, and then, in such admixture, be successfully and economically treated by a "Carbon Burn-Out" process, thus producing a valuable pozzolanic, property-improving admixture to, or even replacement for some of, Portland-type Cement in Concrete mixtures.
There are at least a few advantages appending to such a concept.
For one, using Coal Ash reclaimed from a landfill as an aggregate in or additive to PCC would productively and profitably remediate an accumulation of materials that could someday, depending upon how the wind, so to speak, in the legals sense, blows, become a liability, either for the owner of the landfill property or for the originator of the Coal Ash.
Another, more positive advantage is, that, while creating at least a few more Coal Country jobs, such productive reclamation and consumption of Coal Ash would reduce the amount of mining, quarrying and dredging that might otherwise have to be done on relatively virgin lands and in waterways to obtain the sand and gravel that the reclaimed Coal Ash would be replacing in the PCC mixes.
Aside from those perhaps indirect benefits, keep in mind, again, that PCC made with Coal Ash, as explained for another example in our report of:
Coal Ash in Concrete Saves $100 Billion | Research & Development | News; concerning: "'The Economic Impacts of Prohibiting Coal Fly Ash Use in Transportation Infrastructure Construction'; 2011; American Road & Transportation Builders Association Transportation Development Foundation. Executive Summary: Fly Ash: A High-Return “Green” Building Material; Fly ash concrete has a number of very significant, well-documented benefits that make it a mixture of choice for many state and local transportation departments and transportation engineers. It is more durable, yet less expensive than other traditional portland cement blends. Fly ash concrete has also been praised for its environmental benefits as a “green” building material—putting to use an energy production byproduct that reduces the demand for carbon-intensive portland cement and requires less water in the hydration process. ... Concrete is a major transportation construction material in the United States. Twenty-five percent of the Interstate Highway System is paved in concrete. And it has been used to build 65 percent of the nation’s bridges (and, more) than 75 percent of that concrete ... utilizes fly ash as a partial cement replacement blend";
offers so many advantages, in terms of increased strength and enhanced corrosion resistance, relative to conventional PCC, that, if it were universally employed in the building of our United States transportation infrastructure, it could save us many tens of billions of dollars in terms at least of avoided repair costs.
Coal Ash can be seen and treated as a valuable mineral resource; and, the technology of our subject, "United States Patent 7,670,424 - Methods for Reclaiming and Beneficiating Fly Ash Particles and Systems Thereof", would make more of it accessible for profitable use.