Energy Citations Database (ECD) - - Document #565273
We've made a number of reports on the what might be the surprisingly large potentials for utilizing our Coal Ash, aka, "Coal Combustion Byproducts" or, just "CCBs", what we here insist is a raw material resource of unrecognized value, as a mineral "filler" in various types of molded plastic.
As we've explained, various minerals, most usually in the form of fine particles, or fibers of various sizes and types, are commonly blended into a plastic resin before the resin is molded, one way or another, into it's final form.
That practice can offer a number of benefits. Not only does it most often reduce the cost of whatever article might be produced, it can also, depending on the choice of filler, enhance or improve some specific physical properties of that article.
And, concerning plastic, and plastic resins, it's important to keep in mind that there are, to generalize, two types that we have to deal with: "Thermoset" and "Thermoplastic".
"Thermoset" plastics, a representative example being the foam used in the seat cushions of your car, another being the resin you might patch rust holes in your car with, are those which take their final form and consistency through a set of chemical reactions. To make something out of a thermoset plastic, you typically have to mix two, more or less liquid, sometimes very "thick" liquid, ingredients together, pour the blend into a mold or form it into a shape, and wait for the chemical reaction between those ingredients to cause the mixed resin to harden.
Further, taking the example of the resin you patch holes in your car with, since most old Coal miners have at one time or another had to patch a few rust holes in their work vehicles, the cured plastic which forms the patch, containing as it most often does both mineral filler and reinforcing glass fibers, is what is known as a plastic "composite"; that is, a blend of plastic with some other things that has better, or just more desirable, physical properties than would any of the individual ingredients alone.
Articles made of thermoset plastic pose some difficulties when it comes to recycling, since they're kind of like cement or concrete, in a way: you can't simply remold them into something else.
"Thermoplastics", on the other hand, are those which are made chemically to be solid to begin with, but, when heated to one degree or another, will melt into a liquid which can be molded into a shape, which, when cooled, solidifies and keeps that molded shape.
In theory, thermoplastics can be re-melted and re-molded any number of times, although additives such as pigments and, as with thermoset plastics, various mineral fillers and even sometimes glass fibers, do, at least eventually, interfere with the practicality of that.
But, thermoplastics are at the heart of the plastics recycling movement, and are the plastics out of which some of the most common consumer items, like beverage containers, are made.
And, as we've previously documented, for one instance in:
West Virginia Coal Association | Coal Ash Reinforced Recycled Plastic | Research & Development; concerning: "US Patent 6,583,217 - Composite Material Composed of Fly Ash and Waste PET; 2003;
Assignees: Iowa State University and The University of Missouri; Abstract: A composite material and method are described wherein melted waste, chemically unmodified PET material and fly ash particles are mixed in a vessel to disperse fly ash particles in the melted PET material. The resulting mixture then is cooled to solidify the melted PET material to form a composite material ... . The method ... wherein said solid, waste, post-consumer PET material comprises beverage bottles ... (and) wherein said fly ash particles comprise Class C fly ash (and/or) Class F fly ash". The present invention is related to composite materials and methods for their manufacture using recycled, post-consumer waste polyethylene terephthalate and fly ash";
the value of adding Coal Ash to some types of recyclable plastic, as a way to combine two kinds of "waste" into something more useful, has, in some places, been recognized and acknowledged.
Herein, we present a more comprehensive take on those potentials; one that provides more of an overview of where and how Coal Ash could be profitably employed in a way that makes useful products while at the same time enabling, or improving, the recycling potentials for scrapped and waste thermoplastic.
And, there is, we think, some import here, as the Coal Country public struggles with issues being reported in the press, such as:
Coal ash provision removed from transportation bill - Business, Government Legal News from throughout WV;
with most Coal Country commentators blindly decrying the fact that a noble attempt by West Virginia's Congressman David Mckinley, to insert some reason into the nation's management of the Coal Ash issue, was seemingly foiled by the US Senate.
What most of those commentators fail to tell us all, though, is, as seen in:
Keystone pipeline not in U.S. transport bill deal: aide - chicagotribune.com; which relates, that: "June 27, 2012; A massive transportation funding bill that the U.S. Congress is trying to pass by week's end will not include a Republican proposal forcing quick approval of the Canada-to-U.S. Keystone oil pipeline, a senior Democratic aide said on Wednesday";
that, some issues near and dear to the heart of Big Oil were dropped from that bill, as well, as were others just as extraneous to "transportation", such as further extending low student loan rates.
Our thoughts are this:
The arguments, and reasons, for forcing the US EPA to drop it's campaign of attempting to over-regulate Coal Ash are compelling, even overwhelming. Coal Ash is a valuable raw material resource, as we've documented many times previously and as we will eventually get around to documenting herein.
What is really needed isn't a rider attached to anything that, in the end, would only slow the EPA down. That would be something that still treats Coal Ash, and, by extension, Coal, and, by even further extension, Coal people, as secondary, an afterthought that just isn't, really, all that important.
What, in our humble opinion, is needed, is a clear, independent and stand-alone statement, in one form or another, that Coal Ash is, indeed, a valuable raw material resource, and, that is the way we are all going to start treating it and dealing with it.
But: We are not going to get such a clear and unequivocal statement like that from our public leaders unless the public itself starts saying as much, as well. And, the public ain't going to start saying it unless they know it; and, they won't know it unless and until the organs of public information let 'em know it's true.
Coal Country Press: Again, get off your dead cans.
Quit whining about the fact that a noble attempt to sneak some common sense about Coal Ash in on the ass end of a totally unrelated piece of legislation was scrapped. The value of Coal Ash is genuine and real, and acknowledgement of that deserves to be presented, and to stand publicly, on it's own. If you Coal Country news people don't have the will or the skill to proclaim and explain that in the pages of your papers, then you have absolutely no standing to criticize or comment on the doings of others in that regard.
You have done nothing to educate or inform, perhaps even to educate and inform yourselves; and, in honesty, you just don't seem any different to us here than a green-hat miner standing on the bench in the shower house, trying his hand at raising the rank and file into some kind of emotional ardor about some perceived affront - - all while his seasoned reps are behind closed doors with management, trying to hammer out some mutually-acceptable and productive solution to whatever problem there might be.
Until it's demonstrated that you actually care enough about Coal and the issues surrounding Coal to educate yourselves about the details, and to expend the effort to write fully and clearly about those details, you have zero cred.
That, with our apologies, said, Coal Ash is, indeed, a valuable raw material resource; as seen, with comment inserted and appended, in excerpts from the initial and following links in this dispatch to:
6 Mb View Document or Access Individual Pages; DOI: 10.2172/565273
"Use of Coal Ash in Recycled Plastics and Composite Materials
Date: July, 1995 (published: November 1995)
Authors: D.J. Hassett, et.al.
OSTI ID Number: 565273; Report: DOE/MC/30097--5676; Contract: FC21-93MC30097
Research Organization: North Dakota University; Energy and Environmental Research Center
For: U.S. Department of Energy; Office of Fossil Energy; Morgantown Energy Technology Center, Morgantown, West Virginia
Sponsor: USDOE Assistant Secretary for Fossil Energy, Washington, DC
Abstract: The goal of this research project by the Energy & Environmental Research Center (EERC) was to determine the potential for coal ash to serve as a functional filler in plastics and other composite materials, with special emphasis on recycled plastics. The term functional filler is intended to indicate that the material added to the plastic does more than take up space and extend the use of the polymer. Determining the functional filler potential of ash was not the only intent of this project, since another prime objective was to find a use for materials currently considered waste. The term functional filler also opened a door to the use of cenospheres, which are currently marketed and for which there is sufficient market demand that they do not fit the category of a waste even though they are a product of coal combustion. Cenospheres, hollow spherical ash particles, were selected because of their unique properties. Although they currently have commercial applications, the unique nature of these materials make them an excellent candidate for use as a functional filler in composites. The ability to produce a commercially viable product from waste streams and a recycled material is a positive step toward reducing solid waste. The first task, since there are numerous types of coal ash, was to select suitable ash types for use in this project. Three basic types of material were selected: fly ash, a bottom ash, and a unique form of coal ash known as cenospheres.
(We interrupt here, since they mention them, to again note the high-value ingredient of Coal Ash known as "Cenospheres"; the nature and utility of which we've documented in a number or previous reports, including, for one example:
West Virginia Coal Association | Wisconsin Recovers "Cenospheres" from Coal Fly Ash | Research & Development; concerning: "United States Patent 8,074,804 - Separation of Cenospheres from Fly Ash; 2011; Assignee: Wisconsin Electric Power Company".)
The initial intent was to use recycled plastic as the binding material. Various attempts were made at melting and forming composites using polyethylene and polyvinyl chloride because these two waste materials could be melted under laboratory conditions. It soon became apparent that without the proper equipment for melting, mixing, molding, extruding, and forming this was not a suitable approach. The approach was shifted to the use of commercially, available polymeric materials that could be used as a starting point in our formulations. Although the materials were not exactly like what would be used commercially, they allowed the demonstration and testing of various combinations. The exploration of all possible recycle plastic streams was beyond the scope of this project. Two polymeric materials exhibiting different properties were selected for the demonstration: I) polyester, which is polymerized through a free radical mechanism using 2-butanone peroxide and acrylic, which is polymerized through a cross-linking of an already partially polymerized product.
(Sadly, what they're explaining in the above is that they didn't have the equipment needed to re-melt and then to re-mold genuine waste thermoplastic after the ash had been added; so, they sort of wimped out and used available, virgin thermoset plastic resin as a "stand-in". The technical results should still be useful, if, again sadly, not directly applicable.)
These are representative of many recycle streams and components and allowed the formation of composite materials for examining basic properties and studying how ash and plastic interacted as composites. since the formulation of the selected materials are proprietary, the exact composition of individual components was not known. In practice, the variety of acrylic and polyester in recycle streams would be relatively large. The likely source of polyester would be from plastic carbonated beverage containers. Polyester is used in this application because of its ability to retain carbonation. Most common polymers are permeable to gases, especially carbon dioxide under pressure. Polyesters can be prepared with high strength-tensile strength as high as 25,000 psi can be achieved. Additionally, polyesters are relatively scratch-resistant. Acrylic polymer recycle material would likely come from industrial sources where acrylics are used in the fabrication of various products.
The term acrylic encompasses a large variety of polymers dominated by poly(methy1 methacrylate), better known as plexiglas. Additionally, poly(methy1 methacrylate) composite dental fillings are prepared from a polymer-monomer dough with a ceramic filler (not unlike coal ash), thus demonstrating‘the high strength that can be achieved with this material. The polymer produced in this manner is what is described as atactic, which means that there is no regular structure in the polymer ... .
Key areas such as polymer-ash interactions, adhesion, and basic composite properties were investigated.
Results and Discussion: During the course of the project, more than 36 tiles were produced. A rubber molding compound was cast around a tile, and this mold was, in turn, used to form tiles made from
composites of resin and ash. Numerous formulations were tried at various solid-to-liquid ratios. The
formulations used to produce the trial tiles were made at optimum solid-to-liquid ratios that would allow material handling, yet incorporate the greatest amount of ash for each resin and ash combination. At least two tiles of each possible combination were produced. Trial tiles for strength and morphology were produced from combinations of fly ash, slag, ... and cenospheres with acrylic and polyester.
The primary differences in the various tiles were in appearance, bulk density, and strength (as illustrated in accompanying tables and graphs).
The addition of coal-combustion by-products (CCB) to plastic provides an additional option for formulation of new composite materials. This is the incorporation of properties of ash in polymeric materials. Ash is known to be both pozzolanic and cementitious. Cementitious reactions can occur in these two forms in ash.
Pozzolanic CCBs give rise to strength formation in mixes with lime, and water and CCBs that are cementitious materials provide strength with the addition of water only. This leads to some interesting speculation with composite materials. Although beyond the scope of this project, there is a possibility that the cementitious and pozzolanic properties of CCBs could exist at the fractured or cut surface of a polymer CCB composite by exposing fresh CCB surfaces. This would give rise to a plastic composite that would give adhesion with cement-based grouts and adhere to setting cement surfaces. Additionally, the addition of cenospheres could give rise to enhanced bonding properties of a cut composite surface by providing concave surfaces as well as undercut surfaces that would provide bonding sites in polymers not normally amenable to bonding with common adhesives.
Polyester with fly ash ... appeared to be somewhat scratch-resistant. With slag addition, a material was formed that had a rough surface, which should provide excellent adhesion and antiskid properties on potentially slippery surfaces and areas. Although the apparent scuff resistance of the cenosphere and ash composites, especially with acrylic resin, was such that floor application would be unlikely, the slag composites had properties that might make floor application a suitable option. The application of polyester ash blends in flooring applications might be a topic for further investigation.
There are undoubtedly numerous applications for light, strong, nonconductive, water-resistant, and aesthetically attractive plastic composites. These materials appear to be a product waiting for a market. In advanced construction applications where being lightweight and having high strength are important factors, these materials might provide a suitable answer.
During the course of this research project, tiles were prepared using polyester and acrylic resins. Three ash types were used: slag, fly ash, and three grades of cenospheres.
It can be said in conclusion that:
There is a high potential for the use of recycle plastic in the formulation of composite materials using CCBs as functional fillers.
The use of CCBs in composites can result in materials considerably different from the parent materials and exhibiting properties of each of the starting materials.
Strong and lightweight composites can be formed from plastic and cenospheres. Cenospheres, lightweight hollow ash particles in composites, can result in materials with high strength and a bulk density less than 1.0, making them lighter than water.
A composite material incorporating fly ash can be prepared that is aesthetically pleasing, strong, and potentially wear-resistant.
A composite can be prepared from slag and plastic that has skid resistance. The antislip properties of this composite might make an excellent safety product for applications where slippery conditions are likely.
The adhesion of cement-based grout has high potential and should be evaluated.
Up to nearly 80% replacement of plastic by weight can be achieved using fly ash or slag.
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We have attempted to distill the essence of the thing in our excerpts. The bulk of the document is mostly graphic in nature and we didn't want to independently attempt to over-summarize, or to extrapolate too much from the data provided.
There is also discussion and summarization of the replacement of plastic by Ash on a volume basis; and, that is also significant.
We will say that, as we perceive from our reviews of the literature, Cenospheres are something of a "glamour" item among the CCB people nowadays; and, perhaps too much attention got diverted herein into examination of them, detracting from effort that might have been better applied to the bulk of the Ash.
The data presentations, and brief explanatory discussions, were not, we do confess, entirely positive. Some composite properties improved with the addition of Coal Ash; while some did not. Some even deteriorated to a certain extent, relative to the amount of Ash used. But, that is true as well of the standard and accepted commercial mineral fillers now used in plastic composites, and the trade-offs are known and utilized. For instance, to return to the case of polyester resin used for patching rust holes in automobiles, the resin is highly-filled with mineral powder so that the rates of thermal expansion and contraction of the cured patch will be closer to that of the metal, so that the patch doesn't peel away as the seasons, and temperatures, change. The trade-off is that the patch doesn't "stick" to the metal quite as well as the pure resin would, and, it isn't quite as resistant to impact as it could otherwise be.
The sum is, though, that a "composite material incorporating fly ash can be prepared that is aesthetically pleasing, strong, and potentially wear-resistant" and, that we can, for some applications, on a practical basis, replace "nearly 80% ... of plastic by weight (with Coal) fly ash".
Although the size of that potential market isn't nearly as large as the one for using Coal Ash in the manufacture of Cement and Concrete, it is still significant and could well be profitable, especially since the Coal Ash would be replacing other minerals that would otherwise require, at some considerable economic and environmental expense, mining and milling.
And, the economic benefits would be in addition to the environmental benefits, since the effort described herein was, in the first place, intended to be one which demonstrated the "Use of Coal Ash in Recycled Plastics", a use that would, by combining two streams of otherwise valueless "waste", result in the production of commercially viable composites that are both "aesthetically pleasing" and "strong".
Coal Ash can be made to be "aesthetically pleasing". Who woulda thunk it?
