United States Patent Application: 0100056356
We've previously documented for you the work of University of Kentucky scientists in the development of technologies for the beneficiation of Coal Ash; that is, making Coal Ash ready for market, as in our report of:
West Virginia Coal Association | University of Kentucky Prepares Coal Ash for Market | Research & Development; concerning:
"United States Patent 6,533,848 - High Quality Polymer Filler and Super-Pozzolan from Fly Ash; 2003; Inventors: Thomas Robi and John Groppo, Kentucky; Assignee: The University of Kentucky, Lexington; Abstract: A novel method for producing fly ash material with a range of particle sizes (as specified) is provided utilizing superplasticizers. The method produces fly ash material suitable for use as filler material in the plastics industry and super pozzolan for the concrete industry".
In addition to using Coal Ash as a "filler" in certain types of plastic and as a property-enhancing "pozzolan" in Portland-type Cement Concrete, we've also documented, as in, for two examples:
West Virginia Coal Association | Coal Ash & Metal Composites Save Gas, Reduce CO2 | Research & Development; concerning: "Aluminum - Fly Ash Metal Matrix Composites as Advanced Automobile Material;
Final Report; September, 2001; Cosponsors: United States Department of Energy; Wisconsin Electric Power Company; Electric Power Research Institute (EPRI)"; and:
West Virginia Coal Association | Coal Ash and Aluminum Alloy Composites | Research & Development; concerning, in part: "United States Patent 5,711,362 - Method of Producing Metal Matrix Composites Containing Fly Ash; 1998; Inventor: Pradeep K. Rohatgi, Milwaukee, WI; Assignee: Electric Power Research Institute (EPRI), CA; Abstract: A reinforcing phase comprising fly ash is combined with an aqueous medium comprising a binder to produce a slurry. The slurry is then dried to produce a preform of the reinforcing phase. Molten metal is then introduced into the preform, resulting in a metal matrix composites. The reinforcing phase of the subject composites may be present in excess of 50%";
that, Coal Ash can also serve as a cost-reducing, property-enhancing filler for certain types of molded metal, especially Aluminum, in what are called "Metal Matrix Composites".
And, that is the specific thrust of the further technology developed herein by the above-cited University of Kentucky scientist Thomas Robl, and colleagues, as seen in excerpts from the initial link in this dispatch to:
"United States Patent Application 20100056356 - Methodology and Technology for the Production of Improved Coal Derived Fly Ash for the Production of Metal Matrix Composites
Date: March, 2010
Inventors: Thomas Robl, et. al., Kentucky
(Note: As is most often the case, the eventual "Assignee of Rights" to US Patents that might issue from patent applications is not specified in web-accessible United States Patent and Trademark Office patent application publications. Other available documents demonstrate that the University of Kentucky, through one or the other of its research and intellectual property foundations, was the original, intended Assignee of Rights to the invention disclosed herein. As we will see in additional information following the excerpts, that might have changed.)
Abstract: A method for preparing a metal-fly ash composite material includes classifying a fly ash-containing material to provide a classified fly ash material having a mean particle size (as specified). The classified fly ash material is blended with a metal matrix whereby the fly ash material and the metal matrix form a substantially homogenous mixture. Suitable conditions of temperature and/or pressure are applied to form a metal-fly ash composite material is formed. The metal matrix may be provided as a liquid or as a powder.
Claims: A method for preparing a metal-fly ash composite material, comprising: classifying a fly ash-containing material to provide a classified fly ash material having a mean particle size (as specified); blending the classified fly ash material with a metal matrix whereby the fly ash material and the metal matrix form a substantially homogenous mixture; and subjecting the mixture to suitable conditions of temperature and/or pressure whereby a metal-fly ash composite material is formed.
The method ... further including subjecting the classified fly ash material to a secondary thickening process prior to the step of combining with a metal matrix (and) a step of removing magnetic particles from the classified fly ash material prior to the step of blending with a metal matrix.
The method ... wherein the fly ash containing material is derived from coal.
The method ... wherein the classified fly ash material is included in an amount of from about 5 (percent by volume) to about 25 (percent by volume) of the classified fly ash-metal matrix mixture (and) wherein the metal matrix is aluminum or an aluminum alloy.
The method ... wherein the metal matrix is provided as a melt (or) as a powder.
(Specifics are included about the further processing of the respective "melt" or "powder" blends.)
Background and Field: The present invention relates to metal matrix composite materials, and in particular to such composite materials incorporating ash derived ceramic particles from coal combustion ash.
The United States is the largest mining country in the world. In 2001, the mining industry produced $57.3 billion in raw materials, of which $19.0 billion was derived from coal. The mineral processing industries increased the value of the minerals to $374 billion, while coal and uranium were used to produce $147 billion of electricity. Thus, the minerals and coal industries combined to contribute $521 billion to the nation's wealth (approximately 5.2% of the Gross National Product).
(Because) of the potential utility of fine coal products such as fly ash, efforts have been made to incorporate such products into metal matrix composite (MMC) materials, with the goal of producing metal alloy composites of superior hardness, stiffness, and durability. Such composites also typically provide an end product of less weight than the corresponding metal or metal alloy.
Extensive efforts to fabricate ash-aluminum MMCs have met with limited success. In particular, the inconsistent quality of such materials in the past has greatly hampered development, and thus such materials have found limited success in the marketplace. For that reason, present commercial MMCs are typically based on SiC or Al2O3. However, the potential applications for suitable MMCs are extensive and have potentially great value. Using the motor vehicle industry as an example, simple replacement of ductile iron brake rotors with rotors fabricated of an MMC would provide significantly improved performance (due to at least improved thermal conductivity) and weight reduction, concurrently improving fuel efficiency of vehicles using such technology. Similarly, applications currently using hyper eutectic aluminum alloys, such as in manufacture of pistons, engine blocks, and heads, would benefit from incorporation of MMCs. In particular, in addition to the reduced cost of aluminum-ash MMCs compared to currently utilized MMCs, aluminum-ash MMCs can be machined with more conventional tooling, enhancing their desirability in such manufacturing processes.
In attempting to fabricate suitable MMCs such as aluminum-ash MMCs, it is necessary to address the issues of "wetability" and reactivity. In particular, it is not a simple matter to wet fly ash with molten aluminum, despite similarities in overall density of the materials. Thus, early efforts have resulted in end products with undesirable levels of porosity, and indeed with pockets of agglomerated ash in the form of stable flocs which are resistant to mechanical shear, and very difficult to disperse.
In addition, coal fly ash is formed in a highly oxidized environment, whereas molten aluminum is an extremely reducing environment. Thus, exposure of ash to molten aluminum creates oxidation-reduction reactions, forming spinel, reducing SiO2 to Si metal, and other problematic reactions. Hydrogen formation forms voids, increasing porosity and decreasing strength of the final product. Release of alkali metals (i.e., Na and K) can "dewet" the ash.
Still further, fly ash is a heterogenous material, containing cenospheres, magnetite, and carbon, and also tends to include a wide range of particle sizes. This contributes to quality issues for the final MMC product.
Accordingly, there remains a need in this art for methods of producing MMCs which reduce reactivity of the fly ash component, to reduce the tendency to form flocs. There further remains a need in the art for such methods which reduces porosity of the final product and creates an end MMC product of improved hardness, stiffness, and strength.
Summary: In one aspect, the present invention comprises reducing heterogeneity of fly ash intended for use in producing aluminum ash MMC, wherein the fly ash product is treated to remove contaminants such as cenospheres and the like. In one embodiment, the method comprises classifying a fly ash-containing material to provide a classified fly ash material having a mean particle size (as specified), blending the classified fly ash material with a metal matrix whereby the fly ash material and the metal matrix form a substantially homogenous mixture, and subjecting the mixture to suitable conditions of temperature and/or pressure whereby a metal-fly ash composite material is formed. The metal matrix may be in a molten state or a powder form.
The fly ash product may be classified by passage through a suitable classifier. The classifier may be any suitable classifier capable of separating out the finest (<5 .mu.m) particles, minimizing surface area of the fly ash product. In this manner, reactivity of the fly ash is reduced, and also the tendency of the ash to form flocs.
(Robl, et. al., herein make reference to prior or concurrent art, perhaps that embodied, in part, by the above "United States Patent 6,533,848 - High Quality Polymer Filler and Super-Pozzolan from Fly Ash".)
Metal matrix composites are materials consisting of two or more distinct phases and exhibiting desirable properties derived from each phase. The objective of the present studies was to produce a lightweight ash-derived ceramic (ADC)-aluminum metal matrix composite (MMC) with improved stiffness and wear resistance. Such materials have application in a variety of industries, such as in the transportation industry to replace ductile iron in manufacture of, e.g., brake rotors, engine cylinders, and the like.
There are accordingly provided methods for forming metal matrix composites via a variety of techniques, and metal matrix composites formed thereby. (In the experiments and tests as detailed, the) materials exhibited good machinability (and were) capable of achieving strengths and hardness that exceeded the reference (non-reinforced) alloys.
These materials find use in applications that require decreased weight and cost savings without sacrificing performance. For example, aluminum metal matrix composites could be used as engine blocks or brake rotors in automobiles. The presence of the (Coal Ash-derived Ceramic, or ADC) will harden the aluminum making it more compatible with such applications. Additionally, the weight savings over ductile iron will add to the fuel economy and energy efficiency of the vehicle. Ash derived ceramics are recycled from an energy product making them sustainable and environmentally friendly materials."
-------------------------
Coal Ash, in other words, just as when it's used as a component of Cement and Concrete, can be an "environmentally friendly" product. As we've explained before, not only does the Coal Ash make the end-use Metal Matrix Composite more durable, thus reducing the need for and costs of replacement, but, by the amount Coal Ash replaces metals such as Aluminum, it also reduces the financial and environmental costs of mining and refining those metals.
And, the development, by Thomas Robl and others at the University of Kentucky, of such Coal Ash beneficiation technologies has led to the formation of a company to utilize those processes, and to market the products those processes derive from Coal Ash, as can be learned via:
NuForm Materials -Ash Derived Ceramics; wherein were told, variously, that:
"NuForm Materials, LLC uses a patented beneficiation process to obtain high purity, value-added ceramic materials for automotive and aerospace composite material applications that require superior performance, improved fuel efficiency, and low cost. Our customers use our recycled ash derived ceramics to produce improved and lightweight metal matrix and polymer composites that, in turn, enhance the performance of their customers’ products in the field. As an added benefit, our products are recycled directly from an energy byproduct making them environmentally friendly, sustainable, and inexpensive"; and:"Dr. Thomas Robl is President and Co-Founder of NuForm Materials. His background includes the development of ash beneficiation technology and product applications for all forms of coal utilization products, including pulverized coal fly ash, bottom ash, scrubber sludge, and fluidized bed combustion ash and gasification slag. He has over 30 years research experience in fossil energy utilization, has been P.I. on over $15 million in external research funding, and has written numerous technical articles and reports as well as several patents".
---------------------
As noted, Dr. Robl, of the University of Kentucky, the lead named inventor of our subject herein, "United States Patent Application 20100056356 - Methodology and Technology for the Production of Improved Coal Derived Fly Ash for the Production of Metal Matrix Composites", has co-founded a company intended it seems to utilize those technologies; and, to bring those Coal Ash beneficiation technologies, and the products of those technologies, to market.
We have not, so far, been able to determine what, if any, relationship exists between the University of Kentucky and NuForm Materials, LLC. There might be none, except for Thomas Robl.
In sum, Coal Ash can be, and is being, treated as a valuable mineral resource.
In addition to its use in the manufacture of high-performance Cement and Concrete, and as a "filler" for certain types of plastic, Coal Ash can be beneficiated and prepared for consumption and utilization in the manufacture of Mixed Metal Composite materials, MMC's, with the end products made from those MMC's not only being less expensive in terms of energy and raw materials to manufacture, but, as well, performing better than standard metal materials in certain high-volume, end-use applications.