United States Patent Application: 0120031306
As pretty much any old country boy who's ever fiddled around at all in the construction trades knows, there's a difference between what we might call cement blocks and what are generically known as "bricks".
Typically, cement blocks are simply molded out of a Portland-type cement blend, with a large percentage of some added small aggregate, often just some sort of cinders from a handy, nearby industrial furnace (thus, "cinder block"), and allowed to cure, or "set", before being shipped and used.
If you're blessed enough to be living in a home without axles, such "concrete", "cement", or "breeze" blocks are likely what your home is resting on in it's foundation walls.
And, in point of fact, likely unbeknownst to many of our readers, Coal Ash has long been used in some places as the "cinder" aggregate for such concrete block; a fact unconsciously commemorated in Great Britain, where, as any old limeys among your circle of friends might confirm, concrete block is often still called "breeze block", the word "breeze" being the quaint label the sometimes inscrutable Brits once applied to Coal Ash.
The technical potential for such use of Coal Ash is explained in our report of:
West Virginia Coal Association | Coal Fly Ash Bricks are Greener and Stronger | Research & Development; concerning: "United States Patent 7,998,268 - Method to Produce Durable Non-vitrified Fly Ash Bricks and Blocks; 2011; Inventor: Henry Liu; Assignee: Ecological Tech Company, Inc.,MO; Abstract: A method of making durable, non-vitrified masonry units comprising fly ash";
with the "non-vitrified" meaning the "masonry units" being described aren't really "bricks" in our common understanding of the word, since, like ordinary concrete block, they are aren't being first molded into shape and then "fired" in a brick kiln and, thus, being "vitrified".
Note that such vitrified "masonry units" are, again as might be intuitively realized, quite a lot denser, stronger and tougher than plain old cement blocks and slabs. You can, for instance, pave roads with bricks; something you somewhat obviously couldn't do with the cement or concrete "pavers" you can buy to make walkways and patios out of down at your local building supply do-it-yourself store.
That doesn't mean, however, that we can't make honest-to-goodness kiln-fired bricks out of Coal Ash.
And, we can do so in pretty much the same way that we make them out of the traditional raw materials.
As seen in excerpts, with comment and additional links inserted and appended, from the initial link in this dispatch to:
"US Patent Application 20120031306 - Bricks and Method of Forming Bricks with High Coal Ash Content
(BRICKS AND METHOD OF FORMING BRICKS WITH HIGH COAL ASH CONTENT USING A PRESS MOLD MACHINE AND VARIABLE FIRING TRAYS - Belden, )
Date: February, 2012
Inventor: Robert Thomas Belden, et. al., Ohio, France(!), Maryland and Florida
(We interrupt here to, first, note again that the ultimate assignees of rights to US patents, if different from the inventor, or inventors, is usually not named in early or initial publications of US patent applications. In this case, the ultimate assignee of rights will almost certainly be the almost down-home, but still surprisingly large, Belden Brick Company, headquartered in Canton, OH. More about them can be learned via their own web site:
BELDEN - THE BELDEN BRICK COMPANY - Your Brick, Paver and Special Shapes Resource - Canton Ohio:
"The Belden Brick Company traces its roots to the Diebold Fire Brick Company organized in Canton, Ohio in 1885 by Henry S. Belden and four associates. The Belden Brick Company owns and operates six plants in Tuscarawas County, employ approximately 500 people and have an annual production capacity of nearly 250 million standard brick equivalent. Plant 3 and one line at Plant 8 produce soft mud (machine-molded) brick while the other facilities all produce extruded brick products. The Belden Brick Company also owns and operates two brick distributorships, The Belden Brick Sales Co. in Fraser, Michigan and Belden Brick Sales & Service, Inc. in New York, New York and Saddle Brook, New Jersey. In the fall of 1996, The Belden Brick Company bought Redland Brick Inc., which consisted of three brick plants, Harmar Brick near Pittsburgh, Cushwa Brick in Williamsport, Maryland, and KF Brick near Hartford, Connecticut. In the spring of 2000, Redland Brick Inc. purchased the Rocky Ridge (MD) plant. Redland Brick Inc. continues to operate its four plants under its own management as a wholly owned subsidiary of Belden Holding & Acquisition, Inc., the parent company of The Belden Brick Company. In the US brick industry, The Belden Brick Company is the sixth largest (by production volume) manufacturer. Belden Brick is the largest family owned and managed brick company in the United States"; and via:
Brick Company | Brick Manufacturers.)
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). Also provided is a variable firing tray to support the dried, high content coal ash bricks/pavers as the dried products are sent through a tunnel kiln, to improve circulation around the individual bricks/pavers and thereby result in reduced firing time in the kiln.
("Class F coal ash", by the way, is what we get by combusting our high-Btu eastern bituminous Coal; although Belden, et. al., do get around to noting that Class C Coal Ash from western Lignite Coal can also be utilized in pretty much the same fashion.)
Claims: A process for the manufacture of bricks by press molding, the process comprising:
a) providing a mixture of at least 60% fly ash and up to 40% of clay, shale, or a mixture thereof;
b) introducing the mixture from (a) to a press mold and molding the mixture into green bricks;
c) drying the green bricks for about 12 to 18 hours to render dried bricks;
d) loading the dried bricks onto variable firing trays and stacking the variable firing trays on kiln cars;
e) firing the dried bricks in a kiln for up to about 55 hours; and:
f) removing the fired bricks from the variable firing trays, wherein the process consumes about 560 BTUs per pound of manufactured brick.
The process ... wherein the fly ash comprises Class C fly ash, Class F fly ash, or a combination thereof.
The process ... wherein the mixture of step (a) further includes less than a few percent barium and/or colorant.
(The remaining claims actually, in large part, go on to describe what other references about brick making would seem to indicate are just more or less standard steps in the brick making process, as is pretty much true about the claims we reproduced above, except the part about the "fly ash". It all seems, based on our admittedly-shallow review, standard brick-making, just with a lot of Coal Ash involved. Somebody, if there is anybody out there, genuinely interested in Coal Ash, could just call the Beldens and ask them if that is, in fact, the case.)
The process ... wherein ... the fly ash fuses to bind EPA regulated hazardous material present in the fly ash within the fired brick to eliminate leaching of the hazardous materials from the fired brick.
(The above is important. All of the, real or fantasized, compounds of concern to the environmentally-sensitive among our brethren will be locked up in vitrified brick far tighter than it would be even if it were, as the old Coal Mine saying about tightly-secured things goes, stuffed up a bull's butt at fly time. Water, simply, does not leach through brick, which is, in fact, a type of ceramic. And, what should be needles to say is that vitrified brick is pretty immune to chemical attack, as well. Whatever is in it to begin with ain't ever coming out.)
A fly ash brick comprising, in the fired state, up to 80% fly ash.
The brick ... wherein the brick has a compressive strength, as defined in ASTM (c1272-07), of 10,000 psi for extruded brick and 8,000 psi for molded brick.
(See:
ASTM C1272 - 11a Standard Specification for Heavy Vehicular Paving Brick; "This specification covers heavy vehicular paving bricks designed for use in streets, commercial driveways, aircraft taxiways, and other places where there is a high volume of heavy vehicular traffic. The bricks should be manufactured from clay, shale, or similar naturally occurring earthy substances and subjected to firing. The high temperature heat treatment should develop sufficient fired bonds between the material particles to produce the required strength and durability. The bricks may also be shaped by extruding, molding, or pressing during manufacture and may have spacing lugs, chamfered edges, or both. The materials are classified into two types according to the intended installation and should all conform to the required values of freeze thaw resistance, abrasion resistance, skid resistance, coring, chips or cracks, and efflorescence."
These Coal Ash bricks, in other words, are heavy-duty, high-performance, value-added items.)
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.
Background and Description: This application is directed to making bricks and more particularly to a process of manufacturing bricks, and the resultant bricks manufactured by the process, having a high coal ash content. For purposes of the present application, coal ash generally includes both fly ash and bottom ash, and thus reference to any of coal ash, fly ash, and bottom ash can be used interchangeably unless specifically noted otherwise. Selected aspects of the present disclosure may find application in related manufacturing processes.
Brick manufacturing is well known and has been developed over thousands of years so that even today the commercial process is substantially unchanged over many years. The most widely used processes are either to mold or press mold the bricks or alternatively to extrude the bricks. Shale (dry clay) or clay has water added in a desired amount along with other constituents to form a green body. The green body is subsequently dried to remove moisture in the brick, then fired to incipiently fuse or vitrify the components, and next cooled in a controlled manner to result in the final brick that has structural strength and integrity as widely used in the construction industry.
As an example only, in order to make press molded brick the clay or shale is first ground and mixed with water to the desired consistency. The clay is then pressed into molds with a press, and the molded clay is then fired or burned at approximately 900-1150C to achieve strength. Alternatively, the bricks subsequently move slowly through a tunnel kiln on conveyors, rails, or kiln cars. The bricks often have added lime, ash, and organic matter to speed the burning process.
In contrast, with extruded brick, ground clay or shale is mixed with 10-25% water and the material is pushed forced through a die to form the desired width and depth. The extrudate is subsequently cut into bricks of the desired length. The cut bricks are then dried for about 20 to 40 hours at approximately 400F to harden before being fired in the kiln. Oftentimes, the heat for drying is residual heat from the kiln.
Like any process, manufacturers are constantly evaluating new materials and processes in an effort to reduce the cost of the final product, and particularly without any loss in performance of the manufactured product. Various attempts to incorporate different low cost materials into the brick have been made. For example, pulverized coal-fired power plants generate large quantities of coal ash which includes what is generally referred to as bottom ash and fly ash. Fly ash is the fine-grained, powdery particulate material that is carried off in effluent gas emitted by the power plant. Electrostatic precipitators, filters, cyclones, or other devices are used by the power industry to collect the fly ash and significantly reduce the amount of fly ash released into the atmosphere.
Disposal of these residual ash materials is estimated to cost on the order of $85 billion in the US and, if placed in a landfill, the bottom/fly or coal ash is treated like a hazardous material.
A need exists to include a greater content of coal ash into bricks. Likewise, incorporating greater coal ash content that improves processing times, cost of manufacture, energy utilization, and maintenance of desired brick quality and strength characteristics, is advantageous from manufacturing, sustainability, and environmental points of view.
A coal ash-based brick product has been developed that looks and functions like conventional clay brick and contains up to 80% coal ash. The accompanying test data relates to a 70% coal ash/30% clay or shale brick mixture. The coal ash is preferably residual ash generated from the burning of bituminous coal, i.e., Class F fly ash. This type of fly ash is a non-hydrating coal ash, and does not self-cement. In contrast, Class C fly ash, which is derived from sub-bituminous coal, is a self-cementing ash that will form a solid product with the addition of water. Of these two ash types, historically there have been fewer recycle options for Class F fly ash. As will be appreciated, use of the Class F fly ash is particularly appealing.
Summary: 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).
The coal ash-based brick offers several other advantages as a brick product. For example, reduced energy consumption in a kiln is a primary advantage realized by the present process. Both cost/energy and greenhouse gas emissions are substantially reduced.
On average, a coal ash brick will consume about 560 BTUs per pound which is below conventional brick making which might consume, for example, approximately 1300 BTUs per pound.
(STRUCTUREmag - Structural Engineering Magazine, Tradeshow: Reducing Embodied Energy in Masonry Construction; The "Brick Industry Association now states its average is 1239 BTU per pound". If you consider that a brick, according to various web-based sources, weighs, on coarse average, five pounds; and, if you think about how many bricks are out there and being made, the potential energy savings enabled by the use of Coal Ash are, thus, unequivocally, rather astonishing.)
The resulting brick has improved aesthetics, namely, deep, long-term natural colors resulting from the chemical makeup of the coal ash. Aesthetics and color-fastness are very desirable characteristics in the brick industry.
A substantial reduction of raw material costs and a decrease in the demand of mined virgin clay or shale materials also results in a substantial reduction in consumption of these materials and resulting improvement associated with the coal ash brick."
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To sum it up, according to a long-established major US brick manufacturer, we can make bricks, bricks that are apparently stronger, more durable and look better than bricks made out of the traditional raw materials, out of "60% to 100% coal ash". Moreover, such Coal Ash bricks are less expensive to make, they don't need nearly as much heat energy to be fired, and they don't generate as much Carbon Dioxide in the overall process of their manufacture as do traditional bricks.
Moreover, the natural environments which might otherwise be inconvenienced in the mining of traditional clay raw materials for brick making can remain undisturbed.
As we noted above in passing, the manufacture of fired brick, as herein, is very much a "ceramics"-type process, although there might not seem to be much in common between a basic red brick and your mom's favorite porcelain vase or the necessary fixtures in your bathroom.
They are, though, all interrelated and connected through their basic technologies of manufacture; and, as we will see in reports to follow, some perhaps surprising entities have been following up on the potentials for utilizing and consuming our astonishingly valuable Coal Ash in the manufacture of fired, ceramic products; products like those made via the process of our subject, "US Patent Application 20120031306 - Bricks and Method of Forming Bricks with High Coal Ash Content"; ceramic products that are less expensive to make in the first place and, in the end, perform better.
