We've been documenting, that, in addition to Carbon Dioxide and it's vast potential as a raw material for the synthesis of hydrocarbons, as seen, for just one out of now many examples, in our report of:
USDOE Converts CO2 to Gasoline | Research & Development; concerning the US Government-owned: "United States Patent 4,197,421 - Synthetic Carbonaceous Fuels and Feedstocks; 1980; Assignee: The United States of America; Abstract: This invention relates to the use of a three compartment electrolytic cell in the production of synthetic carbonaceous fuels and chemical feedstocks such as gasoline, methane and methanol by electrolyzing an aqueous sodium carbonate/bicarbonate solution, obtained from scrubbing atmospheric carbon dioxide with an aqueous sodium hydroxide solution, whereby the hydrogen generated at the cathode and the carbon dioxide liberated in the center compartment are combined thermocatalytically into methanol and gasoline blends";
all of the by-products arising from our indispensable use of Coal in the generation of electrical power are valuable raw materials, useful substances whose true potentials have been ignored, and, perhaps deliberately, even hidden from those of us who most deserve to know of them:
The United States citizens of United States Coal Country.
Even the Ash left behind after the precious Carbon content of Coal has been, one way or another, for one purpose or another, extracted, has potentially-immense utility.
As seen in our reports of:
US Government Coal Ash Cement Stronger than Portland Cement | Research & Development; concerning: "United States Patent 4,256,504 - Fly Ash-based Cement; 1981; Assignee: The United States of America; Abstract: A cement composition comprising a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the cement. Claims: A cement composition consisting essentially of a major proportion of a fly ash ... and (2) about 5 to 15 percent by weight of calcium sulfate"; and:
Exxon Converts Coal Conversion Residues to Cement | Research & Development; concerning: "United States Patent 4,260,421 - Cement Production from Coal Conversion Residues; 1981; Assignee: Exxon Research and Engineering Company; Abstract: Cement is produced by feeding residue solids containing carbonaceous material and ash constituents obtained from converting a carbonaceous feed material into liquids and/or gases into a cement-making zone and burning the carbon in the residue solids to supply at least a portion of the energy required to convert the solids into cement";
the inorganic minerals in Coal represent a valuable by-product residue, a residue that becomes available for utilization after the Carbon content in the Coal has, again one way or another, been extracted or consumed.
And, herein, from one of the very hearts of United States Coal Country, we present further documentation of the fact that Coal Ash is, indeed, a valuable raw material from which we can make a high-performance substitute for Portland Cement, a substitute that not only performs at least as well as Portland Cement, but, which consumes what might otherwise be thought of, and treated, as waste materials in its manufacture.
Comment follows, and is inserted within, excerpts from the initial link in this dispatch to:
"United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste
Date: June, 1998
Inventor: Manyam Babu, et. al., PA
(We suspect the lead inventor's name will tend to stick with you. We will be citing Babu, and some of his colleagues, again in the future.)
Assignee: Dravo Lime Company, Pittsburgh
(A few notes concerning Dravo seem in order here. They were once a major and somewhat diversified engineering, manufacturing and natural resources extraction company, with interests in iron and steel fabrication.
However, as seen in:
DRAVO CORP - 10-K - 19960328 - BUSINESS; "Dravo Corporation was incorporated in Pennsylvania in 1936 to consolidate several related corporations then operating various elements of a business started in 1891 by F. R. Dravo. In December, 1987, Dravo's Board of Directors approved a major restructuring program which concentrated Dravo's future direction exclusively on opportunities involving its natural resources business. The plan included the sale or other disposition of the former Engineering and Construction segment, as well as the sale of the former Materials Handling and Systems segment approved earlier. All units scheduled for sale were sold by the end of 1989. Late in 1994, the company sold substantially all the assets and certain liabilities of Dravo Basic Materials Company, its construction aggregates subsidiary, to Martin Marietta Materials, Inc. (Martin Marietta). As a result, Dravo is now primarily a lime company operating principally in the United States. Operations are carried on by a wholly-owned subsidiary, Dravo Lime Company (Dravo Lime). Activities include the production of lime for utility, metallurgical, pulp and paper, municipal, construction and miscellaneous chemical and industrial applications. (One of their facilities) near Maysville, Kentucky, produces a material marketed under the trade name Thiosorbic(r) Lime, that has a product chemistry ideally suited for removing sulfur dioxide from power plant stack gases. All of Maysville's output is committed under long-term contracts with utility companies in the Ohio Valley region.
Dravo's research and development expenditures were $3.6 million in 1995 and $4.4 million in 1994. Research and development spending in 1996 is expected to exceed $3.1 million. The company expects the research, much of which is being conducted jointly with utility customers, to lower both the capital and operating costs associated with flue gas desulfurization (FGD).
Dravo's position as the world's leading producer of lime for flue gas desulfurization applications was enhanced by the passage of the 1990 Clean Air Act Amendments";
Pittsburgh's Dravo Corporation divested themselves of nearly all of their manufacturing businesses, became the Dravo Lime Company, and now focus on just a few things, one of them being the treatment of Coal-fired power plant exhaust.)
Abstract: Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock.
(As they make clear further on, the source of the "aluminum, iron, silica and carbon" is Coal Fly Ash, which is to be mixed with the "flue gas desulfurization process waste product".)
Claims: A process for producing cement from a flue gas desulfurization process waste product, comprising:
- providing a moist flue gas desulfurization process waste product containing 80-95 percent by weight of solids of calcium sulfite hemihydrate and 5-20 percent by weight of solids of calcium sulfate hemihydrate;
- adding a source of aluminum, iron, carbon, and a siliceous material to said flue gas desulfurization process waste product to form a moist mixture thereof;
- agglomerating said moist mixture while removing water therefrom, by contact with hot air, to provide a dry agglomerated kiln feedstock containing about 6 percent or less water;
(Do you suppose, that, in the vicinity of a Coal-fired power plant, where we would hope to obtain some "flue gas desulfurization process waste product", that we might find a little excess "hot air" to use in this process, for "removing water" from, i.e., drying, the raw material from the FGD scrubber?)
- calcining said dry agglomerated kiln feedstock in a rotary kiln to produce a cement clinker; and
- pulverizing said cement clinker to produce cement.
(Both the "calcining" and "pulverizing" are what they have to do, now, in any case, to produce "cement" from the traditional raw materials. There shouldn't be much, if any, extra expense in any of that just because we're using FGD scrubber sludge and Fly Ash. The raw materials should, in fact, lead to a less-expensive, more environmentally-friendly, energy-conserving overall process, since we won't have to quarry as much of the limestone.)
The process for producing cement from a flue gas desulfurization process waste product ... wherein said source of aluminum and iron comprises fly ash.
(Thus, this is a technology not only for using the FGD scrubber waste, but, what would likely be much larger relative volumes of the Coal Fly Ash, as well. A fact slipped in almost as an aside.)
The process for producing cement from a flue gas desulfurization process waste product ... wherein said waste product results from a flue gas desulfurization process using a magnesium-enhanced lime slurry for reaction with sulfur dioxide in a gas stream.
The process for producing cement from a flue gas desulfurization process waste product ... wherein said waste product results from a flue gas desulfurization process using limestone for reaction with sulfur dioxide in a gas stream.
(Regarding the claims immediately above, Dravo are simply defining the type of limestone to be utilized in the FGD scrubber. Limestone is most often thought of as consisting, basically, of Calcium Carbonate, CaCO3, which can be calcined to produce lime, CaO, with, as we've previously, and tediously, pointed out, the co-generation of CO2. However, in nature, limestone almost always consists in part, as well, of Magnesium Carbonate, MgCO3. Limestone with an appreciably high content of MgCO3, relative to CaCO3, is referred to as "dolomitic" limestone; and, there is plenty of it. Portland Cement made directly, the old fashioned way, by calcining limestone, reflects that composition and always contains some Magnesium, which is, or once was, believed to help enhance the properties of the Cement. There is plenty, absolutely plenty, of cheap dolomitic limestone readily available for use as "magnesium-enhanced lime" in this Dravo process of scrubbing Sulfur from flue gas, and then utilizing the FGD wastes.)
The process for producing cement from a flue gas desulfurization process waste product ... wherein said moist mixture contains between about 5 to 20 weight percent of water.
The process for producing cement from a flue gas desulfurization process waste product ... wherein said dry agglomerated kiln feedstock has a solid content comprising, by weight, 82.77 percent flue gas desulfurization process waste product, 5.80 percent fly ash, 6.43 percent sand, and 5.0 percent coke.
(Unfortunately, Dravo's Cement-making process utilizes far less of the Coal Fly Ash than other, related processes we have documented, and will further document, for you. There are, though, additional uses for Coal Ash related to this process, which we will point out further on.)
The process for producing cement from a flue gas desulfurization process waste product ... wherein sulfur dioxide is produced from calcining of said agglomerated kiln feedstock in said rotary kiln and said sulfur dioxide is discharged from said rotary kiln to an indirect heat exchanger to heat air and air heated in said heat exchanger is used to remove water from said moist mixture during agglomeration.
(Thus, heat is recycled within the process, with resulting economies.)
The process for producing cement from a flue gas desulfurization process waste product ... wherein said sulfur dioxide, after heating air in said heat exchanger is passed to a sulfuric acid producing plant and used for production of sulfuric acid.
(We've previously documented the potentials for producing Sulfuric Acid as a byproduct from some processes for the clean utilization of higher-sulfur Coal. It is a product of broad industrial utility with a ready market, as can be learned via:
Sulfuric Acid; wherein we're told, that: "Sulfuric acid is ... the largest-volume industrial chemical produced in the world (and) consumption of sulfuric acid is often used to monitor a country's degree of industrialization. Agricultural fertilizers represent the largest single application for sulfuric acid (65%). Other uses include production of dyes, alcohols, plastics, rubber, ether, glue, film, explosives, drugs, paints, food containers, wood preservatives, soaps and detergents, pharmaceutical products, petroleum products, pulp and paper."
Thus, any co-production of Sulfuric Acid could present the opportunity for an additional income stream that would help to subsidize the costs of producing Cement from Coal combustion wastes, or, at least, eliminate what might otherwise be mandated costs for disposal.)
A process for producing cement from a flue gas desulfurization process waste product, comprising: providing a moist flue gas desulfurization process waste product containing 80-95 percent by weight of solids of calcium sulfite hemihydrate and 5-20 percent by weight of solids of calcium sulfate hemihydrate; adding a source of aluminum, iron, carbon, and a siliceous material to said flue gas desulfurization process waste product to form a moist mixture thereof; agglomerating said moist mixture while removing water therefrom, by contact with hot air, to provide a dry agglomerated kiln feedstock containing about 6 percent or less water;
calcining said dry agglomerated kiln feedstock in a rotary kiln to produce a cement clinker and sulfur dioxide;
(and) removing said cement clinker from the rotary kiln and pulverizing the same to produce cement;
The process for producing cement from a flue gas desulfurization process waste product ... wherein said source of siliceous material, aluminum and iron comprises fly ash.
Summary: A process for producing cement from a flue gas desulfurization waste product is carried out by providing a moist flue gas desulfurization waste product containing 80-95 percent by weight solids of calcium sulfite hemihydrate and 5-20 percent by weight solids of calcium sulfate hemihydrate and adding thereto a source of aluminum and iron, such as fly ash, carbon, such as coke, and a siliceous material, such as sand, to form a moist mixture. The moist mixture is agglomerated, such as by pelletizing, while removing water therefrom to provide a dry agglomerated feedstock. The dry agglomerated feedstock is charged to a rotary kiln and calcined to produce a cement clinker which is cooled and pulverized to produce a cement. Sulfur dioxide that is released by calcination of the feedstock may be used to produce sulfuric acid."
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Again, unlike other, related, technologies we have made report of, this particular Cement-making process uses far more of Coal exhaust Flue Gas Desulfurization scrubber effluent than it does Fly Ash.
But, that's okay.
As seen in:
Consol Converts Coal Ash to Concrete Aggregate | Research & Development; concerning: "United States Patent 5,364,572 - Process for Making High-Strength Synthetic Aggregates; 1994; Assignee: Consolidation Coal Company, Pittsburgh; Abstract: A process for making high-strength ... aggregates ... from ... coal combustion ash";
and, in:
US EPA Headquarters Housed in Coal Ash | Research & Development; wherein we learn, that: "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 ... the Ronald Reagan Government Office building, home to the Environmental Protection Agency (EPA) in Washington, D.C.";
and, in:
Coal Ash Can Reduce Construction Costs | Research & Development; concerning: "United States Patent 5,624,491 - Compressive Strength of Concrete and Mortar Containing Fly Ash; 1997; Assignee: New Jersey Institute of Technology; Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete";
once the Cement is actually made from FGD wastes and a relatively little Fly Ash, even more Coal Fly Ash, in various forms, can be added to it, as an aggregate, as a replacement for at least some of the sand and gravel normally used, to make structural Concrete, a structural Concrete that is actually stronger than conventional Portland Cement-based Concrete made only with conventional sand and gravel aggregates.
One reason for that is seen in our above-cited earlier report concerning:
"United States Patent 4,256,504 - Fly Ash-based Cement; 1981; Assignee: The United States of America (as represented by the Secretary of the Interior); Abstract: A cement composition comprising a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the cement. Claims: A cement composition consisting essentially of (1) a major proportion of a fly ash ... and (2) about 5 to 15 percent by weight of calcium sulfate. Fly ash, the residue collected in the flues of coal-burning power plants, has been used as a component of concrete admixtures to replace a portion e.g., about 10 to 25 percent, of the conventionally-employed Portland cement";
wherein it's explained that the Fly Ash itself, even when added just as an aggregate after the cement is made, can actually react chemically with the concrete mix as an additional cemetitious material, thus serving as an aggregate with chemical binding properties of its own, unlike inert sand and gravel; and, which properties enhance the strength of the cured Fly Ash cement-concrete composite.
Thus, as in our above comments concerning the fact that we could save some expense by not having to quarry as much limestone to make our cement, we could save additional expense by not having to dredge sand and gravel, for aggregate to make concrete out of that cement.