We've documented many times, as in our report of:
West Virginia Coal Association | USDOE Says Coal Ash Could End Aluminum Ore Imports | Research & Development; concerning, in part: "Resource Recovery from Coal Residues; 73rd Annual Meeting of the American Institute of Chemical Engineers; 1980; G. Jones, et. al.; Oak Ridge National Laboratory; USDOE; Abstract: Several processes are being developed to recover metals from coal combustion and conversion residues. Methods to obtain substantial amounts of aluminum, iron, and titanium from these wastes are presented. The primary purpose of our investigation is to find a process that is economically sound or one that at least will partially defray the costs of waste processing. A cursory look at the content of fly ash enables one to see the merits of recovery of these huge quantities of valuable resources. The major constituents of fly ash of most interest are aluminum (14.8%), iron (7.5%), and titanium (1.0%). If these major elements could be recovered from the fly ash produced in the United States (60 million tons/year), bauxite would not have to be imported, iron ore production could be increased, and titanium production could be doubled";
that, Coal Ash can serve as a valuable ore from which economically and strategically critical metals, the raw ores of most which we now must import, can be extracted and refined.
However, we've also documented many times, as in our report of:
West Virginia Coal Association | Pittsburgh Converts Coal Ash and Flue Gas into Cement | Research & Development; "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste; 1998; Assignee: Dravo Lime Company, Pittsburgh; 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 (and) wherein said source of aluminum and iron comprises fly ash";
that, Coal Ash in all it's types and forms, perhaps better referred to as Coal Combustion Residuals, CCR's,
can be wholly consumed in the manufacture of a higher-performing, natural resource-sparing Portland-type Cement.
Further, as we've seen in:
West Virginia Coal Association | Standard Oil Converts Coal Conversion Residues into Cement | Research & Development; "United States Patent 4,174,974 - Process for Converting Coal Ash Slag into Portland Cement; 1979; Assignee: Standard Oil Company of Indiana; Abstract: Disclosed is a manufacturing process for converting coal ash slag from a slagging coal gasifier into a marketable cement product having the characteristics and qualities of portland cement"; and:
West Virginia Coal Association | WVU & Canada Cement from Coal Liquefaction Residues | Research & Development; "United States Patent Application 20120090510 - Forming Cement as a By-Product of Coal Liquefaction; 2012; Inventor: Alfred H. Stiller, Morgantown, WV; Assignee: Quantex Research Corporation, Calgary, Canada";
the inorganic mineral residua resulting from the conversion of Coal into hydrocarbons, through both the indirect gasification and the direct liquefaction of Coal, can, as well, be consumed and fully utilized in the making of such Portland-type Cement.
And, herein, we present even more confirmation of that inherent value of the solid mineral residua of Coal use, especially with regards to the indirect conversion of Coal into hydrocarbons via an initial process of gasification; a confirmation with an additional improvement that provides, as well, for a reduction in Sulfur emissions from a Coal gasification process, an improvement that can actually enhance the efficiency of the production of hydrocarbons via such an indirect syngas production process.
As seen in excerpts from the initial link in this dispatch to:
"United States Patent 4,396,432 - Process for Converting Coal to Gaseous Fuel with Production of Portland Cement as a By-product
Date: August 2, 1983
Inventor: William Rostoker, IL
Assignee: University of Illinois Foundation, Chicago
Abstract: Continuous process for converting coal to gaseous fuel with production of Portland cement as a by-product comprises the step of pelletizing a mixture of finely divided coal and limestone, heating (coking) the pellets in a reducing gas atmosphere to liberate volatile fuel products, and converting a substantial proportion of the residual carbon in the pellets to CO and hydrogen by the water-gas reaction, the inorganic constituents of the coal being simultaneously converted to Portland cement clinkers.
(We note that most US Patent documents include a separate summary of prior art US Patents. Among the two cited herein as prior art by the University of Illinois is that seen in our report of:
West Virginia Coal Association | 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";
with, thus, further confirmation that the mineral residua resulting from both the direct and the indirect conversion of Coal into hydrocarbons can be consumed in the making of Portland-type cement.)
Claims: A continuous process for converting coal to Portland cement and liquid and gaseous fuels comprising the steps of
(a) mixing finely divided coal with sufficient finely divided limestone to provide in the mixture an appropriate ratio of Portland cement-forming constituents, measured as CaO, SiO2 and Al23,
(b) forming the mixture from step (a) into discrete pellets,
(c) heating said pellets in a reducing atmosphere at an elevated temperature sufficient to release the volatile constituents of said coal as a fuel product stream,
(d) converting a major proportion of the carbon content of the residual pellets from step (c) to carbon monoxide and hydrogen by reaction with steam at an elevated temperature,
(What is being referred to in step "(d)", of course, is basically a Coal gasification process, much like that disclosed, for only one example, in our report of:
West Virginia Coal Association | Standard Oil 1953 Syngas from Coal, CO2 and Cellulose | Research & Development; concerning: "United States Patent 2,644,745 - Production of Gases from Carbonaceous Solids; 1953; Assignee: Standard Oil Development Company; Abstract: The present invention relates to the conversion of carbonaceous solids into combustible gases. More specifically, the invention is concerned with the gasification of all types of coal ... to produce ... gas mixtures containing CO and H2 suitable for the catalytic synthesis of hydrocarbon and oxygenated compounds".)
(e) reacting the residual solid product from step (d) with a limited proportion of oxygen to convert the remaining carbon content thereof to CO, the heat evolved being sufficient to achieve Portland cement-forming temperatures, and maintaining said temperature for a time sufficient to form Portland cement clinkers;
(f) recovering the gases produced in steps (d) and (e); and
(g) grinding said clinkers to produce Portland cement powder.
The process ... wherein the gases produced in steps (d) and (e) are fed to step (c) as said reducing atmosphere.
The process ... wherein said coal and said limestone have a particle size less than about 150 microns.
The process ... wherein said said pellets are formed with Portland cement as a binder.
Description and Background: The present invention relates to an improved method for conversion of coal into gaseous and liquid fuels, and more particularly to such a process in which the ash content of the coal is converted to Portland cement, while the sulfur content thereof is fixed in a form which reduces atmospheric pollution.
(It seems gratuitous to note the additional benefit, described above, as in our introductory citation of "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste", of sequestering any Sulfur contained in the Coal in the resulting Coal Ash cement product.)
Background and Description: With the increasing cost and decreasing availability of petroleum and natural gas, greater emphasis is being placed on the use of coal as a source of energy. Several processes have been developed whereby coal can be converted to a variety of liquid and gaseous products useful as fuel or as feedstocks for chemical conversion to other desired products. In any such process, however, a serious problem which must be overcome is the disposition of large amounts of ash, representing the inorganic constituents of the coal, which has little or no economic value. In addition, and particularly in the case of coal containing relatively large amounts of sulfur, the sulfur-containing gases, such as SO2, SO3, and H2S which are formed in the process present serious problems with respect to corrosion of equipment or pollution of the atmosphere. While these problems can be solved by the use of special corrosion-resistant equipment and by treatment of effluent gases to remove sulfur compounds, these expedients increase the cost of any process for utilizing coal in this manner and render the economics unfavorable in comparison to the use of petroleum-based products or natural gas.
The problems of ash disposal, atmospheric pollution and corrosion of equipment in known processes for converting coal to liquid and gaseous products are solved in accordance with the invention by mixing the coal with an appropriate concentration of limestone, which reacts with the inorganic constituents of the coal during the process to produce Portland cement, which can be used or sold as a valuable by-product.
In the process, the sulfur content of the coal combines with a portion of the added limestone to form solid products which appear ultimately in the Portland cement product in concentrations sufficiently small to have no adverse effect on the quality of the cement. By suitable temperature control and by maintaining reducing conditions throughout the process, the appearance of sulfur in any gas phase is suppressed, thereby eliminating the necessity for scrubbing any of the gaseous product streams to remove sulfur.
Briefly described, the process of the invention involves the steps of preparing an intimate mixture of finely divided coal and finely divided limestone, pelletizing the mixture with the aid of an appropriate binder, and heating (coking) the pellets in a reducing gas atmosphere to liberate normally gaseous (H2, CO, CH4) products, volatilized higher hydrocarbons, and ammonia, which are recovered in conventional fashion. After coking, the pellets are treated at an elevated temperature in the presence of limited amounts of oxygen and water to convert, via the known water-gas reaction, a substantial proportion of the residual carbon to CO and hydrogen, a portion of the carbon content being oxidized to carbon monoxide to supply the energy requirements of the endothermic water-gas reaction, as well as to heat the mineral constituents to a temperature sufficiently high to produce Portland cement. The resulting solid product, containing the sulfur content of the original coal in solid form, is then cooled and ground to produce Portland cement for use or sale. The gaseous products, all having substantial value as fuel or chemical reactants, are recovered in conventional fashion.
It will be seen that the process of the invention eliminates or substantially reduces two of the major problems encountered in converting coal to fuel and chemical feedstocks, by suppressing the production of corrosive and polluting sulphur-bearing gases during the conversion process, and by producing a solid product which, unlike the valueless ash usually produced when coal is burned, is a valuable Portland cement by-product."
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We note that, because this process binds any Sulfur present in the Coal into the Coal Ash cement product, not only will it prevent polluting emissions of Sulfur compounds, it will enhance the efficiency of any subsequent hydrocarbon syntheses performed with the Carbon Monoxide and Hydrogen formed by the Coal gasification, since, as can be learned for only one example in:
Factors in sulfur poisoning of iron catalysts in Fischer-Tropsch synthesis; "Factors in Sulfur Poisoning of Iron Catalysts in Fischer-Tropsch Synthesis; 1964; Pittsburgh Coal Research Center, Bureau of Mines, U.S. Department of the Interior, Pittsburgh, Pennsylvania; Poisoning of catalysts in the Fischer-Tropsch synthesis by sulfur compounds has been investigated at the U.S. Bureau of Mines as part of its program on the conversion of coal to liquid and gaseous fuels";
Sulfur has long been known to be a poison of hydrocarbon synthesis catalysts.
In sum, we have herein embodied yet another example of Coal conversion technology, wherein the economics, the profitability, of the conversion of Coal into liquid and gaseous hydrocarbons is enhanced, through the co-production of "a valuable Portland cement by-product", while, at the same time, any adverse environmental effects are minimized "by suppressing the production (of) sulphur-bearing gases during the conversion process".
And, separately, the environmental benefits are extended even beyond the prevention of generating solid wastes from a Coal conversion process, by making unnecessary both the separate extraction of natural mineral raw materials and the high expenditure of energy needed for the making of Portland Cement in the conventional way, in a cement kiln.
Top all of that off with increased domestic US employment, a reduction in overseas military entanglements to keep the oil flowing, and preventing our grandchildren from serving a lifetime sentence of indentured economic servitude to OPEC, and, the whole concept seems inarguably attractive.
Too bad, that, in US Coal Country at least, it hasn't yet been given a full and fair public hearing.