We've many times documented that Coal Ash, the solid byproduct arising from our economically essential use of Coal in the generation of reliable, affordable and abundant electric power, is a valuable resource.
Aside from its established uses in the manufacture of high-performance cement and concrete, it can also serve as an ore of economically and strategically important metals.
Perhaps most notable is the fact that Aluminum can be refined from Coal Ash; a fact, that, as affirmed by the United States Department of Energy, as seen in our report of:
USDOE Says Coal Ash Could End Aluminum Ore Imports | Research & Development | News; 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";
is of some special significance since the USA must now import all of the natural Aluminum ore it refines into virgin Aluminum metal - even though, if we started to treat Coal Ash as an ore of Aluminum, we have enough Coal Ash that we could put an end to those imports. We could be self-sufficient in our supply of Aluminum; and, Coal Ash can be seen and treated, in the US Government's own words, as a "huge" reservoir "of valuable resources".
Just as significantly, as seen our report of:
China Extracts Aluminum Ore from Coal Ash | Research & Development | News; concerning: "China's Shenua to Produce Alumina from Coal Ash; December 19, 2011; China's Shenhua Group began construction Sunday of a coal ash-based alumina refinery in the Inner Mongolia autonomous region, the official Xinhua news agency said. Shenhua plans to invest Yuan 135.8 billion ($21.4 billion) in the project, deputy manager Ling Wen is quoted as having said. Located in the Jungar coal mining area in Ordos city, the project will include a 6.6 GW power plant, an alumina plant and a gallium plant ... . ... All of the plants will use materials recycled from coal burning";
one of our great international economic competitors is starting to take advantage of the value of Coal Ash as an ore of Aluminum, and other metals.
In another report:
US EPA Headquarters Housed in Coal Ash | Research & Development | News; which we titled because of a "sidelight" we included in that report concerning information published by the CertainTeed company, i.e.: "The U.S. Environmental Protection Agency (EPA) recognizes fly ash as an industrial by-product of the coal combustion process in electricity-generating power plants. The EPA supports the beneficial reuse of fly ash in construction applications because it is safe and reduces the amount of coal combustion residue sent to landfill. 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 several construction projects and prominent buildings, including the Ronald Reagan Government Office building, home to the Environmental Protection Agency (EPA) in Washington, D.C.";
but, which report actually concerned:
"United States Patent 4,159,310 - Recovering Aluminum and Other Metal Values from Fly Ash; 1979; Inventors: James Reynolds and Allan Williams, Colorado; Assignee: Public Service Company of New Mexico, Albuquerque, NM; Abstract: A process for recovering aluminum from fly ash containing iron, silicon and titanium which comprises: (a) chlorinating the fly ash in an oxidizing atmosphere to selectively chlorinate and vaporize iron chloride from the remaining chlorides, (b) chlorinating the residue from step (a) in a reducing atmosphere of carbon monoxide, in the presence of added silicon chloride to suppress the chlorination of silicon, and vaporizing the chlorides of aluminum, silicon, titanium, and the residual iron, (c) separating and recovering the vaporized chlorides by selective condensation, and treating the residue of step (b) with sulfuric acid to convert calcium chloride to gypsum, and to regenerate a chloridizing and binder solution for pelletizing fly ash feed. Claims: A process for recovering aluminum from fly ash containing aluminum, iron and (silica) silicon which comprises: chlorinating the material by subjecting it to the action of chlorine at a temperature of about 500C to 1200C. in an oxidizing atmosphere";
we documented one specific version of what became and what was at least once known more generically as the "Hi-Chlor" process for extracting Aluminum and other metal values from Coal Ash.
And, since the "Hi-Chlor" process is noted and figures in some reports we have in process about the recovery of valuable metals from Coal Ash, and since "United States Patent 4,159,310" took a perhaps unnoticed back seat position in that prior report, we wanted herein to reintroduce it, and to give it a more thorough presentation, since the technology it represents will figure in reports to follow about other specific technologies for treating Coal Ash as a unique domestic USA ore of strategic materials.
That said, comment follows excerpts from the initial link in this dispatch to:
"United States Patent 4,159,310 - Process for Recovering Aluminum and Other Metal Values from Coal Ash
Date: June 26, 1979
Inventors: James Reynolds and Alan Williams, CO
Assignee: Public Service Company of New Mexico, Albuquerque, NM\
(https://www.pnm.com/about-pnm; "As the state's largest electricity provider, PNM (Public Service Company of New Mexico) serves more than 500,000 New Mexico residential and business customers in Greater Albuquerque, Rio Rancho, Los Lunas and Belen, Santa Fe, Las Vegas, Alamogordo, Ruidoso, Silver City, Deming, Bayard, Lordsburg and Clayton. We also serve the New Mexico tribal communities of the Tesuque, Cochiti, Santo Domingo, San Felipe, Santa Ana, Sandia, Isleta and Laguna Pueblos. PNM was founded in 1917 as the Albuquerque Gas and Electric Co. and has undergone several transformations, including name changes, in its history. The company sold its natural gas utility to New Mexico Gas Company in 2009. PNM is one of two subsidiaries of PNM Resources, an investor-owned energy holding company.")
Abstract: A process for recovering aluminum from fly ash containing iron, silicon and titanium which comprises: (a) chlorinating the fly ash in an oxidizing atmosphere to selectively chlorinate and vaporize iron chloride from the remaining chlorides, (b) chlorinating the residue from step (a) in a reducing atmosphere of carbon monoxide, in the presence of added silicon chloride to suppress the chlorination of silicon, and vaporizing the chlorides of aluminum, silicon, titanium, and the residual iron, (c) separating and recovering the vaporized chlorides by selective condensation, and treating the residue of step (b) with sulfuric acid to convert calcium chloride to gypsum, and to regenerate a chloridizing and binder solution for pelletizing fly ash feed.
(Note, in the above, that chlorine is recycled to a certain extent within the process, and, that, "gypsum" is generated as well as a byproduct, much as it is already in some cases made from the sulfur-containing constituents in Coal power plant exhaust gas, as in our report of:
Synthetic Gypsum from Coal Power Plant Flue Gas | Research & Development | News; which centers on: "United States Patent 7,776,150 - Process and Apparatus for Handling Synthetic Gypsum; 2010; Assignees: Koppern Equipment Company, NC, and Giant Cement Company, SC; Abstract: Method and apparatus for converting wet synthetic gypsum from a flue desulphurization process (FGD) to easily handled and metered briquettes".
Such gypsum, as noted in that report, already has significant commercial usage in the making of both "dry wall" panels, or "wallboard", and Portland-type cement.)
Claims: A process for recovering aluminum from fly ash containing aluminum, iron and (silica) silicon which comprises:
(a) chlorinating the material by subjecting it to the action of chlorine at a temperature of about 500 - 1200 C in an oxidizing atmosphere in the presence of added oxygen in an amount equal to about 5-100 volume percent of the chlorine to selectively vaporize iron as iron chloride;
(b) chlorinating the residue from step (a) by subjecting it to the action of chlorine at a temperature of about 500 - 1200 C. in a reducing atmosphere in the absence of solid carbon to vaporize the chlorides of aluminum (tatanium) and silicon; and
(c) separating and recovering the formed (reacted) chlorides from the vapors by selective condensing.
The process ... in which the reductive chlorination of step (b) is performed in the presence of carbon monoxide as a reducing agent.
(Keep in mind, that, as seen for just one example in our report of:
Bayer Improves Coal + CO2 = Carbon Monoxide | Research & Development | News; concerning: "United States Patent 7,473,286 - Carbon Monoxide Generator; 2009; Inventor: Herbert Blaschke, et. al., Germany; Assignee: Bayer Material Science, AG, Germany; Abstract and Claims: A generator including a double-chamber lock (and other features, as detailed, and) further comprising a desulfurizing device. Background and Field: The present invention relates to a novel generator for the reaction of carbon-containing raw materials and also to an improved process for the production of carbon monoxide gas (CO gas) having a high degree of purity using such a generator. Carbon monoxide gas is frequently produced in the art by means of a continuous process in which carbon-containing raw materials are reacted with oxygen and carbon dioxide ... . An object of the present invention was ,,, to provide a continuous process for the production of CO gas by the gasification of coal using the generator according to the invention, which process does not exhibit the disadvantages (of the) described (prior art). A further object of the invention was to produce a CO gas having a purity of greater than 96%, preferably from 97 to 98%. In contrast to other processes of the prior art, the reaction in the combustion zone is controlled by injecting CO2 and O2 into the furnace together through the (described apparatus) ... so that the (O2) is diluted by the stream of CO2 gas. Adequate mixing of the gases is achieved by means of suitable mixing devices (as suggested). In this manner, the two reactions that take place ..., C + O2 (and) CO2 + C ... are concentrated in a single controllable combustion zone and (by) varying the ratio of CO2 to O2 in the gas mixture that is fed in, according to the type of fuel and the properties of the fuel, the reaction temperature can be controlled (as well as) the degree of purity of the CO gas. Suitable fuels which meet the (requirements) and which can be reacted successfully in terms of technology and economy to CO gas in the process described herein are, for example ... coal coke";
the technology exists to make nearly pure "carbon monoxide", perhaps for use "as a reducing agent" in the process of our subject by reacting "CO2 gas" with some of our abundant Coal.)
The process ... in which the reductive chlorination ... is performed at about 1050 C in the presence of silicon tetrachloride at a concentration of about 3 volume percent (and) wherein the fly ash contains calcium and in which the material (residue of solid chlorides) ... is reacted with sulfuric acid to produce disposable gypsum.
The process ... wherein the fly ash contains calcium and in which the material (residue of solid chlorides) from ... remaining after vaporization is reacted with sulfuric acid to produce disposable gypsum and to form hydrochloric acid (and) in which the fly ash feed is pelletized ... and bentonite is used as a binder for the pellets.
The process ... in which titanium is present in said fly ash and it is chlorinated ... and separated and recovered in accordance with (previous steps).
(Note, in the above final claim, that, as in our previous report, cited above, concerning: "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"; "titanium" metal can exist, as well, in Coal Ash in amounts high enough to make its recovery worthwhile, and the process of our subject, "United States Patent 4,159,310 - Process for Recovering Aluminum and Other Metal Values from Coal Ash", enables it's extraction, along with Aluminum, from Coal Ash.)
Background and Field: Large quantities of fly ash carried by the combustion products of power plants burning pulverized coal exist throughout the country and more is being created by operation of these plants. This accumulation ... represents a waste of metal values, particularly aluminum, as a typical fly ash contains up to fourteen percent aluminum by weight. Lesser amounts of iron, titranium and other useful metals are present in fly ash.
No satisfactory process exists for economically recovering aluminum from fly ash having the required purity for commercial sale because of the difficulty of separating it from other metals present in the fly ash, particularly, iron. Separation through the chlorination route to recover aluminum as aluminum chloride looks attractive, however, the process must produce an aluminum chloride of substantial purity. For example, purity requirements for aluminum chloride feed material to an Alcoa-type aluminum cell limit the Fe2O3 content of the feed to 0.03 percent. Furthermore, in the chlorination process, the chlorination of unwanted metals, such as silicon, must be suppressed to restrict the consumption of chlorine; otherwise, the process becomes prohibitively expensive.
A further problem involved in recovering the metal values from fly ash through the chlorination route, is the disposal of alkali and alkaline earth metal chlorides remaining in the final residue. Accordingly, it is a principal object of this invention to provide a method for recovering aluminum of substantially high purity from fly ash ... . It is another object of this invention to provide a method for suppressing the chlorination of silicon when recovering aluminum as aluminum chloride from fly ash by chlorination. It is a further object of this invention to provide a method for the disposal of alkali and alkaline earth metal chlorides remaining in the final residue resulting from the chlorination of fly ash to recover aluminum as aluminum chloride.
Summary: A process for recovering aluminum from fly ash ... by the chlorination route which comprises first separating iron from the remaining metals by selectively chlorinating the iron in an oxidizing atmosphere (about 5 to 100 percent added oxygen by volume) and vaporizing it followed by chlorinating the residue containing the remaining metals including aluminum, silicon, titanium, alkali and alkaline earth metals, and some iron, in a reducing atmosphere of carbon monoxide in the absence of solid carbon to suppress the chlorination of silicon, vaporizing the chlorides of aluminum, silicon, titanium and the remaining iron, separating a recovering the vaporized chlorides by selective condensation, and treating the final residue with sulfuric acid to convert calcium chloride to disposable gypsum with simultaneous regeneration of a dilute HCl solution for purposes of prechloridizing the fly ash feed and also providing a suitable binder for pelletizing the fly ash feed.
Improvements are forming the feed material into carbon-free briquettes, and introducing silicon chloride into the reductive chlorination step to further suppress the chlorination of silicon.
(An) effective and economical process (is) provided for recovering substantially pure aluminum, as well as other metal values, from fly ash by the selective chlorination and condensing procedure (as disclosed and illustrated). The process additionally provides a means for disposing of the alkali metal and alkaline earth chlorides in the residue with regeneration of hydrochloric acid which can be reused in the process. A maximum use of by-products and excess heat energy is achieved by the process of the invention".
Although presented as a method of extracting Aluminum from Coal Ash, as the full disclosure of "United States Patent 4,159,310 - Process for Recovering Aluminum and Other Metal Values from Coal Ash" makes clear, Iron and Titanium can also be recovered on a practical basis from Coal Ash in the "Process".
And, we'll note in passing, that, as seen in:
http://www.freepatentsonline.com/1147832.pdf; "United States Patent 1,147,832 - Production of Aluminum Chloride, 1915; Virginia Laboratory Company of New York";
which is disclosure of a very similar method of using chlorine to extract Aluminum from both Aluminum ore, "bauxite", and alumino-silicate "clays" which are very similar in chemical composition to Coal Ash, the process of our subject is building on technology for refining Aluminum from Coal Ash that, like the technology for, as seen in:
converting the CO2 byproduct of our use of Coal in generating abundant and economically essential electric power into substitute, fracking-free natural gas Methane, is fully one century old. And, as we will see in reports to follow, the subsequent process embodied in our subject, "US Patent 4,159,310 - Process for Recovering Aluminum and Other Metal Values from Coal Ash", has itself led to further developments, which result in yet another competitive technical route for utilizing Coal Ash as an accessible, practical store of both "Metal Values" and synthetic mineral commodities, such as the byproduct "gypsum".
And, the sum of it all is this: If we as a people had the quality of heart to make the effort to ensure such knowledge was made broadly known, and the strength of will to reduce that knowledge to practice, not only would some of the arrows aimed at our use of Coal in the generation of electrical power be blunted, but, the United States of America itself could become even freer, stronger, more economically independent, with more of its citizens very productively employed in industries founded on the consumption of the byproducts arising from the use of America's far and away largest domestic energy resource: Coal.