Energy Citations Database (ECD) - - Document #21058939
First, referring to our headline, the "high-tech metal" we specifically intend is "Germanium".
And, you might well be inspired to ask:
What the heck is Germanium, anyway; and, why should I care?
Well, as has been explained to us, Germanium is a semi-metallic element that belongs to the same "family", or Group on the Periodic Table of Elements, as Carbon and Silicon.
And, like Silicon, it is a semi-conductor, only, in certain ways, better. The only reason, in fact, that we don't have a "Germanium Valley" as opposed to a "Silicon Valley" is because it ain't that easy to come by.
All early transistors, in fact, were based on Germanium; and, it wasn't until better refining techniques were developed for Silicon, and, even though it isn't quite as good as Germanium, we became able to obtain Silicon in high-enough purity from, essentially, beach sand, that Germanium was displaced by Silicon in the manufacture of transistors and diodes and such.
For some background, we recommend our old friend, the Wikipedia, as via:
Germanium - Wikipedia, the free encyclopedia;
which, in a well-documented piece replete with reference links, explains that Germanium, though isolated and named in the late 1800's, didn't really come into demand until WWII, when it's superior properties were exploited in some then-advanced electronics applications, especially radar.
Nowadays, it's unique properties have found use in other high-tech applications such as night vision devices and fiber optics, mostly, again, because of its expense, by the military, who can afford to pay for the better performance.
NASA, too, makes use of it in high-performance earth satellite and planetary exploration devices.
Though, in total amount of occurrence, not that "rare", - Germanium is broadly dispersed - it can, with one exception, only be recovered in a genuinely commercial way as a by-product from the mining of other metals, such as Lead, Zinc and Copper.
However, Russia and China have discovered that "one exception", and have begun to exploit it:
They are extracting Germanium from Coal fly ash.
Ancient processes caused Germanium to become somewhat concentrated in certain Coal seams, and, once the Carbon has been combusted for whatever purpose, the Ash from that Coal contains recoverable Germanium in concentrations higher than the Lead and Zinc ores from which it is currently being produced.
Others, too, have discovered that potential, as seen in excerpts from the initial link in this dispatch to:
"Hydrometallurgical Recovery of Germanium from Coal Gasification Fly Ash. Solvent Extraction Method
Industrial and Engineering Chemistry Research; Journal Volume: 47; Journal Issue: 9; 2008
Authors: F. Arroyo, et. al.; University of Seville, Spain
Abstract: This article is concerned with a simple hydrometallurgical method for the selective recovery of germanium from fly ash (FA) generated in an integrated gasification with combined cycle (IGCC) process. The method is based on the leaching of FA with water and a subsequent concentration and selective separation of germanium by a solvent method. Regarding the leaching step, the different operational conditions studied were liquid/solid (L/S) ratio and time of contact. The solvent extraction method was based on germanium complexation with catechol (CAT) in an aqueous solution followed by the extraction ... with an extracting organic reagent diluted in an organic solvent. The main factors examined during the extraction tests were aqueous phase/organic phase (AP/OP) volumetric ratio, aqueous phase pH, amounts of reagents, and time of contact. Germanium extraction yields were higher than 90%."
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First of all, "extraction yields ... higher than 90%" are pretty darned good, no matter what it is you're after.
So encouraged were the Spanish scientists by those initial findings that they took the process to a larger scale, as seen in:
Energy Citations Database (ECD) - - Document #21176911
"Hydrometallurgical Recovery of Germanium from Coal Gasification Fly Ash: Pilot Plant Scale Evaluation
Industrial and Engineering Chemistry Research; Volume: 48; Journal Issue: 7; 2009
Authors: F. Arroyo, et. al.; University of Seville, Spain
Abstract: In this article, a hydrometallurgical method for the selective recovery of germanium from fly ash (FA) has been tested at pilot plant scale. The pilot plant flowsheet comprised a first stage of water leaching of FA, and a subsequent selective recovery of the germanium from the leachate by solvent extraction method. The solvent extraction method was based on Ge complexation with catechol in an aqueous solution followed by the extraction of the Ge-catechol complex ... with an extracting organic reagent (trioctylamine) diluted in an organic solvent (kerosene), followed by the subsequent stripping of the organic extract. The process has been tested on a FA generated in an integrated gasification with combined cycle (IGCC) process. The paper describes the designed 5 kg/h pilot plant and the tests performed on it. Under the operational conditions tested, approximately 50% of germanium could be recovered from FA after a water extraction at room temperature."
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All of that, of course, sounds very advanced and modern. But, the Spanish scientists were only following in the footsteps of our good old US Bureau of Mines, since they had long ago stumbled onto such potentials, as evidenced by:
Energy Citations Database (ECD) - - Document #7342110
"Extraction of Germanium and Gallium from Coal Fly Ash
Technical Report BM-RI-6940; OSTI ID: 7342110; April, 1966
R.F. Waters, et. al.; Bureau of Mines, Rolla, MO. Rolla Metallurgy Research Center".
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The above reference indicates other Coal ash metal extraction potentials, as well, obviously; and, "Gallium", too, is some nifty stuff to have a little of, with more to be learned via:
Gallium - Wikipedia, the free encyclopedia; wherein we're told that Gallium finds use in: "semiconductors (as gallium arsenide), microwave circuitry and infrared applications ... diodes ... and diode lasers".
However, it's primarily Germanium we're focused on herein; and, somewhat in line with the potentials documented above, a once-major player in the US energy industry recognized those potentials for exploiting Coal fly ash as a source of it.
First, though, lest you be influenced negatively by the corporate source, and rights assignee, of the two United States Patents we submit, following, we remind you that, as seen in:
Enron - Wikipedia, the free encyclopedia; the now-infamous Enron, of, as in: THE ENRON SCANDAL;
was, before they caught a dose of the high-tech broadband financial vapors and took flight from their basic roots as an energy, especially natural gas, supply company, were a truly significant member of the Texas petroleum and pipeline industrial community.
In other words, before they lost their financial senses, they were very reputable; and, very competent in some technologies related to the utilization of natural resources.
That competency, as it relates to the extraction of a valuable product from what most see as a noxious waste, was affirmed by our own United States Government experts in:
"United States Patent: 4643110 - The Recovery of Gallium and Germanium from Coal Fly Ash
Date: February, 1987
Inventors: Bohdan Lisowyj, et. al., NE and MO
Assignee: Enron, Inc., Houston, TX
Abstract: A furnace arrangement utilizes a single vertically disposed shaft furnace incorporating the features of pellet drying and hardening, oxidizing heat-up, reducing roast and gas separation. The upper portion of the furnace dries and hardens "green" pellets while at the same time subjecting them to an oxidizing atmosphere and temperature increase. A stack of the pellets slowly moves downwardly through a transition zone to a reducing atmosphere in a lower portion of the furnace. A heated reducing gas circulates through this lower portion and out of the furnace through a recovery system of the furnace arrangement. After the sublimate carried by the reducing gas is removed, the reducing gas is supplemented and returned to the lower portion of the furnace to again produce a reducing atmosphere. A smaller branch of cooled reducing gas enters the lower portion of the furnace adjacent the bottom to cool the pellet residue immediately prior to removal from the furnace.
Claims: A furnace arrangement for the recovery of gallium and germanium from pelletized fly ash, comprising: a vertically disposed shaft furnace; said furnace having an upper portion with means for heating the contents thereof in an oxidizing atmosphere; said furnace upper portion adapted to receive a continuous charge of "green" pelletized fly ash; said furnace having a lower portion with means for subjecting the contents thereof to a reducing atmosphere.
Background and Field: The present invention relates generally to a furnace arrangement utilized in recovering trace minerals from coal fly ash, and more specifically to an improved furnace arrangement incorporating oxidizing heat-up, reducing roast and gas separation in a single furnace.
In utility and industrial boilers burning coal, fly ash is produced. Electrostatic precipitators, wet scrubbers, bag houses or other recovery equipment are used to remove the fly ash particulates from the combustion gases. In general, the fly ash is composed of fine grained particles having a silica-alumina base with certain of trace metals concentrated on the surfaces of the particles. Some of these trace metals are valuable, including molybdenum, tungsten, nickel, gallium, and germanium.
Numerous attempts have been made in the past to recover certain of the trace metals present in fly ash, particularly gallium and germanium. One such method is the sublimation of these trace metals. The process involved the following steps: (1) the fly ash is pelletized and then dried and hardened so that the pellets can be stacked on top of each other within the furnace; (2) the pellets are then heated in a furnace in an oxidizing atmosphere; (3) the pellets are then subjected to a reducing atmosphere, causing the gallium and/or germanium to sublime and be carried away by the reducing gas--thereby separating the sublimate from the pellet residue; (4) the sublimate is then recovered from the reducing gas, the reducing gas being reused in the reducing atmosphere; and (5) the pellet residue is cooled and removed from the furnace.
It is therefore an object of this invention to provide an improved furnace arrangement for the recovery of trace metals from fly ash.
Another object of this invention is to provide a furnace arrangement capable of continuous operation in the recovery of the trace metals from fly ash.
Yet another object of the invention is to reduce the number of separate steps necessary to recover trace metals from fly ash, thereby decreasing the cost and improving the efficiency of the process.
Summary: A furnace arrangement is described which utilizes a single vertically disposed shaft furnace incorporating the features of pellet drying and hardening, oxidizing heat-up, reducing roast and gas separation. The upper portion of the furnace dries and hardens "green" pellets while at the same time subjecting them to an oxidizing atmosphere and temperature increase. A stack of the pellets slowly moves downwardly through a transition zone to a reducing atmosphere in a lower portion of the furnace. A heated reducing gas circulates through this lower portion and out of the furnace through a recovery system of the furnace arrangement. After the sublimate carried by the reducing gas is removed, the reducing gas is supplemented and returned to the lower portion of the furnace to again produce a reducing atmosphere. A smaller branch of cooled reducing gas enters the lower portion of the furnace adjacent the bottom to cool the pellet residue immediately prior to removal from the furnace."
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Now, truth to tell, they don't exactly specify what their "reducing atmosphere" might consist of, but, interestingly, composed as it is primarily of various hot gaseous oxides, the Coal combustion exhaust gases might just qualify.
Regardless of that, some elevated temperatures are required, and, of course, there will be, as we've beaten to death in a number of previous reports, a large amount of useable, otherwise waste, heat available at a Coal-fired power generation facility.
In any case, Enron continued their, what was in this case, good work, and, were subsequently awarded:
"United States Patent: 4678647 - Recovery of Gallium and Germanium from Coal Fly Ash
Date: July, 1987
Inventors: Bohdan Lisowyj, et. al., NE and MO
Assignee: Enron, Inc., Houston, TX
Abstract: A method is disclosed for recovering gallium and/or germanium from fly ash which comprises pelletizing the fly ash, treating the pellets in the presence of an oxidizing gas at a temperature of from about 900C to just below the fusion temperature of the pellets, treating the pellets in the presence of a reducing gas at the same temperature range, and recovering gallium and/or germanium suboxides from the gas.
Claims: A method of recovering gallium and germanium from fly ash which comprises: pelletizing the fly ash, then: heating the pellets in an oxidizing atmosphere at a temperature of from about 900.degree. C. to just below the fusion temperature of the pellets, the temperature being high enough to remove trace elements volatile in an oxidizing atmosphere, then: treating the pellets in a reducing atmosphere at a temperature of from about 900.degree. C. to just below the fushion temperature of the pellets to reduce the gallium and germanium oxides to suboxides and cause them to sublime, and then: recovering the gallium and germanium suboxides from the gas.
The method ... wherein the fly ash is treated prior to pelletizing so as to be concentrated in gallium and germanium content and decreased in iron content."
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We close our excerpts right there so that we can emphasize what might be an important point:
The Coal "fly ash" must first be "concentrated in gallium and germanium content" by a process that results in a "decreased ... iron content".
And, we remind you, that, as documented in:
Iowa Mines Metals from Coal Ash for the USDOE | Research & Development; concerning, in part: "United States Patent 4,386,057 - Recovery of Iron Oxide from Coal Fly Ash; 1983; Assignee: The United States of America; The U.S. Government has rights in this invention pursuant to Contract No. W-7405-ENG-82 between the U.S. Department of Energy and Ames Laboratory; A high quality iron oxide concentrate, suitable as a feed for blast and electric reduction furnaces is recovered from pulverized coal fly ash";
our own US Government owns a technology which could, on a commercial and profitable basis, enable us to remove the Iron from Coal ash, in the form of a "feed for blast and electric reduction furnaces" and the production of Iron; and, thus, render the Coal ash more suitable for use in the Enron processes of "United States Patent 4,678,647" and "United States Patent 4,643,110", and, the consequent production of the valuable, and otherwise somewhat scarce, high-tech elements Germanium and Gallium from the Coal ash.
Further, to just pile it on, as seen in:
Scientists Convert Coal Ash to Cement | Research & Development; and, in:
US EPA Headquarters Housed in Coal Ash | Research & Development;
even once all of the metal values have been extracted from Coal ash, the remaining mineral residues still have worth, both as a raw material for the making of Portland-type cement; and, then, as a filler, an aggregate, for that cement to make structural concrete.
All of the above serves to confirm that the Ash which results from our productive and vital use of Coal, just, as seen in:
USDOE Converts CO2 to Gasoline | Research & Development; concerning the USDOE's own: "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";
like the Carbon Dioxide which also arises, in a small way relative to natural sources of emission, from our productive and vital use of Coal; can, and should, be viewed as a valuable raw material resource; a resource whose full and productive use could free us from economic losses arising from foreign exchange with sometimes unfriendly exporters of metal ores and fuels, and, from underemployment in the industrial heart of the United States of America: those states, like West Virginia, Pennsylvania and Ohio, that are the core of United States Coal Country.