China Extracts High-Tech Metal from Coal Ash

CN2011073392 METHOD FOR EXTRACTING GALLIUM FROM FLY ASH
We've previously documented the fact that Coal Ash can serve as an exemplary source, an ore, of some needed, even strategic, metals.
And that, in fact, shouldn't be all too surprising when you consider that Coal Ash is, in essence, just a natural mineral that has undergone some extensive preliminary refining and concentration in the boiler furnace of a power plant.
Our reports about the potentials of using Coal Ash as an ore of metals have included, for one example:
West Virginia Coal Association | USDOE Says Coal Ash Could End Aluminum Ore Imports | Research & Development; concerning, among a number of other included references: "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".
Of course, given the fact that China, as we've many times documented, for just one example in:
"The World CTL 2012 Conference takes place on April 17-20, 2012 in China, featuring two World Best: The reference gathering of Coal Conversion experts and managers on April 17-19 in Beijing (and) the visit to the World’s Largest Coal-To-Olefins Plant on April 20 in Baotou (Inner Mongolia)",
not only openly acknowledges the vast potentials for the full employment of their Coal resources, but, seems to rejoice in them, it's not surprising that, as seen in:
West Virginia Coal Association | China Extracts Aluminum Ore from Coal Ash | Research & Development; concerning the report: "'China's Shenhua 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";
they, too, not only recognize the value of Coal Ash as a reservoir of metals, but are engaged in developing the facilities to extract those metals.
And, note in the above the reference made to "a gallium plant"; gallium being another metal, which, as in our report of:
"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";
and, the United States Patent:

"US Patent 4,643,110 - The Recovery of Gallium and Germanium from Coal Fly Ash; 1987; Assignee: Enron, Inc., Texas; A furnace arrangement for the recovery of gallium and germanium from pelletized fly ash";

it's seen that we have also, in the US, acknowledged Coal Ash to be a source of. Which is significant, since, as seen in:
Gallium - Wikipedia, the free encyclopedia; "In 1986, the production was estimated at 40 tons. By 2011 world production of gallium was an estimated 216 metric tons";
due to it's special utility, as explained in the above article, in high-tech electronics and optics applications, demand for Gallium is increasing at an accelerating rate. And, as can be learned from the US Geological Survey, via:
USGS Minerals Information: Gallium; "Gallium is not produced in the United States, and demand is satisfied by imports, primarily high-purity material from France and low-purity material from Kazakhstan and Russia. More than 95% of gallium consumed in the United States is in the form of gallium arsenide (GaAs). Analog integrated circuits are the largest application for gallium, with optoelectronic devices [mostly laser diodes and light-emitting diodes] as the second largest end use";
aside from some relatively minor amount of scrap recovery, we currently have to import all of it we need.
But, as can be learned via:
not only is the price of Gallium, with some fluctuations, steadily increasing, China is a major supplier of it to the world market. And, in line with our above-cited report concerning "China's Shenua to Produce Alumina from Coal Ash", wherein a new China Shenua "alumina refinery", consuming Coal Ash from an integral power generation facility, would include both an "alumina plant and a gallium plant", here, as excerpted from the initial link in this dispatch, is how they might be extracting that Gallium:
"Method For Extracting Gallium From Fly Ash

Publication No.: WO/2011/134402; International Patent Application No.: PCT/CN2011/073392
International Filing Date: April 27, 2011
Applicant: China Shenhua Energy Company, Beijing
Abstract: Disclosed is a method for extracting gallium from fly ash, which comprises the following steps: crushing the fly ash and removing Fe by magnetic separation; then dissolving it by using hydrochloric acid to obtain hydrochloric acid leachate; adsorbing gallium in the hydrochloric acid leachate with macroporous cation resin, followed by eluting to obtain the eluent containing gallium; adding masking agent to mask ferric ion to obtain the eluent containing gallium after masking; adsorbing gallium in the eluent containing gallium after masking with macroporous cation resin, followed by eluting to obtain secondary eluent; adding sodium hydroxide solution into the secondary eluent to react; filtering and removing precipitate after reaction, and then concentrating the filtrate and electrolyzing to obtain metal gallium. The method simplifies the process and improves extraction yield of gallium.

(It may improve the yield; but, for us, as far as our personal comprehension goes, "simplifies the process" is a bit of a stretch. But, as would be indicated via:
Masking agent - Wikipedia, the free encyclopedia; the "masking agent" would just be a chemical that would bind preferentially with the iron, the "ferric oxide", to prevent it from being carried along or separated with the desired Gallium compounds, we take it to be fairly simple chemistry. And, as explained via:
Elution - Wikipedia, the free encyclopedia; the "eluent" is just a solvent used to wash the Gallium compounds off of and away from the ion exchange membrane/filter, the "macroporous cation resin", which is, generically speaking, well-established chemical processing technology we've dealt with at some length in other reports, especially some of those concerning Carbon Dioxide recycling technologies. Such resins are commercially used and available.
The "masking agent" specified by Shenhua, we will tell you, since we won't be reflecting it in our excerpts, as it's disclosed in the course of a very complicated and distracting dissertation is, simply, Vitamin C.)
Technical Field: The present invention relates to an extracted from fly ash metallic gallium, and more specifically, is a fly ash from the circulating fluidized bed method of extraction of metallic gallium.

Background Art: Gallium is a very important semiconductor material, widely used, a very high price in the international market, the market prospect.

(We are editing and condensing here in the extreme. The translation from the original Chinese is very awkward.)

Gallium (is) very difficult to extract (and the major natural) raw material(s) for extraction of gallium (are) zinc sulfide ore and bauxite. Currently, 90% of the world's gallium (is) industrial byproduct of alumina (extraction) from bauxite ... .

In recent years, research has shown that high gallium content in the fly ash in some areas, to meet or exceed the deposit level.

(That is, the relative amount of Gallium in Fly Ash can exceed the relative amount of it in some natural Aluminum ores, from which the Gallium is commercially extracted as a byproduct. Several Chinese national patents, which we don't have access to, and which describe prior art methods of extracting Aluminum ore and Gallium together, from Coal Ash, are cited. This is a well-established concept. Further, some quite extended detail is devoted to the magnetic separation and acid leaching techniques to reduce the Iron content, inasmuch as possible. Not stated is the fact that, as we've documented in other reports, Iron, often in the form of the mineral "magnetite", and other suitable Iron ore minerals, can be recovered from the Coal Ash, either as primary or secondary products, and the Iron content itself subsequently recovered, as was emphasized in our earlier citation of the USDOE report: "Resource Recovery from Coal Residues.)

In the present invention ... said fly ash include, but are not limited to the fly ash from a circulating fluidized bed.

In the present invention (after the specified elution and enrichment, the Ph is adjusted with lye/sodium hydroxide and) electrolysis (is) performed (with an) electrolysis voltage of 4V ... to obtain metallic gallium.

The present invention is used with a high activity of a circulating fluidized bed of fly ash as a raw material, a method of using the direct acid soluble from fly ash leached gallium, sodium carbonate activation of high temperature calcination step is omitted, thus simplifying the process, and reduces the production costs.

(The Disclosure further describes how the process of Gallium extraction prepares the Ash for the follow-on extraction of it's Aluminum content.)

The present invention has a simple process (and) low production costs ... .

Proved by experiments: the device of the present invention, the magnetic separation of iron removal efficiency can be increased more than 20%, the effective removal of iron from 60% to 80%, which greatly ease the follow-up process solution in addition to the pressure of the iron, thereby reducing the cost of production, improve production efficiency.

(It has been determined that this process generates metallic product with a) gallium content of 99.9%."

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We have, obviously, neglected to reproduce the details of the chemistry. It is complex enough to begin with; and, the noted peculiarities inherent in the translation from the original Chinese make it all so obtuse as to be indecipherable to any but those highly skilled in the electrochemical technicalities.

But, a read of the full Disclosure indicates to us that the process, in addition to, as noted above, enabling the follow-on extraction of Aluminum, allows effective recovery of some, or most, "60% to 80%", of the Iron.

And, the sum of it is that Shenhua has devised an integrated technology that, as indicated in our earlier dispatch concerning "China's Shenhua to Produce Alumina from Coal Ash", effects not just the extraction of Aluminum values, but the Gallium and, it seems, the Iron, as well, from Coal combustion residues.

And, again, as with Aluminum, we currently have to import all of the Gallium we use. And, yet again as with Aluminum, if we began extracting Gallium from our Coal Ash, we have enough Coal Ash that we wouldn't have to import any of the metal at all.

The technology is just further evidence that we could and should change the way we look at Coal Ash.

Rather than treating it, or thinking of it, as "waste" from an industrial process, we should - - and are justified in doing so - - start to view it for what it truly is:

A valuable mineral resource; simply an inorganic mineral composed of various metallic and non-metallic elements, some of which can be, and are worth being, extracted and taken to market.

China has, obviously, corrected the

ir thinking on the matter; and, maybe it's time we followed their lead, before they get any further ahead of us