United States Patent Application: 0130081954

As we earlier reported, via:

West Virginia Coal Association | China Extracts Aluminum Ore from Coal Ash | Research & Development; concerning the news report: "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";

China is extracting Aluminum ore from Coal Ash - which, as we've many times documented, is a rich source of that metal. And, concurrently with the Aluminum recovery, China is also mining Coal Ash for the strategically important metal, Gallium, which, as we've documented, has unique utility in electronics and optics applications, perhaps especially in solar cells.

And, via our report of:

West Virginia Coal Association | China Extracts High-Tech Metal from Coal Ash | Research & Development; concerning the international, or "World" patent application: "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";

we saw that China has established their own technology for such Gallium recovery from Coal power plant Fly Ash, in a process, that, as we take it, differs in some important respects from others, related, such as that, for one example, seen in our report of:

West Virginia Coal Association | Coal Ash a Superior Source of High-Tech Metal | Research & Development; concerning, in part: "United States Patent 4,678,647 - Recovery of Gallium and Germanium from Coal Fly Ash; 1987; 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";

developed in the United States of America.

In any case, via excerpts from the initial and one following link in this dispatch, we see that China's Shenhua, who produce more Coal than anyone else in the world, have disclosed, and separately secured their rights to, their technology for extracting the important metal, Gallium, from Coal Ash in the United States of America, as well:

"United States Patent Application 20130081954 - Method for Extracting Gallium from Fly Ash

Patent US20130081954 - Method for extracting gallium from fly ash - Google Patents

METHOD FOR EXTRACTING GALLIUM FROM FLY ASH - CHINA SHENHUA ENERGY COMPANY LIMITED

Date: April 4, 2013

Inventor: Dazhao Gu, et. al., China

Assignee: China Shenhua Energy Company, Ltd., 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 hydrochloride acid to obtain hydrochloric acid leachate; adsorbing gallium contained in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain an eluent containing gallium; adding masking agent to mask ferric ion to obtain an eluent containing gallium after masking; adsorbing gallium in the eluent containing gallium after masking with macro-porous cationic resin, followed by eluting to obtain a secondary eluent; adding sodium hydroxide solution into the secondary eluent to react; filtering and removing precipitates after reaction, and then concentrating the filtrate and electrolyzing to obtain metal gallium. The method simplifies the process and improves extraction efficiency of gallium.

Claims:  A method for extracting gallium from fly ash, comprising the following steps:

a) crushing the fly ash to a size of 100 mesh or smaller, removing iron by wet magnetic separation such that the ferric oxides content in the fly ash is reduced to 1.0 wt % or less, then adding hydrochloride acid into the de-ironed fly ash for acid-leaching reaction, and subjecting the reaction product to solid-liquid separation, so as to yield a hydrochloric leachate having a pH value in the range of 1-3;

b) cooling the hydrochloric leachate till its temperature is 90 C, then pumping the hydrochloric leachate into a column loaded with JK008 Resin to enrich gallium, (according to specified processing conditions).

(BEIJING TRI-HIGH MEMBRANE TECHNOLOGY CO., LTD-Products; "JK008:uniform-pore strong acid phenylethtlene cation exchange resin".)

c) masking ferric ions in the gallium-containing eluent by a masking agent followed by passing the masked eluent through the column; eluting the column with water or hydrochloride acid as an eluting agent when the adsorption reaches saturation to obtain a second eluent; and:

d) adding an alkali solution into the second eluent, removing precipitates by filtering after reaction, and concentrating the filtrate till both gallium content and sodium hydroxide content are (as specified), then electrolyzing the concentrated filtrate to obtain metal gallium ... .

Background and Field: The present invention relates to a method for extracting metal gallium from fly ash and in particular relates to a method for extracting metal gallium from circulating fluidized-bed fly ash.

(Shenhua, in the full Disclosure, do go into detail about the different Coal combustion techniques, and how different methods of Gallium extraction would respectively apply. As we reference, further on.) 

Gallium is an important semiconductor material and widely used. The price of gallium is very high in the international market and thus gallium has a bright prospect. However, the reserve of gallium is low, only approximately 0.015% in the earth's crust. Gallium almost does not form minerals, but exists with other minerals in form of isomorphism. Therefore, extraction of gallium is considerably difficult. Gallium is often found in conjunction with aluminum and zinc in minerals in nature. As such, sulfide deposits of zinc and bauxite ore serve as a primary source of the extraction of gallium. Nowadays, more than 90% of gallium in the world is extracted from the by-product of alumina industry in which bauxite is used as a main raw material. The mother liquid used for the enrichment and separation of gallium is the mother liquid obtained from carbon precipitation (or seed precipitation) during the process for producing alumina.

The recent studies have shown that the fly ash obtained from some places contains a large amount of gallium which even overpasses the gallium level of mineral deposit.

As compared with the gallium contents of other resources, the fly ash deserves to be extracted for metal gallium as a raw material. In light of different conditions of calcinations, the fly ash is classified into pulverized coal-fired boiler fly ash and circulating fluidized-bed fly ash.

Summary: The object of the invention is to provide an improved method for extracting metal gallium from circulating fluidized-bed fly ash.

The gallium content in the obtained product was measured to be 99.9%."

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The above process, as noted by Shenhua, is intended specifically for the extraction and recovery of Gallium "from fluidized-bed fly ash". We've previously discussed the differences between fluidized bed Coal combustion and conventional pulverized Coal-fired boilers. In general, the temperatures seen in fluidized bed Coal combustion are lower; and, different methods are needed to extract Gallium from Coal Ash produced from pulverized Coal combustion units, like those disclosed in our above-cited report:

West Virginia Coal Association | Coal Ash a Superior Source of High-Tech Metal | Research & Development; which also concerns: "United States Patent 4,643,110 - The Recovery of Gallium and Germanium from Coal Fly Ash; 1987; 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".

More about the different Coal combustion processes can be learned via:

NETL: Coal-Fired Power Plants (CFPPs); and:

Fluidized bed combustion - Wikipedia, the free encyclopedia; and:

Pulverized coal-fired boiler - Wikipedia, the free encyclopedia.

Fluidized Bed Combustion is growing in favor, as you will discover in the above references, since the lower temperatures also reduce production of objectionable Nitrogen Oxides, and fluidized bed boilers are thus considered inherently less polluting.

And, technology for the recovery of metals, like Gallium, via processes like that disclosed in the above "United States Patent Application 20130081954 - Method for Extracting Gallium from Fly Ash", as opposed to processes like that disclosed in, for instance, "United States Patent 4,643,110 - The Recovery of Gallium and Germanium from Coal Fly Ash", might be becoming more applicable as our fleet of Coal-fired power plants evolves.

In any case, Shenhua's process of "United States Patent Application 20130081954" is coupled in some ways with their companion technology, one with an intriguing twist, disclosed via:

"United States Patent Application: 0130068628 - Method for Extracting Gallium from Fly Ash

Patent US20130068628 - Method for extracting gallium from fly ash - Google Patents

METHOD FOR EXTRACTING GALLIUM FROM FLY ASH - CHINA SHENHUA ENERGY COMPANY LIMITED

Date: March 21, 2013

Inventors: Wen Ling, et. al., China

Assignee: China Shenhua Energy Company, Ltd., 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 hydrochloride acid  to obtain hydrochloric acid leachate; adsorbing gallium in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain the eluent containing gallium; adding sodium hydroxide solution into the eluent containing gallium to react and obtaining sodium metaaluminate solution containing gallium; introducing CO2 into the sodium metaaluminate solution containing gallium for carbonation, followed by separating gallium from aluminum and obtaining aluminum-gallium double salt with the gallium to alumina mass ratio being more than 1:340; adding the aluminum-gallium double salt into sodium hydroxide to react, followed by alkalinity-adjustment concentration to obtain alkali solution containing gallium and aluminum; electrolyzing the alkali solution containing gallium and aluminum to obtain metal gallium. The method simplifies the process and improves extraction efficiency of gallium.

(The above-specified use of Carbon Dioxide is, of course, the interesting twist in all of this. But, we're not able to conjecture how large, or how permanent, such consumption of CO2 might be. However, we remind you, that, as seen in:

West Virginia Coal Association | WVU March 28, 2013, Economical Harvesting of Flue Gas CO2 | Research & Development; concerning: "United States Patent Application 20130078172 - Layered Solid Sorbents for Carbon Dioxide Capture; 2013; Inventors: Bingyun Li, et. al.; Assignee: West Virginia University Research Corporation, Morgantown; Abstract: A solid sorbent for the capture and the transport of carbon dioxide gas is provided ... . Government Interests: Certain embodiments of this invention were made with Government support in conjunction with the National Energy Technology Laboratory, Pittsburgh, Pa., under RES contract number DE-FE0004000 awarded by the U.S. Department of Energy. The Government may have certain rights in the invention. A method of capturing carbon dioxide from a pollutant source";

we are getting better at harvesting CO2, for whatever use in which we might wish to employ it.)

Claims: A method for extracting gallium from fly ash, comprising the following steps:

a) crushing the fly ash to a size of 100 mesh or smaller, removing iron by wet magnetic separation, such that the ferric oxides content in the fly ash is reduced to 1.0 wt % or less, then adding hydrochloride acid into the de-ironed fly ash to perform an acid-leaching reaction, and subjecting the reaction product to solid-liquid separation to yield a hydrochloric leachate having a pH value in the range of 1-3;

b) adsorbing gallium in the hydrochloric leachate by passing the same through a column loading with a macro-porous cationic resin; eluting the column with water or hydrochloride acid as an eluting agent when the adsorption reaches saturation to obtain a gallium-containing eluent;

c) adding sodium hydroxide solution into the gallium-containing eluent to react, separating precipitates after reaction by filtration to obtain a gallium-containing sodium metaaluminate solution;

d) subjecting the gallium-containing sodium metaaluminate solution to carbonation by introducing carbon dioxide therein, and then separating gallium from most aluminum to obtain a gallium-aluminum double salt with the mass ratio of gallium to alumina being more than 1:340; and:

e) adding the gallium-aluminum double salt into a sodium hydroxide solution, subjecting the reactant to evaporation and concentration to obtain a base solution containing gallium and aluminum with the contents of gallium and alumina (as specified), and then electrolyzing the base solution to obtain metal gallium ... .

(Note, in the above, that "alumina" would be left after "electrolyzing the base solution to obtain metal gallium". with what should be clear implications for the follow-on processing to obtain more Aluminum ore from the Coal Ash. This Disclosure, as does that of the above "US Patent Application 20130081954", also goes into considerable detail explaining the recovery of Iron values from the Ash as an integral component of the processing for Gallium recovery.)

Summary: The object of the invention is to provide an improved method for extracting metal gallium from circulating fluidized-bed fly ash.

The gallium content in the obtained product was measured to be 99.9%."

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We'll do us all a favor and forgo reproduction of all the technical minutiae. We'll let the final statement that Gallium at a purity of "99.9%" can be recovered from Coal Ash, and might well be being so recovered at Shenhua's Coal Ash Aluminum refinery in "the Inner Mongolia autonomous region", suffice as summary.

And, should you read our full reports, as cited above, concerning that refinery, you will discover that the remaining Coal Ash material, after extraction of at least Aluminum and Gallium, is being sent on to a Cement kiln/factory for, ultimately, complete consumption and utilization.

China, obviously, views Coal Ash as an accessible and rather immensely valuable mineral resource.

Wouldn't it be in the best national interests of the United States of America if we all adopted the same point of view?

West Virginia Coal Association - PO Box 3923 - Charleston, WV 25339 | 304-342-4153 | website developed by brickswithoutstraw