Method for extracting gallium from fly ash

Inactive Publication Date: 2013-03-21
CHINA SHENHUA ENERGY CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0044]In the present invention, the sodium salts contained in the electrolyzed solution with a high content can be recycled by evaporation and the evaporated water can be re-used.
[0045]As compared with processes in the prior art, the method according to the present invention is simple, the extraction efficiency of gallium is high, the production coast is low, and the product quality is steady. The circulating fluidized-bed fly ash with high activity is adopted as the raw material for the invention and gallium is extracted from the fly ash via direct acid-leaching process, which saves the step of calcination and activation with presence of sodium carbonate at a very high temperature and thus simplifies the procedures and reduces the production cost. The acid leaching of the fly ash occurs in acid-resistant reactor at a moderate temperature (in the range of 100-200° C.), and thus the leaching efficiency of gallium is high, being 80% o

Problems solved by technology

However, the reserve of gallium is low, only approximately 0.015% in the earth's crust.
Therefore, extraction of gallium is c

Method used

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  • Method for extracting gallium from fly ash
  • Method for extracting gallium from fly ash
  • Method for extracting gallium from fly ash

Examples

Experimental program
Comparison scheme
Effect test

Example

Example 1

[0065]The experimental procedures used in the example are as follows.

[0066](1) Crushing the circulating fluidized-bed fly ash to a size of 200 mesh, removing iron by wet magnetic separation using the vertical magnetic separator as illustrated in FIG. 3, such that the ferric oxide content in the fly ash was reduced to 0.8 wt %; putting the filtered cake of the fly ash obtained after magnetic separation into an acid-resistant reactor and adding industrial hydrochloride acid having a concentration of 37 wt % therein to perform acid dissolving reaction, wherein the molar ratio of HCl contained in the hydrochloride acid to alumina contained in the fly ash was 4.5:1, the reaction temperature was 200° C., the reaction pressure was 2.1 MPa and the reaction time was 1 hour; and then pressure-filtering the discharged reaction product by means of plate-and-frame filter press and washing to yield a hydrochloric leachate having pH of 1.7, wherein the leaching efficiency of gallium from ...

Example

Example 2

[0071]The operation conditions were the same as those of Example 1 except step (1). Step (1) was adjusted as follows:

[0072]Crushing the circulating fluidized-bed fly ash to a size of 150 mesh, removing iron by wet magnetic separation using the vertical magnetic separator as illustrated in FIG. 3, such that the ferric oxide content in the fly ash was reduced to 0.8 wt %; putting the filtered cake of the fly ash obtained after magnetic separation into an acid-resistant reactor and adding industrial hydrochloride acid having a concentration of 28 wt % therein to perform acid dissolving reaction, wherein the molar ratio of HCl contained in the hydrochloride acid to alumina contained in the fly ash was 5:1, the reaction temperature was 150° C., the reaction pressure was 1.0 MPa and the reaction time was 2 hours; and then pressure-filtering the discharged reaction product by means of plate-and-frame filter press and washing to yield a hydrochloric leachate having pH of 1.5, where...

Example

Example 3

[0074]The operation conditions were the same as those of Example 1 except step (1). Step (1) was adjusted as follows:

[0075]Crushing the circulating fluidized-bed fly ash to a size of 200 mesh, removing iron by wet magnetic separation using the vertical magnetic separator as illustrated in FIG. 3, such that the ferric oxide content in the fly ash was reduced to 0.8 wt %; putting the filtered cake of the fly ash obtained after magnetic separation into an acid-resistant reactor and adding industrial hydrochloride acid having a concentration of 20 wt % therein to perform acid dissolving reaction, wherein the molar ratio of HCl contained in the hydrochloride acid to alumina contained in the fly ash was 8:1, the reaction temperature was 100° C., the reaction pressure was 0.1 MPa and the reaction time was 4 h; and then pressure-filtering the discharged reaction product by means of plate-and-frame filter press and washing to yield a hydrochloric leachate having pH of 1.4, wherein t...

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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 (2) to obtain hydrochloric acid leachate; adsorbing gallium in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain the eluent (5) containing gallium; adding sodium hydroxide (6) solution into the eluent containing gallium to react and obtaining sodium metaaluminate solution containing gallium (8); introducing CO2 into the sodium metaaluminate solution containing gallium (8) for carbonation, followed by separating gallium from aluminum and obtaining aluminum-gallium double salt (15) with the gallium to alumina mass ratio being more than 1:340; adding the aluminum-gallium double salt (15) into sodium hydroxide (17) to react, followed by alkalinity-adjustment concentration to obtain alkali solution containing gallium and aluminum; electrolyzing (10) the alkali solution containing gallium and aluminum to obtain metal gallium (11). The method simplifies the process and improves extraction efficiency of gallium.

Description

TECHNICAL FIELD[0001]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.BACKGROUND[0002]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...

Claims

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Application Information

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IPC IPC(8): C25C1/22
CPCC22B3/10C22B3/42C22B3/44C25C1/22C22B7/02C22B58/00C22B7/007B03C1/03B03C1/032B03C1/0335B03C2201/18Y02P10/20
Inventor LING, WENJIANG, YINSHANWEI, CUNDILI, NANGU, DAZHAOGUO, ZHAOHUAYANG, DIANFANCHI, JUNZHOUZOU, PING
Owner CHINA SHENHUA ENERGY CO LTD
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