Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group iiia metal or beryllium
Reexamination Certificate
2000-01-12
2001-11-20
Bos, Steven (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group iiia metal or beryllium
C423S147000, C205S564000
Reexamination Certificate
active
06319483
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for separating and concentrating gallium or indium from gallium- and indium-containing solutions.
2. Description of the Related Art
Gallium, which is a metal element obtained in trace amounts as a byproduct of zinc or aluminum smelting, is widely used in compound semiconductors. In the field of compound semiconductors, high purity gallium purified to 6N (99.9999%) or higher is used in the production of GaAs, and GaP, which are, in turn, used for light-emitting diodes, ICs, LSIs, and the like. Similar to gallium, indium is a metal element obtained in trace amounts as a byproduct of zinc or aluminum smelting and mostly used as ITO to form transparent electrode films for liquid crystals.
In conventional practice, ion exchange, solvent extraction, and other techniques are used to selectively separate gallium and indium from solutions containing traces of gallium and indium, and to concentrate these elements. For example, the method disclosed in Japanese Unexamined Patent Application (Kokai) 59-193230 is known as such an ion-exchange technique. According to this technique, a solution containing traces of gallium and indium is passed through a layer of chelating ion-exchange resin under an appropriate pH, the gallium and indium are selectively adsorbed, and these elements are then eluted using a mineral acid.
The following method is also well known as solvent extraction technique: a carboxylic acid-based or phosphoric acid-based chelate extraction chemical is added to an organic solvent, the pH of the aqueous phase is adjusted, and the product is brought into close contact with the aforementioned organic solvent, whereby the gallium and indium in the aqueous phase are selectively extracted as chelates into the organic phase.
The above-described ion-exchange technique, however, requires resin columns and other bulky equipment, irrespective of the recovery volume of gallium and indium. This technique is also disadvantageous in that when large amounts of iron, aluminum, and other impurities are present, failure to remove them in advance will lower the removal efficiency of the resin, block the resin column, and the like.
Solvent extraction is disadvantageous in that large amounts of organic chelating agents and organic solvents are needed for the reactions, so high running costs are incurred and explosion-proof equipment must be used because of safety considerations, resulting in much higher costs in terms of initial investment.
Thus, all these conventional methods are difficult to integrate into future industries in terms of cost, and recovery of trace amounts of gallium and indium at minimal cost is desired.
SUMMARY OF THE INVENTION
It is an object of the present invention to make it possible to recover gallium and indium efficiently and at a low cost from solutions containing traces of gallium and indium.
A distinctive feature of the present invention is that, in order to attain the stated object, gallium-containing jarosite is formed from a solution containing at least gallium, and the gallium is separated from other components and concentrated by dividing the jarosite into solid and liquid fractions.
Another distinctive feature of the present invention is that gallium-containing jarosite is formed from a solution containing at least gallium, and the gallium is separated from other components and concentrated by adding an alkali to the jarosite and leaching the material.
Yet another distinctive feature of the present invention is that gallium- and indium-containing jarosite is formed from a gallium- and indium-containing solution, and the gallium and indium are separated from other components and concentrated by dividing the jarosite into solid and liquid fractions.
Still another distinctive feature of the present invention is that gallium and indium are separated from other components and concentrated by means of the following steps:
a first step, in which one or more of iron(III) ions, sulfate ions, and monovalent cations are optionally added to a solution containing traces of gallium and indium to form a solution containing iron(III) ions, sulfate ions, and monovalent cations; and a mineral acid or an alkali reagent is optionally added to this solution to adjust the pH to 2-4;
a second step, in which the temperature of the solution obtained in the first step is raised to 70-100° C. under vigorous agitation, the system is allowed to react for 10 to 24 hours to give jarosite, and the gallium and indium are coprecipitated with jarosite particles; and
a third step, in which the reaction product obtained in the second step is divided into solid and liquid fractions, and the gallium- and indium-containing jarosite is recovered.
REFERENCES:
patent: 2574008 (1951-11-01), Beja
patent: 3684490 (1972-08-01), Steinviet
patent: 4071422 (1978-01-01), Charlton et al.
patent: 4986969 (1991-01-01), Tanihara
patent: A 59-193230 (1984-11-01), None
patent: WIPO 88/03912 (1988-06-01), None
Dutrizac, et al., “The Behavior of Impurities during jarosite precipitation,” Miner. Sci. Lab., CANMET Energy, Mines Resour. Canada, Ottawa, ON, NATO Conf. Ser., 6, 10(Hydrometall. Process Fundam.), pp. 125-169, 1984.*
Dutrizac, et al., “Behavior of indium during jarosite precipitation,” Publ. Australas. Inst. Min. Metall. 7/93(World Zinc '93), pp. 365-372, Oct. 1993.*
Dutrizac, et al., “The behavior of gallium during jarosite precipitation,” Can. Metall. Q., 39(1), pp. 1-14, Jan. 2000.
Kudo Yoshito
Maruyama Yukiko
Bos Steven
Dowa Mining Co. Ltd.
Oliff & Berridg,e PLC
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