Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group va metal or arsenic
Patent
1989-07-19
1991-05-28
Andrews, Melvyn J.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group va metal or arsenic
423 98, 423112, C22B 338
Patent
active
050193635
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the recovery of indium and possible related elements contained in a solution of chlorides of indium and various other elements and particularly tin chloride and antimony chloride; it particularly relates to the separation of tin and antimony from indium.
The development of novel applications for indium, among which may be mentioned the compounds III-V, conductive transparent films used in displays and in photovoltaics and the mixed indium-tin oxides which allow the greenhouse effect to be trebled, has made the recovery of this element particularly attractive, it often being found associated with ores of the common non-ferrous metals, particularly blend, chalcopyrite and galena.
The recovery from a sulphate solution has already been the subject of numerous studies and patents, particularly the French Patent Application published under the number 2,435,533.
It happens that in the course of pyrometallurgical processes indium accumulates in various phases which may readily be subjected to chlorinated dissolution, with or without oxidation, to give a solution of indium chloride. Certain solutions of metallic chloride, such as those which are produced by the process described in the French Patent 2,317,366, may contain indium which it may be opportune to recover.
The separation of indium from tin and antimony, elements to which it is chemically similar, is known technically but the solutions which have been proposed are not satisfactory and are expensive to use. In particular, extractions have been proposed using organic compounds of the ether type or of the ketone type; more particularly, numerous studies have been based on methyl isobutyl ketone.
However, all these products are volatile and present fire risks and explosion risks which are not negligible.
For this reason one of the objects of the present invention is to provide a process for the hydrometallurgical treatment of a solution of indium chloride, which may be mixed with tin chloride or antimony chloride, which uses an extractant which should not be inflammable or explosive.
Another object of the present invention is a process which allows a good separation of indium chloride from antimony chloride and that of tin.
These objects, and others which will appear subsequently, are achieved by means of a process for the hydrometallurgical treatment of a solution of indium chloride and at least one element selected from the group comprising tin and antimony, characterized in that it comprises the following steps:
a) adjustment of the concentration of free chloride ion by addition of a chloride of an alkali metal or a chloride of an alkaline earth metal or a mixture of these and adjustment of their acidity by addition of hydrochloric acid;
b) bringing the said solution of indium chloride into contact with an organic phase comprising trialkyl phosphate;
c) reextraction of the said organic phase by bringing the latter into contact with a solution of 0.1 to 3N hydrochloric acid, to obtain a solution of indium chloride;
d) basic reextraction using an alkali metal hydroxide.
The adjustment of the concentration of chloride ion and acidity is important because it is desirable to extract essentially all the refinable elements and because the concentration of chloride ion and the acidity have a very great influence on achieving this recovery using trialkyl phosphate Preferably, the concentration of free chloride ion is adjusted to a value in the range 3 to 12N and the acidity to a value in the range 1 to 6N. This adjustment is preferably made using calcium chloride; a particularly advantageous range is a solution of indium chloride which contains in addition 5 to 10N chloride ions preferably in the form of calcium chloride and 1 to 3N acidity. Generally the conditions are within the median values of these brackets.
"Free chloride ion" is understood to mean chloride ions which are not associated with an element whose extraction is desired, using trialkyl phosphate, in the form of an uncharged complex (for example InCl.sub.3, HInCl.sub.4
REFERENCES:
patent: 3180812 (1965-04-01), Beau
patent: 4292284 (1981-09-01), Tomii et al.
patent: 4372922 (1983-02-01), Fossi et al.
patent: 4525333 (1985-06-01), Schimmel et al.
Fossi Paolo
Le Quesne Yves
Andrews Melvyn J.
Metaleurop S.A.
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