CA1042628A - Recovery of gallium oxide from solutions - Google Patents
Recovery of gallium oxide from solutionsInfo
- Publication number
- CA1042628A CA1042628A CA216,509A CA216509A CA1042628A CA 1042628 A CA1042628 A CA 1042628A CA 216509 A CA216509 A CA 216509A CA 1042628 A CA1042628 A CA 1042628A
- Authority
- CA
- Canada
- Prior art keywords
- solution
- gallium
- gallium oxide
- alumina
- precipitation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
ABSTRACT
Process for recovery of gallium from alkali metal aluminate solutions by co-precipitation of alumina and gallium oxide, followed by circulation of the co-precipitate in the solution for an extended period to effect precipitation of further gallium oxide.
This invention relates to recovery of gallium oxide from alkali metal aluminate solutions which contain dissolved gallium.
Process for recovery of gallium from alkali metal aluminate solutions by co-precipitation of alumina and gallium oxide, followed by circulation of the co-precipitate in the solution for an extended period to effect precipitation of further gallium oxide.
This invention relates to recovery of gallium oxide from alkali metal aluminate solutions which contain dissolved gallium.
Description
Prior Art It is known that sodium aluminate solutions con-taining a low concentration of desired gallium are proauced in the well known Bayer process for the production of alumina hydrate by repeated cycles of digesting bauxite in hot caustic soda solution, followed by precipitation of alumina hydrate by "feeding" the solution with previously precipitated alumina hydrate and recycling the solution to digest additional bauxite. Some of the gallium values present in the bauxite are dissolved, and the concentration of gallium in the solutior gradually increases during repeated digests of bauxite in the solution, until an equ_librium is reached, usually at about 0.1 - 0.2 gramsper liter, depending upon the gallium content of the bauxite. It is also known that sodium aluminate solutions containing a relatively low concentration of dissolved gallium can be produced by dissolving in a caustic soda solution gallium-containing anode metal produced in the well known 3-layer electrolytic process for the purification of aluminum.
U.S. Patents 2,574,008 and 2,582,376 describe recovering gallium oxide from such gallium-containing solutions by first decreasing the ratio of dissolved alumina to gallium in the solution, and thereafter co-precipitating 1~)4Z628 alumina and gallium oxide from the solution by addition of an acid, such as, carbon dioxide, though other acidic materials can be used. However, as the concentration of gallium in the solution becomes progressively lower in the course of such co-precipitation of alumina and gallium oxide, precipitation of additional gallium oxide becomes increasingly difficult and expensive, and eventually becomes uneconomical prior to precipitation of all of the gallium values present in the solution. As a result, a procedure for increasing the economically recoverable proportibn of the gallium values is desirable.
THE INVENTION
It is an object of the invention to provide an improved procedure for recovering gallium oxide from alkali metal aluminate solutions containing a low concentration of dissolved gallium, and it is a particular object of the invention to increase the proportion of dissolved gallium values recoverable economically from sodium aluminate solutions from which gallium oxide is precipitated by feeding acid into the solution.
It has been found that after part of the gallium present in an alkali metal aluminate solution containing dissolved gallium has been precipitated from the solution as a co-precipitate of alumina and gallium oxide, additional gallium oxide can be precipitated from the solution by circulating the co-precipitated alumina and gallium oxide through the solution for an extended time. Thus, in accordance with this invention, alumina and gallium oxide are co-precipitated from an alkali metal aluminate solution containing dissolved gallium by adding an acid-preferably carbon dioxide or carbonic acid solution-to the solution and thereby precipitating part of the dissolved gallium values from the solution, after which the solution is agitated ~-i 1~4Z628 sufficiently to keep the co-precipitate circulating through it until the desired further precipitation of gallium oxide has been effected.
By circulating the co-precipitated alumina ~
and gallium oxide in the solution for sufficient time, substantially all of the dissolved gallium present in the solution at the outset can be recovered, if desired.
Prior to the abovementioned step of co-precipitating alumina and gallium oxide by add~tion of acid to the solution, the ratio of alumina to gallium in the solution may be reduced by precipitating alumina from the solution by procedures disclosed in Patents 2,574,008 and 2,582,376.
Circulation of the co-precipitate of alumina and gallium oxide in the solution to precipitate additional gallium oxide as described above can be effected by agitation of the solution rapidly by well known stirring devices.
The duration of circulation of the co-precipitate in the solution for the above purpose depends to some extent on such variables as the concentration of gallium in the solution, the ratio of circulated alumina-gallium oxide co-precipitate to dissolve gallium present, the proportion of the initial dissolved gallium to be recovered by circulation of the co-precipitated alumina and gallium oxide in the solution, and the rate at which the co-pre-cipitate is circulated within the solution. However, precipitation of gallium oxide by circulation of the previously co-precipitated alumina and gallium oxide through the solution proceeds relatively slowly, and it has been found that circulation of the co-precipitate for a period of at least 15 hours is generally desirable, and a period o at least 30 hours is preferred. Following precipitation - 16)42628 of the desired amount of additional gallium oxide by the procedures described above, the precipitated solids can be separated from the residual solution, as by decantation, sedimentation, or filtration.
As mentioned above~ co-precipitation of alumina and gallium oxide from the gallium-containing sodium aluminate solution can be effected'by introducing an acid into the solution. The rate and amount of acid introduced for best resul~ will vary depending on such factors as the particular acid used, and the proportion of the dissolved gallium values which it is economical to precipitate in that manner. It is generally advantageous to feed the acid into the solution rapidly.
The following examples illustrate the practice of the invention and increased recovery of gallium oxide.
'~xample l Carbon dioxide was fed into a solution containing 4.1 grams per liter of alumina, ll.0 grams per'liter total caustic, and 0.152 grams per liter of dissolved gallium for
U.S. Patents 2,574,008 and 2,582,376 describe recovering gallium oxide from such gallium-containing solutions by first decreasing the ratio of dissolved alumina to gallium in the solution, and thereafter co-precipitating 1~)4Z628 alumina and gallium oxide from the solution by addition of an acid, such as, carbon dioxide, though other acidic materials can be used. However, as the concentration of gallium in the solution becomes progressively lower in the course of such co-precipitation of alumina and gallium oxide, precipitation of additional gallium oxide becomes increasingly difficult and expensive, and eventually becomes uneconomical prior to precipitation of all of the gallium values present in the solution. As a result, a procedure for increasing the economically recoverable proportibn of the gallium values is desirable.
THE INVENTION
It is an object of the invention to provide an improved procedure for recovering gallium oxide from alkali metal aluminate solutions containing a low concentration of dissolved gallium, and it is a particular object of the invention to increase the proportion of dissolved gallium values recoverable economically from sodium aluminate solutions from which gallium oxide is precipitated by feeding acid into the solution.
It has been found that after part of the gallium present in an alkali metal aluminate solution containing dissolved gallium has been precipitated from the solution as a co-precipitate of alumina and gallium oxide, additional gallium oxide can be precipitated from the solution by circulating the co-precipitated alumina and gallium oxide through the solution for an extended time. Thus, in accordance with this invention, alumina and gallium oxide are co-precipitated from an alkali metal aluminate solution containing dissolved gallium by adding an acid-preferably carbon dioxide or carbonic acid solution-to the solution and thereby precipitating part of the dissolved gallium values from the solution, after which the solution is agitated ~-i 1~4Z628 sufficiently to keep the co-precipitate circulating through it until the desired further precipitation of gallium oxide has been effected.
By circulating the co-precipitated alumina ~
and gallium oxide in the solution for sufficient time, substantially all of the dissolved gallium present in the solution at the outset can be recovered, if desired.
Prior to the abovementioned step of co-precipitating alumina and gallium oxide by add~tion of acid to the solution, the ratio of alumina to gallium in the solution may be reduced by precipitating alumina from the solution by procedures disclosed in Patents 2,574,008 and 2,582,376.
Circulation of the co-precipitate of alumina and gallium oxide in the solution to precipitate additional gallium oxide as described above can be effected by agitation of the solution rapidly by well known stirring devices.
The duration of circulation of the co-precipitate in the solution for the above purpose depends to some extent on such variables as the concentration of gallium in the solution, the ratio of circulated alumina-gallium oxide co-precipitate to dissolve gallium present, the proportion of the initial dissolved gallium to be recovered by circulation of the co-precipitated alumina and gallium oxide in the solution, and the rate at which the co-pre-cipitate is circulated within the solution. However, precipitation of gallium oxide by circulation of the previously co-precipitated alumina and gallium oxide through the solution proceeds relatively slowly, and it has been found that circulation of the co-precipitate for a period of at least 15 hours is generally desirable, and a period o at least 30 hours is preferred. Following precipitation - 16)42628 of the desired amount of additional gallium oxide by the procedures described above, the precipitated solids can be separated from the residual solution, as by decantation, sedimentation, or filtration.
As mentioned above~ co-precipitation of alumina and gallium oxide from the gallium-containing sodium aluminate solution can be effected'by introducing an acid into the solution. The rate and amount of acid introduced for best resul~ will vary depending on such factors as the particular acid used, and the proportion of the dissolved gallium values which it is economical to precipitate in that manner. It is generally advantageous to feed the acid into the solution rapidly.
The following examples illustrate the practice of the invention and increased recovery of gallium oxide.
'~xample l Carbon dioxide was fed into a solution containing 4.1 grams per liter of alumina, ll.0 grams per'liter total caustic, and 0.152 grams per liter of dissolved gallium for
2 hours, thereby producing 91.4 grams per liter of sodium bicarbonate in the solution and co-precipitating sufficient alumi'na and gallium oxide that the solution contained essentially no dissolved alumina, and 0.110 grams per liter of dissolved gallium. Thereafter, the co-precipitated'alumina and gallium oxide were kept suspended in the solution and circulated fluid for 72 hours by agitation of the solution and the precipitate, but without adding further carbon dioxide. At the end of 24 hours sufficient additional gallium oxide had been precipitated that the solution contained 0.04 grams per liter of dissolved gallium. At the end of 72 hours the solution contained only 0.014 grams per liter o dissolved gallium. 4 1~42628 Example 2 Carbon dioxide was bubbled through a sodium aluminate solution of the composition described in Example 1 for 2 hours, co-precipitating enough alumina and gallium oxide that the resultant solution contain 0.006 grams per liter of alumina, 0.096 grams per liter of gallium, and 95.4 grams per liter of sodium bicarbonate.
The co-precipitation was filtered immediately from the solution, after which the solution was stirred for 64 hours at 54C. At the end of that time, no additional alumina or gallium values had precipitated from the solution.
The abovementioned co-precipitated alumina and gallium oxide which had been removed from the solution was then returned to the solution and the mixture was stirred for 96 hours at 54C. at the same rate as before, thereby keeping the co-precipitate suspended in the solution.
At the end of 24 hours the solution contained 0.035 grams per liter of dissolved gallium; at the end of 96 hours it contained only 0.017 grams per liter of dissolved gallium.
The co-precipitation was filtered immediately from the solution, after which the solution was stirred for 64 hours at 54C. At the end of that time, no additional alumina or gallium values had precipitated from the solution.
The abovementioned co-precipitated alumina and gallium oxide which had been removed from the solution was then returned to the solution and the mixture was stirred for 96 hours at 54C. at the same rate as before, thereby keeping the co-precipitate suspended in the solution.
At the end of 24 hours the solution contained 0.035 grams per liter of dissolved gallium; at the end of 96 hours it contained only 0.017 grams per liter of dissolved gallium.
Claims (2)
1. In the process of recovering gallium oxide from an alkali metal aluminate solution containing dissolved gal-lium, which comprises co-precipitating alumina and part of the gallium oxide by introducing into the solution an acid capable of effecting such co-precipitation, the improvement comprising circulating the co-precipitated alumina and gal-lium oxide through the solution for a period of at least 15 hours, the solution parameters being maintained in a mode conducive to the precipitation of gallium oxide, whereby ad-ditional gallium oxide is precipitated from the solution.
2. A process in accordance with claim 1 in which the said period is at least 30 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA216,509A CA1042628A (en) | 1974-12-20 | 1974-12-20 | Recovery of gallium oxide from solutions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA216,509A CA1042628A (en) | 1974-12-20 | 1974-12-20 | Recovery of gallium oxide from solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042628A true CA1042628A (en) | 1978-11-21 |
Family
ID=4101907
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA216,509A Expired CA1042628A (en) | 1974-12-20 | 1974-12-20 | Recovery of gallium oxide from solutions |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1042628A (en) |
-
1974
- 1974-12-20 CA CA216,509A patent/CA1042628A/en not_active Expired
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