Title of Invention

"AN IMPROVED PROCESS FOR THE RECOVERY OF GALLIUM "

Abstract This invention relates to an improved process for the recovery of gallium which comprises soaking the chelating ion exchange resin such as herein described in pure 2 M NaOH solution for a period of 10-15 hours, decanting the supernatant alkali and packing the swollen resin in an ion exchange column, passing the gallium containing solution through the said column and eluting by known methods to recover gallium.
Full Text This invention relates to an improved process for the recovery of gallium using chelating ion exchange resins. Particularly, the present invention provides a method of gallium recovery by using a chelate ion exchange resin as described and claimed in our copending patent application No.601/Del/95 based on acrylic copolymers containing divinylbenzene as comonomer repeat unit having hydroxyamic acid group as the ligand in the acrylic moiety of the copolymer unit which when brought into contact with gallium containing solution facilitates the adsorption of gallium selectively on the resin followed by elution of the adsorbed gallium.
This method of invention is attractive with special reference to the extraction of gallium for which the demand is rapidly growing due to its increased use in electronic industries.This is further suitable to highly alkaline sodium aluminate liquor of the Bayer process of alumina production.
The chelating ion exchange resin is known to be useful in metal recovery
and is dependant upon the chelating ligand present in the resin. Among the
commercially known resins, resins with ligands like amidoxime
(Ref:Hydrometallurgy, 25, 1990,pp-1-18), carbamate (Ref: J.H. Hodgkin in
Encyclopaedia of polymer science and engineering, vol.3, p-367) have been
proved to be useful for uranium, mercury, cadmium, zinc, lead, copper and a
great variety of ligands based on sulphur are known for chelation of heavy metal
ions like mercury and lead. Commercially available resins having iminodiacetic
acid or oxime or amidoxime group as ligand though
suggested for gallium recovery, fail in
Selectivity, alkali and acid resistance, stability in repeated use. To overcome these difficulties, in a pending patent application no. 601/del/ 95, we have described and claimed a method of making a chelating ion exchange resin with hydroximic acid ligand attached to the acrylic - divinyl benzene copolymer for selective recovery of gallium.
The object of the present invention is to provide an improved process for the recovery of gallium using chelating ion exchange resin as described and claimed in our cop ending patent application no. 601/del/95.
Accordingly the present invention provides an improved process for the recovery of gallium which comprises soaking the chelating ion exchange resin such as herein described in pure 2 M NaOH solution for a period of 10-15 hours, decanting the supernatant alkali and packing the swollen resin in an ion exchange column, passing the gallium containing solution through the said column and eluting by known methods to recover gallium.
An embodiment of the present invention consists of evaluation of the resin in synthetic sodium gallate solution containing either gallium alone or in presence of aluminum or/and vanadium in varying concentration of alkaline solution.
The operation of the method due to the present invention involves adsorption of gallium onto the chelating ion exchange resin by bringing the gallium containing solutions as stated above in contact with the resin through a column method similar to the usual practice of ion exchange resin. Prior to the resin packing
in the ion exchange column, the resin is soaked in pure 2M NaOH solution for 12-15 hours and the swollen resin after decantation of supernatant alkali is packed in the ion exchange column. The ion exchange column used in this invention has 250 mm height with an inner diameter of 10 mm. The height of swollen resin is maintained as 80 mm . when following this column method, the gallium containing solution is passed by down flow down the column at a flow rate ranging from 50-200 ml/h and at room temperature of 30+_2° C . The test solution contains (i) gallium whose concentration ranges from 100-500 mg/1, (ii) gallium and 1 minimum, in which gallium concentration ranees from 100-300 mg/1 and aluminium concentration 40-60 g/l,and (iii) gallium, aluminium and vanadium in which the concentration of gallium and aluminium ranges as stated in (i) and (ii) while vanadium concentration ranges from 50- 150 mg/1, all in alkaline solution where the concentration of alkali as NaOH ranges from 120-300g/l. The effluent alkaline solution is analysed for its gallium content to compute gallium adsorption on the resin.
The stability of the resin in alkali/acid is evaluated by treating with alkali followed by acid after washing with water. The typical results are given in the table below . A known weight of the resin is treated with alkali under stirred condition using magnetic stirrer, washed and treated with acid of known strength under stirring condition. The resin is filtered, washed with water and dried in sunlight and weighed. The same resin is treated repeatedly.
Table; Stability of chelating resin towards alkali/acid treatment
Ut. of dry resin : 5 gms
Volume of alkali : 100 ml (2N NaOH)
Volume of acid : 100 ml (0.1N HC1)
MMA-DVB co-polymer with hydroxamic acid ligand
wt. of treated 5.0 5.0 4.9 5.0 4.9 4.9 4.8 4.8 4.8 4.8 resing
% loss 2 -- 2 2 4 4 4 4
For eluting the adsorbed gallium, the chelated resin on which gallium is adsorbed is washed with water and eluted with 200 ml of 10% HCl (v/v) at a flow rate of about 30 ml/h. The adsorption of gallium in the chelating ion exchange resin is further illustrated with the examples given below which however should not be construed to limit the scope of the invention.
Example 1
Volume of alkaline gal late = 100 ml
Initial gallium concentration = 200 mg/1
Alkali concentration as NaOH = 240 gm/1
Rate of flow = 100 ml/h
Volume of the resin bed = 8 ml
Final gallium concentration = 18 mg/I
% of gallium recovery = 91 %

Example 2
Volume of alkaline gal late Initial gallium concentration Alkali concentration as NaOH Rate of f1ow Volume of the resin bed Final gallium concentration % of gallium recovery

= 100 ml = 100 mg/1 = 80 gm/1 = 100 ml/h
= 8ml
= 13 mg/ 1
= 87 %


Example 3
Volume of synthetic sodium aluminate = 100 ml
Initial gallium concentration = 200 mg/
Alkali concentration as NaOH = 240 gm/
Aluminium concentration = 40 gm/I
Rate of flow = 100 ml/
Volume of resin bed = 8 ml
Final gallium concentration = 18 mg/1
% of gal Iium recovery = 91 %
Example 4
Volume of synthetic sodium aluminate = 100ml
Initial gallium concentration =200 mg/
Alkali concentration as NaOH = 240 gm/
Aluminium concentration = 60 gm/1
Rate of flow = 100 ml/
Volume of resin bed = 8 ml
Final gallium concentration = 28 mg/1
% of gallium recovery = 86 %
Example 5


Volume of synthetic sodium aluminate = 100 ml
Initial gallium concentration = 200 mg/l
Alkali concentration as NaOH = 240 gm/l
Aluminium concentration = 50 gm/l
Vanadium concentration = 100 mg/l
Rate of flow = 100ml/h
Volume of the resin bed = 8 ml
% of gallium recovery = 85%
The following are the advantages of the process operation described therein.
1. Ease of operation in adsorption/elution process.
2. Selective for lean gallate solutions.
3. Higher yield of gallium recovery.
4. Selectivity to the exclusive adsorption/elution of gallium.
5. Superior physical, chemical and mechanical stability leading to repeated use by regenerating them, thus enhancing the industrial value of the process of operation.




WE CLAIM
1. An improved process for the recovery of gallium which comprises soaking the chelating ion exchange resin such as herein described in pure 2 M NaOH solution for a period of 10-15 hours, decanting the supernatant alkali and packing the swollen resin in an ion exchange column, passing the gallium containing solution through the said column and eluting by known methods to recover gallium.
2. An improved process as claimed in claim 1 wherein the downfall flow of the gallium containing solution is maintained at a flow rate ranging from 50-200 ml/hr at room temperature.
3. An improved process as claimed in claim 1 to 2 wherein the elution is effected by washing the resin with 200 ml of 10% HCL (v/v) at a flow rate ranging from 20-40 ml/hr.
4. An improved process for the recovery of gallium
substantially as herein described with reference to the
examples 1 to 5.

Documents:

550-del-1995-abstract.pdf

550-del-1995-claims.pdf

550-del-1995-correspondence-others.pdf

550-del-1995-correspondence-po.pdf

550-del-1995-description (complete).pdf

550-del-1995-form-1.pdf

550-del-1995-form-2.pdf

550-del-1995-form-4.pdf

550-del-1995-form-6.pdf

550-del-1995-form-9.pdf


Patent Number 190737
Indian Patent Application Number 550/DEL/1995
PG Journal Number 33/2003
Publication Date 16-Aug-2003
Grant Date 15-Mar-2004
Date of Filing 27-Mar-1995
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI 110 001,INDIA
Inventors:
# Inventor's Name Inventor's Address
1 SWATI A.LAHIRI CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI, (INDIA
2 RAMANATHAN MEYYAPPAN CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI, (INDIA
3 SETHURAMAN PITCHUMANI CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI, (INDIA
4 ALAGAPPILLAI VARADMARAJ CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI, (INDIA
PCT International Classification Number C022B 58/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA