Studies On The Recovery Of Gallium From Bayer Solution By Resin Sorption Method

Gallium is widely applied in solar energy,semiconductor,biology,chemical industry,alloy mobile phone devices,television and notebook displays,it accounts for 80-85%of the world's semiconductor application.The annual production in the world is only 200 tons,accounting for 8-21%of the development potential,so how to improve its production is the first concern.95%of the primary gallium originates from bauxite.In a view of Guangxi province's bauxite reserves rank second in China,extracting and recovering gallium from bauxite has become an indispensable research topic.However,there is no existing mine in the world dedicated solely to processing gallium.Gallium is often associated with aluminum,lead,germanium and other mines in ore deposits.Its content in bauxite is about 0.002-0.1%,which makes it difficult to extract.At present,gallium extraction is mainly carried out by resin adsorption method in industry.However,the resin method also has the problems of low adsorption capacity,slow mass transfer rate,and difficulty in regeneration.Therefore,new resin material should be used and gallium extraction technology need to be improved.In this paper,the commercial amidoxime resin LSC-600 was used to study the adsorption and separation performance of gallium in real Bayer liquor.The results indicate that the commercial amidoxime resin reaches equilibrium with the time of 100-120 min.The adsorption capacity is 2.3 mg g^-1.Vanadium ions will co-extracted indicates that there is a competitive adsorption.Increasing temperature has little effect on adsorption capacity.After saturation,hydrochloric acid was used for the desorption of loaded metal ions.Acid concentration and the temperature had the greatest effect on the desorption of gallium from the loaded resin.The separation effect on vanadium and gallium can be achieved at low hydrochloric acid concentration because competitive adsorption existed at a high concentration of the acid.The temperature has little effect on the elution of gallium and aluminum,comparing to vanadium.By using 1mol L^-1 hydrochloric acid,the elution rate of vanadium increased from20%to 95%by increasing temperature from 30?to 80?.Unfortunately,the coextraction of vanadium,the slow adsorption kinetic and low capacity of the commercial amidoxime groups are still the major issues during industrial operations.Consequently,further investigations are needed to solve these problems.A composite material?PAO/Si O₂??poly?amidoxime?silica composite?was synthesized by polymerization.The resin was characterized by XPS?X-ray photoelectron spectroscopy?,TGA?thermogravimetric analysis?,FTIR?Fourier-transform infrared spectroscopy?,p H_pzc,elemental analysis,and scanning electron microscopy coupled with energy dispersive x-ray analysis?SEM-EDS?.The sorption performance was investigated through the study of p H effect,sorption isotherms at different temperatures,and uptake kinetics under p H 4-5.5and at p H 13.7.From p H studies,the maximum sorption capacity reaches to2.1-2.6 mmol g^-1performed at optimum p H_eq close to 5.5.Uptake kinetics is relatively fast:under selected conditions,the equilibrium was reached within60–90 min;the kinetic profiles can be fitted by the pseudo-second-order rate equation and the resistance to intraparticle diffusion equation.The Langmuir equation gives a better mathematical adjustment in sorption isotherms.Metal desorption and resin recycling were performed using 1.5 M HCl.Desorption kinetics is fast:45 min was sufficient for achieving complete removal of Ga?III?.Sorption and desorption performances remain stable for a minimum of 5 cycles.Resin selectivity for gallium recovery was demonstrated in the presence of an excess of competitor metal cations.The resin was successfully applied for metal recovery from complex Bayer liquor at high p H values?around 14?:the resin is very efficient for gallium binding from complex solutions,with relatively high efficiency and selectivity compared with LSC-600 amidoxime resin.XPS spectra demonstrate that both O-and N-based reactive groups of amidoxime moieties are sharing electrons with Ga?III?after metal binding.In order to provide a higher purity gallium-enriched solution in the subsequent electrolysis process and reduce the interference of other ions,after desorption,at least three-step purification is needed to remove impurity before electrolysis.The purification process is complicated,and adding new chemical reagents increases the cost of recovering gallium.To solve these problems,Other complementary work,concern with Ga purification by using commercial anion resin IRA900 as the sorbent in the desorption solution,deionized water was used to elute gallium ion.The new trial was to replace the traditional process aiming to decrease the long process and save the purification process cost.The research indicated that the commercial resin IRA900 has a strong adsorption capacity with 220 mg g^-1 for gallium in 6mol L^-1 hydrochloric acid solution.However,the kinetic is slow:reaching adsorption equilibrium needs30 hours.Sorption and desorption performances remain stable for a minimum of5 cycles.The resin IRA900 was successfully applied for metal recovery from complex desorption solution which adjusted to 6mol L^-1 hydrochloric acid concentration:the resin is very efficient for gallium binding from complex solutions,with relatively high efficiency and selectivity towards gallium compared with vanadium,aluminum,magnesium,tungsten.A small amount of iron is adsorbed,but it's content is low which can be ignored.The elution column experiment using IRA900 resin suggesting that gallium is very easy to be eluted,the concentration after desorption can reach 6522 mg L^-1,and other elements are almost undetectable.Therefore,gallium could be easily desorbed with water and enriched without the interference by other ions through the new purification process.