| dc.description.abstract | With the advance of semi-conductor industry, a great amount of industrial waste material, such as scraped GaN-containing wafer, has been produced. Due to the shortage of Ga resources and the lack of ability to recycle Ga metal, the Ga recycling simulation had been developed in this study.
In this work, extractant-modified resin (D2EHPA/ XAD-4) had been used to recycle Ga ions in the ion exchanging process. The Chromatography module of Aspen Plus software was adopted in this research. The isothermal adsorption curve was fitted by extended Langmuir isotherm model while adsorption mass transfer resistance was modeled by Linear Lumped Resistance model. Due to the difference of operating method between isothermal adsorption experiments and ion exchange experiments which may affect the adsorption efficiency, the adsorption correction factor, fads, was estimated by the data of dynamics experiments in advance. The simulation of ion exchange experiments of pure Ga3+ solution, pure Al3+ solution, mixture of Ga3+ and Al3+ solution, and real waste dilute solution have been developed and fitted to the experimental data. The simulating program and parameters can be verified by the corresponding mass transfer coefficient and adsorption correction factor of the adsorption mentioned above. In order to obtain lower Al to Ga weight ratio and higher Ga recovery, several variables were discussed to find the best operating conditions. The finial operating conditions are adsorption step time 240 min, desorption step time 2010 min, adsorption flow rate 0.002 L/min, desorption flow rate 0.002 L/ min, bed diameter 1.6 cm, and height of resin layer 10 cm. The simulation results are 0.679% Al to Ga wt. ratio and 82.67% Ga recovery.
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