Experimental Study On Recovery Of Indium From ITO Etching Wastewater By Solvent Extraction

At present, the main field of application of indium is produce indium tin oxide thinfilm, which is used in the production of liquid crystal display. However, it will produce alot of etching wastewater in the process of production liquid crystal display. The etchingwastewater with a high acid level, and containing indium and tin, directly emission notonly cause great environmental pollution, but also waste the regenerative resources ofindium. In the case of indium resource shortage, recycling indium from the ITO etchingwastewater will be of great significance.The experimental recovery of indium from ITO etching wastewater by solventextraction was studied in the paper. Firstly, TBP was used to extract the etching wastewaterdirectly by the two grades of extraction in the optimal conditions, where the volumeconcentration of TBP was70%and the extracting time was5min and the phase ratio O/Awas1:1.5. The extraction efficiency of the indium could attain96.15%. Then using waterstripping TBP load organic phase, it realizes the stripping of indium and makes indium andtin to be separated successfully. The stripping efficiency of the indium could attain87.33%in the condition that the phase ratio O/A is3:1and the stripping time is4min. TheIndium-Enriched solution is finally gotten in enrichment of the stripping liquid. Theenrichment is achieved by using the extraction of P204and then it was stripping enrichedby HCl.The extraction efficiency of the indium could attain93.95%in the condition thatthe volume concentration of P204was30%and the phase ratio O/A was2:1and theextracting time was3min. In the stripping condition that the concentration of HCl was4mol/L and the phase ratio O/A is15:1and the stripping time is8min, the strippingefficiency of the indium could attain86.24%. When the Indium-Enriched solution pH wasregulated by NaOH to1~1.5and the temperature was controlled between50℃~60℃, theAluminum sheet was used as replacement. Finally sponge indium was recoveredsuccessfully.The purity of sponge indium was about90%.The replacement rate of indiumwas greater than99%.The study successfully recovered indium from ITO film etching wastewater. It achieved the utilization of indium from ITO film etching wastewater. The technology isfeasible and will have a good application prospect.