Recycling high purity indium from ITO wasted materials
The study was used to establish a method to recycle indium from ITO wasted solution and ITO wasted mud. The economical and efficient method was presented in the processes of hydrometallurgy and pyrometallurgy. In the hydrometallurgy method (chemical replacement), the powder of Mg and Zn were used to be the reducing agents. No matter in the ITO wasted solution or ITO wasted mud, the sponge indium was obtained by hydrometallurgy. In the pyrometallurgy method (slags making), the alkali compounds liked NaOH and KOH were used to make slags. The pure indium with a purity of 99.9% (3N) could be obtained from the sponge indium. The recycled indium was analyzed by Scanning Electron Microscopy, Energy Dispersive X-ray analysis, Inductively Coupled Plasma-mass spectrometry and Optical Microscope. In recycling indium from ITO wasted solution, the addition of Mg was 4.67g/L to replace the sponge indium and the operation temperature was room temperature. Moreover, the addition of NaOH was 6g/L to refine the sponge indium. The amount of pure indium was obtained 17.69g/L with a purity of 3N. In recycling indium from ITO wasted mud, the addition of Zn was 3g/L to replace the sponge indium and the operation temperature was 60℃. Besides the addition of KOH was 5.33g/L to refine the sponge indium. The amount of pure indium was obtained 5.39g/L with a purity of 99.7%. In this article, the recycling process involved electrochemical technology, vacuum smelting technology, thermodynamic theorems and microstructure analysis. Therefore, we detailed to study and discuss the behavior and characterization of indium by electrochemistry and thermodynamics.
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