Microstructural investigation on the mechanism to extract indium from wasted materials

Changes in the microstructure of indium oxide with the mechanochemical treatment have been examined using transmission electron microscopy. Grinding together with alumina powder produced fine particles of the indium oxide with a sub-nanometric size, and the effective surface area markedly increased. The increase of surface promoted the dissolution of indium from the sample soaked in acids, and therefore the yield of the precious element was much pronounced. On the basis of this microstructural change, some incomprehensible phenomena related to this process, e.g. abnormal decrease in diffraction intensity of the indium oxide in powder X-ray diffraction, could be explained reasonably.