Investigations on Indium and Zinc Leachabilities from Indium-Bearing Zinc Ferrite Improved by Planetary Ball Milling
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JMEPEG (2013) 22:1311–1318 DOI: 10.1007/s11665-012-0352-7
Investigations on Indium and Zinc Leachabilities from Indium-Bearing Zinc Ferrite Improved by Planetary Ball Milling J.H. Yao, X.H. Li, L.P. Pan, J.M. Mo, and Z.P. Wen (Submitted May 10, 2012; in revised form July 31, 2012; published online November 8, 2012) In this work, a high-energy planetary mill was used to modify the chemical stability of indium-bearing zinc ferrite (indium-bearing ZnFe2O4, IBZF) and improve indium and zinc leachabilities. The microstructures, morphologies, and leaching characteristics of IBZF samples milled under different milling conditions were investigated by particle size analysis, Brunauer-Emmett-Teller specific surface area analysis, x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, Mo¨ssbauer spectrometry, and leaching experiments. The results show that the planetary ball milling has obvious effects on the microstructure and leaching characteristic of IBZF. Increasing the rotation speed and milling time cause the increase in the specific surface area, structure defects, and the breakage of the crystalline network, which result in a significant increase of indium and zinc extractions. In particular, the changes of crystal lattice structure induced by planetary ball milling play a key role in improving indium and zinc leachabilities from IBZF. The planetary ball milling also results in the redistribution of Zn2+ and Fe3+ in IBZF.
Keywords
indium, leachability, planetary ball milling, zinc, zinc ferrite
1. Introduction Indium plays an important role in many fields such as electronics, nuclear field, thin-film coatings, and so on (Ref 1, 2). However, there are no independent indium deposits and indium is dispersed mostly in zinc deposits. Therefore indium is usually produced as a by-product of zinc metallurgy. During the roast process of zinc metallurgy, zinc ferrite (ZnFe2O4) can form easily when completely roasting at 950 C, meantime indium goes into zinc ferrite crystal lattice to form indium-bearing zinc ferrite (indium-bearing ZnFe2O4, IBZF) (Ref 3, 4). It is reported that the amount of zinc existed in the form of ZnFe2O4 is about 50% of the total zinc (Ref 5). Due to the stable structure of ZnFe2O4, the insoluble IBZF mainly exists in zinc leach residues during the leaching process of zinc metallurgy. Based on the above analysis, recovering indium and zinc from zinc leach residues belongs to economically important and technologically difficult task in view of the wide applications of indium and the stable chemical reactivity of IBZF contained in zinc leach residues. Generally, either drastic reaction conditions or a suitable preleach treatment has to be applied for the leaching J.H. Yao, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, PeopleÕs Republic of China, and College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004, PeopleÕs Republic of China; and X.H. Li, L.P. Pan, J.M. Mo, and Z.P. Wen, School of Chemistry and Chemical E
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