Detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic.
A promising strategy for the detoxification and immobilization of chromite ore processing residue (COPR) in a spinel-based glass-ceramic matrix is reported in this study. In the search for a more chemically durable matrix for COPR, the most critical crystalline phase for Cr immobilization was found to be a spinel solid solution with a chemical composition of MgCr1.32Fe0.19Al0.49O4. Using Rietveld quantitative X-ray diffraction analysis, we identified this final product is with the phases of spinel (3.5wt.%), diopside (5.2wt.%), and some amorphous contents (91.2wt.%). The partitioning ratio of Cr reveals that about 77% of the Cr was incorporated into the more chemically durable spinel phase. The results of Cr K-edge X-ray absorption near-edge spectroscopy show that no Cr(VI) was observed after conversion of COPR into a glass-ceramic, which indicates successful detoxification of Cr(VI) into Cr(III) in the COPR-incorporated glass-ceramic. The leaching performances of Cr2O3and COPR-incorporated glass-ceramic were compared with a prolonged acid-leaching test, and the results demonstrate the superiority of the COPR-incorporated glass-ceramic matrix in the immobilization of Cr. The overall results suggest that the use of affordable additives has potential in more reliably immobilizing COPR with a spinel-based glass-ceramic for safer disposal of this hazardous waste.
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, PR China; Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, PR China.
Chang-Zhong
CZ
Liao
School of Environmental Science and Engineering, South University of Science and Technology of China, Shenzhen 518055, PR China.
Yuanyuan
Y
Tang
Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, PR China.
Po-Heng
PH
Lee
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550009, PR China. Electronic address: csliu@soil.gd.cn.
Chengshuai
C
Liu
Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, PR China. Electronic address: kshih@hku.hk.
Kaimin
K
Shih
Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650, PR China.
Fangbai
F
Li
Chromite ore processing residue (COPR); Detoxification; Glass-ceramic; Immobilization; Rietveld quantitative XRD