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Updated: Dec 27, 2025

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Microstructural analyses of Cr(VI) speciation in chromite ore processing residue from the soda ash process
Yaguang Du1, Maria Chrysochoou1
1Dept. of Civil and Environmental Engineering, Univ. of Connecticut, Storrs, CT, United States.
Abstract:
The microstructure of Chromite Ore Processing Residue (COPR) derived from the soda ash roasting process was investigated prior to and after removal of water exchangeable chromate using a host of microscopy and spectroscopy techniques. Soda ash COPR consists mostly of a magnesioferrite (MgFe2O4) matrix that has substantial substitution of trivalent chromium (Cr) for iron. The chromite particles are generally larger than the overall particle size distribution of COPR, containing most of the Cr mass in areas that are greater than 20 μm in diameter; chromite particles are also associated with most of the non-exchangeable hexavalent Cr (Cr(VI)), even though the binding mechanism is not well understood. The remaining non-exchangeable Cr(VI) was found in association with the surrounding Si- and Al-matrix, with spectroscopic evidence of the presence of Cr(VI)-hydrotalcite.
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