Role of Fe compounds in light aggregate formation from a reservoir sediment.
A one-step thermal process at 1050 degrees C and 1150 degrees C including bloating and sintering reactions produced lightweight aggregates (LWAs) with an apparent particle density of 2.08 and 1.18gcm(-3), respectively, from pellets made of the sediment of a local reservoir. The roles of Fe compounds occurred in the sediment in bloating mechanism were determined with X-ray absorption spectroscopy (XAS) technique. About 59at% of the total Fe is in forms of Fe(2+) in the raw sediment; whereas most Fe was oxidized to Fe(3+) in all LWAs, except in core part of the LWA produced at 1150 degrees C. The bloating reactions occurred in the core of the 1150 degrees C LWA is suggested to be mainly associated with the decomposition of FeSO(4) into FeO with a concomitant release of SO(2), SO(3), and O(2); the valence state of Fe was not changed. The generally accepted mechanism - the chemical reduction of Fe(2)O(3) component to FeO with a release of O(2) is responsible for the bloating phenomenon - is not observed in present study.
Wei
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YL
Department of Environmental Science and Engineering, Tunghai University, Taichung City 407, Taiwan. yulin@mail.thu.edu.tw
Lin
Y-Y
YY
D003247:Conservation of Natural Resources; D003252:Construction Materials; D005290:Ferric Compounds / Q000032:analysis* / Q000737:chemistry; D019015:Geologic Sediments; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D013696:Temperature; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis; D056928:X-Ray Absorption Spectroscopy
D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; D014867:Water; C000499:ferric oxide; D007501:Iron