[Fluoride emission from different soil minerals at high temperatures].
The emission characteristics of fluoride pollutants from montmorillonite, kaolinite, vermiculite, geothite and allophane were studied to elucidate the mechanism of fluoride-releasing from soils during brick and tile making at high temperatures from 300 degrees C to 1000 degrees C. The rate of fluoride emission varied with temperature, mineral type, heating time, specific surface area and cations added to minerals. The escape of crystalline water resulting from crystal lattice collapse at a certain high temperature was found to affect the rate of fluoride emission. Calcium compounds could decrease fluoride emission rate from montmorillonite. At 800 degrees C, the rate of fluoride emission from Ca-treated montmorillonite decreased by 59.6% compared to untreated montmorillonite. The order for fluoride-fixing capacity of the 5 calcium compounds at 800 degrees C was as follows: CaCO3 > CaO > Ca3(PO4)2 > Ca(OH)2 > CaSO4.
Wu
W
W
Institute of Soil and Water Resources and Environmental Science, Zhejiang University, Hangzhou 310029, China.
Xie
Z
Z
Xu
J
J
Liu
C
C
D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D005459:Fluorides / Q000032:analysis*; D006358:Hot Temperature; D007616:Kaolin / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
D000538:Aluminum Silicates; D008903:Minerals; D012989:Soil Pollutants; D001546:Bentonite; C003760:vermiculite; D007616:Kaolin; D005459:Fluorides