Title
The Reduction of Fluoride Dissolution During Induration Off-Gas Scrubbing
Other titles
The Reduction of Fluoride
Dissolution During Induration
Off-Gas Scrubbing: Final Report
Natural Resources Research Institute Technical Report
Publisher
University of Minnesota Duluth
Abstract
A research project supported by the Minnesota Department of Natural Resources and the
Iron Ore Cooperative Research Committee was undertaken to reduce the dissolution of
fluoride into process water during taconite processing. Leach tests were conducted
using rod mill feed samples and water containing varying concentrations of calcium and
sodium. Laboratory liberation grinds were performed to evaluate fluoride rejection
during grinding and magnetic separation. Tube furnace tests were conducted to evaluate
fluoride volatilization during pellet induration. The results indicate that fluoride
concentration of process water is a function of both calcium and sodium concentration in
process water. It appears that less than 1 percent of the fluoride present in rod mill feed
will dissolve in process water during grinding. More than 90 percent of the fluoride
present in rod mill feed is rejected with tailings during siz.e reduction and magnetic
separation. The furnace tests demonstrate that bentonite and fluxstone (calcite and
dolomite) addition to taconite concentrate during pellet production increases the amount
of fluoride that volatiliz.es during induration. Lime hydrate addition to pellets decreases
the amount of fluoride that volatilizes during pellet induration. During acid pellet
production approximately three times more fluoride enters the water during indurationoff-
gas scrubbing than during grinding. When fluxed pellets are produced three to eight
times more fluoride enters the water during off-gas scrubbing than during taconite
grinding.
Series/Report Number
NRRI Technical Report;
NRRI/TR-2001/18
CMRL Technical Report;
CMRL/TR-01-08
Description
Project #5600117; Final Report
Funding information
University of Minnesota - Duluth, Natural Resources Research Institute, 5013 Miller Trunk Highway, Duluth, Minnesota 55811; Coleraine Minerals Research Laboratory, P 0 Box 188, One Gayley Avenue, Coleraine, Minnesota 55722
Suggested Citation
Engesser, John.
(2001).
The Reduction of Fluoride Dissolution During Induration Off-Gas Scrubbing.
University of Minnesota Duluth.
Retrieved from the University of Minnesota Digital Conservancy,
https://hdl.handle.net/11299/188548.