The solubility of carbon dioxide has been measured by the thermogravimetric technique for CaO-CaF
2-SiO
2 molten fluxes at temperatures from 1 200 to 1 500°C. The values of carbonate capacity (
CC=wt%CO
32-/
PCO2) were calculated by the solubilities and the partial pressure of carbon dioxide.
Carbonate capacities were compared with the sulfide capacities appearing in the literature. A linear relationship was obtained for
CS2- and
CC as log
CS2-=1.1 log
CC -3.3 at 1 200 °C.
With increasing CaF
2 from 29.0 to 88.2wt% at constant
XCaO/
XSiO2 of three at 1 400°C,
CC increased from 0.53 to 0.89.
The influence of the replacement of CaO by CaF
2 on
CC at various SiO
2 content has been investigated. With increasing CaF
2,
CC decreased for fluxes of
XCaO/
XSiO2 smaller than three, while it increased for fluxes with a ratio larger than three.
Carbonate capacities of slags of
XCaO/
XCaF2=1.56 decreased with increasing SiO
2 content from 8.3 to 25wt%. In fluxes of which the ratio was 0.68,
CC decreased with an increase of SiO
2 more than 5wt%. There was a maximum of
CC at 0.8wt%SiO
2 for the fluxes of a ratio of 0.14.
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