The concentration of the free fluoride ion was mathematically computed at which the solubility of
calcium fluoride would be exceeded with calcium concentrations known to be physiologic.
The viability of re-using the waste in this way depends not just on economic assessment but also on technical viability: whether impurities--primarily those, including arsenic, entering with HF catalyst--would build up in the process or whether they would leave with the
calcium fluoride. (6)
Though the residues of the decomposed chemical blowing agent are able to activate bubble formation, too, it could be proven for a concentration of 10 wt%
calcium fluoride particles that the nucleation behavior is enhanced probably because of the larger sized voids they create.
Using today's powerful tools, Burnett and his colleagues found intrinsic birefringence in
calcium fluoride. At 157 nm, Burnett says, the material exhibits 12 times the effect tolerable in current stepper designs.
For fluoride consumption by humans 3 mg F/day is a figure that should never be exceeded, and, of course, sodium fluoride in tooth pastes should be replaced with
calcium fluorides, which are much less toxic.
Fillers in these formulations can include copper, nickel, zinc, aluminum or non-metallic materials such as graphite,
calcium fluoride molybdenum disulfide, calcium hydroxide, zinc oxide or calcium oxide.
Commercial forms of sodium silico-fluoride contain 60 percent fluoride;
calcium fluoride, 47.7 percent; sodium fluoride, 40.5 percent to 44.1 percent; hydrofluosilicic acid, 23.7 percent; and ammonium fluosilicate, 64 percent.
Normally, only minute amounts of these elements are found on the earth's surface, but industry mines vast tonnages -- none in greater quantity than fluorine, which is most often found in the form of
calcium fluoride.
The secondary
calcium fluoride minerals gearksutite and creedite were reported from the mine by Jones (1980) and Besse (1981).
Del is planning No More Breaks, a restructuring nail strengthener with
calcium fluoride. Cosmair continues to support its successful Plenitude skin care line as it had promised to do, in addition to introducing a variety of color cosmetics.
Fluoridated saliva not only decreases critical pH, but also further inhibits demineralization of the deposited
Calcium fluoride at the tooth surface.
