| 摘要 |
<p>Continuous synthesis of CaF2 from H2SiF6 comprises introducing 5-30 wt.% aq. H2SiF6 and 10-35, pref. 15-25 wt.% aq. CaCO3 suspension in a H2SiF6:CaCO3 molar ratio of 1:3 continuously and simultaneously into an intensive mixing zone and reacting 1-30. pref. 5-15 mins. at 5-40, pref. 15-25 degrees C and pH 2.0-4.0, pref. 3.0-3.5. The prod. is removed continuously and filtered after 5-40, pref. 15-30 mins., then the CaF2 is washed with water and dried. CaF2 with a low SiO2 and CaCO3 content is obtd. in an easily filtered form. In an example, CaF2 contg. 1.88 wt.% SiO2 and 0.25 wt.% CaCO3 was prepd.</p> |
