| 摘要 |
PURPOSE:To simultaneously obtain hydrogen fluoride and silicon tetrafluoride in high yield at a low cost by reacting inexpensive low-grade fluorite with concd. sulfuric acid under heating, circulating a generated gas contg. hydrogen fluoride and silicon tetrafluoride to the reaction system and continuing the reaction. CONSTITUTION:Fluorite contg. 1-30wt% silicic acid (expressed in terms of SiO2) is reacted with sulfuric acid having >=95wt% concn. at 100-300 deg.C. A generated gas contg. hydrogen fluoride and silicon tetrafluoride is circulated to the reaction system and the reaction is continued to simultaneously obtain hydrogen fluoride and silicon tetrafluoride. In order to circulate the gas, the gas generated in a reactor may be diverted from a pipe for drawing the gas and introduced again into the reactor. When plural reactors are arranged in series, the gas generated in the first reactor is introduced into the second reactor, where a similar reaction is carried out. Thus, hydrogen fluoride and silicon tetrafluoride can be simultaneously produced in high yield with inexpensive low-grade fluorite.
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