METHOD FOR RECOVERING CALCIUM FLUORIDE

PROBLEM TO BE SOLVED: To recover high-purity calcium fluoride from a calcium mixture. SOLUTION: In the method, the calcium fluoride is recovered from the calcium mixture including calcium fluoride and at least one selected from calcium oxide and calcium carbonate. The method comprises: a first separ...

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Hauptverfasser:	NAKAYAMA NORIHIKO, MATSUBARA KATSURA, YAMAMOTO HIDEKI
Format:	Patent
Sprache:	eng
Schlagworte:	CHEMISTRY COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM,CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THERARE-EARTH METALS DISPOSAL OF SOLID WASTE INORGANIC CHEMISTRY METALLURGY PERFORMING OPERATIONS RECLAMATION OF CONTAMINED SOIL SOIL TRANSPORTING
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Beschreibung
Zusammenfassung:	PROBLEM TO BE SOLVED: To recover high-purity calcium fluoride from a calcium mixture. SOLUTION: In the method, the calcium fluoride is recovered from the calcium mixture including calcium fluoride and at least one selected from calcium oxide and calcium carbonate. The method comprises: a first separation stage where acid (HA) is added to the calcium mixture, and, by reaction based on formula (F1) and formula (F2), an acid-derived calcium compound (CaA) and water are produced, and further, the calcium fluoride not reacted with the acid (HA) is separated; and a second separation stage where hydrogen fluoride is added to the acid-derived calcium compound (CaA) produced in the first separation stage, and the calcium fluoride produced based on formula (F3) is separated. The formula (F1) is CaO+2HA→CaA+H2O, the formula (F2) is CaCO3+2HA→CaA+H2O+CO2, and the formula (F3) is 2CaA+2HF→CaF2+2HA. COPYRIGHT: (C)2010,JPO&INPIT