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Destroy HFCs and recover CaF2 with this process

By Tetsuo Satoh |

A process that destroys hydrofluorocarbons (HFCs) and recovers high-purity calcium fluoride has been developed by chemical-engineering professor Hideki Yamamoto at Kansai University (Suita City, Osaka; www.cheng.kansai-u.ac.jp/Process) in cooperation with Shiraishi Kogyo Kaisha Ltd. (Amagasaki City, Osaka; both Japan; www.shiraishi.co.jp/kogyo). The technology is based on calcium hydroxide, a byproduct from the process used to purify natural calcium carbonate. A mixture of Ca(OH)2 and HFCs is first decomposed at 500–550°C into CaF2, carbon-based residues, water and CO2 along with unreacted materials, such as CaO and CaCO3. The products are then heated to 700°C, which burns away the carbons, then dissolved in a mixture of HCl and HF acids. The HCl reacts with CaO and CaCO3 to form CaCl2, which then reacts with HF to form CaF2 — a sparingly soluble salt that precipitates. Yamamoto has recovered CaF2 with 95–98% purity using the method. A patent for the technology has been applied for, and the researchers are planning to demonstrate the process in compact reactors suitable for companies that manufacture HFCs as alternatives for chlorofluorocarbons (CFCs), as well as for treating CFCs.   Click here for…
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