Thermodynamics of the conversion of calcium and magnesium fluorides to the parent metal oxides and hydrogen fluoride

Technical Report · Sat Feb 01 04:00:00 EST 1997

DOI:https://doi.org/10.2172/468512· OSTI ID:468512

West, M H; Axler, K M

The authors have used thermodynamic modeling to examine the reaction of calcium fluoride (CaF{sub 2}) and magnesium fluoride (MgF{sub 2}) with water (H{sub 2}O) at elevated temperatures. The calculated, equilibrium composition corresponds to the global free-energy minimum for the system. Optimum, predicted reaction temperatures and reactant mole ratios are reported for the recovery of hydrogen fluoride (HF), a valuable industrial feedstock. Complete conversion of MgF{sub 2} is found at 1,000 C and a ratio of 40 moles of H{sub 2}O per 1 mole of MgF{sub 2}. For CaF{sub 2}, temperatures as high as 1,400 C are required for complete conversion at a corresponding mole ratio of 40 moles of H{sub 2}O per 1 mole of CaF{sub 2}. The authors discuss the presence of minor chemical constituents as well as the stability of various potential container materials for the pyrohydrolysis reactions at elevated temperatures. CaF{sub 2} and MgF{sub 2} slags are available as wastes at former uranium production facilities within the Department of Energy Complex and other facilities regulated by the Nuclear Regulatory Commission. Recovery of HF from these wastes is an example of environmental remediation at such facilities.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 468512
• Report Number(s): LA--13232-MS; ON: DE97004819
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
CALCIUM FLUORIDES
HYDROFLUORIC ACID
HYDROLYSIS
MAGNESIUM FLUORIDES
MATERIALS RECOVERY
MATHEMATICAL MODELS
RADIOACTIVE WASTE PROCESSING
THEORETICAL DATA
THERMODYNAMICS