Dissociation and solubility variation versus pO2- of scheelite CaWO4 in molten NaCl−KCl (At 1000 K) |
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| Authors: | R. Combes B. Tremillon F. De Andrade |
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| Affiliation: | Laboratoire d''Electrochimie Analytique et Appliquée (associé au C.N.R.S.), Ecole Nationale Supérieure de Chimie de Paris, Université Pierre et Marie Curie, 11 rue P. et M. Curie, F-75231-Paris Cedex 05 (France);Instituto da Quimica, Universidade Federal da Bahia, Salvador, Bahia (Brasil) |
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| Abstract: | The conditional solubility of scheelite CaWO4 in molten NaCl?KCl (1:1) has been studied either in oxobasic or oxoacidic media. In the former case it is increased by formation of sparingly soluble CaO according to:Ca2+ + O2CaO(s), pKsCaO = 10800/T ? 5.8 (molality scale) In the later case, WO42- behaves as an oxobase according to the following equilibria:WO42?WO3 (s) + O2? pK0 = 10.0 at 1000 K3 WO42?W3O102? pK3 = 12.7 at 1000KThe latter equilibrium favours an increase in the WVI solubility when pO2- is increased, for instance by injection of HCl. The whole set of results has been summarized by a conditional solubility diagram of scheelite versus pO2-. |
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| Keywords: | To whom all correspondence should be addressed. |
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