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Fluorination of Sulphide Minerals with Ammonium Bifluoride by N.M. Laptash; S.A. Polyshchuk; T.A. Kalacheva; E.I. Melnichenko is a Chemistry article available to read on EtoBox.

What is Fluorination of Sulphide Minerals with Ammonium Bifluoride about?

Ammonium bifluoride is known to be an important reagent for the processing of minerals. Despite this importance of NH\*HF, surprisingly little is known about its interaction with metal sulphides. Pyrrhotine Fe1 \_,S is a non-stoichiometric iron compound with a defective structure in which the metal atom has a mixed valence (Fe'+ and Fe3+). It is that particularity of pyrrhotine that influences its interaction with NH,HF,. Ammonium iron fluorocomplexes (NH,),FeF& (2 G x G 3) with a cryolite structure were obtained in the temperature region 200-250 "C. Here x depends on the Fe'+ : Fe3+ ratio. These complexes are stable up to 300 "C; they are then decomposed, with a FeF, and FeF, mixture formed in quasi static conditions. Pyrrhotine fluorination is accompanied by elementary sulphur formation. By further heating, sulphur forms the volatile oxyfluoride SOaF,, which may be condensed with NH3 and HF gases at 250-300 "C to produce ammonium fluorosulphate. It was interesting to find that the stoichiometric metal sulphides such as ZnS, PbS, Fe&, CuFeS,, FeAsS do not interact with NH4HF2.

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Author

N.M. Laptash; S.A. Polyshchuk; T.A. Kalacheva; E.I. Melnichenko

Publisher

Elsevier Science; Elsevier ; Elsevier BV (ISSN 0022-1139)

Published

1992

Language

EN

Field

Chemistry (Physical Sciences)