Improvements in method of producing alkali metal titanium double fluorides in which the titanium has a valence of less than four

摘要

Sodium, potassium or lithium titanium double fluorides in which the titanium has a valency less than four are prepared by heating a mixture of a sodium, potassium or lithium titanium double fluoride in which the titanium has a valency of four, carbon and a titanium oxide to 780-1150 DEG C. in an inert atmosphere. The reactants should be pure, and preferably the carbon and titanium oxide are thoroughly blended, pelletized using a binder such as methyl cellulose and water and dried at 150 DEG C. for 8-10 hours before mixing with the salt. Titanium monoxide, sesquioxide or dioxide may be used, and the carbon can be lamp-black or graphite. Suitable proportions are indicated and chemical reactions given. A temperature below 900 DEG C. favours the formation of trivalent titanium compounds and above 900 DEG C. divalent compounds are favoured. The reaction may be carried out in the presence of alkali metal (e.g. Na, K and Li) chlorides as diluents in up to equimolecular proportions with the initial fluotitanate. The reaction may be carried out in a furnace comprising a steel pot having a graphite resistance heating element in the form of a liner which supports a silicious insulating powder against the walls of the pot, a graphite reaction vessel disposed within said heating element and a gastight lid for said pot provided with electrical connections and the necessary pipes and valves for the supply and withdrawal of gases. After completion of the reaction the product may be filtered whilst still molten (this procedure is preferred in difluoride production) or cooled, crushed and leached with cold dilute hydrochloric acid. The mixture is filtered and a saturated solution of sodium fluoride added. After stirring and warming crystals are precipitated and recovered. The mother liquor is again treated with saturated sodium fluoride and a further crystalline precipitate is collected. Both batches of the product crystals may be dried at 105 DEG C., but they are not identical. The residue after leaching and the final liquor contain alkali metal-(tetravalent) titanium fluoride which may be recovered and re-used in the process. In one example in which filtration of the melt is employed it is stated that titanium oxycarbide is recovered on the filter. Specification 735,597 is referred to.