GB792023A - Improvements in process for producing sodium fluoride from an alkaline earth fluoride - Google Patents

Abstract

An alkaline earth metal fluoride is reacted with one or more of potassium aluminate, silicate and ferrite at a temperature at which the mixture is molten and the melt is quenched in sufficient water to dissolve most of the melt comprising potassium fluoride, but insufficient to dissolve the alkaline earth metal compound; the solution is separated and reacted with a sodium compound to obtain sodium fluoride. Specified alkaline earth metals are calcium, magnesium, barium and strontium; the potassium silicate, aluminate and ferrite may be obtained by fusion of the appropriate oxide with potassium carbonate at 850 DEG , 975 DEG and 1150 DEG C. respectively; potassium chloride may be included in the silica melt; and the sodium compound reacted with the potassium fluoride may be sodium hydroxide, silicate or carbonate. In the latter case, the temperature may be near the boiling point or at room temperature and the resultant by-product potassium carbonate together with any excess potassium silicate &c. may have an equimolecular proportion of the appropriate oxide added thereto and then be evaporated to dryness to form potassium silicate &c. for re-use. It is stated that calcium silicate produced in the process is in the form of a fine powder and may be used as a filler or pigment, if desired after dissolving in hydrochloric acid, filtering and evaporating. Specification 19738/08, [Class 1], is referred to.