Abstract: The invention relates to a method of manufacturing calcined aluminum fluoride, AlF.sub.3, from aluminum fluoride hydrate, especially aluminum fluoride trihydrate, AlF.sub.3.3H.sub.2 O, by drying and calcining. It is characterized in that(1) the hydrate is pre-dried or pre-calcined,(2) the pre-dried or pre-calcined hydrate is freed of the fine portion and(3) is totally dehydrated and calcined.The advantage of the method lies in the prevention of adhesions on the walls of the calcining apparatus, which restrict transmission of heat, which hitherto made continuous operation impossible, and in the increase of the purity of the product produced.A variation of method lies in the fact the fine component arising from the second method step is prepared into a coarser material, possibly added again to the product of the second method step which is free of fine component, and according to the third step of the method is dehydrated and calcined.

Abstract: The invention relates to a method of manufacturing calcined aluminum fluoride, AlF.sub.3, from aluminum fluoride hydrate, especially aluminum fluoride trihydrate, AlF.sub.3.3H.sub.2 O, by drying and calcining. It is characterized in that(1) the hydrate is pre-dried or pre-calcined,(2) the pre-dried or pre-calcined hydrate is freed of the fine portion and(3) is totally dehydrated and calcined.The advantage of the method lies in the prevention of the adhesions on the walls of the calcining apparatus, which restrict transmission of heat, which hitherto made continuous operation impossible, and in the increase of the purity of the product produced.A variation of method lies in the fact the fine component arising from the second method step is prepared into a coarser material, possibly added again to the product of the second method step which is free of fine component, and according to the third step of the method is dehydrated and calcined.

Abstract: The invention relates to a continuous, two-stage process for complete dehydration and subsequent calcination of aluminum fluoride hydrates.The known processes used for this purpose are satisfactory for producing relatively small quantities of aluminum fluoride. In the production of larger quantities of aluminum fluoride however several problems arise with respect to trouble free control and supervision of the process and maintainance of the equipment.The disadvantages which up to now have been mainly due to the process itself are removed by the combination of the following process steps:(a) Dehydrating the aluminum fluoride hydrate in a first step, to produce aluminum semi-hydrate AlF.sub.3.0.5H.sub.2 O by means of a generally known method(b) heating the aluminum semi-hydrate in a second stage in an indirectly heated, horizontal rotary kiln to remove the remaining water of crystallization, and then calcining at ca. 500.degree.-600.degree. C.

Abstract: A process for producing a compacted calcium fluoride based synthetic flux from an aqueous effluent containing fluorine ions, by precipitating fluorine ions as calcium fluoride, reducing the water content of the precipitate to the range from about 10 percent to 30 percent by weight, mixing the precipitate with a binding agent, compacting the mixture and thereafter drying the compacted mixture.