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US 4,460,551 AGranted
Process and device for manufacturing synthetic anhydrous calcium sulphate and pure hydrofluoric acid
AssigneeBuss AG
InventorsDieter Boese, Rene Etter
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AssigneeBuss AG
InventorsDieter Boese, Rene Etter
Estimating the term…
In the process for the production of synthetic anhydrite and pure hydrofluoric acid, a reaction is initiated using fluorspar with a mixture containing sulphuric acid, oleum and the reflux of the acidic scrubbing. The aim is to produce synthetic anhydrite which contains only the desired small proportion of CaF.sub.2, while the free H.sub.2 SO.sub.4 is completely neutralized, but other desirable accelerators are still retained. The reaction is so arranged that fluorosulphonic acid does not enter the reactor at all or only in minute quantity and the new formation of fluorosulphonic acid is effectively repressed. For this end, the components of CaF.sub.2 and acid mixture are fed into the reactor at an elevated temperature and the reactor intake is so heated, whereby the reaction is initiated at 100.degree. C. and thus new formation of fluorosulphonic acid is arrested. The exhaust gases from the reactor are hot-dried in a first stage and the dust is expelled, before the material is cooled in the subsequent stages.
In a process for the production of synthetic anhydrite and pure hydrofluoric acid in a reactor having at least two stages in which first reactor stage fluorspar and a hot acid mixture are admitted to initiate the reaction of calcium fluoride with sulfuric acid and produce gases including hydrogen fluoride gases followed by treating said gases in a scrubber with sulphuric acid to remove dust and water, said hot acid mixture comprising sulphuric acid, oleum and previously used scrubbing acid, that improvement consisting of reducing fluorine compounds from the scrubbing acid after it has been used for scrubbing by heating said scrubbing acid to a temperature from 100.degree. C. up to 200.degree. C. in a zone separate from contact with hydrogen fluoride containing process streams at normal pressure prior to addition of said scrubbing acid into the said acid mixture, the fluorine occurring in any form in the acid mixture of sulphuric acid, oleum and previously used scrubbing acid fed to the reactor corresponds at most to an amount of hydrogen fluoride of 1%.
Dependencies are inferred from the claim text.