Preparation of hydrogen fluoride from calcium fluoride and sulfuric acid
AssigneeSolvay Fluor GmbH
InventorHelmut Grass
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Abstract
Calcium fluoride fines or residues comprising calcium fluoride fines, e.g. residues from treating waste water or waste gas, e.g. originating from HF or fertilizer production, with calcium oxide or calcium carbonate to remove HF or fluorides can be converted to HF and calcium sulfate by reaction with sulfuric acid in the form of a suspension. Unreacted calcium oxide or calcium carbonate generates sufficient heat to the endothermic reaction between calcium fluoride and sulfuric acid so that no external heat is needed.
Claims20
A process for the preparation of HF and calcium sulfate wherein essentially dry calcium fluoride is reacted in the form of a suspension with essentially water free sulfuric acid, wherein the solids content in the suspension is equal to or lower than 25% by weight.
The process according to claim 18 wherein the starting material is a residue from waste water purification or waste gas purification to remove HF.
Dependencies are inferred from the claim text.