Hydrogen fluoride mfr. from natural fluorspar - where solid reaction product is remilled and retreated to increase yield

摘要

The parent patent described the mfr. of HF by reaction of metal fluorides, esp. CaF2, with H2SO4, where all the reactants and carrier gases are heated above the b.pt. of the H2SO4, and the reaction carried out so no liq. phase condense, esp. H2SO4 or H2O. In the present invention, the novelty is that the natural fluorspar is milled to 150, esp. 60 mu m, before use; and the solid reaction prod. obtd. is retreated, possibly after remilling, with H2SO4 >340 degrees C, i.e. the process is repeated. The material passing through the reactor may be continuously milled, esp. using a ring roller crusher. The process can now be employed for all kinds of natural fluorspar, including those contg. carbonates, and yield of almost 100% obtd.