The present disclosure discloses a method for graded utilization of fluorine and silicon resources in a phosphate ore. While the phosphate ore reacts with sulfuric acid, a fluorine-containing and silicon-containing tail gas is produced. SiO.sub.2 and H.sub.2SiF.sub.6 solution with a high concentration are obtained by concentrating and filtering a solution containing HF and H.sub.2SiF.sub.6 formed after tail gas is absorbed by water. Crude SiF.sub.4 and a solution containing HF and H.sub.2SO.sub.4 are obtained by extracting, adsorbing, and dehydrating the H.sub.2SiF.sub.6 solution. SiF.sub.4 with a 5N purity is obtained after the crude SiF.sub.4 is adsorbed and distilled, at the same time, an impurity-enriched SiF.sub.4 is returned to operations of concentration and filtration to react with the solution containing HF and H.sub.2SiF.sub.6 to generate the H.sub.2SiF.sub.6 and SiO.sub.2. High-purity HF and waste sulfuric acid are obtained after the H.sub.2SO.sub.4 solution containing HF is separated by steam stripping and distillation.

This invention provides a method for stably producing 2,3,3,3-tetrafluoropropene for a long period of time wherein unreacted materials are reused after distillation without liquid-liquid separation to suppress catalyst deactivation. The method for producing 2,3,3,3-tetrafluoropropene comprises the step of reacting 1233xf or like chloropropene with hydrogen fluoride in the presence of a catalyst, the step of subjecting the reaction mixture obtained in the above step to distillation to separate the mixture into a first stream comprising 2,3,3,3-tetrafluoropropene as a main component and a second stream comprising unreacted hydrogen fluoride and organic matter containing unreacted chloropropene as main components, and the step of recycling the second stream to the above reaction, the distillation being performed under conditions in which the unreacted hydrogen fluoride and the organic matter containing the unreacted chloropropene do not undergo liquid-liquid separation at a portion of a distillation column from which the second stream is withdrawn.

An azeotropic or quasi-azeotropic composition including hydrogen fluoride, 1,3,3,3-tetrafluoropropene and one or more (hydro)halogen-carbon compounds including between 1 and 3 carbon atoms. Also, a preferred azeotropic or quasi-azeotropic composition comprising hydrogen fluoride, 1,3,3,3-tetrafluoropropene, and one or more compounds selected from among 1,1,1,2,2-pentafluoropropane, 2,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, 3,3,3-trifluoro-2-chloropropene, E-3,3,3-trifluoro-1-chloropropene, trifluoropropyne, 1,1,1,3,3-pentafluoropropane, 1,1,3,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropene, 1,1,1,2,3-pentafluoropropene and 2-chloro, 1,1,1,2-tetrafluoropropane.

This disclosure describes systems and methods for removing uranium hexafluoride (UF.sub.6) and/or other uranium fluoride (uranium fluorides identified herein generally as UF.sub.x) gases from a hydrogen fluoride (HF) gas stream.

A method for preparing electronic grade inorganic acids includes: introducing alkali metal salts into a waste acid solution containing hydrofluoric acid, nitric acid and water to obtain hydrogen fluoride vapor, and a distillation residue mixture containing nitric acid, water and the alkali metal salts; subjecting the first distillation residue mixture to evaporation treatment, and then introducing an alkali earth metal nitrate salt into the resultant nitric acid/water mixture followed by distillation treatment so as to obtain nitric acid vapor; and removing mist droplets in the hydrogen fluoride and nitric acid vapor, followed by condensation treatment and concentration adjustment so as to obtain electronic grade hydrofluoric acid and nitric acid.

A fluoride ion cleaning system includes a retort for cleaning at least one component via a working fluid supplied to the retort, a post-retort subsystem for processing a post-retort fluid stream exiting the retort at a first temperature, and a scrubber downstream from the post-retort subsystem. The post-retort subsystem includes a separator in flow communication with the retort. The separator includes an inlet for receiving the post-retort fluid stream from the retort and an outlet for the post-retort fluid stream exiting the separator. The post-retort subsystem also includes a cooling device for selectively cooling the post-retort fluid stream to a second temperature, the second temperature being lower than the first temperature. The second temperature enables particulate to be separated from the post-retort fluid stream within the separator.