The invention relates to a method for treating fluoride-containing, in particular HF containing wastewater to remove fluoride and to a corresponding apparatus. In the new method calcium carbonate is reacted in a reaction step at an acidic pH≤4 with the fluoride in the wastewater to form calcium fluoride particles. Then, in a subsequent filtration step said calcium fluoride particles are separated by a porous membrane from the treated wastewater. The inventive apparatus comprises at least one reaction container/tank for reacting calcium carbonate at an acidic pH≤4 with fluoride in the wastewater to form calcium fluoride particles, as well as at least one porous membrane, in particular at least one porous ceramic membrane for separating calcium fluoride particles from the treated wastewater in a filtration step.

A technique for obtaining anhydrous hydrogen fluoride (AHF) from an aqueous solution of hexafluorosilicic acid (HSA). A method for obtaining hydrogen fluoride from an aqueous solution of hexafluorosilicic acid can include mixing a solution of hexafluorosilicic acid with a sulfuric acid solution, desorbing the hydrogen fluoride from the resultant solution of sulfuric acid, treating it with sulfuric acid and condensing the anhydrous hydrogen fluoride from unabsorbed gasses. The generated gaseous products are then burned in a fire of hydrogen-containing fuel and an oxygen-containing oxidant, yielding a solid silicon dioxide. The remaining products are cooled and yield condensed anhydrous hydrogen fluoride.

Extraction of anhydrous hydrogen fluoride from its aqueous solution is provided. A method provides hydrogen fluoride from aqueous solutions, including the reduction of water component of the aqueous solution at an elevated temperature into carbon oxide, carbon dioxide and hydrogen. The condensation and distillation of the obtained hydrogen fluoride and water vapor are characterized by the fact that the mixture of hydrogen fluoride and water is reduced at a temperature of 800 K and above, the molar ratio of carbon to water in the reducing agent is from 0.5 to 4, and using a reducing agent of the general formula C.sub.nH.sub.mO.sub.k, where k≥0, m>0, and n>0, and the reducing agent may be saturated, unsaturated, aromatic hydrocarbons, oxygen-containing organic compounds, their isomers and their mixtures. The method makes it possible to extract hydrogen fluoride from its mixtures with water in any ratio and from azeotropic mixtures.

This patent relates to the mineral waste treatment of the phosphate chemical industry, namely, treatments of hexafluorosilicic acid solutions formed specifically during the process of producing phosphoric acid with hydrogen fluoride. The method for obtaining hydrogen fluoride from hexafluorosilicic acid includes neutralizing the HSA solution with an alkaline agent, yielding a solid salt from the suspension, processing the salt in a fire of a hydrogen-containing fuel and an oxygen-containing oxidant, cooling the combustion products, eliminating the silicon dioxide from these products, condensing the hydrogen fluoride and water, and subsequently extracting the hydrogen fluoride.

Provided are a method for treating sulfur hexafluoride and an apparatus for collecting and treating by-products. The method for treating sulfur hexafluoride, and the apparatus for collecting and treating by-products according to the present invention are a significantly effective method and apparatus capable of safely treating sulfur hexafluoride at low cost.

Extraction of anhydrous hydrogen fluoride from its aqueous solution is provided. A method provides hydrogen fluoride from aqueous solutions, including the reduction of water component of the aqueous solution at an elevated temperature into carbon oxide, carbon dioxide and hydrogen. The condensation and distillation of the obtained hydrogen fluoride and water vapor are characterized by the fact that the mixture of hydrogen fluoride and water is reduced at a temperature of 800 K and above, the molar ratio of carbon to water in the reducing agent is from 0.5 to 4, and using a reducing agent of the general formula C.sub.nH.sub.mO.sub.k, where k≥0, m>0, and n>0, and the reducing agent may be saturated, unsaturated, aromatic hydrocarbons, oxygen-containing organic compounds, their isomers and their mixtures. The method makes it possible to extract hydrogen fluoride from its mixtures with water in any ratio and from azeotropic mixtures.

The present invention provides a novel method for producing hydrogen fluoride which can suppress the occurrence of the pasty state over the whole process of producing hydrogen fluoride, reduce the problem of corrosion caused by sulfuric acid, and improve energy efficiency of the process. A method for producing hydrogen fluoride by reacting calcium fluoride and sulfuric acid comprises: (a) mixing and reacting calcium fluoride and sulfuric acid such that a mixture comprising calcium fluoride particles and sulfuric acid substantially maintains a form of particulate to obtain hydrogen fluoride while supplying sulfuric acid to the calcium fluoride particles at a flow rate of 0.002 to 1 mol/min relative to 1 mol of calcium fluoride to such an amount that a molar ratio of sulfuric acid/calcium fluoride is 0.9 to 1.1.

The present invention provides a novel method for producing hydrogen fluoride which can suppress the occurrence of the pasty state over the whole process of producing hydrogen fluoride, reduce the problem of corrosion caused by sulfuric acid, and improve energy efficiency of the process. A method for producing hydrogen fluoride by reacting calcium fluoride and sulfuric acid comprises: (a) mixing and reacting calcium fluoride and sulfuric acid such that a mixture comprising calcium fluoride particles and sulfuric acid substantially maintains a form of particulate to obtain hydrogen fluoride while supplying sulfuric acid to the calcium fluoride particles at a flow rate of 0.002 to 1 mol/min relative to 1 mol of calcium fluoride to such an amount that a molar ratio of sulfuric acid/calcium fluoride is 0.9 to 1.1.

The present application discloses compositions comprising hydrogen fluoride and fluorinated compounds (e.g., hydrochlorofluorocarbons), wherein the fluorinated compound is present in the composition in an amount effective to form an azeotrope composition or azeotrope-like composition with the hydrogen fluoride.

The present invention relates to a high purity synthetic fluorite (CaF.sub.2). The present invention further relates to a process and an apparatus for preparing said high purity synthetic fluorite (CaF.sub.2), classified as acid grade, starting from fluorosilicic acid H.sub.2SiF.sub.6 (FSA) and calcium carbonate (CaCO.sub.3). Finally, the present invention relates to the use of said high purity synthetic fluorite (CaF.sub.2) in the industrial production of hydrofluoric acid.