A method for producing a high-purity hydrogen chloride gas comprises performing a purification process that includes the steps 1) to 3) below on a byproduct hydrogen chloride gas: 1) a crude hydrochloric acid generation step of allowing water to absorb the byproduct hydrogen chloride gas; 2) a volatile organic impurity-removed hydrochloric acid generation step of bringing the crude hydrochloric acid obtained in the step 1) into contact with an inert gas at a liquid temperature of 20 to 45° C. to dissipate volatile organic impurities; and 3) a high-purity hydrogen chloride gas generation step of supplying the volatile organic impurity-removed hydrochloric acid obtained in the step 2) to a distillation column and performing distillation under conditions of a column bottom temperature of higher than 60° C. and 108° C. or lower and a column top temperature of 60° C. or lower to distill out a high-purity hydrogen chloride gas.

A method for producing a high-purity hydrogen chloride gas comprises performing a purification process that includes the steps 1) to 3) below on a byproduct hydrogen chloride gas: 1) a crude hydrochloric acid generation step of allowing water to absorb the byproduct hydrogen chloride gas; 2) a volatile organic impurity-removed hydrochloric acid generation step of bringing the crude hydrochloric acid obtained in the step 1) into contact with an inert gas at a liquid temperature of 20 to 45° C. to dissipate volatile organic impurities; and 3) a high-purity hydrogen chloride gas generation step of supplying the volatile organic impurity-removed hydrochloric acid obtained in the step 2) to a distillation column and performing distillation under conditions of a column bottom temperature of higher than 60° C. and 108° C. or lower and a column top temperature of 60° C. or lower to distill out a high-purity hydrogen chloride gas.

A dehydration method in accordance with an embodiment of the present invention includes: a first dehydration step of bringing hydrogen chloride gas (21) and concentrated sulfuric acid (13A) into contact with each other; and a second dehydration step of bringing hydrogen chloride gas (21A) that has been obtained through the first dehydration step into contact with concentrated sulfuric acid (13B). A concentration of the concentrated sulfuric acid used in the second dehydration step is higher than a concentration of the concentrated sulfuric acid used in the first dehydration step.

The present invention relates to a method of purifying waste hydrochloric acid, and more particularly, to a method of purifying waste hydrochloric acid which includes preparing an extraction solution by dissolving an extractant in an organic solvent (S1), extracting metallic components with the organic solvent by adding the extraction solution to the waste hydrochloric acid (S2), separating a waste hydrochloric acid layer and the organic solvent containing the metallic components (S3), and obtaining purified hydrochloric acid by recovering the separated (fractionated) waste hydrochloric acid layer (S4), wherein the extractant is used in an amount of 40 moles or more based on 1 mole of iron (Fe) included in the waste hydrochloric acid, and the waste hydrochloric acid and the extraction solution are mixed in a volume ratio of 1:0.1 to 1:1.

The apparatus includes one or more cylindrical housings connected to one another, a jacket on an outer side of a housing, an inner cylinder disposed at least in an interior of a first cylindrical housing, a heat insulation gasket, inner members, a corrosive high temperature gas inlet disposed on the heat insulation gasket, a gas and liquid phase outlet disposed at a bottom of the housing or a bottom of a last housing and a coolant inlet and outlet connected to an interior of the jacket. The heat insulation gasket seals the first cylindrical housing and a top of the inner cylinder in the interior of the first cylindrical housing. The inner members are distributed along a wall of the housing, communicate an interior of the jacket with an interior of the housing, and distribute a liquid in the interior of the jacket to the interior of the housing.

A gaseous species can be separated from an aqueous donor mixture and absorbed in an aqueous recipient mixture using a membrane separation apparatus while maintaining a large temperature difference (e.g. greater than 30° C.) between the two aqueous mixtures. A composite membrane is employed which comprises a non-porous membrane adjacent a porous membrane. The non-porous membrane is permeable to the gaseous species. The porous membrane has a porosity greater than 50% and is hydrophobic. In one embodiment, the composite membrane is oriented such that the porous membrane faces the aqueous recipient mixture and is impermeable thereto at the recipient mixture pressure. The invention is particularly suitable for separating chlorine dioxide from chlorine dioxide reaction liquor and absorbing in chilled water.

A method of recycling mixtures of hydrochloric and hydrofluoric acid. In particular, a method of recycling hydrofluoric acid and boron fluoride mixtures. A process for upgrading mixtures of fluoroboron compounds contaminated with chlorides as an aqueous solution of boron fluoride hydrates, including a step of vacuum distillation. Also, a method of producing gaseous boron trifluoride.

A method of recycling mixtures of hydrochloric and hydrofluoric acid. In particular, a method of recycling hydrofluoric acid and boron fluoride mixtures. A process for upgrading mixtures of fluoroboron compounds contaminated with chlorides as an aqueous solution of boron fluoride hydrates, including a step of vacuum distillation. Also, a method of producing gaseous boron trifluoride.

A method for preparing chlorine gas through catalytic oxidation of hydrogen chloride is carried out by one-time hydrogen chloride feeding and multi-stage oxygen feeding, one-time oxygen feeding and multi-stage hydrogen chloride feeding, or both, returning a product gas stream without separation thereof, and optionally carrying out heat insulation means. In the present invention, excessive reaction heat concentration is prevented, therefore, the method of the present invention is a chlorine gas recovery method implemented through the Deacon catalytic oxidation of hydrogen chloride that may be industrialized.

There is provided a process for purifying aluminum ions comprising: reacting an aluminum-containing material with an acid so as to obtain a composition comprising aluminum ions; precipitating said aluminum ions in the form of AlCl.sub.3; optionally converting AlCl.sub.3 into Al(OH).sub.3; and heating said AlCl.sub.3 or said Al(OH).sub.3 under conditions effective for converting AlCl.sub.3 or Al(OH).sub.3 into Al.sub.2O.sub.3 and optionally recovering gaseous HCl so-produced. Aluminum ions so purified are thus useful for preparing various types of alumina.