Method for producing ultra-clean high-pure hydrofluoric acid

Abstract

The invention relates to a method for producing ultra-clean high-pure hydrofluoric acid. The method comprises the following steps: (1), emptying air in a system; (2), adding a measured liquid hydrogen fluoride raw material to a rough distillation kettle with a heat exchanger for rough distillation; (3), controlling the inside pressure of the rough distillation kettle to be lower than 0.2MPa and adding an oxidant; (4), repeatedly condensing, refluxing and vaporizing in the rough distillation kettle; (5), pumping gas guided from a top outlet of a water condenser into the bottom of a spraying absorption tower so as to be absorbed by spraying absorption liquid which is sprayed in from the top of the absorption tower; (6), gasifying and pumping hydrofluoric acid into the absorption tower to be absorbed; (7), pumping the hydrofluoric acid at the outlet of the condenser into the absorption tower and using ultra-pure water to absorb into 48 percent to 49 percent of hydrous hydrofluoric acid solution; (8), secondarily rectifying the 48 percent to 49 percent of hydrous hydrofluoric acid solution; and (9), filtering the 48 percent to 49 percent of hydrous hydrofluoric acid solution after secondary rectification at two stages to prepare 48 percent of ultra-clean high-pure hydrofluoric acid finished product. The invention not only improves the purity of the ultra-clean high-pure hydrofluoric acid, but also increases the economic benefits and the environmental-protection benefits.

Description

technical field [0001] The invention relates to a method for producing ultra-clean and high-purity hydrofluoric acid, in particular to a method for producing ultra-clean and high-purity hydrofluoric acid with liquid hydrogen fluoride as the main raw material. Background technique [0002] Hydrofluoric acid (hydrofluoric, HF), relative molecular weight 20.1, colorless liquid or gas; has a strong pungent smell, below 20 ℃, it is a colorless and transparent fuming liquid, and metal oxides, sodium hydroxide and carbonic acid Salt reaction to generate metal fluorine salt, which has the property of dissolving silicon and silicate, generates fluorosulfonic acid with sulfur trioxide or chlorosulfonic acid, reacts with halogenated aromatic hydrocarbons, alcohols, alkenes, and hydrocarbons to generate fluorine-containing organic compounds, and is soluble in water This produces a very corrosive acid. Melting point -83.7°C, boiling point 19.5°C, easily soluble in water, relative densit...

AI Technical Summary

Problems solved by technology

[0003] At present, the reaction of industrial anhydrous hydrofluoric acid and potassium permanganate is generally used, followed by direct rectification and purification to produce ultra-clean and high-purity hydrogen fluoride. The separation of arsenic is not complete, so the ultra-clean and high-purity hydrofluoric acid produced by this method is difficult to apply in VLSI (microelectronics industry), and at the same time, the process parameters in the production process are not easy to control