Preparation method of nitrosyl sulfuric acid and method for separating sulfuric acid and phosphoric acid in industrial waste acid

Abstract

The invention discloses a preparation method of nitrosyl sulfuric acid and a method for separating sulfuric acid and phosphoric acid in industrial waste acid. The preparation method comprises the following steps: (1), mixing sulfur with a sulfuric acid solution A, performing warming reaction to generate sulfur dioxide gas, and performing centrifugal treatment on waste acid after reaction to obtain waste acid containing a lot of phosphoric acid; and (2), drying the sulfur dioxide gas, and enabling the dried sulfur dioxide gas to react with a mixed nitric acid solution B in a multistage-series falling-film absorption tower, thereby obtaining nitrosyl sulfuric acid. According to the preparation method of nitrosyl sulfuric acid, disclosed by the invention, industrial waste acid containing nitric acid and sulfuric acid is used as a reaction raw material to realize waste recycling, and meanwhile the purpose of concentrating the phosphoric acid in the waste acid is achieved, so that an economical and effective treatment method is provided for the industrial waste acid.

Description

technical field [0001] The invention relates to the field of chemical production, in particular to a preparation of nitrosyl sulfuric acid and a method for separating sulfuric acid and phosphoric acid from industrial waste acids. Background technique [0002] Diazotization is an important reaction unit in organic synthesis, and sodium nitrite is a commonly used raw material for diazotization reaction. When there is an electron-withdrawing group on the benzene ring, the activity of the amino group is reduced, and a diazotization raw material with higher activity, nitrosylsulfuric acid, is needed. Compared with sodium nitrite, as a diazotization agent, nitrosyl sulfuric acid will not generate sodium sulfate salt during diazotization reaction, which is convenient for the concentrated recovery of dilute sulfuric acid in the subsequent process. [0003] Nitrosylsulfuric acid is a very unstable compound and usually needs to be dissolved in a certain concentration of sulfuric acid...

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Problems solved by technology

This method is to firstly oxidize ammonia to nitrogen oxide gas, and then react with oleum in a concentrated sulfuric acid system to produce nitrosyl sulfuric acid. This method requires a high level of production technology and is fully automated. Large production capacity, tail gas treatment is also relatively simple, the content of the obtained product nitrosyl sulfuric acid can reach more than 70%, but the production of nitrosyl sulfuric acid by direct absorption method is currently only available when the absorption pressure is 0.3MPa, and the use of sieve plate absorption Nitrosyl sulfuric acid is produced by tower absorption reaction. This technology is imported from abroad. There are problems such as difficult operation and adjustment, high energy consumption and unsatisfactory treatment of environmentally friendly nitrogen oxide gas.

[0008] In my country's industrial production, a large amount of industrial waste acid can be produced every year, especially the waste acid produced by nitration reaction (nitration waste acid) and the waste acid produced by bromination reaction (bromination waste acid). Among them, the nitration waste acid mainly contains sulfuric acid and nitric acid, while brominated waste acid mainly contains sulfuric acid and phosphoric acid. This kind of industrial waste acid has high acidity and is difficult to handle and utilize. The discharge of this industrial waste acid will cause environmental pollution and waste of resources.

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