Nitric acid two-step bleaching process and its device

Abstract

The invention provides a nitric acid two-step bleaching technology and device. According to the adopted technical scheme, the technology comprises the steps that 1, a nitric acid preparation groove for nitric acid preparation is vacuumized to micro-negative pressure; 2, hydrogen peroxide is added into a nitric acid solution in the nitric acid preparation groove, and the mixture is evenly stirred; 3, redundant NO2 is recycled at the outlet end of the nitric acid preparation groove; 4, a urea solution is evenly added into the nitric acid preparation groove. Compressed air is used as power, the hydrogen peroxide and the urea solution pass through a gas distributor 20 cm away from the bottom of the nitric acid preparation groove and then evenly enter the nitric acid preparation groove, the hydrogen peroxide reacts with NO2 in nitric acid at first to be converted into nitric acid, meanwhile, NO2 in nitric acid escapes out thoroughly to enter a negative pressure device, and concentrated nitric acid is bleached; then a small amount of or subsequently-produced NO2 reacts with a subsequently-added urea solution, so that the nitric acid solution has no color for a long time, the content of NO2 in the nitric acid solution is rapidly controlled, and the problem that NO2 content exceed standards is solved.

Description

technical field [0001] The invention relates to the technical field of production and preparation of nitric acid, in particular to a two-step nitric acid bleaching process and a device thereof. Background technique [0002] Nitric acid is one of the most important chemical products. Nitric acid is mainly produced by ammonia oxidation in industry, and is used to make fertilizers, explosives, nitrates, etc. Pure nitric acid is a colorless transparent liquid, and industrial nitric acid solution is brown due to dissolved nitrogen dioxide. [0003] At present, nitric acid is used in all walks of life, but different industries have different requirements on the concentration of nitric acid. For example, the production of ammonium nitrate by neutralization requires nitric acid with a concentration of 37-43% as a raw material, while the production of ammonium nitrate by pressurization requires a concentration of 60%. Nitric acid is used as raw material; the IT industry needs nitric...

AI Technical Summary

Problems solved by technology

The concentration of nitric acid produced by the above device may not be able to meet the needs of customers. Customers still need to prepare nitric acid aqueous solutions of different concentrations by themselves. However, in the process of preparing nitric acid aqueous solution, the mixture of concentrated nitric acid and dilute nitric acid will generate heat, which will cause a small amount of nitric acid to decompose. Its reaction formula is 4HNO 3 ==2H 2 O +4NO 2 +O 2 , so that the dilute nitric acid solution turns red, even if the colorless dilute nitric acid decomposes NO in a small amount during transportation 2 ,polluted environment

[0005] Conventional dilute nitric acid bleaching often utilizes air or steam, namely "cold bleaching" or "hot bleaching". NO produced during storage and transportation 2

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