Decolouring method of prepared aqueous nitric acid solution

Abstract

The invention relates to a decolouring method of prepared aqueous nitric acid solution. Ammonium carbonate is used as a decolorising agent of nitric acid, and nitric acid is decolorized and bleached by mixing ammonium carbonate and nitric acid. An apparatus of the method comprises an acid preparation tank, an acid cooler, an acid circulating tank and an ejector; the acid preparation tank is provided with a gas outlet, a decolorizing agent charging door, a dilute nitric acid charging door, a dense nitric acid charging door, a recycle acid outlet and a recycle acid inlet; a cooled medium inlet of the acid cooler and the recycle acid outlet of the acid preparation tank are communicated; a cooled medium inlet of the acid cooler is communicated with the recycle acid inlet of the acid preparation tank; the gas outlet of the acid preparation tank is communicated with an extracted medium inlet of the ejector; an outlet of the ejector is communicated with the acid circulating tank; an outlet of the acid circulating tank is communicated with an medium inlet of the ejector. The decolouring method is capable of preparing nitric acid products with different concentration and qualified appearance, and meeting the requirements of different clients; by-product acid mist generated in preparing processes is less; the decolouring method is easy to control, is safe and has environmental protection performance; and the apparatus is convenient for maintenance.

Description

technical field [0001] The invention relates to a decolorization method for preparing an aqueous solution of nitric acid. Background technique [0002] Nitric acid (molecular formula: HNO 3 ) is a strong acid. Pure nitric acid is a colorless liquid with a boiling point of 83°C. It condenses into colorless crystals at -42°C. It is miscible with water and has strong oxidizing and corrosive properties. Depending on the mass fraction of nitric acid in the aqueous solution, It can be divided into 98 acid, 97 acid, 70 acid, 68 acid, 65 acid, 62 acid, 50 acid, 40 acid, etc. It is widely used in manufacturing, coatings, medicine, printing and dyeing, rubber, plastics, metallurgy, national defense and other industries. [0003] The production of nitric acid mainly adopts the following two technical solutions: [0004] 1. Use the production equipment for producing dilute nitric acid to produce medium and high concentration nitric acid. [0005] At present, nitric acid production en...

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Problems solved by technology

[0005] At present, nitric acid production enterprises all use ammonia catalytic oxidation to produce nitric acid. Chinese invention patent 201110323653.X discloses a production method of high-concentration dilute nitric acid, which has a high degree of automation and low production cost, but the disadvantages are: complicated operation and initial investment The cost is very high, hundreds of millions of dollars

The disadvantages are: the 98 acid dilution process is an exothermic reaction, the acid temperature rises very quickly, a large amount of heat is released, accompanied by a large amount of acid mist and it is difficult to recycle, the environment is polluted, and the finished acid is caused by NO 2 High content is reddish brown, resulting in substandard appearance

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