Double chemical reflux process for exchanging nitrogen oixde and nitric acid to producing N-15

Abstract

The double chemical reflux process for exchanging nitrogen oxide and nitric acid to produce N-15 belongs to the field of high concentration N-15 nitric acid producing technology. Through the chemical reflux in the concentration section and the extraction section, nitrogen oxide and nitric acid produce chemical isotope exchange and circular reflux process is realized. In the extraction section, tail gas nitrogen oxide is recovered with deionized water and oxygen as material in the top refluxer to obtain N-14 nitric acid, and most of the recovered nitric acid is refluxed to the extracting tower for nitrogen isotope exchange to restore the N-15 isotope concentration to natural abundance. The recovered nitric acid is then merged with material nitric cid before being used as the material for the concentration section.

Description

technical field [0001] The invention relates to a method for producing high-concentration nitrogen-15 nitric acid, which belongs to the technical field of high-concentration nitrogen-15 nitric acid production. Background technique [0002] The nitrogen element in all nitrogen-containing substances in nature is composed of two stable isotopes nitrogen-14 and nitrogen-15. Their natural content (called natural abundance) is 99.635% and 0.365% respectively. The difference in atomic structure lies in the nucleus The number of neutrons is different, nitrogen-15 has one more neutron than nitrogen-14. Because they have the same extranuclear properties, chemical properties and most of the physical properties are completely the same, so nitrogen-15 is the best tracer of nitrogen. Nitrogen is the main constituent element of organic life, and nitrogen-15 is a stable isotope (that is, there is no radioactive hazard problem), which can be directly used in the human body, so it has been w...

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Problems solved by technology

[0004] The existing chemical exchange method has the following disadvantages: (1) The toxic nitrogen oxides discharged from the top of the production device can only be sent back to the adjacent nitric acid plant for recycling, and this method cannot be used in places without a nitric acid plant

If it is recovered by alkali absorption, the cost of nitrogen-15 products will be affected due to the low value of recovered products

(2) raw material nitric acid utilization rate is low, the highest is no more than (1.055-1) / 1.055=5.21%, here 1.055 is the separation coefficient of normal temperature and pressure nitrogen oxides and nitric acid chemical exchange concentration nitrogen-15, is a constant, therefore needs Consume a large amount of raw material nitric acid (dilute nitric acid with a concentration of 10 moles). For an annual output of 30 kg of high-concentration nitrogen-15 products, the annual consumption of 10 moles of nitric acid is about 2340 tons

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