Method for removing nitric acid and nitrates from high-level radioactive liquid waste

A high-level waste liquid and nitrate technology, which is applied in radioactive purification, nuclear engineering, etc., can solve the problems of high energy consumption and high requirements for electrode corrosion resistance, and achieve the effects of reducing the risk of explosion, high safety and stability, and easy implementation

Inactive Publication Date: 2015-04-15
NANJING UNIV OF SCI & TECH
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Problems solved by technology

The energy consumption of electrochemical denitrification is large

Method used

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  • Method for removing nitric acid and nitrates from high-level radioactive liquid waste
  • Method for removing nitric acid and nitrates from high-level radioactive liquid waste

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0027] Example 1

[0028] Step 1. Synthesize urea-formaldehyde resin (UF resin) with a 3:1 molar ratio of formaldehyde and urea. Pour all formaldehyde 243.24g into the reaction kettle, add 21.82g of the first batch of urea, adjust the pH to 7.5 and mix and stir. After raising the temperature to 95°C, react for 1 hour; adjust the pH to 4.0 and continue the reaction for 1 hour; lower the temperature to 85°C Add 8.18g of the second batch of urea, adjust the pH to 7.0, and react for 1h; lower the temperature to 75°C, add 30g of the third batch of urea, react for 1h, and obtain UF resin at the end of the reaction.

[0029] Step 2: Configure a nitric acid solution with a concentration of 7mol / L and add NaNO to it 3 , Ba(NO 3 ) 2 , Sr(NO 3 ) 2 , CsNO 3 , Its concentration is respectively 0.076 mol / L, 0.02 mol / L, 0.016 mol / L, 0.037 mol / L to form a simulated high-level liquid waste.

[0030] Step 3. Pour ammonia gas and add ammonium chloride to the simulated high-level liquid waste configur...

Example Embodiment

[0031] Example 2: In Example 1, the concentration of hydrochloric acid in the reaction system was 0.1 mol / L, and other conditions were unchanged, and the removal rate of nitrate reached 27.25%.

Example Embodiment

[0032] Example 3: In Example 1, the concentration of hydrochloric acid in the reaction system was 0.5 mol / L, and other conditions were unchanged, and the removal rate of nitrate reached 39.74%.

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Abstract

The present invention discloses a method for removing nitric acid and nitrates from a high-level radioactive liquid waste. Nitric acid and nitrates are converted to ammonium nitrate; with urea formaldehyde resin as a reducing agent, as NH4NO3 can be easily decomposed into N2, H2O and O2 under the catalysis of H+ and Cl-, the nitric acid and nitrates in the high-level radioactive liquid waste are removed through oxidation-reduction reactions. The method mainly comprises the following steps: (1) UF resins are prepared using a certain ratio of urea and formaldehyde as raw materials and an alkali-acid-alkali process; (2) with ammonia and ammonium salts added, the nitric acid in the high-level radioactive liquid waste can be neutralized and the produced nitrates can be converted into ammonium nitrate which can be easily decomposed by a metathetical reaction; (3) the UF resins are added into the high-level radioactive liquid waste and conduct a denitration reaction under the catalysis of H+ and Cl-. Compared with traditional denitration of high-level radioactive liquid waste, the method in the present invention has a more stable reaction and a lower explosion risk, produces a small amount of NO2, and at the same time the denitrated objects can be both nitric acid and nitrates in the high-level radioactive liquid waste.

Description

technical field [0001] The invention relates to a denitrification method for high-level waste liquid in the nuclear industry field, in particular to a method using ammonium nitrate as an oxidizing agent and urea-formaldehyde resin as a reducing agent. + and Cl - Under the catalytic action of the catalyst, redox reaction is carried out to remove nitric acid and nitrate in high-level radioactive waste liquid. Background technique [0002] High-level waste liquid mainly refers to the aqueous phase extraction raffinate produced by the spent fuel reprocessing plant, which contains a large amount of NaNO 3 , Nd(NO 3 ) 3 , ZrO(NO 3 ) 3 In order to prevent precipitation, the concentration of nitric acid should be maintained above 2M. High-level radioactive waste has the characteristics of strong radioactivity, high heating rate, and high corrosiveness. A small amount of organic matter remaining after the Purex process cycle can undergo uncontrolled combustion-explosion reacti...

Claims

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Application Information

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IPC IPC(8): G21F9/04G21F9/06
CPCG21F9/06
Inventor 唐双凌周蓉杨云飞李燕英鲁彤王泸
Owner NANJING UNIV OF SCI & TECH
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