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Method of preparing high-activity uranium trioxide by thermal denitration of uranyl nitrate

A technology of uranyl nitrate and uranium trioxide, applied in the direction of uranium oxide/hydroxide, etc., can solve the problems of influence and poor activity of uranium oxide, and achieve the advantages of short process flow, good product activity and overcoming poor product activity. Effect

Inactive Publication Date: 2019-04-09
中核二七二铀业有限责任公司
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  • Summary
  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The uranium oxide prepared by the conventional UNH denitrification method is transformed into uranium trioxide only after the crystal lattice is completely disintegrated due to the crystal melting in the preparation process, and there is no inheritance of solid-phase transformation crystal structure and activation of the product by salt decomposition. The crystal form is uncontrolled, the crystal is dense, and the activity of the produced uranium oxide is poor, which has a great impact on the production of hydrofluorination. The activation technology after UNH denitrification is only mastered by a few countries

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  • Method of preparing high-activity uranium trioxide by thermal denitration of uranyl nitrate

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Effect test

Embodiment 1

[0040] (1) The refined uranyl nitrate solution ([U]=85g / l, [HNO 3 ]=4mol / l, miscellaneous items meet the nuclear standard) with 2.0m 3 The / h flow rate is input into the MVR evaporator, and the temperature is controlled at 88°C to obtain a concentrated uranyl nitrate solution with a solubility of 580g / l;

[0041] (2) The concentrated uranyl nitrate solution is input into the cooling crystallizer, the stirring frequency is controlled to 50r / min, the cooling rate is 1°C / min, the final crystallization temperature is 40°C / min, and the crystallization is completed in 1.5h to generate UNH crystals;

[0042] (3) UNH crystals are input into a microwave dryer, the feed stirring frequency is 20Hz, and the dehydration temperature is controlled at 170°C to generate UN powder, which is stored in a vacuum sealed tank;

[0043] (4) The UN powder is conveyed with nitrogen, and the calcination temperature is controlled at 680 ° C in a microwave fixed bed to generate UO 3 Product, product qua...

Embodiment 2

[0045] (1) The refined uranyl nitrate solution ([U]=90g / l, [HNO 3 ]=3.8mol / l, miscellaneous items meet the nuclear standard) with 1.5m 3 The / h flow rate is input into the MVR evaporator, and the temperature is controlled at 90°C to obtain a concentrated uranyl nitrate solution with a solubility of 590g / l;

[0046] (2) The concentrated uranyl nitrate solution is input into the cooling crystallizer, the stirring frequency is controlled to 50r / min, the cooling rate is 1°C / min, the final crystallization temperature is 40°C / min, and the crystallization is completed in 1.5h to generate UNH crystals;

[0047] (3) UNH crystals are input into a microwave dryer, the feed stirring frequency is 20Hz, and the dehydration temperature is controlled at 175°C to generate UN powder, which is stored in a vacuum sealed tank;

[0048] (4) The UN powder is transported with nitrogen, and the calcination temperature is controlled at 690 ° C in a microwave fixed bed to generate UO 3 Product, produc...

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Abstract

The invention belongs to the technical field of preparation of uranium trioxide, and particularly relates to a method of preparing high-activity uranium trioxide by thermal denitration of uranyl nitrate. The method comprises the following steps: step (1) evaporating and concentrating an uranyl nitrate solution to obtain a concentrated uranyl nitrate solution; step (2) conveying the concentrated uranyl nitrate solution to a cooling crystallizer, cooling the concentrated uranyl nitrate solution to a temperature below 40 DEG C, carrying out cooling crystallization to form UO2(NO3)2.6H2O crystals,and returning a saturated solution to an evaporation and concentration device in step (1); step (3) dehydrating the UO2(NO3)2.6H2O crystals obtained in step (2) by microwave drying, and converting the UO2(NO3)2.6H2O crystals obtained in step (3) into UO2(NO3)2 powder; and step (4) generating the UO3 product in a fixed bed by using the UO2(NO3)2 powder obtained in step (3) in a vacuum environmentthrough microwave heating. The method has the advantages of short technological process, no generation of radioactive ammonia-nitrogen wastewater, good product activity and the like, increases the integral level of a uranium purification and conversion technology in the nuclear fuel cycle, and has obvious social and economic benefits.

Description

technical field [0001] The invention belongs to the technical field of uranium trioxide preparation, and in particular relates to a method for preparing high-activity uranium trioxide by thermal denitrification of uranyl nitrate. Background technique [0002] In the uranium nuclear fuel cycle process, uranium fuel mainly includes several processes such as uranium mining and hydrometallurgy processing, uranium purification and conversion, isotope separation, and spent fuel reprocessing. Purification of uranium is to dissolve uranium chemical concentrate in nitric acid to prepare the original solution, and then obtain refined uranyl nitrate solution after extraction, back extraction, etc., and then convert uranyl nitrate into uranium oxide through denitrification, and uranium oxide is one of them. Important intermediate products need to meet a series of process technical indicators, such as impurity content, particle size, activity, etc. As a kind of uranium oxide, uranium tr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G43/01
CPCC01G43/01
Inventor 胡锦明邹发任新辉江志文孙浪唐小群郁东
Owner 中核二七二铀业有限责任公司
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