Method for preparing uranium nitrate through catalytic hydrogenation reduction of uranyl nitrate

Abstract

The invention discloses a method for preparing uranium nitrate (tetravalent uranium) by using catalytic hydrogenation reduction of uranyl nitrate (hexavalent uranium).The method comprises the following steps: mixing uranyl nitrate in a raw material liquid storage tank with nitric acid, feeding the mixture and circulating hydrogen into a high-pressure hydrogenation reactor filled with a catalyst through one end of the reactor, and catalytically reducing uranyl nitrate into uranium nitrate by hydrogen; and flowing the excessive hydrogen and product uranium nitrate out of the reactor through the other end of the reactor; dropwise adding a hydrazine nitrate or hydrazine solution on line into the gas-liquid mixture to convert the solution from an oxidation state to a reduction state, then feeding the gas-liquid mixture into a high-pressure gas-liquid separator for separation, absorbing and separating the nitrogen oxides in a gas phase through alkali liquor, pressurizing hydrogen through a compressor, and then feeding the hydrogen into a high-pressure hydrogen storage tank; and discharging a liquid-phase product from the bottom of a separator and enters a normal-pressure liquid-phase product hydrogen replacement tower, and removing the dissolved hydrogen in the liquid phase by using a nitrogen bubbling device in the tower, so that the safety of a subsequent process is ensured, and the obtained gas enters a high-emission tail gas treatment system.

Description

technical field [0001] The invention relates to a process for preparing tetravalent uranium, in particular to a process for preparing uranium nitrate (quaternary uranium) by catalytically hydrogenating and reducing uranyl nitrate (hexavalent uranium). Background technique [0002] With the large-scale development and application of nuclear power, the clean treatment and efficient recycling of spent nuclear fuel have become the key to the further development of nuclear power. At present, the technology mainly adopted by domestic and foreign reprocessing plants is the Purex process. In this process, the valuable uranium and plutonium elements are firstly extracted into the organic phase through the extraction unit, so as to be separated from most of the splinter elements to achieve the purpose of decontamination; The plutonium is reduced to trivalent and enters the water phase, but the hexavalent uranium remains in the oil phase, thereby achieving efficient separation and pur...

AI Technical Summary

Problems solved by technology

In the relevant reactor, reaction (1) and reaction (2) are a parallel reaction process, if the reaction solution residence time is not enough, reaction (1) can not be carried out completely, and the uranyl nitrate conversion rate is relatively large, but when the reaction If the residence time of the solution is too long, the catalytic decomposition reaction (2) of hydrazine nitrate proceeds transitionally, so that the product liquid changes from a reduced state to an oxidized state, and the tetravalent uranium nitrate generated by the reaction is further oxidized to hexavalent uranyl nitrate, so that the hexavalent uranium nitrate lower conversion rate

Therefore, in order to obtain a higher conversion rate of uranyl nitrate in this process, it is necessary to control the residence time of the reaction solution more accurately so that the conversion rate of hydrazine nitrate is 30%-40%. This special requirement for the residence time of the reactor, Brings great difficulties to the industrialization of the process

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