Denitration UO3 continuous multistage hydration activation system and method

Abstract

The invention provides a denitration UO3 continuous multi-stage hydration activation system and a denitration UO3 continuous multi-stage hydration activation method, belongs to the technical field of uranium purification and conversion, and is used for solving the problems that the specific surface area of activated UO3 obtained by an existing denitration UO3 activation method is remarkably different, and the activity needs to be further improved. The system comprises a first-stage hydration reactor, a second-stage hydration reactor, a third-stage hydration reactor and a fourth-stage hydration reactor which are sequentially connected in series, the rotary drum vacuum filter is communicated with an outlet of the fourth-stage hydration reactor; the dryer is communicated with an outlet of the rotary drum vacuum filter; the desalted water tank is communicated with the first-stage hydration reactor; the dryer comprises a first drying chamber at the temperature of 200-280 DEG C, a second drying chamber at the temperature of 290-370 DEG C, a first dewatering chamber at the temperature of 380-420 DEG C and a second dewatering chamber at the temperature of 380-480 DEG C which are sequentially arranged in the material flowing direction. Denitrated UO3 activated by the system is uniform in specific surface area and high in activity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of uranium purification conversion, and particularly relates to a continuous multi-stage hydration activation system and method for denitration UO3. BACKGROUND

[0002] Currently, the uranium conversion production from uranium oxide to UF6 adopts the UO2(NO3)2·6H2O crystal denitration reduction method (i.e. UNH method), the UNH method does not consume other reagents, basically does not produce waste liquid and solid waste, and has a short process flow. Especially in the preparation of UO2, the front-end denitration UO3 is used as raw material to prepare UO2 through reduction, and this process has the advantages of short process flow and no liquid waste, etc., and has gradually become a representative process route in line with the development direction of the industry technology. For example, the UNH denitration-reduction process route adopted by the Cameco company in Canada is to first denitrate the UNH solution in a multi-stage stirring tank, and then also use the fluidized bed to prepare UO2 from the denitration UO3. However, the activity of the denitration UO3 is poor, which is not conducive to the subsequent reduction and hydrofluorination conversion process, causing a large waste of hydrogen and fluorine gas. Therefore, it is of great significance to improve the activity of the denitration UO3 in the subsequent conversion process.

[0003] Currently, the methods for improving the activity of the denitration product UO3 mainly include grinding-screening, adding sulfate, hydration activation, and oxidation-reduction, etc. In order to fundamentally improve the activity of the UNH denitration product, it is necessary to chemically treat the denitration UO3 to completely destroy the crystal structure of the original particles, so as to convert them into active UO3. The existing chemical activation methods include oxidation-reduction method and hydration activation method. The oxidation-reduction method needs to reduce UO3 into UO2, and then oxidize it into U3O8, and the process is relatively complex, and there is no application example in industry. Adding sulfate to the UO2(NO3)2 solution to improve the activity of UO3 cannot fundamentally change the crystal structure of UO3 and the mechanism of the growth of the spray denitration particles, and the improvement of the activity of UO3 has certain limits. The hydration activation method is simple to operate, only needs an appropriate amount of water to react with UO3 to form UO3 hydrate, and then the UO3 hydrate is dried to obtain high-activity UO3, and this method can fundamentally solve the problem of low activity caused by the growth of the spray denitration particles.

[0004] CN103910385A discloses a method for improving the activity of denitration UO3 by atomizing and spraying the denitration UO3 with deionized water to generate dihydrate uranium trioxide (UO3·2H2O), and then effectively improving the activity of the denitration UO3 through drying and dehydration. However, in the atomizing and spraying process, the reaction process of UO3 with deionized water is not uniform, the specific surface area of the generated UO3 has significant differences, and the activity of the denitration UO3 still needs to be further improved. SUMMARY

[0005] The technical problem solved by the present application is to provide a denitration UO3 continuous multi-stage hydration activation system and method, which can change the crystal structure of UO3 particles, fundamentally improve the activity of UO3, reduce resource waste, achieve the purpose of energy saving and efficiency improvement, and obtain UO3 with uniform specific surface area.

[0006] To solve the above technical problems, the technical scheme of the present application is as follows: In a first aspect, the present application provides a denitration UO3 continuous multi-stage hydration activation system, comprising: a first-stage hydration reactor, a second-stage hydration reactor, a third-stage hydration reactor and a fourth-stage hydration reactor connected in series; deionized water and denitration UO3 are delivered to the first-stage hydration reactor, the second-stage hydration reactor, the third-stage hydration reactor and the fourth-stage hydration reactor for reaction, and a reacted uranium trioxide hydrate slurry is obtained; a rotary drum vacuum filter in communication with the outlet of the fourth-stage hydration reactor, used for filtering the uranium trioxide hydrate slurry to obtain solid material; a dryer in communication with the outlet of the rotary drum vacuum filter, used for drying and dehydrating the solid material filtered by the rotary drum vacuum filter; a desalted water tank in communication with the first-stage hydration reactor, used for providing water to the first-stage hydration reactor; The dryer comprises a first drying chamber, a second drying chamber, a first dehydration chamber and a second dehydration chamber arranged in series along the material flow direction; the temperature of the first drying chamber is 200-280℃, the temperature of the second drying chamber is 290-370℃, the temperature of the first dehydration chamber is 380-420℃, and the temperature of the second dehydration chamber is 380-480℃.

[0007] Optionally, the rotary drum filtrate channel of the rotary drum vacuum filter is in communication with the desalted water tank.

[0008] Optionally, a dust remover and a condenser are arranged in series along the tail gas flow direction at the tail gas outlet of the dryer.

[0009] Optionally, the condensate outlet of the condenser is in communication with the desalted water tank.

[0010] In a second aspect, the present application provides a denitration UO3 continuous multi-stage hydration activation method, which adopts the above-mentioned denitration UO3 continuous multi-stage hydration activation system, and the denitration UO3 continuous multi-stage hydration activation method comprises: Step (A), the water from the desalted water tank is mixed with the denitration UO3 in the first stage of the hydration reactor to perform the first stage of the hydration reaction; after the first stage of the hydration reaction is completed, the slurry in the first stage of the hydration reactor enters the second stage of the hydration reactor to perform the second stage of the hydration reaction, and water and denitration UO3 are again fed into the first stage of the hydration reactor; after the second stage of the hydration reaction is completed, the slurry in the second stage of the hydration reactor enters the third stage of the hydration reactor to perform the third stage of the hydration reaction, and the slurry in the first stage of the hydration reactor enters the second stage of the hydration reactor, and water and denitration UO3 are again fed into the first stage of the hydration reactor; after the third stage of the hydration reaction is completed, the slurry in the third stage of the hydration reactor enters the fourth stage of the hydration reactor to perform the fourth stage of the hydration reaction, and the slurry in the first stage of the hydration reactor enters the second stage of the hydration reactor, and the slurry in the second stage of the hydration reactor enters the third stage of the hydration reactor, and water and denitration UO3 are again fed into the first stage of the hydration reactor (1); in succession, the material is continuously subjected to the four stages of the hydration reaction. Step (B), the slurry discharged from the fourth stage of the hydration reactor enters the rotary drum vacuum filter to filter the slurry, and the filter cake enters the first drying chamber, the second drying chamber, the first dewatering chamber and the second dewatering chamber in the dryer in succession to be subjected to the first drying treatment, the second drying treatment, the first dewatering treatment and the second dewatering treatment in succession, so as to obtain the hydrated and activated UO3.

[0011] Optionally, in step (B), the filtrate obtained by filtration enters the desalted water tank through the rotary drum filtrate channel for recycling.

[0012] Optionally, in step (B), the water vapor tail gas formed in the drying and dewatering process is subjected to dust removal through the dust remover and then enters the condenser for condensation, and the condensed water is discharged into the desalted water tank for recycling.

[0013] Optionally, in the first stage of the hydration reactor, the mass content of the denitration UO3 in the mixed slurry formed by the water and the denitration UO3 is 40-60%.

[0014] Optionally, the reaction temperature of the first stage of the hydration reaction, the second stage of the hydration reaction, the third stage of the hydration reaction and the fourth stage of the hydration reaction is independently 25-40℃, and the reaction time is independently 0.5-2h.

[0015] Optionally, the time of the first drying treatment, the second drying treatment, the first dewatering treatment and the second dewatering treatment is independently 2-8h.

[0016] The above scheme of the present application at least has the following beneficial effects: (1) The mixture of denitration UO3 and water (solid content of the mixture is 40-60%) is reacted in the continuous four-stage series hydration reactor, the operation step and reaction process are simple, the whole process is continuously operated, the transformation of the crystal structure of the material can be realized, the specific surface area of UO3 is improved, so that UO3 has higher activity, and the four-stage series hydration reactor and the direct mixing of denitration UO3 and water make denitration UO3 and water fully contact, the mixing process is uniform, and the specific surface area of UO3 is more uniform.

[0017] (2) The present application adopts stepwise segmented temperature drying and dehydration, accurately controls the temperature of four independent chambers in the dryer, and makes the material pass through the segmented temperature intervals of 200-280 DEG C, 290-370 DEG C, 380-420 DEG C and 380-480 DEG C in sequence to complete drying and dehydration, so that the controllability and uniformity of drying and dehydration in different stages are ensured.

[0018] (3) The activated UO3 obtained by the system and method has higher activity, the specific surface area is as high as 3.0 m 2 / g, and the bulk density is reduced to 2.0 g / cm 3 .

[0019] (4) The system of the present application can be continuously operated without interruption, the process is continuous, the production efficiency is significantly improved, and the product quality stability is ensured.

[0020] (5) The system of the present application can make denitration UO3 and water fully hydrate, and the mother liquor and condensate water generated in the solid-liquid separation in the filter and the drying and dehydration in the dryer can be recycled, and no waste liquid is generated in the whole process. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of the denitration UO3 continuous multi-stage hydration activation system of the present application.

[0022] Reference signs: 1-First stage hydration reactor; 2-Second stage hydration reactor; 3-Third stage hydration reactor; 4-Fourth stage hydration reactor; 5-Drum vacuum filter; 6-Dryer; 7-Dust remover; 8-Condenser; 9-Desalted water tank. DETAILED DESCRIPTION

[0023] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0024] As Figure 1As shown, the present application provides a continuous multi-stage hydration activation system for denitration UO3, comprising: The first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3 and the fourth-stage hydration reactor 4 are connected in series; the lower overflow port of the first-stage hydration reactor 1 is communicated with the upper feed port of the second-stage hydration reactor 2, the lower overflow port of the second-stage hydration reactor 2 is communicated with the upper feed port of the third-stage hydration reactor 3, and the lower overflow port of the third-stage hydration reactor 3 is communicated with the upper feed port of the fourth-stage hydration reactor 4; deionized water and denitration UO3 are delivered into the first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3 and the fourth-stage hydration reactor 4 for reaction, so as to obtain the reacted uranium trioxide hydrate slurry; The rotary drum vacuum filter 5 communicated with the outlet of the fourth-stage hydration reactor 4 is used for filtering the uranium trioxide hydrate slurry, so as to obtain the solid material; The dryer 6 communicated with the outlet of the rotary drum vacuum filter 5 is used for drying and dehydrating the solid material filtered by the rotary drum vacuum filter 5; The desalted water tank 9 communicated with the first-stage hydration reactor 1 is used for providing water for the first-stage hydration reactor 1; The dryer 6 comprises the first drying chamber, the second drying chamber, the first dehydration chamber and the second dehydration chamber which are arranged in sequence along the material flow direction; the temperature of the first drying chamber is 200-280℃, the temperature of the second drying chamber is 290-370℃, the temperature of the first dehydration chamber is 380-420℃, and the temperature of the second dehydration chamber is 380-480℃.

[0025] Exemplarily, the metering pump is arranged between the desalted water tank 9 and the first-stage hydration reactor 1.

[0026] Exemplarily, the system further comprises the vacuum material suction device connected with the first-stage hydration reactor 1, which is used for sucking the denitration UO3 material into the bin of the first-stage hydration reactor 1.

[0027] Exemplarily, the star feeder is arranged on the bin of the first-stage hydration reactor 1, which is used for controlling the feeding amount of the denitration UO3 material.

[0028] Exemplarily, the stirring devices are arranged in the first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3 and the fourth-stage hydration reactor 4, which are used for stirring the materials.

[0029] Exemplarily, the frequency converter is arranged on the stirring device, which is used for adjusting the stirring speed of the stirring device.

[0030] Exemplarily, a screw conveyor is arranged between the fourth stage hydration reactor 4 and the rotary drum vacuum filter 5, for conveying the material in the fourth stage hydration reactor 4 to the rotary drum vacuum filter 5 for solid-liquid separation.

[0031] Exemplarily, the rotary drum filtrate channel of the rotary drum vacuum filter 5 is communicated with the desalted water tank 9, and the filtrate filtered out by the rotary drum vacuum filter 5 enters the desalted water tank 9 through the rotary drum filtrate channel for recycling.

[0032] Exemplarily, a screw conveyor is arranged between the rotary drum vacuum filter 5 and the dryer 6, for conveying the solid material filtered out by the rotary drum vacuum filter 5 to the dryer 6 for drying and dewatering.

[0033] Exemplarily, a stirring paddle and a scraper are arranged in each cavity of the dryer 6, for stirring the material and making the material fully contact with the hot gas flow.

[0034] Exemplarily, the tail gas outlet of the dryer 6 is sequentially provided with a dust remover 7 and a condenser 8 along the tail gas flow direction, for dust removal and condensation of the tail gas of the dryer 6.

[0035] Exemplarily, a filter is arranged between the dryer 6 and the dust remover 7, for filtering the tail gas, so that the fine material in the tail gas returns to the dryer 6.

[0036] Exemplarily, a high-pressure induced draft fan connected with the condenser 8 is further arranged, for leading the exhaust gas in the condenser 8 out.

[0037] Exemplarily, the condensate outlet of the condenser 8 is communicated with the desalted water tank 9, for returning the condensate formed in the condenser 8 to the desalted water tank 9 for recycling, and the uncondensed exhaust gas is sent to the subsequent tail gas treatment pipeline.

[0038] When the denitration UO3 is activated by using the continuous multi-stage hydration activation system for denitration UO3, the denitration UO3 material is sucked into the top bin of the first hydration reactor 1 by the vacuum suction device, the bin is connected with the star feeder to control the feeding amount of the denitration UO3 material, the deionized water is conveyed from the desalted water tank 9 to the first hydration reactor 1 by the centrifugal pump, the four-stage reactors are connected in series to form a reaction system, the material is continuously discharged and fed between the reactors through the overflow port to ensure the reaction sufficiency; the slurry after the reaction is discharged from the overflow port of the fourth stage reactor, is conveyed to the rotary drum vacuum filter 5 by the screw conveyor to complete the solid-liquid separation, the filtrate is conveyed to the desalted water tank 9 by the centrifugal pump for recycling, and the separated solid material is conveyed to the dryer 6 by the screw conveyor for drying and dewatering; the tail gas of the dryer 6 is purified by the filter, the dust remover 7, the condenser 8 and the high-pressure induced draft fan, the condensate produced by the condenser 8 enters the desalted water tank 9 through the pipeline for recycling.

[0039] The application further provides a continuous multi-stage hydration activation method of denitration UO3, which adopts the continuous multi-stage hydration activation system of denitration UO3. In step (A), the water from the desalination water tank 9 is mixed with the denitration UO3 in the first-stage hydration reactor 1 to perform a first-stage hydration reaction; after the first-stage hydration reaction is completed, the slurry in the first-stage hydration reactor enters the second-stage hydration reactor 2 to perform a second-stage hydration reaction, and water and denitration UO3 are fed into the first-stage hydration reactor 1 again; after the second-stage hydration reaction is completed, the slurry in the second-stage hydration reactor 2 enters the third-stage hydration reactor 3 to perform a third-stage hydration reaction, and the slurry in the first-stage hydration reactor 1 enters the second-stage hydration reactor 2, and water and denitration UO3 are fed into the first-stage hydration reactor 1 again; after the third-stage hydration reaction is completed, the slurry in the third-stage hydration reactor 3 enters the fourth-stage hydration reactor 4 to perform a fourth-stage hydration reaction, and the slurry in the first-stage hydration reactor 1 enters the second-stage hydration reactor 2, the slurry in the second-stage hydration reactor 2 enters the third-stage hydration reactor 3, and water and denitration UO3 are fed into the first-stage hydration reactor 1 again; and the material is sequentially subjected to four-stage hydration reactions continuously. In step (B), the slurry discharged from the fourth-stage hydration reactor 4 enters the rotary drum vacuum filter 5 to perform filtration on the slurry, and the filter cake sequentially enters the first drying chamber, the second drying chamber, the first dewatering chamber and the second dewatering chamber in the dryer 6 to sequentially perform first drying treatment, second drying treatment, first dewatering treatment and second dewatering treatment, so as to obtain hydrated and activated UO3.

[0040] Specifically, step (A) comprises: starting the stirring devices of the first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3, and the fourth-stage hydration reactor 4, starting the metering pump to add the deionized water in the desalination water tank 9 into the first-stage hydration reactor 1, starting the vacuum suction device to suck the denitrated UO3 into the bin at the top of the first-stage hydration reactor 1, adjusting the frequency control of the star feeder to control the feeding amount of the denitrated UO3, adjusting the stirring speed of the stirring devices in the first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3, and the fourth-stage hydration reactor 4 through the frequency converter, so that the denitrated UO3 and the deionized water form a mixed slurry, opening the overflow port of the first-stage hydration reactor 1 after the first-stage hydration reaction of the slurry in the first-stage hydration reactor 1 is completed, and closing the overflow port of the first-stage hydration reactor 1 after the slurry is discharged into the second-stage hydration reactor 2, at the same time, the star feeder and the metering pump start feeding and reacting in the first-stage hydration reactor 1, opening the overflow port of the second-stage hydration reactor 2 after the second-stage hydration reaction in the second-stage hydration reactor 2 is completed, discharging the slurry into the third-stage hydration reactor 3, closing the overflow port of the second-stage hydration reactor 2 after the slurry in the second-stage hydration reactor 2 is discharged, and at the same time, receiving the material discharged from the first-stage hydration reactor 1. By analogy, the slurry sequentially passes through the third-stage hydration reactor 3 and the fourth-stage hydration reactor 4 until the reaction is completed, opening the overflow port of the fourth-stage hydration reactor 4, and after the slurry is discharged from the overflow port of the fourth-stage hydration reactor 4, the slurry is transported to the rotary drum vacuum filter 5 for solid-liquid separation.

[0041] In order to fully hydrate the water and the denitrated UO3, preferably, in the first-stage hydration reactor 1, the mass content of the denitrated UO3 in the mixed slurry formed by the water and the denitrated UO3 is 40-60%, for example, 40%, 45%, 50%, 55%, or 60%.

[0042] For example, the reaction temperature of the first-stage hydration reaction, the second-stage hydration reaction, the third-stage hydration reaction, and the fourth-stage hydration reaction is independently 25-40°C, for example, 25°C, 30°C, 35°C, or 40°C; and the reaction time is independently 0.5-2h, for example, 0.5h, 1.0h, 1.5h, or 2h.

[0043] For example, the total time of the first-stage hydration reaction, the second-stage hydration reaction, the third-stage hydration reaction, and the fourth-stage hydration reaction is 2-8h, for example, 2h, 3h, 4h, 5h, 6h, 7h, or 8h.

[0044] For example, in step (B), the filtrate obtained by filtration is circulated into the desalination water tank 9 through the rotary drum filtrate channel.

[0045] Specifically, in step (B), the process of filtering the slurry by the rotary drum vacuum filter 5 includes: feeding the slurry to be separated into a slurry tank of the rotary drum vacuum filter 5, stirring in the slurry tank to avoid the solid phase from settling to reduce the filter cake resistance, the liquid phase penetrating into the rotary drum filtrate channel under the action of vacuum suction, and the solid material being intercepted to form a uniform filter cake with a thickness of ≤1 cm; when the rotary drum rotates to the unloading area, the solid material is scraped off by a scraper and transported to the dryer 6 through a screw conveyor, the filtrate is transported to the desalted water tank 9 for collection and recycling through a centrifugal pump, and the filter cloth follows the rotary drum to rotate uniformly and continuously after unloading, so that the continuous operation of solid-liquid separation is realized.

[0046] Illustratively, in step (B), the water vapor tail gas formed in the drying and dewatering process is subjected to dust removal by the dust remover 7 and then enters the condenser 8 for condensation, and the condensed water is discharged into the desalted water tank 9 for recycling.

[0047] Illustratively, in step (B), the time of the first drying treatment, the second drying treatment, the first dewatering treatment and the second dewatering treatment is independently 2-8 h, for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h or 8 h.

[0048] In step (B), the process of drying and dewatering the filter cake by the dryer 6 includes: the solid material transported to the dryer 6 by the screw conveyor is continuously turned over under the driving of the stirring paddle and the scoop plate, fully contacts with the hot gas flow for drying and dewatering, and is gradually pushed forward by the screw conveying device to ensure the continuity of the operation process; the dryer has four independent temperature control chambers, and the material sequentially passes through the first drying treatment of the first drying chamber at 200-280℃ (for example, 200℃, 220℃, 240℃, 260℃ or 280℃), the second drying treatment of the second drying chamber at 290-370℃ (for example, 290℃, 300℃, 320℃, 340℃ or 370℃), the first dewatering treatment of the first dewatering chamber at 380-420℃ (for example, 380℃, 390℃, 400℃, 410℃ or 420℃), and the second dewatering treatment of the second dewatering chamber at 380-480℃ (for example, 380℃, 400℃, 420℃, 440℃, 460℃ or 480℃) by the screw pushing, so that the drying process is accurately controlled by the segmented temperature control to ensure the controllability and uniformity of the drying and dewatering in different stages, and finally the material with a porous structure is formed; the dust-containing tail gas generated in the drying process is sequentially treated by the filter, the dust remover 7 and the condenser 8, the fine powder after filtration is returned to the dryer 6, and the purified waste gas is sent into the tail gas treatment pipeline by the high-pressure induced draft fan; the whole process realizes the efficient and continuous operation of the whole process of material drying, conveying and waste gas treatment, and there is no interruption between the links.

[0049] The present application realizes the preparation of high-activity UO3 material, and has the advantages of simple operation steps, controllable process, high material activity and high production efficiency.

[0050] The denitration UO3 continuous multi-stage hydration activation system and method of the present application will be further described below through specific embodiments.

[0051] Embodiment 1 The present embodiment provides a denitration UO3 continuous multi-stage hydration activation system, comprising: a first-stage hydration reactor 1, a second-stage hydration reactor 2, a third-stage hydration reactor 3, and a fourth-stage hydration reactor 4 connected in sequence; a rotary drum vacuum filter 5 connected to the outlet of the fourth-stage hydration reactor 4 for filtering uranium trioxide hydrate slurry; a dryer 6 connected to the outlet of the rotary drum vacuum filter 5 for drying and dehydrating the solid material filtered by the rotary drum vacuum filter 5; and a desalted water tank 9 connected to the first-stage hydration reactor 1 for providing water to the first-stage hydration reactor 1. The dryer 6 comprises a first drying chamber, a second drying chamber, a first dehydration chamber, and a second dehydration chamber arranged in sequence along the material flow direction; the temperature of the first drying chamber is 200-280℃, the temperature of the second drying chamber is 290-370℃, the temperature of the first dehydration chamber is 380-420℃, and the temperature of the second dehydration chamber is 380-480℃.

[0052] A metering pump is arranged between the desalted water tank 9 and the first-stage hydration reactor 1. A vacuum material suction device is further arranged connected to the first-stage hydration reactor 1. A star feeder is arranged on the stock bin of the first-stage hydration reactor 1. Stirring devices are arranged in the first-stage hydration reactor 1, the second-stage hydration reactor 2, the third-stage hydration reactor 3, and the fourth-stage hydration reactor 4. A frequency converter is arranged on the stirring device. A screw conveyor is arranged between the fourth-stage hydration reactor 4 and the rotary drum vacuum filter 5. The rotary drum filtrate channel of the rotary drum vacuum filter 5 is connected to the desalted water tank 9. A screw conveyor is arranged between the rotary drum vacuum filter 5 and the dryer 6. Stirring paddles and scoops are arranged in each chamber of the dryer 6. A dust remover 7 and a condenser 8 are arranged in sequence along the tail gas flow direction at the tail gas outlet of the dryer 6. A filter is arranged between the dryer 6 and the dust remover 7. A high-pressure induced draft fan connected to the condenser 8 is further arranged. The condensate outlet of the condenser 8 is connected to the desalted water tank 9.

[0053] Embodiment 2 The present embodiment provides a denitration UO3 continuous multi-stage hydration activation method, which adopts the denitration UO3 continuous multi-stage hydration activation system of Embodiment 1, comprising: Step (1), open the stirring device of the first stage hydration reactor 1, the second stage hydration reactor 2, the third stage hydration reactor 3 and the fourth stage hydration reactor 4, start the metering pump to add deionized water in the desalination water tank 9 into the first stage hydration reactor 1, open the vacuum suction device to suck the denitrated UO3 into the material bin at the top of the first stage hydration reactor 1, adjust the frequency control of the star feeder to control the feeding amount of the denitrated UO3, and the mass content of the denitrated UO3 in the mixed slurry is 50%; the temperature of the first stage hydration reactor 1 is 30℃, the temperature of the second stage hydration reactor is 30℃, the temperature of the third stage hydration reactor 3 is 30℃, and the temperature of the fourth stage hydration reactor 4 is 30℃, and the stirring speed of the stirring device in the first stage hydration reactor 1, the second stage hydration reactor 2, the third stage hydration reactor 3 and the fourth stage hydration reactor 4 is adjusted through the frequency converter to make the denitrated UO3 and the deionized water form a uniformly mixed slurry, the overflow port of the first stage hydration reactor 1 is opened after the first stage hydration reaction of the slurry in the first stage hydration reactor 1, the slurry is discharged into the second stage hydration reactor 2, the overflow port of the first stage hydration reactor 1 is closed, at the same time, the star feeder and the metering pump start to feed and react in the first stage hydration reactor 1, the overflow port of the second stage hydration reactor 2 is opened after the second stage hydration reaction in the second stage hydration reactor 2, the slurry is discharged into the third stage hydration reactor 3, the overflow port of the second stage hydration reactor 2 is closed after the slurry in the second stage hydration reactor 2 is discharged, and at the same time, the material discharged from the first stage hydration reactor 1 is accepted. By analogy, the slurry passes through the third stage hydration reactor 3 and the fourth stage hydration reactor 4 in turn until the reaction is completed. The time of the first stage hydration reaction is 1.5h, the time of the second stage hydration reaction is 1.5h, the time of the third stage hydration reaction is 1.5h, and the time of the fourth stage hydration reaction is 1.5h. The overflow port of the fourth stage hydration reactor 4 is opened, and after the slurry is discharged from the overflow port of the fourth stage hydration reactor 4, it is transported to the rotary drum vacuum filter 5 for solid-liquid separation by the screw conveyor.

[0054] Step (2), the process of filtering the slurry by the rotary drum vacuum filter 5 includes: sending the slurry to be separated into the slurry tank of the rotary drum vacuum filter 5, stirring the stirring device in the slurry tank to avoid the settlement of the solid phase to reduce the filter cake resistance, the liquid phase penetrates through the filter cloth into the rotary drum filtrate channel under the action of the vacuum suction force, and the solid material is intercepted to form a uniform filter cake ≤1cm, when the rotary drum rotates to the discharge area, the scraper scrapes off the solid material and transports it to the dryer 6 through the screw conveyor, the filtrate is transported to the desalination water tank 9 for collection and recycling by the centrifugal pump, and the filter cloth follows the uniform and continuous rotation of the rotary drum after the discharge to realize the continuous operation of solid-liquid separation.

[0055] The process of drying and dehydrating the filter cake in step (3) includes: the solid material transported to the dryer 6 by the screw conveyor is continuously turned over under the driving of the stirring paddle and the scoop, and is fully contacted with the hot gas flow for drying and dehydration, while being gradually pushed by the screw conveying device to ensure the continuity of the operation process; there are four independent temperature control chambers in the dryer, and the yellow uranyl trioxide hydrate passes through the first drying treatment in the first drying chamber at 250℃, the second drying treatment in the second drying chamber at 320℃, the first dehydration treatment in the first dehydration chamber at 400℃, and the second dehydration treatment in the second dehydration chamber at 420℃ in sequence with the screw pushing, so that the drying process is accurately controlled by segmented temperature control, the controllability and uniformity of drying and dehydration in different stages are ensured, and finally the material with a porous structure is formed; the time of the first drying treatment is 5h, the time of the second drying treatment is 5h, the time of the first dehydration treatment is 5h, and the time of the second dehydration treatment is 5h; the dust-containing tail gas generated in the drying process is treated in sequence by the filter, the dust collector 7 and the condenser 8, the fine powder after filtration is returned to the dryer 6, and the purified waste gas is sent into the tail gas treatment pipeline by the high-pressure induced draft fan; after the solid material is dried and dehydrated, the brick-red amorphous UO3, i.e. UO3 after hydration activation, is generated.

[0056] Example 3 The present embodiment provides a continuous multi-stage hydration activation method for denitration UO3, which uses the continuous multi-stage hydration activation system for denitration UO3 in Example 1, and includes: Step (1), open the stirring device of the first stage hydration reactor 1, the second stage hydration reactor 2, the third stage hydration reactor 3 and the fourth stage hydration reactor 4, start the metering pump to add deionized water in the desalination water tank 9 into the first stage hydration reactor 1, open the vacuum suction device to suck the denitrated UO3 into the material bin at the top of the first stage hydration reactor 1, adjust the frequency control of the star feeder to control the feeding amount of the denitrated UO3, and the mass content of the denitrated UO3 in the mixed slurry is 60%; the temperature of the first stage hydration reactor 1 is 25℃, the temperature of the second stage hydration reactor is 30℃, the temperature of the third stage hydration reactor 3 is 30℃, and the temperature of the fourth stage hydration reactor 4 is 40℃, and the stirring speed of the stirring device in the first stage hydration reactor 1, the second stage hydration reactor 2, the third stage hydration reactor 3 and the fourth stage hydration reactor 4 is adjusted through the frequency converter to make the denitrated UO3 and the deionized water form a uniformly mixed slurry, the overflow port of the first stage hydration reactor 1 is opened after the first stage hydration reaction of the slurry in the first stage hydration reactor 1, the slurry is discharged into the second stage hydration reactor 2, the overflow port of the first stage hydration reactor 1 is closed, at the same time, the star feeder and the metering pump start to feed and react in the first stage hydration reactor 1, the overflow port of the second stage hydration reactor 2 is opened after the second stage hydration reaction in the second stage hydration reactor 2, the slurry is discharged into the third stage hydration reactor 3, the overflow port of the second stage hydration reactor 2 is closed after the slurry in the second stage hydration reactor 2 is discharged, and at the same time, the material discharged from the first stage hydration reactor 1 is accepted. By analogy, the slurry passes through the third stage hydration reactor 3 and the fourth stage hydration reactor 4 in turn until the reaction is completed. The time of the first stage hydration reaction is 0.5h, the time of the second stage hydration reaction is 1.5h, the time of the third stage hydration reaction is 2h, and the time of the fourth stage hydration reaction is 0.5h. The overflow port of the fourth stage hydration reactor 4 is opened, and after the slurry is discharged from the overflow port of the fourth stage hydration reactor 4, it is transported to the rotary drum vacuum filter 5 for solid-liquid separation by the screw conveyor.

[0057] Step (2), the process of filtering the slurry by the rotary drum vacuum filter 5 includes: feeding the slurry to be separated into the slurry tank of the rotary drum vacuum filter 5, the stirring device in the slurry tank stirs to avoid the settlement of the solid phase to reduce the filter cake resistance, the liquid phase penetrates through the filter cloth into the rotary drum filtrate channel under the action of the vacuum suction force, and the solid material is intercepted to form a uniform filter cake ≤1cm, when the rotary drum rotates to the discharge area, the scraper scrapes off the solid material which is transported to the dryer 6 by the screw conveyor, the filtrate is transported to the desalination water tank 9 by the centrifugal pump for collection and recycling, and the filter cloth follows the uniform and continuous rotation of the rotary drum to realize the continuous operation of solid-liquid separation.

[0058] The process of drying and dehydrating the filter cake in step (3) includes: the solid material transported to the dryer 6 by the screw conveyor continuously turns over under the driving of the stirring paddle and the scoop, and is fully contacted with the hot gas flow for drying and dehydrating, while gradually advancing by the screw conveying device to ensure the continuity of the operation process; there are four independent temperature control chambers in the dryer, and the yellow uranyl trioxide hydrate sequentially passes through the first drying treatment of the first drying chamber at 200℃, the second drying treatment of the second drying chamber at 370℃, the first dehydration treatment of the first dehydration chamber at 380℃ and the second dehydration treatment of the second dehydration chamber at 480℃, and the drying process is precisely controlled by the segmented temperature control to ensure the controllability and uniformity of the drying and dehydration in different stages, and finally the material with a porous structure is formed; the time of the first drying treatment is 2h, the time of the second drying treatment is 8h, the time of the first dehydration treatment is 5h, and the time of the second dehydration treatment is 2h; the dust-containing tail gas generated in the drying process is treated by a filter, a dust collector 7 and a condenser 8 in sequence, the fine powder after filtration is returned to the dryer 6, and the purified waste gas is sent into a tail gas treatment pipeline by a high-pressure induced draft fan; after the solid material is dried and dehydrated, the brick-red amorphous UO3, i.e. UO3 after hydration and activation, is generated.

[0059] The specific surface area and bulk density of the UO3 after hydration and activation obtained in Example 2-3 and the denitration UO3 raw material were detected, and the results are shown in Table 1.

[0060] Table 1

[0061] The denitration UO3 raw material is a coarse coated particle formed by the encapsulation and growth mechanism, the surface is a smooth and relatively hard and dense shell with few voids, so the specific surface area is very small, which is only 0.14m 2 / g, while the specific surface area of the UO3 after sufficient hydration and activation can reach 3.07m 2 / g, which is much larger than that of the denitration UO3 raw material, and the crystal structure of the material is changed after sufficient hydration and activation, as can be seen from Table 1, the material is changed from the original encapsulated and compacted particle to the loose and porous particle with high specific surface area, which greatly improves the activity and is beneficial to improve the efficiency of subsequent reduction and hydrofluorination conversion, and as can be seen from the comparison between the comparative examples and the examples, the four-stage hydration reaction and the drying and dehydration method with four independent temperature control chambers can improve the specific surface area of UO3 and reduce the bulk density.

[0062] The uniformity of the specific surface area of the UO3 after hydration and activation obtained in Example 2-3 was detected, and the detection method was: multi-point sampling at different detection points and repeated analysis and detection. The results are shown in Table 2.

[0063] Table 2

[0064] As can be seen from Table 2, the activated UO3 obtained by the denitration UO3 continuous multi-stage hydration activation system and method has good specific surface area uniformity.

[0065] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles described in the present application, can also be made several improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A continuous multi-stage hydration activation system for de-nitrating UO3, characterized in that, The system comprises: a first-stage hydration reactor (1), a second-stage hydration reactor (2), a third-stage hydration reactor (3), and a fourth-stage hydration reactor (4) connected in series; deionized water and denitration UO3 are delivered to the first-stage hydration reactor (1), the second-stage hydration reactor (2), the third-stage hydration reactor (3), and the fourth-stage hydration reactor (4) for reaction, and a reacted uranium trioxide hydrate slurry is obtained; a rotary drum vacuum filter (5) connected to the outlet of the fourth-stage hydration reactor (4) for filtering the uranium trioxide hydrate slurry to obtain solid materials; a dryer (6) connected to the outlet of the rotary drum vacuum filter (5) for drying and dehydrating the solid materials filtered by the rotary drum vacuum filter (5); a desalted water tank (9) connected to the first-stage hydration reactor (1) for supplying water to the first-stage hydration reactor (1); the dryer (6) comprises a first drying chamber, a second drying chamber, a first dehydration chamber, and a second dehydration chamber arranged in series along the material flow direction; the temperature of the first drying chamber is 200-280℃, the temperature of the second drying chamber is 290-370℃, the temperature of the first dehydration chamber is 380-420℃, and the temperature of the second dehydration chamber is 380-480℃.

2. The continuous multi-stage hydration activation system of de-NOx UO3 according to claim 1, characterized in that, The rotary drum filtrate channel of the rotary drum vacuum filter (5) is connected to the desalted water tank (9).

3. The continuous multi-stage hydration activation system of de-NOx UO3 according to claim 1, characterized in that, A dust remover (7) and a condenser (8) are arranged in series along the tail gas flow direction at the tail gas outlet of the dryer (6).

4. The continuous multi-stage hydration activation system of de-NOx UO3 according to claim 3, characterized in that, The condensate outlet of the condenser (8) is connected to the desalted water tank (9).

5. A continuous multi-stage hydration activation method of de-nitrated UO3, characterized in that, The method comprises: Step (A), water from the desalted water tank (9) is mixed with denitration UO3 in the first-stage hydration reactor (1) for first-stage hydration reaction; after the first-stage hydration reaction is completed, the slurry in the first-stage hydration reactor is transferred to the second-stage hydration reactor (2) for second-stage hydration reaction, and water and denitration UO3 are again supplied to the first-stage hydration reactor (1); after the second-stage hydration reaction is completed, the slurry in the second-stage hydration reactor (2) is transferred to the third-stage hydration reactor (3) for third-stage hydration reaction, and the slurry in the first-stage hydration reactor (1) is transferred to the second-stage hydration reactor (2), and water and denitration UO3 are again supplied to the first-stage hydration reactor (1); after the third-stage hydration reaction is completed, the slurry in the third-stage hydration reactor (3) is transferred to the fourth-stage hydration reactor (4) for fourth-stage hydration reaction, and the slurry in the first-stage hydration reactor (1) is transferred to the second-stage hydration reactor (2), the slurry in the second-stage hydration reactor (2) is transferred to the third-stage hydration reactor (3), and water and denitration UO3 are again supplied to the first-stage hydration reactor (1); and the material is continuously subjected to four-stage hydration reactions in sequence. In step (B), the slurry discharged from the fourth stage of the hydration reactor (4) is filtered in a rotary drum vacuum filter (5), and the filter cake is sequentially subjected to first drying, second drying, first dewatering and second dewatering in the first drying chamber, the second drying chamber, the first dewatering chamber and the second dewatering chamber of the dryer (6) to obtain the hydrated and activated UO3.

6. The continuous multi-stage hydration activation method of de-NOx U03 according to claim 5, characterized in that, In step (B), the filtrate obtained by filtration is circulated in the desalted water tank (9) through the rotary drum filtrate channel.

7. The continuous multi-stage hydration activation method of de-NOx U03 according to claim 5, characterized in that, In step (B), the water vapor tail gas formed in the drying and dewatering process is subjected to dust removal in the dust remover (7) and then is condensed in the condenser (8), and the condensed water is discharged into the desalted water tank (9) for recycling.

8. The continuous multi-stage hydration activation method of de-NOx U03 according to claim 5, characterized in that, In the first stage of the hydration reactor (1), the mass content of the denitration UO3 in the mixed slurry formed by water and the denitration UO3 is 40-60%.

9. The continuous multi-stage hydration activation method of de-NOx U03 according to claim 5, characterized in that, The reaction temperature of the first stage of the hydration reaction, the second stage of the hydration reaction, the third stage of the hydration reaction and the fourth stage of the hydration reaction is independently 25-40℃, and the reaction time is independently 0.5-2h.

10. The continuous multi-stage hydration activation method of de-NOx U03 according to claim 5, characterized in that, The time of the first drying, the second drying, the first dewatering and the second dewatering is independently 2-8h.

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