Uranium ore concentrate continuous dissolving device and method

Abstract

The invention relates to the field of uranium purification, in particular to a uranium ore concentrate continuous dissolving device and method. The device comprises a dissolving barrel, the outermost layer is a water bath jacket, the water bath jacket is not communicated with a middle barrel, an inner barrel is placed on an integrated structure of the water bath jacket and the middle barrel, and the bottom of the inner barrel is communicated with the middle barrel; a top cover is arranged at the top of the dissolving barrel, and two feeding holes are formed in the top cover; the stirring shaft and the thermometer are inserted into the inner-layer barrel from the top cover; the stirring shaft and the thermometer are inserted into the inner-layer barrel from the top cover; the middle of the middle cylinder is provided with a dissolved material liquid discharge port, and the bottom is provided with a slag discharge port; the stirring shaft is connected with at least three layers of stirring paddles, the uppermost layer is a hinge turbine paddle, the middle layer is a disc turbine paddle, and the lowermost layer is an anchor paddle. The method comprises the following steps: grinding uranium ore concentrate and water; thickening the obtained grinding slurry; carrying out continuous dissolution; and carrying out two times of centrifugal separation on the dissolved slurry. According to the invention, continuous dissolution of the uranium ore concentrate is realized, and the dissolution efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of uranium purification, and in particular to a device and method for continuous dissolution of uranium ore concentrate. Background Art

[0002] Uranium purification and conversion includes the processes of dissolution of uranium ore concentrate - extraction and purification of dissolving liquid - concentration and denitration - hydration and activation - reduction - hydrofluorination - fluorination - condensation and liquefaction - product reception, etc. It is an important part of my country's nuclear fuel cycle. The dissolution of uranium ore concentrate is the primary process of uranium purification and conversion, and its importance can be seen.

[0003] At present, the dissolution process of uranium ore concentrate in industrial production is intermittent dissolution, and the main equipment is a tank container, which has the advantages of simple device structure and easy operation, but also has the disadvantages of low dissolution efficiency and large equipment volume. Moreover, after the batch addition of materials, the harmful waste gas generated is also batch output, and there are large fluctuations in the instantaneous generation and gas concentration. Subsequent continuous and stable treatment is very difficult. If the treatment effect of the maximum generation and concentration of waste gas is guaranteed, the volume of the treatment equipment must be very large, and the investment will also increase significantly.

[0004] In addition, most systems are now manually operated, requiring many production personnel, low labor productivity, and the working environment is often not ideal due to the involvement of radioactive dust. In comparison, continuous dissolution devices have gradually become the future development trend due to their advantages such as relatively constant composition of the dissolving liquid, low labor intensity of operators, easy automatic control, and conducive to continuous and stable operation.

[0005] In general, there are relatively few studies on the continuous dissolution of uranium ore concentrates, and there is an even greater lack of corresponding industrial scale-up designs, which to a certain extent restricts the overall improvement of my country's uranium purification and conversion capacity. There is an urgent need to propose a continuous dissolution system with a simple structure, good performance and stable operation. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a uranium ore concentrate continuous dissolution device and method, which can improve the dissolution efficiency while improving the uranium ore concentrate dissolution operation environment.

[0007] The present invention provides a uranium ore concentrate continuous dissolution device, comprising:

[0008] The dissolving cylinder is a three-layer structure, the outermost layer is a water bath jacket, the water bath jacket is not connected to the middle cylinder, the inner cylinder is placed on the integrated structure of the water bath jacket and the middle cylinder, and the bottom of the inner cylinder is connected to the middle cylinder;

[0009] The top of the dissolving cylinder is a top cover, which is provided with a uranium concentrate feed port and a nitric acid solution feed port; the stirring shaft and the thermometer are inserted into the inner cylinder through the top cover;

[0010] The bottom of the water bath jacket is provided with a heat medium inlet, and the upper part is provided with a heat medium outlet;

[0011] The middle part of the intermediate cylinder is provided with a dissolving liquid outlet, and the bottom is provided with a slag discharge port and an emergency liquid outlet;

[0012] At least three layers of stirring paddles are connected to the stirring shaft, the top layer is a folding blade turbine paddle, the middle layer is a disc turbine paddle, and the bottom layer is an anchor paddle.

[0013] Preferably, the inner cylinder is shorter than the middle cylinder.

[0014] Preferably, when the number of layers of the stirring impellers is more than three, the middle layers are all disc turbine impellers.

[0015] Preferably, the height-to-diameter ratio of the dissolving cylinder is 3 to 7:1, and the spacing between the stirring paddles of each layer is 1 to 3 times the inner diameter of the inner cylinder.

[0016] Preferably, an emergency liquid outlet is provided on the side wall of the slag discharge port.

[0017] The present invention provides a method for continuous dissolution of uranium ore concentrate, comprising the following steps:

[0018] Step 1: Grind the uranium ore concentrate and water;

[0019] Step 2: The obtained grinding slurry is thickened, and the thickened overflow is returned to step 1 for further grinding;

[0020] Step 3: Calculate the amount and speed of adding uranium ore concentrate, acid and water according to the required uranium concentration and acidity of the dissolving solution, and continuously add the uranium ore concentrate continuous dissolving device described in the above technical solution at the calculated speed to carry out continuous dissolution;

[0021] Step 4: separating the dissolved slurry to obtain separation slurry and separation coarse slag;

[0022] The separated coarse residue is washed with countercurrent water, and the final pH value of the water washing reaches 6-8.5; the washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned to the washing cycle;

[0023] Step 5: The separated slurry obtained in the previous step is centrifuged again, and the separated coarse residue is countercurrent washed with acid solution, and the first washing water is returned to step 3, and the other washing water is returned as washing liquid for recycling, and the washed residue is safely disposed of;

[0024] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0025] Preferably, in the step 1, water is added in a spray form, and the mass ratio of water to uranium ore concentrate is 3 to 10:1.

[0026] Preferably, in the step 1, the grinding time is not less than 10 minutes, and the grinding particle size of the uranium ore concentrate of -100 mesh accounts for 90%.

[0027] Preferably, in step 2, thickening is performed in a thickening device, and solid particles gather at the bottom of the thickening device to form a thickening underflow. A rotating rake is provided at the bottom of the thickening device to prevent the underflow from settling and being unable to be discharged by slowly rotating it.

[0028] Preferably, in the step 2, the grinding slurry stays in the thickening device for no less than 15 minutes, and the solid content of the thickening underflow is no less than 25%.

[0029] Preferably, in step three, the acid is one or more of nitric acid, sulfuric acid and hydrochloric acid. If there is no nitric acid in the acid, an oxidant is added at the same time, and the oxidant is hydrogen peroxide or ozone.

[0030] Preferably, in step 4, the separation factor of the centrifugal separation device is 1500-2500, and the separation residence time is not less than 2 minutes.

[0031] Preferably, in step 5, during centrifugal separation, the separation factor is greater than 2500, the separation residence time is not less than 3 minutes, and the turbidity of the solution after separation is not higher than 50 NTU.

[0032] Preferably, in step 3 and step 5, the washing acid is of the same type as the dissolving acid, and the acid concentration is above 5 g / L.

[0033] Preferably, in step three, the dissolution temperature is 50-80°C, the dissolution residence time is 30-90 min, and the overflow speed of the slurry in the middle cylinder is not less than 10 cm / min.

[0034] Compared with the prior art, the method for continuous dissolution of uranium ore concentrate of the present invention can realize continuous, stable and effective dissolution of uranium ore concentrate, greatly reduce the labor intensity, improve the working environment, and the uranium concentration of the dissolved liquid can reach 400g / L; after the dissolved slurry is centrifuged, a clear liquid with a turbidity of less than 50NTU can be obtained, which meets the processing requirements of subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram showing the structure of a continuous dissolution device for uranium ore concentrate;

[0036] Figure 2 A flow chart showing a method for continuous dissolution of uranium ore concentrate;

[0037] In the figure,

[0038] 1. Uranium concentrate feed port; 2. Nitric acid solution feed port; 3. Top cover; 4. Thermometer; 5. Intermediate cylinder; 6. Inner cylinder; 7. Water bath jacket; 8. Heating medium inlet; 9. Heating medium outlet; 10. Dissolved liquid outlet; 11. Stirring shaft; 12. Folding blade turbine propeller; 13. Disc turbine propeller; 14. Anchor propeller; 15. Slag discharge port; 16. Emergency discharge port. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0040] The embodiment of the present invention discloses a uranium ore concentrate continuous dissolution device, such as Figure 1 As shown, including:

[0041] The dissolving cylinder is a three-layer structure, the outermost layer is a water bath jacket 7, the water bath jacket 7 is not connected to the middle cylinder 5, the inner cylinder 6 is placed on the integral structure of the water bath jacket 7 and the middle cylinder 5, and the bottom of the inner cylinder 6 is connected to the middle cylinder 5;

[0042] Preferably, the inner cylinder 6 is shorter than the middle cylinder 5, so the middle cylinder 5 and the inner cylinder 6 are connected at the bottom to form a dissolution reaction space for the uranium ore concentrate;

[0043] The top of the dissolving cylinder is a top cover 3, on which a uranium concentrate feed port 4 and a nitric acid solution feed port 2 are arranged; a stirring shaft 11 and a thermometer 4 are inserted into the inner cylinder 6 through the top cover;

[0044] The bottom of the water bath jacket 7 is provided with a heat medium inlet 8, and the upper part is provided with a heat medium outlet 9;

[0045] The middle of the intermediate cylinder 5 is provided with a dissolving liquid outlet 10, and the bottom is provided with a slag discharge port 15 and an emergency liquid outlet 16;

[0046] An emergency liquid outlet 16 is provided on the side wall of the slag discharge port 15;

[0047] The stirring shaft 11 is connected to at least three layers of stirring paddles, the top layer is a folding blade turbine paddle 12 , the middle layer is a disc turbine paddle 13 , and the bottom layer is an anchor paddle 14 .

[0048] The uppermost folding-blade turbine impeller 12 is used to quickly disperse and mix the uranium concentrate; the middle-layer disc turbine impeller 13 maintains the dissolution gradient and avoids mixed flow; the lowermost anchor impeller 14 forms a horizontal flow to ensure that the liquid in the middle cylinder of the dissolving device overflows stably from the bottom to the top; the bottom flow of uranium ore concentrate is added together with acid and water from the upper part of the inner cylinder of the dissolving device, and then overflows from the overflow port at the upper part of the middle cylinder of the dissolving device, forming a "U"-shaped route.

[0049] When the number of layers of the stirring impellers is more than three, the middle layers are all disc turbine impellers.

[0050] The height-to-diameter ratio of the dissolving cylinder is 3-7:1, and the spacing between the stirring paddles of each layer is 1-3 times the inner diameter of the inner cylinder.

[0051] The embodiments of the present invention also disclose a method for continuous dissolution of uranium ore concentrate, such as Figure 2 As shown, the following steps are included:

[0052] Step 1: Grind the uranium ore concentrate and water;

[0053] Step 2: The obtained grinding slurry is thickened, and the thickened overflow is returned to step 1 for further grinding;

[0054] Step 3: Calculate the amount and speed of adding uranium ore concentrate, acid and water according to the required uranium concentration and acidity of the dissolving solution, and continuously add the uranium ore concentrate continuous dissolution device according to any one of claims 1 to 5 at the calculated speed to carry out continuous dissolution;

[0055] Step 4: separating the dissolved slurry to obtain separation slurry and separation coarse slag;

[0056] The separated coarse residue is washed with countercurrent water, and the final pH value of the water washing reaches 6-8.5; the washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned to the washing cycle;

[0057] Step 5: The separated slurry obtained in the previous step is centrifuged again, and the separated coarse residue is countercurrent washed with acid solution, and the first washing water is returned to the dissolution process, and the other washing water is returned as washing liquid for recycling, and the washed residue is safely disposed of;

[0058] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0059] The following describes in detail the method for continuous dissolution of uranium ore concentrate according to the steps of the present invention:

[0060] Step 1: Grind the uranium ore concentrate and water;

[0061] Water is added in a spray form to prevent the uranium concentrate dust from spilling out. The mass ratio of water to uranium ore concentrate is 3 to 10:1 to ensure that the grinding material has good fluidity.

[0062] The grinding of the uranium ore concentrate in this step is carried out in a grinding device, which includes but is not limited to a ball mill, a rod mill, and the like.

[0063] The grinding time is not less than 10 minutes, and the grinding particle size of the uranium ore concentrate is -100 mesh accounting for 90%.

[0064] Step 2: The obtained grinding slurry is thickened, and the thickened overflow is returned to step 1 for further grinding;

[0065] This step is performed in a thickening device, where solid particles gather at the bottom of the thickening device to form a thick underflow, which can be added to the dissolving device by a conveying device; the thick overflow has a very low solid content and is then returned to the grinding step 1;

[0066] A rotating rake is provided at the bottom of the thickening device, which rotates slowly to prevent the bottom flow from settling and being unable to be discharged.

[0067] The grinding slurry stays in the thickening equipment for no less than 15 minutes, and the solid content of the thickening underflow is no less than 25%.

[0068] The conveying device of the underflow includes but is not limited to a mud pump and a slurry pump.

[0069] Step 3: Calculate the amount and speed of adding uranium ore concentrate, acid and water according to the required uranium concentration and acidity of the dissolving solution, and continuously add the uranium ore concentrate continuous dissolving device described in the above technical solution at the calculated speed to carry out continuous dissolution;

[0070] A heating medium is introduced into the water bath jacket of the dissolving device to maintain the dissolving reaction temperature.

[0071] The acid is one or more of nitric acid, sulfuric acid and hydrochloric acid. If there is no nitric acid in the acid, an oxidant is added at the same time. The oxidant is hydrogen peroxide or ozone.

[0072] The dissolution temperature is 50-80°C, the dissolution residence time is 30-90 minutes, and the overflow speed of the slurry in the middle cylinder is not less than 10 cm / min.

[0073] Step 4: separating the dissolved slurry to obtain separation slurry and separation coarse slag;

[0074] The separated coarse residue is washed with countercurrent water, and the final pH value of the water washing reaches 6-8.5; the washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned to the washing cycle;

[0075] The step 4 is the initial centrifugal separation of the dissolved slurry.

[0076] Preferably, the dissolved slurry is aged for 6 to 8 hours before centrifugation.

[0077] The separation is carried out by a centrifugal separation device, the separation factor of the centrifugal separation device is 1500-2500, and the separation residence time is not less than 2 minutes.

[0078] The centrifugal separation device includes but is not limited to a horizontal centrifugal separator.

[0079] Step 5: The separated slurry obtained in the previous step is centrifuged again, and the separated coarse residue is countercurrent washed with acid solution, and the first washing water is returned to the dissolution process, and the other washing water is returned as washing liquid for recycling, and the washed residue is safely disposed of;

[0080] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0081] The step 5 is to separate the separated slurry obtained in the step 4 again, which can be transported by a pump to a centrifugal separation device with a high separation factor.

[0082] Preferably, during centrifugal separation, the separation factor is greater than 2500, the separation residence time is not less than 3 minutes, and the turbidity of the solution after separation is not higher than 50 NTU.

[0083] The separated coarse residue is counter-washed with acid solution for no less than 3 times, and the water from the first wash is returned to the dissolution process, i.e., to step 3, and the other wash water is returned as washing liquid for recycling, and the washed residue is safely disposed of in accordance with the standards;

[0084] The type of acid used for washing is the same as that for dissolving, and the concentration of the acid solution is above 5g / L.

[0085] The centrifugal separation device includes, but is not limited to, a horizontal centrifuge.

[0086] The present invention aims at the problems of large fluctuations in material concentration and waste generated in batch dissolution of uranium ore concentrate, large number of production personnel, low labor productivity, etc., and develops a continuous dissolution system and method, which realizes rapid dispersion of uranium ore concentrate while ensuring the residence time of dissolved materials, avoiding the escape of undissolved uranium ore concentrate dust, and finally realizes continuous, stable and effective dissolution of uranium ore concentrate, greatly reducing manual labor intensity and improving the working environment. The uranium concentration of the dissolved liquid can reach 400g / L, and the dissolved slurry can be centrifuged to obtain a clear liquid with a turbidity of less than 50NTU, which can meet the processing requirements of subsequent processes.

[0087] In order to further understand the present invention, the uranium ore concentrate continuous dissolution device and method provided by the present invention are described in detail below in conjunction with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0088] Embodiments 1 to 5

[0089] Step 1: Grinding of Uranium Ore Concentrate

[0090] Add industrial uranium ore concentrate and water to the grinding equipment together, and add water in a spray form to prevent uranium concentrate dust from overflowing; the grinding time is not less than 10 minutes, and the grinding particle size of uranium ore concentrate is -100 mesh, accounting for 90%; the mass ratio of water to uranium ore concentrate is 3 to 10:1 to ensure that the grinding material has good fluidity;

[0091] Step 2: Grinding slurry is dense

[0092] The grinding slurry obtained in step 1 is discharged into the thickening device, and the solid particles gather at the bottom of the thickening device to form a thick bottom flow. The thick bottom flow is added to the dissolution device by a conveying device; the thick overflow has a very low solid content and returns to the grinding process in step 1. A rotating rake is provided at the bottom of the thickening device, which rotates slowly to prevent the bottom flow from settling and being unable to be discharged. The grinding slurry stays in the thickening device for no less than 15 minutes, and the solid content of the thick bottom flow is not less than 25%. The conveying device of the bottom flow includes but is not limited to a mud pump and a slurry pump.

[0093] Step 3: Dissolution of uranium ore concentrate

[0094] According to the required uranium concentration and acidity of the dissolving solution, the amount and speed of uranium concentrate, acid and water are calculated. The uranium concentrate is added continuously by the mud pump at a certain speed, and the acid and water are added continuously by the metering pump at the calculated speed. The heating medium is introduced into the outer jacket of the dissolving device to maintain the dissolving reaction temperature. The height-to-diameter ratio of the dissolving device is 3:1-7:1, the spacing between each layer of stirring paddles is 1 to 3 times the inner diameter of the central tube, the dissolving temperature is 50 to 80°C, the dissolving residence time is 30 to 90 minutes, and the overflow speed of the slurry in the second layer of the dissolving tube is not less than 10 cm / min. The acid type can be one of nitric acid, sulfuric acid, and hydrochloric acid, used alone or in combination of two or more. When the dissolving acid does not contain nitric acid, an oxidant needs to be added, and the oxidant is hydrogen peroxide or ozone.

[0095] Step 4: Initial centrifugation of dissolved slurry

[0096] The dissolved slurry enters the storage barrel, and after aging in the storage barrel for 6 hours, it is pumped to the centrifugal separation device for separation to obtain separation slurry and separation coarse slag;

[0097] The separated coarse residue is washed with countercurrent water for no less than 3 times, and the final pH value of the water washing reaches 6-8.5. The washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned as washing liquid for recycling;

[0098] The separation factor of the centrifugal separation device is 1500, and the separation residence time is 2 minutes. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0099] Step 5: Separate the slurry and centrifuge again

[0100] The separated slurry obtained in step 4 enters a storage tank and is transported by a pump to a high separation factor centrifugal separation device for further separation;

[0101] The separated coarse residue is washed with acid solution for no less than 3 times in countercurrent, and the water from the first wash is returned to the dissolution process, and the other wash water is returned for recycling as washing liquid, and the washed residue is safely disposed of in accordance with the corresponding standards;

[0102] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0103] The separation factor of the high separation factor centrifugal separation device is 2500 or more, the separation residence time is not less than 3 minutes, and the turbidity of the separated solution is not higher than 50NTU; the type of washing acid is the same as that of dissolving acid, and the acid concentration is 5g / L or more. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0104] The present invention is further described below in conjunction with the accompanying drawings and examples. The process conditions and results are shown in Table 1.

[0105] Table 1 Test conditions and results

[0106]

[0107] Example 6

[0108] Step 1: Grinding of Uranium Ore Concentrate

[0109] Industrial uranium ore concentrate and water are added to the grinding equipment together. Water is added in a spray form to prevent uranium concentrate dust from overflowing. The grinding time is 10 minutes, and the grinding particle size of uranium ore concentrate is -100 mesh, accounting for 90%. The mass ratio of water to uranium ore concentrate is 3:1 to ensure that the grinding material has good fluidity.

[0110] Step 2: Grinding slurry is dense

[0111] The grinding slurry obtained in step 1 is discharged into the thickening device, and the solid particles gather at the bottom of the thickening device to form a thick bottom flow. The thick bottom flow is added to the dissolving device by a conveying device; the thick overflow has a very low solid content and returns to the grinding process in step 1. A rotating rake is provided at the bottom of the thickening device, which rotates slowly to prevent the bottom flow from settling and being unable to be discharged. The grinding slurry stays in the thickening device for 15 minutes, and the thick bottom flow has a solid content of 25%. The conveying device of the bottom flow includes but is not limited to a mud pump and a slurry pump.

[0112] Step 3: Dissolution of uranium ore concentrate

[0113] According to the required uranium concentration and acidity of the solution, the amount and speed of uranium concentrate, acid and water are calculated. The uranium concentrate is added continuously by the mud pump at a certain speed, and the acid and water are added continuously by the metering pump at the calculated speed. The heating medium is introduced into the outer jacket of the dissolving device to maintain the dissolving reaction temperature. The height-to-diameter ratio of the dissolving device is 3:1, the spacing between each layer of stirring paddles is 3 times the inner diameter of the central tube, the dissolving temperature is 50℃, the dissolving residence time is 30min, and the slurry overflow speed of the second layer dissolving tube is 10cm / min. The concentration of the nitric acid aqueous solution is 6mol / L.

[0114] Step 4: Initial centrifugation of dissolved slurry

[0115] The dissolved slurry enters the storage barrel, and after aging in the storage barrel for 6 hours, it is pumped to the centrifugal separation device for separation to obtain separation slurry and separation coarse slag;

[0116] The separated coarse residue is washed with countercurrent water for 3 times, and the final pH value of the water washing reaches 6. The washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned as washing liquid for recycling;

[0117] The separation factor of the centrifugal separation device is 1500, and the separation residence time is 2 minutes. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0118] Step 5: Separate the slurry and centrifuge again

[0119] The separated slurry obtained in step 4 enters a storage tank and is transported by a pump to a high separation factor centrifugal separation device for further separation;

[0120] The separated coarse residue is washed with acid solution for no less than 3 times in countercurrent, and the water from the first wash is returned to the dissolution process, and the other wash water is returned for recycling as washing liquid, and the washed residue is safely disposed of in accordance with the corresponding standards;

[0121] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0122] The separation factor of the high separation factor centrifugal separation device is 2500, the separation residence time is 4 minutes, and the turbidity of the separated solution is not higher than 36NTU; nitric acid washing, the acid concentration is above 5g / L. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0123] Example 7

[0124] Step 1: Grinding of Uranium Ore Concentrate

[0125] Industrial uranium ore concentrate and water are added to the grinding equipment together. Water is added in a spray form to prevent uranium concentrate dust from overflowing. The grinding time is 12 minutes, and the grinding particle size of uranium ore concentrate is -100 mesh, accounting for 95%. The mass ratio of water to uranium ore concentrate is 5:1 to ensure that the grinding material has good fluidity.

[0126] Grinding equipment includes but is not limited to ball mills, rod mills, etc.

[0127] Step 2: Grinding slurry is dense

[0128] The grinding slurry obtained in step 1 is discharged into the thickening device, and the solid particles gather at the bottom of the thickening device to form a thick bottom flow. The thick bottom flow is added to the dissolving device by a conveying device; the thick overflow has a very low solid content and returns to the grinding process in step 1. A rotating rake is provided at the bottom of the thickening device, which rotates slowly to prevent the bottom flow from settling and being unable to be discharged. The grinding slurry stays in the thickening device for 17 minutes, and the thick bottom flow has a solid content of 27%. The conveying device of the bottom flow includes but is not limited to a mud pump and a slurry pump.

[0129] Step 3: Dissolution of uranium ore concentrate

[0130] According to the required uranium concentration and acidity of the solution, the amount and speed of uranium concentrate, acid and water are calculated. The uranium concentrate is added continuously by the slurry pump at a certain speed, and the acid and water are added continuously by the metering pump at the calculated speed. The heating medium is introduced into the outer jacket of the dissolving device to maintain the dissolving reaction temperature. The height-to-diameter ratio of the dissolving device is 5:1, the spacing between each layer of stirring paddles is twice the inner diameter of the central tube, the dissolving temperature is 65°C, the dissolving residence time is 50min, and the overflow speed of the slurry in the second layer dissolving tube is 10cm / min. The concentration of sulfuric acid solution is 3mol / L, and the concentration of hydrogen peroxide is 0.5mol / L.

[0131] Step 4: Initial centrifugation of dissolved slurry

[0132] The dissolved slurry enters the storage barrel, and after aging in the storage barrel for 6 hours, it is pumped to the centrifugal separation device for separation to obtain separation slurry and separation coarse slag;

[0133] The separated coarse residue is washed with countercurrent water for 3 times, and the final pH value of the water washing reaches 7.5. The washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned as washing liquid for recycling;

[0134] The separation factor of the centrifugal separation device is 2100, and the separation residence time is 2 minutes. The centrifugal separation device includes but is not limited to a horizontal centrifugal separator.

[0135] Step 5: Separate the slurry and centrifuge again

[0136] The separated slurry obtained in step 4 enters a storage tank and is transported by a pump to a high separation factor centrifugal separation device for further separation;

[0137] The separated coarse residue is washed with acid solution for no less than 3 times in countercurrent, and the water from the first wash is returned to the dissolution process, and the other wash water is returned for recycling as washing liquid, and the washed residue is safely disposed of in accordance with the corresponding standards;

[0138] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0139] The separation factor of the high separation factor centrifugal separation device is 3000 or more, the separation residence time is 4 minutes, the turbidity of the separated solution is 35 NTU; the sulfuric acid washing, the acid concentration is 5g / L or more. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0140] Example 8

[0141] Step 1: Grinding of Uranium Ore Concentrate

[0142] Industrial uranium ore concentrate and water are added to the grinding equipment together. Water is added in a spray form to prevent uranium concentrate dust from overflowing. The grinding time is 15 minutes, and the grinding particle size of uranium ore concentrate is -100 mesh, accounting for 97%. The mass ratio of water to uranium ore concentrate is 10:1 to ensure that the grinding material has good fluidity.

[0143] Grinding equipment includes but is not limited to ball mills, rod mills, etc.

[0144] Step 2: Grinding slurry is dense

[0145] The grinding slurry obtained in step 1 is discharged into the thickening device, and the solid particles gather at the bottom of the thickening device to form a thick underflow. The thick underflow is added to the dissolving device by a conveying device; the thick overflow has a very low solid content and returns to the grinding process in step 1. A rotating rake is provided at the bottom of the thickening device, which rotates slowly to prevent the underflow from settling and being unable to be discharged. The grinding slurry stays in the thickening device for 20 minutes, and the thick underflow has a solid content of 28%. The conveying device of the underflow includes but is not limited to a mud pump and a slurry pump.

[0146] Step 3: Dissolution of uranium ore concentrate

[0147] According to the required uranium concentration and acidity of the solution, the amount and speed of uranium concentrate, acid and water are calculated. The uranium concentrate is added continuously by the slurry pump at a certain speed, and the acid and water are added continuously by the metering pump at the calculated speed. The heating medium is introduced into the outer jacket of the dissolving device to maintain the dissolving reaction temperature. The height-to-diameter ratio of the dissolving device is 7:1, the spacing between each layer of stirring paddles is 1 times the inner diameter of the central tube, the dissolving temperature is 80℃, the dissolving residence time is 90min, and the overflow speed of the slurry in the second layer dissolving tube is 11cm / min. Hydrochloric acid + hydrogen peroxide aqueous solution, hydrochloric acid concentration: 4mol / L, hydrogen peroxide concentration: 0.5mol / L.

[0148] Step 4: Initial centrifugation of dissolved slurry

[0149] The dissolved slurry enters the storage barrel, and after aging in the storage barrel for 6 hours, it is pumped to the centrifugal separation device for separation to obtain separation slurry and separation coarse slag;

[0150] The separated coarse residue is washed with countercurrent water for 3 times, and the final pH value of the water washing reaches 8.5. The washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned as washing liquid for recycling;

[0151] The separation factor of the centrifugal separation device is 2500, and the separation residence time is 2 minutes. The centrifugal separation device includes but is not limited to a horizontal centrifugal separator.

[0152] Step 5: Separate the slurry and centrifuge again

[0153] The separated slurry obtained in step 4 enters a storage tank and is transported by a pump to a high separation factor centrifugal separation device for further separation;

[0154] The separated coarse residue is washed three times in countercurrent with acid solution, one wash water is returned to the dissolution process, and the other wash water is returned to be recycled as washing liquid, and the washed residue is safely disposed of in accordance with the corresponding standards;

[0155] The separated solution is used as raw material for the next step of uranium purification and conversion.

[0156] The separation factor of the high separation factor centrifugal separation device is 3500, the separation residence time is 3 minutes, and the turbidity of the separated solution is 30NTU; the hydrochloric acid washing, the acid concentration is 5g / L or more. The centrifugal separation device includes but is not limited to a horizontal centrifuge.

[0157] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0158] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A continuous dissolution device for uranium ore concentrate, characterized in that: include: The dissolving cylinder is a three-layer structure, the outermost layer is a water bath jacket, the water bath jacket is not connected to the middle cylinder, the inner cylinder is placed on the integrated structure of the water bath jacket and the middle cylinder, and the bottom of the inner cylinder is connected to the middle cylinder; The top of the dissolving cylinder is a top cover, which is provided with a uranium concentrate feed port and a nitric acid solution feed port; the stirring shaft and the thermometer are inserted into the inner cylinder through the top cover; The bottom of the water bath jacket is provided with a heat medium inlet, and the upper part is provided with a heat medium outlet; The middle part of the intermediate cylinder is provided with a dissolving liquid outlet, and the bottom is provided with a slag discharge port and an emergency liquid outlet; At least three layers of stirring paddles are connected to the stirring shaft, the top layer is a folding blade turbine paddle, the middle layer is a disc turbine paddle, and the bottom layer is an anchor paddle.

2. The uranium ore concentrate continuous dissolution device according to claim 1, characterized in that: The inner cylinder is shorter than the middle cylinder.

3. The uranium ore concentrate continuous dissolution device according to claim 1, characterized in that: When the number of layers of the stirring impellers is more than three, the middle layers are all disc turbine impellers.

4. The uranium ore concentrate continuous dissolution device according to claim 1, characterized in that: The height-to-diameter ratio of the dissolving cylinder is 3-7:1, and the spacing between the stirring paddles of each layer is 1-3 times the inner diameter of the inner cylinder.

5. The uranium ore concentrate continuous dissolution device according to claim 1, characterized in that: An emergency liquid outlet is arranged on the side wall of the slag discharge port.

6. A method for continuous dissolution of uranium ore concentrate, characterized in that: The following steps are involved: Step 1: Grind the uranium ore concentrate and water; Step 2: The obtained grinding slurry is thickened, and the thickened overflow is returned to step 1 for further grinding; Step 3: Calculate the amount and speed of adding uranium ore concentrate, acid and water according to the required uranium concentration and acidity of the dissolving solution, and continuously add the uranium ore concentrate continuous dissolution device according to any one of claims 1 to 5 at the calculated speed to carry out continuous dissolution; Step 4: separating the dissolved slurry to obtain separation slurry and separation coarse slag; The separated coarse residue is washed with countercurrent water, and the final pH value of the water washing reaches 6-8.5; the washed residue is returned to the grinding process, the first washing water is returned to the dissolving process, and the other washing water is returned to the washing cycle; Step 5: The separated slurry obtained in the previous step is centrifuged again, and the separated coarse residue is countercurrent washed with acid solution, and the first washing water is returned to step 3, and the other washing water is returned as washing liquid for recycling, and the washed residue is safely disposed of; The separated solution is used as raw material for the next step of uranium purification and conversion.

7. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step 1, water is added in a spray form, and the mass ratio of water to uranium ore concentrate is 3 to 10:

1.

8. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step 1, the grinding time is not less than 10 minutes, and the grinding particle size of the uranium ore concentrate of -100 mesh accounts for 90%.

9. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step 2, thickening is performed in a thickening device, and solid particles gather at the bottom of the thickening device to form a thickening underflow. A rotating rake is provided at the bottom of the thickening device to prevent the underflow from settling and being unable to be discharged by slowly rotating.

10. The method for continuous dissolution of uranium ore concentrate according to claim 9, characterized in that: In the step 2, the grinding slurry stays in the thickening device for no less than 15 minutes, and the solid content of the thickening underflow is no less than 25%.

11. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step 3, the acid is one or more of nitric acid, sulfuric acid and hydrochloric acid. If there is no nitric acid in the acid, an oxidant is added at the same time, and the oxidant is hydrogen peroxide or ozone.

12. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step 4, the separation factor of the centrifugal separation device is 1500-2500, and the separation residence time is not less than 2 minutes.

13. The method for continuous dissolution of uranium ore concentrate according to claim 12, characterized in that: In step 5, during centrifugal separation, the separation factor is greater than 2500, the separation residence time is not less than 3 minutes, and the turbidity of the solution after separation is not higher than 50NTU.

14. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In step 3 and step 5, the type of washing acid is the same as that of dissolving acid, and the concentration of the acid solution is above 5 g / L.

15. The method for continuous dissolution of uranium ore concentrate according to claim 6, characterized in that: In the step three, the dissolution temperature is 50-80°C, the dissolution residence time is 30-90 minutes, and the overflow speed of the slurry in the middle cylinder is not less than 10 cm / min.

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