A method and device for purifying silicon micropowder by removing uranium

Abstract

The present invention belongs to the technical field of silicon micropowder processing and manufacturing, and specifically relates to a method and device for removing uranium and purifying silicon micropowder. The method for removing uranium and purifying silicon micropowder includes a slurry preparation process, a uranium removal process, and a slurry drying process. Both the first adsorption orifice plate and the second adsorption orifice plate are graphene oxide sol honeycomb ceramic plates. This method, in combination with the device, realizes the integrated operation of uranium adsorption and drying of silicon micropowder, with a simple process and being suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon micropowder processing and manufacturing, and particularly relates to a method and device for removing uranium and purifying silicon micropowder. Background Art

[0002] With the development of large-scale and ultra-large-scale integrated circuit packaging technology, spherical silicon micropowder has been widely used in integrated circuit packaging due to its excellent fluidity and low thermal expansion coefficient. However, current silicon micropowder generally contains uranium. In order to avoid errors caused by radioactive elements in semiconductor devices, the preparation of high-purity and low-radioactive spherical silicon micropowder with a uranium (U) content (mass fraction) of less than 1×10 -9 is still an urgent problem to be solved.

[0003] Currently, there are mainly two methods for producing high-purity and low-radioactive spherical silicon micropowder. One is to spheroidize and cool natural high-purity quartz or high-purity silicon micropowder by physical methods such as flame melting method and plasma method to obtain the product. This method has a simple process, but requires high purity of silicon micropowder and has poor uranium removal effect. The other is to use chemical methods such as microemulsion method, sol-gel method, etc. After emulsifying, concentrating and granulating high-purity organosilane or water glass, high-purity silicon micropowder is obtained, and then the roasting and spheroidization processes are carried out to obtain high-purity and low-radioactive spherical silicon micropowder. The products prepared by this method have high purity but complex process flows, making it impossible to achieve industrial production. In addition, there is also a combination of chemical and physical methods. For example, 202310472113.0 discloses a method for preparing low-radiation spherical silicon micropowder for high-end fillers. In this method, ordinary silicon micropowder is taken out and put into a dust-free pulverizer for dust-free ultra-fine pulverization. After pulverization, it is put into a classification sieve for selection to obtain ultra-fine silicon micropowder. Then deionized water is added and put into a magnetic stirrer for mixing and stirring. After stirring, an acidic reagent is added to adjust the pH value of the mixed solution to an appropriate range to obtain a slurry; silica-based aerogel is evenly adhered to the pore walls of honeycomb ceramics. After even coating, it is put into an oven for high-temperature baking. After the adhesive is dried, dust-free nitrogen is introduced into the pores of the honeycomb ceramics to blow off the silica-based aerogel that is not completely adhered, obtaining a mesoporous adsorption device; a circulating water pump is used to pass the slurry through the mesoporous adsorption device to adsorb and separate the uranium element in the slurry. After repeating the adsorption and purification process 2-3 times, low-radiation spherical silicon micropowder is prepared. There are still some problems to be optimized for this product: (1) The mesoporous adsorption device uses aerogel evenly adhered to the pore walls of honeycomb ceramics, and a circulating water pump is used to pass the slurry through the mesoporous adsorption device to adsorb and separate the uranium element in the slurry, and the adsorption effect needs to be improved. (2) This method requires the pH value to be below 4.5 to obtain the slurry, which requires high production equipment. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the present invention provides a method and device for removing uranium and purifying silica powder. This method, in cooperation with the device, realizes the integrated operation of uranium adsorption and drying of silica powder, with a simple process and being suitable for industrial production.

[0005] To achieve the above object, on the one hand, the present invention provides a method for removing uranium and purifying silica powder, comprising the following steps:

[0006] (1) Preparation of slurry process: Water and uranium-containing silica powder are transported into a stirring tank, and the pH of the slurry is adjusted to 6 - 7 by an acidic reagent. Under the action of a stirrer, the silica powder is prepared into a slurry with good dispersibility; here, the acidic reagent is preferably 1.00 mol / L hydrochloric acid, which is used in combination with sodium hydroxide to adjust the pH of the solution. When the pH value is closer to 7, it is more beneficial to the adsorption of uranium.

[0007] (2) Uranium removal process: After the silica powder slurry is discharged from the stirring tank, it is transported through a first pipeline to a jet adsorption container, where it undergoes preliminary uranium adsorption through a first adsorption orifice plate. After uranium removal, it enters a spraying adsorption container through a second pipeline, and undergoes secondary uranium adsorption and removal through a second adsorption orifice plate in the spraying adsorption container. The silica powder slurry adsorbed and removed of uranium is discharged through a third pipeline.

[0008] (3) Slurry drying process: The above-mentioned discharged silica powder slurry is sent to a jet atomizer in a drying container for jet atomization. The atomized droplets come into contact with hot gas, drying the silica powder slurry droplets into silica powder, and then discharging it under the action of gravity.

[0009] Both the first adsorption orifice plate and the second adsorption orifice plate are graphene oxide sol honeycomb ceramic plates.

[0010] A further improvement of the present invention, the method for removing uranium and purifying silica powder, comprises the following steps:

[0011] (1) Preparation of slurry process: The uranium-containing silica powder is sent to a storage bin for storage through a screw conveyor, and then enters the stirring tank through a metering device; then the pH of the slurry is further adjusted to 6 - 7 by an acidic reagent. Water is transported by a water pump, enters the stirring tank through a water delivery pipeline, a flow meter and a control valve. Under the action of a stirrer, the silica powder is prepared into a slurry, and the water content of the slurry is 40% - 50%; the water content of the slurry has an impact on the uranium removal effect. Because the slurry needs to flow, if the water content is low, the fluidity of the slurry is small and the fluidity is poor, which will cause it unable to pass through the graphene oxide sol honeycomb ceramic plate; if the water content is high, the fluidity of the slurry is strong, which will lead to a reduction in the uranium removal efficiency through the graphene oxide sol honeycomb ceramic plate. In addition, in the present invention, the dryer for drying the slurry is preferably a spray dryer, which is more suitable for slurries with a water content of 40% - 50%.

[0012] (2) Uranium removal process: After the silica powder slurry is discharged from the stirring tank, it is transported by the first slurry pump through the first pipeline to the jet adsorption container, where it undergoes preliminary uranium adsorption through three layers of the first adsorption orifice plates. After uranium removal, it enters the spraying adsorption container through the second pipeline, and undergoes secondary uranium adsorption through three layers of the second adsorption orifice plates in the spraying adsorption container. The silica powder slurry with uranium adsorbed and removed is discharged through the third pipeline.

[0013] (3) Mud drying process: The second slurry pump transports the uranium-removed silica powder slurry discharged from the spraying adsorption container through the pipeline to the jet atomizer in the drying container for jet atomization. After being atomized into droplets with a size of 50 - 300 μm, it comes into contact with the hot gas from the hot blast stove, and heat exchange occurs. The temperature of the hot gas is preferably controlled between 200 - 350 °C, so that the mud droplets are dried into silica powder with a moisture content of less than 1% - 2%. By increasing the contact area between the hot gas and the mud, the drying rate is increased; then it accumulates in the discharge bin under the action of gravity and is discharged through the material conveying pipeline; after heat exchange, the waste gas containing fine dust enters the first cyclone dust collector and the second cyclone dust collector at an angle of 270° tangentially in sequence. After dust collection, it is discharged into the atmosphere through the exhaust gas pipeline. The powder collected by the two dust collections is discharged through the material conveying pipelines of the first dust collection pipe and the second dust collection pipe respectively.

[0014] For a further improvement of the present invention, the preparation method of the graphene oxide sol honeycomb ceramic plate is as follows:

[0015] (1) Preparation of graphene oxide: A mixture of graphene oxide hydrosol and solid sodium nitrate is added to concentrated sulfuric acid in a water bath environment. After stirring, potassium permanganate is added, and stirring is continued to make it react fully; then the mixture is continuously stirred in a water bath environment, deionized water is added, and stirring is continued; then hydrogen peroxide solution and deionized water are slowly added to the mixture to present a brown color. After standing, the bottom precipitate is graphite oxide; after washing, ultrasonic treatment, and freeze-drying, graphene oxide is obtained.

[0016] (2) Preparation of graphene oxide hydrosol: Graphene oxide is dispersed in deionized water, and ascorbic acid solution is added in a water bath environment, and ultrasonic treatment is carried out to obtain graphene oxide hydrosol.

[0017] (3) Preparation of graphene oxide sol honeycomb ceramic plate: Graphene oxide hydrosol is evenly adhered to the honeycomb ceramic plate and dried to obtain the graphene oxide sol honeycomb ceramic plate.

[0018] Preferably, the preparation method of the graphene oxide sol honeycomb ceramic plate is as follows:

[0019] (1) Preparation of graphene oxide: A mixture of 36 g of flaky graphene and 18 g of sodium nitrate solid was slowly added to 420 ml of concentrated sulfuric acid in a 0 °C water bath environment. After stirring for 1 hour, 60 g of potassium permanganate was slowly added and stirring continued for 1 hour to allow for full reaction. Then, the mixture was continuously stirred in a 40 °C water bath environment for 6 h, and 1000 ml of deionized water was added dropwise. The water bath environment was raised to 90 °C and stirring continued for 1 hour. Then, 60 ml of a 40% hydrogen peroxide solution and 800 ml of deionized water were slowly added to the mixture, which turned brown. After standing for 24 hours, the bottom precipitate was graphite oxide. It was repeatedly washed with 200% hydrochloric acid and deionized water, ultrasonically treated for 4 hours in a 0 °C water bath environment, and then placed in a freeze-drying oven. After freeze-drying for 36 h, graphene oxide was obtained.

[0020] (2) Preparation of graphene oxide hydrosol: 450 mg of graphene oxide was dispersed in 300 mL of deionized water, and a 35 mg / mL ascorbic acid solution was added in a water bath environment at 80 °C. After ultrasonic treatment for 10 minutes, graphene oxide hydrosol was obtained.

[0021] (3) Preparation of graphene oxide sol honeycomb ceramic plate: The graphene oxide hydrosol was evenly adhered to the honeycomb ceramic plate and dried in an oven at 50 °C for 6 hours to obtain the graphene oxide sol honeycomb ceramic plate.

[0022] Preferably, the pore diameter of the honeycomb ceramic plate is 75 ± 5 μm to ensure the flow-through of uranium-containing slurry.

[0023] On the other hand, the present invention provides a device for the uranium removal and purification method of silica powder, including a stirring tank, a first pipeline, a jet adsorption container, a second pipeline, a spraying adsorption container, a third pipeline, and a jet atomizer, which are connected end to end in sequence.

[0024] The jet atomizer is located inside the drying container, and the opening of the jet atomizer faces the hot air inlet direction of the drying container; the bottom of the drying container is connected to the material conveying pipeline.

[0025] The jet adsorption container and the spraying adsorption container are respectively internally provided with horizontally arranged adsorption orifice plates.

[0026] In a further improvement of the present invention, a storage bin is provided at the upper end of the stirrer. The storage bin is connected to the stirring tank through a feeding pipe, and a metering device is provided on the feeding pipe; a water conveying pipeline is also provided at the upper end of the stirring tank. One end of the water conveying pipeline is connected to a water pump, and the other end is located inside the stirring tank. A flow meter and a control valve are arranged on the water conveying pipeline.

[0027] In a further improvement of the present invention, a first slurry pump is provided on the first pipeline, and a second slurry pump is provided on the third pipeline.

[0028] The second pipeline is semi-circular to avoid material accumulation;

[0029] The nozzle of the jet atomizer is a rotating nozzle.

[0030] In a further improvement of the present invention, a hot air delivery pipeline is connected to the upper part of the drying container, and the other end of the hot air delivery pipeline is connected to a hot blast stove.

[0031] In a further improvement of the present invention, the drying container is connected to the upper part of the first cyclone dust collector; the top of the first cyclone dust collector is connected to the second cyclone dust collector, and the top of the second cyclone dust collector is connected to an exhaust gas pipeline; the first dust collection pipe at the bottom of the first cyclone dust collector is connected to a material delivery pipeline, and the second dust collection pipe at the bottom of the second cyclone dust collector is connected to the material delivery pipeline;

[0032] The air inlets of the first cyclone dust collector and the second cyclone dust collector are in the form of 270° volutes.

[0033] The structural forms of the jet adsorption container and the spraying adsorption container are: composed of an upper cone, a middle cylinder, and a lower cone. Three layers of first adsorption perforated plates are respectively arranged inside the jet adsorption container. The slurry is pumped by the first slurry pump, passes through the first pipeline, and is sprayed upward through the conical part of the jet adsorption container, so it is called the "jet adsorption container"; three layers of second adsorption perforated plates are also respectively arranged inside the spraying adsorption container. The slurry discharged from the jet adsorption container is sprayed into the adsorption container from top to bottom through the second pipeline, so it is called the "spraying adsorption container".

[0034] The movement trajectory of the slurry in the jet adsorption container belongs to the "spouting" type and the "backmixing" type of flow. The slurry sprays upward through the conical part of the jet adsorption container from the first pipeline at a very high flow rate (the speed can be controlled within the range of 15 - 25 m / s), forming a central upward flow, and at the same time passing through three layers of first adsorption perforated plates. When it flows to a certain height, the gravitational force of the slurry will cause it to generate a downward backmixing movement; when the slurry impacts the upper conical wall surface of the jet adsorption container, the reduction of the cross-sectional area causes further backmixing, and in countless backmixings, it overlaps and turbulently moves with the central upward flow, strengthening the residence time of the slurry in the jet adsorption container and contacting the first adsorption perforated plates countless times to improve the uranium removal effect.

[0035] The movement trajectory of the slurry inside the spraying adsorption container belongs to the "spraying" type and the "collection" type of flow. The slurry discharged from the second pipeline relies on gravity, and as the cross-sectional area of its upper cone gradually increases, the slurry disperses and the flow velocity gradually decreases, and the slurry is slowly sprayed onto the three layers of second adsorption perforated plates. When the slurry moves to the lower cone, the slurry is collected as the cross-sectional area of the lower cone gradually decreases, and at the same time, the second slurry pump also accelerates the collection work of the slurry to complete uranium removal.

[0036] The beneficial effects of the present invention are as follows:

[0037] (1) The first adsorption orifice plate and the second adsorption orifice plate adopted in the present invention are graphene oxide sol honeycomb ceramic plates. The oxygen-containing functional groups in graphene oxide endow it with strong adsorption ability for uranium. Especially under suitable pH conditions, the functional groups on the surface of graphene oxide undergo deprotonation reactions, forming negatively charged -O- or -COO- groups, which can form a strong chemical adsorption layer. The removal rate of uranium in the slurry is as high as 94.6%.

[0038] (2) The present invention realizes the dispersion of silicon micro-powder slurry through the injection adsorption container and the spraying adsorption container, improves the contact area between the material and the graphene oxide sol honeycomb ceramic plate, and greatly improves the adsorption effect. The process of the present invention is simple and suitable for the large-scale preparation of low-radioactivity spherical silicon micro-powder used in integrated circuits.

[0039] (3) The uranium removal and purification method of the present invention is simple. After configuring silicon micro-powder and water, an automatic uranium adsorption process is carried out, without too many complex operations, the operation is simpler, and the requirements for the equipment used are low.

[0040] (4) The preparation device of the present invention is reasonably designed, realizing the integrated operation of mixing, uranium removal, and drying of silicon micro-powder. And with the dust collector, it realizes the maximum utilization rate of raw materials and ecological environmental protection, and is suitable for industrial production. Brief Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic diagram of the overall mechanism of this device;

[0043] Figure 2 It is the SEM diagram of graphene oxide used in Examples 2, 3, and 4;

[0044] Figure 3 It is the SEM diagram and macroscopic photo of the graphene oxide hydrosol used in Examples 2, 3, and 4;

[0045] In the figure: 1 - screw conveyor; 2 - storage bin; 3 - metering device; 4 - water delivery pipe; 5 - flowmeter; 6 - water pump; 7 - control valve; 8 - mixing tank; 9 - stirrer; 10 - first slurry pump; 11 - first pipe; 12 - jet adsorption container; 13 - spraying adsorption container; 14 - first adsorption orifice plate; 15 - second pipe; 16 - second adsorption orifice plate; 17 - second slurry pump; 18 - third pipe; 19 - drying container, 20 - jet atomizer; 21 - hot blast stove; 22 - hot air delivery pipe; 23 - discharge bin; 24 - material delivery pipe; 25 - first cyclone dust collector; 26 - second cyclone dust collector; 27 - exhaust gas pipe; 28 - first dust collection pipe; 29 - second dust collection pipe. Detailed implementation manner

[0046] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0047] All raw materials used in the present invention are raw materials that can be purchased in the market. Graphene is sourced from Qingdao Jinrilai Graphite Co., Ltd. with a particle size of 325 mesh. Sodium nitrate, concentrated sulfuric acid, potassium permanganate, hydrogen peroxide, and ascorbic acid are all purchased from Sinopharm Group. The concentration of concentrated sulfuric acid is 98%. The honeycomb ceramic plate is sourced from Kunshan Teng'erhui Material Filter Factory.

[0048] I. Preparation of graphene oxide sol honeycomb ceramic plate

[0049] Example 1

[0050] (1) Preparation of graphene oxide: A mixture of 36 g of flaky graphene and 18 g of sodium nitrate solid was slowly added to 420 ml of concentrated sulfuric acid in a 0 °C water bath environment. After stirring for 1 hour, 60 g of potassium permanganate was slowly added and stirring was continued for 1 hour to allow full reaction; then the mixture was continuously stirred in a 40 °C water bath environment for 6 h, 1000 ml of deionized water was added dropwise, and the water bath environment was raised to 90 °C and stirring was continued for 1 hour; then 60 ml of hydrogen peroxide solution with a mass fraction of 40% and 800 ml of deionized water were slowly added to the mixture to present a brown color. After standing for 24 hours, the bottom precipitate was graphite oxide; it was repeatedly washed with hydrochloric acid with a mass fraction of 200% and deionized water. After washing, it was ultrasonically treated in a 0 °C water bath environment for 4 hours, and then placed in a freeze-drying oven. After freeze-drying for 36 h, graphene oxide was obtained;

[0051] (2) Preparation of graphene oxide aqueous sol: 450 mg of graphene oxide was dispersed in 300 mL of deionized water. A solution of ascorbic acid with a mass concentration of 35 mg / mL was added under a water bath environment at a temperature of 80 °C, and ultrasonic treatment was carried out for 10 minutes to obtain graphene oxide aqueous sol;

[0052] (3) Preparation of graphene oxide sol honeycomb ceramic plate: The graphene oxide aqueous sol was evenly adhered to the honeycomb ceramic plate, and dried in an oven at 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C for 4, 5, 6, 7, and 8 hours respectively to obtain the graphene oxide sol honeycomb ceramic plate.

[0053] Through comparison, it was found that too low a temperature and too short a reaction time would result in a low bonding degree of the graphene oxide sol honeycomb ceramic plate, while too high a temperature and too long a reaction time would cause cracking at the joints of the graphene oxide sol honeycomb ceramic plate. Therefore, a drying temperature of 50 °C and a drying time of 6 hours were selected for subsequent experiments. And this graphene oxide sol honeycomb ceramic plate was used for the first adsorption orifice plate 14 and the second adsorption orifice plate 16 in Examples 2, 3, and 4.

[0054] II. Method for purifying uranium from silica powder

[0055] Example 2

[0056] The method for purifying uranium from silica powder includes the following steps:

[0057] (1) Process of preparing slurry: The uranium-containing silica powder was sent to the storage bin 2 by the screw conveyor 1 for storage, and then entered the mixing tank 8 through the metering device 3; water was transported by the water pump 6, passed through the water pipeline 4, the flowmeter 5 and the control valve 7, and entered the mixing tank 8. Then, the pH of the slurry was adjusted to 7 with an acidic reagent, and the silica powder was prepared into slurry under the action of the stirrer 9. Among them, water and uranium-containing silica powder were transported to the mixing tank 8 in a ratio of 40:60, and finally a slurry with a moisture content of 40% was formed;

[0058] (2) Uranium removal process: After the silica powder slurry was discharged from the mixing tank 8, it was transported to the jet adsorption container 12 by the first slurry pump 10 through the first pipeline 11, and was preliminarily adsorbed for uranium through three layers of the first adsorption orifice plate 14. After uranium removal, it entered the spraying adsorption container 13 through the second pipeline 15, and was subjected to secondary adsorption and uranium removal through three layers of the second adsorption orifice plate 16 in the spraying adsorption container 13. The silica powder slurry adsorbed and removed uranium was discharged through the third pipeline 18;

[0059] (3) Mud drying process: The second mud pump 17 sends the uranium-removed silicon micro-powder mud discharged from the spraying and adsorption container 13 to the jet atomizer 20 in the drying container 19 through the pipeline 18 for jet atomization. After being atomized into droplets with a size of 50 - 300 μm, it contacts with the hot gas from the hot blast stove 21, and heat exchange occurs, drying the mud droplets into silicon micro-powder with a moisture content of less than 1%. Then, it accumulates in the discharge bin 23 under the action of gravity and is discharged through the material conveying pipeline 24. Uranium removal rate = (uranium content in the mud - uranium content in the uranium-removed mud) * 100% / uranium content in the mud. After detection, the uranium removal rate in the mud is 94.6%.

[0060] Example 3

[0061] (1) Mud preparation process: The uranium-containing silicon micro-powder is sent to the storage bin 2 by the screw conveyor 1 for storage, and then enters the stirring tank 8 through the metering device 3; water is transported by the water pump 6 and enters the stirring tank 8 through the water conveying pipeline 4, flowmeter 5 and control valve 7. Then, the pH of the slurry is further adjusted to 6.5 with an acidic reagent, and the silicon micro-powder is prepared into mud under the action of the stirrer 9. Among them, water and uranium-containing silicon micro-powder are transported to the stirring tank 8 in a ratio of 45:55, and finally, mud with a moisture content of 45% is formed.

[0062] (2) Uranium removal process: After the silicon micro-powder mud is discharged from the stirring tank 8, it is transported to the jet adsorption container 12 by the first mud pump 10 through the first pipeline 11, and undergoes preliminary uranium adsorption through three layers of the first adsorption orifice plates 14. After uranium removal, it enters the spraying and adsorption container 13 through the second pipeline 15, and undergoes secondary uranium adsorption removal through three layers of the second adsorption orifice plates 16 in the spraying and adsorption container 13. The silicon micro-powder mud adsorbed and removed of uranium is discharged through the third pipeline 18.

[0063] (3) Mud drying process: The second mud pump 17 sends the uranium-removed silicon micro-powder mud discharged from the spraying and adsorption container 13 to the jet atomizer 20 in the drying container 19 through the pipeline 18 for jet atomization. After being atomized into droplets with a size of 50 - 300 μm, it contacts with the hot gas from the hot blast stove 21, and heat exchange occurs, drying the mud droplets into silicon micro-powder with a moisture content of less than 1.5%. Then, it accumulates in the discharge bin 23 under the action of gravity and is discharged through the material conveying pipeline 24; after detection, the uranium removal rate in the mud is 90.8%.

[0064] Example 4

[0065] (1) Process of preparing slurry: The uranium-containing silicon micro-powder is sent to the storage bin 2 by the screw conveyor 1 for storage, and then enters the stirring tank 8 through the metering device 3; water is transported by the water pump 6 and enters the stirring tank 8 through the water delivery pipe 4, the flowmeter 5 and the control valve 7. Then, the pH of the slurry is adjusted to 6 by the acidic reagent, and the silicon micro-powder is prepared into slurry under the action of the stirrer 9. Among them, water and uranium-containing silicon micro-powder are transported to the stirring tank 8 in a ratio of 50:50, and finally slurry with a water content of 50% is formed.

[0066] (2) Uranium removal process: After the silicon micro-powder slurry is discharged from the stirring tank 8, it is transported to the jet adsorption container 12 by the first slurry pump 10 through the first pipeline 11, and undergoes preliminary uranium adsorption through three layers of the first adsorption orifice plates 14. After uranium removal, it enters the spraying adsorption container 13 through the second pipeline 15, and undergoes secondary uranium adsorption and removal through three layers of the second adsorption orifice plates 16 in the spraying adsorption container 13. The silicon micro-powder slurry adsorbed and removed of uranium is discharged through the third pipeline 18.

[0067] (3) Slurry drying process: The second slurry pump 17 sends the uranium-removed silicon micro-powder slurry discharged from the spraying adsorption container 13 to the jet atomizer 20 in the drying container 19 through the pipeline 18 for jet atomization. After being atomized into droplets with a size of 50 - 300 μm, it contacts with the hot gas from the hot blast stove 21, undergoes heat exchange, and the slurry droplets are dried into silicon micro-powder with a water content of less than 1.5%. Then, it accumulates in the discharge bin 23 under the action of gravity and is discharged through the material conveying pipeline 24. After detection, the uranium removal rate in the slurry is 87.2%.

[0068] Example 5

[0069] The difference from Example 2 is that the first adsorption orifice plate 14 and the second adsorption orifice plate 16 adopt simple honeycomb ceramic plates. After detection, the uranium content in the slurry has hardly changed.

[0070] III. Device for purifying silicon micro-powder by uranium removal

[0071] Example 6

[0072] For the device used in the method for purifying silicon micro-powder by uranium removal, it includes a stirring tank, a first pipeline, a jet adsorption container, a second pipeline, a spraying adsorption container, a third pipeline, and a jet atomizer that are connected end to end in sequence;

[0073] The jet atomizer is located inside the drying container, and the opening of the jet atomizer faces the hot air inlet direction of the drying container; the bottom of the drying container is connected to the material conveying pipeline;

[0074] The jet adsorption container and the spraying adsorption container are respectively internally provided with adsorption orifice plates arranged horizontally.

[0075] A storage bin is provided at the upper end of the stirrer. The storage bin is communicated with the mixing tank through a feeding pipe, and a metering device is provided on the feeding pipe. A water delivery pipeline is also provided at the upper end of the mixing tank. One end of the water delivery pipeline is communicated with a water pump, and the other end is located inside the mixing tank. A flowmeter and a control valve are arranged on the water delivery pipeline.

[0076] A first slurry pump is provided on the first pipeline, and a second slurry pump is provided on the third pipeline.

[0077] The second pipeline is semi-circular.

[0078] The nozzle of the jet atomizer is a rotary nozzle.

[0079] A hot air delivery pipeline is communicated with the upper part of the drying container, and the other end of the hot air delivery pipeline is communicated with a hot blast stove.

[0080] The drying container is communicated with the upper part of the first cyclone dust collector. The top of the first cyclone dust collector is communicated with the second cyclone dust collector, and the top of the second cyclone dust collector is communicated with an exhaust gas pipeline. The first dust collection pipe at the bottom of the first cyclone dust collector is communicated with a material conveying pipeline, and the second dust collection pipe at the bottom of the second cyclone dust collector is communicated with the material conveying pipeline.

[0081] The air inlets of the first cyclone dust collector 25 and the second cyclone dust collector 26 are in the form of 270° volutes. After heat exchange, the exhaust gas containing fine dust enters the first cyclone dust collector 25 and the second cyclone dust collector 26 at an angle of 270° tangentially in sequence. After dust collection, it is discharged into the atmosphere through the exhaust gas pipeline 27. The powder collected twice is discharged through the material conveying pipeline 24 of the first dust collection pipe 28 and the second dust collection pipe 29 respectively.

[0082] Example 7

[0083] The difference from Example 6 is that the air inlets of the first cyclone dust collector 25 and the second cyclone dust collector 26 are in the form of 90° volutes.

[0084] Example 8

[0085] The difference from Example 6 is that the air inlets of the first cyclone dust collector 25 and the second cyclone dust collector 26 are in the form of 180° volutes.

[0086] After comparison, the 270° volute form has the best gas-solid separation effect, and the separation efficiency reaches more than 98%. Therefore, the 270° volute form is adopted.

[0087] Although the present invention has been described in detail by referring to the accompanying drawings and in conjunction with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and all such modifications or substitutions should fall within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily conceive of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for purifying silicon powder by removing uranium, characterized in that: The following steps are involved: (1) Slurry preparation process: water and uranium-containing silicon micropowder are transported to a stirring tank (8), the pH of the slurry is adjusted to 6-7 by an acidic reagent, and the silicon micropowder is prepared into a slurry with good dispersibility under the action of a stirrer (9); (2) Uranium removal process: After being discharged from the stirring tank (8), the silicon micropowder slurry is transported to the spray adsorption container (12) through the first pipeline (11), and undergoes preliminary uranium adsorption through the first adsorption orifice plate (14). After uranium is removed, the silicon micropowder slurry enters the spray adsorption container (13) through the second pipeline (15), undergoes secondary adsorption and uranium removal through the second adsorption orifice plate (16) in the spray adsorption container (13), and the silicon micropowder slurry from which uranium is removed is discharged through the third pipeline (18); (3) Slurry drying process: The discharged silicon micropowder slurry is sent to the spray atomizer (20) in the drying container (19) for spray atomization, and the atomized droplets come into contact with the hot gas, so that the silicon micropowder slurry droplets are dried to silicon micropowder, and then discharged under the action of gravity; The first adsorption hole plate and the second adsorption hole plate are both graphene oxide sol honeycomb ceramic plates.

2. The method for removing uranium from silicon powder according to claim 1, characterized in that: The following steps are involved: (1) Mud preparation process: uranium-containing silicon micropowder is sent to the storage bin (2) for storage via a screw conveyor (1), and then enters the stirring tank (8) via a metering device (3); water is transported via a water pump (6), and enters the stirring tank (8) via a water pipeline (4), a flow meter (5) and a control valve (7); the mud is further adjusted to a pH of 6-7 by an acidic reagent, and the silicon micropowder is prepared into mud under the action of a stirrer (9), and the water content of the mud is 40%-50%; (2) Uranium removal process: After being discharged from the stirring tank (8), the silicon micropowder slurry is transported to the spray adsorption container (12) by the first mud pump (10) through the first pipeline (11), passes through the three-layer first adsorption orifice plate (14) for preliminary uranium adsorption, and after uranium is removed, enters the spray adsorption container (13) through the second pipeline (15), and undergoes secondary adsorption and uranium removal in the spray adsorption container (13) through the three-layer second adsorption orifice plate (16). The silicon micropowder slurry from which uranium is removed is discharged through the third pipeline (18); (3) Mud drying process: The second mud pump (17) sends the uranium-free silicon micropowder mud discharged from the spray adsorption container (13) to the spray atomizer (20) in the drying container (19) through the pipeline (18) for spray atomization. After being atomized into droplets of 50-300 μm, the droplets come into contact with the hot gas from the hot air furnace (21) to exchange heat, so that the mud droplets are dried to silicon micropowder with a moisture content of less than 1%-2%. The droplets are then accumulated in the discharge bin (23) under the action of gravity and discharged through the material conveying pipeline (24); After heat exchange, the exhaust gas containing fine dust enters the first cyclone dust collector (25) and the second cyclone dust collector (26) at a tangential angle of 270 degrees in turn, and is discharged into the atmosphere through the exhaust gas pipe (27) after dust collection. The powder collected twice is discharged from the material conveying pipe (24) of the first dust collecting pipe (28) and the second dust collecting pipe (29) respectively.

3. The method for removing uranium from silicon micropowder according to any one of claims 1 to 2, characterized in that: The preparation method of the graphene oxide sol honeycomb ceramic plate is as follows: (1) Preparation of graphene oxide: A solid mixture of graphene and sodium nitrate is added to concentrated sulfuric acid in a water bath, and potassium permanganate is added after stirring, and stirring is continued to allow the mixture to react fully; then the mixture is stirred in a water bath, and deionized water is added and stirred; hydrogen peroxide solution and deionized water are slowly added to the mixture to present a brown color, and after standing, the bottom precipitate is graphite oxide; after washing, ultrasonication, and freeze-drying, graphene oxide is obtained; (2) Preparation of graphene oxide hydrosol: Graphene oxide is dispersed in deionized water, ascorbic acid solution is added in a water bath, and graphene oxide hydrosol is obtained by ultrasonic treatment; (3) Preparation of graphene oxide sol honeycomb ceramic plate: Graphene oxide aqueous sol is uniformly adhered to the honeycomb ceramic plate and dried to obtain the graphene oxide sol honeycomb ceramic plate.

4. The method for removing uranium from silicon micropowder according to claim 3, characterized in that: The preparation method of the graphene oxide sol honeycomb ceramic plate is as follows: In the step (1), the mass ratio of graphene to sodium nitrate and potassium permanganate is 18:9:30; in the step (2), the concentration of the ascorbic acid solution is 35 mg / mL; in the step (3), the drying temperature is 50°C±5°C, and the drying time is 6±1 hours.

5. The method for purifying silicon powder by removing uranium according to claim 3, characterized in that: The preparation method of the graphene oxide sol honeycomb ceramic plate is as follows: (1) Preparation of graphene oxide: 36 g of flaky graphene and 18 g of sodium nitrate solid mixture were slowly added to 420 ml of concentrated sulfuric acid in a 0°C water bath environment. After stirring for 1 hour, 60 g of potassium permanganate was slowly added and stirred for 1 hour to allow it to fully react. The mixture was then stirred for 6 hours in a 40°C water bath environment, and 1000 ml of deionized water was added dropwise, and the water bath environment was raised to 90°C, and stirring was continued for 1 hour. 60 ml of 40% hydrogen peroxide solution and 800 ml of deionized water were slowly added to the mixture and turned brown. After standing for 24 hours, the bottom precipitate was graphite oxide. The mixture was repeatedly washed with 200% hydrochloric acid and deionized water, and after washing, it was ultrasonicated in a 0°C water bath environment for 4 hours, and then placed in a freeze drying oven and freeze-dried for 36 hours to obtain graphene oxide. (2) Preparation of graphene oxide hydrosol: 450 mg of graphene oxide was dispersed in 300 mL of deionized water, and an ascorbic acid solution with a mass concentration of 35 mg / mL was added in a water bath at a temperature of 80° C. The solution was ultrasonicated for 10 minutes to obtain a graphene oxide hydrosol; (3) Preparation of graphene oxide sol honeycomb ceramic plate: Graphene oxide aqueous sol is uniformly adhered to the honeycomb ceramic plate, and dried in an oven at 50° C. for 6 hours to obtain a graphene oxide sol honeycomb ceramic plate.

6. The method for purifying silicon powder by removing uranium according to claim 3, characterized in that: The pore diameter on the honeycomb ceramic plate is 75±5μm.

7. A device for the method for purifying silicon micropowder by removing uranium according to any one of claims 1 to 2, characterized in that: It includes a stirring tank, a first pipeline, a spray adsorption container, a second pipeline, a spray adsorption container, a third pipeline, and a spray atomizer which are connected end to end in sequence; The jet atomizer is located inside the drying container, and the opening of the jet atomizer faces the hot air inlet of the drying container; the bottom of the drying container is connected to the material conveying pipeline; The jet adsorption container and the spray adsorption container are respectively provided with horizontally arranged adsorption orifice plates therein.

8. The device according to claim 7, characterized in that: A storage bin is provided at the upper end of the agitator, which is connected to the mixing tank through a feed discharge pipe, and a metering device is provided on the feed discharge pipe; a water supply pipeline is also provided at the upper end of the mixing tank, one end of the water supply pipeline is connected to the water pump, and the other end is located in the mixing tank, and a flow meter and a control valve are arranged on the water supply pipeline.

9. The device according to claim 7, characterized in that: The first pipeline is provided with a first mud pump, and the third pipeline is provided with a second mud pump; The second pipe is semicircular; The nozzle of the jet atomizer is a rotating nozzle; The upper part of the drying container is connected with a hot air delivery pipeline, and the other end of the hot air delivery pipeline is connected with a hot air furnace.

10. The device according to claim 7, characterized in that: The drying container is connected to the upper part of the first cyclone dust collector; the top of the first cyclone dust collector is connected to the second cyclone dust collector, and the top of the second cyclone dust collector is connected to the exhaust gas pipeline; the first dust collecting pipe at the bottom of the first cyclone dust collector is connected to the material conveying pipeline, and the second dust collecting pipe at the bottom of the second cyclone dust collector is connected to the material conveying pipeline; The air inlets of the first cyclone dust collector and the second cyclone dust collector are in the form of a 270° volute.

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