阅读说明：本技术 赤泥放射性屏蔽剂及屏蔽赤泥放射性的方法 (Red mud radioactive shielding agent and method for shielding red mud radioactivity ) 是由 黄术军 果世驹 尹志超 于 2021-06-15 设计创作，主要内容包括：本发明提供一种赤泥放射性屏蔽剂及屏蔽赤泥放射性的方法。所述赤泥放射性屏蔽剂是一种烧结扩散型粉末,包括金属粉末与非金属粉末。所述金属粉末包括铅、钡、铋、钨、铁、铬、及镍中之一种或多种。所述非金属粉末包括硼酸、氧化硼、及氧化铋中之一种或多种。本发明采用粉末冶金工艺,通过混粉、压制、烧结扩散、破碎、细磨等工序制备出一定细度的赤泥放射性屏蔽剂。将一定量的赤泥放射性屏蔽剂添加到赤泥浆料中,球磨、干燥后获得干屏蔽赤泥,实现对电解铝固体废物赤泥的放射性屏蔽,从而达到国家标准放射性核素限量要求,以便于能够大规模利用该固体废弃物赤泥,建设绿色环保的生态环境,实现人与自然和谐共处。(The invention provides a red mud radioactive shielding agent and a method for shielding red mud radioactivity. The red mud radioactive shielding agent is sintered diffusion type powder and comprises metal powder and nonmetal powder. The metal powder includes one or more of lead, barium, bismuth, tungsten, iron, chromium, and nickel. The non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide. The red mud radioactive shielding agent with a certain fineness is prepared by adopting a powder metallurgy process through the working procedures of powder mixing, pressing, sintering diffusion, crushing, fine grinding and the like. A certain amount of red mud radioactive shielding agent is added into the red mud slurry, and the dry shielding red mud is obtained after ball milling and drying, so that the radioactive shielding of the electrolytic aluminum solid waste red mud is realized, the national standard radionuclide limit requirement is met, the solid waste red mud can be utilized on a large scale, a green and environment-friendly ecological environment is built, and the harmonious coexistence of human and nature is realized.)

1. The red mud radioactive shielding agent is characterized by comprising metal powder and non-metal powder, wherein the metal powder comprises one or more of lead, barium, bismuth, tungsten, iron, chromium and nickel powder, and the non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide powder.

2. The red mud radioactive shielding agent of claim 1, wherein the weight ratio of the non-metal powder to the metal powder is 1:4 to 1: 160.

3. The red mud radioactive shielding agent of claim 2, wherein the metal powder is iron powder and bismuth powder, and the non-metal powder is boric acid powder; the iron powder is 20-80 parts by weight, the bismuth powder is 20-80 parts by weight, and the boric acid powder is 1-10 parts by weight.

4. The method for shielding radioactivity of red mud is characterized by comprising the following steps:

step 1, providing a red mud radioactive shielding agent, and uniformly mixing the red mud radioactive shielding agent to obtain mixed powder;

the red mud radioactive shielding agent comprises metal powder and non-metal powder, wherein the metal powder comprises one or more of lead, barium, bismuth, tungsten, iron, chromium and nickel powder, and the non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide powder;

step 2, putting the mixed powder into a closed die, and pressing and forming to prepare a shielding agent green body;

step 3, sintering thermal diffusion is carried out on the shielding agent green body to form a sintered block;

step 4, crushing the sintered blocks to obtain shielding agent powder;

screening the shielding agent powder to obtain the red mud radioactive shielding agent;

step 6, providing wet red mud and preparing red mud slurry;

step 7, adding the red mud radioactive shielding agent obtained in the step 5 into the red mud slurry to obtain a red mud shielding agent mixed slurry;

step 8, ball-milling and aging the red mud screening agent mixed slurry, and sieving to obtain wet screening red mud slurry;

and 9, drying the wet shielding red mud slurry to obtain the dry shielding red mud.

5. The method for shielding radioactivity of red mud according to claim 4, wherein the metal powder is iron powder and bismuth powder, and the non-metal powder is boric acid powder; 20-80 parts of iron powder, 20-80 parts of bismuth powder and 1-10 parts of boric acid powder;

in the step 1, the red mud radioactive shielding agents are mixed at room temperature in a dry mixing manner.

6. The method for shielding radioactivity of red mud according to claim 4, wherein in the step 2, uniaxial and bidirectional pressing is carried out by a hydraulic press to prepare a green shielding agent; in the step 3, the sintering diffusion temperature range is 300-800 ℃.

7. The method for shielding radioactivity in red mud according to claim 4, wherein the step 4 specifically comprises: the sintered cake is first crushed into small pieces, and the small pieces are mechanically ground to obtain the shielding agent powder.

8. The method for shielding red mud radioactivity of claim 4, wherein the step 5 further comprises measuring the performance of the red mud radioactive shielding agent, performing X-ray diffraction analysis and scanning electron microscopy analysis, and measuring the apparent density of the red mud radioactive shielding agent, wherein the acceptable range of the apparent density is 1.5-2.1 g/cc.

9. The method for shielding red mud radioactivity of claim 4, wherein in the step 7, the amount of the red mud radioactivity shielding agent is 0.5-2.0 wt% of the red mud slurry.

10. The method for shielding radioactivity of red mud according to claim 4, wherein the dry shielding red mud obtained in the step 9 is in the form of loose blocks and powder particles, and the water content of the dry shielding red mud is 6-8%.

Technical Field

The invention relates to the field of red mud recycling, in particular to a red mud radioactive shielding agent and a method for shielding red mud radioactivity.

Background

Red mud is an industrial solid waste discharged after alumina is extracted from bauxite in the aluminum production industry. Generally, the iron oxide is contained in a large amount, and the appearance of the iron oxide is similar to that of red soil, so the iron oxide is named. 0.6-2 tons of red mud is discharged when 1 ton of alumina is produced, domestic manufacturers generally stack outdoor wasteland, and in order to avoid air pollution caused by floating of the alumina in the air, watering is needed, and certain humidity is kept, so that the alumina is stored in a wet red mud block mode. The red mud has chemical properties such as high alkalinity and certain radioactive physical properties. The nuclides in the red mud mainly comprise radium-226 and thorium-232. The detection shows that the radionuclide of the megaton-level stacked red mud exceeds the standard, the internal radiation index (IRa) is 1.7, the external radiation index (Ir) is 2.6, and the values exceed the limit values of the national standard requirements (the value specified by the C/D472-200 standard is that IRa is less than or equal to 1.0, and Ir is less than or equal to 1.0). The radioactivity of red mud is a real and long-term threat to the ecological environment.

Chinese patent (CN101219883A, red mud baking-free brick and manufacturing method) states that during the process of manufacturing the red mud baking-free brick, barium sulfate powder is added to inhibit the radioactivity of the red mud mixture. The technical scheme is as follows: the red mud baking-free brick comprises, by weight, 22-42% of red mud, 20-40% of fly ash, 20-30% of sandstone, 3-7% of gypsum, 6-10% of lime and 0.1-1% of barium sulfate powder, and is prepared by a natural curing or autoclaved process, and the radioactivity of the brick does not exceed the national standard.

The technical literature (patent and technical analysis on the preparation of baking-free bricks by using red mud, author: Chenjunjie, Yao Mei Yu, Guangdong chemical engineering, 2019, 46 (14): 110-.

Technical literature (preparation of modified red mud baking-free bricks and radioactive shielding mechanism analysis- "mineral protection and utilization", authors: Yangyan, Lijianwei, Zhangliang, martin, Yihui, horse stile, 2019, 39 (1): 95-99) records that red mud is treated by quicklime and barium sulfate, a mixture is prepared according to the ratio of m (red mud): m (quicklime): m (barium sulfate): 100:20:1, the mixture is uniformly stirred, then a slurry is prepared according to the ratio of m (water): m (mixture): 2:1, the slurry is heated to 90 ℃ by adopting a flat electric furnace, and the slurry fully reacts for 6 hours at 90 ℃ to obtain the modified red mud. The internal irradiation index is 1.518, the external irradiation index is 1.3, the limit value of national standard regulation of building main bodies is still exceeded, and the use is limited.

Technical literature (research on natural radioactivity level of red mud and restriction in the field of building materials- "light metals", author: consider Han Mian, Wanning, Zhang Ming, Wanjun, Tang hong Feng, Tian Yuan Jiang, 2011, (5): 19-21) indicates that the energy spectrum method and the element conversion method can meet the radioactivity level determination of solid samples such as red mud, and when measuring the red mud sample, the internal irradiation index and the external irradiation index of the red mud, whether the red mud is sintered red mud or Bayer red mud, exceed the radionuclide limitation requirement of the building material, and cannot be directly used for the building main body material.

In particular, the technical literature (research on radioactivity change rule of red mud hydration process-silicate report, author: Chongfei, Luozao, Wangxing, Lianghui, Yanjijun, 2015, 34 (9): 2579, 25252584) shows that: at present, the field of consuming a large amount of bayer process red mud waste residues is the building material industry, but the natural radioactivity level of bayer process red mud is generally higher, if bayer process red mud is used as a building material or a building material additive, a human body is exposed to radiation for a long time to generate a so-called radioactive hazard phenomenon (genetic mutation and chromosome variation caused by radioactivity, genetic substances of the human body are damaged, one generation or even several generations of people are damaged, high-dose radiation can cause death of the people, and long-term low-dose radiation can cause headache, dizziness and tinnitus, sleep disorder, memory impairment, skin injury and the like), and the radioactive hazard becomes one of main factors restricting large-scale comprehensive utilization of bayer process red mud in the field of building materials.

As described above, the problem of radioactive shielding of red mud, which is a naturally piled state, by a large amount of electrolytic aluminum solid waste is not effectively solved. Red mud is a real and even long-standing pollution source which can cause harm to the ecological environment and human health. Therefore, it is necessary and urgent to further develop the radioactive shielding technology of red mud, effectively reduce the nuclide release of red mud, and utilize the solid waste red mud in a large scale, so as to construct a green ecological environment and improve the quality of life of people.

Disclosure of Invention

The invention aims to provide a red mud radioactive shielding agent which can be added into red mud so as to shield the radioactivity of the red mud.

The invention also aims to provide a method for shielding the radioactivity of the red mud, which can utilize the solid waste red mud on a large scale, thereby saving the space for stacking the red mud, shielding the radioactivity of the red mud and being beneficial to building a green and environment-friendly ecological environment.

In order to achieve the above purpose, the present invention provides a red mud radioactive shielding agent, which comprises metal powder and non-metal powder, wherein the metal powder comprises one or more of lead, barium, bismuth, tungsten, iron, chromium, and nickel powder, and the non-metal powder comprises one or more of boric acid, boron oxide, and bismuth oxide powder.

The weight ratio of the non-metal powder to the metal powder is 1:4 to 1: 160.

The metal powder is iron powder and bismuth powder, and the non-metal powder is boric acid powder; the iron powder is 20-80 parts by weight, the bismuth powder is 20-80 parts by weight, and the boric acid powder is 1-10 parts by weight.

The invention also provides a method for shielding the radioactivity of the red mud, which comprises the following steps:

step 1, providing a red mud radioactive shielding agent, and uniformly mixing the red mud radioactive shielding agent to obtain mixed powder;

the red mud radioactive shielding agent comprises metal powder and non-metal powder, wherein the metal powder comprises one or more of lead, barium, bismuth, tungsten, iron, chromium and nickel powder, and the non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide powder;

step 2, putting the mixed powder into a closed die, and pressing and forming to prepare a shielding agent green body;

step 3, sintering thermal diffusion is carried out on the shielding agent green body to form a sintered block;

step 4, crushing the sintered blocks to obtain shielding agent powder;

screening the shielding agent powder to obtain the red mud radioactive shielding agent;

step 6, providing wet red mud and preparing red mud slurry;

step 7, adding the red mud radioactive shielding agent obtained in the step 5 into the red mud slurry to obtain a red mud shielding agent mixed slurry;

step 8, ball-milling and aging the red mud screening agent mixed slurry, and sieving to obtain wet screening red mud slurry;

and 9, drying the wet shielding red mud slurry to obtain the dry shielding red mud.

The metal powder is iron powder and bismuth powder, and the non-metal powder is boric acid powder; 20-80 parts of iron powder, 20-80 parts of bismuth powder and 1-10 parts of boric acid powder;

in the step 1, the red mud radioactive shielding agents are mixed at room temperature in a dry mixing manner.

In the step 2, uniaxial and bidirectional pressing is carried out by adopting a hydraulic press to prepare a shielding agent green body; in the step 3, the sintering diffusion temperature range is 300-800 ℃.

The step 4 specifically includes: the sintered cake is first crushed into small pieces, and the small pieces are mechanically ground to obtain the shielding agent powder.

And the step 5 also comprises the steps of measuring the performance of the red mud radioactive shielding agent, carrying out X-ray diffraction analysis and scanning electron microscopy analysis, and measuring the apparent density of the red mud radioactive shielding agent, wherein the qualified range of the apparent density is 1.5-2.1 g/cc.

In the step 7, the addition amount of the red mud radioactive shielding agent is 0.5-2.0 wt% of the red mud slurry.

The dry shielding red mud obtained in the step 9 is in a loose block and a granular state, and the water content of the dry shielding red mud is 6-8%.

The invention has the beneficial effects that: the invention provides a red mud radioactive shielding agent and a method for shielding red mud radioactivity. The red mud radioactive shielding agent is sintered diffusion type powder and comprises metal powder and nonmetal powder. The metal powder includes one or more of lead, barium, bismuth, tungsten, iron, chromium, and nickel. The non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide. The radioactive level of nuclides of the red mud can be obviously reduced by adding a red mud radioactive shielding agent into the red mud. The red mud radioactive shielding agent with a certain fineness is prepared by adopting a powder metallurgy process through the working procedures of powder mixing, pressing, sintering diffusion, crushing, fine grinding and the like. A certain amount of red mud radioactive shielding agent is added into the red mud slurry, and the dry shielding red mud is obtained after ball milling and drying, so that the radioactive shielding of the electrolytic aluminum solid waste red mud is realized, the national standard radionuclide limit requirement is met, the solid waste red mud can be utilized on a large scale, a green and environment-friendly ecological environment is built, and the harmonious coexistence of human and nature is realized.

Detailed Description

To further illustrate the technical means adopted by the present invention and the effects thereof, the following detailed description is given with reference to the preferred embodiments of the present invention.

The invention provides a red mud radioactive shielding agent, which comprises metal powder and non-metal powder, wherein the metal powder comprises one or more of lead (Pb), barium (Ba), bismuth (Bi), tungsten (W), iron (Fe), chromium (Cr) and nickel (Ni) powder, and the non-metal powder comprises boric acid (HBO)₃) Boron oxide (B)₂O₃) And bismuth oxide (Bi)₂O₃) One or more of the powders.

Specifically, the weight ratio of the non-metal powder to the metal powder is 1:4 to 1: 160.

Preferably, the metal powder is Fe and Bi powder, and the non-metal powder is boric acid powder. 20-80 parts of iron powder, 20-80 parts of bismuth powder and 1-10 parts of boric acid powder. The boric acid powder is more preferably 2 to 6 parts by weight.

The red mud radioactive shielding agent is used for being added into red mud so as to shield the radioactivity of the red mud, and realize the radioactive shielding of the red mud of the electrolytic aluminum solid waste, so that the national standard radionuclide limit requirement is met, and the solid waste red mud can be conveniently utilized in a large scale.

Based on the red mud radioactive shielding agent, the invention also provides a method for shielding the radioactivity of the red mud, which comprises the following steps:

step 1, providing a red mud radioactive shielding agent, and uniformly mixing the red mud radioactive shielding agent to obtain mixed powder.

Specifically, the red mud radioactive shielding agent comprises metal powder and non-metal powder, wherein the metal powder comprises one or more of lead (Pb), barium (Ba), bismuth (Bi), tungsten (W), iron (Fe), chromium (Cr) and nickel (Ni) powder, and the non-metal powder comprises boric acid (HBO)₃) Boron oxide (B)₂O₃) And bismuth oxide (Bi)₂O₃) One or more of the powders.

Preferably, the metal powder is Fe and Bi powder, and the non-metal powder is boric acid powder. 20-80 parts of iron powder, 20-80 parts of bismuth powder and 1-10 parts of boric acid powder. The boric acid powder is more preferably 2 to 6 parts by weight.

Specifically, the red mud radioactive shielding agent is mixed in a dry mixing mode at room temperature, and the step 1 specifically comprises the steps of putting the red mud radioactive shielding agent into a 3-dimensional mixer, adding 1-3 parts by weight of forming agent powder, enabling the rotating speed of a main machine of the mixer to be 30-50 r/min, enabling a charging bucket to move in a 3-dimensional mode, and mixing for 1-3 hours to obtain mixed powder.

Optionally, the forming agent powder is PEG80F wax powder.

And 2, filling the mixed powder into a closed die, and pressing and forming to prepare a shielding agent green body.

Specifically, in the step 2, uniaxial and bidirectional pressing is carried out by adopting a hydraulic press to prepare a shielding agent green body. The step 2 specifically comprises the steps of filling the mixed powder into a closed steel die, and carrying out uniaxial two-way pressing on a 200t oil press, wherein the pressing pressure is 4-8 t/cm²And keeping the pressure for 8-12 s, and obtaining a shielding agent green body after demolding.

And 3, sintering and thermally diffusing the shielding agent green body to form a sintered block.

Specifically, in the step 3, the green shielding agent is subjected to sintering thermal diffusion in a powder metallurgy push rod type sintering furnace. Specifically, the shielding agent green body is loaded into a sintering boat and placed on a hearth bottom plate of a sintering furnace, a mechanical push rod pushes the sintering boat to continuously move forwards, and the sintering boat sequentially passes through a preheating zone, a high-temperature zone, a low-temperature zone and a cooling zone to complete sintering heat diffusion. The boat pushing speed is 1-3 boats/10 min, the heat diffusion temperature is 300-800 ℃, and the heat diffusion time is 1-3 h. In order to prevent the shielding agent green compact from being excessively oxidized, a furnace chamber of the sintering furnace is filled with a flowing protective atmosphere, and the protective atmosphere is a mixed gas of hydrogen and nitrogen. After sintering diffusion, a porous shielding agent thermal diffusion sintering block is formed.

And 4, crushing the sintered block to obtain shielding agent powder.

Specifically, the step 4 specifically includes: the sintered cake is first crushed into small pieces, and the small pieces are mechanically ground to obtain the shielding agent powder. For mechanical grinding, the side length of each edge of the small block should be less than 3 mm.

And 5, screening the shielding agent powder to obtain the red mud radioactive shielding agent.

Specifically, in the step 5, a miller sieve is adopted for sieving to obtain shielding agent powders with different fine grades, preferably, all the shielding agent powders are sieved by a 100-mesh sieve, and the sieved substances are red mud radioactive shielding agents.

Specifically, the step 5 further comprises the steps of measuring the performance of the red mud radioactive shielding agent, performing X-ray diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) analysis, and measuring the apparent density of the red mud radioactive shielding agent, wherein the qualified range of the apparent density is 1.5-2.1 grams per cubic centimeter.

And step 6, providing wet red mud and preparing red mud slurry.

Specifically, the step 6 specifically includes: removing visible impurities on the wet red mud blocks in a red mud piling field, mashing the wet red mud blocks, pouring the wet red mud blocks into a nylon tank, adding tap water and a suspending agent, wherein the weight ratio of the red mud to the tap water to the PEG2000 is 1: 1.8-2.2: 0.008-0.012, and grinding media are one or more of tungsten carbide-cobalt hard alloy balls with the diameter of phi 10, phi 6 or phi 3 mm. And rolling the nylon tank on a roller lever type mixer at the rotating speed of 30-50 r/min for 3-5 h to obtain the red mud slurry.

Optionally, the suspending agent is PEG 2000.

Specifically, the addition amount of the red mud radioactive shielding agent is 0.5-2.0 wt% of the red mud slurry.

And 7, adding the red mud radioactive shielding agent obtained in the step 5 into the red mud slurry to obtain a red mud shielding agent mixed slurry.

And 8, performing ball milling and aging on the red mud screening agent mixed slurry, and sieving to obtain the wet screening red mud slurry.

Specifically, the step 8 specifically comprises the steps of ball milling the red mud screening agent mixed slurry for 7-9 hours, stopping the mill, keeping the mill in a nylon tank for 70-74 hours for precipitation and aging, discharging after aging, separating milled media, and sieving by a 25-mesh sieve, wherein undersize products are wet screening red mud slurry.

And 9, drying the wet shielding red mud slurry to obtain the dry shielding red mud.

Specifically, the step 9 specifically includes placing the wet shielding red mud slurry in a ventilated oven, and preserving heat for 10-24 hours at a temperature of 110-130 ℃ to obtain the dry shielding red mud.

The dry shielding red mud is in loose block and granular shape, and the water content of the dry shielding red mud is 6-8%.

The method for shielding the radioactivity of the red mud is simple and feasible, and combines the multi-component shielding agents, so that the shielding effect of a single component is fully exerted, the interaction among the components is exerted, and the shielding effect is improved. The problem of radioactive pollution of the red mud can be solved, so that the storage problem of the red mud is solved, transportation and downstream workers can work in a green environment, and a safe, healthy and efficient working environment is constructed. When the dry shielding red mud loose agglomerate is used as a building material, the radioactivity of the dry shielding red mud loose agglomerate and powder particles finally obtained meets the national standard limit requirements, so that the dry shielding red mud loose agglomerate and powder particles can have wider development and utilization space, and have positive promoting significance for high-level treatment and large-scale utilization of solid waste red mud.

The following is a specific embodiment of the present invention:

step 1, the red mud radioactive shielding agent adopts reduced iron powder with the granularity of 100 meshes, and the purity is more than 99 percent; bismuth powder with granularity of 100 meshes and purity of more than 99.9 percent; and boric acid powder with a particle size of 200 meshes, and is chemically pure. 50 parts of iron powder, 50 parts of bismuth powder and 5 parts of boric acid powder by weight, and preparing 10Kg of mixed powder according to the weight proportion. And putting the weighed powder into a 3-dimensional mixer for mixing, adding 2 parts by weight of PEG80F wax powder forming agent powder, rotating at the speed of 40 r/min by a host machine, performing 3-dimensional motion on a charging basket, and mixing for 2 hours to obtain mixed powder.

Step 2, filling the mixed powder into a closed steel die, and carrying out uniaxial and bidirectional pressing on a 200t oil press, wherein the pressing pressure is 6t/cm²And keeping the pressure for 10s, and obtaining a shielding agent green body after demolding.

And 3, sintering and thermally diffusing the shielding agent green body in a powder metallurgy push rod type sintering furnace. Specifically, the shielding agent green body is put into a sintering boat (with the size of 320cm x 210cm x 35cm), and is placed on a hearth bottom plate of a sintering furnace, a mechanical push rod pushes the sintering boat to continuously move forwards, and the sintering boat sequentially passes through a preheating zone, a high-temperature zone, a low-temperature zone and a cooling zone to finish sintering heat diffusion. The boat pushing speed is 2 boats/10 min, the heat diffusion temperature is 500 ℃, and the heat diffusion time is 2 h. In order to prevent the shielding agent green compact from being excessively oxidized, a furnace chamber of the sintering furnace is filled with a flowing protective atmosphere, and the protective atmosphere is 10% of hydrogen and 90% of nitrogen. After sintering diffusion, a porous shielding agent thermal diffusion sintering block is formed.

And 4, crushing the thermal diffusion sintered block into small blocks and powder particles by using a manual or hammering machine, and enabling the side length of each side of each small block to be less than 3 mm. And grinding the fine particles and the small blocks into fine powder by a grinding machine.

And 5, grading by adopting a Miller screen, and sieving all the ground fine powder by a 100-mesh sieve, wherein the sieved substance is the red mud radioactive shielding agent.

And (4) determining the apparent density of the red mud radioactive shielding agent obtained in the step (5) to be within the range of 1.5-2.1 g per cubic centimeter through X-ray diffraction analysis and scanning electron microscopy analysis.

And 6, after visible impurities are removed in a piling yard, randomly sampling 50Kg of wet red mud blocks on the upper layer, the middle layer and the lower layer of the red mud pile. The sampled wet red mud cake was triturated, 4 parts by weight of each 1kg of red mud were taken out therefrom, poured into nylon pots, respectively, and tap water and a suspending agent (PEG2000) were added. The weight ratio of the red mud, the tap water and the PEG2000 is 1:2:0.01, namely the weight of the red mud is 1Kg, the weight of the tap water is 2Kg, and the weight of the PEG2000 is 10 g. The grinding medium is tungsten carbide-cobalt hard alloy balls, the diameter of each ball is phi 10, phi 6 or phi 3mm, and the number of each ball is one third. And rolling the nylon tank on a roller lever type mixer at the rotating speed of 40 revolutions per minute for 4 hours to obtain 4 parts of red mud slurry.

And 7, respectively adding the red mud radioactive shielding agent obtained in the step 5 into 4 parts of the red mud slurry to obtain 4 parts of red mud shielding agent mixed slurry. Wherein, the addition amounts of the red mud radioactive shielding agent in 4 parts of the red mud slurry are respectively as follows: 0.5 wt% of red mud, 1.0 wt% of red mud, 1.5 wt% of red mud and 2 wt% of red mud.

And 8, respectively continuing ball milling the 4 parts of the red mud screening agent mixed slurry for 8 hours, stopping the machine, keeping the machine in a nylon tank for 72 hours for precipitation and aging, discharging the material after aging, separating and milling media, and sieving the materials with a 25-mesh sieve to obtain the undersize product which is 4 kinds of wet screening red mud slurry.

And 9, drying the wet shielding red mud in a ventilated oven at 120 ℃ for 10-24 hours until the water content of the red mud reaches 6-8%, and obtaining 4 kinds of dry shielding red mud.

The dried 4 kinds of dry shielding red mud in the form of loose lumps and powder particles are weighed respectively, each kind is weighed 1Kg, the dry shielding red mud is smashed in a mortar without sieving and directly used as a powder sample, and single test values of uranium-238 radioactivity, radium-226 radioactivity, thorium-232 radioactivity and potassium-40 radioactivity are all less than or equal to 200Bq/Kg in national detection standard (GB6566-2010) building material radionuclide limit of limited quantity in Fushan ceramics research institute.

In conclusion, the invention provides a red mud radioactive shielding agent and a method for shielding red mud radioactivity. The red mud radioactive shielding agent is sintered diffusion type powder and comprises metal powder and nonmetal powder. The metal powder includes one or more of lead, barium, bismuth, tungsten, iron, chromium, and nickel. The non-metal powder comprises one or more of boric acid, boron oxide and bismuth oxide. The radioactive level of nuclides of the red mud can be obviously reduced by adding a red mud radioactive shielding agent into the red mud. The red mud radioactive shielding agent with a certain fineness is prepared by adopting a powder metallurgy process through the working procedures of powder mixing, pressing, sintering diffusion, crushing, fine grinding and the like. A certain amount of red mud radioactive shielding agent is added into the red mud slurry, and the dry shielding red mud is obtained after ball milling and drying, so that the radioactive shielding of the electrolytic aluminum solid waste red mud is realized, the national standard radionuclide limit requirement is met, the solid waste red mud can be utilized on a large scale, a green and environment-friendly ecological environment is built, and the harmonious coexistence of human and nature is realized.

As described above, it will be apparent to those skilled in the art that various other changes and modifications can be made based on the technical solution and the technical idea of the present invention, and all such changes and modifications should fall within the protective scope of the appended claims.