CN111056789A

CN111056789A - A kind of solidification method of radioactive waste residue

Info

Publication number: CN111056789A
Application number: CN201911269377.6A
Authority: CN
Inventors: 洪昌寿; 陈逸凡; 刘永; 罗明亮; 李熙琪; 兰明; 李向阳; 汪弘; 余修武; 李苏哲; 陈艳
Original assignee: University of South China
Current assignee: University of South China
Priority date: 2019-12-11
Filing date: 2019-12-11
Publication date: 2020-04-24
Anticipated expiration: 2039-12-11
Also published as: CN111056789B

Abstract

The present invention provides a method for solidifying radioactive waste residue, comprising the following steps: S1. pulverizing the radioactive waste residue to be treated into slag; S2. mixing the slag with functional filler and cement uniformly to obtain a mixture; S3. Add into sodium silicate or water glass to obtain an aqueous solution of sodium silicate, and then add inorganic acid to obtain acidified water glass; S4. Add PVA into water at a preset temperature, and dissolve to obtain a PVA solution; S5. Combine the mixture with all The acidified water glass and the PVA solution are evenly mixed to obtain a castable, and then the castable is casted and cured to obtain a cement solidified waste slag bag. The invention utilizes the curing and film-forming effects of PVA and the filling effect of active silica gel in acidified water glass, thereby significantly improving the strength and water resistance of the cured body, reducing the porosity of the cured body, thereby increasing the ion diffusion resistance and making the core The diffusion and exudation rate of primary ions is significantly reduced.

Description

Method for solidifying radioactive waste residues

Technical Field

The invention belongs to the technical field of radioactive waste residue treatment, and particularly relates to a method for solidifying radioactive waste residue.

Background

Radioactive waste residues can be classified into low-level radioactive waste residues, medium-level radioactive waste residues and high-level radioactive waste residues according to radioactivity level. The radioactive waste residues are low-level waste residues and medium-level waste residues generated by nuclear industrial mining and smelting. In China, uranium mines and hydrometallurgy plants (hydrometallurgy plants) are built since the 50 th century, and a great amount of radioactive waste residues are reserved in gangue dumps of the uranium mines and tailing dams of the hydrometallurgy plants. The corrosivity and radioactivity of the radioactive waste residues can threaten the health of human bodies and bring harm to the ecological environment. Therefore, how to safely and reliably dispose of radioactive waste residues has become a major research topic throughout the world.

Currently, geological disposal is generally adopted for disposing radioactive waste residues, and the radioactive waste residues need to be solidified before the geological disposal. Common curing methods include cement curing, asphalt curing, ceramic curing, moldingCuring cement, which is a process in which cement reacts with active ingredients in the slag and functional filler to produce gelation, and the slag containing harmful substances is coated and gradually hardened, and the structure of the cured body is mainly 3 CaO. SiO produced by hydration reaction of cement₂The grains of the waste slag are wrapped among the crystals. Therefore, even if the cured body is broken or crushed and immersed in water, the leachability of harmful substances can be reduced. The cement solidification method has the advantages of being particularly effective in treating waste containing heavy metals, simple in solidification process and equipment, low in equipment and operation cost, cheap and easily available in cement raw materials and additives and the like, and the produced solidified body can meet the requirements of GB14569.1 'Cement solidified body required by performance of low and medium level radioactive solidified body'. Therefore, cement curing is the most common curing method in radioactive waste curing treatment. However, the following problems still exist in the current cement curing treatment:

(1) sufficient cement must be added to make the cement solidified body have enough strength, but the sufficient cement can heat up and expand the solidified body due to heat release in the process of hydration and setting, so that the strength of the solidified body after cooling is reduced and cracks appear; (2) in order to delay the heat release and temperature rise in the cement curing process, functional fillers such as fly ash, blast furnace slag, kaolin and the like are usually required to be added, so that the volume and the cost are increased, and the large-scale treatment of radioactive waste residues is difficult to adapt; (3) in order to realize the workability and the gelling property of cement, enough water must be added, the common water-cement ratio is not less than 0.45, so that a cement solidified body has porous interconnected pores, and the leaching rate of nuclides in the cement solidified body is high; (4) due to differences of radioactive waste residue composition, physical and chemical characteristics, components and the like, the cement formula is difficult to adapt to waste residue treatment of different waste residue types and compositions; (5) some special cements affect the long-term storage stability of cement cured bodies due to the characteristics of high heat release speed, large heat release amount and concentration, and are not suitable for large-volume cured bodies.

A cement solidification treatment method for mature radioactive wastes is based on a radioactive waste cement solidification system of American West House, and utilizes cement, an alkali activator, a functional filler and the like to solidify the radioactive wastes. But similar cured bodies all have the problems of low package capacity, higher cost, complex process and the like.

For example, in the patent of the invention with the application publication number of CN110232981A, namely a method for solidifying and treating the cement of radioactive waste, the formula of a solidified body is that the mass ratio of cement, waste resin, lime, an additive and a modifier is 150: 45-55: 4-6: 0.1: 40-60 percent, the volume package capacity of the boron-containing waste resin is increased from about 25 percent to 29 percent, the localization and the generalization of cement required by the solidification of a nuclear power plant are realized, and the purchasing and storing cost is saved to a great extent. But the dosage of the cement in the formula is about 3 times of that of the waste resin, the content is still relatively low, and the cost is high; the solidification body is designed aiming at waste resin, the cement mixing amount is large, the solidification body is only suitable for small-volume solidification, and the solidification requirements of a large amount of radioactive wastes such as slag, tailings and the like are difficult to adapt.

Therefore, there is an urgent need to develop and research a better method for solidifying radioactive waste residues, which can overcome the above problems.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method for solidifying radioactive waste residues, which is characterized in that a PVA solution and acidified water glass are added on the basis of conventional cement solidifying ingredients. The curing and film-forming functions of PVA and the filling function of active silica gel are utilized to improve the strength and water resistance of a cured body and reduce the porosity of the cured body, thereby increasing the ion diffusion resistance and reducing the diffusion and leaching rate of nuclide ions to realize mechanical curing; meanwhile, nuclide ions in the waste residue react with hydration products such as active silica gel, free alumina, calcium oxide and the like to generate new minerals in the hydration and hardening process of the cement so as to realize chemical solidification.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for solidifying radioactive waste residues comprises the following steps:

s1, crushing waste residues: crushing radioactive waste residues to be treated into crushed residues;

s2, mixing the ingredients: uniformly mixing the crushed slag with the functional filler and the cement to obtain a mixture;

s3, acidifying water glass: adding water into sodium silicate or water glass according to a preset mass ratio to obtain a sodium silicate aqueous solution, and then adding inorganic acid to acidify the sodium silicate aqueous solution to obtain acidified water glass;

s4, preparing a PVA solution: adding PVA into water at a preset temperature according to a preset mass ratio, and dissolving to obtain a PVA solution;

s5, performing coagulation casting: and uniformly mixing the mixture with the acidified water glass and the PVA solution to obtain a castable, and then pouring and maintaining the castable to obtain the cement solidified body waste slag ladle.

Further, in step S3, the modulus of the sodium silicate or water glass is > 1.5.

Furthermore, the mass ratio of the water to the sodium silicate solution or the water glass is 1: (0.5 to 3).

Further, in step S3, the inorganic acid is one or both of sulfuric acid and phosphoric acid.

Further, in step S4, the preset temperature is 25 to 95 ℃, and the preset mass ratio of PVA to water is (2:98) - (15: 85).

Further, in step S2, the functional filler includes, but is not limited to, one or more of activated clay, kyanite, sillimanite, andalusite, silica fume, steel slag powder, fly ash, and granulated blast furnace slag powder, and the content of the functional filler with a particle size of less than 0.075mm is greater than 95%; the cement is ordinary portland cement with the strength grade of more than or equal to 42.5.

Further, in step S2, the functional filler includes at least activated clay.

Further, in step S2, the mass ratio of the slag, the functional filler and the cement is 100: (10-50): (10-50).

Further, in step S5, the mass ratio of the mixture, sodium silicate, PVA and water in the castable is 100: (1-4): (0.05-1.00): (15-25).

Further, in step S5, the pouring and curing specifically includes: pouring the casting material into a mold, removing the mold after curing, and then performing standard maintenance for more than 21 days.

Further, in step S1, the radioactive waste residue includes, but is not limited to, slag, tailings, slurry or incineration ash containing radioactive components; the particle size of the crushed slag is less than or equal to 15 mm.

Advantageous effects

Compared with the prior art, the method for solidifying the radioactive waste residue provided by the invention has the following beneficial effects:

(1) the method for solidifying the radioactive waste residues selects PVA to improve the performance of a solidified body on the basis of conventional cement solidification ingredients. However, since PVA has repeated water absorption softening and water loss curing properties, the stability of the resulting cement cured product is poor if only PVA is added. Therefore, the invention neutralizes the sodium silicate aqueous solution with sulfuric acid or phosphoric acid to obtain the acidified water glass containing sodium sulfate or sodium phosphate and silica gel. Wherein, sodium sulfate or sodium phosphate can be used as a curing agent of PVA, and PVA and sodium sulfate or sodium phosphate do not absorb water and soften any more after undergoing irreversible curing; meanwhile, the secondary reactive silica gel not only has high reaction activity, but also has filling effect on the solidified body gap, thereby improving the strength of the solidified body.

(2) According to the method for solidifying the radioactive waste residues, the strength of a solidified body is obviously improved, the porosity of the solidified body is reduced, and the pore structure is improved by utilizing the solidifying action of PVA and the filling action of active silica gel in acidified water glass, so that the ion diffusion resistance is increased, the diffusion and seepage rate of nuclide ions is obviously reduced, and mechanical solidification is realized; on the basis, the cement hydration product and the functional filler have the adsorption effect on nuclide ions, and the nuclide ions are retained in the hydration product to realize adsorption and solidification; meanwhile, nuclide ions in the waste residue react with hydration products such as active silica gel, free alumina, calcium oxide and the like to generate new minerals in the hydration and hardening process of the cement so as to realize chemical solidification. Through the multiple curing effects of mechanical curing, adsorption curing and chemical curing, the cement cured body has the advantages of high strength and low leaching rate.

(3) The invention reduces the porosity of the solidified body and improves the water resistance of the solidified body through the solidifying and film forming effects of PVA.

(4) The method for solidifying the radioactive waste residues, provided by the invention, is only added with a PVA (polyvinyl alcohol) and acidified water glass solidification system on the basis of a conventional cement solidification method, and has the advantages of simple solidification method, strong repeatability and good solidification effect. Therefore, the method has high universality and can be used for treating radioactive slag, smelting slag containing radioactive components, waste filter media (waste activated carbon, zeolite and the like), slurry, incineration ash and the like generated in uranium mines.

Drawings

FIG. 1 is a schematic flow chart of a method for solidifying radioactive waste residues provided by the invention.

Detailed Description

The technical solutions of the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

Referring to fig. 1, the method for solidifying radioactive waste residue provided by the present invention includes the following steps:

before radioactive waste residues are treated by the method, the treated waste residues are confirmed to contain no oxidant (such as hydrogen peroxide, persulfate, nitrate and the like), and if the waste residues contain the oxidant, reduced iron powder is added according to a stoichiometric theoretical value to eliminate the influence. Before crushing the waste residue, if the radioactive waste residue to be treated contains more free water, dehydration or drying is carried out in advance until the water content is less than 5 wt% so as to be suitable for crushing.

the functional filler comprises but is not limited to one or more of activated clay, kyanite, sillimanite, andalusite, silica fume, steel slag powder, fly ash and granulated blast furnace slag powder, and the content of the functional filler with the particle size of less than 0.075mm is more than 95 percent; the cement is ordinary portland cement with the strength grade of more than or equal to 42.5. It is generally preferred that the functional filler comprises activated clay, as activated clay helps to improve the resistance of the cured body to leaching.

the inorganic acid is preferably sulfuric acid, after the sulfuric acid and sodium silicate are subjected to neutralization reaction, sodium sulfate and silica gel are generated, and the sodium sulfate and PVA can be subjected to irreversible solidification, so that the repeated water absorption and water loss characteristics of the PVA are eliminated; the silica gel can fill the gap of the solidified body, and the strength of the solidified body is improved.

S4, preparing a PVA solution: adding PVA into an aqueous solution at a preset temperature according to a preset mass ratio, and dissolving to obtain a PVA solution;

It should be noted that the present invention does not exclude the use of additives such as water reducing agents, air entraining agents, etc., and the use of additives may be advantageous for improving the durability and water resistance of the cured body, but may reduce the strength, water resistance, etc. of the cured body when the additives are not used properly. Therefore, the amount of the admixture to be incorporated should be determined by experiments in accordance with the requirements of the cured body.

The present invention will be further described with reference to specific examples and comparative examples.

Example 1

In the embodiment, uranium ore slag in Hunan province is taken as a sample, and the sample is 0-300 mm gangue.

Solidifying the sample according to the following steps to obtain a cement solidified body:

s1, crushing waste residues: before crushing, firstly airing a slag sample until the moisture content is 3.6 wt%, and then crushing the slag into crushed slag with the granularity of 0-5 mm by using a jaw crusher, wherein the granularity is unselected continuous gradation;

s2, mixing the ingredients: selecting common Portland cement with the strength grade of 52.5, taking activated clay and fly ash in a mass ratio of 1:2 as a functional filler, wherein the content of the functional filler with the particle size of less than 0.075mm is more than 95%, and mixing the crushed slag, the functional filler and the cement in a mass ratio of 70: 15: 15, mixing, stirring and mixing uniformly to obtain a mixture;

s3, acidifying water glass: selecting liquid sodium silicate (water glass) with the mark LGY402 and the modulus of 3.20-3.40, wherein the technical parameters are shown in table 1, and under the stirring condition, firstly, according to the mass ratio of the water glass to tap water of 1:1 to obtain a sodium silicate aqueous solution, and mixing the sodium silicate aqueous solution with 10% sulfuric acid according to a mass ratio of 1:1, mixing to obtain acidified water glass;

TABLE 1 Water glass technical parameters

Liquid sodium silicate	°Bé％(20℃)	Na₂O(wt％)	SiO₂(wt％)	Water-insoluble substance (wt%)	Modulus of elasticity
						LGY402	39.0～40.0	≥8.3	≥26.5	0.80	3.20～3.40
LGY403	39.0～40.0	≥8.2	≥26	——	3.20～3.40

S4, preparing a PVA solution: selecting 100-27H-brand instant polyvinyl alcohol (PVA instant glue yarn), wherein physicochemical parameters are shown in table 2, adding 95 parts of water into a container, heating to 55-60 ℃, starting a stirrer, keeping rotating at a slow speed of 100-150 r/min, adding 5 parts of PVA, stirring and dispersing, continuing stirring, and heating to 90-95 ℃ to completely dissolve the PVA;

TABLE 2 physicochemical parameters of PVA

S5, performing coagulation casting: the mass ratio of the mixture, sodium silicate, PVA and water is 100: (1-4): (0.05-1.00): (15-25), according to the water content in the acidified water glass and the PVA, and the mass ratio of the mixture to the acidified water glass to the PVA solution is 85: 10: 5, proportioning, uniformly stirring, pouring into a mold, carrying out wet curing with the mold for 1 day, removing the mold, and carrying out standard curing for 27 days to obtain a waste residue cement cured body.

Example 2

In the embodiment, the leaching slag of a uranium mine water treatment plant in Hunan is taken as a sample, the granularity of the sample is 0-1.0 mm, and the water content is 8-15%.

s1, crushing waste residues: before crushing, firstly spreading leaching residues to be 10-20 mm thick, drying for 2 hours at 100-105 ℃, and then dispersing the leaching residues into crushed residues by using a ball mill;

s2, mixing the ingredients: selecting common Portland cement with the strength grade of 52.5, taking activated clay, fly ash and granulated blast furnace slag powder with the mass ratio of 1:1:1 as functional filler, wherein the content of the functional filler with the particle size of less than 0.075mm is more than 95%, and the weight ratio of crushed slag to functional filler to cement is 65: 20: 15, mixing, stirring and mixing uniformly to obtain a mixture;

s3, acidifying water glass: selecting liquid sodium silicate (water glass) with the mark LGY403 and the modulus of 3.20-3.40, wherein the technical parameters are shown in table 1, and under the stirring condition, firstly, according to the mass ratio of the water glass to tap water of 2: 1 to obtain a sodium silicate aqueous solution, and mixing the sodium silicate aqueous solution with 15% dilute sulfuric acid according to a mass ratio of 1:1, mixing to obtain acidified water glass;

s4, preparing a PVA solution: this step is substantially the same as step S4 of embodiment 1;

s5, performing coagulation casting: the mass ratio of the mixture, sodium silicate, PVA and water is 100: (1-4): (0.05-1.00): (15-25), according to the water content in the acidified water glass and the PVA, mixing the mixture, the acidified water glass and the PVA solution in a mass ratio of 80: 10: 10, uniformly stirring, pouring into a mold, carrying out wet curing with the mold for 1 day, removing the mold, and carrying out standard curing for 27 days to obtain a waste residue cement cured body.

Examples 3 to 11

Examples 3 to 11 are different from example 1 in that the preparation conditions are shown in table 3, and the others are substantially the same as example 1 and are not repeated herein.

TABLE 3 preparation conditions of examples 3 to 12

Comparative example 1

The solidification method of radioactive waste residue provided in comparative example 1 is different from that of example 1 in that, in step S5, the acidified water glass is replaced with water in equal amount, that is, the mass ratio of the mixture, water and PVA solution is 85: 10: 5, proportioning, uniformly stirring, pouring into a mold, carrying out wet curing with the mold for 1 day, removing the mold, and carrying out standard curing for 27 days to obtain a waste residue cement cured body. The rest is basically the same as embodiment 1, and is not described herein again.

Comparative example 2

The solidification method of radioactive waste residue provided in comparative example 2 is different from that of example 2 in that, in step S5, the PVA solution is replaced with water in equal amount, that is, the mixture, the acidified water glass and the water are mixed in a mass ratio of 80: 10: 10, uniformly stirring, pouring into a mold, carrying out wet curing with the mold for 1 day, removing the mold, and carrying out standard curing for 27 days to obtain a waste residue cement cured body. The rest is basically the same as embodiment 1, and is not described herein again.

Comparative example 3

The solidification method of radioactive waste residue provided in comparative example 3 is different from that of example 2 in that activated clay is not added in step S2, that is: selecting common Portland cement with the grade of 52.5, and mixing the fly ash and the granulated blast furnace slag powder according to the mass ratio of 1: 1' is a functional filler, and the mass ratio of the slag, the functional filler and the cement is 65: 20: 15, mixing, stirring and mixing uniformly to obtain a mixture. The rest is basically the same as embodiment 1, and is not described herein again.

TABLE 4 Performance test results of cement cured bodies

Note: the sequence of the performance test is as follows: compressive strength-impact resistance-soaking resistance-freeze-thaw resistance-leaching resistance, and the subsequent tests are not performed under the condition that the former tests are unqualified or not ideal.

The properties of the solidified waste sludge cements obtained in examples 1 to 11 and comparative examples 1 to 3 were measured according to GB14569.1 to 2011 and the documents cited therein, and the results are shown in table 3. From example 1, it can be seen that the waste slag cement solidified body added with PVA and acidified water glass has high compressive strength, impact resistance, leaching resistance, soaking resistance and freeze-thaw resistance, meets the requirement of GB14569.1 Cement solidified body which is the requirement of the performance of low and medium level radioactive solidified body, and the cement solidified body waste slag bag can meet the requirement of the near-surface treatment standard of radioactive waste slag in China. And when the acidified water glass is not added in the comparative example 1, the compressive strength, the soaking resistance and the freeze-thaw resistance are all obviously reduced, which shows that the addition of the acidified water glass is beneficial to the solidification of PVA and can fill the gaps of the solidified body, thereby improving the strength of the solidified body.

As can be seen from the test results of comparative example 2, the impact resistance of the cement cured body to which no PVA was added could not be achieved.

From the test results of comparative example 3, it can be seen that the leaching resistance of the cement cured body to which activated clay is not added is significantly reduced, indicating that the addition of activated clay contributes to the effect of improving the leaching resistance of the cement cured body.

From the test results of examples 3 to 11, it can be seen that:

1. the sodium silicate with a proper amount can promote solidification of a solidified body and improve the density of the solidified body. The strength, leaching resistance and freeze-thaw resistance of the solidified body are reduced along with the reduction of the addition amount of the solid; however, if the sodium silicate is added too much, the local solidification is too fast, and the impact resistance requirement is difficult to achieve.

PVA has the function of improving the toughness of the solidified body. If the addition amount is too low, the effect is not obvious, and the impact resistance of the cement solid can not meet the standard requirement; if the amount is too high, the compressive strength is remarkably reduced.

3. The cement has obvious influence on the strength of a solidified body. If the addition amount is too low, the strength requirement of the solidified body is difficult to meet; however, when the amount of the additive is large, it is not economical and the inclusion ratio of the cured product is lowered.

4. In example 11, when the water glass is acidified by adding phosphoric acid, the obtained cement solidified body also has good compressive strength, impact resistance and soaking resistance, which are equivalent to those of example 1, but the cost of phosphoric acid is relatively high, and at present, the market price of phosphoric acid is five times of the price of sulfuric acid, so that the sulfuric acid is generally preferred as the acidification raw material of the water glass in practical application by comprehensively considering the practical production demand and the production cost.

In conclusion, on the basis of the conventional cement curing ingredients, the PVA and the acidified water glass are added, the curing and film forming effects of the PVA and the filling effect of the active silica gel in the acidified water glass are utilized, the strength and the water resistance of a cured body are obviously improved, the porosity of the cured body is reduced, the ion diffusion resistance is increased, and the diffusion and leaching rate of nuclide ions is obviously reduced.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. a solidification method of radioactive waste residue, is characterized in that, comprises the following steps:

S1. Waste residue crushing: crushing the radioactive waste residue to be processed into slag;

S2. Mixing of ingredients: mix the slag with functional fillers and cement evenly to obtain a mixture;

S3. Acidified water glass: add water to sodium silicate or water glass according to a preset mass ratio to obtain an aqueous solution of sodium silicate, and then add inorganic acid to acidify it to obtain acidified water glass;

S4. Preparation of PVA solution: according to the preset mass ratio, add PVA into water of preset temperature, and dissolve to obtain PVA solution;

S5. Concrete casting: mix the mixture with the acidified water glass and PVA solution uniformly to obtain a castable, and then cast and maintain the castable to obtain a cement solidified waste slag bag.

2 . The method for solidifying radioactive waste residues according to claim 1 , wherein, in step S3 , the modulus of the sodium silicate or water glass is greater than 1.5. 3 .

3 . The method for solidifying radioactive waste residues according to claim 1 , wherein, in step S3 , the inorganic acid is one or both of sulfuric acid or phosphoric acid. 4 .

4 . The method for solidifying radioactive waste residues according to claim 1 , wherein, in step S4 , the preset temperature is 25-95° C. 5 .

5. The method for solidifying a radioactive waste residue according to claim 1, wherein in step S2, the functional fillers include but are not limited to activated clay, kyanite, sillimanite, andalusite, silicon One or more of ash, steel slag powder, fly ash and granulated blast furnace slag powder; the content of the functional filler with a particle size of less than 0.075mm is greater than 95%; the cement is ordinary silicic acid with a strength grade of ≥42.5 salt cement.

6 . The method for solidifying radioactive waste residues according to claim 5 , wherein, in step S2 , the functional filler at least comprises activated clay. 7 .

7 . The method for solidifying radioactive waste residues according to claim 1 , wherein, in step S2 , the mass ratio of the residues, functional fillers and cement is 100: (10～50): (10～50 . 8 . 50).

8. The method for solidifying a radioactive waste residue according to claim 1, wherein in step S5, the mass ratio of the mixture, sodium silicate, PVA and water in the castable is 100: (1～ 4): (0.05～1.00): (15～25).

9. The solidification method of a kind of radioactive waste residue according to claim 1, is characterized in that, in step S5, the concrete steps of described pouring and curing are: pour the castable into the mold, after curing, remove the mold, then Standard curing more than 21 days.

10. The method for solidifying radioactive waste residues according to claim 1, wherein in step S1, the radioactive waste residues include but are not limited to slag, tailings, mud or incineration ash containing radioactive components; The particle size of the slag is less than or equal to 15mm.