Phosphogypsum-based all-solid-waste radiation-proof carbonization-resistant wall filling material and preparation method thereof

Abstract

The application discloses a phosphogypsum-based full-solid-waste radiation-proof carbonization-resistant wall filling material, which is made of the following raw materials in parts by weight: phosphogypsum 50-80 parts, premixed plant waste slurry 20-30 parts, slag 20-30 parts, waste barite slag 30-40 parts, lithium slag 10-20 parts, foaming agent 0.5-1 part, steel fiber 0.2-0.4 part, water reducing agent 3-6 parts, and water 50-70 parts; compared with common radiation-proof wall filling materials, the radiation-proof wall filling material has the advantages of lighter mass, stronger durability, lower cost and environmental protection under the condition of equivalent radiation-proof effect; and comprehensive resource utilization of phosphogypsum, premixed plant waste slurry, waste barite slag, slag and lithium slag is realized, and the problems of serious solid waste storage and high disposal cost are solved.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material and its preparation method. Background Technology

[0002] Phosphogypsum is a byproduct of phosphate chemical processes, particularly generated in large quantities during the decomposition of phosphate rock with sulfuric acid and the extraction of phosphoric acid. Its emissions vary depending on the grade of the phosphate rock, with global production reaching 150-360 million tons annually. Phosphogypsum appears as a light gray, light yellow, or grayish-black powder, primarily composed of CaSO4·2H2O, and contains small amounts of undecomposed phosphate rock, unwashed phosphoric acid, calcium fluoride, iron and aluminum compounds, acid-insoluble substances, organic matter, and various impurities such as radioactive uranium and radium. With the continuous expansion of phosphate chemical production, the storage of phosphogypsum not only occupies large amounts of land but also easily causes air and water pollution. Therefore, the comprehensive utilization and harmless treatment of phosphogypsum has become an important task for the phosphate chemical industry.

[0003] Ready-mixed concrete slurry is a solid waste generated during the concrete production process. It is usually transported to landfills for disposal. A very small number of ready-mixed concrete plants will recycle and precipitate it for reuse. Ready-mixed concrete slurry is often highly alkaline. If it is piled up indiscriminately, it will pollute the environment and damage the ecosystem. It can also be neutralized with acidic substances and then treated, but the disposal cost is high.

[0004] Barite waste residue is the residual material generated during the mining, processing, and utilization of barite. This residue contains a high amount of barium. Lithium slag is the waste residue and tailings generated during lithium resource mining and production. Iron slag is a byproduct of blast furnace ironmaking, and a large amount of iron slag is generated annually in my country. If barite waste residue, lithium slag, and iron slag are not effectively utilized, they will occupy a significant amount of land. Treating these solid wastes as building materials is the most important way to achieve their effective utilization.

[0005] Ordinary concrete is often used as the radiation shielding material for the walls of medical linear accelerator rooms. When the wall thickness is limited, it is difficult to meet the radiation shielding requirements. For decades, the construction of medical radiotherapy rooms and machine rooms has followed the traditional method of large-volume concrete pouring. This method is difficult to obtain barite raw materials, has strict construction standards, is difficult to construct, has a long construction period, high costs, is not easy to dismantle, is immovable, and cannot simultaneously achieve both shielding performance and mechanical properties. Therefore, using solid waste such as phosphogypsum to make radiation-proof wall filling materials can not only solve the above problems, but also is an important way to utilize resources.

[0006] It is of great significance to combine the excellent properties of foamed concrete with the radiation-proof characteristics of phosphogypsum and barite waste to provide effective radiation-proof building materials for specific fields such as nuclear power plants and hospitals. Summary of the Invention

[0007] The purpose of this invention is to provide a phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material and its preparation method. Compared with common radiation-proof wall filling materials, it is lighter, more durable, cheaper, and more environmentally friendly while maintaining the same radiation protection effect. At the same time, it realizes the comprehensive resource utilization of phosphogypsum, premixed plant waste slurry, barite waste residue, slag, and lithium slag, solving the problems of serious solid waste accumulation and high disposal costs.

[0008] To achieve the above objectives, the following technical solution is adopted:

[0009] A phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material is made from the following raw materials in parts by weight: 50-80 parts phosphogypsum, 20-30 parts premixed plant waste slurry, 20-30 parts slag, 30-40 parts barite waste residue, 10-20 parts lithium slag, 0.5-1 part foaming agent, 0.2-0.4 parts steel fiber, 3-6 parts water-reducing agent, and 50-70 parts water.

[0010] According to the above scheme, the phosphogypsum is in its original state, with a water content of 10-20 wt% and a specific surface area > 100 m². 2 / kg, pH value is 1.6-4.8.

[0011] According to the above scheme, the waste slurry from the premixed concrete plant is the waste generated from each production run of the concrete plant, which contains 20-30 wt% water and has a pH value of 11.2-13.5.

[0012] According to the above scheme, the slag is S95 slag with a specific surface area > 350m². 2 / kg.

[0013] According to the above scheme, the barite waste residue is the residual material generated during the barite processing, with a barium sulfate content ≥80wt%, a particle size of 2-15mm, and a mud content of 1.1wt%.

[0014] According to the above scheme, the lithium slag is the waste residue generated during the mining and production of lithium resources. The main chemical components have the following mass percentages: Li2O 0.5~0.6%, Al2O 38.7~10.2%, K2O 3.2~3.8%, Na2O 0.7~0.9%, SiO2 70.5~78.6%, and a moisture content of 15.6%~24.7wt%.

[0015] According to the above scheme, the water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of ≥25%.

[0016] According to the above scheme, the steel fiber is a long straight steel fiber with a tensile strength ≥350MPa and an aspect ratio of 60~65.

[0017] The preparation method of the above-mentioned phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material includes the following steps:

[0018] S1. Mix phosphogypsum, barite waste residue, lithium slag and half water and wet grind to a fineness of 300.

[0019] S2. Add premixed plant waste slurry, slag, steel fiber, water-reducing agent and residual water and stir to mix evenly to make phosphogypsum-based slurry;

[0020] S3. Add the foaming agent to the above phosphogypsum-based slurry and mix well to obtain phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0021] According to the above scheme, in step S1, the mass ratio of the mixture to the zirconia balls is 1:2, the rotation speed is 300 rpm, and the grinding time is 5-8 min.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention utilizes various solid wastes such as phosphogypsum, premixed plant waste slurry, barite slag, and lithium slag to prepare a phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material. The material has a dry density of 600 kg / m³-800 kg / m³, a 28-day compressive strength of 7-12 MPa, a thermal conductivity of 0.12-0.18 W / (mK), and an internal radiation index of I. Ra The external irradiation index Iγ is 0.2, and the intensity loss rate after 28 days of carbonization is 1.5~5%.

[0024] This invention pre-treats phosphogypsum, barite waste residue, and lithium slag using a wet milling process. Direct utilization of these materials is often insufficient to fully realize their potential, and lithium slag typically cannot be used alone as an alkali activator. However, wet milling pre-treatment improves their fineness, allowing them to react fully with premixed slurry from a mixing plant and function together as an alkali activator. The wet milling process effectively refines the particles in phosphogypsum and barite waste residue, resulting in a more uniform distribution. This refinement and homogenization improves their physical and chemical properties, providing better conditions for subsequent applications. This process also increases the fineness of the phosphogypsum and lithium slag slurry, making the gypsum crystals smaller and more evenly distributed in the slurry, increasing density and reducing the average diameter of pores after carbonization, thus improving the carbonization resistance of phosphogypsum and lithium slag.

[0025] By using a mixture of lithium slag and premixed concrete slurry as an alkali activator, the water solubility and usability of phosphogypsum were enhanced. The reaction between lithium slag and phosphogypsum also improved the neutron radiation protection of phosphogypsum, resulting in a lightweight wall filling material with radiation protection and carbonization resistance. When lithium slag and premixed concrete slurry are mixed, the active components such as SiO2 in the lithium slag react with calcium hydroxide and other substances in the slurry to produce hydrated calcium silicate, thus accelerating the hardening process and solving the problem of phosphogypsum's retarded setting. This also improves the early strength and durability of the material. Phosphogypsum contains a large amount of water of crystallization, which is released through the reaction between lithium slag and phosphogypsum, thus moderating fast neutrons. The Li and its compounds in the lithium slag can weaken the penetration intensity of neutron flux and improve carbonization resistance. The high barium sulfate content in the barite waste slag also enhances the material's radiation protection performance. Through multiple mixing methods, both neutron radiation protection and carbonization resistance are improved. Meanwhile, phosphogypsum and lithium slag have densities much lower than cement, which can effectively reduce the bulk density of this material. By adding a foaming agent, a low-density neutron radiation-resistant and carbonization-resistant wall filling material can be prepared.

[0026] The wall filling material of this invention has the characteristics of low density, high heat insulation, radiation protection, carbonization resistance and excellent mechanical properties, providing a new choice of radiation protection building materials for specific fields such as hospitals and nuclear power plants. Detailed Implementation

[0027] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0028] In the specific implementation method, phosphogypsum is used in its original form, with a water content of 10-20 wt% and a specific surface area > 100 m². 2 / kg, pH value is 1.6-4.8.

[0029] The waste slurry from the ready-mixed concrete plant is the waste generated from each production run of the concrete plant. It contains 20-30 wt% water and has a pH value of 11.2-13.5.

[0030] The slag used is S95 slag, with a specific surface area >350m³. 2 / kg.

[0031] Barite waste residue is a residual material generated during the barite processing, with a barium sulfate content ≥80wt%, a particle size of 2-15mm, and a mud content of 1.1wt%.

[0032] The lithium slag used is waste residue generated during the mining and production of lithium resources. The main chemical components by mass percentage are: Li2O 0.5~0.6%, Al2O 38.7~10.2%, K2O 3.2~3.8%, Na2O 0.7~0.9%, SiO2 70.5~78.6%, and moisture content 15.6%~24.7wt%.

[0033] The water-reducing agent used is polycarboxylate water-reducing agent, with a water reduction rate of ≥25%.

[0034] The steel fibers used are long and straight steel fibers with a tensile strength ≥350MPa and an aspect ratio of 60~65.

[0035] Example 1

[0036] In this comparative example, the raw material components and their mixing ratios of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 50, premixed plant waste slurry 20, barite waste slag 30, slag 20, lithium slag 10, steel fiber 0.2, foaming agent 0.5, water-reducing agent 3, and water 50.

[0037] S1. Pretreatment of waste residues such as phosphogypsum and barite: Since the raw phosphogypsum contains a small amount of impurities and moisture and the particles are relatively coarse, it must be pretreated before use. Mix 50 parts of phosphogypsum, 30 parts of barite waste residue, 10 parts of lithium slag, and 25 parts of water and pour them into an ultrafine wet mill. Adjust the mass ratio of the mixture to the zirconia balls to 1:2, rotate at 300 rpm, and grind for 5 minutes to reduce the fineness of the phosphogypsum and barite waste residue.

[0038] S2. Slurry preparation: 20 parts of waste slurry from the premix plant, 20 parts of slag, 0.2 parts of steel fiber, 3 parts of water-reducing agent and 25 parts of water are poured into an ultrafine wet mill and stirred for 3 minutes to prepare phosphogypsum-based slurry.

[0039] S3. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0040] Comparative Example 1

[0041] In this comparative example, the raw material components and their mixing ratios of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 50, premixed plant waste slurry 20, barite waste slag 30, slag 20, lithium slag 10, steel fiber 0.2, foaming agent 0.5, water-reducing agent 3, and water 50.

[0042] S1. Slurry preparation: Pour 50 parts of phosphogypsum, 30 parts of barite waste residue, 20 parts of premixed plant waste slurry, 20 parts of slag, 10 parts of lithium slag, 0.2 parts of steel fiber, 0.5 parts of foaming agent, 3 parts of water-reducing agent and 50 parts of water into a mixer and stir for 8 minutes.

[0043] S2. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0044] Comparative Example 2

[0045] In this comparative example, the raw material components and their mixing ratio of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 50, premixed plant waste slurry 20, barite waste slag 30, slag 20, steel fiber 0.2, foaming agent 0.5, water-reducing agent 3, and water 50.

[0046] S1. Pretreatment of waste residues such as phosphogypsum and barite: Since the raw phosphogypsum contains a small amount of impurities and moisture and the particles are relatively coarse, it must be pretreated before use. Mix 50 parts of phosphogypsum, 30 parts of barite waste residue and 25 parts of water and pour them into an ultrafine wet mill. Adjust the mass ratio of the mixture to the zirconia balls to 1:2, rotate at 300 rpm and grind for 5 minutes to reduce the fineness of the phosphogypsum and barite waste residue.

[0047] S2. Slurry preparation: 20 parts of waste slurry from the premix plant, 20 parts of slag, 0.2 parts of steel fiber, 3 parts of water-reducing agent and 25 parts of water are poured into an ultrafine wet mill and stirred for 3 minutes to prepare phosphogypsum-based slurry.

[0048] S3. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0049] Example 2

[0050] In this comparative example, the raw material components and their mixing ratios of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 60, premixed plant waste slurry 25, barite waste slag 40, slag 25, lithium slag 12, foaming agent 0.7, steel fiber 0.2, water-reducing agent 5, and water 60.

[0051] S1. Pretreatment of waste residues such as phosphogypsum and barite: Since the raw phosphogypsum contains a small amount of impurities and moisture and the particles are relatively coarse, it must be pretreated before use. Mix 60 parts of phosphogypsum, 40 parts of barite waste residue, 12 parts of lithium slag, and 30 parts of water and pour them into an ultrafine wet mill. Adjust the mass ratio of the mixture to the zirconium oxide balls to 1:2, rotate at 300 rpm, and grind for 6 minutes to reduce the fineness of the phosphogypsum and barite waste residue.

[0052] S2. Slurry preparation: 25 parts of waste slurry from the premix plant, 25 parts of slag, 0.2 parts of steel fiber, 5 parts of water-reducing agent and 30 parts of water are poured into an ultrafine wet mill and stirred for 3 minutes to prepare phosphogypsum-based slurry.

[0053] S3. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0054] Example 3

[0055] In this comparative example, the raw material components and their mixing ratios of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 70, premixed plant waste slurry 30, barite waste slag 30, slag 30, lithium slag 15, steel fiber 0.2, foaming agent 0.9, water-reducing agent 6, and water 70.

[0056] S1. Pretreatment of waste residues such as phosphogypsum and barite: Since the raw phosphogypsum contains a small amount of impurities and moisture and the particles are relatively coarse, it must be pretreated before use. Mix 70 parts of phosphogypsum, 30 parts of barite waste residue, 15 parts of lithium slag, and 35 parts of water and pour them into an ultrafine wet mill. Adjust the mass ratio of the mixture to the zirconia balls to 1:2, and grind at 300 rpm for 7 minutes to reduce the fineness of the phosphogypsum and barite waste residue.

[0057] S2. Slurry preparation: 30 parts of waste slurry from the premix plant, 30 parts of slag, 0.2 parts of steel fiber, 6 parts of water-reducing agent and 35 parts of water are poured into an ultrafine wet mill and stirred for 3 minutes to prepare phosphogypsum-based slurry.

[0058] S3. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0059] Example 4

[0060] In this comparative example, the raw material components and their mixing ratio of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material are as follows by weight: phosphogypsum 80, premixed plant waste slurry 25, barite waste slag 35, slag 25, lithium slag 20, steel fiber 0.2, foaming agent 1.0, water-reducing agent 6, and water 70.

[0061] S1. Pretreatment of waste residues such as phosphogypsum and barite: Since the raw phosphogypsum contains a small amount of impurities and moisture and the particles are relatively coarse, it must be pretreated before use. Mix 80 parts of phosphogypsum, 35 parts of barite waste residue, 20 parts of lithium slag, and 35 parts of water and pour them into an ultrafine wet mill. Adjust the mass ratio of the mixture to the zirconia balls to 1:2, the speed to 300 rpm, and grind for 8 minutes to reduce the fineness of the phosphogypsum and barite waste residue.

[0062] S2. Slurry preparation: 25 parts of waste slurry from the premix plant, 25 parts of slag, 0.2 parts of steel fiber, 6 parts of water-reducing agent, and 35 parts of water are poured into an ultrafine wet mill and stirred for 3 minutes to prepare phosphogypsum-based slurry.

[0063] S3. Preparation of filling material: Add foaming agent into the above slurry according to the design ratio and stir for 3 minutes to obtain the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0064] The wall filling materials obtained in the above embodiments and comparative examples were subjected to performance tests, and the test results are shown in Table 1.

[0065] Table 1

[0066]

[0067] Analysis of the test results of the comparative examples and the embodiments shows that:

[0068] A comparison of the data from Example 1 and Comparative Example 1 shows that the preparation method has a significant impact on the 28-day compressive strength, thermal conductivity, and radiation protection performance of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material. The wet grinding treatment with phosphogypsum, barite waste residue, and lithium slag effectively improves the various properties of the phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

[0069] A comparison of the data from Example 1 and Comparative Example 2 shows that lithium slag effectively enhances the neutron penetration resistance of phosphogypsum, and the increase in Li element also improves the anti-carbonization performance.

Claims

1. A phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material, characterized in that... It is made from the following raw materials in parts by weight: 50-80 parts phosphogypsum, 20-30 parts premixed plant waste slurry, 20-30 parts slag, 30-40 parts barite waste residue, 10-20 parts lithium slag, 0.5-1 part foaming agent, 0.2-0.4 parts steel fiber, 3-6 parts water-reducing agent, and 50-70 parts water; the phosphogypsum is in its original state, with a water content of 10-20 wt% and a specific surface area > 100 m². 2 / kg, pH value is 1.6-4.8; the waste slurry from the premixed concrete plant is the waste generated from each production run of the concrete plant, which contains 20-30wt% water and has a pH value of 11.2-13.5; The preparation method of the phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material includes the following steps: S1. Mix phosphogypsum, barite waste residue, lithium slag and half water and wet grind; the mass ratio of the mixture to zirconia balls is 1:2, the rotation speed is 300 rpm, and the grinding time is 5-8 min. S2. Add premixed plant waste slurry, slag, steel fiber, water-reducing agent and residual water and stir to mix evenly to make phosphogypsum-based slurry; S3. Add the foaming agent to the above phosphogypsum-based slurry and mix well to obtain phosphogypsum-based solid waste radiation-proof and carbonization-resistant wall filling material.

2. The phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material as described in claim 1, characterized in that... The slag is S95 slag with a specific surface area >350m². 2 / kg.

3. The phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material as described in claim 1, characterized in that... The barite waste residue is the residual material generated during the barite processing, with a barium sulfate content ≥80wt%, a particle size of 2-15mm, and a mud content of 1.1wt%.

4. The phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material as described in claim 1, characterized in that... The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of ≥25%.

5. The phosphogypsum-based all-solid-waste radiation-proof and carbonization-resistant wall filling material as described in claim 1, characterized in that... The steel fiber is a long, straight steel fiber with a tensile strength ≥350MPa and an aspect ratio of 60~65.

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