Preparation method of radiation-proof mortar based on lead-zinc tailings

Abstract

This application discloses a method for preparing radiation-shielding mortar based on lead-zinc tailings. By crushing and density sorting lead-zinc tailings containing barite, the synergistic effect of high-density and low-density components is rationally utilized. On this basis, functional components such as rare earth tungsten composite oxide powder, boron-containing zirconium complex modifier, calcium aluminate, quasi-crystalline rare earth silicate powder, and graphene oxide dispersion are introduced to construct a radiation-shielding mortar system with high density, multi-energy-level radiation absorption capacity, and excellent mechanical properties. This effectively improves the mortar's attenuation capacity for various types of radiation such as gamma rays and neutron rays. At the same time, the quasi-crystalline structure and the micro-enhancing effect of graphene oxide significantly reduce the internal porosity of the material and improve the interfacial bonding state. Thus, while realizing the high-value utilization of lead-zinc tailings resources, it overcomes the problems of insufficient radiation shielding efficiency, difficulty in balancing mechanical properties and durability, and low level of industrial solid waste utilization in existing radiation-shielding mortars.

Description

Technical Field

[0001] This application belongs to the field of special building materials technology, specifically relating to a method for preparing radiation-shielding mortar based on lead-zinc tailings. Background Technology

[0002] With the rapid development of nuclear energy utilization, radiotherapy, industrial non-destructive testing and space exploration, the requirements for the radiation protection performance of building and engineering materials are increasing. As a functional material that can be directly applied to walls, shielding structures and protective components, radiation-proof mortar has gradually become the focus of research and application in related fields.

[0003] Existing radiation-shielding mortars typically rely on high-density materials such as barite, magnetite, hematite, or lead powder as the main protective phase, enhancing the absorption capacity of high-energy radiation such as gamma rays by increasing the overall density of the material. However, this traditional approach generally suffers from high raw material costs, limited resource availability, poor construction adaptability, and problems such as heavy material weight and susceptibility to segregation. Especially in the context of pursuing green building materials and the resource utilization of solid waste, its sustainability is significantly constrained.

[0004] At the same time, a large number of lead-zinc mines have generated a huge amount of tailings during long-term development. These tailings usually contain a certain proportion of barite and other high-density mineral components, and theoretically have the potential value as aggregates or functional fillers for radiation shielding materials. However, due to factors such as the complex mineral composition of tailings, unreasonable particle size distribution, insufficient activity, and the risk of migration of harmful components, the utilization of lead-zinc tailings in existing technologies is mostly concentrated in low-value-added roadbeds, backfill materials, or simple building materials. Their in-depth application in the field of high-performance radiation shielding materials is still very limited.

[0005] Furthermore, existing research on tailings-based radiation shielding materials largely focuses on simply increasing density or doping with high atomic number elements. It lacks a comprehensive design that considers the control of the material's microstructure, the synergistic effect of radiation absorption mechanisms, and the systematic improvement of mechanical and durability properties. This results in materials often failing to simultaneously meet the requirements of high shielding efficiency, high structural stability, and long-term service reliability in practical applications. In addition, the introduction of large amounts of heavy fillers into traditional cement-based radiation shielding mortars often leads to increased porosity, weakened interfacial transition zones, and early shrinkage cracking, further diminishing their engineering applicability.

[0006] Therefore, how to achieve large-scale and high-value utilization of lead-zinc tailings while constructing a high-performance radiation-proof mortar system through the synergistic construction of multi-scale and multi-functional components has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] One objective of this application is to provide a method for preparing radiation-shielding mortar based on lead-zinc tailings. Through the synergistic design of multiple components and mechanisms, this method addresses the common problems of limited protective efficiency, insufficient structural density, and low utilization level of industrial solid waste in existing radiation-shielding mortars. The resulting radiation-shielding mortar achieves higher levels of adaptability to engineering applications, comprehensive resource utilization, and overall performance, thus realizing a radiation-shielding mortar preparation technology that combines environmental benefits with engineering value.

[0008] To achieve the above objectives, the first aspect of this application provides a method for preparing radiation-shielding mortar based on lead-zinc tailings, comprising the following steps: The lead-zinc tailings containing barite are crushed and then density-sorted to obtain a high-density component A enriched with barite and a low-density component B enriched with silica-alumina minerals. High-density component A and low-density component B are mixed evenly at a mass ratio of (2-4):1 to obtain a mixture; The mixture is mixed with the cementitious material at a mass ratio of (2-5):1 to obtain the matrix material; Additives and water are added sequentially to the matrix material and stirred until a slurry is obtained; The slurry was cured for 7 days at 20±2℃ and relative humidity above 95%. The additives include 3-8 parts of rare earth tungsten composite oxide powder, 1-5 parts of boron-zirconium complex modifier, 5-10 parts of calcium aluminate, 1-3 parts of quasi-crystalline rare earth silicate powder, and 0.1-0.5 parts of graphene oxide dispersion.

[0009] According to a specific embodiment of this application, the rare earth tungsten composite oxide powder is prepared by high-temperature solid-phase reaction of tungsten trioxide with at least two rare earth element oxides, wherein the rare earth elements are any two or more of lanthanum, cerium, neodymium, and yttrium.

[0010] According to a specific embodiment of this application, the molar ratio of tungsten to rare earth elements in the rare earth tungsten composite oxide powder is (1.5-3.5):1.

[0011] According to specific embodiments of this application, the boron-containing zirconium complex modifier is an amorphous solid formed by the complexation of borates, zirconium salts and polyhydroxy organic ligands under weakly alkaline conditions.

[0012] According to a specific embodiment of this application, the polyhydroxy organic ligand is an aromatic polyhydroxy compound with a rigid polycyclic skeleton structure, wherein the aromatic polyhydroxy compound molecule simultaneously contains at least one fused aromatic ring structure and 4-6 hydroxyl groups.

[0013] According to a specific embodiment of this application, the boron-zirconium complex modifier is obtained by complexing borate, zirconium salt and polyhydroxy organic ligand in a water-alcohol mixed solvent system. The alcohol in the water-alcohol mixed solvent is a straight-chain alcohol containing 2-4 carbon atoms.

[0014] According to a specific embodiment of this application, the raw materials of the quasi-crystalline rare earth silicate powder include a silicon source and a rare earth source, wherein the silicon source is selected from one or more of high-purity quartz powder, silica sol or fumed silica, and the rare earth source is selected from one or more of rare earth oxides, rare earth nitrates or rare earth acetates.

[0015] According to specific embodiments of this application, the rare earth element contained in the rare earth source in the quasi-crystalline rare earth silicate powder is one or more of lanthanum, cerium, praseodymium, neodymium, yttrium, or ytterbium.

[0016] According to a specific embodiment of this application, the molar ratio of the rare earth element to the Si element in the silicon source is (0.6-1.8):1.

[0017] According to a specific embodiment of this application, before curing the slurry, the slurry is first subjected to vacuum degassing treatment. The degassing vacuum degree is 0.06-0.09 MPa and the degassing time is 3-10 min, so as to reduce the internal porosity of the mortar and improve its mechanical properties and radiation protection stability.

[0018] Compared with the prior art, the above-described solutions of this application have at least the following beneficial effects: (1) This application crushes and sorts the lead-zinc tailings containing barite, and then mixes the obtained high-density components with low-density components in a specific mass ratio to achieve a good balance between the overall density and the uniformity of the internal structure of the mortar system, thereby providing a stable material basis for radiation attenuation.

[0019] (2) This application further introduces rare earth tungsten composite oxide powder. Tungsten in this powder has a high atomic number and electron density, and has significant absorption and scattering capabilities for high-energy ionizing radiation such as gamma rays. The various rare earth elements have a synergistic effect in terms of energy level structure and radiation cross section, which can broaden the radiation absorption energy spectrum range and avoid the problem of insufficient radiation absorption efficiency of a single high-density material for a specific energy range. At the same time, the unique non-periodic long-range ordered structure of quasi-crystalline rare earth silicate powder makes it exhibit multiple scattering and energy dissipation characteristics under radiation, further extending the radiation propagation path inside the material and improving the effective attenuation capability per unit thickness of the material. Through the synergistic distribution of multiple high atomic number elements and special crystal structure functional phases, the radiation-shielding mortar prepared in this application can achieve a comprehensive protection effect against multiple types of radiation without relying on the large-scale addition of a single heavy metal material, thereby significantly improving the radiation protection efficiency and stability, and overcoming the technical limitations of existing radiation-shielding mortars with single protection effect and efficiency improvement relying on the simple superposition of material density. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 The final test results of the comparative experiment on the performance of radiation-shielding mortar in Experiment Example 1 of this application are shown in the figure. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0023] In the existing technology, radiation-shielding mortar generally suffers from problems such as high cost of radiation-shielding materials, limited raw material sources, heavy environmental burden, difficulty in balancing mechanical properties and radiation-shielding performance, and insufficient long-term service stability. This application substantially solves the contradiction between the low level of tailings resource utilization and the insufficient comprehensive performance of radiation-shielding mortar by sorting, reconstructing and multi-scale functional enhancement of barite-containing lead-zinc tailings.

[0024] First, existing radiation-shielding mortars or concretes typically rely on high atomic number materials such as natural barite, magnetite, hematite, lead powder, or high-purity tungsten and bismuth to achieve shielding against gamma rays, neutrons, or X-rays. These materials are either non-renewable mineral resources with high mining and processing costs, or their addition significantly degrades the mechanical and construction properties of the matrix, and may even introduce potential heavy metal environmental risks. Furthermore, relying solely on high-density materials for "passive absorption" radiation shielding results in large material thickness and quantity requirements, which is detrimental to engineering applications. In addition, the long-term stockpiling of large quantities of lead-zinc tailings not only occupies land and pollutes the environment, but also fails to effectively utilize the barite, silica, and aluminum minerals contained within them. Existing tailings-based materials are mostly limited to low-value-added backfilling or ordinary building materials, making it difficult to meet the performance requirements of high-end radiation shielding projects.

[0025] To address the aforementioned issues, the technical solution of this application first uses crushing and density separation methods to scientifically divide barite-containing lead-zinc tailings into a high-density component A enriched with barite and a low-density component B enriched with silica-alumina minerals, and then blends them according to a specific mass ratio. This design not only avoids the performance unevenness caused by the traditional "full-volume extensive utilization" of tailings, but also achieves the synergistic construction of radiation protection function and mechanical framework by simultaneously introducing a high-density phase and an active silica-alumina phase into the material. The barite enriched in high-density component A can significantly improve the overall linear attenuation coefficient of the mortar, effectively absorbing gamma rays and X-rays, while the silica-alumina minerals in low-density component B can participate in hydration or pozzolanic reactions in the cementing system, optimizing the microstructure and improving density and strength, thus fundamentally solving the problem of declining mechanical properties commonly found in high-density radiation protection materials.

[0026] Building upon this foundation, this application further constructs a multi-mechanism coupled radiation protection and enhancement system by introducing various functional additives, a key innovation rarely addressed in existing technologies. The addition of rare-earth tungsten composite oxide powder not only utilizes the strong gamma-ray absorption capacity brought by tungsten's high atomic number but also improves the scattering and absorption efficiency of high-energy rays through the regulation of the crystal structure and energy level splitting effect of rare-earth elements. This achieves excellent radiation protection effects at relatively low dosages, overcoming the problems of large dosages and poor dispersibility associated with traditional single tungsten trioxide or lead-based fillers. The specific molar ratio design of tungsten to rare-earth elements balances the material's radiation protection performance and compatibility, facilitating its stable existence in cement-based systems.

[0027] The inclusion of a boron-zirconium complex modifier addresses the shortcomings of existing radiation shielding materials in terms of neutron shielding and interfacial stability. Boron possesses excellent absorption capabilities for thermal neutrons, while zirconium exhibits good neutron scattering and structural stabilization effects. Through a complex structure formed by polyhydroxy organic ligands, boron and zirconium are highly dispersed and stable within the mortar matrix, avoiding the defects of traditional borides such as easy dissolution and precipitation. Simultaneously, this complex modifier improves the interfacial bonding between the filler and the cementitious matrix at the microscopic level, reducing interfacial defects and enhancing the overall long-term durability and radiation shielding stability of the material.

[0028] The synergistic introduction of calcium aluminate and quasi-crystalline rare earth silicate powders solves the problems of insufficient early strength, coarse pore structure, and poor long-term stability of tailings-based mortar from the perspective of hydration kinetics and microstructure regulation. Calcium aluminate can react rapidly in the early stage, promoting the formation of hydration products, while quasi-crystalline rare earth silicates, due to their special aperiodic ordered structure and the presence of rare earth elements, can not only fill pores as active fillers, but also scatter and dissipate radiation multiple times at the microscale, significantly improving the radiation protection efficiency per unit thickness of the material. This is a technical effect that is difficult to achieve with traditional crystalline or amorphous fillers.

[0029] Furthermore, the introduction of graphene oxide dispersion enables the mortar system of this application to achieve structural enhancement and functional improvement at the nanoscale. The excellent two-dimensional structure and surface functional groups of graphene oxide can effectively bridge hydration products, refine pore size distribution, and reduce interconnected porosity, thereby significantly improving compressive and flexural strength without increasing material density, and reducing the formation of "penetration channels" for radiation in the pores, thus improving radiation protection stability. This effect is further amplified after vacuum degassing treatment, making the internal structure of the mortar more dense and uniform, overcoming the performance fluctuation problem caused by the large number of pores and defects in traditional radiation-shielding mortars.

[0030] According to a specific embodiment of this application, this application provides a method for preparing radiation-shielding mortar based on lead-zinc tailings, comprising the following steps: The lead-zinc tailings containing barite are crushed and then density-sorted to obtain a high-density component A enriched with barite and a low-density component B enriched with silica-alumina minerals. High-density component A and low-density component B are mixed evenly at a mass ratio of (2-4):1 to obtain a mixture; The mixture is mixed with the cementitious material at a mass ratio of (2-5):1 to obtain the matrix material; Additives and water are added sequentially to the matrix material and stirred until a slurry is obtained; The slurry was cured for 7 days at 20±2℃ and relative humidity above 95%. The additives include 3-8 parts of rare earth tungsten composite oxide powder, 1-5 parts of boron-zirconium complex modifier, 5-10 parts of calcium aluminate, 1-3 parts of quasi-crystalline rare earth silicate powder, and 0.1-0.5 parts of graphene oxide dispersion.

[0031] The radiation-shielding mortar preparation method based on lead-zinc tailings proposed in this application addresses the common technical problems of existing radiation-shielding mortars, such as reliance on natural high-density ores as raw materials, difficulty in achieving comprehensive performance, and low level of industrial solid waste utilization. It constructs an overall solution that uses lead-zinc tailings as the core raw material and achieves performance improvement through structural reconstruction and multi-functional synergy.

[0032] First, this application does not simply use lead-zinc tailings directly as inert aggregate. Instead, through the key pretreatment steps of crushing and density separation, it effectively distinguishes the different mineral compositions in the tailings into a high-density component A enriched with barite and a low-density component B enriched with silica and aluminum minerals. The apparent density of the high-density component A is 4.2-4.8 g / cm³. 3 Within this range, the apparent density of low-density component B is 2.4-2.8 g / cm³. 3 Within a certain range, this fundamentally changes the traditional utilization method of tailings, which is characterized by disordered minerals and uncontrollable properties. The high-density component A, obtained through density sorting, has a high average atomic number and density, providing a good basis for radiation absorption in the mortar system. Meanwhile, the silica-alumina minerals enriched in the low-density component B possess potential pozzolanic activity or filling effects, which are beneficial for participating in the cementitious system reaction and improving the microstructure. By blending the two in a specific mass ratio, the final mortar maintains reasonable mechanical properties and volume stability while possessing high radiation protection capabilities, avoiding the problems of increased brittleness and decreased strength caused by simply increasing density.

[0033] Furthermore, this application mixes the aforementioned mixture with cementitious materials at a specific mass ratio. This ratio ensures a high content of tailings in the system, thereby achieving large-scale utilization of solid waste resources, while the rational introduction of cementitious materials ensures the structural integrity and durability of the mortar after molding, providing a feasible basis for engineering applications. Based on this matrix material, this application also introduces various additives with clearly defined functions into the system. The addition of rare earth tungsten composite oxide powder introduces a highly efficient gamma-ray absorption and scattering mechanism into the mortar, building upon the existing barite protection, achieving a significant improvement in radiation protection performance even at low dosages. The presence of boron-zirconium complex modifier balances neutron shielding capability with interfacial stability, achieving stable dispersion of boron and zirconium elements in the alkaline cement system through the complex structure, avoiding the defects of traditional boron-based materials such as easy loss and poor durability. The introduction of calcium aluminate helps regulate the early hydration reaction process, improves the early strength of the mortar, and improves the structure of hydration products, providing necessary mechanical support for high-dosage tailings systems. Quasi-crystalline rare earth silicate powder utilizes its special aperiodic ordered structure and rare earth element characteristics to generate multiple scattering and energy dissipation of rays at the microscale, while also refining the pore structure as an active or semi-active filler. The addition of a small amount of graphene oxide dispersion plays a bridging, reinforcing, and densifying role at the nanoscale, significantly reducing pore connectivity, thereby simultaneously improving mechanical properties and radiation protection stability.

[0034] As an optional implementation, the rare earth tungsten composite oxide powder is prepared by high-temperature solid-phase reaction of tungsten trioxide with at least two rare earth element oxides, wherein the rare earth elements are any two or more of lanthanum, cerium, neodymium, and yttrium.

[0035] This application specifies that rare earth tungsten composite oxide powder is prepared by high-temperature solid-state reaction of tungsten trioxide with at least two specific rare earth element oxides, wherein the selected rare earth elements are any two or more of lanthanum, cerium, neodymium, and yttrium. In traditional radiation shielding materials, tungsten trioxide is considered an excellent gamma-ray shielding material due to its high atomic number and high density. However, single tungsten trioxide powder is prone to agglomeration in cement-based materials, exhibiting limited interfacial bonding ability. Furthermore, its shielding mechanism against different energy levels of radiation is relatively simple, often requiring high dosages to achieve the desired effect. This not only increases material costs but also adversely affects the fluidity and mechanical properties of mortar.

[0036] Therefore, this application introduces at least two rare earth element oxides and employs a high-temperature solid-state reaction to achieve deep composite formation of tungsten trioxide and rare earth oxides at the lattice scale, thereby constructing a more complex energy level structure within the material that is conducive to radiation attenuation. Rare earth elements such as lanthanum, cerium, neodymium, and yttrium possess unfilled 4f electron shells, and their oxides can generate various electronic transitions and energy dissipation pathways under high-energy radiation. When they form a composite phase with tungsten trioxide, they not only enhance the absorption of gamma rays but also improve the overall shielding efficiency against broad-spectrum radiation through multiple scattering and energy transfer mechanisms. This composite structure, involving multiple rare earth elements, significantly broadens the effective radiation shielding frequency band of the material compared to single rare earth doping or single tungsten trioxide, making the protective effect more stable and durable. Simultaneously, the high-temperature solid-state reaction preparation method ensures the formation of a stable crystalline phase or solid solution structure between the rare earth oxides and tungsten trioxide, preventing the rare earth elements from existing in a simple coating or physical mixing form, thus avoiding potential segregation, dissolution, or performance degradation problems in the alkaline environment of cement. This stable crystal structure allows the mortar to maintain its radiation protection performance over long-term service, solving the technical problem that some existing radiation protection additives show significant degradation over time.

[0037] In addition, the introduction of rare earth elements has improved the particle surface characteristics of tungsten trioxide powder to a certain extent, which enhances the interfacial compatibility between it and the hydration products of cementitious materials. This is conducive to the uniform dispersion of the powder in the matrix, so that a continuous and effective radiation-resistant phase can be formed under low doping conditions, avoiding performance fluctuations caused by local enrichment.

[0038] From the perspective of raw materials, tungsten trioxide is recognized for its excellent absorption and scattering of ionizing radiation such as gamma rays; while rare earth element oxides can be selected from two or more of lanthanum oxide, cerium oxide, neodymium oxide or yttrium oxide. These rare earth oxides not only have high atomic numbers, but also show significant differences in energy level structure, electronic transition characteristics and radiation interaction cross section. By introducing multiple rare earth elements, a more complex and stable energy level structure can be formed inside the material, thereby broadening the response range to radiation in different energy ranges.

[0039] As an optional implementation, the molar ratio of tungsten to rare earth elements in the rare earth tungsten composite oxide powder is (1.5-3.5):1.

[0040] This application further defines the molar ratio range between tungsten and rare earth elements, specifically controlling the molar ratio of tungsten to rare earth elements within (1.5-3.5):1. Tungsten, with its extremely high atomic number and density, is a core contributing element for the efficient absorption of gamma rays and X-rays, and its content directly determines the mass absorption coefficient of the material for high-energy electromagnetic radiation. However, simply increasing the tungsten content, while enhancing radiation absorption, can easily lead to a simple crystal structure, limited internal energy level distribution, insufficient scattering and energy dissipation mechanisms for radiation, and problems such as excessive powder density, poor dispersibility, and decreased compatibility with cementitious matrices. Rare earth elements, on the other hand, play a more significant role in radiation shielding systems through energy level modulation and synergistic scattering. Their unfilled 4f electron orbitals enable the material to generate multiple electron transition paths when excited by radiation, thereby enhancing the multiple scattering and energy attenuation effects of radiation within the material.

[0041] This application controls the molar ratio of tungsten to rare earth elements at (1.5-3.5):1, ensuring that tungsten remains the dominant element in the composite oxide and guaranteeing a sufficiently high linear attenuation capability. Simultaneously, the introduction of appropriate amounts of rare earth elements effectively modulates the tungsten trioxide lattice, forming a multi-level, multi-scattering-center composite structure. This achieves highly efficient shielding against a wide energy spectrum of radiation without significantly increasing the amount of material used. This ratio range allows the absorption and scattering mechanisms to reach an optimal synergistic state, which is a crucial foundation for achieving high radiation shielding efficiency.

[0042] Furthermore, the molar ratio of tungsten to rare earth elements directly affects the types of phases formed, the integrity of the crystal structure, and the distribution of lattice defects during high-temperature solid-state reactions. When the tungsten content is too high and the rare earth content is insufficient, the composite oxide tends to be closer to a single tungsten trioxide phase, and rare earth elements are difficult to fully enter the lattice or exist only in a small amount of doping, thus limiting their control over the crystal structure and performance. Conversely, when the rare earth content is too high and the tungsten content is too low, it is easy to form a multiphase coexistence or a non-ideal solid solution structure, or even generate some independent rare earth oxide phases. This not only weakens the dominant role of tungsten in radiation protection but may also introduce potential structural defects due to differences in the thermal expansion coefficients and chemical stability between different phases. The (1.5-3.5):1 molar ratio range specified in this application is beneficial for forming structurally stable and uniformly composed rare earth tungsten composite oxides under high-temperature solid-state reaction conditions, enabling rare earth elements to effectively enter the tungsten trioxide lattice or form a stable composite crystal phase, thereby ensuring the structural stability and performance consistency of the powder during subsequent mortar preparation and long-term service.

[0043] As an optional implementation, the boron-containing zirconium complex modifier is an amorphous solid formed by the complexation of borates, zirconium salts and polyhydroxy organic ligands under weakly alkaline conditions.

[0044] The radiation-shielding mortar in this application uses lead-zinc tailings containing barite as the main aggregate source. Through density sorting, a high-density component enriched with barite and a low-density component enriched with silica and alumina minerals are obtained. These components work synergistically with various functional components such as cementing materials, rare-earth tungsten composite oxide powder, quasi-crystalline rare-earth silicate powder, and graphene oxide dispersion to construct a multi-scale, multi-mechanism radiation shielding system. In this complex system, relying solely on high atomic number elements for radiation absorption often leads to problems such as insufficient interfacial bonding, easy formation of microcracks, and insufficient long-term service stability. Boron-zirconium complex modifiers are introduced in this context. Through chemical complexation and structural regulation, they form a flexible yet stable "amorphous network phase" within the material, effectively compensating for the shortcomings of traditional radiation-shielding mortars in terms of interface and durability without compromising the strength of the inorganic framework.

[0045] Specifically, the borates described in this application can be sourced from boric acid, borax, or sodium metaborate. These borates readily undergo hydrolysis and structural rearrangement in aqueous solutions, forming compounds containing [B(OH)4]. - Boron can be incorporated into various boron-oxygen structural units, such as [B3O3(OH)3]. Boron plays a crucial role in radiation shielding materials, particularly in neutron radiation shielding, where its high neutron capture cross-section makes it an ideal neutron absorber. Introducing boron into mortar systems in a complexed state, compared to directly adding borides or simple borates, not only avoids the problem of rapid dissolution or migration of boron in alkaline cement systems but also achieves uniform distribution and long-term stable existence of boron within the material through the complex structure.

[0046] Zirconium salts, as another key raw material for boron-zirconium complex modifiers, can be water-soluble or hydrolyzable zirconium salts such as zirconium oxychloride, zirconium nitrate, or zirconium acetate. These zirconium salts readily undergo partial hydrolysis under weakly alkaline conditions, generating Zr-OH structural units with strong coordination capabilities. Zirconium possesses high chemical stability and radiation resistance, and is often used in inorganic materials to improve corrosion resistance, heat resistance, and structural stability. When zirconium salts coexist with borates and polyhydroxy organic ligands, zirconium ions can act as multi-coordination centers, forming stable complex structures with boron-oxygen structures and hydroxyl groups on organic ligands, thereby constructing an amorphous but highly cross-linked organic-inorganic hybrid network.

[0047] The complexation reaction is carried out under weakly alkaline conditions, which is a crucial limitation of this application and is decisive for the formation of the complex structure. If the system is too acidic, the borate mainly exists in an undissociated or oligomeric state, which is not conducive to the formation of stable complexes with zirconium ions and polyhydroxy organic ligands; while if the alkalinity is too strong, it easily leads to the rapid hydrolysis of zirconium salt to form Zr(OH)4 precipitate, destroying the homogeneity of the complex. By controlling the pH of the system within, for example, the range of 8.0-9.5, borate, zirconium salt, and polyhydroxy organic ligands can coexist in solution with suitable reactivity, gradually forming an amorphous complex solid. After drying, this amorphous solid appears as a fine powder or gel-like substance, which is easy to mix uniformly with other inorganic components in the subsequent mortar preparation process.

[0048] From the perspective of material structure and performance, this boron-zirconium complex modifier plays a multi-layered role in radiation-shielding mortar. First, at the microstructural level, this amorphous complex can fill the micropores between lead-zinc tailings aggregates, cement hydration products, and rare-earth tungsten composite oxide particles, reducing the overall porosity of the material and thus reducing multiple scattering paths of radiation within the material, improving shielding efficiency. Second, at the interface level, the organic-inorganic network structure in the complex modifier acts as a "flexible transition phase," alleviating stress concentration between materials of different moduli and inhibiting the generation and propagation of microcracks. This is particularly important for maintaining the structural integrity of the radiation-shielding mortar under long-term radiation and temperature and humidity cycling conditions. Third, at the radiation mechanism level, the absorption of neutron radiation by boron, the scattering of high-energy rays by zirconium, and the synergistic effect of energy dissipation by the organic aromatic structure make this modifier not only a structural modifying component but also a functional radiation protection component.

[0049] More importantly, the boron-zirconium complex modifier exists in an amorphous solid form, with relatively mild chemical properties. It will not undergo violent side reactions with calcium hydroxide or hydrated calcium silicate in the cementitious materials, nor will it adversely affect the structural stability of rare earth tungsten composite oxide powder and quasi-crystalline rare earth silicate powder. On the contrary, its molecular or nanoscale dispersion helps to promote the uniform distribution of graphene oxide dispersion in the system, thereby further improving the compactness and mechanical properties of the mortar on a macroscopic scale.

[0050] As an optional implementation, the polyhydroxy organic ligand is an aromatic polyhydroxy compound with a rigid polycyclic skeleton structure, wherein the aromatic polyhydroxy compound molecule simultaneously contains at least one fused aromatic ring structure and 4-6 hydroxyl groups.

[0051] This application also explicitly defines the structural characteristics of the "polyhydroxy organic ligand," namely, that the polyhydroxy organic ligand is an aromatic polyhydroxy compound with a rigid polycyclic skeleton structure, and that the aromatic polyhydroxy compound molecule simultaneously contains at least one fused aromatic ring structure and 4-6 hydroxyl groups. This facilitates the formation of a stable chelated ring structure. Under weakly alkaline conditions, these hydroxyl groups can be partially deprotonated, reacting with zirconium salts to form Zr. 4+ Alternatively, Zr-OH species may coordinate to form Zr-OC bonds; simultaneously, boron atoms in the borate can also form boronic acid ester structures with ortho-hydroxyl groups, thus achieving multiple synergistic complexation of boron-zirconium-organic ligands on the same organic framework. This multi-site, multi-center complexation mode is difficult to achieve with ordinary small-molecule polyols or simple phenolic compounds.

[0052] From a materials chemistry perspective, the fused aromatic ring structure endows polyhydroxy organic ligands with significant rigidity. This rigidity is inherited in the final boron-zirconium complex modifier and manifests in its internal structural characteristics as an amorphous solid. Compared to flexible chain-like organic ligands, rigid aromatic polycyclic skeletons are less prone to fracture or conformational collapse in alkaline and irradiated environments, which is crucial for the long-term service performance of radiation-shielding mortars. Especially in applications such as nuclear facilities, medical radiation protection, or industrial flaw detection protection, materials often need to maintain structural stability under long-term irradiation conditions. Fused aromatic rings themselves have high radiation tolerance, and their π-conjugated system can disperse radiation energy to a certain extent, mitigating the damage of radiation to the material structure at the molecular level.

[0053] On the other hand, the presence of 4-6 hydroxyl groups gives these polyhydroxy organic ligands extremely strong coordination and cross-linking capabilities in complexation reactions. Multiple hydroxyl groups can form spatially suitable chelating configurations, allowing an organic molecule to simultaneously coordinate with multiple zirconium ions or boron atoms, thereby constructing a three-dimensional cross-linked network at the molecular scale. This network, after drying, exhibits an amorphous solid, lacking a long-range ordered structure, but with highly stable local coordination structures. Simultaneously, this amorphous characteristic also makes the modifier well-suited for use in mortar systems, preventing stress concentration or interfacial debonding due to crystal form differences.

[0054] When this type of boron-zirconium complex modifier is introduced into the radiation-shielding mortar system, its polyhydroxy aromatic skeleton can also generate a certain degree of physical or chemical interaction with cement hydration products. For example, phenolic hydroxyl groups can form weak coordination or hydrogen bonding with calcium ions on the surface of hydrated calcium silicate gel, thereby enhancing interfacial bonding; the aromatic ring structure helps to improve the rigidity and stability of the interfacial region at the microscale. This effect does not disrupt the normal hydration process of the cementitious system, but rather helps to refine the pore structure and reduce the proportion of interconnected pores, thereby macroscopically improving the mechanical properties and impermeability of the mortar.

[0055] In terms of radiation protection performance, these polyhydroxy aromatic ligands also make positive contributions. On the one hand, the boron-zirconium complex structure they participate in forms allows boron to be dispersed in a stable form within the material, effectively exerting neutron absorption. On the other hand, the aromatic fused ring structure itself has a certain energy dissipation capability for high-energy rays, and can produce an additional attenuation effect on radiation through electron cloud polarization and energy transfer mechanisms. When they coexist synergistically with inorganic radiation-protective components such as barite, rare-earth tungsten composite oxides, and quasi-crystalline rare-earth silicates, they can form a radiation protection system with multiple mechanisms superimposed on "absorption-scattering-dissipation," thereby significantly improving the overall protection effect.

[0056] As an optional implementation, the boron-zirconium complex modifier is obtained by complexing borate, zirconium salt and polyhydroxy organic ligand in a water-alcohol mixed solvent system, wherein the alcohol in the water-alcohol mixed solvent is a straight-chain alcohol containing 2-4 carbon atoms.

[0057] This application further refines the process based on the boron-zirconium complex modifier technology. The core of this application is that the reaction environment for the preparation of the boron-zirconium complex modifier is clearly defined. That is, the modifier is obtained by complexing borate, zirconium salt and polyhydroxy organic ligand as raw materials in a water-alcohol mixed solvent system. The alcohols are straight-chain alcohols containing 2-4 carbon atoms.

[0058] This application explicitly employs a water-alcohol mixed solvent system for the complexation reaction. Essentially, this system creates favorable conditions for the formation of a uniform and stable complex structure between borates, zirconium salts, and polyhydroxy organic ligands by adjusting the polarity, solubility, and reaction kinetics of the reaction medium. While a single aqueous system exhibits good solubility for borates and most zirconium salts, it often suffers from limited solubility and insufficient dispersibility for polyhydroxy organic ligands with rigid polycyclic aromatic skeletons. This can easily lead to excessively high local concentrations and uneven complexation reactions, ultimately affecting the structural consistency and performance stability of the modifier. Introducing an appropriate amount of low-carbon straight-chain alcohol as a co-solvent can effectively improve the solubility and dispersion of polyhydroxy aromatic compounds in the reaction system, allowing their molecules to fully participate in the complexation reaction.

[0059] Specifically, the alcohols in the water-alcohol mixed solvent are limited to straight-chain alcohols containing 2-4 carbon atoms, such as ethanol, n-propanol, or n-butanol. These alcohol molecules have moderate polarity, with a hydrophilic hydroxyl group at one end and a hydrophobic alkyl chain at the other, enabling them to act as "molecular bridges" in the aqueous phase. On the one hand, ethanol or n-propanol can form a homogeneous mixture with water without introducing phase separation problems; on the other hand, they can interact with polyhydroxy organic ligands through hydrogen bonding, reducing the π-π stacking tendency between ligand molecules and thus improving their dispersion uniformity in the system.

[0060] In this water-alcohol mixed solvent system, the borate raw material can be a common inorganic boron source such as boric acid, borax, or sodium metaborate. These borates have good solubility in the aqueous phase and can form various boron-oxygen structural units that can participate in complexation under weakly alkaline conditions. When ethanol or n-propanol is introduced into the system, the solubility and hydrolysis equilibrium of the borates are not disrupted, but the reaction pathway for forming boronic acid ester structures with polyhydroxy organic ligands becomes milder and more controllable, which is conducive to the formation of structurally homogeneous complex intermediates.

[0061] Zirconium salt raw materials can include zirconium oxychloride, zirconium nitrate, or zirconium acetate, all of which exhibit good solubility and dispersion in water-alcohol mixtures. Under weakly alkaline conditions, zirconium salts undergo moderate hydrolysis, generating highly coordinated Zr-OH or Zr... 4+ Complexation centers. A water-alcohol mixed solvent effectively inhibits the excessively rapid hydrolysis and precipitation of zirconium salts, allowing zirconium ions to participate in the synergistic complexation reaction with polyhydroxy organic ligands and borates in a milder and more controllable manner, thus avoiding the formation of coarse, structurally heterogeneous zirconium hydroxide precipitates. This is particularly crucial for ultimately obtaining boron-containing zirconium complex modifiers in an "amorphous solid" form.

[0062] From the perspective of reaction mechanism, in the water-alcohol mixed solvent system, polyhydroxy organic ligand molecules can exist in a relatively extended conformation. Their multiple hydroxyl groups can form polydentate coordination structures with zirconium ions or stable borate ester bonds with borates. This multiple complexation gradually builds a three-dimensional cross-linked network at the molecular scale, and the presence of alcohol molecules helps to regulate the reaction rate, preventing the network from agglomerating or separating too quickly during its formation, thus ultimately yielding a solid product with a uniform structure, highly cross-linked internally, but an overall amorphous state.

[0063] This boron-zirconium complex modifier, obtained in a water-alcohol mixed solvent system, exhibits excellent system compatibility in the subsequent preparation of radiation-shielding mortar. On the one hand, its amorphous characteristics and organic-inorganic hybrid structure enable it to be uniformly dispersed in the matrix when mixed with lead-zinc tailings aggregates, cementitious materials, and rare earth tungsten composite oxide powders, without causing local weak interfaces due to differences in crystal form or particle size. On the other hand, its internal stable boron-zirconium-organic complex structure makes it difficult for boron and zirconium elements to migrate or degrade in alkaline cement systems, thus enabling them to continuously play a role in neutron absorption, radiation scattering, and structural stabilization throughout the entire life cycle of the material.

[0064] As an optional implementation, the raw materials for the quasi-crystalline rare earth silicate powder include a silicon source and a rare earth source, wherein the silicon source is selected from one or more of high-purity quartz powder, silica sol, or fumed silica, and the rare earth source is selected from one or more of rare earth oxides, rare earth nitrates, or rare earth acetates.

[0065] As an optional implementation, the rare earth element contained in the rare earth source in the quasi-crystalline rare earth silicate powder is one or more of lanthanum, cerium, praseodymium, neodymium, yttrium, or ytterbium.

[0066] As an optional implementation, the molar ratio of the rare earth element to the Si element in the silicon source is (0.6-1.8):1.

[0067] As an optional implementation, before curing the slurry, the slurry is first subjected to vacuum degassing treatment with a degassing vacuum degree of 0.06-0.09 MPa and a degassing time of 3-10 min, in order to reduce the internal porosity of the mortar and improve its mechanical properties and radiation protection stability.

[0068] Example 1 I. Raw Material Selection and Preparation Lead-zinc tailings: Lead-zinc tailings discharged from a lead-zinc mine were selected as raw materials. Their main mineral composition includes barite, quartz, feldspar, and a small amount of calcite. The lead-zinc tailings were mechanically crushed to ensure their particle size met the requirements for subsequent sorting, and then set aside for use.

[0069] Rare earth tungsten composite oxide powder Tungsten source: Tungsten trioxide; Rare earth source: Lanthanum oxide and cerium oxide are selected; The molar ratio of tungsten to rare earth elements is 1.5:1.

[0070] Tungsten trioxide, lanthanum oxide and cerium oxide were thoroughly mixed and placed in a high-temperature furnace. The mixture was calcined at 1200°C for 3 hours and then naturally cooled before being pulverized to obtain rare earth tungsten composite oxide powder with uniform particle size.

[0071] Boron-zirconium complex modifier Boron source: borax; Zirconium source: Zirconium oxychloride; Polyhydroxy organic ligands: Anthraquinone polyhydroxy organic ligands, which have a fused aromatic ring structure and contain 4 hydroxyl groups in the molecule; Solvent system: Water-ethanol mixed solvent, wherein ethanol is a straight-chain alcohol containing 2 carbon atoms.

[0072] Borax, zirconium oxychloride, and a polyhydroxy organic ligand were added to a water-ethanol mixed solvent. The pH of the system was adjusted to 8.5 under weakly alkaline conditions, and the reaction was carried out at 60°C with stirring for 4 hours. After the reaction was completed, an amorphous solid product was obtained. The obtained product was dried and pulverized to obtain a boron-zirconium complex modifier.

[0073] Calcium aluminate: Select calcium aluminate powder with a particle size not exceeding 200 mesh.

[0074] Quasi-crystalline rare earth silicate powder Silicon source: High-purity quartz powder with a particle size of less than 10μm; Rare earth source: Lanthanum oxide; The molar ratio of rare earth elements to silicon is 0.6:1.

[0075] High-purity quartz powder was thoroughly mixed with lanthanum oxide, ball-milled, and then placed in a high-temperature furnace and calcined at 1000°C for 2 hours. Subsequently, it was rapidly cooled to obtain quasi-crystalline rare earth silicate powder.

[0076] Graphene oxide: Single-layer graphene oxide microflakes with an average particle size of 2-5 μm are selected.

[0077] cementing materials Ordinary silicate cement was selected as the cementing material.

[0078] II. Preparation Steps Step 1: Density separation of tailings The crushed lead-zinc tailings were controlled to have a particle size of less than 3 mm and were separated using a heavy medium density separation method. Based on the difference in mineral density, a high-density component A enriched in barite and a low-density component B enriched in silica-alumina minerals were obtained and collected separately for later use.

[0079] Step 2: Mixing of high-density and low-density components The high-density component A and the low-density component B are added to a mixing device at a mass ratio of 2:1 and mixed evenly to obtain a tailings mixture.

[0080] Step 3: Preparation of matrix materials The tailings mixture is mixed with cementitious materials at a mass ratio of 2:1 to obtain the matrix material.

[0081] Step 4: Preparation of graphene oxide dispersion Graphene oxide microflakes were added to deionized water and treated with ultrasonic dispersion for 10 minutes to obtain a uniform and stable graphene oxide dispersion.

[0082] Step 5: Ingredients and Mixing Weigh out each ingredient according to the following proportions and add them to the planetary mixer: Based on 100 parts of cementitious material, add: Rare earth tungsten composite oxide: 3 parts Boron-zirconium complex modifier: 1 part Calcium aluminate: 5 parts Quasicrystalline rare earth silicates: 1 part Graphene oxide dispersion: 0.1 parts Water: 40 parts Stir at low speed for 3 minutes, then stir at high speed for 5 minutes to obtain a slurry.

[0083] First, stir at low speed for 3 minutes, then stir at high speed for 5 minutes to fully mix the components and obtain a uniform and fine mortar.

[0084] Step 6: Vacuum degassing The obtained slurry was placed in a vacuum degassing device and degassed for 3 minutes under a vacuum of 0.06 MPa to remove internal air bubbles.

[0085] Step 7: Maintenance The deaerated slurry is injected into a mold and cured for 7 days in an environment with a temperature of 20±2℃ and a relative humidity of not less than 95%. After curing, radiation-proof mortar based on lead-zinc tailings is obtained.

[0086] Example 2 I. Raw Material Selection and Preparation Lead-zinc tailings: Lead-zinc tailings discharged from a lead-zinc mine were selected as raw materials. Their main mineral composition includes barite, quartz, feldspar, and a small amount of calcite. The lead-zinc tailings were mechanically crushed to ensure their particle size met the requirements for subsequent sorting, and then set aside for use.

[0087] Rare earth tungsten composite oxide powder Tungsten source: Tungsten trioxide; Rare earth sources: Lanthanum oxide, cerium oxide, and neodymium oxide were selected; The molar ratio of tungsten to rare earth elements is 3.5:1.

[0088] After thoroughly mixing tungsten trioxide with the above-mentioned rare earth oxides, the mixture was placed in a high-temperature furnace and calcined at 1200°C for 3 hours. After natural cooling, it was pulverized to obtain rare earth tungsten composite oxide powder.

[0089] Boron-zirconium complex modifier Boron source: borax; Zirconium source: Zirconium oxychloride; Polyhydroxy organic ligands: Anthraquinone polyhydroxy organic ligands, which have a fused aromatic ring structure and contain 6 hydroxyl groups in the molecule; Solvent system: Water-n-butanol mixed solvent, wherein n-butanol is a straight-chain alcohol containing 4 carbon atoms.

[0090] Borax, zirconium oxychloride, and a polyhydroxy organic ligand were added to a water-n-butanol mixed solvent. The pH of the system was adjusted to 8.5 under weakly alkaline conditions, and the reaction was carried out at 60°C with stirring for 4 hours. After the reaction was completed, an amorphous solid product was obtained. The product was dried and pulverized to obtain a boron-zirconium complex modifier.

[0091] Calcium aluminate: Select calcium aluminate powder with a particle size not exceeding 200 mesh.

[0092] Quasi-crystalline rare earth silicate powder Silicon source: silica sol; Rare earth source: yttrium oxide; The molar ratio of rare earth elements to silicon is 1.8:1.

[0093] The silica sol and yttrium oxide were mixed evenly according to the set molar ratio, and after pretreatment, the mixture was placed in a high-temperature furnace and calcined at 1000°C for 2 hours. Then, it was rapidly cooled to obtain quasi-crystalline rare earth silicate powder.

[0094] Graphene oxide: Single-layer graphene oxide microflakes with an average particle size of 2-5 μm are selected.

[0095] cementing materials Ordinary silicate cement was selected as the cementing material.

[0096] II. Preparation Steps Step 1: Density separation of tailings The crushed lead-zinc tailings were controlled to have a particle size of less than 3 mm and were separated using a heavy medium density separation method. Based on the difference in mineral density, a high-density component A enriched in barite and a low-density component B enriched in silica-alumina minerals were obtained and collected separately for later use.

[0097] Step 2: Mixing of high-density and low-density components The high-density component A and the low-density component B are added to a mixing device at a mass ratio of 4:1 and mixed thoroughly to obtain a tailings mixture.

[0098] Step 3: Preparation of matrix materials The tailings mixture is mixed with cementitious materials at a mass ratio of 5:1 to obtain the matrix material.

[0099] Step 4: Preparation of graphene oxide dispersion Graphene oxide microflakes were added to deionized water and treated with ultrasonic dispersion for 30 min to obtain a uniform and stable graphene oxide dispersion.

[0100] Step 5: Ingredients and Mixing Based on 100 parts of cementitious material, add: Rare earth tungsten composite oxide powder: 8 parts; Boron-zirconium complex modifier: 5 parts; Calcium aluminate: 10 parts; Quasicrystalline rare earth silicate powder: 3 parts; Graphene oxide dispersion: 0.5 parts; Water: 42 portions.

[0101] First, stir at low speed for 3 minutes, then stir at high speed for 5 minutes to fully mix the components and obtain a uniform and fine mortar.

[0102] Step 6: Vacuum degassing The obtained slurry was placed in a vacuum degassing device and degassed for 10 minutes under a vacuum of 0.09 MPa to fully remove air bubbles from the slurry.

[0103] Step 7: Maintenance The deaerated slurry is injected into a mold and cured for 7 days in an environment with a temperature of 20±2℃ and a relative humidity of not less than 95%. After curing, radiation-proof mortar based on lead-zinc tailings is obtained.

[0104] Example 3 I. Raw Material Selection and Preparation Lead-zinc tailings: Lead-zinc tailings discharged from a lead-zinc mine were selected as raw materials. Their main mineral composition includes barite, quartz, feldspar, and a small amount of calcite. The lead-zinc tailings were mechanically crushed to ensure their particle size met the requirements for subsequent sorting, and then set aside for use.

[0105] Rare earth tungsten composite oxide powder Tungsten source: tungsten trioxide; Rare earth sources: lanthanum oxide and neodymium oxide; The molar ratio of tungsten to rare earth elements is 2.75:1.

[0106] After thoroughly mixing tungsten trioxide with the above-mentioned rare earth oxides, the mixture was placed in a high-temperature furnace and calcined at 1050°C for 2.5 hours. After natural cooling, it was pulverized to obtain rare earth tungsten composite oxide powder.

[0107] Boron-zirconium complex modifier Boron source: borax; Zirconium source: Zirconium oxychloride; Polyhydroxy organic ligands: Anthraquinone polyhydroxy organic ligands, which have a fused aromatic ring structure and contain 5 hydroxyl groups in the molecule; Solvent system: Water-n-butanol mixed solvent.

[0108] Borax, zirconium oxychloride, and a polyhydroxy organic ligand were added to a water-n-butanol mixed solvent. The pH of the reaction system was adjusted to 8.0 under weakly alkaline conditions, and the mixture was stirred at 50°C for 3 hours to allow boron and zirconium to undergo a complexation reaction with the polyhydroxy organic ligand. After the reaction was complete, a complex product was obtained. The obtained product was dried and pulverized to obtain a boron-zirconium complex modifier.

[0109] Calcium aluminate: Select calcium aluminate powder with a particle size not exceeding 200 mesh.

[0110] Quasi-crystalline rare earth silicate powder Silicon source: silica sol; Rare earth source: yttrium oxide; The molar ratio of rare earth elements to silicon is 1.5:1.

[0111] After uniformly mixing silica sol and yttrium oxide, the mixture was calcined at 900°C for 1.5 hours, followed by rapid cooling to obtain quasi-crystalline rare earth silicate powder.

[0112] Graphene oxide: Graphene oxide microflakes with an average particle size of 2-5 μm are selected.

[0113] cementing materials Ordinary silicate cement was selected as the cementing material.

[0114] II. Preparation Steps Step 1: Density separation of tailings The lead-zinc tailings were crushed and screened to make the particle size less than 2 mm. The heavy medium density separation method was used to separate the high-density component A and the low-density component B.

[0115] Step 2: Mixing of tailings components High-density component A and low-density component B are mixed at a mass ratio of 3:1 to obtain a tailings mixture.

[0116] Step 3: Preparation of matrix materials The tailings mixture was mixed with cementitious materials at a mass ratio of 3.5:1 to obtain the matrix material.

[0117] Step 4: Preparation of graphene oxide dispersion A stable graphene oxide dispersion was obtained by adding graphene oxide to deionized water and treating it with ultrasonic dispersion for 20 min.

[0118] Step 5: Ingredients and Mixing Based on 100 parts of cementitious material, add: Rare earth tungsten composite oxide powder: 6 parts; Boron-zirconium complex modifier: 3.5 parts; Calcium aluminate: 8 parts; Quasicrystalline rare earth silicate powder: 2 parts; Graphene oxide dispersion: 0.3 parts; Water: 45 portions.

[0119] Stir at low speed for 3 minutes, then stir at high speed for 5 minutes to obtain a uniform slurry.

[0120] Step 6: Vacuum degassing The slurry was placed in a vacuum degassing device and degassed for 8 minutes under a vacuum of 0.07 MPa.

[0121] Step 7: Maintenance The deaerated slurry was injected into a mold and cured for 7 days at 20±2℃ and relative humidity ≥90% to obtain radiation-proof mortar based on lead-zinc tailings.

[0122] Experiment Example 1: Comparative Experiment on the Performance of Radiation-Shielding Mortar I. Experimental Objective By comparing the radiation-shielding mortars prepared in Examples 1, 2, and 3 of this application with existing radiation-shielding mortars in terms of mechanical properties, gamma-ray shielding performance, neutron absorption performance, and structural density, the superior technical effect of the technical solution of this application in terms of comprehensive performance is verified.

[0123] II. Experimental Sample Setup Sample A: Radiation-shielding mortar prepared using the method in Example 1 Sample B: Radiation-shielding mortar prepared using the method in Example 2 Sample C: Radiation-shielding mortar prepared using the method in Example 3 Comparative Sample D (existing technology): uses ordinary silicate cement as cementing material, barite sand as the main radiation-shielding aggregate, and does not contain rare earth tungsten composite oxide, boron-zirconium complex modifier, quasi-crystalline rare earth silicate powder and graphene oxide dispersion. The remaining preparation conditions are consistent with those of Sample AC.

[0124] III. Experimental Methods (I) Sample preparation process Each group of mortar slurry was injected into the standard test mold.

[0125] After injection molding is completed, the mold is placed in a vacuum degassing device and degassed according to the vacuum degree and time corresponding to each embodiment to eliminate internal bubbles.

[0126] After degassing, place the mold in a curing environment with a temperature of 20±2℃ and a relative humidity of ≥95% for 7 days of static curing.

[0127] After the curing period, the samples are demolded and used for subsequent performance testing.

[0128] (II) Compressive Strength Test Method Place the cured specimen between the upper and lower pressure plates of the pressure testing machine, aligning the stress-bearing surface of the specimen with the center of the pressure plate.

[0129] The sample is continuously loaded at a constant loading rate until it fails.

[0130] Record the maximum load value at which the specimen fails.

[0131] The compressive strength is calculated based on the area of ​​the sample subjected to pressure.

[0132] Three parallel specimens were tested for each group of samples, and the average value was taken as the compressive strength result of the mortar in that group.

[0133] (III) Test methods for gamma-ray shielding performance The radiation source is fixed to one end of the testing device.

[0134] Each group of mortar samples with a thickness of 20 mm was placed sequentially between the radiation source and the detector.

[0135] First, the initial intensity I0 of the radiation was measured under conditions without a sample.

[0136] Then, under the same conditions, the intensity I1 of the radiation after passing through the sample was measured.

[0137] Calculate the gamma-ray shielding efficiency using the formula: ; Each group of samples was tested three times, and the average value was taken.

[0138] (iv) Neutron absorption performance testing methods Each group of mortar samples was processed into plate-shaped samples with a uniform thickness.

[0139] The sample is placed in the thermal neutron beam testing device, and the neutron beam passes through the sample perpendicularly.

[0140] The initial neutron flux N0 was measured under sample-free conditions.

[0141] After the sample is placed in the sample, the transmitted neutron flux N is measured.

[0142] The neutron absorption rate is calculated using the following formula: ; Each sample group was tested three times, and the average value of the results was taken.

[0143] (v) Porosity testing methods Dry the cured mortar sample to constant weight and record its dry weight.

[0144] The sample is placed in a mercury porosimeter, and under gradually increasing pressure, mercury is gradually introduced into the pores of the sample.

[0145] The pore size distribution inside the sample is calculated based on the mercury intrusion volume under different pressures.

[0146] The total porosity is calculated based on the sample volume to evaluate the density of the mortar's internal structure.

[0147] The final test results are as follows Figure 1 As shown.

[0148] Therefore, by Figure 1 Experimental results show that the radiation-shielding mortar prepared in the embodiments of this application is significantly superior to the comparative sample in terms of compressive strength, gamma-ray shielding performance, neutron absorption capacity and structural density, demonstrating the synergistic enhancement effect of the multifunctional filler system.

[0149] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0150] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing radiation-shielding mortar based on lead-zinc tailings, characterized in that, Includes the following steps: The lead-zinc tailings containing barite are crushed and then density-sorted to obtain a high-density component A enriched with barite and a low-density component B enriched with silica-alumina minerals. High-density component A and low-density component B are mixed evenly at a mass ratio of (2-4):1 to obtain a mixture; The mixture is mixed with the cementitious material at a mass ratio of (2-5):1 to obtain the matrix material; Additives and water are added sequentially to the matrix material and stirred until a slurry is obtained; The slurry was cured for 7 days at 20±2℃ and relative humidity above 95%. The additives include 3-8 parts of rare earth tungsten composite oxide powder, 1-5 parts of boron-zirconium complex modifier, 5-10 parts of calcium aluminate, 1-3 parts of quasi-crystalline rare earth silicate powder, and 0.1-0.5 parts of graphene oxide dispersion.

2. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 1, characterized in that, The rare earth tungsten composite oxide powder is prepared by high-temperature solid-phase reaction of tungsten trioxide with at least two rare earth element oxides, wherein the rare earth elements are any two or more of lanthanum, cerium, neodymium, and yttrium.

3. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 2, characterized in that, The molar ratio of tungsten to rare earth elements in the rare earth tungsten composite oxide powder is (1.5-3.5):

1.

4. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 1, characterized in that, The boron-containing zirconium complex modifier is an amorphous solid formed by the complexation of borates, zirconium salts and polyhydroxy organic ligands under weakly alkaline conditions.

5. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 4, characterized in that, The polyhydroxy organic ligand is an aromatic polyhydroxy compound with a rigid polycyclic skeleton structure, wherein the aromatic polyhydroxy compound molecule simultaneously contains at least one fused aromatic ring structure and 4-6 hydroxyl groups.

6. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 4, characterized in that, The boron-zirconium complex modifier is obtained by complexing borate, zirconium salt and polyhydroxy organic ligand in a water-alcohol mixed solvent system. The alcohol in the water-alcohol mixed solvent is a straight-chain alcohol containing 2-4 carbon atoms.

7. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 1, characterized in that, The raw materials for the quasi-crystalline rare earth silicate powder include a silicon source and a rare earth source, wherein the silicon source is selected from one or more of high-purity quartz powder, silica sol, or fumed silica, and the rare earth source is selected from one or more of rare earth oxides, rare earth nitrates, or rare earth acetates.

8. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 7, characterized in that, The rare earth element contained in the rare earth source of the quasi-crystalline rare earth silicate powder is one or more of lanthanum, cerium, praseodymium, neodymium, yttrium, or ytterbium.

9. A method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 8, characterized in that, The molar ratio of the rare earth element to the Si element in the silicon source is (0.6-1.8):

1.

10. The method for preparing radiation-shielding mortar based on lead-zinc tailings according to claim 1, characterized in that, Before curing the slurry, the slurry is first subjected to vacuum degassing treatment with a vacuum degree of 0.06-0.09 MPa and a degassing time of 3-10 min, in order to reduce the internal porosity of the mortar and improve its mechanical properties and radiation protection stability.

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