Roadbed stabilizing material taking inorganic solid waste as raw material and preparation method of roadbed stabilizing material

Abstract

The invention belongs to the technical field of road engineering materials, and particularly relates to a roadbed stabilizing material with inorganic solid waste as a raw material and a preparation method thereof.The preparation method comprises the following steps that a composite drying agent is prepared, specifically, acrylic acid is cross-linked to obtain a gel block, the gel block and gravity separation metal tailing powder are stirred and crushed together, and the composite drying agent is obtained after drying and smashing; preparing a material A: slurrying flotation metal tailings, then adjusting the pH value, adding slurry PAM, dehydrating, and uniformly stirring with a composite drying agent to obtain the material A; preparing a material B: preparing the material B from steel slag powder, diammonium hydrogen phosphate and a slag powder curing agent; the material A and the material B are mixed, water is added, and the roadbed stabilizing material with the inorganic solid waste as the raw material is prepared. On the basis of the characteristics of the metal tailings prepared by different processes, good dispersion of the polyacrylic acid super absorbent resin is realized in combination with the process, and the roadbed stabilizing material with low energy consumption and high stability is obtained.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, and in particular relates to a roadbed stabilizer made from inorganic solid waste and its preparation method. Background Technology

[0002] Using solid waste materials plus inorganic cementing materials to replace clay as roadbed material is a way to achieve resource recycling and reduce costs. However, commonly used solid waste materials, such as metal tailings, especially flotation metal tailings, have fine particle sizes and require a lot of energy to dry. At the same time, their composition is complex, and residual sulfur and chlorine elements can slowly affect the overall performance through corrosion and other effects. In addition, the dispersibility problem between solid waste materials and inorganic cementing materials can lead to severe roadbed cracking. Therefore, practical low-cost application still faces certain difficulties.

[0003] CN108083667B discloses a roadbed filler, providing a filler mainly composed of alkali slag and lignin sulfonate. Lignosulfonate is used as a dispersant to improve the mixing uniformity of the alkali slag and reduce its moisture content, thereby improving construction efficiency and compaction effect. However, the alkali slag used in this technical solution is of a single component and does not fully consider the compatibility and synergistic effects between different types of solid waste materials, which may lead to insufficient durability and crack resistance of the roadbed filler in complex environments.

[0004] CN107056157B discloses a roadbed filling material, proposing a material with Xigeda soil and vanadium-titanium tailings as the main components. The combination of these two materials improves the strength and load-bearing capacity of the fill material while achieving effective utilization of waste resources. However, this technical solution does not specify the particle size, pH value, and harmful element content of the vanadium-titanium tailings, which may lead to inconsistent roadbed performance due to significant differences in raw materials during practical applications. Furthermore, while the problem of Xigeda soil disintegrating upon contact with water is somewhat alleviated by adding vanadium-titanium tailings, it does not fundamentally solve the cracking risk caused by water retention, and it does not address the optimization design of the microporous structure, making it difficult to meet the high requirements for roadbed stability under complex working conditions.

[0005] As can be seen from the above, existing technologies also rarely address the problem of the large amount of energy consumed in drying solid waste materials. Furthermore, using wet solid waste materials under the current technological background can lead to inaccurate batching, unstable performance, and problems such as cracking. Summary of the Invention

[0006] In view of this, the present invention provides a roadbed stabilizer material made from inorganic solid waste and its preparation method. Based on the characteristics of metal tailings produced by different processes, and combined with the process, good dispersion of polyacrylic acid superabsorbent resin is achieved, resulting in a roadbed stabilizer material with low energy consumption and high stability.

[0007] To address the above problems, the present invention mainly provides the following technical solutions: On the one hand, the present invention provides a method for preparing roadbed stabilizer material using inorganic solid waste as raw material, comprising the following steps by weight: Includes the following steps: (1) Preparation of gel block: Add 100 parts of acrylic acid to 80-100 parts of water, stir evenly, add 0.5-0.8 parts of initiator, react at 60-65℃ for 1.5-2.5h, add 1-3 parts of crosslinking agent, and continue to react at 60-65℃ for 1.5-2.5h to obtain gel block of polyacrylic acid super absorbent resin; (2) Preparation of composite desiccant: 50-150 mesh gravity separation metal tailings powder is added to the gel block and stirred, crushed, dried and further crushed to obtain composite desiccant; wherein, the mass ratio of the gel block and the gravity separation metal tailings powder is 1:30-40, the moisture content of the composite desiccant is less than 0.5% and the average particle size is 10-20μm; (3) Preparation of slurry: The flotation metal tailings are subjected to pulping treatment to obtain slurry; the solid mass ratio of the slurry is 10-15%, and the pH value is 8-10; (4) Preparation of filter cake: Add 0.1-0.3 ppm of PAM by weight of the slurry to the slurry for dehydration treatment to obtain a filter cake with a moisture content of 12-18%; (5) Preparation of material A: Under stirring conditions, filter cake and composite desiccant are mixed at a mass ratio of 1:1-1.2, followed by densification, settling and dispersion treatment to obtain material A; (6) Preparation of material B: 10-20 parts of steel slag powder, 0.3-1 parts of diammonium hydrogen phosphate and 5-10 parts of slag powder curing agent are dry ball milled and densified to obtain material B; (7) Preparation of roadbed stabilizer: Mix 30-50 parts of material A and 30-50 parts of material B, add 8-15 parts of water, stir evenly, and obtain roadbed stabilizer.

[0008] In step (1), the free radical polymerization and cross-linking reaction of acrylic monomers generate a three-dimensional network of polyacrylic acid superabsorbent resin gel, which achieves efficient water absorption through the ionization of carboxyl groups on the molecular chain and the effect of ion osmotic pressure. In step (2), the introduction of gravity separation metal tailings powder not only solves the engineering problem of the gel being difficult to dry and crush as a dispersion carrier, but also inhibits the excessive swelling of the gel after water absorption through the supporting effect of the rigid inorganic particles of gravity separation metal tailings powder, thereby enhancing its dimensional stability in the subsequent cured body, and also enabling the polyacrylic acid superabsorbent resin gel block to be evenly dispersed in the roadbed material.

[0009] In step (3), the flotation metal tailings are pulped and the pH is adjusted to create an alkaline precipitation environment for the metal ions on their surface. In step (4), anionic PAM is added to capture fine particles and free ions by bridging and flocculation, forming a pretreated filter cake. In step (5), the mixing and densification with the composite desiccant is a key interface engineering process, which makes the composite desiccant particles uniformly embedded in the microstructure of the tailings filter cake, initially forming a prefabricated composite with tailings as the skeleton and containing reversible water-absorbing units, namely material A.

[0010] In step (6), the surface energy of steel slag powder and slag powder increases and the lattice defects increase under the mechanical activation of ball milling. Together with the phosphate ions provided by diammonium hydrogen phosphate, they form a potential alkaline-activated curing system (material B).

[0011] Finally, in step (7), when materials A and B are mixed and water is added and stirred, the hydration activity of the steel slag powder in material B reacts with the free calcium oxide in the steel slag powder, promoting the formation of hydration gel products of the steel slag powder. The specific reaction is as follows: PO4 3- +CaO→CaHPO4 SiO2 + Ca(OH)2 → CaSiO3 The composite desiccant pre-dispersed in material A reduces bleeding and promotes hydration by absorbing excess mixing water. Furthermore, it regulates the internal humidity of the roadbed by absorbing and releasing water during subsequent environmental humidity changes, thus inhibiting the formation of shrinkage cracks. Ultimately, the highly absorbent polyacrylic acid resin is uniformly dispersed in the roadbed material, forming a stable composite whole, thereby meeting the comprehensive requirements of roadbed materials for strength, durability, and environmental adaptability.

[0012] Preferably, in step (1), the initiator is ammonium persulfate and the crosslinking agent is dicumyl peroxide.

[0013] Preferably, in step (2), the gravity separation metal tailings powder is one or more of iron tailings, molybdenum tailings, and tungsten tailings.

[0014] Preferably, the chloride ion content of the gravity separation metal tailings powder is ≤0.3%, and the sulfide content is ≤0.5%.

[0015] Iron, molybdenum, and tungsten tailings originate from gravity separation processes. Their common characteristic is a relatively simple mineral composition, primarily consisting of stable silicate or oxide minerals such as quartz, feldspar, garnet, molybdenite, and scheelite / wolfonite, with a stable crystal structure and strong surface chemical inertness. This chemical inertness is crucial, ensuring that the tailings particles do not release large amounts of soluble ions. Strict limits on the content of harmful impurities represent a forward-looking design for the long-term durability and environmental compatibility of the entire material system. Controlling chloride ion content fundamentally eliminates the risk of electrochemical corrosion of surrounding metal components in the humid environment of the roadbed. Limiting sulfide (as S ions) content to ≤0.5% prevents its gradual oxidation to sulfuric acid under the influence of moisture and oxygen, which could cause acidic hydrolysis of the superabsorbent polyacrylic acid resin molecular chains and sulfate erosion of the cementitious components in the system, leading to material strength deterioration and expansion cracking. This ensures the volume stability and long-lasting performance of the roadbed stabilizer throughout its service life. The particles of gravity separation metal tailings powder are relatively coarse, and the moisture content is easy to control at a low level, below 2%. Furthermore, in this invention, step (2) requires hot air drying to obtain dehydrated polyacrylic acid superabsorbent resin. During this process, the gravity separation metal tailings powder provides a good dispersible skeleton for polyacrylic acid superabsorbent resin, which is beneficial for efficient dehydration.

[0016] Preferably, in step (2), the further pulverization process is as follows: the dried material is pulverized to an average particle size of 10-20 μm by air jet pulverization, and a nitrogen protective atmosphere is maintained during the pulverization process.

[0017] Airflow pulverization utilizes high-speed airflow to impart extremely high kinetic energy to particles, achieving efficient crushing through intense collisions and friction between particles. It boasts high energy utilization and eliminates grinding media contamination, making it particularly suitable for efficiently preparing polyacrylic acid superabsorbent resin / tailings composites with varying degrees of brittleness into powders with a concentrated particle size distribution. This specific particle size range ensures that the composite desiccant particles are uniformly dispersed in the roadbed matrix during subsequent use, forming numerous uniformly distributed micro-nano water storage units, thereby optimizing its water absorption and release behavior and stress distribution. Using nitrogen as the pulverizing medium and maintaining a protective atmosphere completely eliminates the potential explosive environment that may arise from the mixing of high-concentration organic dust and air during pulverization and transportation. Inertization treatment continuously controls the oxygen concentration below the limiting oxygen concentration, fundamentally eliminating the risk of dust explosions. Furthermore, the nitrogen atmosphere effectively isolates oxygen, preventing oxidative degradation of the polyacrylic acid superabsorbent resin molecular chains on newly formed surfaces and under high mechanical energy input conditions, avoiding the failure of its active functional groups such as carboxyl groups, thus maximizing the preservation of the composite desiccant's functional integrity and long-term chemical stability.

[0018] Preferably, in step (3), the flotation metal tailings are one or more of copper tailings, lead-zinc tailings, or fluorite tailings of 180-220 mesh.

[0019] Preferably, the flotation metal tailings have a chloride ion content ≤0.5%, a sulfide content ≤1.0%, and a free calcium oxide content ≤4.0%.

[0020] Flotation processes typically control the particle size at around 200 mesh. Too fine a mesh leads to mud formation, affecting flotation yield, while too coarse a mesh results in poor capture of target minerals, also impacting efficiency. However, refining to 200 mesh inevitably involves mud formation. The average particle size of flotation metal tailings is fine, making drying difficult. Furthermore, since flotation reagents require pH adjustment for optimal flotation, the pH of flotation metal tailings is not stable. This invention fully considers this issue. After flotation metal tailings are processed through methods such as pressure filtration, the water content is between 10-20%. This invention does not require controlling the water content of the flotation metal tailings. The initial pulping treatment of the flotation metal tailings addresses its unstable pH, adjusting the pH to a controllable range. Since most chlorides are water-soluble, the pulping and dewatering processes remove a large amount of chloride ions. The particle size range ensures that the flotation metal tailings particles have a sufficiently large specific surface area, allowing for good particle packing with steel slag and slag powder in the B material, reducing porosity and providing a physical framework for the final dense roadbed structure. The filter press process has low energy consumption. After filtration, the filter cake is mixed with the composite desiccant, and the residual moisture in the filter cake is mainly absorbed by the polyacrylic acid superabsorbent resin in the composite desiccant. The free calcium oxide (f-CaO) content is limited to ≤4.0% to address the delayed volume expansion problem caused by its later hydration. This reaction produces calcium hydroxide, which increases in volume and generates huge expansion stress inside the material, leading to cracking and structural loosening. Strictly controlling its content is one of the keys to ensuring the volume stability of the roadbed.

[0021] Preferably, in step (5), the stirring conditions are 500-800 rpm; the densification process is extrusion or rolling; and the settling time is 30-60 min.

[0022] The material is densified by extrusion or rolling, which allows the composite desiccant to fully contact the pretreated metal tailings powder particles. The temperature during aging and settling is 40-50℃, mainly to allow the composite desiccant to adsorb the moisture on the surface of the metal tailings powder particles.

[0023] Preferably, in step (6), the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area ≥ 400 m². 2 / kg, wherein the free calcium oxide content of the steel slag powder is ≤3.0%.

[0024] The B material in this scheme uses industrial steel slag powder as the main material. In this field, steel slag powder refers to blast furnace slag after steelmaking, not pulverized steel or its products. After grinding and sieving, it yields a material with a specific surface area of ​​350-400 m². 2 The process primarily increases the specific surface area of ​​the steel slag powder (approximately 0.5 kg / kg), essentially acting as an activation agent. An activator is added to the steel slag powder and stirred thoroughly before use. Magnetic separation aims to remove residual elemental iron or ferrous oxide and other magnetic substances from the smelting process. These impurities undergo slow electrochemical corrosion in humid environments, producing rust that expands in volume, creating stress concentration points within the material and disrupting the integrity of the hydration products. The subsequently added slag powder solidifier, also a solid waste from the steel smelting industry, has a specific surface area greater than 400 m² / kg. 2 / kg, mainly composed of glassy structure, has no independent hydraulic properties, but contains a large number of potential active sites. Under the activation conditions of the activator in this scheme, calcium, aluminum, and silicon ions in the glass can dissociate and react with water to generate gelling substances.

[0025] In summary, based on raw material optimization, this invention mixes gravity separation metal tailings powder with polyacrylic acid superabsorbent resin gel blocks for dispersion. Utilizing the coarse particle size and easy drying properties of the gravity separation metal tailings powder, it serves as a framework supporting the drying process of the polyacrylic acid superabsorbent resin gel blocks and acts as an abrasive during the pulverization process, improving the dispersibility of the polyacrylic acid superabsorbent resin powder and thus producing a composite desiccant, avoiding the energy-intensive drying process. After pH adjustment of the flotation metal tailings through pulping, although the specific composition still varies among different minerals, the pH is adjusted to a range favorable for the water absorption of the composite desiccant, while controlling the content of soluble harmful elements. Incorporating this into the treated flotation metal tailings controls moisture and optimizes particle dispersibility. Material B is dry-ball-milled to achieve mechanical activation of the steel slag and ore slag, and combined with diammonium hydrogen phosphate to construct a highly active solidification system. Finally, after mixing 30-50 parts of component A with 30-50 parts of component B and adding water, component B quickly hydrates into a gel, forming a complex cross-linked network. The moisture absorbed by the composite desiccant on the surface of component A can provide hydration conditions for component B. More importantly, it can coordinate with the active sites on the surface of component B, especially the exposed sites of metal ions, and form a strengthening effect through electrostatic interaction.

[0026] On the other hand, the present invention also provides a roadbed stabilizer made from inorganic solid waste, which is prepared by the above-described method for preparing a roadbed stabilizer made from inorganic solid waste.

[0027] Compared with existing technologies, this solution has the following advantages: 1. This invention avoids the energy-intensive drying process in the utilization of metal tailings. For metal tailings obtained by different processes, it integrates them into different stages of the composite desiccant preparation process: gravity separation metal tailings powder particles are coarse and easy to dry. Dispersing, drying and pulverizing them together with polyacrylic acid super absorbent resin is beneficial to improving dispersion effect and drying efficiency; flotation metal tailings fluctuate greatly. pH is adjusted and a low-cost dehydration process is selected to make it compatible with the composite desiccant, which can further control the moisture content and eliminate the drying process of flotation metal tailings, thus achieving the goal of low energy consumption.

[0028] 2. This invention also controls harmful elements to a low level by limiting the technical indicators of metal tailings, steel slag powder, etc. obtained by different processes, preventing harmful elements from damaging the matrix strength and affecting the water absorption effect of polyacrylic acid superabsorbent resin; by mechanically activating and magnetically purifying steel slag and slag powder, its reactivity is significantly improved and unstable factors are eliminated, constructing a highly active alkaline activation and curing system. The control of this invention ensures the stability of the roadbed material performance. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the preparation process of the roadbed stabilizing material in an embodiment of the present invention. Figure 2 Material A obtained in Example 1 of this invention; Figure 3 Material B obtained in Example 1 of this invention; Figure 4 This is a morphological image of the roadbed stabilizing material obtained in Example 1 of the present invention after curing; Figure 5 This is a morphological image of the roadbed stabilizing material prepared in Comparative Example 1 of the present invention after curing. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] The specific solution of this invention is as follows: This invention provides a method for preparing roadbed stabilizer material using inorganic solid waste as raw material, wherein, by mass, it combines... Figure 1 As shown, it includes the following steps: (1) Preparation of gel block: Add 100 parts of acrylic acid to 80-100 parts of water and stir evenly. Then add 0.5-0.8 parts of ammonium persulfate and react at 60-65℃ for 1.5-2.5h. Add 1-3 parts of dicumyl peroxide to the solution after reaction and continue to react at 60-65℃ for 1.5-2.5h to obtain gel block of polyacrylic acid super absorbent resin.

[0032] (2) Preparation of composite desiccant: Add 50-150 mesh gravity separation metal tailings powder to the gel block, stir, crush, dry, and further crush to obtain composite desiccant.

[0033] In this step, the mass ratio of gel block to gravity separation metal tailings powder is 1:30-40; the composite desiccant is dried with hot air at 60℃ and 3L / min nitrogen flow until the moisture content is less than 0.5%, and then the dried material is pulverized to an average particle size of 10-20μm by air jet milling. During the pulverization process, a nitrogen protective atmosphere is maintained and the air flow rate is 340m / s to obtain the composite desiccant. Preferably, the gravity-separated metal tailings powder is one or more of iron tailings, molybdenum tailings, and tungsten tailings; the chloride ion content in the gravity-separated metal tailings powder is ≤0.3%, and the sulfide content is ≤0.5%.

[0034] (3) Preparation of slurry: The flotation metal tailings are treated to make a slurry with a solid mass ratio of 10-15%, and the pH is adjusted to 8-10.

[0035] In this step, the flotation metal tailings are one or more of copper tailings, lead-zinc tailings, or fluorite tailings of 180-220 mesh; the chloride ion content of the flotation metal tailings is ≤0.5%, the sulfide content is ≤1.0%, and the free calcium oxide content is ≤4.0%.

[0036] (4) Preparation of filter cake: Add 0.1-0.3 ppm of PAM to the slurry and dehydrate to a filter cake with a moisture content of 12-18%.

[0037] (5) Preparation of material A: Under stirring conditions of 500-800 rpm, the composite desiccant is added to the filter cake, wherein the mass ratio of filter cake to composite desiccant is 1:1-1.2. After stirring evenly, the mixture is squeezed or rolled to make it dense, and then left to stand for 30-60 minutes to disperse and obtain material A.

[0038] (6) Preparation of material B: Dry ball mill 10-20 parts of steel slag powder, 0.3-1 parts of diammonium hydrogen phosphate and 5-10 parts of slag powder curing agent for 30 minutes to obtain material B.

[0039] In this step, the steel slag powder undergoes magnetic separation to achieve a specific surface area ≥400 m². 2 / kg, the free calcium oxide content of steel slag powder is ≤3.0%; the loose density of material B is 2.0-2.5g / cm³. 3 .

[0040] (4) Preparation of roadbed stabilizer: Mix 30-50 parts of material A with 30-50 parts of material B, add 8-15 parts of water and stir evenly to obtain roadbed stabilizer.

[0041] The present invention will be further illustrated below with specific embodiments: In the examples and comparative examples: The slag powder curing agent used meets the requirements of GB / T18046-2017 "Granulated blast furnace slag powder for use in cement, mortar and concrete"; The gravity separation metal tailings powder, flotation metal tailings and steel slag powder used meet the requirements of GB5085.3—2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification" in terms of heavy metals. The PAM used is anionic polyacrylamide (PAM).

[0042] Example 1 This embodiment provides a method for preparing roadbed stabilizer material using inorganic solid waste as raw material, which includes the following steps by weight: (1) Add 100 parts of acrylic acid to 90 parts of water and stir evenly. Then add 0.6 parts of ammonium persulfate and react at 63°C for 2 hours. Add 2 parts of dicumyl peroxide to the solution after reaction and continue to react at 63°C for 2 hours to obtain a gel block of polyacrylic acid superabsorbent resin.

[0043] (2) Add 100-mesh gravity separation metal tailings powder to the gel block. The mass ratio of the gel block to the gravity separation metal tailings powder is 1:35. Stir and pulverize. Dry with hot air at 60℃ and 3L / min nitrogen flow to a moisture content of 0.35%. Then pulverize the dried material to an average particle size of 15μm by airflow pulverization. Maintain a nitrogen protective atmosphere during pulverization. The airflow rate is 340m / s to obtain a composite desiccant.

[0044] Among them, the gravity separation metal tailings powder is iron tailings; the chloride ion content in the gravity separation metal tailings powder is 0.25%, and the sulfide content is 0.4%.

[0045] (3) Prepare a slurry with a solid mass ratio of 13% (pH 4.8) by flotation metal tailings slurry and adjust the pH to 9.

[0046] The flotation tailings consist of 200-mesh copper tailings; the flotation tailings contain 0.4% chloride ions, 0.8% sulfides, and 3.0% free calcium oxide.

[0047] (4) Add 0.2 ppm of PAM by weight of slurry and dehydrate to filter cake with a moisture content of 15%.

[0048] (5) Under stirring conditions of 650 rpm, the filter cake and composite desiccant were mixed and stirred evenly at a mass ratio of 1:1.1, then extruded and densified, allowed to stand for 45 min, and dispersed to obtain material A. See Figure 2 As shown.

[0049] (6) Dry ball mill 15 parts of steel slag powder, 0.6 parts of diammonium hydrogen phosphate and 7 parts of slag powder curing agent for 30 min to obtain material B.

[0050] Among them, the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area of ​​450 m². 2 / kg, the free calcium oxide content of the steel slag powder is 2.0%; the loose density of material B is 2.3g / cm³. 3 ,See Figure 3 As shown; (7) Mix 40 parts of material A with 40 parts of material B, add 12 parts of water and stir evenly to obtain the roadbed stabilizer.

[0051] The structure of the roadbed stabilizer prepared in this embodiment was tested, and the morphology of the surface after 7 days of curing (100x magnification) is shown in the figure. Figure 4 As shown, from Figure 4 As can be seen from the 100x stereomicroscope, the surface is dense with few microcracks.

[0052] The roadbed stabilizer prepared in this embodiment was tested, and the test results are shown in Table 1.

[0053] Example 2 The only difference between this embodiment and Embodiment 1 is that: (1) Add 100 parts of acrylic acid to 80 parts of water and stir evenly. Then add 0.5 parts of ammonium persulfate and react at 60°C for 2.5 h. Add 1 part of dicumyl peroxide to the solution after reaction and continue to react at 60°C for 2.5 h to obtain a gel block of polyacrylic acid superabsorbent resin.

[0054] (2) Add 50-mesh gravity separation metal tailings powder to the gel block. The mass ratio of gel block to gravity separation metal tailings powder is 1:30. Stir and pulverize. Dry with hot air at 60℃ and 3L / min nitrogen flow to a moisture content of 0.37%. Then pulverize the dried material to an average particle size of 10μm by airflow pulverization. Maintain a nitrogen protective atmosphere during pulverization. The airflow rate is 340m / s. Obtain the composite desiccant.

[0055] Among them, the gravity separation metal tailings powder is molybdenum tailings; the chloride ion content in the gravity separation metal tailings powder is 0.3%, and the sulfide content is 0.3%.

[0056] (3) Prepare a slurry with a solid mass ratio of 10% (pH 6.8) by flotation metal tailings slurry and adjust the pH to 8.

[0057] The flotation tailings are 180-mesh lead-zinc tailings; the flotation tailings contain 0.5% chloride ions, 0.6% sulfides, and 2.5% free calcium oxide.

[0058] (4) Add 0.1 ppm of PAM by weight of slurry and dehydrate to filter cake with a moisture content of 12%.

[0059] (5) Under stirring at 500 rpm, the filter cake and composite desiccant were mixed and stirred evenly at a mass ratio of 1:1, then extruded and compacted, left to stand for 30 minutes, and dispersed to obtain material A.

[0060] (6) Dry ball mill 10 parts of steel slag powder, 0.3 parts of diammonium hydrogen phosphate and 5 parts of slag powder curing agent for 30 min to obtain material B.

[0061] Among them, the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area of ​​400 m². 2 / kg, the free calcium oxide content of the steel slag powder is 1.5%; the loose density of material B is 2.15g / cm³. 3 .

[0062] (7) Mix 30 parts of material A with 30 parts of material B, add 8 parts of water and stir evenly to obtain the roadbed stabilizer.

[0063] The roadbed stabilizer prepared in this embodiment was tested, and the test results are shown in Table 1.

[0064] Example 3 The difference between this embodiment and Example 1 is only that: (1) 100 parts of acrylic acid are added to 100 parts of water and stirred evenly, then 0.8 parts of ammonium persulfate are added and reacted at 65°C for 1.5 hours. 3 parts of dicumyl peroxide are added to the solution after the reaction and the reaction is continued at 65°C for 1.5 hours to obtain a gel block of polyacrylic acid superabsorbent resin.

[0065] (2) Add 150-mesh gravity separation metal tailings powder to the gel block. The mass ratio of the gel block to the gravity separation metal tailings powder is 1:40. Stir and pulverize. Dry with hot air at 60°C and 3L / min nitrogen flow to a moisture content of 0.42%. Then pulverize the dried material to an average particle size of 20μm by airflow pulverization. Maintain a nitrogen protective atmosphere during pulverization. The airflow rate is 340m / s. Obtain the composite desiccant.

[0066] The gravity separation metal tailings powder is tungsten tailings; the chloride ion content in the gravity separation metal tailings powder is 0.1%, and the sulfide content is 0.5%.

[0067] (3) Prepare a slurry with a solid mass ratio of 15% (pH 8.2) by flotation metal tailings slurry and adjust the pH to 10.

[0068] Among them, the flotation metal tailings are fluorite tailings of 220 mesh; the chloride ion content of the flotation metal tailings is 0.2%, the sulfide content is 1.0%, and the free calcium oxide content is 4.0%.

[0069] (4) Add 0.3 ppm of PAM by weight of slurry and dehydrate to filter cake with a moisture content of 18%.

[0070] (5) Under stirring at 800 rpm, the filter cake and composite desiccant were mixed and stirred evenly at a mass ratio of 1:1.2. The mixture was then extruded and compacted, allowed to stand for 60 minutes, and dispersed to obtain material A.

[0071] (6) Dry ball mill 20 parts of steel slag powder, 1 part of diammonium hydrogen phosphate and 10 parts of slag powder curing agent for 30 minutes to obtain material B.

[0072] Among them, the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area of ​​500 m². 2 / kg, the free calcium oxide content of the steel slag powder is 3.0%; the loose density of material B is 2.38 g / cm³. 3 ; (7) Mix 50 parts of material A with 50 parts of material B, add 15 parts of water and stir evenly to obtain the roadbed stabilizer.

[0073] The roadbed stabilizer prepared in this embodiment was tested, and the test results are shown in Table 1.

[0074] Example 4 The only difference between this embodiment and Embodiment 1 is that: (1) Add 100 parts of acrylic acid to 85 parts of water and stir evenly. Then add 0.55 parts of ammonium persulfate and react at 61°C for 2.2 h. Add 1.5 parts of dicumyl peroxide to the solution after reaction and continue to react at 61°C for 2.2 h to obtain a gel block of polyacrylic acid superabsorbent resin.

[0075] (2) Add 80-mesh gravity separation metal tailings powder to the gel block. The mass ratio of gel block to gravity separation metal tailings powder is 1:32. Dry it with hot air at 60℃ and 3L / min nitrogen flow to a moisture content of 0.31%. Then, pulverize the dried material to an average particle size of 12μm by air jet pulverization. Maintain a nitrogen protective atmosphere during the pulverization process. The air flow rate is 340m / s to obtain a composite desiccant.

[0076] The gravity-separated metal tailings powder is a mixture of iron tailings and molybdenum tailings; the chloride ion content in the gravity-separated metal tailings powder is 0.2%, and the sulfide content is 0.35%. (3) Prepare a slurry with a solid mass ratio of 11% (pH 6.5) by flotation metal tailings slurry and adjust the pH to 8.5.

[0077] The flotation metal tailings consist of a mixture of 190-mesh copper tailings and lead-zinc tailings; the flotation metal tailings contain 0.3% chloride ions, 0.7% sulfides, and 2.0% free calcium oxide.

[0078] (4) Add 0.15 ppm of PAM by weight of slurry and dehydrate to filter cake with a moisture content of 14%.

[0079] (5) Under stirring at 600 rpm, the filter cake and composite desiccant were mixed and stirred evenly at a mass ratio of 1:1.05. The mixture was then extruded and compacted, allowed to stand for 35 minutes, and dispersed to obtain material A.

[0080] (6) Dry ball mill 12 parts of steel slag powder, 0.4 parts of diammonium hydrogen phosphate and 6 parts of slag powder curing agent for 30 minutes to obtain material B.

[0081] Among them, the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area of ​​420 m². 2 / kg, the free calcium oxide content of the steel slag powder is 1.0%; the loose density of material B is 2.18 g / cm³. 3 .

[0082] (7) Mix 35 parts of material A with 35 parts of material B, add 9 parts of water and stir evenly to obtain the roadbed stabilizer.

[0083] The roadbed stabilizer prepared in this embodiment was tested, and the test results are shown in Table 1.

[0084] Example 5 The only difference between this embodiment and Embodiment 1 is that: (1) Add 100 parts of acrylic acid to 95 parts of water and stir evenly. Then add 0.75 parts of ammonium persulfate and react at 64°C for 1.8 h. Add 2.5 parts of dicumyl peroxide to the solution after reaction and continue to react at 64°C for 1.8 h to obtain a gel block of polyacrylic acid superabsorbent resin.

[0085] (2) Add 120-mesh gravity separation metal tailings powder to the gel block. The mass ratio of the gel block to the gravity separation metal tailings powder is 1:38. Stir and pulverize. Dry with hot air at 60°C and 3L / min nitrogen flow to a moisture content of 0.3%. Then pulverize the dried material to an average particle size of 18μm by airflow pulverization. Maintain a nitrogen protective atmosphere during pulverization. The airflow rate is 340m / s. Obtain the composite desiccant.

[0086] The gravity-separated metal tailings powder is a mixture of molybdenum tailings and tungsten tailings; the chloride ion content in the gravity-separated metal tailings powder is 0.15%, and the sulfide content is 0.45%.

[0087] (3) Prepare a slurry with a solid mass ratio of 14% (pH 7.3) by flotation metal tailings slurry and adjust the pH to 9.5.

[0088] The flotation metal tailings consist of a mixture of 210-mesh lead-zinc tailings and fluorite tailings; the flotation metal tailings contain 0.45% chloride ions, 0.9% sulfides, and 3.5% free calcium oxide.

[0089] (4) Add 0.25 ppm of PAM by weight of slurry and dehydrate to filter cake with a moisture content of 16%.

[0090] (5) Under stirring at 700 rpm, the filter cake and composite desiccant were mixed and stirred evenly at a mass ratio of 1:1.15. The mixture was then extruded and compacted, allowed to stand for 55 min, and dispersed to obtain material A.

[0091] (6) Dry ball mill 18 parts of steel slag powder, 0.8 parts of diammonium hydrogen phosphate and 9 parts of slag powder curing agent for 30 min to obtain material B.

[0092] Among them, the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area of ​​480 m². 2 / kg, the free calcium oxide content of the steel slag powder is 2.5%; the loose density of material B is 2.34 g / cm³. 3 .

[0093] (7) Mix 45 parts of material A with 45 parts of material B, add 14 parts of water and stir evenly to obtain the roadbed stabilizer.

[0094] The roadbed stabilizer prepared in this embodiment was tested, and the test results are shown in Table 1.

[0095] Comparative Example 1 The only difference between this comparative example and Example 1 is that: Roadbed stabilizer was prepared by directly mixing and stirring gravity separation metal tailings powder, flotation metal tailings, steel slag powder, slag powder solidifier, diammonium hydrogen phosphate and water in the same proportions as in Example 1.

[0096] The structure of the roadbed stabilizer prepared in this embodiment was tested, and the morphology of the surface after 7 days of curing (100x magnification) is shown in the figure. Figure 5 As shown, from Figure 5 As can be seen from the 100x stereomicroscope, there are numerous micro-cracks on the surface.

[0097] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0098] Comparative Example 2 The only difference between this comparative example and Example 1 is that: In step (2), flotation tailings are used instead of gravity separation tailings powder. The time required for hot air drying to a moisture content of 0.35% under nitrogen flow conditions of 60°C and 3L / min is about twice that of Example 1.

[0099] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0100] Comparative Example 3 The only difference between this comparative example and Example 1 is that: In step (2), the mass ratio of gel block to gravity separation metal tailings powder is 1:45.

[0101] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0102] Comparative Example 4 The only difference between this comparative example and Example 1 is that: In step (2), the mass ratio of gel block to gravity separation metal tailings powder is 1:25.

[0103] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0104] Comparative Example 5 The only difference between this comparative example and Example 1 is that: In step (2), the mixture was not dried after being stirred and crushed, and the moisture content was 1.3%.

[0105] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0106] Comparative Example 6 The only difference between this comparative example and Example 1 is that: In step (3), the pH of the slurry was 4.8, and the pH was not adjusted.

[0107] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0108] Comparative Example 7 The only difference between this comparative example and Example 1 is that: PAM was not added in step (4).

[0109] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0110] Comparative Example 8 The only difference between this comparative example and Example 1 is that: In step (4), the moisture content of the filter cake is 20%.

[0111] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0112] Comparative Example 9 The only difference between this comparative example and Example 1 is that: In step (6), the material was not dry-milled for densification, and the loose packing density of material B was 1.54 g / cm³. 3 .

[0113] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0114] Comparative Example 10 The only difference between this comparative example and Example 1 is that: In step (2), the chloride ion content in the gravity separation metal tailings powder is 0.32%, and the sulfide content is 0.54%.

[0115] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0116] Comparative Example 11 The only difference between this comparative example and Example 1 is that: In step (3), the chloride ion content of the flotation metal tailings is 0.53%, the sulfide content is 1.17%, and the free calcium oxide content is 4.3%.

[0117] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0118] Comparative Example 12 The only difference between this comparative example and Example 1 is that: In step (6), the free calcium oxide content of the steel slag powder is 3.3%.

[0119] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0120] Comparative Example 13 The only difference between this comparative example and Example 1 is that: Cancel step (1). In step (2), use commercial polyacrylic acid superabsorbent resin (SDK, Qingdao Shouke New Materials) to mix with gravity separation metal tailings powder.

[0121] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0122] Comparative Example 14 The only difference between this comparative example and Example 1 is that: In step (2), after adding 100-mesh gravity separation metal tailings powder to the gel block, the mass ratio of the gel block to the gravity separation metal tailings powder is 1:35. The mixture is stirred and pulverized, and then dried with hot air at 60°C and 3L / min nitrogen flow to a moisture content of 0.35% to obtain a composite desiccant.

[0123] This step did not involve air jet milling.

[0124] The roadbed stabilizer prepared in this comparative example was tested, and the test results are shown in Table 1.

[0125] The detection methods of the embodiments and comparative examples of the present invention are as follows: 1. Water absorption rate test of composite desiccant: Five 1g portions of composite desiccant were weighed from each group and placed into water. After standing at 25℃ for 60 minutes, the mixture was filtered, drained until no water dripped, and the weight gain was measured. The water absorption specific gravity = (weight after water absorption - 1g) × 100%; 2. Unconfined compressive strength test: All tailings-steel slag co-cured roadbed stabilized materials prepared in all examples and comparative examples were prepared and cured for 7 days according to the Ministry of Transport's "Highway Geotechnical Test Procedure" (JTG-E40) to obtain test samples and test their unconfined compressive strength (MPa). 3. Heavy metal ion leaching concentration test: After the unconfined compressive strength test is completed, take a sample block of the same shape and weight, soak it in water for 7 days, and test whether the leached heavy metals meet the requirements in accordance with the "Groundwater Quality Standard" (GB / T14848-9); 4. Sulfur and chlorine leaching concentration detection: Refer to "HJ557-2010 Solid Waste Leaching Toxicity Leaching Method - Horizontal Oscillation Method"; 5. Water stability test: Refer to the "Immersion test of inorganic binder stabilized materials" in "JTGE40-2007 Highway Geotechnical Test Procedures". After immersion in water for 7 days, measure the compressive strength loss rate (≤15% is excellent). 6. Consistency test: The sinking depth method is used to test the consistency. A standard cone with a mass of 300g and a base diameter of 40mm is freely sunk into the finished products prepared in the examples and comparative examples. The sinking depth is the consistency value.

[0126] The test results are shown in Table 1.

[0127] Table 1 Performance test results of the examples and comparative examples

[0128] In this embodiment and the comparative example, the tailings of the same type all originated from the same mineral source, with little difference in composition, and the leaching of heavy metals met the requirements for heavy metals in GB5085.3.

[0129] Examples 1 to 5, based on raw material control and combined with the differentiated treatment of metal tailings from different processes during preparation, achieved efficient water absorption and uniform dispersion of the composite desiccant, reducing the uncertainties brought about by flotation metal tailings. Finally, combined with the B-material solidification system, high-performance roadbed stabilized material was prepared. The consistency of Examples 1 to 5 was concentrated in the range of 118-132 mm, with narrow fluctuations, meeting the construction and performance requirements of moist solid waste roadbed stabilized material, indicating good batching stability and suitability for quality control during construction.

[0130] Compared to Example 1, Comparative Example 1, due to the direct mixing of materials A and B without pretreatment, resulted in uneven dispersion of solid waste particles, numerous internal voids, and a sharp decrease in strength and water stability due to the acidic nature of the flotation metal tailings. Figure 5 and Figure 4 (Surface of Example 1) It can be seen that, Figure 5There were many obvious microcracks; Comparative Example 2 used flotation metal tailings instead of gravity separation metal tailings powder to prepare a composite desiccant. Because the flotation metal tailings had a fine particle size and large specific surface area, they were prone to agglomeration, resulting in a low consistency of the prepared roadbed stabilizer. This not only hindered the water absorption channels of the polyacrylic acid superabsorbent resin, but also destroyed the water absorption effect due to its acidic characteristics. In addition, the time required for hot air drying to a moisture content of 0.35% under nitrogen flow conditions of 60℃ and 3L / min was about twice that of Example 1, resulting in the loss of energy consumption advantage; Comparative Example 3 had an excessive amount of gravity separation metal tailings powder, which diluted the relative content of polyacrylic acid superabsorbent resin, weakening the humidity regulation ability of the composite desiccant. The resulting roadbed stabilizer had a low consistency and could not effectively alleviate roadbed shrinkage; Comparative Example 4 had a low consistency of gravity separation metal tailings powder. Insufficient tailings powder caused the superabsorbent polyacrylic acid resin to swell excessively due to a lack of rigid particle support, crowding out the internal pores of the roadbed. This resulted in a roadbed stabilizer with high consistency, affecting structural density. In Comparative Example 5, the composite desiccant was not dried, and residual moisture prematurely occupied the water absorption sites of the superabsorbent polyacrylic acid resin and the capillaries of the tailings, causing the composite desiccant to malfunction and interfering with the hydration reaction of material B. In Comparative Example 6, the pH of the flotation metal tailings was not adjusted, and the acidic environment prevented the precipitation of metal ions on the tailings surface. This led to easy leaching of sulfur and chlorine elements and weakened the interfacial bonding strength between the flotation metal tailings and the composite desiccant. In Comparative Example 7, the absence of PAM prevented the formation of flocs from the fine particles of the flotation metal tailings, resulting in poor dispersibility and difficulty in encapsulating free harmful ions, thus affecting the overall structure. Overall stability of the roadbed; Comparative Example 8: Due to the excessive moisture content of the filter cake from the flotation metal tailings, even after the composite desiccant absorbed the excess moisture, material A remained overly wet, hindering the uniform hydration of material B and the compaction of the roadbed, resulting in low consistency; Comparative Example 9: Because material B was not dry-milled for densification, the steel slag and ore particles had low surface energy and few lattice defects, their activity could not be effectively activated, the solidification system had insufficient strength and poor water stability, and the loose density was low, indicating insufficient contact between particles; Comparative Example 10: Due to the excessive sulfur and chlorine content in the gravity separation metal tailings powder, harmful ions would slowly corrode the polyacrylic acid superabsorbent resin molecular chains and block the matrix pores, reducing the water absorption efficiency of the composite desiccant and the impermeability of the roadbed; Comparative Example 11: Due to the excessive sulfur and chlorine content and free calcium oxide content in the flotation metal tailings... This not only exacerbates the risk of harmful ion leaching, but also causes microcracks in the roadbed due to the volume expansion caused by the later hydration of free calcium oxide. In Comparative Example 12, the free calcium oxide content of steel slag exceeded the standard, and the volume increased during the later hydration to form calcium hydroxide, which destroyed the overall structure of the solidified body and led to a decrease in strength and water stability. In Comparative Example 13, the use of commercial polyacrylic acid superabsorbent resin and gravity separation metal tailings powder for physical mixing did not form a synergistic effect of in-situ polymerization, and the resin was prone to agglomeration, making it impossible to achieve uniform dispersion and efficient water absorption and release. In Comparative Example 14, the composite desiccant was not treated with airflow pulverization, and the uneven particle size caused the composite desiccant to be dispersed unbalanced in the roadbed, resulting in inconsistent water absorption and release behavior, and local shrinkage or bleeding, which affected the stability of the roadbed performance.

Claims

1. A method for preparing roadbed stabilizer material using inorganic solid waste as raw material, characterized in that, By weight, the following steps are included: (1) Preparation of gel block: Add 100 parts of acrylic acid to 80-100 parts of water, stir evenly, add 0.5-0.8 parts of initiator, react at 60-65℃ for 1.5-2.5h, add 1-3 parts of crosslinking agent, and continue to react at 60-65℃ for 1.5-2.5h to obtain gel block of polyacrylic acid super absorbent resin; (2) Preparation of composite desiccant: 50-150 mesh gravity separation metal tailings powder is added to the gel block and stirred, crushed, dried and further crushed to obtain composite desiccant; wherein, the mass ratio of the gel block and the gravity separation metal tailings powder is 1:30-40, the moisture content of the composite desiccant is less than 0.5% and the average particle size is 10-20μm; (3) Preparation of slurry: The flotation metal tailings are subjected to pulping treatment to obtain slurry; the solid mass ratio of the slurry is 10-15%, and the pH value is 8-10; (4) Preparation of filter cake: Add 0.1-0.3 ppm of PAM by weight of the slurry to the slurry for dehydration treatment to obtain a filter cake with a moisture content of 12-18%; (5) Preparation of material A: Under stirring conditions, filter cake and composite desiccant are mixed at a mass ratio of 1:1-1.2, followed by densification, settling and dispersion treatment to obtain material A; (6) Preparation of material B: 10-20 parts of steel slag powder, 0.3-1 parts of diammonium hydrogen phosphate and 5-10 parts of slag powder curing agent are dry ball milled and densified to obtain material B; (7) Preparation of roadbed stabilizer: Mix 30-50 parts of material A and 30-50 parts of material B, add 8-15 parts of water, stir evenly, and obtain roadbed stabilizer.

2. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (1), the initiator is ammonium persulfate and the crosslinking agent is dicumyl peroxide.

3. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (2), the gravity separation metal tailings powder is one or more of iron tailings, molybdenum tailings, and tungsten tailings.

4. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 3, characterized in that, The chloride ion content of the gravity separation metal tailings powder is ≤0.3%, and the sulfide content is ≤0.5%.

5. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (2), the further pulverization process is as follows: the dried material is pulverized to an average particle size of 10-20 μm by air jet pulverization, and a nitrogen protective atmosphere is maintained during the pulverization process.

6. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (3), the flotation metal tailings are one or more of copper tailings, lead-zinc tailings or fluorite tailings of 180-220 mesh.

7. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 6, characterized in that, The flotation tailings have a chloride ion content ≤0.5%, a sulfide content ≤1.0%, and a free calcium oxide content ≤4.0%.

8. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (5), the stirring conditions are 500-800 rpm; the densification process is extrusion or rolling; and the settling time is 30-60 min.

9. The method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in claim 1, characterized in that, In step (6), the steel slag powder undergoes magnetic separation treatment, resulting in a specific surface area ≥ 400 m². 2 / kg, wherein the free calcium oxide content of the steel slag powder is ≤3.0%.

10. A roadbed stabilizing material using inorganic solid waste as raw material, characterized in that, It is prepared by the method for preparing roadbed stabilizer material using inorganic solid waste as raw material as described in any one of claims 1-9.

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