Multi-element solid waste curing agent as well as preparation method and application thereof

Abstract

The invention belongs to the field of soil stabilizers, and particularly relates to a multi-element solid waste-based soil stabilizer as well as a preparation method and application thereof. The method comprises the following steps: respectively blending and ball-milling steel slag and red mud with a grinding aid to obtain ball-milled red mud and ball-milled steel slag powder; the rice hulls are subjected to phosphoric acid dipping and firing, and rice hull ash is obtained. And mixing carbide slag as an alkali activator and rice hull ash as a binder with the ball-milled red mud and the ball-milled steel slag powder to obtain the multi-element solid waste-based soil stabilizer. The invention provides an environment-friendly, efficient and low-cost resource utilization way for broadening the four solid wastes such as the steel slag, the red mud, the carbide slag and the rice hull ash, high-valued utilization of the four solid wastes is realized, the comprehensive utilization level of solid wastes is improved, energy conservation and carbon reduction of the comprehensive utilization industry of resources are promoted, and the method has wide and profound practical significance.

Description

Technical Field

[0001] The invention belongs to the field of soil solidifying agents, and in particular relates to a multi-component solid waste solidifying agent and a preparation method and application thereof. Background Art

[0002] In road construction projects, soil solidification technology is one of the most common methods for roadbed reinforcement. Soil solidification technology uses a physical and chemical reaction between a curing agent and soil particles to bond loose soil particles into a stable whole, improve soil quality, and enhance adhesion, thereby achieving the purpose of roadbed reinforcement. Cement is the most traditional soil solidification material. However, years of engineering practice have shown that cement-solidified soil often has the problem of insufficient early strength, which affects the quality and construction period of the project. In addition, cement production often consumes a large amount of clay resources and energy, and will emit more greenhouse gases and pollutants, which will bring a serious burden to the environment. Therefore, it is very necessary to develop a high-performance and environmentally friendly curing agent to replace cement.

[0003] Red mud is a byproduct of the production of alumina using alkali-impregnated bauxite. Its main components are iron oxide, aluminum oxide, silicon oxide and calcium oxide. In 2023, my country's red mud production was 107 million tons, while its utilization was only 10 million tons, with a utilization rate of 9.8%. A large amount of red mud has not been effectively utilized, occupying a large amount of land resources, posing a serious threat to the environment, and the annual maintenance costs are in the hundreds of millions, which seriously restricts the sustainable development of my country's alumina industry. Therefore, large-scale resource utilization of red mud is urgent.

[0004] Steel slag is an industrial waste produced by the steelmaking industry, and its emission is 15% to 20% of crude steel. Large amounts of steel slag will cause waste of resources, occupy land resources and cause environmental pollution. With the development of my country's steel industry, my country's steel slag production has continued to rise, but its consumption capacity is lower than the amount of steel slag emissions, resulting in the gradual increase in steel slag reserves. Therefore, how to quickly and effectively use steel slag on a large scale has become a research hotspot.

[0005] Studies have shown that using red mud and steel slag to prepare curing agents for use in the field of road construction materials can maximize the resource utilization of red mud and steel slag. However, when using red mud and steel slag to prepare curing agents, a large amount of alkali activator needs to be added, which increases the resource cost of red mud.

[0006] Silicon phosphate is a new type of waterproof adhesive curing agent. The industrial production of silicon phosphate is mainly obtained by reacting diatomaceous earth, a non-renewable mineral, with phosphoric acid. On the one hand, diatomaceous earth is expensive and non-renewable, and is limited by resources; on the other hand, the process and equipment are complex and energy consumption is high, resulting in silicon phosphate being too expensive to be used in large quantities. Some people use rice husks directly burned into rice husk ash (grey powder containing more than 90% silicon dioxide) and directly reacted with phosphoric acid to produce silicon phosphate. However, its preparation temperature is too high (≥750℃), which causes the active amorphous SiO2 in the rice husk to transform into an inactive fixed state, reducing the activity of the rice husk ash. Summary of the invention

[0007] The purpose of the present invention is to provide a multi-solid waste-based soil solidifying agent and a preparation method and application thereof.

[0008] In order to achieve the above objectives, the first aspect of the present invention is to provide a multi-solid waste-based soil solidifier, which is composed of 25% to 35% ball-milled red mud, 35% to 45% ball-milled steel slag, 15% to 25% carbide slag and 5% to 15% phosphoric acid-modified rice husk ash; the percentages are mass fractions;

[0009] The preparation process of the phosphoric acid modified rice husk ash is as follows: taking rice husk powder, mixing it with a phosphoric acid solution with a mass concentration of 80-90% according to a molar ratio of Si:P=1:2-1:5, immersing it for 0.5-1.5h, and calcining it at 400-700℃ for 2-3h to obtain phosphoric acid modified rice husk ash.

[0010] The ball-milled red mud and the ball-milled steel slag are obtained by activating the red mud and the steel slag through ball milling, respectively, and anhydrous sodium carbonate is added during the ball milling activation.

[0011] In a preferred embodiment, the multi-solid waste-based soil solidifier consists of 30% ball-milled red mud, 40% ball-milled steel slag, 20% carbide slag and 10% phosphoric acid-modified rice husk ash.

[0012] The second aspect of the present invention is to disclose a method for preparing a multi-solid waste-based soil solidifying agent, comprising the following steps:

[0013] (1) taking steel slag or red mud, mixing it with a grinding aid, and then ball milling it to obtain ball-milled red mud and ball-milled steel slag respectively;

[0014] (2) taking rice husk powder, mixing it with a phosphoric acid solution with a mass concentration of 80-90% according to a molar ratio of Si:P=1:2-1:5, immersing it for 0.5-1.5 hours, and calcining it at 400-700°C for 2-3 hours to obtain phosphoric acid-modified rice husk ash;

[0015] (3) Ball-milled red mud, ball-milled steel slag, carbide slag powder and phosphoric acid-modified rice husk ash are mixed thoroughly to obtain a multi-solid waste-based soil stabilizer.

[0016] In a preferred embodiment, the grinding aid is 1-3wt.% anhydrous sodium carbonate, 1-3wt.% refers to the mass ratio of anhydrous sodium carbonate to steel slag or red mud; the ball mill speed is 500-700r / min; and the ball mill time is 5-15min.

[0017] In step (3), the ball-milled red mud, ball-milled steel slag, carbide slag powder and phosphoric acid-modified rice husk ash are sieved before mixing, and the sieve aperture is 100-200 mesh, preferably 200 mesh.

[0018] In a preferred embodiment, the concentration of the phosphoric acid solution in step (2) is 85.11wt.%; according to the molar ratio of Si:P=1:2.5-3.5, the rice husk and the phosphoric acid solution are weighed and fully mixed; the calcination temperature is 600°C; and the calcination time is 2.5h. The high concentration of phosphoric acid is used to make the rice husk fully contact with the phosphoric acid and ensure that the phosphoric acid is excessive, so that the phosphorus and phosphate radicals fully modify the rice husk ash. When the Si:P molar ratio is too large, the phosphoric acid will not modify the rice husk ash sufficiently, affecting the adhesion and water resistance, and the unit structures of Si-O-Al-OP and Si-OP formed are less, and the synergistic hydration and mechanical properties are reduced; when the Si:P molar ratio is too small, the relative contents of active silicon and rice husk ash are reduced, reducing the nucleation sites, seed effect and hydration, and weakening the formation of C-(A)-SH) gel.

[0019] In a preferred embodiment, the multi-solid waste-based soil stabilizer consists of 30% ball-milled red mud, 40% ball-milled steel slag, 20% carbide slag and 10% phosphoric acid-modified rice husk ash.

[0020] The third aspect of the present invention is to provide the application of the aforementioned multi-solid waste-based soil solidifying agent as a road building material, specifically, in highway and railway engineering.

[0021] The fourth aspect of the present invention is to disclose the use of the aforementioned multi-solid waste-based soil solidifier in soil solidification.

[0022] The present invention introduces carbide slag and rice husk ash impregnated with phosphoric acid as alkaline activators and binders. Carbide slag is the waste residue with calcium hydroxide as the main component after acetylene gas is obtained by hydrolyzing calcium carbide. Its main components are CaO and Ca(OH)2, and its content is greater than 90%, which has the potential to be used as an alkaline activator. In the present invention, rice husks are impregnated with high-concentration phosphoric acid and activated by burning at a slightly lower temperature. On the one hand, part of the active silicon dioxide is converted into silicon phosphate, which acts as a binder to enhance the adhesion and water resistance of the solidified body. The phosphoric acid-modified rice husk ash contributes active silicon, which is adsorbed onto red mud and steel slag particles as nucleation sites, accelerates hydration through surface protonation, electrostatic attraction and seed effect, and reacts with the Ca released by the carbide slag. 2+ The reaction forms hydrated calcium silicate (aluminum) gel (C-(A)-SH) gel.

[0023] The benefit of the present invention lies in that the curing agent of the present invention is a full solid waste curing agent, and the complementary advantages and synergistic effects of the four materials are utilized to prepare a soil curing agent with excellent performance, and the main raw materials are red mud, steel slag, carbide slag and phosphoric acid modified rice husk ash. The red mud and steel slag are activated by mechanical grinding, and anhydrous sodium carbonate is added as a grinding aid to carry out mixed grinding, thereby destroying the crystal form of the red mud and steel slag, generating lattice distortion and lattice defects, reducing the apparent activation energy, and promoting the activation of Si and Al. The rice husk ash is phosphate-modified and calcined to prepare modified rice husk ash rich in silicon phosphate. When phosphoric acid-modified rice husk ash is burned, a series of silicon phosphate products will be formed. Red mud is rich in Al element, and it is mainly composed of silicate and aluminate tetrahedrons with low polymerization degree. When red mud is exposed to the strong alkaline environment produced by carbide slag and steel slag, the aluminosilicate tetrahedron disintegrates to generate active silicate and aluminate anions. The silicates and aluminates in steel slag are highly active and can react quickly to increase the formation of early hydration products to compensate for the problem of insufficient early strength. At the same time, the alkaline components of carbide slag optimize the pH value of the system and enhance the environmental stability of the material. Phosphoric acid-modified rice husk ash contributes active silicon, which is adsorbed onto red mud and steel slag particles as nucleation sites, accelerates hydration through the seed effect, and reacts with the Ca released by carbide slag. 2+ The reaction forms C-(A)-SH gel. It can provide sufficient H + , replacing the Na in the traditional binder (water glass) + , released into the curing system, reducing the water absorption of the sample. + The release rate is relatively slow, lower than that of traditional curing agents such as aluminum phosphate, so it is easier to form uniform chain polymers in the curing system, and can make the sample present a single uniform structure, reduce the water permeability of the cured body, and improve its water stability and compressive strength. In the early stage, through the nanofilling effect, harmful gaps are filled to promote the release of water and Ca 2+ It enters the pores of the solidified body from the outside to form C-(A)-SH gel, which improves the density and bonding strength of the solidified body. At the same time, [PO4] in the phosphoric acid-modified rice husk ash partially replaces [SiO4] to form unit structures of Si-O-Al-OP and Si-OP. These unit structures and C-(A)-SH gel continuously polymerize to form a three-dimensional spatial network, strengthen the composite structure, synergize the hydration, and enhance the hydration and mechanical properties of the solidified body.

[0024] The present invention uses red mud and steel slag as the main raw materials, adopts a mechanical activation method, and mixes and grinds with anhydrous sodium carbonate to enhance its activity; adds strongly alkaline calcium carbide slag as an alkali activator, and phosphoric acid-modified rice husk ash as a silicon source and a binder, and mixes them in a certain proportion to obtain a multi-solid waste soil solidifier with excellent performance to replace traditional cement, and is used for roadbed solidification and stabilization treatment, reducing greenhouse gas emissions and alleviating the greenhouse effect. At the same time, compared with cement, traditional solid waste is cheaper and easier to obtain, and has obvious price advantages. The present invention uses a variety of large amounts of industrial solid waste and agricultural waste, which not only broadens the resource utilization of four solid wastes such as steel slag, red mud, calcium carbide slag and rice husk ash, realizes the high-value utilization of the four solid wastes, and improves the comprehensive utilization level of solid wastes, promotes energy conservation and carbon reduction in the comprehensive utilization of resources industry, and has broad and far-reaching practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 to Figure 6 They are the effects of the interaction between the raw materials on the UCS of the solidified body;

[0026] Figure 1 The contour map of the effect of the interaction between red mud and steel slag on the UCS of the solidified body;

[0027] Figure 2 The contour map of the effect of the interaction between red mud and carbide slag on the UCS of the solidified body;

[0028] Figure 3 The contour map of the effect of the interaction between red mud and phosphoric acid-modified rice husk ash on the UCS of the solidified body;

[0029] Figure 4 The contour map of the effect of the interaction between steel slag and carbide slag on the UCS of the solidified body;

[0030] Figure 5 The contour map of the effect of the interaction between steel slag and phosphoric acid-modified rice husk ash on the UCS of the solidified body;

[0031] Figure 6 The contour map of the effect of the interaction between carbide slag and phosphoric acid-modified rice husk ash on the UCS of the solidified body;

[0032] Figure 7 Schematic diagram of mass loss rate of the solidified bodies of Examples 2 and 3 and Comparative Example 1 after immersion in water for 15 days. DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] In the following examples, if no specific techniques or conditions are specified, all are conventional methods or are carried out according to the techniques or conditions described in the literature of the field, or according to the product instructions. The reagents and instruments used, if the manufacturers are not specified, are all conventional products that can be purchased through regular channels. Unless otherwise specified, the materials, reagents, etc. used in the following examples, if not otherwise specified, can be obtained from commercial channels.

[0035] In the embodiment of the present invention, the curing agent dosage is 10wt%, and the curing agent dosage refers to the mass percentage of the curing agent in the mixture formed by air-dried soil and multi-solid waste-based soil curing agent. The physical and chemical properties and particle size distribution of the experimental soil are shown in Tables 1 and 2. Before use, the soil was air-dried under natural conditions. In the present invention, the solidified soil specimens are formed by static pressure molding, the bearing pressure is 30kN, and the load time is 2min. The test method of the 3d unconfined compressive strength of the solidified soil specimens refers to the test method in the "Test Code for Stabilized Materials of Inorganic Binders for Highway Engineering" (JTGE51-2009). After the solidified soil specimens are formed, they are cured in a spray curing room at 25°C for 3d, and then the 3d unconfined compressive strength is detected by a universal press; after detecting the 3d unconfined compressive strength, the unconfined compressive strength is measured after immersion in water for 24h and the strength loss rate of immersion in water for 24h is calculated; after detecting the 3d unconfined compressive strength, the solidified body mass loss rate is measured after immersion in water for 15d.

[0036] The physical and chemical properties and particle size of the soil to which the curing agent and deionized water were added are shown in Tables 1 and 2, respectively, and the content of SiO2 in the rice husk ash is 88.61 wt%, as shown in Table 3. The preparation process of the rice husk ash in Table 3 is as follows: 5-10 g of rice husk powder is taken, put into a muffle furnace, and calcined at a temperature of 600°C for 2.5 h to obtain rice husk ash.

[0037] Table 1 Physical and chemical properties of soil

[0038]

[0039] Table 2 Soil particle size distribution

[0040]

[0041] Table 3 Chemical composition of rice husk ash

[0042] Components <![CDATA[SiO2]]> <![CDATA[K2O]]> <![CDATA[Fe2O3]]> CaO <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MnO MgO <![CDATA[Na2O]]> Content / wt.% 88.61 4.07 1.17 1.06 0.721 0.619 0.448 0.405 0.108

[0043] Example 1

[0044] This embodiment provides a multi-solid waste-based soil solidifying agent, and the preparation method thereof is as follows:

[0045] (1) Red mud, steel slag, carbide slag and rice husk are dried in an oven at 105°C to constant weight and placed in a desiccator for later use.

[0046] (2) Take the dried steel slag or red mud in step (1), mix them with 2 wt.% of anhydrous sodium carbonate, and use a planetary ball mill to ball mill them at a speed of 600 r / min for 10 min. After the ball milling, pass through a 200 mesh sieve to obtain ball-milled red mud powder and ball-milled steel slag powder, respectively, and place them in an oven to dry for later use.

[0047] (3) Grind the carbide slag in step (1) with a corundum mortar and pass it through a 200-mesh sieve to obtain carbide slag powder, which is placed in a desiccator for later use.

[0048] (4) Take the rice husk dried in step (1), crush it with a high-speed crusher and pass it through a 200-mesh sieve to obtain rice husk powder, and place it in a dryer for later use.

[0049] (5) Take the rice husk powder in step (4), fully mix it with a phosphoric acid solution with a mass concentration of 85.11% according to a molar ratio of Si:P=1:3.5, soak it for 1 hour, send it into a muffle furnace, and burn it at a temperature of 600°C for 2.5 hours to obtain phosphoric acid-modified rice husk ash, pass it through a 200-mesh sieve, and place it in a dryer for use. Si:P=1:3.5 is determined as follows: when obtaining Table 3, a certain amount of rice husk powder is obtained to obtain a certain amount of rice husk ash, and the content of SiO2 in the rice husk ash is 88.61wt%. After conversion, the amount of silicon contained in a certain amount of rice husk powder is obtained; according to the molar ratio of Si:P=1:3.5, the rice husk powder is mixed with the phosphoric acid solution.

[0050] (6) According to Table 4, take the ball-milled red mud and ball-milled steel slag in step (2), the carbide slag powder in step (3), and the phosphoric acid-modified rice husk ash in step (5), and mix them with air-dried soil, wherein the curing agent is added in an amount of 10wt%, and then add 10.3wt.% of deionized water (air-dried soil, curing agent and deionized water form a mixture, and 10.3wt.% refers to the mass percentage of deionized water in the mixture), stir well, transfer to a cylindrical mold with a diameter of 50mm and a height of 50mm, and compact and shape. Cured according to the experimental method, the 3d unconfined compressive strength UCS of the samples was tested respectively.

[0051] (7) The mix ratio design of the curing agent raw materials and the results are shown in Table 4 below.

[0052] Table 4 Raw material mix design and results

[0053]

[0054] Parts in Table 4 are parts by weight.

[0055] According to the principle of response surface analysis, the curvature of the response surface is relatively high, indicating that the interaction between the raw materials is very significant, which means that a synergistic effect is produced between the raw materials. When the solidification system is a ternary system of steel slag-carbide slag-rice husk ash, the UCS of the solidified body first increases and then decreases with the increase of red mud content. Due to the increase in red mud content, the content of aluminosilicate in the system increases, and it disintegrates in a strong alkaline environment to generate active silicate and aluminate anions, which combine with the active Si in rice husk ash to form nucleation sites on the surface of the material and attract free Ca 2+ , generating C-(A)-SH) gel. When its content is too high, other metal oxides such as Fe2O3 and other substances have too high content, which hinders the polymerization reaction of the monomer and the formation of the hydrated phase (C-(A)-SH)). Steel slag and carbide slag show the same trend. This is because red mud and steel slag undergo hydration reaction in a strong alkaline environment to generate a hydrated phase. However, this process will not convert OH - and Ca 2+ Excessive steel slag and carbide slag will produce excessive OH - and Ca 2+ , causing serious efflorescence and carbonization reaction, thus reducing the mechanical properties of the solidified body. Regarding phosphoric acid-modified rice husk ash, when its content is too high, a large amount of Si-OP structure will be generated at the end, hindering the formation of hydrated phase (C-(A)-SH)). Figure 1 to Figure 6 The contour map clearly shows that the unconfined compressive strength of the solidified body has significant extreme values, and the raw material ratio is approximately red mud: steel slag: carbide slag: modified rice husk ash = 6:8:4:2. Therefore, the preferred raw material ratio of the curing agent can be obtained as red mud: steel slag: carbide slag: phosphoric acid modified rice husk ash = 30%:40%:20%:10%.

[0056] Example 2

[0057] (1) Red mud, steel slag, carbide slag and rice husk are dried in an oven at 105°C to constant weight and placed in a desiccator for later use.

[0058] (2) Take the dried steel slag or red mud in step (1), mix them with 2 wt.% of anhydrous sodium carbonate, and use a planetary ball mill to mill them at a speed of 600 r / min for 10 min. After the ball milling, pass through a 200 mesh sieve to obtain ball-milled red mud and steel slag powder, which are placed in an oven for drying.

[0059] (3) Grind the carbide slag in step (1) with a corundum mortar and pass it through a 200-mesh sieve to obtain carbide slag powder, which is placed in a desiccator for later use.

[0060] (4) Take the rice husk dried in step (1), crush it with a high-speed crusher and pass it through a 200-mesh sieve to obtain rice husk powder, and place it in a dryer for later use.

[0061] (5) Take the rice husk powder in step (4), fully mix it with a phosphoric acid solution with a mass concentration of 85.11% according to a molar ratio of Si:P=1:3.5, soak it for 1 hour, send it into a muffle furnace, and calcine it at a temperature of 600°C for 2.5 hours to obtain rice husk ash, pass it through a 200-mesh sieve, and place it in a dryer for later use.

[0062] (6) According to Example 1, the preferred proportion of raw materials is obtained, and the ball-milled red mud (30%) in step (2), the ball-milled steel slag (40%), the carbide slag powder (20%) in step (3), and the phosphoric acid-modified rice husk ash (10%) in step (5) are taken, and after thorough mixing, a multi-solid waste-based soil solidifier is obtained.

[0063] (7) Take the curing agent in step (6), mix it with the air-dried soil at a dosage of 10%wt, add 10.3wt.% deionized water, stir it thoroughly, transfer it to a cylindrical mold with a diameter of 50mm and a height of 50mm, and compact it into shape. Curing is carried out according to the experimental method, and the unconfined compressive strength of the samples is tested respectively. The unconfined compressive strength after 24h immersion in water and the mass loss rate after 15 days of immersion in water. The test results are shown in Tables 5-6 and Figure 7 It can be seen that Examples 2 to 3 have higher unconfined compressive strength and lower strength loss rate and mass loss rate than Comparative Example 1, which indicates that the soil solidifier provided by the present invention can significantly improve the strength and water resistance of the soil.

[0064] Example 3

[0065] The same method as in Example 2 was used, except that the molar ratio Si:P was 1:2.5 when phosphoric acid was modified into rice husk ash. The test results are shown in Tables 5-6 and Figure 7 .

[0066] Comparative Example 1

[0067] The same method as in Example 2 was used, except that the rice husk powder was only calcined at 600°C for 2.5 h and was not modified with phosphoric acid. The test results are shown in Tables 5-6 and Figure 7 .

[0068] Comparative Example 2

[0069] (1) Red mud, steel slag, carbide slag and rice husk are dried in an oven at 105°C to constant weight and placed in a desiccator for later use.

[0070] (2) Take the dried steel slag or red mud in step (1), mix them with 2 wt.% of anhydrous sodium carbonate, and use a planetary ball mill to ball mill them at a speed of 600 r / min for 10 min. After the ball milling, pass through a 200 mesh sieve to obtain ball-milled red mud and steel slag powder, which are placed in a desiccator for later use.

[0071] (3) Grind the carbide slag in step (1) with a corundum mortar and pass it through a 200-mesh sieve to obtain carbide slag powder, which is placed in a desiccator for later use.

[0072] (4) Take the rice husk dried in step (1), crush it with a high-speed crusher and pass it through a 200-mesh sieve to obtain rice husk powder, and place it in a dryer for later use.

[0073] (5) Take the rice husk powder in step (4), put it into a muffle furnace, and burn it at a temperature of 600° C. for 2.5 hours to obtain rice husk ash, pass it through a 200-mesh sieve, and place it in a dryer for later use.

[0074] (6) Take the ball-milled red mud (30 wt.%) in step (2), the ball-milled steel slag (40 wt.%), the carbide slag powder (20 wt.%) in step (3), and the rice husk ash (10 wt.%) in step (5), and mix them thoroughly to obtain a multi-solid waste solidifying agent.

[0075] (7) According to the molar ratio of Si:P=1:3.5, phosphoric acid solution (mass concentration of 85.11wt.%) and SiO2 solution (mass concentration of 40wt.%) were weighed respectively, mixed thoroughly, and burned in a muffle furnace at 600°C for 3h to obtain white solid silicon phosphate. The solid was sieved through a 200-mesh sieve and placed in a desiccator for later use.

[0076] (8) Take the curing agent in step (6), mix it with the air-dried soil in an amount of 10wt%, then add 1wt.% of the silicon phosphate in step (7) (the air-dried soil and the curing agent form a mixture, 1wt.% refers to the mass percentage of silicon phosphate and the mixture), add 10.3wt.% of deionized water, stir thoroughly, transfer to a cylindrical mold with a diameter of 50mm and a height of 50mm, and compact it into shape. Curing is carried out according to the experimental method of Example 1, and the unconfined compressive strength of the samples and the unconfined compressive strength after 24h immersion in water are tested respectively. The test results are shown in Table 5. As can be seen from Table 5, Example 2 has higher unconfined compressive strength and lower strength loss rate than Comparative Example 2, indicating that phosphoric acid-modified rice husk ash can significantly improve the strength and water resistance of the soil compared with Comparative Example 2 in which rice husk ash and silicon phosphate are added separately.

[0077] Comparative Example 3

[0078] The same method as in Example 2 was adopted, except that the steel slag and red mud were not ball-milled, but only dried, crushed, ground and screened. The 3d unconfined compressive strength of the solidified test block was 4.73 MPa.

[0079] Table 5 Unconfined compressive strength, unconfined compressive strength after 24h immersion and strength loss rate

[0080]

[0081] Table 6 Mass loss rate after 15 days of immersion in water

[0082]

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-solid waste-based soil solidifier, characterized in that: The multi-solid waste-based soil solidifier is composed of 25% to 35% ball-milled red mud, 35% to 45% ball-milled steel slag, 15% to 25% carbide slag and 5% to 15% phosphoric acid-modified rice husk ash; the percentages are mass fractions; The preparation process of the phosphoric acid-modified rice husk ash is as follows: rice husk powder is taken, mixed with a phosphoric acid solution with a mass concentration of 80-90% according to a molar ratio of Si:P=1:2-1:5, immersed for 0.5-1.5 hours, and calcined at 400-700°C for 2-3 hours to obtain phosphoric acid-modified rice husk ash.

2. A multi-solid waste-based soil solidifying agent according to claim 1, characterized in that: The ball-milled red mud and the ball-milled steel slag are obtained by respectively activating the red mud and the steel slag through ball milling, and anhydrous sodium carbonate is added during the ball milling activation.

3. The multi-solid waste-based soil solidifying agent according to claim 1, characterized in that: The multi-solid waste-based soil solidifier is composed of 30% ball-milled red mud, 40% ball-milled steel slag, 20% carbide slag and 10% phosphoric acid-modified rice husk ash.

4. The method for preparing a multi-solid waste-based soil solidifying agent according to claim 1, characterized in that: (1) steel slag or red mud is mixed with a grinding aid and then ball-milled to obtain ball-milled red mud and ball-milled steel slag respectively; (2) taking rice husk powder, mixing it with a phosphoric acid solution with a mass concentration of 80-90% in a molar ratio of Si:P=1:2-1:5, impregnating it for 0.5-1.5 hours, and calcining it at 400-700°C for 2-3 hours to obtain phosphoric acid-modified rice husk ash; (3) Ball-milled red mud, ball-milled steel slag, carbide slag powder and phosphoric acid-modified rice husk ash are mixed thoroughly to obtain a multi-solid waste-based soil stabilizer.

5. The method for preparing a multi-solid waste-based soil solidifying agent according to claim 4, characterized in that: The grinding aid is 1-3wt.% anhydrous sodium carbonate; the ball milling speed is 500-700r / min; and the ball milling time is 5-15min.

6. The method for preparing a multi-solid waste-based soil solidifying agent according to claim 4, characterized in that: In step (3), the ball-milled red mud, ball-milled steel slag, carbide slag powder and phosphoric acid-modified rice husk ash are sieved before mixing, and the sieve aperture is 100 mesh to 200 mesh.

7. The method for preparing a multi-solid waste-based soil solidifying agent according to claim 4, characterized in that: The concentration of the phosphoric acid solution in step (2) is 85.11 wt.%; according to the molar ratio of Si:P=1:2.5-3.5, rice husks and phosphoric acid solution are weighed and fully mixed; the calcination temperature is 600°C; and the calcination time is 2.5 hours.

8. The method for preparing a multi-solid waste-based soil solidifying agent according to claim 4, characterized in that: The multi-solid waste-based soil stabilizer is composed of 30% ball-milled red mud, 40% ball-milled steel slag, 20% carbide slag and 10% phosphoric acid-modified rice husk ash.

9. Use of the multi-solid waste-based soil solidifier according to any one of claims 1 to 3 as a road building material.

10. Use of the multi-solid waste-based soil solidifier according to any one of claims 1 to 3 in soil solidification.

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