Alkali-activated lithium slag-based foam light mixed soil and preparation method thereof

Abstract

The invention discloses alkali-activated lithium slag-based foam light-weight mixed soil prepared from waste mud and a preparation method of the alkali-activated lithium slag-based foam light-weight mixed soil, and belongs to the technical field of foam light-weight soil. The concrete is prepared from the following raw materials in parts by weight: 9.6-21.6 parts of lithium slag, 7.2-12 parts of waste mud, 0.35-0.75 part of bubble groups, 0-0.6 part of a waterproof agent and 1-2.2 parts of an alkali activator, the alkali activator is a mixture of sodium hydroxide and water glass. The foamed light mixed soil is prepared by replacing cement with the alkali-activated industrial solid waste lithium slag, so that the lithium slag accumulation can be effectively treated; the alkali activator, the lithium slag and the waste slurry have a synergistic effect, so that the mechanical property and durability of the foamed light soil are improved, and meanwhile, the cost of the foamed light soil can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of foamed lightweight soil, and particularly relates to an alkali-activated lithium slag-based foamed lightweight mixed soil using waste mud and a preparation method thereof. Background Art

[0002] Foam lightweight soil is a lightweight porous cement-based material formed by mixing cement, water and other admixtures and additives in a certain mass ratio and stirring them evenly with the foam prepared by the foaming agent aqueous solution, and then hardening it. It has the advantages of light weight, good fluidity and strong uprightness. It is currently widely used in soft foundation treatment of highway engineering, road widening, backfilling of bridge abutments, steep slope embankments, backfilling of pipe pits and other fields.

[0003] At present, most foamed lightweight soils are still prepared with cement as the main raw material, which has high production costs and the use of large amounts of cement has a great impact on the environment. At the same time, foamed lightweight soils prepared with pure cement are prone to cracking and have large drying shrinkage. Some scholars have used raw materials such as sand and clay to partially replace cement to prepare foamed lightweight soils, which has reduced the use of cement to a certain extent, but will lead to a decrease in the strength of foamed lightweight soils, poor impermeability, poor anti-scouring ability, etc., which will affect the application of foamed lightweight soils in actual engineering.

[0004] Lithium slag is industrial waste slag produced by processes such as high-temperature roasting and acid roasting at 1100-1200℃, atmospheric pressure water leaching, neutralization and impurity removal, and liquid-solid separation of lithium concentrate raw materials. The industrial solid waste slag (referred to as lithium slag) produced by lithium extraction is generally piled up or landfilled. The residual sulfides and harmful elements have great harm to the surrounding soil and water quality. The research on the resource utilization of lithium slag in my country started late, and the utilization methods of lithium slag are not diversified enough, which makes the utilization rate of lithium slag in my country extremely low. Therefore, improving the resource utilization of lithium slag is of great significance to protecting the environment and promoting the sustainable development of resources. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide an alkali-activated lithium slag-based foamed lightweight mixed soil and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is: An alkali-activated lithium slag-based foamed lightweight mixed soil, which is made from the following raw materials in parts by weight: 9.6-21.6 parts of lithium slag, 7.2-12 parts of waste mud, 0.35-0.75 parts of bubble groups, 0-0.6 parts of waterproofing agent, and 1-2.2 parts of alkali activator; The alkaline activator is a mixture of sodium hydroxide and water glass.

[0007] As a further improvement, it is made of raw materials comprising the following parts by weight: 13.2-18.4 parts of lithium slag, 9.6-10.8 parts of waste mud, 0.5-0.7 parts of bubble groups, 0.5-0.6 parts of waterproofing agent, and 1.3-1.8 parts of alkali activator.

[0008] As a further improvement, the lithium slag is industrial waste residue produced by producing lithium carbonate from lithium concentrate through roasting, water leaching, neutralization and impurity removal, and liquid-solid separation.

[0009] As a further improvement, the mass fraction of silicon dioxide in the lithium slag is greater than 40%, the mass fraction of aluminum oxide is greater than 20%, the mass fraction of calcium oxide is 2-8%, and the mass fraction of magnesium oxide is 0-2%.

[0010] As a further improvement, the waste mud is generated by bored pile construction and has a water content of 42%-46%.

[0011] As a further improvement, the water-to-solid ratio of the foam lightweight mixed soil is (0.3-0.4):1.

[0012] As a further improvement, the bubble group is formed by a foaming agent and water through a foaming machine.

[0013] As a further improvement, the preparation method of the alkaline activator is: adjusting the modulus of water glass to 1-1.2 with sodium hydroxide.

[0014] The present invention also provides a method for preparing the alkali-activated lithium slag-based foamed lightweight mixed soil, comprising the following steps: S1: mixing lithium slag and alkali activator evenly to form a mixed dry material; S2: adding the waste slurry into the dry mixed material to form a mixed lithium slag slurry; S3: adding a bubble group to the mixed alkali-activated lithium slag slurry and stirring evenly to obtain a mixed mixture; S4: The mixed slurry is poured and cured to obtain alkali-activated lithium slag-based foamed lightweight mixed soil.

[0015] As a further improvement, a waterproofing agent is also added to S1.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses alkali to activate industrial solid waste lithium slag to replace cement to prepare foamed lightweight mixed soil, which can effectively treat lithium slag accumulation; the alkali activator, lithium slag and waste mud work synergistically to improve the mechanical properties and durability of the foamed lightweight soil, and at the same time can reduce the cost of the foamed lightweight soil.

[0017] The content of silicon dioxide and aluminum oxide in lithium slag is very high, and it has certain volcanic ash activity. The addition of lithium slag changes the type of material hydration products, from calcium-rich CSH to aluminum-rich CASH, and the type composition changes from single to diverse. Lithium slag can promote the early hydration of lightweight soil and improve the mechanical properties of lightweight soil. The addition of lithium slag can also improve the density of lightweight soil and reduce its drying shrinkage.

[0018] The alkali-activated lithium slag-based foamed lightweight mixed soil of the present invention is lightweight, high-strength and has good anti-seepage performance. The raw materials are simple and easy to obtain, and the waste mud can be used on site, without consuming a lot of manpower and material resources. The construction process is simple, the fluidity is good, and it is pumpable, and can be directly pumped to narrow spaces, limited sites and other areas that are difficult to compact and fill.

[0019] The alkali-activated lithium slag-based foamed lightweight mixed soil of the present invention not only expands the resource utilization channels of industrial waste lithium slag and improves the utilization rate of lithium slag, but also can fully utilize the waste impurity mud at the construction site and reduce the accumulation and waste of soil resources. It is a new type of green and environmentally friendly foamed lightweight soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The present invention is a schematic flow diagram of a method for preparing alkali-activated lithium slag-based foamed lightweight mixed soil according to an embodiment; Figure 2 is an electron microscope photograph of the lithium slag used in the embodiment of the present invention; Figure 3 This is an electron microscope photograph of the lithium slag-based foamed lightweight mixed soil prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0024] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0025] In some specific embodiments, the alkali-activated lithium slag-based foamed lightweight mixed soil of the present invention is made of the following raw materials in parts by weight: 9.6-21.6 parts (preferably 13.2-18.4 parts) of lithium slag, 7.2-12 parts (preferably 9.6-10.8 parts) of waste mud, 0.35-0.75 parts (preferably 0.5-0.7 parts) of bubble groups, 0-0.6 parts (preferably 0.5-0.6 parts) of waterproofing agent, and 1-2.2 parts (preferably 1.3-1.8 parts) of alkali activator.

[0026] In some embodiments, the lithium slag is industrial waste slag produced by processes such as high-temperature roasting and acid roasting at 1100-1200°C, atmospheric water leaching, neutralization and impurity removal, and liquid-solid separation of lithium concentrate raw materials. The mass fraction of silicon dioxide in the lithium slag is greater than 40% (for example, 40-70%), the mass fraction of aluminum oxide is greater than 20% (for example, 20-30%), the mass fraction of calcium oxide is 2-8%, and the mass fraction of magnesium oxide is 0-2%. In some embodiments, the density of the lithium slag is 2.4-2.5g / m 3 , more than 60% of the lithium slag particles have a particle size less than 0.08mm, and the maximum particle size is no more than 2.75mm.

[0027] In some embodiments, the waste mud is produced by bored pile construction, mainly clay, and its water content is 42%-46%. In the following embodiments, the water-solid ratio of the foamed lightweight mixed soil is (0.3-0.4): 1. If the water content of the waste mud is insufficient, it is adjusted by adding water. The water-solid ratio is the ratio of water to solid materials, that is, the ratio of water in the foamed lightweight mixed soil to the sum of the weight of lithium slag, alkali activator, and waste mud dry weight.

[0028] In some embodiments, the bubble group can be prepared by conventional methods, specifically, a foaming agent and water are prepared by a foaming machine, wherein the preparation process is to add the foaming agent to water according to the dilution multiple to dilute the foaming liquid; and a fine and stable bubble group is produced by the foaming machine. The bubble group is substantially free of water. In some embodiments, the foaming agent is LG-2258 foaming agent, and the dilution multiple (mass ratio) is foaming agent: water = 1: (50-60).

[0029] In some embodiments, the alkaline activator is a mixture of sodium hydroxide and water glass. The preparation method is: adjust the modulus of water glass to 1-1.2 with sodium hydroxide. If the modulus is too large or too small, it will affect its excitability, resulting in a decrease in strength. The excitation effect within the above modulus range is better than other moduli. When using sodium hydroxide alone or water glass alone as an activator, the lithium slag has a certain volcanic ash activity, but the activity is not very high, and the excitation effect on the lithium slag is not obvious; but sodium hydroxide and water glass form a mixture, which can provide a stronger alkaline environment, stimulate the activity of lithium slag to a greater extent, and promote the formation of CSH gel. The two work together to accelerate the hydration process.

[0030] In some embodiments, the water repellent is sodium methyl silicate.

[0031] Lithium slag is a product of high-temperature calcination. Under appropriate conditions, it can show volcanic ash activity and undergo the following chemical reactions: CaO+H2O →Ca(OH)2 Ca(OH)2+ SiO2+H2O →CaO·SiO2·H2O Ca(OH)2+Al2O3+H2O →CaO·Al2O3·H2O Lithium slag contains active silicon oxide and aluminum oxide, which can react with calcium hydroxide and sodium hydroxide, that is, the following reaction can occur in an alkaline environment: Al2O3+4SiO2+NaOH+H2O→Na2O·Al2O3·4SiO2·2H2O Al2O3+3SiO2+Ca(OH)2+2H2O→CaO·A12O3·3SiO2·3H2O The product of the above reaction is zeolite mineral hydrated sodium aluminosilicate or hydrated calcium aluminosilicate. The calcium zeolite is rod-shaped or columnar, with a relatively dense structure and high strength. These two types of bodies can interweave and connect with each other during the hydration process to form a strong and dense spatial structure, so the hydration product should have high strength.

[0032] The water glass in the alkaline activator mainly provides two functions: first, it provides an alkaline environment. The strong alkaline component Na2O in the water glass can break some Ca-O bonds, Si-O bonds and Al-O in the raw materials, dissolving elements such as calcium, silicon, and aluminum; second, it directly participates in the polymerization reaction as a reactant.

[0033] Although the silicon oxide and aluminum oxide contents of lithium slag are very high, its calcium oxide content is very low. In a single alkali excitation environment, it cannot well excite the strength characteristics. In the absence of any admixture, the hydration activity is extremely low and it does not have gelling properties. The waste mud used in the present invention is mainly clay-based and has a certain calcium oxide content, which can make up for the defect of low calcium oxide content of lithium slag and better excite the activity of lithium slag.

[0034] The invention mainly utilizes the volcanic ash activity of lithium slag and adopts a specific alkaline activator to activate the volcanic ash activity of lithium slag to form a gelling curing agent to replace cement to solidify the waste mud, thereby achieving the purpose of waste utilization.

[0035] In some embodiments, the preparation method of the alkali-activated lithium slag-based foamed lightweight mixed soil of the present invention comprises the following steps: S1: Mix lithium slag and alkali activator (and waterproofing agent) evenly to form a mixed dry material; S2: adding the waste slurry into the dry mixed material to form a mixed lithium slag slurry; S3: adding a bubble group to the mixed alkali-activated lithium slag slurry (preparing a foaming liquid on site, foaming the prepared bubble group in real time and passing it into the slurry), stirring evenly to obtain a mixed mixture; S4: The mixed slurry is poured and cured to obtain alkali-activated lithium slag-based foamed lightweight mixed soil.

[0036] In some embodiments, the wet density of the alkali activated lithium slag based foamed lightweight mixed soil is 1000 kg / m 3 -1200kg / m 3 The fluidity is (160-200) mm, and the compressive strength is greater than 2.0MPa under 28-day natural curing conditions.

[0037] The alkali-activated lithium slag-based foamed lightweight mixed soil of the present invention can be applied to roadbed, pipe pit backfill, embankment engineering, flood control engineering, etc., and can be directly poured through pipeline pumping.

[0038] The raw material parameters used in the embodiments of the present invention are as follows: Lithium slag: industrial waste slag produced by the processes of 1100-1200℃ high temperature roasting and acid roasting, atmospheric pressure water leaching, neutralization and impurity removal, liquid-solid separation, etc. of lithium concentrate raw materials (spodumene, montmorillonite and other lithium-containing ores obtained by flotation, mainly lithium carbonate). After drying at 105℃, the maximum particle size is less than or equal to 2.75mm, and more than 60% is less than 0.08mm; the mass fraction of SiO2 in the lithium slag is 63.2%, the mass fraction of Al2O3 is 21%, the mass fraction of CaO is 3.32%, and the mass fraction of MgO is 0.39%; the density of lithium slag is 2.4-2.5g / m 3 ; Waste mud: produced by bored pile construction, with a water content of 42%-46%; The foaming agent in the bubble group is LG-2258 foaming agent, and the dilution ratio (mass ratio) is foaming agent: water = 1:55. Among them, LG-2258 foaming agent: foaming ratio 27-30 times, 1h settlement distance ≤50mm, 1h water seepage rate ≤70%, meeting the "Foaming Agent for Foamed Concrete" JC / T 2199-2013. Its preparation process is to add the foaming agent into the water according to the dilution ratio to dilute it to form a foaming liquid; put the water inlet plastic pipe of the foaming machine into the mixed foaming liquid; turn on the foaming machine switch, first turn on the water pump, and then turn on the air pump to release fine and stable bubble groups; Alkali activator: a mixture of sodium hydroxide and water glass, preparation method: adjust the modulus of water glass to 1 with sodium hydroxide; Waterproofing agent: sodium methyl silicate.

[0039] Example 1 The raw materials for preparing the lithium slag-based foamed lightweight mixed soil of this embodiment include: 13.2 parts of lithium slag, 10.8 parts of waste mud (water content 42%-46%), 0.6 parts of bubble groups, and 1.3 parts of alkali activator.

[0040] The preparation method of the lithium slag-based foamed lightweight mixed soil of the present embodiment is carried out according to the following steps: Step 1: First, lithium slag and alkali activator are put into a stirring device according to proportion, and stirred for 2 minutes to evenly mix the raw materials to form a mixed dry material; Step 2: Add the waste mud into the dry mixture in proportion and stir for 3 minutes to form a mixed lithium slag slurry; Step 3: Add the bubble group to the slurry and stir for 3 minutes until it is evenly mixed to obtain a mixed material; Step 4: Immediately pour the mixed slurry into the specimen mold, seal it with plastic film, demould it after 2 days, and cure it in a natural state for 28 days to obtain the alkali-activated lithium slag-based foamed lightweight mixed soil using waste mud.

[0041] Example 2 The raw materials for preparing the lithium slag-based foamed lightweight mixed soil of this embodiment include: 14.4 parts of lithium slag, 9.6 parts of waste mud (water content 42%-46%), 0.6 parts of bubble groups, and 1.4 parts of alkali activator.

[0042] The preparation method of the alkali-activated lithium slag-based foamed lightweight mixed soil in this embodiment is the same as the preparation method in Example 1.

[0043] Example 3 The raw materials for preparing the lithium slag-based foamed lightweight mixed soil of this embodiment include: 15.6 parts of lithium slag, 8.4 parts of waste mud (water content 42%-46%), 0.6 parts of bubble groups, and 1.6 parts of alkali activator.

[0044] The preparation method of the alkali-activated lithium slag-based foamed lightweight mixed soil in this embodiment is the same as the preparation method in Example 1.

[0045] Example 4 The raw materials for preparing the lithium slag-based foamed lightweight mixed soil of this embodiment include: 16.8 parts of lithium slag, 7.2 parts of waste mud (water content 42%-46%), 0.6 parts of bubble groups, and 1.7 parts of alkali activator.

[0046] The preparation method of the lithium slag-based foamed lightweight mixed soil in this embodiment is the same as the preparation method in Example 1.

[0047] Example 5 The raw materials for preparing the lithium slag-based foamed lightweight mixed soil of this embodiment include: 18.4 parts of lithium slag, 9.6 parts of waste mud (water content 42%-46%), 0.6 parts of bubble groups, 0.6 parts of waterproofing agent, and 1.8 parts of alkali activator.

[0048] The preparation method of the lithium slag-based foamed lightweight mixed soil of the present embodiment is carried out according to the following steps: Step 1: First, lithium slag, alkali activator and waterproofing agent are put into a stirring device in proportion and stirred for 2 minutes to evenly mix the raw materials to form a mixed dry material; Step 2: Add the waste mud into the dry mixture in proportion and stir for 3 minutes to form a mixed lithium slag slurry; Step 3: Add the bubble group to the slurry and stir for 3 minutes until it is evenly mixed to obtain a mixed material; Step 4: Immediately pour the mixed slurry into the specimen mold, seal it with plastic film, demould it after 2 days, and cure it in a natural state for 28 days to obtain the alkali-activated lithium slag-based foamed lightweight mixed soil using waste mud.

[0049] Figure 2 is an electron microscope photograph of the lithium slag used in the embodiment of the present invention, Figure 3 This is an electron microscope photograph of the lithium slag-based foamed lightweight mixed soil prepared in Example 5 of the present invention. The addition of lithium slag improves the compactness of the lightweight soil.

[0050] Comparative Example 1 Weigh by weight: 12 parts of cement, 12 parts of waste mud (water content 42%-46%), and 0.6 parts of bubble group.

[0051] The preparation method of the foamed lightweight soil of this comparative example is carried out according to the following steps: Step 1: Put cement into the mixing device; Step 2: Add the waste mud to cement in proportion and stir for 3 minutes to form cement soil slurry; Step 3: Add the bubble group to the slurry and stir for 3 minutes until it is evenly mixed to obtain a mixed material; Step 4: Immediately pour the mixed slurry into the specimen mold, seal it with plastic film, demould it after 2 days, and cure it in a natural state for 28 days to obtain the foamed lightweight mixed soil.

[0052] Comparative Example 2 Weigh by weight: 12 parts of cement, 12 parts of waste mud (water content 42%-46%), 0.6 parts of bubble group, 2.4 parts of fly ash, and 0.11 parts of alkali activator.

[0053] The method for preparing the foamed lightweight mixed soil mixed with fly ash in this comparative example is carried out according to the following steps: Step 1: First, put fly ash and cement into a mixing device according to proportion and stir for 2 minutes to evenly mix the raw materials to form a mixed dry mix; Step 2: Add the waste mud into the dry mix according to the proportion and stir for 3 minutes to form a mixed cement soil slurry; Step 3: Add the bubble group to the slurry and stir for 3 minutes until it is evenly mixed to obtain a mixed material; Step 4: Immediately pour the mixed slurry into the specimen mold, seal it with plastic film, demould it after 2 days, and cure it in a natural state for 28 days to obtain the foamed lightweight mixed soil mixed with fly ash.

[0054] Comparative Example 3 Weigh by weight: 12 parts of cement, 12 parts of waste mud (water content 42%-46%), 0.6 parts of bubble group, 4.8 parts of fly ash, and 0.11 parts of alkali activator.

[0055] The preparation method of the foamed lightweight mixed soil mixed with fly ash in this comparative example is the same as the preparation method in comparative example 2.

[0056] Comparative Example 4 The only difference from Example 5 is that no alkaline activator is added in this comparative example.

[0057] Comparative Example 5 The only difference from Example 5 is that the alkali activator of this comparative example is a mixture of sodium hydroxide and water glass (modulus 1.5).

[0058] Comparative Example 6 The only difference from Example 5 is that no waste mud is added in this comparative example.

[0059] The light soil prepared in the above-mentioned Examples 1-5 and Comparative Examples 1-3 was tested. The specific tests are as follows: 1. Determine the slurry flow value with reference to CJJ / T 177-2012 Technical Specification for Bubble Mixed Lightweight Soil Filling; 2. Refer to JG / T 266-2011 "Foamed Concrete" to measure the dry bulk density and 28d compressive strength of the specimen with a size of 100mm×100mm×100mm; 3. Refer to JG / T 266-2011 "Foamed Concrete" to measure the water absorption rate of the specimen with the size of 100mm×100mm×100mm.

[0060] The properties of the lightweight soils prepared in Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0061] Table 1

[0062] As can be seen from Table 1, the alkali-activated lithium slag-based foamed lightweight soil of the embodiment has good fluidity, light weight, high strength, and good anti-permeability. Its fluidity is within (160-200) mm, which meets the pumping requirements; the compressive strength under 28d natural curing can reach more than 1.79MPa, preferably more than 2.0MPa. The unconfined compressive strength of Examples 1 and 2 is slightly lower than that of Comparative Examples 2 and 3, but the price of lithium slag is much lower than that of fly ash; the lightweight mixed soil can make full use of industrial solid waste lithium slag, improve its basic properties, and has great economic benefits.

[0063] In Examples 3 and 4, as the amount of lithium slag increases, the activating effect of the alkaline activator is not obvious during the hydration process, and there are too many free lithium slag particles in the product, resulting in reduced strength. In Example 5, more waterproofing agent is added, which effectively prevents the entry of water molecules. The lithium slag particles have strong water absorption. When the water molecules are blocked, the solid lithium slag particles can show a certain strength, resulting in an increase in strength, so the water absorption rate is also the lowest.

[0064] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. An alkali-activated lithium slag-based foamed lightweight mixed soil, characterized in that: The invention is prepared from the following raw materials in parts by weight: 9.6-21.6 parts of lithium slag, 7.2-12 parts of waste mud, 0.35-0.75 parts of bubble groups, 0-0.6 parts of waterproofing agent, and 1-2.2 parts of alkali activator; The alkaline activator is a mixture of sodium hydroxide and water glass.

2. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1, characterized in that: The invention is prepared from the following raw materials in parts by weight: 13.2-18.4 parts of lithium slag, 9.6-10.8 parts of waste mud, 0.5-0.7 parts of bubble groups, 0.5-0.6 parts of waterproofing agent and 1.3-1.8 parts of alkali activator.

3. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1 or 2, characterized in that: The lithium slag is industrial waste residue produced by producing lithium carbonate through roasting, water leaching, neutralization and impurity removal, and liquid-solid separation of lithium concentrate.

4. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1 or 2, characterized in that: The lithium slag has a silicon dioxide mass fraction greater than 40%, a aluminum oxide mass fraction greater than 20%, a calcium oxide mass fraction of 2-8%, and a magnesium oxide mass fraction of 0-2%.

5. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1 or 2, characterized in that: The waste mud is generated by bored pile construction, and its water content is 42%-46%.

6. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 5, characterized in that: The water-to-solid ratio of the foam lightweight mixed soil is (0.3-0.4):

1.

7. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1 or 2, characterized in that: The bubble group is formed by a foaming agent and water through a foaming machine.

8. The alkali-activated lithium slag-based foamed lightweight mixed soil according to claim 1 or 2, characterized in that: The preparation method of the alkaline activator is: adjusting the modulus of water glass to 1-1.2 with sodium hydroxide.

9. A method for preparing the alkali-activated lithium slag-based foamed lightweight mixed soil according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: mixing lithium slag and alkali activator evenly to form a mixed dry material; S2: adding the waste slurry into the dry mixed material to form a mixed lithium slag slurry; S3: adding a bubble group to the mixed alkali-activated lithium slag slurry and stirring evenly to obtain a mixed mixture; S4: The mixed slurry is poured and cured to obtain alkali-activated lithium slag-based foamed lightweight mixed soil.

10. The preparation method according to claim 9, characterized in that: A water-repellent is also added to S1.

Images