A large amount of lithium slag foam soil and a preparation method thereof

Abstract

The present application relates to the technical field of foam soil, and particularly relates to a large-mixing-amount lithium slag foam soil and a preparation method thereof. According to mass percentages, raw materials of the large-mixing-amount lithium slag foam soil include a foaming agent 0.5-5%, a solidifying agent 7-25%, a composite soil 65-85% and an excitation agent 5-15%; according to mass percentages, the solidifying agent includes steel slag 0-20%, mineral slag 30-70%, first-pass lithium slag 0-15% and second-pass lithium slag 20-50%; and according to mass percentages, the composite soil includes second-pass lithium slag 60-80%, fly ash 10-20% and soil 0-30%. The present application uses lithium slag to prepare the solidifying agent and the composite soil, and uses the same to produce the foam soil, so that the use amount of cement can be reduced, land resources can be saved, and a large amount of lithium slag waste can be absorbed. The present application has reasonable raw material composition and ratio, and can greatly increase the mixing amount of the lithium slag in the foam soil while ensuring the performance of the foam soil.

Description

Technical Field

[0001] This invention relates to the field of foamed soil technology, and in particular to a foamed soil with a large amount of lithium slag and its preparation method. Background Technology

[0002] Mineral resource development generates a large amount of solid waste. Mineral processing tailings are a major type of solid waste with high industrial output and low comprehensive utilization rate. They are typically left in the open after mineral processing, impacting not only the environment and safety but also the survival and development of enterprises and industries. The flotation of lepidolite and the production of lithium carbonate generate large amounts of tailings waste, which continues to increase annually with the rapid development of the lithium battery industry. Due to the narrow particle size distribution, high water content, and low intrinsic value of raw lithium slag, it is currently not effectively utilized, with an overall utilization rate of less than 20%. Most of it is disposed of through stockpiling, occupying large amounts of land and wasting resources. Currently, research and applications of lithium slag mainly focus on the preparation of cement mortar, concrete, and other building materials, as well as the preparation of ceramic materials. Lithium slag has a high silicon and aluminum content and possesses certain pozzolanic activity, which can improve the mechanical properties and carbonation performance of concrete. However, lithium tailings also contain large amounts of alkali metals such as sodium and potassium, which can easily cause problems such as efflorescence and efflorescence on the concrete surface, limiting its large-scale application in concrete.

[0003] Foamed soil is a new type of lightweight filling material prepared by uniformly mixing foam, cementitious materials, and soil in a certain proportion and then hardening it. It features light weight, high fluidity, thermal insulation, adjustable strength, and good construction performance, and is widely used in roadbed backfilling, soft soil subgrade load reduction, tunnel grouting, and other projects. Ordinary foamed soil mainly consists of cement, soil, and foam. Cement is a high-energy-consuming and high-polluting industry, and the foamed soil prepared from it has low early strength and is prone to cracking. Furthermore, the preparation of foamed soil consumes a large amount of land resources. Although there is research on using lithium slag in foamed concrete, it requires calcination modification of the lithium slag to change its phase composition, increasing production costs.

[0004] Therefore, providing a method for preparing foamed soil with high lithium slag content and increasing the amount of undisturbed lithium slag added to the foamed soil can, on the one hand, avoid the increased cost caused by calcination treatment, and on the other hand, can dispose of a large amount of lithium slag waste, improve the utilization value of lithium slag, and reduce the amount of cement used. This is of great significance to the fields of foamed soil and environmental protection technology. Summary of the Invention

[0005] Based on the above, the present invention provides a high-volume lithium slag foamed soil and its preparation method.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of this invention is a high-volume lithium slag foamed soil, which, by mass percentage, comprises 0.5% to 5% foaming agent, 7% to 25% curing agent, 65% to 85% composite soil, and 5% to 15% activator.

[0008] The curing agent comprises, by mass percentage, 0%–20% steel slag, 30%–70% blast furnace slag, 0%–15% primary lithium slag, and 20%–50% secondary lithium slag;

[0009] The composite soil comprises, by mass percentage, 60%–80% secondary lithium slag, 10%–20% fly ash, and 0%–30% soil;

[0010] The activator is a mixture of carbide slag, gypsum, aluminum sulfate and sodium carbonate in a mass ratio of (3-4):(4-5):(0-0.5):(0.5-1.5).

[0011] The second technical solution of the present invention is a method for preparing the above-mentioned high-content lithium slag foamed soil, comprising the following steps:

[0012] The foaming agent, curing agent, composite soil and activator are mixed evenly according to the mass percentage to obtain the foamed soil.

[0013] The third technical solution of this invention is the application of the above-mentioned high-volume lithium slag foamed soil in building construction, roadbed, trench backfilling and tunnel engineering.

[0014] Invention concept:

[0015] Unrefined lithium slag contains abundant elements such as silicon, aluminum, magnesium, calcium, potassium, and sodium, similar to the elemental composition of soil, allowing it to be used directly as soil. Unrefined lithium slag contains a large amount of insoluble salts, including calcium sulfate and silicon-aluminum oxides. These components can form the soil skeleton, and substances like calcium sulfate can create a cementing effect between soil particles. Using unrefined lithium slag, soil, and fly ash as a composite soil can effectively improve the particle size distribution, making the soil structure denser, increasing the friction and interlocking force between soil particles, and improving the stability of the composite soil. The presence of a large amount of alkali metals in lithium slag can increase the alkalinity of the slurry, which is beneficial for activating the slag activity and fully utilizing the alkaline effect of the alkali metals in the lithium slag, achieving efficient utilization of lithium slag.

[0016] Based on the analysis of lithium slag composition, this invention prepares composite soil by mixing raw lithium slag, soil and fly ash, optimizes the various properties of the composite soil, and then prepares foamed soil, effectively solving the problems of narrow particle size distribution, high water content and low utilization rate of raw lithium slag.

[0017] The present invention discloses the following technical effects:

[0018] This invention utilizes lithium slag to prepare a curing agent and composite soil, which is then used to produce foamed soil. This reduces cement usage, conserves land resources, and can also dispose of a large amount of lithium slag waste, contributing to the achievement of the "dual carbon" goal. The raw material composition and proportions of this invention are rational, significantly increasing the amount of undisturbed lithium slag added to the foamed soil while ensuring its performance, thereby enhancing the utilization value of lithium slag.

[0019] The process steps of this invention are simple and easy to promote and apply. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an XRD pattern of a lithium slag from the present invention.

[0022] Figure 2 This is the XRD pattern of the second-stage lithium slag of the present invention.

[0023] Figure 3 This is a flow chart of the curing agent preparation process of the present invention.

[0024] Figure 4 This is a flowchart of the preparation process of the activator of the present invention.

[0025] Figure 5 This is a flow chart of the foamed soil preparation process of the present invention. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] The first aspect of this invention provides a high-volume lithium slag foamed soil, wherein the raw materials, by mass percentage, include 0.5% to 5% foaming agent, 7% to 25% curing agent, 65% to 85% composite soil, and 5% to 15% activator;

[0032] The curing agent comprises, by mass percentage, 0%–20% steel slag, 30%–70% blast furnace slag, 0%–15% primary lithium slag, and 20%–50% secondary lithium slag;

[0033] The composite soil comprises, by mass percentage, 60%–80% secondary lithium slag, 10%–20% fly ash, and 0%–30% soil;

[0034] The activator is a mixture of carbide slag, gypsum, aluminum sulfate and sodium carbonate in a mass ratio of (3-4):(4-5):(0-0.5):(0.5-1.5).

[0035] The fly ash is a solid waste discharged from coal-fired power plants, and can be wet ash discharge and / or dry ash discharge.

[0036] Secondary lithium slag acts as a framework and binder in composite soil.

[0037] In a preferred embodiment of the present invention, the foaming agent is a mixture of water, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, sludge protein, and nano calcium carbonate in a mass ratio of (8-10):(3.5-5):(3.5-5):(3-4):(0.05-0.2).

[0038] In a preferred embodiment of the present invention, the sludge protein refers to a concentrated protein solution extracted from the biological cells of sludge by breaking them down using physical or chemical methods, with a pH value of 11.5 to 13.5 and a protein content of 25% to 35%.

[0039] In a preferred embodiment of the present invention, the lithium slag is a solid waste generated during the flotation of lepidolite, and its main chemical components are: Na2O 1%–4%, K2O 1%–3%, SiO2 50%–80%, and Al2O3 7%–11%.

[0040] In a preferred embodiment of the present invention, the secondary lithium slag is a solid waste generated during the production of lithium carbonate from lepidolite, and its main chemical components are Na2O 1%–4%, K2O 1%–3%, SiO2 20%–40%, Al2O3 10%–15%, MgO 0%–2%, CaO 15%–25%, and SO3 10%–20%.

[0041] In a preferred embodiment of the present invention, the soil is at least one of sandy soil, silty soil, mud, clay, loess, planting soil, and fill soil.

[0042] A second aspect of the present invention provides a method for preparing the above-mentioned high-content lithium slag foamed soil, comprising the following steps:

[0043] The foaming agent, curing agent, composite soil and activator are mixed evenly according to the mass percentage to obtain the foamed soil.

[0044] In a preferred embodiment of the present invention, the mixing is specifically achieved by using a two-stage continuous mixing method of a twin-shaft mixer and a high-speed activation mixer to mix evenly.

[0045] In a preferred embodiment of the present invention, the curing agent is obtained by uniformly mixing steel slag, ore slag, primary lithium slag and secondary lithium slag in a mass percentage.

[0046] The composite soil is obtained by uniformly mixing secondary lithium slag, fly ash, and soil according to mass percentages.

[0047] The activator is obtained by uniformly mixing carbide slag, gypsum, aluminum sulfate and sodium carbonate in a uniform mass ratio.

[0048] The foaming agent is prepared by adding water, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, sludge protein, and nano calcium carbonate into a foaming device in a certain mass ratio.

[0049] A raw material storage area, a curing agent silo, an activator silo, a foam generating device, and a mixing system can be set up at the foamed soil preparation station. The proportions of foaming agent, curing agent, composite soil, and activator can be adjusted according to engineering needs to obtain foamed soil with different strengths.

[0050] The third aspect of this invention provides the application of the above-mentioned high-volume lithium slag foamed soil in building construction, roadbeds and tunnels.

[0051] Unless otherwise specified, the "%" mentioned in this invention refers to a percentage by mass.

[0052] Unless otherwise specified, all raw materials used in the embodiments of this invention can be obtained through commercial channels.

[0053] The steel slag used in the embodiments and comparative examples of this invention is a solid waste mainly composed of silicates and aluminoferrites obtained from steelmaking in converters or electric arc furnaces of steel plants. Its performance indicators meet the relevant provisions of YB / T 022-2008 "Steel Slag for Use in Cement" and GB / T 20491-2017 "Steel Slag Powder for Use in Cement and Concrete".

[0054] The slag used in the embodiments and comparative examples of this invention is a molten material mainly composed of aluminosilicates produced during the blast furnace smelting of pig iron. After being quenched and granulated, it forms a potential hydraulic material. Its performance indicators meet the relevant provisions of GB / T 203-2008 "Granulated Blast Furnace Slag for Cement" and GB / T 18046-2017 "Physical and Chemical Blast Furnace Slag Powder for Cement, Mortar and Concrete".

[0055] The lithium slag used in this embodiment of the invention is undisturbed lithium slag, a solid waste generated during the flotation of lepidolite, with the main chemical components being: Na₂O 1%–4%, K₂O 1%–3%, SiO₂ 50%–80%, and Al₂O 37%–11%. The XRD pattern of this lithium slag is shown below. Figure 1 As shown.

[0056] The secondary lithium slag used in the embodiments and comparative examples of this invention is undisturbed secondary lithium slag, a solid waste generated during the production of lithium carbonate from lepidolite. Its main chemical components are: Na₂O 1%–4%, K₂O 1%–3%, SiO₂ 20%–40%, Al₂O₃ 10%–15%, MgO 0%–2%, CaO 15%–25%, and SO₃ 10%–20%. The XRD pattern of this secondary lithium slag is shown below. Figure 2 As shown.

[0057] The fly ash used in the embodiments and comparative examples of this invention is dry-discharged fly ash, with a water requirement ratio of less than 105%, a 28-day activity index greater than 70%, and a characteristic particle size d. 90 Less than 95μm.

[0058] The main mineral components of the loess used in the embodiments of the present invention are quartz, feldspar, calcite, mica, illite, montmorillonite, etc., with a particle size of less than 0.05 mm; the main mineral components of the clay are kaolinite, montmorillonite, diaspore, illite, etc.; the main mineral components of the silt are illite, montmorillonite, kaolinite, with an organic matter content of 2% to 12% and a water content of 50% to 80%.

[0059] The calcium carbide slag used in the embodiments and comparative examples of this invention is the solid waste residue after obtaining acetylene by hydrolysis of calcium carbide, and its main component is calcium hydroxide.

[0060] The gypsum used in the embodiments and comparative examples of this invention is a solid waste with calcium sulfate as the main component discharged during industrial production, including at least one of desulfurized gypsum, phosphogypsum, titanium gypsum, citric acid residue, etc., and its performance indicators meet GB / T21371-2019 "Industrial by-product gypsum for use in cement".

[0061] The performance indicators of aluminum sulfate used in the embodiments and comparative examples of this invention meet the HG / T 2225-2001 standard "Industrial Aluminum Sulfate".

[0062] The performance indicators of sodium carbonate used in the embodiments and comparative examples of this invention meet the GB 210-92 standard for industrial sodium carbonate.

[0063] The foaming agent used in the embodiments and comparative examples of this invention is a mixture of water, sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, sludge protein, and nano calcium carbonate in a mass ratio of 8:4.5:4:3:0.1; wherein the sludge protein refers to a protein concentrate extracted from biological cells by breaking them down using physical or chemical methods, with a pH value of 11.5 to 13.5 and a protein content of 25% to 35%.

[0064] The process flow diagram for preparing the curing agent of this invention is as follows: Figure 3 As shown.

[0065] The process flow diagram for preparing the activator of this invention is as follows: Figure 4 As shown.

[0066] The process flow diagram for preparing foamed soil according to this invention is as follows: Figure 5 As shown.

[0067] Example 1

[0068] In this embodiment, the curing agent is composed of 20% steel slag, 60% ore slag, and 20% secondary lithium slag;

[0069] The activator is a mixture of carbide slag, gypsum, aluminum sulfate and sodium carbonate in a mass ratio of 3:4:0.5:1;

[0070] The composite soil is composed of 60% lithium slag, 10% fly ash, and 30% loess;

[0071] Foamed soil is composed of 20% curing agent, 67% composite soil, 11% activator and 2% foaming agent.

[0072] The preparation method of foamed soil in this embodiment is as follows:

[0073] Step 1, A: Grind steel slag, mineral slag, and secondary lithium slag separately to a specific surface area of ​​500-550 m². 2 / kg (content of particles smaller than 325 mesh ≤1%), mixed evenly according to the ratio to obtain curing agent, transported by tanker to curing agent silo, and then entered into the mixing system through a weighing device.

[0074] B: Mix and grind the carbide slag and gypsum until the specific surface area is 400-450 m². 2 / kg (particles smaller than 325 mesh content ≤5%), mixed evenly with sodium carbonate and aluminum sulfate to obtain activator, which is transported by tanker to activator silo and then enters the mixing system through a weighing device.

[0075] C: The two-stage lithium slag, loess and fly ash are mixed on site to obtain composite soil, which is then sent to the mixing system via a belt conveyor. The belt is equipped with a weighing system to control the quality of the composite soil.

[0076] D: Load the foaming agent into the foaming device, prepare foam according to the required amount of foam, and then send the foam into the mixing system.

[0077] Step 2: Steps A, B, C, and D in Step 1 are performed simultaneously. The mixing system uses a two-stage continuous mixing process: a twin-shaft mixer and a high-speed activation mixer. The first stage (twin-shaft mixer) operates at a speed of 52 rpm for 90 seconds, while the second stage (high-speed activation mixer) operates at a speed of 460 rpm for 40 seconds. This helps to promote uniform mixing and stable properties of the foamed soil. After all materials (curing agent + activator + composite soil + foaming agent) are mixed, foamed soil is obtained.

[0078] Example 2

[0079] In this embodiment, the curing agent consists of 15% steel slag, 55% ore slag, 10% primary lithium slag, and 20% secondary lithium slag.

[0080] The activator is a mixture of carbide slag, gypsum, aluminum sulfate and sodium carbonate in a mass ratio of 3:4:0.5:1.

[0081] The composite soil consists of 60% lithium slag, 10% fly ash, and 30% clay.

[0082] Foamed soil is composed of 16% solidifying agent, 70% composite soil, 11% activator and 3% foaming agent.

[0083] The preparation method of foamed soil in this embodiment is as follows:

[0084] Step 1, A: Grind steel slag, mineral slag, primary lithium slag, and secondary lithium slag separately to a specific surface area of ​​500-550 m². 2 / kg (content of particles smaller than 325 mesh ≤1%), mixed evenly according to the ratio to obtain curing agent, transported by tanker to curing agent silo, and then entered into the mixing system through a weighing device.

[0085] B: Mix and grind the carbide slag and gypsum until the specific surface area is 400-450 m². 2 / kg (particles smaller than 325 mesh content ≤5%), mixed evenly with sodium carbonate and aluminum sulfate to obtain activator, which is transported by tanker to activator silo and then enters the mixing system through a weighing device.

[0086] C: The two-stage lithium slag, clay and fly ash are batched on site to obtain composite soil, which is then sent to the mixing system via a belt conveyor. The belt is equipped with a weighing system to control the quality of the composite soil.

[0087] D: Load the foaming agent into the foaming device, prepare foam according to the required amount of foam, and then send the foam into the mixing system.

[0088] Step 2: Steps A, B, C, and D in Step 1 are performed simultaneously. The mixing system uses a twin-shaft mixer + a high-speed activating mixer for two-stage continuous mixing. The first stage mixer speed is 52 r / min and the mixing time is 90 s, while the second stage mixer speed is 460 r / min and the mixing time is 40 s. This helps to promote uniform mixing and stable properties of the foamed soil. After all materials (curing agent + activator + composite soil + foaming agent) are mixed, foamed soil is obtained.

[0089] Example 3

[0090] In this embodiment, the curing agent consists of 10% steel slag, 50% ore slag, 10% primary lithium slag, and 30% secondary lithium slag.

[0091] The activator is a mixture of carbide slag, gypsum, aluminum sulfate and sodium carbonate in a mass ratio of 3:4:0.5:1.

[0092] The composite soil consists of 60% lithium slag, 10% fly ash, and 30% silt.

[0093] Foamed soil is composed of 12% solidifying agent, 73% composite soil, 11% activator and 4% foaming agent.

[0094] The preparation method of foamed soil in this embodiment is as follows:

[0095] Step 1, A: Grind steel slag, mineral slag, primary lithium slag, and secondary lithium slag separately to a specific surface area of ​​500-550 m². 2 / kg (content of particles smaller than 325 mesh ≤1%), mixed evenly according to the ratio to obtain curing agent, transported by tanker to curing agent silo, and then entered into the mixing system through a weighing device.

[0096] B: Mix and grind the carbide slag and gypsum until the specific surface area is 400-450 m². 2 / kg (particles smaller than 325 mesh content ≤5%), mixed evenly with sodium carbonate and aluminum sulfate to obtain activator, which is transported by tanker to activator silo and then enters the mixing system through a weighing device.

[0097] C: The second batch of lithium slag, sludge and fly ash are mixed on site to obtain composite soil, which is then sent to the mixing system via a belt conveyor. The belt is equipped with a weighing system to control the quality of the composite soil.

[0098] D: Load the foaming agent into the foaming device, prepare foam according to the required amount of foam, and then send the foam into the mixing system.

[0099] Step 2: Steps A, B, C, and D in Step 1 are performed simultaneously. The mixing system uses a twin-shaft mixer + a high-speed activating mixer for two-stage continuous mixing. The first stage mixer speed is 52 r / min and the mixing time is 90 s, while the second stage mixer speed is 460 r / min and the mixing time is 40 s. This helps to promote uniform mixing and stable properties of the foamed soil. After all materials (curing agent + activator + composite soil + foaming agent) are mixed, foamed soil is obtained.

[0100] Comparative Example 1

[0101] The only difference from Example 1 is that the second lithium slag in the raw material is calcined and ground, and the calcined and ground lithium slag is used as the raw material; the other raw material types, addition amounts, and process parameters are the same as in Example 1; the specific method for calcining and grinding the original lithium slag is as follows: after calcination at 500℃, it is extremely cooled and ground to a particle size greater than 200 mesh.

[0102] The performance indicators of the foamed soil prepared in Examples 1-3 and Comparative Example 1 were tested. The test methods were carried out in accordance with the "Foamed Concrete" (JGJ266-2011), "Test Method for Performance of Autoclaved Aerated Concrete" (GB / T 11969-2008), and "Technical Specification for Cast-in-place Foamed Lightweight Soil Subgrade of Highway" (DB13-T 5600-2022). The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-volume lithium slag foamed soil, characterized by, The raw materials include a foaming agent 0.5-5% by mass, a curing agent 7-25% by mass, a composite soil 65-85% by mass, and an activator 5-15% by mass; The curing agent includes steel slag 0-20% by mass, slag 30-70% by mass, first-pass lithium slag 0-15% by mass, and second-pass lithium slag 20-50% by mass; The composite soil includes second-pass lithium slag 60-80% by mass, fly ash 10-20% by mass, and soil 0-30% by mass, wherein the content of soil is not 0; The activator is a mixture of carbide slag, gypsum, aluminum sulfate, and sodium carbonate in a mass ratio of (3-4):(4-5):(0-0.5):(0.5-1.5). The first-pass lithium slag is raw first-pass lithium slag, which is a solid waste generated in the process of floating lepidolite, and the main chemical components are Na2O 1-4%, K2O 1-3%, SiO2 50-80%, and Al2O3 7-11%. The second-pass lithium slag is raw second-pass lithium slag, which is a solid waste generated in the process of producing lithium carbonate from lepidolite, and the main chemical components are Na2O 1-4%, K2O 1-3%, SiO2 20-40%, Al2O3 10-15%, MgO 0-2%, CaO 15-25%, and SO3 10-20%. The preparation method of the large-dosage lithium slag foam soil includes the following steps: Step 1, A: Steel slag, slag, first lithium slag and second lithium slag are respectively ground to a specific surface area of 500-550 m 2 / kg and a particle size of less than 325 mesh ≤1%, uniformly mixed in proportion to obtain a solidifying agent, transported to a solidifying agent bin by a tank car, and weighed into a stirring system. B: mix carbide slag and gypsum, grind to specific surface area of 400-450 m 2 / kg and particle content of less than 325 mesh ≤5%, mix with sodium carbonate and aluminum sulfate to obtain an activator, deliver to an activator bin by tank car, and enter the stirring system through a weighing device; C: The second-pass lithium slag, soil, and fly ash are proportioned on site to obtain a composite soil, which is sent into a stirring system through a belt conveying device, and a weighing system is mounted on the belt to control the quality of the composite soil; D: The foaming agent is loaded into a foaming device to prepare foam according to the required amount of foam, and then the foam is sent into the stirring system; Step 2: Steps A, B, C, and D in step 1 are performed synchronously, and a double-shaft stirrer + high-speed activation stirrer two-stage continuous stirring system is used, the stirring speed of the double-shaft stirrer is 52 r / min, the stirring time is 90 s, the stirring speed of the high-speed activation stirrer is 460 r / min, the stirring time is 40 s, and the curing agent + activator + composite soil + foam are stirred to obtain the foam soil.

2. The soil of claim 1, wherein the soil is a soil of a large amount of lithium slag foam soil. The foaming agent is a mixture of water, fatty alcohol polyoxyethylene ether sodium sulfate, sodium dodecyl sulfate, sludge protein, and nano calcium carbonate in a mass ratio of (8-10):(3.5-5):(3.5-5):(3-4):(0.05-0.2).

3. The soil of claim 2, wherein the soil is a soil of a large amount of lithium slag foam soil. The sludge protein contains 25-35% of protein and has a pH value of 11.5-13.

5.

4. The soil of claim 1, wherein the soil is a soil of a large amount of lithium slag foam soil. The soil is at least one of sandy soil, silt, silt, clay, loess, planting soil, and filling soil.

5. The large-dosage lithium slag foam soil according to any one of claims 1-4 is applied to house building, roadbed, trench backfill, and tunnel engineering.

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