Low-saline-alkali slag engineering soil and preparation method thereof

Abstract

The invention provides low-saline-alkali slag engineering soil and a preparation method thereof. The method comprises the following steps: pumping water-containing alkaline residues into a slurry A stirring device, introducing CO2-containing alkaline residue lime kiln flue gas, and adding a dealkalization auxiliary agent to prepare dealkalized alkaline residue slurry A; meanwhile, in another stirring device B, auxiliary materials and water are mixed, and auxiliary slurry B is obtained; next, pumping the dealkalized alkaline residue slurry A and the auxiliary slurry B into a mixed slurry tank, adding an ionic solubilizer, and further stirring to form mixed slurry; and finally, conveying the mixed slurry to a plate and frame dehydrator, and carrying out filter pressing dehydration treatment to obtain a filter cake, namely the low-alkali low-saline-alkali slag engineering soil. The low-alkali and low-salt-alkali slag engineering soil has excellent early strength and rapid hardening characteristics, meanwhile, the dealkalization and desalination efficiency of the alkali slag is remarkably improved, and a solution is provided for recycling, reduction, harmless treatment and high-value utilization of the alkali slag.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization, specifically relating to a low-alkali and low-salt alkali slag engineering soil and a preparation method for preparing low-alkali and low-salt alkali slag engineering soil by synergistic compounding of dealkali slag slurry and auxiliary slurry. Background Technology

[0002] Alkali residue is an unavoidable solid waste generated during the ammonia-soda process for producing soda ash. It has a fine particle size, typically high moisture content, and contains a large amount of volatile organic compounds, making its recycling and reuse extremely difficult. Currently, filter press technology, as a relatively simple and economical waste treatment method, is widely used for the initial treatment of alkali residue. After filter press, the alkali residue is usually stored in stockpiles. Due to the lack of resource utilization pathways, this waste residue is often disposed of through open-air stockpiling or even on-site burial. Such treatment methods not only exacerbate the negative environmental impact of alkali residue but may also lead to serious ecological risks such as dam failures at slag heaps, soil degradation, and pollution. Although alkali residue gains a certain mechanical strength after filter press treatment, it is still far from meeting the strength requirements of engineering applications. This indicates that relying solely on traditional filter press technology is insufficient to achieve the comprehensive utilization of alkali residue. Therefore, developing feasible, large-scale, efficient, and high-value-added alkali residue resource utilization technologies is particularly urgent and necessary.

[0003] Engineering soil, a common basic building material in civil engineering, possesses excellent homogeneity, impermeability, and controllability, making it widely applicable in road, site, and foundation construction. However, current traditional engineering soils largely rely on excavated earth and ordinary loess, whose development and use often lack scientific management and sustainable planning. If soil resources are not rationally developed and protected, over-exploitation and improper use will disrupt the dynamic balance of the soil, leading to soil degradation, depletion, and even the deterioration of the ecosystem.

[0004] It is worth noting that alkali slag mainly contains substances such as calcium chloride (CaCl2), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium sulfate (CaSO4), and sodium chloride (NaCl), many of which are similar to the framework substances in soil. Therefore, alkali slag has the potential to be used as a substitute material for engineering soil, especially in construction filling projects such as site preparation, foundation, and roadbed, and has certain application prospects.

[0005] Patent application CN 117139348A discloses a method for preparing engineering soil from large-scale alkali slag. However, dilute sulfuric acid has strong oxidizing and corrosive properties, which may pose serious safety hazards during the production process. Furthermore, the acid mist and harmful gases that may be generated during sulfuric acid treatment place higher demands on operator safety and environmental protection. Patent application CN 117534435A discloses a method for preparing all-solid-waste engineering soil by co-processing multiple solid wastes with a large amount of pressure-pressed alkali slag. However, the amount of alkali slag is relatively low, and in practical applications, this method may be insufficient to meet the needs of large-scale alkali slag treatment, especially when the amount of alkali slag to be processed is large, making it difficult to achieve its intended efficiency. Summary of the Invention

[0006] In view of this, this invention addresses the technical problems encountered in the preparation and application of engineering soil materials, such as difficulties in the treatment of alkali slag, low utilization rate, and high environmental protection requirements. It proposes a low-alkali, low-salt alkali slag engineering soil and its preparation method. This method achieves improved performance and meets environmental requirements for alkali slag engineering soil through innovative technologies such as efficient dealkali and desalination treatment of alkali slag slurry, synergistic activation of active activators, and mixing processes. The resulting low-alkali, low-salt alkali slag engineering soil has significant environmental and economic benefits. On the one hand, it effectively removes alkaline substances and salts from alkali slag, avoiding pollution of the environment and soil. On the other hand, the prepared low-alkali, low-salt alkali slag engineering soil material has good mechanical properties and stability, meeting the needs of engineering applications such as road infrastructure construction and foundation treatment. Furthermore, this invention has the advantages of low cost and high efficiency, is suitable for large-scale utilization of alkali slag resources and preparation of engineering soil materials, and has broad application prospects.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing low-salt-alkali slag engineering soil, the steps of which are as follows:

[0009] (1) First, alkali residue and water are mixed in an alkali residue slurry tank at a mass ratio of 1:2 to form a uniform alkali residue slurry. Then, the alkali residue slurry is pumped to the A slurry mixing device.

[0010] (2) The flue gas from the alkali slag lime kiln (flue gas concentration of approximately 20.8 vol.%) was introduced into the A slurry mixing device, and the rotation speed of the A slurry mixing device was adjusted to 200 r / min. Then, the dealkali removal aid was added to the mixing device, and the mixing was continued for 10 minutes to obtain the dealkali slag slurry A.

[0011] (3) In the mixing device B, the auxiliary materials and water are mixed at a mass ratio of 2:1. The mixing speed is set to 50 r / min and the mixture is stirred for 10 minutes to obtain auxiliary slurry B.

[0012] (4) Pump the dealkali residue slurry A and the auxiliary slurry B into the mixing tank respectively, and add an ionic solubilizer to the mixed slurry. Set the stirring speed of the mixing tank to 50 r / min and mix for 5 minutes.

[0013] (5) Finally, the slurry in the mixing tank is pumped to a plate and frame dewatering machine for pressure filtration and dewatering. The plate and frame dewatering machine removes water from the slurry through pressure filtration, dewatering and solidification, and finally obtains filter cake, resulting in low-alkali and low-salt alkali slag engineering soil.

[0014] In the technical solution of this invention: in step (2), the aeration flow rate of the flue gas is 5-11 m³ / h. 3 / min / t 碱渣浆 .

[0015] In the technical solution of the present invention: in step (2), the dealkalization aid is composed of L-arginine and L(+)aminosuccinic acid, with weight parts of 0.01-0.8 parts and 0.01-0.6 parts, respectively.

[0016] In the technical solution of the present invention: in step (3), the auxiliary materials are composed of alkaline oxidation slag powder and aluminum refining slag, with weight parts of 0.01-99.9 parts and 0.01-99.9 parts respectively.

[0017] In the technical solution of the present invention: in step (4), the mixed slurry is composed of dealkali residue slurry A and auxiliary slurry B, with weight parts of 60-99.9 parts and 0.01-40 parts, respectively.

[0018] In the technical solution of the present invention: in step (4), the ionic solubilizer is composed of diethylenetriamine pentamethylphosphonic acid and hydroxyethylidene diphosphonic acid, with weight parts of 0.01-0.3 parts and 0.01-0.2 parts, respectively.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) Through the synergistic effect of carbon dioxide gas and dealkali removal aid, this invention significantly reduces the alkalinity of alkaline slurry. Specifically, carbon dioxide gas plays a key role in this process. By reacting with alkaline substances in the alkaline slurry, it effectively removes and stabilizes the alkaline components in the slurry, significantly reducing the pH value of the slurry, thereby avoiding the negative impact of alkaline substances on the environment and subsequent processes. L-arginine and L(+)aminosuccinic acid play a role in promoting the solid-liquid-gas three-phase reaction in this process, which can accelerate the capture and transformation of alkaline ions, causing them to quickly form insoluble precipitates or stable complexes, thereby achieving complete neutralization of alkaline substances.

[0021] (2) This invention uses alkaline oxidizing slag and aluminum refining slag as auxiliary materials. By regulating the dynamic chemical balance of alkalinity and sulfate ions, the formation of sparingly soluble double salt minerals is successfully regulated, breaking the saturation and equilibrium state of leached ions from the alkaline slag and enhancing the reactivity of the alkaline slag with other materials. Diethylenetriaminepentamethylphosphonic acid and hydroxyethylidene diphosphonic acid play a promoting role in this process. By driving the dissociation and dissolution of alkaline slag polymers and ions, they further promote the hydration and gelation reaction, thereby improving the mechanical properties of alkaline slag engineering soil materials.

[0022] (3) The alkali slag engineering soil prepared by this invention exhibits several significant advantages over traditional treatment methods: First, the material possesses superior mechanical properties and rapid strength growth, ensuring early load-bearing capacity during construction. Second, through innovative dealkali removal and ion control technologies, the alkali and chloride ion content is significantly reduced, meeting the stringent requirements for environmental protection and durability of engineering soil. Simultaneously, the process flow of this invention is highly efficient and suitable for large-scale production, ensuring improved production efficiency and meeting the high standards of material quality, stability, and long-term durability required by actual engineering projects. Therefore, this technology demonstrates significant potential for large-scale promotion and application, providing an innovative solution for the resource utilization and green environmental protection treatment of alkali slag. Attached Figure Description

[0023] Figure 1 For comparison of X-ray diffraction analysis of partial comparative examples and alkaline slurry in the examples;

[0024] Figure 2 X-ray diffraction analysis was performed to compare the alkali slag engineering soil prepared in the partial comparative example with the low-alkali and low-salt alkali slag engineering soil obtained in the example after 28 days of curing.

[0025] Figure 3 for Figure 1 The 2θ in the image is a magnified view of a local area within the range of 17-20°. Detailed Implementation

[0026] To further illustrate the technical means and effects of this invention, the following description, in conjunction with embodiments and accompanying drawings, provides a further explanation of the invention. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.

[0027] Example 1

[0028] (1) First, alkali residue and water are mixed in an alkali residue slurry tank at a mass ratio of 1:2 to form a uniform alkali residue slurry. Then, 1000 kg of alkali residue slurry is pumped to the A slurry mixing device.

[0029] (2) The flue gas from the alkali slag lime kiln (flue gas concentration approximately 20.8 vol.%) was introduced into the A slurry mixing device, and the flue gas aeration flow rate was set to 5 m³ / s. 3 / min / t 碱渣浆 Then, adjust the speed of the A slurry mixing device to 200 r / min. Next, add 0.15 parts by weight of L-arginine and 0.1 parts by weight of L(+)aminosuccinic acid to the A slurry mixing device, and continue stirring for 10 minutes to obtain dealkali residue slurry A.

[0030] (3) In the mixing device B, 70 parts by weight of alkaline oxide slag powder and 30 parts by weight of aluminum refining slag are mixed according to the mass ratio, and 50 parts by weight of water is added. The mixing speed of the mixing device B is set to 50 r / min, and the mixture is stirred for 10 minutes to obtain auxiliary slurry B.

[0031] (4) Pump 70 parts by weight of the dealkali residue slurry A and 30 parts by weight of the auxiliary slurry B into the mixing tank C respectively, and add 0.1 parts by weight of diethylenetriamine pentamethylphosphonic acid and 0.05 parts by weight of hydroxyethylidene diphosphonic acid to the mixing tank C. Set the stirring speed of the mixing tank to 50 r / min and mix for 5 minutes to obtain the mixed slurry.

[0032] (5) Finally, the mixed slurry in the mixing tank C is pumped to a plate and frame dewatering machine for pressure filtration and dewatering. The plate and frame dewatering machine removes water from the slurry through pressure filtration, dewatering and solidification, and finally obtains filter cake, which is low-alkali and low-salt alkali slag engineering soil.

[0033] Example 2

[0034] The raw materials and testing methods used in this embodiment are the same as those in Example 1.

[0035] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 1 in that the flue gas aeration flow rate in the raw materials in step (2) is 7m³ / h. 3 / min / t 碱渣浆 .

[0036] Example 3

[0037] The raw materials and testing methods used in this embodiment are the same as those in Example 1.

[0038] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 1 in that the flue gas aeration flow rate in the raw materials in step (2) is 9 m³ / s. 3 / min / t 碱渣浆 Add 0.3 parts by weight of L-arginine and 0.2 parts by weight of L(+)aminosuccinic acid to the stirring device.

[0039] Example 4

[0040] The raw materials and testing methods used in this embodiment are the same as those in Example 1.

[0041] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 1 in that the flue gas aeration flow rate in the raw materials in step (2) is 11 m³ / s. 3 / min / t 碱渣浆 And add 0.6 parts by weight of L-arginine and 0.4 parts by weight of L(+)aminosuccinic acid to the stirring device.

[0042] Example 5

[0043] The raw materials and testing methods used in this embodiment are the same as those in Example 2.

[0044] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 2 in that 0.8 parts by mass of L-arginine and 0.6 parts by mass of L(+)aminosuccinic acid are added to the stirring device in step (2).

[0045] Example 6

[0046] The raw materials and testing methods used in this embodiment are the same as those in Example 3.

[0047] The step of preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differs from that in embodiment 3 in that 50 parts by mass of alkaline oxidizing slag and 50 parts by mass of aluminum refining slag are mixed according to the mass ratio in step (3).

[0048] Example 7

[0049] The raw materials and testing methods used in this embodiment are the same as those in Example 3.

[0050] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 3 in that, in step (3), 30 parts by mass of alkaline oxidizing slag and 70 parts by mass of aluminum refining slag are mixed according to a mass ratio. In step (4), 90 parts by mass of dealkali slag slurry A and 10 parts by mass of auxiliary slurry B are pumped into the mixing slurry tank respectively.

[0051] Example 8

[0052] The raw materials and testing methods used in this embodiment are the same as those in Example 7.

[0053] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 7 in that, in step (4), 80 parts by mass of dealkali slag slurry A and 20 parts by mass of auxiliary slurry B are pumped into the mixing slurry tank respectively.

[0054] Example 9

[0055] The raw materials and testing methods used in this embodiment are the same as those in Example 6.

[0056] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 6 in that, in step (4), 0.2 parts by mass of diethylenetriamine pentamethylphosphonic acid and 0.15 parts by mass of hydroxyethylidene diphosphonic acid are added to the mixed slurry.

[0057] Example 10

[0058] The raw materials and testing methods used in this embodiment are the same as those in Example 8.

[0059] The steps for preparing low-alkali and low-salt alkali slag engineering soil in this embodiment differ from those in Example 8 in that, in step (4), 0.3 parts by mass of diethylenetriamine pentamethylphosphonic acid and 0.2 parts by mass of hydroxyethylidene diphosphonic acid are added to the mixed slurry.

[0060] Comparative Example 1

[0061] The alkaline slurry is pumped to a plate and frame dewatering machine for pressure filtration and dewatering. The plate and frame dewatering machine removes water from the alkaline slurry through pressure filtration, dewatering, and solidification, ultimately yielding a filter cake, which is then used to produce alkaline slurry engineering soil.

[0062] Comparative Example 2

[0063] (1) First, alkali residue and water are mixed in an alkali residue slurry tank at a mass ratio of 1:2 to form a uniform alkali residue slurry. Then, the alkali residue slurry is pumped to a slurry mixing device.

[0064] (2) The flue gas from the alkali slag lime kiln (flue gas concentration approximately 20.8 vol.%) was introduced into the A slurry mixing device, and the flue gas aeration flow rate was set to 9 m³ / s. 3 / min / t 碱渣浆 Then, adjust the speed of the A slurry stirring device to 200 r / min and continue stirring for 10 minutes to obtain the dealkali residue slurry A.

[0065] (3) The dealkali slurry A is pumped to a plate and frame dewatering machine for pressure filtration and dewatering treatment. The plate and frame dewatering machine removes water from the dealkali slurry A through pressure filtration, dewatering and solidification, and finally obtains filter cake and alkali slag engineering soil.

[0066] Comparative Example 3

[0067] The raw materials and test methods used in this comparative example are the same as those in Comparative Example 2.

[0068] The steps for preparing the alkali slag engineering soil material in this comparative example differ from those in comparative example 2 in that 0.6 parts by mass of L-arginine and 0.4 parts by mass of L(+)aminosuccinic acid are added in step (2).

[0069] Comparative Example 4

[0070] (1) First, alkali residue and water are mixed in an alkali residue slurry tank at a mass ratio of 1:2 to form a uniform alkali residue slurry. Then, the alkali residue slurry is pumped to the A slurry mixing device.

[0071] (2) In the mixing device B, 50 parts by mass of alkaline oxidizing slag and 50 parts by mass of aluminum refining slag are mixed according to the mass ratio, and 50 parts by mass of water is added. The mixing speed is set to 50 r / min and the mixture is stirred for 10 minutes to obtain auxiliary slurry B.

[0072] (3) Pump 70 parts by weight of the dealkali residue slurry A and 30 parts by weight of the auxiliary slurry B into the mixing tank C respectively. Set the stirring speed of the mixing tank C to 50 r / min and mix for 5 minutes to obtain the mixed slurry.

[0073] (4) Finally, the mixed slurry in the mixing tank C is pumped to a plate and frame dewatering machine for pressure filtration and dewatering treatment. The plate and frame dewatering machine removes water from the mixed slurry through pressure filtration, dewatering and solidification, and finally obtains filter cake, which is then used to obtain alkali slag engineering soil.

[0074] Comparative Example 5

[0075] The raw materials and test methods used in this comparative example are the same as those in Comparative Example 4.

[0076] The steps for preparing the alkali slag engineering soil material in this comparative example differ from those in comparative example 4 in that 0.2 parts by mass of diethylenetriamine pentamethylphosphonic acid and 0.15 parts by mass of hydroxyethylidene diphosphonic acid are added in step (3).

[0077] The mineral composition of the low-alkali, low-salt alkali slag engineering soil prepared in some embodiments and the alkali slag engineering soil prepared in the comparative embodiment is as follows: Figure 1 As shown, Comparative Example 1 is an untreated alkali slag slurry. Comparing the XRD patterns of Examples 1, 3, and Comparative Example 1, it can be seen that after treatment with CO2 and dealkali removal aids in the flue gas of the alkali slag lime kiln, the alkaline components such as calcium hydroxide (Ca(OH)2) in the dealkali slag slurry A are significantly reduced, while the contents of carbonate products such as calcium carbonate (CaCO3) and sodium carbonate (Na2CO3) are significantly increased, indicating a significant dealkali removal effect. Figure 2 and Figure 3The mineral composition of low-alkali, low-salt alkali slag engineering soil prepared in some embodiments and alkali slag engineering soil prepared in the comparative example after 28 days of curing is shown. Comparative analysis revealed that the contents of Ca(OH)₂ and magnesium hydroxide (Mg(OH)₂) were significantly reduced in the low-alkali, low-salt alkali slag engineering soil. This was mainly attributed to two factors: firstly, Ca(OH)₂ underwent a pozzolanic reaction under the action of the pozzolanic active material; secondly, Mg(OH)₂ reacted with auxiliary materials under low pH conditions to form MSH gel. Furthermore, this reaction was further promoted with increasing ionic solubilizer dosage. Notably, the ionic solubilizer also effectively accelerated the dissolution-recrystallization process of gypsum in the alkali slag, thereby significantly increasing the content of the hydration product ettringite (AFt) in the system, further optimizing the mineral structure and properties of the engineering soil.

[0078] The pH test results of the low-alkali and low-salt alkali slag engineering soils prepared in each embodiment and the alkali slag engineering soils prepared in the comparative examples are shown in Table 1. The test results show that the pH value of the alkali slag engineering soil without dealkali treatment is 11.65, mainly due to the presence of a large amount of alkaline components in the alkali slag, such as Ca(OH)2. However, excessively high pH values ​​significantly reduce the environmental adaptability of alkali slag engineering soils in applications, limiting their widespread use in soil remediation and engineering filler fields. As can be seen from the test data of Comparative Example 2, the pH value of the alkali slag engineering soil decreased significantly after dealkali treatment with CO2 from the flue gas of the alkali slag lime kiln. The results of Comparative Example 3 further indicate that, based on CO2 dealkali treatment, the addition of a dealkali treatment aid further reduces the pH value. Specifically, the data from Examples 2 to 5 show that, through the synergistic effect of CO2 and the dealkali treatment aid, the pH value of the low-alkali and low-salt alkali slag engineering soil was successfully reduced to below 9.5, meeting the pH requirements for engineering soil applications.

[0079] Table 1 pH of soil in alkaline slag engineering projects

[0080]

[0081] Table 2 shows the mechanical property test results of the low-alkali and low-salt alkali slag engineering soils prepared in each example and the alkali slag engineering soils prepared in the comparative examples. The mechanical properties of the alkali slag engineering soils depend on the dense structure after filtration and the subsequent hydration reaction. Comparative Example 1 (untreated conventional alkali slag engineering soil) only reached 0.21 MPa in the 3-day unconfined compressive strength test and only 0.30 MPa at 28 days, showing low strength and density. The tests of Comparative Examples 2 and 3 show that the single alkali slag dealkali treatment has a limited effect on improving the unconfined compressive strength. Although the calcium carbonate generated during the dealkali process can fill the structural voids and improve the initial density of the alkali slag after filtration, its contribution to the hydration reaction is small. As can be seen from Comparative Examples 4 and 5, the addition of auxiliary materials or ionic solubilizers alone only slightly improves the compressive strength of the alkali slag engineering soils. In contrast, the test results of Examples 1-10 demonstrate that the synergistic effect of alkali slag dealkali treatment with auxiliary materials and ionic solubilizers can significantly improve the unconfined compressive strength of the low-alkali and low-salt alkali slag engineering soils. In this combination, the auxiliary materials react with the alkaline slag under low pH conditions to generate highly polymerized, high-strength active products, significantly enhancing the mechanical properties of the material. Furthermore, these products exhibit high chemical stability under low pH conditions, ensuring the durability and structural stability of the engineering soil in long-term applications. Ion solubilizers further enhance the mechanical properties in the system, with mechanisms including optimizing the concentrations of active aluminum and calcium ions, balancing sulfate ion dynamics in the solution, and regulating the pH value of the solution. Simultaneously, the ion solubilizers effectively control the dissolution-recrystallization process of gypsum in the alkaline slag, promoting a tighter packing and bonding relationship between the alkaline slag and auxiliary materials, improving the density and overall mechanical properties of the material. It is important to note that there is a certain balance between compressive strength and the degree of dealkali treatment. If the degree of dealkali treatment is too high, the potential active components in the alkaline slag may prematurely transform into stable components, reducing the reactive substances available for reaction in the system and weakening the final mechanical strength. Therefore, rationally controlling the degree of dealkali treatment is crucial to ensuring the excellent performance of the engineering soil.

[0082] Table 2 Mechanical properties (MPa) of soil used in alkali slag engineering projects

[0083]

[0084] Table 3 shows the test results of chloride ion content in the low-alkali and low-salt alkali slag engineering soil prepared in each embodiment and the alkali slag engineering soil prepared in the comparative examples. The chloride ion content in the alkali slag engineering soil is directly affected by the degree of alkali removal and the density of the material. In Comparative Example 1, the chloride ion content of the untreated alkali slag engineering soil was relatively high, reaching approximately 40038.4 mg / L. The results of Comparative Examples 2 and 3 show that after treatment with CO2 and alkali removal agents, the chloride ion content decreased significantly, falling below 20000 mg / L. This indicates that the alkali removal treatment has a significant effect on chloride ion removal. Comparative Examples 4 and 5 further tested the effect of adding only auxiliary materials, and the results showed that its effect on chloride ion content was limited and failed to significantly reduce chloride ion leaching. In contrast, the tests of Examples 1-10 show that by adding auxiliary materials and ion solubilizers simultaneously with alkali slag dealkali treatment, the chloride ion content can be significantly reduced, thus reducing the risk of chloride ion leaching in the alkali slag engineering soil. Specifically, Example 10 showed the highest chloride ion solidification rate, exceeding 90%, significantly improving the chloride ion solidification effect of the alkali slag engineering soil.

[0085] Table 3 Chloride leaching content (mg / L) of soil from alkaline slag engineering projects

[0086]

[0087] The method for preparing low-alkali and low-salt alkali slag engineering soil provided by this invention enables the large-scale application of alkali slag, while ensuring that the resulting engineering soil material exhibits excellent performance in terms of mechanical properties and alkali ion and chloride ion leaching control, meeting the stringent requirements of practical engineering applications.

[0088] Finally, the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing low-salt-alkali slag engineering soil, characterized in that, The method includes the following steps: (1) Mix the alkali residue with water at a mass ratio of 1:2 to form a uniform alkali residue slurry, and pump the alkali residue slurry into the A slurry mixing device; (2) The flue gas from the alkali slag lime kiln is introduced into the flue gas absorption tank, and a dealkali-removing aid is added to the stirring device to obtain dealkali slag slurry A. (3) In the mixing device B, the auxiliary materials and water are mixed at a mass ratio of 2:1 and stirred to obtain auxiliary slurry B; (4) Pump the dealkali residue slurry A and the auxiliary slurry B into the mixing tank C respectively, and add an ion solubilizer to the mixing tank C to obtain a mixed slurry; (5) The mixed slurry in the mixing tank C is pumped to the plate and frame dewatering machine for pressure filtration, dewatering and solidification. The resulting filter cake is the low-alkali and low-salt alkali slag engineering soil.

2. The method for preparing low-alkali and low-salt alkali slag engineering soil according to claim 1, characterized in that, In step (2), the flue gas aeration flow rate is 5-11 m³ / h. 3 / min / t 碱渣浆 .

3. The method for preparing low-alkali and low-salt alkali slag engineering soil according to claim 2, characterized in that, In step (2), the dealkalization aid is composed of 0.01-0.8 parts by weight of L-arginine and 0.01-0.6 parts by weight of L(+)aminosuccinic acid.

4. The method for preparing low-alkali and low-salt alkali slag engineering soil according to claim 3, characterized in that, In step (3), the auxiliary materials consist of 0.01-99.9 parts by weight of alkaline oxidizing slag powder and 0.01-99.9 parts by weight of aluminum refining slag.

5. The method for preparing low-alkali and low-salt alkali slag engineering soil according to claim 4, characterized in that, In step (4), 60-99.9 parts by weight of the dealkali residue slurry A and 0.01-40 parts by weight of the auxiliary slurry B are pumped into the mixing tank C respectively.

6. The method for preparing low-alkali and low-salt alkali slag engineering soil according to claim 5, characterized in that, In step (4), the ionic solubilizer is composed of 0.01-0.3 parts by mass of diethylenetriamine pentamethylphosphonic acid and 0.01-0.2 parts by mass of hydroxyethylidene diphosphonic acid.

7. A low-salt, alkaline slag engineering soil, characterized in that: The low-alkali and low-salt alkali slag engineering soil is prepared by the preparation method of the low-alkali and low-salt alkali slag engineering soil according to any one of claims 1 to 6.

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