Iron slag ash and waste soil composite curing agent as well as preparation method and application thereof

Abstract

The invention relates to the field of resource recycling, and discloses an iron slag ash and waste soil composite curing agent as well as a preparation method and application thereof. The composite curing agent comprises the following components in parts by weight: 30-50 parts of iron slag ash; 20 to 40 parts of waste soil; 10-20 parts of industrial alkaline residues; 5-10 parts of a functional auxiliary agent; 3-5 parts of a curing synergist; the curing synergist is composed of an inner core and a coating layer, the inner core material comprises a porous carrier and an exciting agent, and the film forming material of the coating layer is one or more of stearic acid, paraffin and polyethylene wax; the weight ratio of the core material to the coating layer material is (8-9): 1. According to the composite curing agent, resource utilization of waste is achieved, the material cost is remarkably reduced, and the composite curing agent is particularly suitable for flow-state backfilling, light filling and sludge in-situ curing and has remarkable environmental protection and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of resource recycling, more particularly, it relates to a composite solidifying agent for iron slag ash abandoned soil and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of infrastructure construction in China, a large amount of abandoned soil is generated in road subgrade, dam filling and other engineering projects. At the same time, a large amount of industrial solid waste, such as iron slag ash, alkali residue and the like, is generated in the heavy industry field every year. The above-mentioned waste is currently mainly treated by open-air stacking or landfill, which not only occupies valuable land resources, but also poses a serious threat to the soil, water and atmospheric environment due to dust, heavy metals and alkaline substances. In addition, traditional soil solidification mainly uses cement, lime and other traditional cementitious materials. Although these materials are effective, they have high energy consumption and large carbon emissions in the production process, resulting in high engineering cost and heavy environmental burden. Therefore, it has become an important research direction in the field of civil engineering materials and environmental protection to recycle the above-mentioned waste and replace traditional cementitious materials such as cement and lime.

[0003] At present, there are some schemes for preparing soil solidifying agents from solid waste in the prior art, such as using single or composite materials such as slag, fly ash, steel slag and the like. However, such solidifying agents are difficult to achieve ideal results.

[0004] Therefore, it is an urgent problem to be solved in the field to develop a new type of composite solidifying agent to solve the problems of waste utilization and efficient solidification. SUMMARY

[0005] The present application aims to overcome the deficiencies in the prior art and provide a composite solidifying agent for iron slag ash abandoned soil which can solve the problems of waste utilization and efficient solidification.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: In a first aspect, the present application provides a composite solidifying agent for iron slag ash abandoned soil, The composite solidifying agent for iron slag ash abandoned soil provided by the present application comprises the following components by weight: 30-50 parts of iron slag ash; 20-40 parts of abandoned soil; 10-20 parts of industrial alkali residue; 5-10 parts of functional adjuvant; 3-5 parts of solidification synergist; The solidification synergist is composed of a core and a coating layer, the core material includes a porous carrier and an exciter, the film-forming material of the coating layer is one or more of stearic acid, paraffin and polyethylene wax; the weight ratio of the core material and the coating layer material is (8-9):1.

[0007] Further, the preparation method of the solidification synergist is: Step 1, add the porous carrier to the saturated solution of the exciter, immerse at 60-80℃ for 2-4 hours; Step 2, filter the immersed mixture and dry at 105±5℃ to constant weight to obtain a powder intermediate; Step 3, heat the film-forming material of the coating layer to a molten liquid, slowly add the powder intermediate to the molten film-forming material, maintain the temperature and continue to stir, so that the surface of the powder intermediate is uniformly coated with the liquid film-forming material; Step 4, cool the coated mixture to room temperature, re-solidify the film-forming material, cool, crush and sieve to obtain the solidification synergist.

[0008] Further, the porous carrier is one or more of diatomite, attapulgite and molecular sieve.

[0009] Further, the exciter is one or more of sodium sulfate, sodium silicate, sodium carbonate and calcium chloride.

[0010] Further, the weight ratio of the core material and the coating layer material is 8.5:1.

[0011] Further, the functional adjuvant includes a foam stabilizer, a pH regulator and an interface modifier.

[0012] Further, the foam stabilizer is one or more of sodium stearate, sodium dodecyl sulfate and rosin gum thermal polymer; The interface modifier is one or more of γ-aminopropyl triethoxysilane, γ-(2,3-epoxypropoxy) propyl trimethoxysilane, vinyl triethoxysilane and methacryloyloxy propyl trimethoxysilane.

[0013] Further, in the functional adjuvant, the weight ratio of the foam stabilizer, the pH regulator and the interface modifier is foam stabilizer:pH regulator:interface modifier 1:(2-3):(0.5-1).

[0014] In a second aspect, the application provides a preparation method of the iron slag ash waste soil composite solidification agent, including the following steps: Step 1, pretreatment of iron slag ash, the iron slag ash is dried at a temperature of 105±5℃ until its water content is reduced to below 1%, crushed, sieved to a particle size of <5mm, and magnetically separated to remove mixed metal iron scraps therein; Step 2, pretreatment of waste soil, the waste soil is naturally aired to reduce the water content to below 5%, crushed, and sieved to a particle size of <5mm; Step 3, pretreatment of industrial alkali residue, the industrial alkali residue is mechanically dewatered by a filter press to reduce the water content to below 30%, formed into a filter cake, broken to <50mm, dried to reduce the water content to below 3%, crushed, and sieved to 60 mesh; Step 4, first-stage dry mixing of the pretreated iron slag ash, waste soil and industrial alkali residue, addition of functional additives and solidification synergists, and then second-stage dry mixing to obtain a dry mixture; Step 5, wet ball milling to control the particle size D90≤45μm, and then aging and curing at a temperature of 50~70℃ for 24~48 hours to obtain the composite solidifying agent.

[0015] In a third aspect, the application provides application of the iron slag ash and waste soil composite solidifying agent in building foundation backfilling, roadbed light filling and silt in-situ solidification.

[0016] In summary, the application has the following beneficial effects: 1. The raw materials of the composite solidifying agent of the application are all industrial waste and waste soil, realizing resource utilization of waste and significantly reducing material cost; 2. The application prepares a flowable solidified soil with high compressive strength and low bulk density through the synergistic effect of iron slag ash, industrial alkali residue and functional additives, and introduction of waste soil; 3. The preparation method of the application adopts the process of waste material crushing, dry mixing activation, wet ball milling and aging modification, the preliminary activation of the material surface is realized by the dry mixing activation, the specific surface area of the material is greatly improved by the subsequent wet ball milling, the subsequent alkali activation reaction is more sufficient, and the stable formation of the product phase is ensured in the aging process, thereby greatly improving the mechanical properties. DETAILED DESCRIPTION

[0017] The technical solutions and effects of the application are further described in detail below. It can be understood that the specific embodiments described herein are only used to explain the application, and not to limit the application.

[0018] Example 1 The embodiment discloses an iron slag ash and waste soil composite solidifying agent, which comprises the following components in parts by weight: iron slag ash 30 parts; waste soil 20 parts; industrial alkali residue 10 parts; functional additives 5 parts; and solidification synergists 3 parts.

[0019] The curing synergist consists of a core and a coating layer. The core material includes a porous carrier and an activator, and the film-forming material of the coating layer is polyethylene wax. The weight ratio of the core material to the coating layer material is 8:1.

[0020] The preparation method of this curing enhancer is as follows: Step 1: Add the porous support to a saturated solution of the activator and immerse it at a constant temperature of 70°C for 3 hours; Step 2: Filter and separate the impregnated mixture, and dry it at 105±5℃ to constant weight to obtain a powder intermediate; Step 3: Heat the coating film-forming material to a molten liquid, slowly add the powder intermediate to the molten film-forming material, maintain the temperature and continue stirring, so that the surface of the powder intermediate is uniformly coated by the liquid film-forming material. Step 4: Cool the coated mixture to room temperature, allow the film-forming material to re-solidify, cool, crush, and sieve to obtain the curing synergist.

[0021] The porous carrier is diatomaceous earth.

[0022] The activator is sodium sulfate.

[0023] Functional additives include foam stabilizers, pH adjusters, and interface modifiers. The ratio of foam stabilizer to pH adjuster to interface modifier is 1:2:0.5 by weight.

[0024] The foam stabilizer is sodium stearate.

[0025] The pH adjuster is quicklime.

[0026] The interface modifier is γ-aminopropyltriethoxysilane.

[0027] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0028] Example 2 This embodiment discloses a composite curing agent for iron slag ash and waste soil, which differs from Embodiment 1 in that it includes the following components in parts by weight: 40 parts iron slag ash; 30 parts waste soil; 15 parts industrial alkali slag; 7 parts functional additives; and 4 parts curing synergist.

[0029] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0030] Example 3 This embodiment discloses a composite curing agent for iron slag ash and waste soil, which differs from Embodiment 1 in that it includes the following components in parts by weight: 50 parts iron slag ash; 40 parts waste soil; 20 parts industrial alkali slag; 10 parts functional additives; and 5 parts curing synergist.

[0031] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0032] Example 4 This embodiment discloses a composite curing agent for waste soil and slag ash. The difference from Embodiment 1 is that the curing synergist is composed of a core and a coating layer. The core material includes a porous carrier and an activator, and the film-forming material of the coating layer is polyethylene wax. The weight ratio of the core material to the coating layer material is 8.5:1.

[0033] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0034] Example 5 This embodiment discloses a composite curing agent for waste soil and slag ash. The difference from Embodiment 1 is that the curing synergist is composed of a core and a coating layer. The core material includes a porous carrier and an activator. The film-forming material of the coating layer is one or more of stearic acid, paraffin wax and polyethylene wax. The weight ratio of the core material to the coating layer material is 9:1.

[0035] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0036] Example 6 This embodiment discloses a composite solidifying agent for waste soil and slag ash. The difference from Embodiment 1 is that the functional additives include a foam stabilizer, a pH adjuster, and an interface modifier. The weight ratio of the foam stabilizer: pH adjuster: interface modifier is 1:3:1.

[0037] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0038] Comparative Example 1 This embodiment discloses a composite curing agent for iron slag ash and waste soil, which differs from Embodiment 1 in that it includes the following components in parts by weight: 30 parts iron slag ash; 20 parts waste soil; 10 parts industrial alkali slag; and 8 parts functional additives.

[0039] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives are added, and then a second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0040] Comparative Example 2 This embodiment discloses a composite curing agent for waste soil and slag ash. The difference from Embodiment 1 is that the curing synergist is composed of a core and a coating layer. The core material includes a porous carrier and an activator, and the film-forming material of the coating layer is polyethylene wax. The weight ratio of the core material to the coating layer material is 6:1.

[0041] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0042] Comparative Example 3 This embodiment discloses a composite curing agent for waste soil and iron slag ash, which differs from Embodiment 1 in that it includes the following components in parts by weight: 70 parts iron slag ash; 10 parts industrial alkali slag; 5 parts functional additives; and 3 parts curing enhancer.

[0043] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 3: The pretreated iron slag ash and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain the dry-mix material. Step 4: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0044] Comparative Example 4 This embodiment discloses a composite curing agent for waste soil and iron slag ash, which differs from Embodiment 1 in that it includes the following components in parts by weight: 50 parts waste soil; 30 parts industrial alkali slag; 5 parts functional additives; and 3 parts curing enhancer.

[0045] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 2, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 3: The pretreated waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 4: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0046] Comparative Example 5 This embodiment discloses a composite curing agent for iron slag ash and waste soil, which differs from Embodiment 1 in that it includes the following components in parts by weight: 50 parts iron slag ash; 30 parts waste soil; 5 parts functional additives; and 3 parts curing enhancer.

[0047] The preparation method of this composite solidifying agent for waste soil and slag includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3: The pretreated iron slag ash and waste soil are first-stage dry-mixed, functional additives and curing synergists are added, and then a second-stage dry-mixing is carried out to obtain the dry-mix material. Step 4: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 60℃ for 48 hours to obtain the composite curing agent.

[0048] Performance testing 1. Sample preparation for testing: The composite curing agents prepared in each embodiment and comparative example were used at 150 kg / m³. 3 The appropriate amount of additive was mixed with standard sand and water to prepare fluidized solidified soil test blocks. The water-to-solid ratio was 0.45. After stirring, the blocks were poured into triple molds measuring 40mm × 40mm × 160mm and cured under standard conditions (temperature 20±1°C, humidity ≥95%) until the specified age before testing.

[0049] 2. Test Items and Methods: Flowability: Referring to "GB / T 50448-2015 Technical Specification for Application of Cement-based Grouting Materials", the initial flowability of freshly mixed grout was tested using a flowability test mold (truncated cone mold), with the unit being mm.

[0050] Wet density: Pour freshly mixed slurry into a graduated cylinder of known volume, weigh it, and calculate the weight per unit volume, in g / cm³. 3 .

[0051] Compressive strength: Refer to GB / T 17671-2021 Cement mortar strength test method (ISO method) to test the compressive strength of the test blocks after curing for 7 days and 28 days, in MPa.

[0052] Water immersion strength retention rate: The test block after 28 days of curing was immersed in water for 7 days. After being taken out and dried, its compressive strength was tested and the retention rate (%) was calculated by comparing it with the strength after standard curing for 28 days.

[0053] 3. Test Results: As can be seen from the data in Table 1, the composite curing agents prepared in Examples 1-6 of this invention all exhibit excellent comprehensive performance.

[0054] First, the flowability of the freshly mixed grout in all examples was greater than 225 mm, meeting the construction requirements for fluidized bed filling. The wet bulk density of the composite curing agents prepared in Examples 1-6 was all below 1.55 g / cm³. 3 It can effectively reduce the foundation load when used for backfilling.

[0055] Secondly, while making extensive use of solid waste, this invention still provides high mechanical strength, with a maximum 28-day compressive strength of 4.2 MPa and a minimum of 3.0 MPa, meeting the strength requirements of projects such as building foundation pit backfilling and roadbed subgrade.

[0056] Furthermore, the water immersion strength retention rate of all embodiments exceeded 92%, indicating that the hydration products have a stable structure, excellent water resistance, and can maintain strength for a long time in a humid underground environment without easily softening.

[0057] Finally, by comparing with Comparative Example 1, it can be seen that without the synergist, the 7-day and 28-day strengths both decreased significantly, and the water resistance deteriorated. This proves that the curing synergist can continuously activate its activity and significantly improve the later-stage strength and durability.

[0058] By comparing with Comparative Example 2, it can be seen that when there is too much coating material, it will hinder the release of internal activators, resulting in slow early strength development. At the same time, excessive organic matter may also have a negative impact on strength. The optimal ratio of core to coating is (8~9):1.

[0059] Comparisons of Examples 3, 4, and 5 show that iron slag ash, waste soil, and industrial alkali slag are all indispensable. The absence of any one of these core components leads to incomplete system reactions, significant deterioration in strength, or an increase in bulk density, demonstrating the rationality of the formulation system of this invention and the synergistic effect among the components.

[0060] In summary, this invention, through the scientific proportioning of various raw materials and the use of curing synergists, successfully prepared a novel composite curing agent with good workability, high strength, water resistance, and durability. This enables the high-value-added resource utilization of industrial waste and waste soil, achieving significant environmental benefits while reducing engineering costs.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A composite solidifying agent for iron slag ash waste soil, characterized in that, The components include the following parts by weight: 30-50 parts of iron slag ash; 20-40 portions of waste soil; 10-20 parts of industrial alkali residue; 5-10 parts of functional additives; 3-5 parts of curing synergist; The curing synergist consists of a core and a coating layer. The core material includes a porous carrier and an activator. The film-forming material of the coating layer is one or more of stearic acid, paraffin wax, and polyethylene wax. The weight ratio of the core material to the coating layer material is (8~9):

1.

2. The composite solidifying agent for iron slag ash and waste soil according to claim 1, characterized in that, The preparation method of the curing synergist is as follows: Step 1: Add the porous support to a saturated solution of the activator and immerse it at a constant temperature of 60-80°C for 2-4 hours; Step 2: Filter and separate the impregnated mixture, and dry it at 105±5℃ to constant weight to obtain a powder intermediate; Step 3: Heat the coating film-forming material to a molten liquid, slowly add the powder intermediate to the molten film-forming material, maintain the temperature and continue stirring, so that the surface of the powder intermediate is uniformly coated by the liquid film-forming material. Step 4: Cool the coated mixture to room temperature, allow the film-forming material to re-solidify, cool, crush, and sieve to obtain the curing synergist.

3. The composite solidifying agent for iron slag ash and waste soil according to claim 2, characterized in that, The porous carrier is one or more of diatomaceous earth, attapulgite, and molecular sieve.

4. The composite solidifying agent for iron slag ash and waste soil according to claim 2, characterized in that, The activator is one or more of sodium sulfate, sodium silicate, sodium carbonate, and calcium chloride.

5. The composite solidifying agent for iron slag ash and waste soil according to claim 2, characterized in that, The weight ratio of the core material to the coating material is 8.5:

1.

6. The composite solidifying agent for iron slag ash and waste soil according to claim 1, characterized in that, The functional additives include foam stabilizers, pH adjusters, and interface modifiers.

7. The composite solidifying agent for iron slag ash and waste soil according to claim 6, characterized in that, The foam stabilizer is one or more of sodium stearate, sodium dodecyl sulfate, and rosin thermopolymer; The interface modifier is one or more of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltriethoxysilane, and methacryloyloxypropyltrimethoxysilane.

8. The composite solidifying agent for iron slag ash and waste soil according to claim 6, characterized in that, In the functional additives, the foam stabilizer, pH adjuster and interface modifier are calculated by weight ratio as follows: foam stabilizer: pH adjuster: interface modifier = 1:(2~3):(0.5~1).

9. The preparation method of the composite solidifying agent for iron slag ash waste soil according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1, Pretreatment of iron slag ash: Dry the iron slag ash at 105±5℃ until its moisture content drops to below 1%, crush it, sieve it to a particle size of <5mm, and perform magnetic separation to remove the mixed iron filings. Step 2, Pre-treatment of waste soil: The waste soil is naturally dried to reduce the moisture content to below 5%, crushed, and sieved to a particle size of <5mm. Step 3, Pretreatment of industrial alkali residue: Mechanical dewatering using a filter press to reduce the moisture content to below 30%, forming a filter cake, crushing to <50mm, drying to reduce the moisture content to below 3%, pulverizing, and sieving to 60 mesh; Step 4: The pretreated iron slag ash, waste soil and industrial alkali slag are first-stage dry-mixed, functional additives and curing enhancers are added, and then the second-stage dry-mixing is carried out to obtain dry-mixed material. Step 5: Wet ball milling, controlling the output particle size D90≤45μm, followed by aging and curing at 50~70℃ for 24~48 hours to obtain the composite curing agent.

10. The application of the composite solidifying agent for waste soil and iron slag ash as described in any one of claims 1-8 in backfilling of building foundation pits, lightweight filling of roadbeds, and in-situ solidification of silt.

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