Slow-release type anti-freezing aggregate based on steel slag modification and preparation method of slow-release type anti-freezing aggregate

Abstract

The invention relates to a slow-release anti-freezing aggregate based on steel slag modification and a preparation method thereof.The modified steel slag anti-freezing aggregate takes steel slag as a matrix, the content of free calcium oxide in the modified steel slag anti-freezing aggregate is lower than 2.0%, and an anti-freezing agent is loaded in a microporous structure of the modified steel slag anti-freezing aggregate; the aggregate is prepared from the following components in parts by mass: 90-100 parts of steel slag particles; 15-30 parts of an anti-freezing agent; 0.2 to 2 parts of a reaction accelerator; and 1-3 parts of a post-treatment agent. The method has the beneficial effects that the anti-freezing agent solution and the steel slag f-CaO are subjected to directional chemical reaction under the heating condition, so that the hidden danger of volume expansion is fundamentally eliminated, and meanwhile, high-capacity adsorption and crystallization storage of the anti-freezing agent are realized by virtue of inherent pores of the steel slag; the composite membrane formed in the post-treatment stage realizes slow and lasting release of the anti-freezing agent in an ice and snow environment by regulating and controlling the water permeation rate.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, and in particular relates to a slow-release anti-icing aggregate based on steel slag modification and its preparation method. Background Technology

[0002] In high-altitude and cold regions, road icing is a frequent problem during the snowy season, becoming a key bottleneck affecting traffic operation and road lifespan. Road icing directly leads to a significant reduction in the road surface's skid resistance coefficient, seriously threatening driving safety and significantly reducing traffic efficiency. It also causes structural damage to concrete, such as frost heave, potholes, and cracks, thus drastically shortening the service life of concrete roads. Currently, the mainstream anti-icing solution in the industry is to apply anti-icing agents to the surface for external de-icing. However, this method has obvious limitations: the anti-icing cycle is short, the operation efficiency is low, and long-term use can corrode the road surface structure and adversely affect the surrounding soil, water bodies, and other ecological environments, making it difficult to meet the requirements for long-term and environmentally friendly anti-icing solutions.

[0003] Meanwhile, the steel industry faces the challenge of disposing of massive amounts of steel slag. my country's steel industry generates over 100 million tons of steel slag annually, but its comprehensive utilization rate is less than 30%. The core limiting factor is the 3%-8% free calcium oxide content in the slag. This component reacts with water to form calcium hydroxide, accompanied by a 98% volume expansion, causing severe cracking in building materials and rendering the slag unusable. Existing steel slag stabilization technologies have significant drawbacks: natural aging requires open-air storage for over six months, with land costs alone reaching 120-200 yuan / ton; steam curing processes have energy costs exceeding 80 yuan / ton, making them uneconomical; carbonation treatment is inefficient, requiring over 60 hours per treatment due to slow CO2 permeation rates; and acid treatment generates highly polluting wastewater, adding an extra 35-50 yuan / ton in wastewater treatment costs. These technological bottlenecks directly limit the large-scale application of steel slag in road materials and other fields, leading to the long-term accumulation of large amounts of steel slag, occupying land resources and creating environmental pressure.

[0004] In summary, the hazards of road icing in high-altitude and cold regions and the difficulties in the large-scale resource utilization of steel slag urgently need to be addressed simultaneously. Therefore, there is an urgent need to develop a slow-release anti-icing aggregate material based on steel slag modification. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a slow-release anti-icing aggregate based on steel slag modification and its preparation method.

[0006] In a first aspect, a modified steel slag anti-icing aggregate is provided. The modified steel slag anti-icing aggregate uses steel slag as a matrix, has a low free calcium oxide content, and its microporous structure is loaded with an anti-icing agent. By mass, the aggregate is made of the following components: 90-100 parts of steel slag particles; 15-30 parts of anti-icing agent; 0.2-2 parts of reaction promoter; and 1-3 parts of post-treatment agent.

[0007] Preferably, the steel slag particles have a particle size of 3-10 mm and the CaO content in the steel slag is greater than 50%.

[0008] Preferably, the anti-icing agent is selected from at least one of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate.

[0009] Preferably, the reaction promoter is selected from at least one of acetic acid, citric acid, and ammonium chloride.

[0010] Preferably, the post-treatment agent includes a silane coupling agent and a waterproof dispersion; the silane coupling agent is selected from one of KH550, KH560 or KH570; the waterproof dispersion is selected from at least one of ethylene-vinyl acetate copolymer, acrylate, polyurethane or silicone resin.

[0011] The second aspect provides a method for preparing modified steel slag anti-icing aggregate as described in the first aspect, comprising:

[0012] Step 1: Crush and screen the steel slag to obtain steel slag particles with a particle size of 3-10 mm, and then perform magnetic separation to remove impurities;

[0013] Step 2: Dissolve the anti-icing agent and reaction accelerator in water to prepare a solution with a mass concentration of 10% to 30%;

[0014] Step 3: Immerse the steel slag particles obtained in Step 1 into the solution obtained in Step 2, control the liquid-solid mass ratio to be 1:1 to 2:1, and stir the mixture at a constant temperature of 60 to 95°C for 12 to 24 hours.

[0015] Step 4: Separate the reaction materials into solid and liquid phases, and dry the resulting solid particles at 40-60°C to constant weight;

[0016] Step 5: Heat the dried solid particles to 50-80℃ and keep them at that temperature. Then, spray the post-treatment agent evenly onto the surface of the hot solid particles to obtain modified steel slag anti-icing aggregate.

[0017] Preferably, in step 2, the anti-icing agent is selected from at least one of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate.

[0018] Preferably, in step 2, the reaction promoter is selected from at least one of acetic acid, citric acid, and ammonium chloride, and the amount added is 0.2 to 2 parts based on the mass of the steel slag particles.

[0019] Preferably, step 4, after solid-liquid separation, also includes a residual liquid recycling process: lime milk is added to the separated residual liquid to adjust the pH to 8-10, polyaluminum chloride or polyacrylamide flocculant is added to precipitate heavy metal ions, and the resulting supernatant is reused for solution preparation in step 2.

[0020] Preferably, in step 5, the mass ratio of silane coupling agent to waterproof dispersion in the post-treatment agent is 1:2 to 1:4; the silane coupling agent is selected from one of KH570, KH560, and KH550; and the waterproof dispersion is selected from at least one of ethylene-vinyl acetate copolymer, acrylate, polyurethane, and silicone resin.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention utilizes the directional chemical reaction between the anti-icing agent solution and steel slag f-CaO under heating conditions to fundamentally eliminate the risk of volume expansion. At the same time, it utilizes the inherent pores of steel slag to achieve high-capacity adsorption and crystallization storage of the anti-icing agent. The composite membrane formed in the post-treatment stage controls the water permeation rate to achieve slow and sustained release of the anti-icing agent in the snow and ice environment. Its release cycle can be more than 3 times that of the traditional spreading method.

[0023] 2. This invention achieves a solid waste utilization rate exceeding 90% and an f-CaO conversion rate >85% through a steel slag modification process, completely eliminating the potential risk of steel slag volume expansion. The simultaneously constructed microporous reservoir and hydrophobic controlled-release membrane work synergistically to maintain the particles' long-term ice-melting function even at -10℃, and significantly reduce the risk of soil salinization through an acetate system. The resulting particles have a compressive strength ≥25MPa, and when used as road aggregate, they can improve the asphalt-aggregate interfacial adhesion by 20%, providing solid support for large-scale application. Attached Figure Description

[0024] Figure 1 A flowchart illustrating the preparation method of the modified steel slag anti-icing aggregate provided by the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0026] Example 1:

[0027] To address the dual challenges of short production cycles, high pollution, low steel slag utilization, and difficulty in controlling f-CaO expansion in existing road anti-icing materials, Example 1 of this application provides a steel slag-based slow-release anti-icing aggregate. The free calcium oxide (f-CaO) content within this aggregate is significantly reduced through chemical reaction, while its microporous structure efficiently loads an anti-icing agent. On one hand, this material possesses high strength to meet the load-bearing and usage requirements of road engineering; on the other hand, it achieves excellent slow-release anti-icing effects, fundamentally overcoming the shortcomings of traditional surface spreading methods, such as short production cycles, low efficiency, and high pollution. Simultaneously, its preparation process must balance simplicity and efficiency, fully utilizing low-cost steel slag raw materials. Ultimately, through the concept of "treating harm with waste," it simultaneously solves two major industry challenges: the hazards of icing on cold-weather roads and the resource utilization of steel slag.

[0028] Specifically, the slow-release anti-icing aggregate based on steel slag modification provided in Example 1 of this application is prepared by the following method:

[0029] Raw material ratio:

[0030] Steel slag granules: 2.0kg, particle size 3-5mm

[0031] Anti-coagulating agent: 0.3 kg of calcium acetate

[0032] Reaction accelerator: Acetic acid 0.03 kg

[0033] Post-treatment agents: 0.02 kg of KH560 silane coupling agent and 0.04 kg of EVA waterproof dispersion.

[0034] Preparation method:

[0035] (1) Select steel slag, screen it to 3-5mm particles, remove metallic iron impurities by magnetic separation, and obtain 2.0kg of steel slag;

[0036] (2) Dissolve 0.3 kg of calcium acetate and 0.03 kg of acetic acid in 2.0 L of deionized water and stir until completely dissolved;

[0037] (3) Immerse the pretreated steel slag in the solution of step (2) and place it in a constant temperature water bath at 85℃ and mechanically stir for 18 hours.

[0038] (4) After the reaction is complete, vacuum filter to drain the steel slag particles and transfer them to a 70℃ forced-air drying oven to dry to constant weight.

[0039] (5) Heat the steel slag in step (4) to 70°C, and use a spraying device to uniformly spray the post-treatment agent to obtain modified steel slag anti-icing aggregate.

[0040] Example 2:

[0041] A slow-release anti-icing aggregate based on steel slag modification is prepared by the following method:

[0042] Raw material ratio:

[0043] Steel slag particles: 2kg, particle size 5-10mm

[0044] Anti-coagulating agent: 0.2 kg calcium chloride and 0.1 kg magnesium acetate

[0045] Reaction accelerator: Citric acid 0.02kg

[0046] Post-treatment agents: 0.02 kg of KH570 silane coupling agent and 0.04 kg of organosilicon resin.

[0047] Preparation method:

[0048] (1) Select 5-10mm steel slag particles, remove metallic iron impurities by magnetic separation, and obtain 2kg of steel slag;

[0049] (2) Dissolve 0.2 kg of calcium chloride, 0.1 kg of magnesium acetate, and 0.02 kg of citric acid in 2 L of deionized water and stir until completely dissolved;

[0050] (3) Immerse the pretreated steel slag in the solution of step (2) and place it in a constant temperature water bath at 85℃ and mechanically stir for 18 hours.

[0051] (4) After the reaction is complete, vacuum filter to drain the steel slag particles and transfer them to a 70℃ forced-air drying oven to dry to constant weight.

[0052] (5) Heat the steel slag in step (4) to 70°C, and use a spraying device to uniformly spray the post-treatment agent to obtain modified steel slag anti-icing aggregate.

[0053] Example 3:

[0054] A slow-release anti-icing aggregate based on steel slag modification is prepared by the following method:

[0055] Raw material ratio:

[0056] Steel slag particles: 2kg, particle size 3-10mm

[0057] Anti-coating agent: Potassium acetate 0.45 kg

[0058] Reaction accelerator: Ammonium chloride 0.02 kg

[0059] Post-treatment agents: 0.02 kg of KH550 silane coupling agent and 0.04 kg of acrylate.

[0060] Preparation method:

[0061] (1) Select steel slag, screen it to 3-10mm particles, remove metallic iron impurities by magnetic separation, and obtain 2kg of steel slag;

[0062] (2) Dissolve 0.45 kg of potassium acetate and 0.02 kg of ammonium chloride in 2 L of deionized water and stir until completely dissolved;

[0063] (3) Immerse the pretreated steel slag in the solution of step (2) and place it in a constant temperature water bath at 85℃ and mechanically stir for 18 hours.

[0064] (4) After the reaction is complete, vacuum filter to drain the steel slag particles and transfer them to a 70℃ forced-air drying oven to dry to constant weight.

[0065] (5) Heat the steel slag in step (4) to 70°C, and use a spraying device to uniformly spray the post-treatment agent to obtain modified steel slag anti-icing aggregate.

[0066] Comparative Example 1:

[0067] The difference from Example 1 is that the steel slag particle size is changed to 0-3mm; otherwise, it is the same as Example 1.

[0068] Comparative Example 2:

[0069] The difference from Example 1 is that the reaction promoter acetic acid is not used; otherwise, it is the same as Example 1.

[0070] Comparative Example 3:

[0071] The difference from Example 2 is that the anti-crystallizing agent is replaced with 0.2 kg of calcium chloride, and magnesium acetate is not used; otherwise, it is the same as Example 2.

[0072] Comparative Example 4:

[0073] Difference from Example 2: No post-treatment agent is used; otherwise, it is the same as Example 2.

[0074] Table 1. Performance of the slow-release anti-icing aggregates obtained in Examples 1-3 and Comparative Examples 1-4

[0075]

[0076] The above results indicate that:

[0077] The modified steel slag anti-icing aggregates prepared in Examples 1-3 exhibit balanced and excellent comprehensive performance. Their hardness is stable at 25.8-27.1 MPa, the f-CaO conversion rate reaches 86.3%-88.1%, the anti-icing temperature is maintained in the efficient range of -10.8℃ to -12.2℃, and the bond strength with asphalt reaches 4.0-4.5 MPa, which fully meets the core requirements of road engineering for aggregate bearing capacity, stabilization effect and anti-icing function.

[0078] Comparative Example 1 uses steel slag with a small particle size of 0-3 mm. Its f-CaO conversion rate is 78.5% and its anti-icing temperature is -8.3℃, both of which are lower than those of Example 1 (3-5 mm particle size). This is because steel slag with too small a particle size is prone to particle agglomeration, which makes it difficult for the free calcium oxide inside to fully contact the reaction solution, thus affecting the overall performance.

[0079] Comparative Example 2, without the addition of a reaction promoter, had an f-CaO conversion rate of only 62.3%, a hardness that plummeted to 18.7 MPa, and an anti-icing temperature of only -3.9°C, which was significantly worse than the Example. This demonstrates that reaction promoters such as acetic acid and citric acid can effectively accelerate the directional reaction of free calcium oxide in steel slag, and are key factors in ensuring the stabilization of steel slag and the efficient loading of anti-icing agents.

[0080] Comparative Example 3 used calcium chloride as the anti-icing agent. Although it had the lowest anti-icing temperature (-15.0℃), the bonding strength was slightly lower than that of Example 2. It also did not demonstrate the environmental advantages of acetate-based anti-icing agents. This indicates that the anti-icing agent system using a combination of chloride and acetate can ensure the anti-icing effect while taking into account the interfacial bonding performance between aggregates and asphalt and environmental friendliness.

[0081] Comparative Example 4, which was not sprayed with post-treatment agent, had an anti-icing temperature of only -6.5℃, a bonding strength of 3.1MPa, and a hardness lower than that of Example 2. This indicates that the composite hydrophobic film formed by the post-treatment agent can not only regulate the slow release rate of the anti-icing agent and prevent its rapid dissolution and failure, but also enhance the integrity of the particle surface structure and improve the mechanical properties and interfacial bonding ability of the aggregate.

Claims

1. A modified steel slag anti-icing aggregate, characterized in that, The modified steel slag anti-icing aggregate uses steel slag as the matrix, with a free calcium oxide content of less than 2.0% and an anti-icing agent loaded in its microporous structure. By mass, the aggregate is made of the following components: 90-100 parts steel slag particles; 15-30 parts anti-icing agent; 0.2-2 parts reaction promoter; and 1-3 parts post-treatment agent.

2. The modified steel slag anti-icing aggregate according to claim 1, characterized in that, The steel slag particles have a particle size of 3-10 mm and a CaO mass content of more than 50% in the steel slag.

3. The modified steel slag anti-icing aggregate according to claim 2, characterized in that, The anti-icing agent is selected from at least one of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate.

4. The modified steel slag anti-icing aggregate according to claim 3, characterized in that, The reaction promoter is selected from at least one of acetic acid, citric acid, and ammonium chloride.

5. The modified steel slag anti-icing aggregate according to claim 4, characterized in that, The post-treatment agent includes a silane coupling agent and a waterproof dispersion; the silane coupling agent is selected from one of KH550, KH560 or KH570; the waterproof dispersion is selected from at least one of ethylene-vinyl acetate copolymer, acrylate, polyurethane or silicone resin.

6. A method for preparing the modified steel slag anti-icing aggregate as described in claim 1, characterized in that, include: Step 1: Crush and screen the steel slag to obtain steel slag particles with a particle size of 3-10 mm, and then perform magnetic separation to remove impurities; Step 2: Dissolve the anti-icing agent and reaction accelerator in water to prepare a solution with a mass concentration of 20% to 40%; Step 3: Immerse the steel slag particles obtained in Step 1 into the solution obtained in Step 2, control the liquid-solid mass ratio to be 1:1 to 2:1, and stir the mixture at a constant temperature of 60 to 95°C for 12 to 24 hours. Step 4: Separate the reaction materials into solid and liquid phases, and dry the resulting solid particles at 40-60°C to constant weight; Step 5: Heat the dried solid particles to 50-80℃ and keep them at that temperature. Then, spray the post-treatment agent evenly onto the surface of the hot solid particles to obtain modified steel slag anti-icing aggregate.

7. The method for preparing modified steel slag anti-icing aggregate according to claim 6, characterized in that, In step 2, the anti-icing agent is selected from at least one of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate.

8. The method for preparing modified steel slag anti-icing aggregate according to claim 7, characterized in that, In step 2, the reaction promoter is selected from at least one of acetic acid, citric acid, and ammonium chloride, and the amount added is 0.2 to 2 parts based on the mass of the steel slag particles.

9. The method for preparing modified steel slag anti-icing aggregate according to claim 8, characterized in that, Step 4, after solid-liquid separation, also includes a residual liquid recycling process: lime milk is added to the separated residual liquid to adjust the pH to 8-10, polyaluminum chloride or polyacrylamide flocculant is added to precipitate heavy metal ions, and the resulting supernatant is reused for solution preparation in step 2.

10. The method for preparing modified steel slag anti-icing aggregate according to claim 9, characterized in that, In step 5, the mass ratio of silane coupling agent to waterproof dispersion in the post-treatment agent is 1:2 to 1:4; the silane coupling agent is selected from one of KH570, KH560, and KH550; the waterproof dispersion is selected from at least one of ethylene-vinyl acetate copolymer, acrylate, polyurethane, and silicone resin.

Images