A modified iron tailings road base material and its preparation and application methods

Abstract

The application belongs to the technical field of road base and industrial waste treatment, and discloses a modified iron tailing road base material and a preparation and application method thereof. In the road base material, only the iron tailing is used as the stabilizing material, and cement is used as the cementing material, so that the iron tailing is consumed on a large scale, the utilization rate of the iron tailing resources is improved, and the shortage of road engineering sand and gravel is relieved. In the application, soluble sodium salt and KH-550 are used to form modifier A, and castor oil sodium sulfonate, triisopropanolamine and sodium tetradecyl sulfate are used to form modifier B. The iron tailing is modified by using the modifier A first, so that the iron tailing surface has strong electronegativity and the synergistic effect with the modifier B is enhanced. Then, the modified iron tailing is further mixed with the modifier B, so that the compactness of the iron tailing road base material is effectively improved, the compressive strength of the iron tailing road base material is improved, and the water stability of the iron tailing road base material is improved.

Description

Technical Field

[0001] This invention relates to the field of road base course and industrial waste treatment technology, specifically to a modified iron tailings for road base course and its preparation and application methods. Background Technology

[0002] As the world's largest steel producer, my country has a surplus of low-grade iron ore, with few high-grade deposits. Statistics show that producing 1 ton of iron concentrate generates 2.5 to 3 tons of iron tailings. With the increasing depletion of iron ore resources in my country, the amount of iron tailings produced will be even greater. Long-term development has accumulated a large amount of iron tailings waste, but the comprehensive utilization rate of iron tailings is only about 7%. The operating cost of tailings dams can account for more than 30% of the production cost of a typical mine concentrator. Finding a new way to utilize iron tailings can not only save resources but also eliminate the safety hazards they pose.

[0003] With the continuous development of my country's social economy and the expanding scope of highway construction at all levels, some problems with road base courses have inevitably emerged. Firstly, semi-rigid base courses are predominantly used in my country's road surfaces. Due to the characteristics of semi-rigid base materials, cracking occurs due to thermal shrinkage and drying shrinkage, which then reflects and damages the asphalt layer. Secondly, semi-rigid base courses consume large amounts of materials; cement-stabilized crushed stone base courses require extensive quarrying, which easily leads to vegetation destruction and soil erosion, causing irreversible damage to nature. Moreover, with increasingly scarce resources, material costs are rising sharply. Therefore, how to rationally utilize local materials and reduce the use of natural sand and gravel while meeting road base course design requirements has become a problem that researchers in the field of road engineering need to solve.

[0004] Currently, domestic patented technologies for preparing road base courses using iron tailings generally focus on the following aspects:

[0005] Patent CN111003984A discloses a novel iron tailings mixed soil road base material and its preparation method. This patent uses ordinary soil, iron tailings sand, cement, lime, ionic soil stabilizer, and polypropylene fiber to prepare the road base. Although the 7-day unconfined compressive strength reaches 6.5 MPa, the preparation process requires the use of highly corrosive reagents such as concentrated sulfuric acid, which is detrimental to construction. Furthermore, the preparation cost of the stabilizer is relatively high. In addition, soil variations are significant in different regions, especially when clay with a high plasticity index is combined with iron tailings, making construction more difficult.

[0006] Patent CN114890768A discloses a road base material made from iron tailings, its preparation method, and its application. This patent utilizes modified polymers, quicklime, fly ash, magnesium salts, calcium salts, and iron tailings to prepare the road base material. Although the mixture contains 100% iron tailings, which can solve the problem of large-scale utilization of iron tailings and reduce construction costs, the preparation process requires heating water to 30-50℃ before adding the modified polymers, which is inconvenient for actual construction. Furthermore, the 7-day unconfined compressive strength is only slightly higher than the strength of lime-stabilized soil as a base layer as specified in JTG D50-2017. Under actual construction conditions, the overall base layer strength is difficult to guarantee effectively. In addition, the production cost of this technology needs further reduction.

[0007] Patent CN109336506A discloses a curing agent with strong curing ability and its application method. This patent utilizes an active mixed material, microsilica fume, cement, sulfate activator, calcium alkali, and superabsorbent resin. While it can improve the early strength of iron tailings backfill, especially for iron tailings sand with high moisture content, the raw materials require high-temperature calcination and grinding, increasing production costs. Furthermore, the curing effect of the curing agent is only average and needs further improvement.

[0008] Patent CN109663563A discloses a modified iron tailings sand, its preparation, and its application. This patent utilizes iron tailings and antibiotic bacterial residue. While it can improve the adsorption performance of heavy metal ions and phosphorus compared to unmodified iron tailings sand, its preparation process is complex. It requires first mixing the antibiotic bacterial residue and iron tailings to form a mixture, then subjecting it to anaerobic pyrolysis and carbonization, followed by rinsing until the pH is neutral. This complex preparation process makes it economically unadvantageous.

[0009] Therefore, no existing technology has proposed a base course material for iron tailings pavement that can reduce production costs, enhance roadbed water stability, improve compressive strength, and be widely applied. Summary of the Invention

[0010] To address the shortcomings of iron tailings in road construction, such as low utilization rate, high production cost, and poor overall strength, the present invention aims to provide a modified iron tailings road base material and its preparation and application methods. By modifying the iron tailings, the material's activity is improved, the curing effect of the modification is enhanced, and the production cost is reduced, so that the technical indicators of the modified iron tailings road base material meet the requirements of JTG D50-2017 "Specifications for Design of Highway Asphalt Pavement".

[0011] To achieve the above objectives, the present invention is implemented through the following technical solution: a modified iron tailings road base material, wherein the base material comprises the following components in parts by weight: 90-108 parts modified iron tailings, 0.09-0.11 parts modifier B, 3.6-5.4 parts cement, and 9-12.6 parts tap water;

[0012] The modifier B comprises the following components by weight: 2-8 parts sodium castor oil sulfonate, 0.4-0.8 parts triisopropanolamine, and 1-2 parts sodium tetradecyl sulfate;

[0013] The modified iron tailings have a particle size of less than 4.75 mm. The modified iron tailings are modified from the following raw materials by weight: 3-5 parts modifier A, 40-60 parts iron tailings and 150-200 parts water.

[0014] The modifier A comprises, by weight, 2-4 parts of soluble sodium salt and 0.1-0.5 parts of silane coupling agent.

[0015] The modified iron tailings are modified with modifier A, which makes the iron tailings surface exhibit strong electronegativity, enhancing the synergistic effect with modifier B. After modification, the surface binding energy of Al, Si, and Ca in the iron tailings is reduced, and the transition ability of the outermost electrons of the atoms is enhanced, thereby improving the reactivity of its oxides. The small amount of active silica and alumina in the iron tailings material can react with calcium hydroxide to form hydration products such as calcium silicate and calcium aluminate, improving the early strength of the tailings material. Furthermore, the iron tailings with a particle size of less than 4.75 mm contain many ultrafine particles, which can improve particle size distribution, achieve close packing, increase the number of central particles, and to a certain extent act as micro-aggregate fillers, which is beneficial to improving the water stability of the tailings material, reducing water absorption, and enhancing the strength of the modified iron tailings pavement base material.

[0016] The silane coupling agent is KH-550, which can improve material compatibility. Its surface is rich in active amino groups. The main oxides (SiO2, Fe3O4) of iron tailings are covered with hydroxyl groups. The hydroxyl groups on the surface will chemically bond with the carboxyl groups of KH-550 to generate Si-O-CH2CH3 groups, which graft KH-550 onto the surface of iron tailings. The R group (H2N(CH2)3) at the other end can combine with organic materials such as asphalt to generate reactive groups, thereby enhancing the adhesion to the interface of asphalt mixtures to a certain extent and improving its road performance.

[0017] Sodium castor oil sulfonate, used as a modifier to suppress water absorption, is readily soluble in water and consists of a hydrophilic head (sulfonic acid -SO3H) and a hydrophobic tail (carbon and hydrogen atoms), exhibiting a dual structure. This allows the sulfonate anion to directly form a chemical chain with the metal cations on the iron tailings surface, with the hydrogen atoms between them forming an inductive chain. The structural unit primarily uses face-to-face and edge-to-face contacts. Due to the grafting of sulfonates, bound water on the iron tailings surface is displaced, effectively inhibiting water absorption by the iron tailings. Simultaneously, the hydrocarbon group, acting as the hydrophobic tail, attracts negatively charged silica-alumina phase particles, causing them to hydrate within the iron tailings particles, producing CSH gel and ettringite, resulting in a denser overall structure and improved water stability.

[0018] Triisopropanolamine plays a role in promoting early strength in modifiers. Due to its strong polarity, it can reduce the free energy of the surface of slag and cement particles, prevent particle agglomeration, increase the specific surface area of ​​particles, accelerate the hydration rate, and increase the amount of hydration products. Furthermore, after triisopropanolamine dissolves in water, its amine groups are attracted by the modified iron tailings with strong electronegativity, which can promote hydration near the iron tailings particles. This causes the hydration products CSH, AFt, and Ca(OH)2 to grow around the particles, making the originally loose structure compact, improving density, and enhancing water stability.

[0019] Sodium tetradecyl sulfate improves anionic surface activity in modifiers. It is stable in alkaline conditions and has a strong ability to reduce surface tension. Its molecular structure contains a long-chain alkyl group and a short benzenesulfonate ion. The benzenesulfonate ion, as a polar group, acts as a "hydrophilic head" and is attracted to the strong electronegativity of the iron tailings surface. It plays a role around the iron tailings particles, reduces the size of the pores between particles, and improves the water stability of iron tailings road base materials.

[0020] Furthermore, the soluble sodium salt includes any one of sodium hydroxide, sodium silicate, and sodium aluminate. The soluble sodium salt, comprising any one of sodium hydroxide, sodium silicate, and sodium aluminate, can alter alkalinity to promote hydration. Simultaneously, the soluble sodium salt dissociates in water to form an electrolyte, imparting a strong charge to the particle surface, increasing the charge repulsion between particles, and inhibiting the agglomeration of iron tailings, thereby increasing the stability of the system.

[0021] Furthermore, the iron tailings are high-silicon iron tailings with SiO2 ≥ 75%, preferably with a plasticity index of 15.6 and an optimal moisture content of 10.3%.

[0022] Furthermore, the cement is ordinary Portland cement with a strength grade of 42.5.

[0023] This invention also discloses a method for preparing the above-mentioned modified iron tailings road base material, comprising the following steps:

[0024] (1) Weigh modifier A and water according to the proportion, and prepare the modified solution. The pH value of the modified solution should be prepared according to the needs, generally greater than 9.

[0025] (2) Weigh out iron tailings with a particle size of less than 4.75 mm according to the proportion, soak them in the modification solution at room temperature for 8-12 hours, and then dry the iron tailings slurry to make modified iron tailings with a particle size of less than 4.75 mm.

[0026] (3) After the modifier B, modified iron tailings, cement and water are weighed in proportion and mixed evenly, a compaction test is carried out to determine the maximum dry density and optimum moisture content; the inorganic binder specification requires finding the maximum dry density and optimum moisture content;

[0027] (4) Weigh out the various raw materials according to the proportion, set the moisture content 1%-2% higher than the optimum moisture content as the preset moisture content, spray 80% water onto the modified iron tailings, stir thoroughly, seal and let stand for 6-8 hours.

[0028] (5) After the curing process is completed, add the weighed cement to the sealed mixture and mix it again.

[0029] (6) Mix the remaining 20% ​​water with modifier B, spray the mixture onto the substrate, and stir until homogeneous to obtain the modified iron tailings road base material. Adding water in batches during the preparation process allows the modifier to function more effectively; adding water in other proportions cannot achieve the technical effect of improving the performance of the modified iron tailings road base material as described in this invention.

[0030] Furthermore, the drying temperature in step (2) is 95-115°C. At this temperature, the material can be dried more quickly and thoroughly.

[0031] Furthermore, in step (2), the iron tailings are poured into the modification liquid, stirred evenly with a glass rod, and then soaked and modified under sealed conditions. The glass rod does not react chemically or physically with the raw materials, and other stirring materials can also be used as long as they do not react with the raw materials. Soaking and modification under sealed conditions can avoid external influences.

[0032] Furthermore, in step (2), the iron tailings are dried before use.

[0033] The present invention also discloses the application of the above-mentioned modified iron tailings road base material in roadbed construction, wherein the modified iron tailings base material is used for roadbed construction.

[0034] The mechanism of action of the modified iron tailings road base material of this invention is mainly manifested in:

[0035] Surface modification of iron tailings mainly relies on the adsorption, reaction, and coating of iron tailings particles by soluble sodium salts and silane coupling agents, combined with sodium castor oil sulfonate, etc. Surface chemical coating modification is also the most commonly used method for tailings surface modification.

[0036] The carboxyl groups of KH-550 react with the hydroxyl groups covering the surface of iron tailings to generate Si-O-CH2CH3 groups, grafting KH-550 onto the surface of iron tailings and improving its compatibility with organic materials. Combined with sodium castor oil sulfonate, an organic compound added during molding, sodium castor oil sulfonate can exchange and adsorb ions on the surface of iron tailings and form hydrogen bonds, increasing interfacial adhesion and reducing the water absorption rate of iron tailings. The addition of triisopropanolamine and sodium tetradecyl sulfate promotes the hydration reaction, and the hydration products CSH, AFt, and Ca(OH)2 make the originally loose structure more compact. At the same time, the long-chain alkyl groups reduce surface tension and improve the water stability of the modified iron tailings pavement base material.

[0037] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0038] The modified iron tailings road base material provided by this invention uses only iron tailings as the stabilized material and cement as the binder, which realizes the large-scale consumption of iron tailings, improves the resource utilization rate of iron tailings, and alleviates the shortage of sand and gravel materials for road engineering.

[0039] This invention utilizes a modifier A composed of soluble sodium salt and KH-550, and a modifier B composed of sodium castor oil sulfonate, triisopropanolamine, and sodium tetradecyl sulfate. First, modifier A is used to modify the iron tailings, making the iron tailings surface exhibit strong electronegativity and enhancing its synergistic effect with modifier B. Then, modifier B is further mixed with the modified iron tailings, effectively improving the compactness of the iron tailings pavement base material, thereby increasing its compressive strength and water stability.

[0040] Through testing, the modified iron tailings pavement base material proposed in this invention meets the requirements of cement-stabilized subbase for expressways and Class I highways for extremely heavy and special traffic in the "Specifications for Design of Highway Asphalt Pavement" (JIGD502017), and its unconfined compressive strength can reach more than 5 MPa.

[0041] In addition, the modified iron tailings pavement base material proposed in this invention can enhance the adhesion between the pavement base material and the asphalt interface because one end of KH-550 at the interface can form a chemical bond with the iron tailings and the other end can combine with asphalt to generate reactive groups. This improves the problem of weak adhesion caused by the presence of organic-inorganic interface and increases the service life of asphalt pavement. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Unless otherwise specified, all reagents or instruments used, unless otherwise indicated, are conventional products that can be purchased commercially.

[0043] All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The specific examples and data described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] A modified iron tailings road base material, the base material comprising the following components in parts by weight: 90-108 parts modified iron tailings, 0.09-0.11 parts modifier B, 3.6-5.4 parts cement, and 9-12.6 parts tap water.

[0045] The modifier B comprises, by weight: 2-8 parts sodium castor oil sulfonate, 0.4-0.8 parts triisopropanolamine, and 1-2 parts sodium tetradecyl sulfate.

[0046] The modified iron tailings have a particle size of less than 4.75 mm and are modified from the following raw materials by weight: 3-5 parts modifier A, 40-60 parts iron tailings and 150-200 parts water.

[0047] The modifier A comprises, by weight, 2-4 parts of soluble sodium salt and 0.1-0.5 parts of silane coupling agent.

[0048] The preparation method of the above-mentioned modified iron tailings includes the following steps:

[0049] Step 1: Crush the dried iron tailings and pass them through a 4.75mm sieve for later use.

[0050] Step 2: Mix 3-5 parts of modifier A solution with 150-200 parts of water to prepare a modified solution.

[0051] Step 3: By weight fraction, pour 40-60 parts of the sieved iron tailings into the modification liquid and stir evenly with a glass rod to obtain mixture I.

[0052] Step 4: Immerse the mixture I under sealed conditions at room temperature for 8-12 hours for modification.

[0053] Step 5: Pour off the clear liquid from the natural sedimentation of mixture I, and dry and pulverize the remaining liquid. Pass it through a 4.75mm sieve to obtain modified iron tailings.

[0054] The drying temperature in both step one and step five is 95-115℃.

[0055] The preparation method of the above-mentioned modified iron tailings road base material includes the following steps:

[0056] Step 1: Weigh the modified iron tailings, cement, and water according to the proportions, mix them evenly, and conduct a compaction test to determine the maximum dry density and optimum moisture content.

[0057] Step 2: Weigh the modified iron tailings according to the specified proportions.

[0058] Step 3: Add water at a rate 1%-2% higher than the measured optimum moisture content, spray 80% of the water onto the mixture, stir thoroughly, and seal the mixture in a bag for 6-8 hours.

[0059] Step 4: After the curing process is complete, add the weighed cement to the mixture and mix it a second time.

[0060] Step 5: Add the weighed modifier B to the remaining 20% ​​of water, spray it onto the mixture, and stir thoroughly to obtain the modified iron tailings road base material.

[0061] Example 1:

[0062] This embodiment provides a modified iron tailings road base material, comprising the following components by weight: 99 parts modified iron tailings, 4.5 parts cement, and 10.8 parts tap water.

[0063] The cement mentioned is grade 42.5 silicate cement.

[0064] The modifier comprises the following components by weight: 3 parts soluble sodium salt and 0.3 parts KH-550 to form modifier A; and 5 parts sodium castor oil sulfonate, 0.6 parts triisopropanolamine, and 1.5 parts sodium tetradecyl sulfate to form modifier B.

[0065] The mass ratio of modifier A to iron tailings is 1:10.

[0066] The modifier A is used in a 1:3 mass ratio of iron tailings to water.

[0067] The mass ratio of modifier B to modified iron tailings is 1:10. This ratio facilitates construction and makes it easy to control the mass ratio.

[0068] Add 2.4g of triisopropanolamine and 6g of sodium tetradecyl sulfate to 20g of castor oil sodium sulfate, place it on a magnetic stirrer, cover it with plastic wrap and stir for 45 minutes to obtain modifier B.

[0069] The preparation method of the above-mentioned base material is as follows:

[0070] (1) Weigh modifier A and water according to the proportion, prepare the modification solution, add iron tailings according to the proportion, stir thoroughly, soak for 10 hours, take the soaked iron tailings slurry and dry it in a 105℃ dryer to obtain the treated modified iron tailings.

[0071] (2) Weigh the modified iron tailings, cement, and water according to the mass ratio, mix them thoroughly, and then conduct a compaction test to determine the optimum moisture content MC.佳 It is 10.3%, and the maximum dry density ρ max It is 2.27 g / cm 3 .

[0072] (3) The optimum moisture content MC 佳 Increase the preset moisture content MC of the mixture by 1.5 percentage points, that is, take 11.8% as the final moisture content that the mixture needs to reach.

[0073] (4) Weigh the modified iron tailings according to the proportion, mix them with 80% water to obtain a mixture, and seal it in a sealed bag for 6 hours.

[0074] (5) After the curing process is completed, add cement and mix thoroughly.

[0075] (6) Add the weighed modifier B to the remaining 20% ​​of water, spray it onto the mixture, and stir thoroughly to obtain the modified iron tailings road base material.

[0076] The modified iron tailings road base material prepared above was molded, and the molded product was demolded and then placed in a standard curing box with a temperature of 20±1℃ and a relative humidity of 95% for 6 days of curing and 1 day of water curing for subsequent test.

[0077] Example 2:

[0078] This embodiment provides a modified iron tailings road base material, comprising the following components by weight: 90 parts modified iron tailings, 3.6 parts cement, and 9 parts tap water.

[0079] The modifier comprises the following components by weight: 2 parts soluble sodium salt and 0.1 parts KH-550 to form modifier A; 2 parts sodium castor oil sulfonate, 0.4 parts triisopropanolamine and 1 part sodium tetradecyl sulfate to form modifier B.

[0080] The specific preparation method is the same as in Example 1.

[0081] Example 3:

[0082] This embodiment provides a modified iron tailings road base material, comprising the following components by weight: 108 parts modified iron tailings, 5.4 parts cement, and 12.6 parts tap water.

[0083] The modifier comprises the following components by weight: 4 parts soluble sodium salt and 0.5 parts KH-550 to form modifier A; 8 parts sodium castor oil sulfonate, 0.8 parts triisopropanolamine, and 2 parts sodium tetradecyl sulfate to form modifier B.

[0084] The specific preparation method is the same as in Example 1.

[0085] Comparative Example 1:

[0086] Unlike Example 1, modifier A was not added in the comparative example; otherwise, the materials were prepared using the same method. Data from Tables 1 and 2 show that the pretreatment of iron tailings using modifier A is a necessary step in this application. This also indicates that modifier B needs to be used in combination with modifier A to achieve the goal of improving the compressive strength and resistance to drying shrinkage strain of the modified iron tailings road base material.

[0087] Comparative Example 2:

[0088] Unlike Example 1, modifier B was not added in the comparative example; otherwise, the materials were prepared using the same method. Data from Tables 1 and 2 show that the strength of the modified iron tailings road base material is reduced when modifier B is absent. This further illustrates that modifier A needs to be used in combination with modifier B to improve the compressive strength and resistance to drying shrinkage strain of the modified iron tailings road base material.

[0089] Comparative Example 3:

[0090] Unlike Example 1, modifiers A and B were not added in the comparative example; otherwise, the materials were prepared using the same method as in Example 1. Data from Tables 1-3 show that when both modifiers A and B are absent, the strength of the resulting iron tailings road base material decreases significantly, the water absorption rate increases significantly, and the activity and curing effect also deteriorate markedly.

[0091] Comparative Example 4:

[0092] Unlike Example 1, in the comparative example, water was sprayed onto the modified iron tailings in one go, while the rest was the same as in Example 1, and the required materials were prepared using the same method. The data in Table 1 show that the phased addition of water during the preparation process has a significant impact on the final strength of the modified iron tailings road base material.

[0093] Comparative Example 5:

[0094] Unlike Example 1, the soaking time in the comparative example was changed to 1 hour, while the rest was the same as in Example 1, and the required materials were prepared using the same method. The data in Table 1 shows that when modifying iron tailings with modifier A, if the corresponding time requirement is not met, the goal of improving the strength of the modified iron tailings road base material cannot be achieved.

[0095] The iron tailings road base materials in Examples 1-3 and Comparative Examples 1-3 were used to prepare cylindrical specimens of Ф50mm×50mm using a universal press in accordance with the requirements for unconfined compressive strength testing of inorganic binder stabilized materials in the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTGE51-2009). At least 6 specimens were prepared in each group. After preparation, the specimens were sealed and placed in a curing chamber for curing (curing temperature 20℃, curing humidity above 95%). After curing for 6 days, the specimens were taken out and then immersed in water for one day. After completion, the surface moisture of the specimens was wiped dry, and the compressive strength of the specimens was tested using a pavement strength tester.

[0096] The experimental results are shown in Table 1:

[0097] Table 1

[0098]

[0099]

[0100] Examples 1-3 and Comparative Examples 1-3 were prepared according to the requirements for drying shrinkage testing of inorganic binder stabilized materials in the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTGE51-2009). Rectangular specimens measuring 50mm × 50mm × 200mm were prepared, sealed, and placed in a standard curing room (curing temperature 20°C, relative humidity above 95%) for curing. After 28 days of curing, the drying shrinkage strain of the pavement base material relative to its pre-curing state was tested, and the drying shrinkage coefficient was used to evaluate the test results.

[0101] The experimental results are shown in Table 2:

[0102] Table 2

[0103]

[0104] The optimal ratio selected in Example 1 resulted in a road base material with excellent resistance to drying shrinkage strain.

[0105] Organic carbon adsorption tests were conducted on Example 1 and Comparative Example 3 according to the following steps.

[0106] Weigh 30g of modified iron tailings sample and place it in a 1L plastic bottle. Add 450ml of deionized water and mix. Place the mixture on a constant temperature shaker and shake (200r·min-1) for 1h. After shaking, transfer the solution in the plastic bottle to 100mL centrifuge tubes in batches and centrifuge in a high-speed refrigerated centrifuge for 15min. Filter the supernatant after centrifugation through a 0.45μm filter membrane. The collected filtrate is the DOC mother liquor.

[0107] The experimental results are shown in Table 3:

[0108] Table 3

[0109] Test materials Balancing time / h Adsorption constant Kf Example 1 24 0.2 Comparative Example 3 24 0.6

[0110] According to the formulation in Example 1, the road base material prepared using modified iron tailings effectively improves its own activity and enhances the modification and curing effect.

Claims

1. A modified iron tailings road base material, characterized in that, The base material comprises the following components by mass: modified iron tailings 90-108 parts, modifier B 0.09-0.11 parts, cement 3.6-5.4 parts, tap water 9-12.6 parts; The modifier B comprises the following components: 2-8 parts of sodium ricinoleate, 0.4-0.8 parts of triisopropanolamine, and 1-2 parts of sodium myristyl sulfate. The modified iron tailings have a particle size of less than 4.75 mm, and are modified from the following raw materials by weight fraction: 3-5 parts of modifier A, 40-60 parts of iron tailings, and 150-200 parts of water. The modifier A comprises the following components: 2-4 parts of soluble sodium salt and 0.1-0.5 parts of silane coupling agent.

2. The modified iron tailings road base material according to claim 1, characterized in that: The soluble sodium salt comprises any one of sodium hydroxide, sodium silicate, and sodium metaaluminate.

3. The modified iron tailings road base material according to claim 1, characterized in that: The iron tailings are high-silicon iron tailings with SiO2≥75%.

4. The modified iron tailings road base material according to claim 1, characterized in that: The cement is ordinary Portland cement with a strength grade of 42.

5.

5. A process for the preparation of the modified iron tailings road base material as claimed in any one of claims 1 to 4, characterised in that, The method comprises the following steps: (1) The modifier A and water are weighed according to the proportion, a modified liquid is prepared, the iron tailings are soaked in the modified liquid at room temperature for 8-12 hours, and the iron tailings mud is dried to obtain modified iron tailings with a particle size of less than 4.75 mm; (2) The modifier B, modified iron tailings, cement, and water are weighed according to the mass proportion, mixed uniformly, and then subjected to a compaction test to measure the maximum dry density and the optimum moisture content; (3) The various raw materials are weighed according to the proportion, the moisture content greater than the optimum moisture content by 1-2% is set as the preset moisture content, 80% of the water is sprayed on the modified iron tailings, the mixture is stirred thoroughly, and the mixture is sealed and allowed to stand for 6-8 hours; (4) After the standing is completed, the weighed cement is added to the sealed mixture, and the mixture is stirred again; (5) The remaining 20% of the water is mixed with the modifier B, sprayed on the mixture, and stirred uniformly to obtain the modified iron tailings road base material.

6. The process for the preparation of modified iron tailings road base material as claimed in claim 5 wherein: The drying temperature in step (1) is 95-115°C.

7. The process for the preparation of modified iron tailings road base material as claimed in claim 5 wherein: In step (2), the iron tailings are poured into the modified liquid, stirred uniformly, and then soaked in the modified liquid under sealed conditions.

8. The process for the preparation of modified iron tailings road base material as claimed in claim 5 wherein: The iron tailings are subjected to drying treatment before use in step (2).

9. Use of the modified iron tailings road base material according to any one of claims 1 to 4 in a road base, characterized in that: The modified iron tailings base material is used for roadbed construction.

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