Preparation method of acid-etching modified copper slag powder for asphalt mortar and use method thereof

Abstract

This invention relates to a method for preparing and using acid-etched modified copper slag powder suitable for asphalt mastic. The invention aims to address the technical problems of existing methods for modifying copper slag powder for asphalt mastic, which are cumbersome, energy-intensive, and difficult to apply industrially. This invention selectively dissolves the iron oxide and iron silicate mineral phases on the surface of copper slag with dilute sulfuric acid, creating a rough, uneven microstructure on the surface of the copper slag particles. This significantly increases the specific surface area and interfacial contact area, thereby enhancing the mechanical interlocking and interfacial bonding with asphalt, effectively improving the high-temperature deformation resistance of asphalt mastic, and simultaneously realizing the resource utilization of industrial solid waste copper slag, possessing both environmental and practical value. The method of this invention is simple, easy to operate, requires no complex equipment, and can achieve industrial-scale mass production.

Description

Technical Field

[0001] This invention relates to a method for preparing modified copper slag powder that can be used in asphalt mortar and its application method. Background Technology

[0002] Fillers are the core component of asphalt mastic, and their performance directly determines the strength, high-temperature stability, fatigue cracking resistance and durability of asphalt mixtures. Currently, the fillers used in asphalt mastic are mainly mineral powders processed from minerals such as limestone and quartz. As a non-renewable mineral resource, the mining and processing of mineral powders are limited by geological conditions, and there are also problems such as high energy consumption and significant environmental pollution.

[0003] Copper slag is a major industrial solid waste generated during pyrometallurgical copper smelting. Globally, annual copper slag emissions exceed ten million tons, and my country, as a major copper smelting country, has a continuously increasing stockpile of copper slag. Existing research indicates that copper slag powder possesses certain physical and mechanical properties and can be used as a substitute for mineral powder in asphalt mortar, achieving both solid waste disposal and cost reduction. However, unmodified copper slag powder suffers from defects such as a smooth and dense surface, strong hydrophilicity, poor compatibility with asphalt, and a tendency to agglomerate, leading to unstable mechanical properties of the mortar and failing to meet application requirements for high-temperature deformation and fatigue resistance.

[0004] To address the aforementioned issues, surface modification of copper slag powder is necessary to improve its compatibility with asphalt. Existing copper slag powder modification technologies primarily rely on physical coating and high-temperature calcination, which suffer from drawbacks such as cumbersome processes, high energy consumption, and difficulty in industrial application. This invention aims to develop a copper slag powder modification method that is mild, simple to operate, low in cost, and provides stable modification effects, thereby promoting the synergistic development of high-value utilization of copper slag solid waste and performance improvement of asphalt mastics. Summary of the Invention

[0005] The present invention aims to solve the technical problems of existing methods for modifying copper slag powder that can be used in asphalt mastic, such as cumbersome processes, high energy consumption, and difficulty in industrial application, and provides a method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic and its application method.

[0006] The method for preparing acid-etched modified copper slag powder suitable for use in asphalt mastics according to the present invention is carried out according to the following steps:

[0007] 1. Slowly pour the copper slag powder into the dilute sulfuric acid etching solution, ensuring that the copper slag powder is completely immersed. Etch in sections at room temperature to form a uniform micro-rough structure on the surface of the copper slag powder.

[0008] 2. The copper slag powder is separated from the dilute sulfuric acid etching solution by suction filtration, and the solid copper slag powder is retained. Then, the copper slag powder is repeatedly washed with deionized water until the pH of the washing solution is neutral to remove residual sulfuric acid and soluble salts.

[0009] 3. Place the copper slag powder washed in step 2 into a forced-air drying oven and dry it until constant weight. Let it cool naturally to room temperature and sieve to obtain modified copper slag powder.

[0010] The method of using the acid-etched modified copper slag powder prepared in this invention, which can be used in asphalt mastics, is as follows:

[0011] Modified copper slag powder and mineral powder are mixed and stirred at 165℃~175℃ to obtain a mixed filler. Then, the mixed filler is added to SBS modified asphalt and stirred at 165℃~175℃ to obtain acid-etched modified copper slag powder asphalt mortar.

[0012] The preparation method of this invention is simple and convenient to operate, requiring no complex equipment, and can achieve industrial-scale mass production. By selectively dissolving the iron oxide and iron silicate mineral phases on the surface of copper slag with dilute sulfuric acid, an uneven micro-rough structure is formed on the surface of the copper slag particles, which significantly increases their specific surface area and interfacial contact area, thereby enhancing the mechanical interlocking effect and interfacial bonding force with asphalt, effectively improving the high-temperature deformation resistance of asphalt mortar, and realizing the resource utilization of industrial solid waste copper slag, which has both environmental protection and practical value. Attached Figure Description

[0013] Figure 1 Microscopic morphology of copper slag powder;

[0014] Figure 2 The main viscoelastic curve of asphalt mortar at 20℃;

[0015] Figure 3 for Figure 2 A magnified view of the area within the gray box. Detailed Implementation

[0016] Specific Implementation Method 1: This implementation method is a method for preparing acid-etched modified copper slag powder that can be used in asphalt mortar, specifically carried out according to the following steps:

[0017] 1. Slowly pour the copper slag powder into the dilute sulfuric acid etching solution, ensuring that the copper slag powder is completely immersed. Etch in sections at room temperature to form a uniform micro-rough structure on the surface of the copper slag powder.

[0018] 2. The copper slag powder is separated from the dilute sulfuric acid etching solution by suction filtration, and the solid copper slag powder is retained. Then, the copper slag powder is repeatedly washed with deionized water until the pH of the washing solution is neutral to remove residual sulfuric acid and soluble salts.

[0019] 3. Place the copper slag powder washed in step 2 into a forced-air drying oven and dry it until constant weight. Let it cool naturally to room temperature and sieve to obtain modified copper slag powder.

[0020] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the preparation method of the dilute sulfuric acid etching solution in step one is as follows: A 98% sulfuric acid solution is slowly poured into a glass container filled with deionized water, while simultaneously stirring continuously at 300 rpm for 5 minutes using an electric stirrer to ensure thorough mixing of the sulfuric acid and deionized water, thus preparing a 5% sulfuric acid solution. The solution is then allowed to cool naturally to room temperature to obtain the dilute sulfuric acid etching solution. Everything else is the same as in Specific Implementation Method One.

[0021] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that the volume ratio of copper slag powder to dilute sulfuric acid etching solution in step one is 1:10. Everything else is the same as in Specific Implementation Method 2.

[0022] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: in step one, the etching process is carried out in segments at 20℃~25℃ for 12 hours. Everything else is the same as in Specific Implementation Methods One to Three.

[0023] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the specific steps of segmented stirring and etching for 12 hours described in step one are as follows:

[0024] The segmented stirring during etching is to ensure sufficient contact between the copper slag powder and the dilute sulfuric acid etching solution, avoiding over- or under-etching in certain areas. Specifically, the stirring is performed for 3 minutes each at 300 rpm at 60 minutes, 300 minutes, and 600 minutes after all the copper slag powder has been poured into the dilute sulfuric acid etching solution. The remaining time is for settling, with the total settling and stirring time being 12 hours. Other procedures are the same as in Specific Implementation Method Four.

[0025] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that: in step two, the copper slag powder is repeatedly washed with deionized water until the pH of the washing solution is 6.5-7.5 to remove residual sulfuric acid and soluble salts. Everything else is the same as in Specific Implementation Method Five.

[0026] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the drying temperature in step three is 60℃, and the powder is passed through a 200-mesh standard sieve to obtain modified copper slag powder with a particle size ≤75μm. Everything else is the same as in Specific Implementation Method Six.

[0027] Specific Implementation Method Eight: This implementation method describes the application of the acid-etched modified copper slag powder prepared in Specific Implementation Method One, which can be used in asphalt mastics. The details are as follows:

[0028] Modified copper slag powder and mineral powder are mixed and stirred at 165℃~175℃ to obtain a mixed filler. Then, the mixed filler is added to SBS modified asphalt and stirred at 165℃~175℃ to obtain acid-etched modified copper slag powder asphalt mortar.

[0029] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the mass ratio of modified copper slag powder to mineral powder in the mixed filler is 1:3; and the mass ratio of the mixed filler to SBS modified asphalt is 1:1. Everything else is the same as in Specific Implementation Method Eight.

[0030] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that: modified copper slag powder and mineral powder are mixed and stirred at 165℃~175℃ for 120s to obtain a mixed filler. Then, the mixed filler is added to SBS modified asphalt, and stirring is continued at 165℃~175℃ for 240s to obtain acid-etched modified copper slag powder asphalt mortar. Everything else is the same as in Specific Implementation Method Nine.

[0031] The invention was verified using the following experiments:

[0032] Experiment 1: This experiment demonstrates a method for preparing acid-etched modified copper slag powder that can be used in asphalt mortar. The specific steps are as follows:

[0033] 1. Slowly pour the copper slag powder into the dilute sulfuric acid etching solution and ensure that the copper slag powder is completely immersed. Stir and etch in sections at 25°C for 12 hours to form a uniform micro-rough structure on the surface of the copper slag powder.

[0034] The copper slag powder mentioned above is selected from dry, non-lumpy, and impurity-free copper slag powder, and then large particle impurities are removed.

[0035] The preparation method of the dilute sulfuric acid etching solution is as follows: a 98% sulfuric acid solution is slowly poured into a glass container containing deionized water, and an electric stirrer is used to continuously stir at a speed of 300 r / min for 5 min to ensure that the sulfuric acid and deionized water are fully mixed to prepare a 5% sulfuric acid solution. The solution is then naturally cooled to room temperature to obtain the dilute sulfuric acid etching solution.

[0036] The volume ratio of the copper slag powder to the dilute sulfuric acid etching solution is 1:10;

[0037] The specific steps of the segmented stirring etching for 12 hours are as follows: the segmented stirring treatment during the etching period is to ensure that the copper slag powder and the dilute sulfuric acid etching solution are in full contact, and to avoid local over-etching or under-etching. Specifically, at 60 min, 300 min and 600 min after all the copper slag powder has been poured into the dilute sulfuric acid etching solution, the mixture is stirred for 3 minutes at a speed of 300 r / min. The remaining time is left to stand. The time for standing and stirring is added together to 12 hours.

[0038] 2. The copper slag powder is separated from the dilute sulfuric acid etching solution by suction filtration, and the solid copper slag powder is retained. Then, the copper slag powder is repeatedly washed with deionized water until the pH value of the washing solution is 6.5~7.5 to remove residual sulfuric acid and soluble salts.

[0039] 3. Place the copper slag powder washed in step 2 into a forced-air drying oven and dry it until constant weight. Let it cool naturally to room temperature and sieve to obtain acid-etched modified copper slag powder.

[0040] The drying temperature in step three is 60℃, and the powder is passed through a 200-mesh standard sieve to obtain modified copper slag powder with a particle size ≤75μm.

[0041] The specific method for using the acid-etched modified copper slag powder prepared above, which can be used in asphalt mortar, is as follows:

[0042] Acid-etched modified copper slag powder and limestone powder were mixed and stirred at 165℃ for 120s to obtain a mixed filler. Then, the mixed filler was added to SBS modified asphalt and stirred at 165℃ for 240s. The mixing process parameters followed the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40-2004) to obtain acid-etched modified copper slag powder asphalt mortar.

[0043] The mass ratio of acid-etched modified copper slag powder to limestone powder in the mixed filler is 1:3; the mass ratio of the mixed filler to SBS modified bitumen is 1:1.

[0044] Comparative test: This test involves the addition of unmodified copper slag powder. The difference from test one is that the mixed filler is made by mixing unmodified copper slag powder with limestone powder. The rest is the same as test one, and the final product is unmodified copper slag powder asphalt mortar.

[0045] Performance testing and results of copper slag powder: The microstructure of unmodified copper slag powder and acid-etched modified copper slag powder prepared in Experiment 1 was characterized using field emission electron microscopy, such as... Figure 1 As shown, (a) is unmodified copper slag powder and (b) is acid-etched modified copper slag powder. It can be seen that after acid etching, the smooth outer layer structure of the copper slag powder surface is destroyed, forming an uneven microporous rough structure, and the specific surface area is increased compared with the unmodified copper slag powder.

[0046] Test results of SBS modified bitumen sealant:

[0047] 1. High-temperature deformation resistance: According to the test method of multiple stress creep and recovery (MSCR) in T0647-2025 of the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the creep performance of the unmodified copper slag powder asphalt mortar of the comparative test and the acid-etched modified copper slag powder asphalt mortar of the first test were tested under different stresses and temperatures. The results are shown in Table 1 and Table 2.

[0048] Table 1. Creep recovery rate (%) of different copper slag powder asphalt mortars

[0049]

[0050] Table 2. Irreversible creep compliance Jnr (kPa) of different copper slag powder asphalt mortars -1 )

[0051]

[0052] As shown in Tables 1 and 2, under the same stress and temperature conditions, the acid-etched modified copper slag powder mortar exhibits a higher creep recovery rate and a lower irrecoverable creep compliance (Jnr). Specifically, under high stress conditions of 58℃ and 3.2 kPa, the Jnr of the modified group is 18.8% lower than that of the unmodified group, indicating that acid etching significantly improves the mortar's resistance to permanent deformation at high temperatures and provides superior high-temperature stability.

[0053] 2. Fatigue cracking resistance: According to the linear amplitude scanning (LAS) test method in T0648-2025 of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the fatigue life of the unmodified copper slag powder asphalt mortar in the comparative test and the acid-etched modified copper slag powder asphalt mortar in the first test were tested at different strain levels. The test results are shown in Table 3.

[0054] Table 3 Comparison of fatigue life of asphalt mastic under different strain levels

[0055]

[0056] Table 3 shows that as the strain level increases from 2.5% to 10%, the fatigue life of both types of adhesives gradually decreases. The fatigue life of the modified group is consistently higher than that of the unmodified group, with the largest increase observed at the 10% high strain level. The test results indicate that appropriate acid etching modification can improve the interfacial bond strength of asphalt binders and enhance the fatigue crack resistance of asphalt adhesives.

[0057] 3. High-Temperature Rheological Properties: Based on the dynamic shear rheology (DSR) test (T0628-2011) in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E3410-2025), the viscoelastic properties of the unmodified copper slag powder asphalt mastic from the comparative test and the acid-etched modified copper slag powder asphalt mastic from Test 1 were determined. The master viscoelastic curves at 20℃ are shown below. Figure 2 As shown, Figure 3 for Figure 2 Enlarged view of the area within the gray box. It can be seen that the modulus variation patterns of both groups of asphalt mastic conform to the viscoelastic rheological characteristics of asphalt mastic, meeting the rheological performance requirements of asphalt binders in various climatic zones; at low frequencies (high-temperature equivalent state), the complex shear modulus of the modified group is significantly higher than that of the unmodified group, and the mastic stiffness and structural stability are better, confirming that acid etching modification can significantly optimize the high-temperature rheological properties of asphalt mastic.

Claims

1. A method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic, characterized in that... The preparation method is carried out according to the following steps:

1. Slowly pour the copper slag powder into the dilute sulfuric acid etching solution, ensuring that the copper slag powder is completely immersed. Etch in sections at room temperature to form a uniform micro-rough structure on the surface of the copper slag powder.

2. The copper slag powder is separated from the dilute sulfuric acid etching solution by suction filtration, and the solid copper slag powder is retained. Then, the copper slag powder is repeatedly washed with deionized water until the pH of the washing solution is neutral to remove residual sulfuric acid and soluble salts.

3. Place the copper slag powder washed in step 2 into a forced-air drying oven and dry it until constant weight. Let it cool naturally to room temperature and sieve to obtain modified copper slag powder.

2. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic according to claim 1, characterized in that... The preparation method of the dilute sulfuric acid etching solution in step one is as follows: Slowly pour a 98% sulfuric acid solution into a glass container containing deionized water, and at the same time use an electric stirrer to continuously stir at a speed of 300 r / min for 5 min to ensure that the sulfuric acid and deionized water are fully mixed to prepare a 5% sulfuric acid solution. Allow it to cool naturally to room temperature to obtain the dilute sulfuric acid etching solution.

3. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic according to claim 2, characterized in that... The volume ratio of copper slag powder to dilute sulfuric acid etching solution mentioned in step one is 1:

10.

4. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic according to claim 1, characterized in that... In step one, the etching process is carried out in stages at 20℃~25℃ for 12 hours.

5. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic according to claim 4, characterized in that... The specific steps for the segmented stirring etching for 12 hours described in Step 1 are as follows: at 60 minutes, 300 minutes and 600 minutes after all the copper slag powder has been poured into the dilute sulfuric acid etching solution, stir with an electric stirrer at a speed of 300 r / min for 3 minutes each time. Let it stand for the rest of the time. The time for standing and stirring is added together to 12 hours.

6. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mortar according to claim 1, characterized in that... In step two, the copper slag powder is repeatedly washed with deionized water until the pH of the washing solution is 6.5-7.5 to remove residual sulfuric acid and soluble salts.

7. The method for preparing acid-etched modified copper slag powder that can be used in asphalt mastic according to claim 1, characterized in that... The drying temperature in step three is 60℃, and the powder is passed through a 200-mesh standard sieve to obtain modified copper slag powder with a particle size ≤75μm.

8. A method for using acid-etched modified copper slag powder prepared as claimed in claim 1, which can be used in asphalt mortar, characterized in that... The method of use is as follows: Modified copper slag powder and mineral powder are mixed and stirred at 165℃~175℃ to obtain a mixed filler. Then, the mixed filler is added to SBS modified asphalt and stirred at 165℃~175℃ to obtain acid-etched modified copper slag powder asphalt mortar.

9. The method of using acid-etched modified copper slag powder for use in asphalt mortar according to claim 8, characterized in that... The mass ratio of modified copper slag powder to mineral powder in the mixed filler is 1:3; the mass ratio of the mixed filler to SBS modified asphalt is 1:

1.

10. A method for using acid-etched modified copper slag powder for asphalt mortar according to claim 9, characterized in that... Modified copper slag powder and mineral powder are mixed and stirred at 165℃~175℃ for 120s to obtain a mixed filler. Then, the mixed filler is added to SBS modified asphalt and stirred at 165℃~175℃ for 240s to obtain acid-etched modified copper slag powder asphalt mortar.

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