Tailing sand regulator as well as preparation method and application thereof

Abstract

The invention relates to a tailing sand conditioning agent as well as a preparation method and application thereof, the tailing sand conditioning agent is prepared from the following raw materials: modified biomass charcoal-mineral composite powder, nano silicon dioxide, sodium oleate, sodium thiosulfate, sodium hydroxide, talcum powder, welan gum, a polyether type defoaming agent and deionized water, the preparation method of the modified biomass charcoal-mineral composite powder comprises the following steps: uniformly compounding and mixing pod shell powder, cocklebur fruit powder and montmorillonite powder according to a mass ratio to obtain a mixture, placing the mixture in an acidic activator solution, carrying out dipping treatment, carrying out heat treatment, washing to be neutral, and drying to obtain the modified biomass charcoal-mineral composite powder. The prepared tailing sand conditioning agent is applied to a concrete system containing tailing sand, the compressive strength, chloride ion permeation resistance and freeze-thaw resistance of concrete can be remarkably improved, and the durability is good.

Description

Technical Field

[0001] This invention belongs to the field of concrete additives technology, specifically relating to a tailings sand conditioner, its preparation method, and its application. Background Technology

[0002] Tailings sand differs significantly from natural sand in its physicochemical properties. Tailings sand particles have rough surfaces, are angular, and have high porosity. When tailings sand is incorporated into concrete, these characteristics significantly affect the interfacial structure between cement paste and aggregate, especially in the interfacial transition zone (ITZ). The high adsorption and irregular morphology of tailings sand easily lead to uneven water film thickness, locally high water-cement ratios, numerous microcracks, high porosity, and weak areas with loose structures. The interfacial bond strength in this area is significantly lower than that in natural sand concrete, thus weakening the overall mechanical properties of the concrete. This manifests as a significant decrease in compressive strength, susceptibility to cracking, and poor resistance to chloride ion penetration and freeze-thaw cycles, making it difficult to meet engineering application standards with high compressive strength or durability requirements. Based on these problems, this invention proposes a tailings sand modifier with strong compressive strength, resistance to chloride ion penetration, and freeze-thaw resistance, along with its preparation method and applications. Summary of the Invention

[0003] The purpose of this invention is to provide a tailings sand conditioner, its preparation method, and its application in order to solve the above-mentioned problems.

[0004] The present invention achieves the above objectives through the following technical solutions: A tailings sand conditioner, wherein the raw materials for preparing the tailings sand conditioner, by weight, include 30-40 parts of modified biochar-mineral composite powder, 7-12 parts of nano silica, 8-15 parts of sodium oleate, 5-12 parts of sodium thiosulfate, 3-8 parts of sodium hydroxide, 3-8 parts of talc, 0.5-2 parts of acetone, 1-3 parts of polyether defoamer, and 20-35 parts of deionized water; The modified biochar-mineral composite powder is obtained by mixing bean pod shell powder, cocklebur powder and montmorillonite powder in a certain mass ratio, placing the mixture in an acidic activator solution for impregnation, followed by heat treatment, washing to neutral and drying.

[0005] As a further optimization of the present invention, the mass ratio of the bean pod outer shell powder, cocklebur powder, and montmorillonite powder is (2-6):(1-5):1.

[0006] As a further optimization of the present invention, the method for obtaining the mixture is to prepare the bean pod outer shell powder, cocklebur powder and montmorillonite powder according to the mass ratio, stir at a speed of 600-800 r / min for 30-45 min, and then obtain the mixture after ultrasonic dispersion treatment. Alternatively, montmorillonite powder and deionized water can be mixed in a mass ratio of 1:3-5 to form a suspension. Then, bean pod shell powder and cocklebur powder can be mixed in the same mass ratio and stirred at a speed of 600-800 r / min for 30-45 min. During the stirring process, the suspension can be sprayed into the mixture of bean pod shell powder and cocklebur powder. The mixture can then be obtained after ultrasonic dispersion.

[0007] As a further optimization of the present invention, the impregnation treatment specifically involves using an acidic activator solution with a mass concentration of 20-32% to perform an impregnation treatment for 3-5 hours at a temperature of 30-38°C.

[0008] As a further optimization of the present invention, the acidic activator solution is an H2SO4 solution, an HNO3 solution, or an H3PO4 solution.

[0009] As a further optimization of the present invention, the heat treatment specifically involves performing heat treatment at a temperature of 500-650°C for 5-8 hours under nitrogen atmosphere protection.

[0010] This invention also provides a method for preparing a tailings sand conditioner, comprising dissolving sodium hydroxide, sodium thiosulfate, and sodium oleate sequentially in deionized water, then adding modified biochar-mineral composite powder and nano-silica, maintaining the temperature at 30-40°C, stirring and mixing at 400-500 r / min for 30-45 min, adding talc powder and warm wheel adhesive, stirring and mixing at 200-300 r / min for 30-40 min, adding polyether-type defoamer, stirring and mixing at 100-200 r / min for 15-20 min, and aging at room temperature for 18-24 h.

[0011] The present invention also provides an application of tailings sand regulator in concrete, wherein the amount of tailings sand regulator added to the tailings sand concrete system is 5-20% of the amount of tailings sand.

[0012] The beneficial effects of this invention are as follows: 1) The tailings sand conditioner prepared by this invention can significantly improve the compressive strength, chloride ion penetration resistance, freeze-thaw resistance and durability of concrete when applied to concrete systems containing tailings sand. 2) In the preparation of modified biochar-mineral composite powder, this invention uses H3PO4 solution to activate bean pod shell powder, cocklebur powder, and montmorillonite powder before heat treatment. This synergistic effect significantly improves the compressive strength, chloride ion penetration resistance, and freeze-thaw resistance of concrete. 3) In the preparation of modified biochar-mineral composite powder, this invention prepares montmorillonite powder as a suspension and sprays it onto the ultrasonically treated mixture of bean pod shell powder and cocklebur powder. This method yields better results than directly mixing the montmorillonite powder, bean pod shell powder, and cocklebur powder. Detailed Implementation

[0013] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0014] I. Materials 1. Bean pod shell powder: In this invention, soybean ( Glycine max (L.) Merr. The powder obtained by crushing the seeded and shelled pods; passed through a 20-mesh sieve; 2. Wheat straw powder: In this invention, wheat ( Triticum aestivum L. The powder obtained by crushing straw is passed through a 20-mesh sieve; 3. Xanthium sibiricum powder: In this invention, Xanthium sibiricum (… Xanthium L. The powder obtained by crushing mature fruits of plants with involucre; passed through a 20-mesh sieve; 4. Montmorillonite powder: purchased from Nantong Runfeng Petrochemical Co., Ltd., brand: Runfeng, CAS No.: 1318-93-0; passed through an 80-mesh sieve; 5. Palaequa calcite powder (also known as attapulgite powder): purchased from Shanghai Mairui Biochemical Technology Co., Ltd., brand: Mairui, CAS No.: 12174-11-7; passed through an 80-mesh sieve; 6. Tailings: Iron tailings purchased from Fanshi County, Xinzhou City, Shanxi Province; 7. Polyether-type defoamer: purchased from Hubei Chengfeng Chemical Co., Ltd., purity 99%; Unless otherwise specified, the methods used in this embodiment are conventional methods known to those skilled in the art, and the reagents and materials used are commercially available products.

[0015] II. Methods Example 1 In this embodiment, a raw material for preparing a tailings sand conditioner is provided, which, by weight, includes 30 parts of modified biochar-mineral composite powder, 12 parts of nano silica, 8 parts of sodium oleate, 10 parts of sodium thiosulfate, 8 parts of sodium hydroxide, 3 parts of talc, 0.5 parts of warm wheel adhesive, 1 part of polyether defoamer, and 27.5 parts of deionized water.

[0016] The preparation method of this tailings sand conditioner includes the following specific steps: Step 1: Mix the bean pod outer shell powder, cocklebur powder, and montmorillonite powder in a mass ratio of 6:3:1, stir at 750 r / min for 40 min, and then disperse by ultrasonication to obtain the mixture. Step 2: The mixture was impregnated with a 24% H2SO4 solution at 35°C for 4 hours. After dehydration and drying, it was heat-treated at 620°C for 6.5 hours under nitrogen atmosphere. After cooling to room temperature, it was washed until neutral and dried to obtain modified biochar-mineral composite powder. Step 3: Dissolve sodium hydroxide, sodium thiosulfate, and sodium oleate in deionized water in sequence. Then add modified biochar-mineral composite powder and nano silica. Maintain the temperature at 37±2℃ and stir at 480 r / min for 40 min. Add talc powder and warm wheel adhesive and stir at 260 r / min for 32 min. Add polyether defoamer and stir at 150 r / min for 18 min. After aging at room temperature for 20 h, tailings sand conditioner is obtained.

[0017] Example 2 In this embodiment, a raw material for preparing a tailings sand conditioner is provided, which, by weight, includes 36 parts of modified biochar-mineral composite powder, 9 parts of nano silica, 13 parts of sodium oleate, 7 parts of sodium thiosulfate, 5 parts of sodium hydroxide, 4 parts of talc, 0.8 parts of warm wheel adhesive, 1.2 parts of polyether defoamer, and 24 parts of deionized water. The specific preparation methods are consistent with those in Example 1.

[0018] Example 3 In this embodiment, a raw material for preparing a tailings sand conditioner is provided, which, by weight, includes 40 parts of modified biochar-mineral composite powder, 7 parts of nano silica, 10 parts of sodium oleate, 5 parts of sodium thiosulfate, 3 parts of sodium hydroxide, 8 parts of talc, 1.2 parts of warm wheel adhesive, 1.5 parts of polyether defoamer, and 24.3 parts of deionized water. The specific preparation methods are consistent with those in Example 1.

[0019] Example 4 In this embodiment, a raw material for preparing a tailings sand conditioner is provided, which, by weight, includes 36 parts of modified biochar-mineral composite powder, 9 parts of nano silica, 13 parts of sodium oleate, 7 parts of sodium thiosulfate, 5 parts of sodium hydroxide, 4 parts of talc, 0.8 parts of warm wheel adhesive, 1.2 parts of polyether defoamer, and 24 parts of deionized water.

[0020] The preparation method of this tailings sand conditioner includes the following specific steps: Step 1: Prepare a suspension by mixing montmorillonite powder and deionized water at a mass ratio of 1:4.5. Then, prepare a mixture of bean pod shell powder and cocklebur powder at a mass ratio of 6:3:1. Stir the mixture at 750 r / min for 40 min. During the stirring process, spray the suspension into the mixture of bean pod shell powder and cocklebur powder. After ultrasonic dispersion, obtain the final mixture. Step 2: The mixture was impregnated with a 24% H2SO4 solution at 35°C for 4 hours. After dehydration and drying, it was heat-treated at 620°C for 6.5 hours under nitrogen atmosphere. After cooling to room temperature, it was washed until neutral and dried to obtain modified biochar-mineral composite powder. Step 3: Dissolve sodium hydroxide, sodium thiosulfate, and sodium oleate in deionized water in sequence. Then add modified biochar-mineral composite powder and nano silica. Maintain the temperature at 37±2℃ and stir at 480 r / min for 40 min. Add talc powder and warm wheel glue and stir at 260 r / min for 32 min. Add polyether defoamer and stir at 150 r / min for 18 min. After aging at room temperature for 20 h, tailings sand conditioner is obtained.

[0021] Example 5 In this embodiment, based on Example 4, step 2 of the preparation method of tailings sand conditioner was adjusted. The adjusted step 2 is as follows: using a 24% HNO3 solution, impregnate at 35°C for 4 hours, dehydrate and dry, then heat-treat at 620°C for 6.5 hours under nitrogen atmosphere protection, cool to room temperature, wash to neutral and dry to obtain modified biochar-mineral composite powder. Everything else is the same as in Example 4.

[0022] Example 6 In this embodiment, based on Example 4, step 2 of the preparation method of tailings sand conditioner was adjusted. The adjusted step 2 is as follows: using a 24% H3PO4 solution, impregnate at 35°C for 4 hours, dehydrate and dry, then heat-treat at 620°C for 6.5 hours under nitrogen atmosphere protection, cool to room temperature, wash to neutral and dry to obtain modified biochar-mineral composite powder. Everything else is the same as in Example 4.

[0023] Comparative Example 1 In this comparative example, the preparation method of the tailings sand conditioner was adjusted based on Example 6, and the adjusted method is as follows: Step 1: Mix the bean pod outer shell powder and cocklebur powder according to the mass ratio, stir at 750 r / min for 40 min, and then disperse by ultrasonication to obtain a mixture; Step 2: Using a 24% (w / w) H3PO4 solution, the mixture and montmorillonite powder were impregnated separately at 35°C for 4 hours. After dehydration and drying, the impregnated mixture and montmorillonite powder were heat-treated separately at 620°C for 6.5 hours under nitrogen atmosphere. After cooling to room temperature, they were washed until neutral and dried to obtain modified biochar and modified montmorillonite powder, respectively. The modified biochar and modified montmorillonite powder were then mixed to obtain the modified mixed powder. The mass ratio of bean pod shell powder, cocklebur powder, and montmorillonite powder is 6:3:1. Step 3: Dissolve sodium hydroxide, sodium thiosulfate, and sodium oleate in deionized water in sequence. Then add the modified mixed powder and nano silica. Maintain the temperature at 37±2℃ and stir at 480 r / min for 40 min. Add talc powder and warm wheel glue and stir at 260 r / min for 32 min. Add polyether defoamer and stir at 150 r / min for 18 min. After aging at room temperature for 20 h, the tailings sand conditioner is obtained.

[0024] Comparative Example 2 In this comparative example, based on Example 6, step 1 of the preparation method of tailings sand conditioner was adjusted. The adjusted step 1 is as follows: Paphragmites powder and deionized water are mixed in a mass ratio of 1:4.5 to form a suspension. Then, pod shell powder and cocklebur powder are mixed in a mass ratio of 6:3:1. The mixture is stirred at 750 r / min for 40 min. During the stirring process, the suspension is sprayed into the mixture of pod shell powder and cocklebur powder. The mixture is then obtained after ultrasonic dispersion treatment. Everything else is consistent with Example 6.

[0025] Comparative Example 3 In this comparative example, based on Example 6, step 1 of the preparation method of tailings sand conditioner was adjusted. The adjusted step 1 is as follows: Montmorillonite powder and deionized water are mixed in a mass ratio of 1:4.5 to form a suspension, and then bean pod shell powder is mixed in a mass ratio (the mass ratio of bean pod shell powder to montmorillonite powder is 9:1). The mixture is stirred at a speed of 750 r / min for 40 min. During the stirring process, the suspension is sprayed into the bean pod shell powder, and then the mixture is obtained after ultrasonic dispersion treatment. Everything else is consistent with Example 6.

[0026] Comparative Example 4 In this comparative example, based on Example 6, step 1 of the preparation method of tailings sand conditioner was adjusted. The adjusted step 1 is as follows: Montmorillonite powder and deionized water are mixed in a mass ratio of 1:4.5 to form a suspension, and wheat straw powder is mixed in a mass ratio of 9:1 (wheat straw powder to montmorillonite powder). The mixture is stirred at 750 r / min for 40 min. During the stirring process, the suspension is sprayed into the wheat straw powder, and then the mixture is obtained after ultrasonic dispersion. Everything else is consistent with Example 6.

[0027] Blank group In this blank group, a raw material for preparing a tailings sand conditioner is provided, which, by weight, includes 9 parts of nano-silica, 13 parts of sodium oleate, 7 parts of sodium thiosulfate, 5 parts of sodium hydroxide, 4 parts of talc, 0.8 parts of warm wheel adhesive, 1.2 parts of polyether defoamer, and 24 parts of deionized water. The tailings sand conditioner is prepared by dissolving sodium hydroxide, sodium thiosulfate, and sodium oleate in deionized water in sequence, then adding nano-silica, maintaining the temperature at 37±2℃, stirring and mixing at 480 r / min for 40 min, adding talc powder and warm wheel glue, stirring and mixing at 260 r / min for 32 min, adding polyether defoamer, stirring and mixing at 150 r / min for 18 min, and aging at room temperature for 20 h to obtain the tailings sand conditioner.

[0028] III. Experimental Testing The concrete mix composition used in this experiment is shown in Table 1 (unit: kg / m³). 3 ): Table 1. Concrete system mix design ; The concrete system used in this invention includes cementitious materials (P·S·A32.5 slag silicate cement, fly ash and slag powder), aggregates (gravel and tailings sand, sand, wherein the particle size of gravel is 5-10mm, the particle size of tailings sand and sand is 0.5-1mm, and the gradation ratio of coarse aggregate to fine aggregate is (1-1.8):(1-1.5)) and water, with a binder-to-water ratio of 1.5-2.7:1; The tailings sand modifier is added to the above-mentioned concrete system at a dosage of 5-20% of the tailings sand dosage; in this invention, while keeping the other component proportions unchanged, the tailings sand modifier in Examples 1-6, Comparative Examples 1-4, and the blank group is added at 9.7% of the tailings sand dosage (i.e., the dosage is 61.9 kg / m³). 3 ); (1) Compressive strength test: The 7-day and 28-day compressive strength of concrete specimens from Examples 1-6, Comparative Examples 1-4, and the blank group were tested using a GHT450 rebound hammer. The test results are shown in Table 2. Table 2 Compressive Strength Test Data Recording Table ; Experimental Conclusions: Based on the data in Table 2, it can be seen that the tailings sand conditioner prepared in this embodiment of the invention, when applied to concrete systems containing tailings sand, can significantly improve the compressive strength of concrete. The modified biochar-mineral composite powder is the main component. The core technologies in preparing the modified biochar-mineral composite powder are the specific acidic activator used and the heat treatment process of mixing specific biomass and mineral powders together. This invention experimentally verifies that activating bean pod shell powder, cocklebur powder, and montmorillonite powder with H3PO4 solution followed by heat treatment significantly improves the compressive strength of concrete under their synergistic effect. Furthermore, in the preparation of the modified biochar-mineral composite powder, spraying a suspension of montmorillonite powder onto the ultrasonically treated mixture of bean pod shell powder and cocklebur powder yields better results than directly mixing the montmorillonite powder, bean pod shell powder, and cocklebur powder.

[0029] (2) Chloride ion penetration resistance test: Concrete specimens from Examples 1-6, Comparative Examples 1-4, and the blank group were tested according to the test methods in GB / T 50082-2009 Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete. The classification standards for chloride ion penetration resistance are shown in Table 3, and the test results are shown in Table 4. Table 3 Classification Standards for Chloride Ion Penetration Resistance ; (3) Freeze-thaw resistance test: The test was conducted according to the test method (rapid freezing method) of GB / T 50082-2009 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete. The concrete specimens of Examples 1-6, Comparative Examples 1-4 and the blank group were tested. The test results are shown in Table 4. The specific results are as follows: Table 4 Record Table of Chloride Ion Penetration Resistance and Freeze-Thaw Resistance Test Data ; Experimental Conclusion: Based on the data analysis in Table 4, the tailings sand conditioner prepared in Examples 1-6 of this invention, when applied to concrete systems containing tailings sand, can significantly enhance the concrete system's resistance to chloride ion penetration and freeze-thaw resistance. Example 6 is the optimal embodiment, demonstrating good durability, long-term stability, and a long service life. The above embodiments only illustrate several implementation methods of this invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this invention, and these all fall within the protection scope of this invention.

Claims

1. A tailings sand conditioner, characterized in that: The raw materials for preparing the tailings sand conditioner, by weight, include 30-40 parts of modified biochar-mineral composite powder, 7-12 parts of nano silica, 8-15 parts of sodium oleate, 5-12 parts of sodium thiosulfate, 3-8 parts of sodium hydroxide, 3-8 parts of talc, 0.5-2 parts of warm wheel adhesive, 1-3 parts of polyether defoamer, and 20-35 parts of deionized water. The modified biochar-mineral composite powder is obtained by mixing bean pod shell powder, cocklebur powder and montmorillonite powder in a certain mass ratio, placing the mixture in an acidic activator solution for impregnation, followed by heat treatment, washing to neutral and drying.

2. The tailings sand conditioner according to claim 1, characterized in that: The mass ratio of the bean pod outer shell powder, cocklebur powder, and montmorillonite powder is (2-6):(1-5):

1.

3. The tailings sand conditioner according to claim 1, characterized in that: The method for obtaining the mixture is as follows: the pod shell powder, cocklebur powder, and montmorillonite powder are mixed in a mass ratio, stirred at a speed of 600-800 r / min for 30-45 min, and then ultrasonically dispersed to obtain the mixture. Alternatively, montmorillonite powder and deionized water can be mixed in a mass ratio of 1:3-5 to form a suspension. Then, bean pod shell powder and cocklebur powder can be mixed in the same mass ratio and stirred at a speed of 600-800 r / min for 30-45 min. During the stirring process, the suspension can be sprayed into the mixture of bean pod shell powder and cocklebur powder. The mixture can then be obtained after ultrasonic dispersion.

4. The tailings sand conditioner according to claim 1, characterized in that: The impregnation treatment specifically involves using an acidic activator solution with a mass concentration of 20-32% to impregnate for 3-5 hours at a temperature of 30-38°C.

5. The tailings sand conditioner according to claim 4, characterized in that: The acidic activator solution is an H2SO4 solution, an HNO3 solution, or an H3PO4 solution.

6. The tailings sand conditioner according to claim 1, characterized in that: The heat treatment specifically involves performing heat treatment at a temperature of 500-650℃ for 5-8 hours under a nitrogen atmosphere.

7. A method for preparing a tailings sand conditioner as described in any one of claims 1-6, characterized in that: Sodium hydroxide, sodium thiosulfate, and sodium oleate were dissolved in deionized water in sequence. Modified biochar-mineral composite powder and nano-silica were then added. The mixture was stirred at 400-500 rpm for 30-45 minutes at 30-40°C. Talc and warm wheel adhesive were then added and stirred at 200-300 rpm for 30-40 minutes. Polyether defoamer was then added and stirred at 100-200 rpm for 15-20 minutes. The mixture was then aged at room temperature for 18-24 hours.

8. The application of a tailings sand modifier as described in any one of claims 1-6 in concrete, characterized in that: The amount of tailings sand modifier added to the tailings sand concrete system is 5-20% of the amount of tailings sand.