Preparation process of prestressed hole pressure grouting admixture based on red mud activated copper slag

Abstract

This invention relates to the field of building materials technology, specifically to a preparation process of a prestressed grouting admixture based on red mud activated copper slag. Using 100 parts of dry material as a baseline, the raw material ratio is 75.8 parts cement, 19.0 parts copper slag, 5 parts red mud, 0.2 parts activator, and 20 parts water. The preparation process includes the following steps: S1, raw material fine pretreatment stage; S2, segmented red mud activation stage; S3, gradient mixing preparation stage; S4, finished product stabilization treatment stage. This invention effectively realizes the resource utilization of industrial solid waste. By selecting common industrial wastes such as red mud and copper slag as core raw materials, it reduces the environmental pressure caused by the accumulation of such wastes and lowers the dependence on traditional high-quality raw materials, saving resource costs. Simultaneously, the selection and ratio of raw materials are scientifically matched, and the characteristics of various raw materials and process steps are well-coordinated, avoiding performance defects caused by raw material mismatch and providing a reliable guarantee for the basic application performance of the admixture.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a preparation process of a prestressed duct grouting admixture based on red mud activated copper slag. Background Technology

[0002] Grouting of prestressed ducts is a key process to ensure the integrity and durability of prestressed concrete structures. Its core function is to fill the gap between the prestressed tendons and the ducts, transfer stress, and prevent the prestressed tendons from corroding. Grouting admixtures, as the core component of grouting materials, directly affect the strength, density, and bonding performance of the grout body with the structure. Currently, the grouting admixtures commonly used in the industry are mostly cement-based, combined with traditional mineral admixtures such as fly ash and mineral powder. They rely on high-value raw materials from high-quality natural resources or industrial by-products for a long time, resulting in large resource consumption and high costs. At the same time, red mud and copper slag are large industrial solid wastes generated during the metallurgical and aluminum production process, with huge annual emissions. Long-term open-air accumulation not only occupies a lot of land resources, but may also cause environmental problems such as soil pollution and water pollution due to the leakage of harmful substances. Their resource utilization has become an important issue that the industry urgently needs to solve. In recent years, although some technologies have attempted to introduce industrial solid waste into the field of building materials, there is still much room for improvement in the preparation technology of special admixtures for prestressed duct grouting scenarios. Summary of the Invention

[0003] The purpose of this invention is to provide a preparation process for prestressed duct grouting admixture based on red mud activated copper slag, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a preparation process of prestressed duct grouting admixture based on red mud activated copper slag, with 100 parts of dry material as the basis, and the raw material ratio is 75.8 parts of cement, 19.0 parts of copper slag, 5 parts of red mud, 0.2 parts of activator, and 20 parts of water; The preparation process includes the following steps: S1. Raw material fine pretreatment stage: Copper slag and red mud are ground separately, and the grinding parameters and particle size index of copper slag and red mud are controlled. S2, the segmented red mud activation stage, involves dry mixing the pretreated red mud with the activator, then adding water and stirring at a constant temperature. S3, in the gradient mixing preparation stage, cement and pretreated copper slag are dry-mixed, and then activated red mud slurry is added in batches for mixing. S4. In the finished product stabilization stage, the mixed materials are dried, then screened and sealed for packaging.

[0005] Preferably, the raw material fine pretreatment stage includes: grinding the copper slag using an air jet mill, setting the classifying wheel speed to 18000 r / min, the air pressure to 0.7 MPa, and the grinding time to 25 min, controlling the specific surface area of ​​the copper slag to be 480±20 m². 2 / kg; The red mud was ground using a grid-type ball mill at a speed of 30 r / min for 30 min, and the red mud was controlled to pass through a 200 mesh sieve.

[0006] Preferably, the segmented red mud activation stage includes: adding the pretreated red mud and activator into a vertical low-speed premixing tank, setting the rotation speed to 150 r / min and dry mixing for 5 min; adding water to the dry-mixed material, transferring it to a stainless steel constant temperature stirring vessel, setting the temperature to 65℃ and the rotation speed to 350 r / min and stirring for 40 min.

[0007] Preferably, the gradient mixing preparation stage includes: adding cement and pretreated copper slag into a twin-shaft forced mixer, setting the speed to 100 r / min and dry mixing for 3 min; adding activated red mud slurry to the dry-mixed material in two batches, each batch being half of the total slurry volume, with a 2 min interval between the two additions, and adjusting the speed to 150 r / min and continuing mixing for 6 min.

[0008] Preferably, the finished product stabilization treatment stage includes: spreading the mixed material on a tray with a thickness not exceeding 5cm, placing it in a low-temperature drying oven with a set temperature of 40℃ and a wind speed of 0.8m / s for 1h; sieving the dried material through an 80-mesh vibrating screen, and then sealing it in a woven bag lined with a plastic film.

[0009] Preferably, the raw materials meet the following requirements: the cement is P.O42.5 grade ordinary Portland cement; the copper slag is water-quenched copper slag; the red mud is Bayer process aluminum red mud; the activator is industrial grade flake sodium hydroxide; and the water is tap water or distilled water.

[0010] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention effectively realizes the resource utilization of industrial solid waste. It selects common industrial wastes such as red mud and copper slag as core raw materials, which not only reduces the environmental pressure caused by the accumulation of such wastes, but also reduces the dependence on traditional high-quality raw materials and saves resource costs. At the same time, the selection and proportion of raw materials are scientifically matched, and the characteristics of various raw materials are well matched with the process links, which can avoid performance defects caused by raw material mismatch and provide a reliable guarantee for the basic application performance of the admixture.

[0011] 2. The process design of this invention is both targeted and reasonable. Through the coordinated efforts of refined pretreatment, segmented activation, gradient mixing and stabilization treatment, it can fully stimulate the potential activity of raw materials and effectively avoid problems such as uneven mixing and insufficient reaction, thus ensuring the homogeneity and stability of the admixture. The equipment selection and operating parameters of the entire production process are highly adaptable, the process is highly controllable, and it is easy to promote and apply on a large scale. Moreover, the final product can be well adapted to the construction scenario of prestressed duct grouting, improving the reliability and convenience of construction application. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0014] This invention provides a preparation process for a prestressed duct grouting admixture based on red mud activated copper slag. The raw material ratio is 75.8 parts cement, 19.0 parts copper slag, 5 parts red mud, 0.2 parts activator, and 20 parts water, with 100 parts dry material as the standard. The preparation process includes the following steps: S1. Raw material fine pretreatment stage: Copper slag and red mud are ground separately, and the grinding parameters and particle size index of copper slag and red mud are controlled. S2, the segmented red mud activation stage, involves dry mixing the pretreated red mud with the activator, then adding water and stirring at a constant temperature. S3, in the gradient mixing preparation stage, cement and pretreated copper slag are dry-mixed, and then activated red mud slurry is added in batches for mixing. S4. Finished product stabilization stage: The mixed materials are dried, then screened and sealed for packaging. Specifically, the raw material requirements are as follows: Cement: P・O42.5 grade ordinary Portland cement, which must meet the following requirements: initial setting time ≥45min, final setting time ≤600min, moisture content ≤0.5%, and no dampness or lumps; Copper slag: Water-quenched copper slag, with a total Fe3O4 and SiO2 content of ≥85%, original particle size ≤5mm, moisture content ≤1.0%, and free from impurities such as iron blocks and sand. Red mud: Bayer process aluminum red mud, Al2O3 content ≥15%, CaO content ≥20%, original moisture content ≤30%; Activator: Industrial grade flake sodium hydroxide, purity ≥96%, non-hygroscopic and non-caking, stored in a sealed container; Water: Tap water or distilled water, pH 6-8, suspended solids content ≤5mg / L, free of sulfate and chloride ions; Process Stage Description: The four stages proceed in a logical progression: raw material pretreatment, red mud activation, gradient mixing, and finished product stabilization, ensuring the activation of raw material activity and the homogeneity of the admixture.

[0015] The raw material fine pretreatment stage includes: grinding the copper slag using an air jet mill, setting the classifying wheel speed to 18000 r / min, the air pressure to 0.7 MPa, and the grinding time to 25 min, controlling the specific surface area of ​​the copper slag to be 480±20 m². 2 / kg; The red mud was ground using a grid-type ball mill at a speed of 30 r / min for 30 min, and the red mud was controlled to pass through a 200 mesh sieve; Specifically, the process details are as follows: Copper slag treatment: A QLM-100 air classifier mill was used, equipped with a classifier wheel speed control system (5000~20000 r / min) and an air pressure control system (0.6~0.8 MPa). The classifier wheel speed was set to 18000 r / min and the air pressure to 0.7 MPa. Grinding was carried out for 25 minutes, and the specific surface area of ​​the copper slag was controlled to be 480±20 m². 2 / kg; Red mud treatment: MQG-500×500 type grate ball mill is used, equipped with wear-resistant steel liners and 15~20mm steel balls (filling rate 40%~45%); the rotation speed is set to 30r / min, grinding is performed for 30min, and the red mud is controlled to pass through a 200-mesh sieve (sieve residue ≤5%). Equipment function: QLM-100 airflow mill: Achieves ultrafine copper slag through high-speed airflow impact, enhancing its interfacial bonding activity with cementitious materials; MQG-500×500 type grid ball mill: It breaks down the dense structure of red mud by impacting it with steel balls, exposing more active sites and laying the foundation for subsequent alkali activation; Additional explanation: The core of pretreatment is to refine the raw material particles, control the specific surface area and sieving index, and avoid coarse particles affecting the uniformity of subsequent reactions.

[0016] The segmented red mud activation stage includes: adding the pretreated red mud and activator into a vertical low-speed premixing tank, setting the speed to 150 r / min and dry mixing for 5 min; adding water to the dry-mixed material, transferring it to a stainless steel constant temperature stirring vessel, setting the temperature to 65℃ and the speed to 350 r / min and stirring for 40 min. Specifically, the process details are as follows: Dry mixing treatment: Use NHG-200 vertical low-speed premixing tank, equipped with a paddle agitator (200mm in diameter) with a speed range of 50~300r / min; add 5 parts of pretreated red mud and 0.2 parts of activator, set the speed to 150r / min, and dry mix for 5min; Constant temperature stirring activation: Use HJF-500 stainless steel constant temperature stirring tank, the equipment is equipped with PID temperature control system (temperature control accuracy ±1℃), stainless steel stirring paddle (100~500r / min), tank volume ≥50L; add 20 parts of water to the dry mixed material, set the temperature to 65℃, the speed to 350r / min, and stir for 40min. Equipment function: NHG-200 Vertical Low-Speed ​​Premixing Tank: Prevents activator clumping and achieves preliminary uniform dispersion of red mud and NaOH; HJF-500 stainless steel constant temperature stirring kettle: Through precise temperature control and high-speed stirring, the alkali activation reaction is enhanced, and the dissolution of active oxides such as Al2O3 and SiO2 in red mud is promoted. Additional notes: For segmented activation, dry mixing followed by wet mixing is used to avoid uneven reaction caused by excessively high local concentrations of activator. The amount of water added is set according to water:red mud = 40:1 (20 parts water corresponds to 5 parts red mud).

[0017] The gradient mixing preparation stage includes: adding cement and pretreated copper slag into a twin-shaft forced mixer, setting the speed to 100 r / min and dry mixing for 3 min; adding activated red mud slurry into the dry-mixed material in two batches, each batch being half of the total slurry volume, with a 2 min interval between the two additions, and adjusting the speed to 150 r / min and continuing to mix for 6 min. Specifically, the process details are as follows: Dry mixing: SHJ-1000 twin-shaft forced mixer is used. The equipment is equipped with twin propeller blades (50mm spacing), mixing chamber volume ≥100L, speed 50~200r / min, and discharge butterfly valve with a diameter ≥150mm. 75.8 parts of cement and 19.0 parts of pretreated copper slag are added, the speed is set to 100r / min, and dry mixing is carried out for 3min. Slurry mixing: Add the activated red mud slurry in two batches (total slurry volume 25.2 parts, 12.6 parts each time), with a 2-minute interval between the two batches. Adjust the rotation speed to 150 r / min and continue mixing for 6 minutes. Equipment function: SHJ-1000 Twin-Shaft Forced Mixer: Through the shearing and pushing action of twin propeller blades, it solves the problem of agglomeration of high-content copper slag and slurry, achieves uniform dispersion of dry and wet materials, and ensures the consistency of admixture performance; Additional notes: Gradient mixing involves dry mixing followed by wet mixing, and adding slurry in batches to avoid localized excessive moisture and ensure a uniform and stable mixing system.

[0018] The finished product stabilization process includes: spreading the mixed material on a tray with a thickness not exceeding 5cm, placing it in a low-temperature drying oven at a temperature of 40℃ and a wind speed of 0.8m / s for 1 hour; and then screening the dried material through an 80-mesh vibrating screen and sealing it in woven bags lined with plastic film. Specifically, the process details are as follows: Drying process: A DHG-9070A low-temperature drying oven is used. The equipment is equipped with a forced convection fan (wind speed 0.5~1.0m / s), a temperature control range of room temperature to 200℃ (accuracy ±2℃), an inner chamber volume ≥70L, and a stainless steel drawer tray. The mixed materials are spread on the tray (thickness ≤5cm), the temperature is set to 40℃, the wind speed is 0.8m / s, and the drying time is 1 hour (turning over every 20 minutes). Screening and packaging: Use ZS-515 vibrating screen (80 mesh), the residue after screening is ≤2%; pack the qualified material into woven bags lined with plastic film and seal them. Equipment function: DHG-9070A Low Temperature Drying Oven: Low temperature flexible drying, controlling the moisture content of materials to ≤0.8%, avoiding high temperature damage to the activity of admixtures; ZS-515 vibrating screen: Removes lumps and impurities generated during the drying process, ensuring the homogeneity of the admixture; Additional note: Sealing the packaging after drying can prevent the material from absorbing moisture and extend its shelf life.

[0019] The raw materials meet the following requirements: the cement is P·O42.5 grade ordinary Portland cement; the copper slag is water-quenched copper slag; the red mud is Bayer process aluminum red mud; the activator is industrial grade flake sodium hydroxide; and the water is tap water or distilled water. Specifically, limiting the type of raw materials is the basis for ensuring the performance of admixtures. For example, water-quenched copper slag is selected because its activity is higher than other types of copper slag. The active oxide content of Bayer red mud is more suitable for alkali activation process, and industrial-grade flake sodium hydroxide can ensure stable activation efficiency.

[0020] The method of use and working principle of this invention are as follows: Instructions for use: First, prepare the required cement, copper slag, red mud, activator, and water. Grind and pretreat the copper slag and red mud separately. Then, put the pretreated red mud and activator into the equipment for dry mixing. Add water and stir at a constant temperature to complete the activation. Next, dry mix the cement and pretreated copper slag evenly. Add the activated red mud slurry in batches and continue mixing. Finally, dry and sieve the mixed material, seal and package it, and it can be used for prestressed duct grouting construction.

[0021] Working principle: By grinding and pre-treating copper slag and red mud, the raw material particles are refined and more active sites are exposed, creating conditions for subsequent reactions. The potential gelling active components in the red mud are activated by the alkaline activation effect of the activator and the red mud. A gradient mixing process is adopted to first achieve uniform dispersion among dry materials, and then the slurry is added in batches to avoid uneven local mixing and ensure that cement, copper slag and activated red mud are fully integrated. After drying and screening, impurities and lumps are removed to ensure the homogeneity and stability of the admixture, so that the raw material components can work synergistically in the application of prestressed duct grouting to form a grouting material with stable performance.

[0022] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing prestressed duct grouting admixture based on red mud activated copper slag, characterized in that, Based on 100 parts of dry material, the raw material ratio is 75.8 parts cement, 19.0 parts copper slag, 5 parts red mud, 0.2 parts activator, and 20 parts water; The preparation process includes the following steps: S1. Raw material fine pretreatment stage: Copper slag and red mud are ground separately, and the grinding parameters and particle size index of copper slag and red mud are controlled. S2, the segmented red mud activation stage, involves dry mixing the pretreated red mud with the activator, then adding water and stirring at a constant temperature. S3, in the gradient mixing preparation stage, cement and pretreated copper slag are dry-mixed, and then activated red mud slurry is added in batches for mixing. S4. In the finished product stabilization stage, the mixed materials are dried, then screened and sealed for packaging.

2. The preparation process of prestressed duct grouting admixture based on red mud activated copper slag according to claim 1, characterized in that, The raw material fine pretreatment stage includes: grinding the copper slag using an air jet mill, setting the classifying wheel speed to 18000 r / min, the air pressure to 0.7 MPa, and grinding for 25 min, controlling the specific surface area of ​​the copper slag to be 480±20 m². 2 / kg; The red mud was ground using a grid-type ball mill at a speed of 30 r / min for 30 min, and the red mud was controlled to pass through a 200 mesh sieve.

3. The preparation process of prestressed duct grouting admixture based on red mud activated copper slag according to claim 1, characterized in that, The segmented red mud activation stage includes: adding the pretreated red mud and activator into a vertical low-speed premixing tank, setting the rotation speed to 150 r / min and dry mixing for 5 min; adding water to the dry-mixed material, transferring it to a stainless steel constant temperature stirring vessel, setting the temperature to 65℃ and the rotation speed to 350 r / min and stirring for 40 min.

4. The preparation process of prestressed duct grouting admixture based on red mud activated copper slag according to claim 1, characterized in that, The gradient mixing preparation stage includes: adding cement and pretreated copper slag into a twin-shaft forced mixer, setting the speed to 100 r / min and dry mixing for 3 min; adding activated red mud slurry to the dry-mixed material in two batches, each batch being half of the total slurry volume, with a 2 min interval between the two additions, and adjusting the speed to 150 r / min and continuing mixing for 6 min.

5. The preparation process of prestressed duct grouting admixture based on red mud activated copper slag according to claim 1, characterized in that, The finished product stabilization treatment stage includes: spreading the mixed material on a tray with a thickness not exceeding 5cm, placing it in a low-temperature drying oven with a set temperature of 40℃ and a wind speed of 0.8m / s for 1 hour; sieving the dried material through an 80-mesh vibrating screen, and then sealing it in a woven bag lined with a plastic film.

6. The preparation process of prestressed duct grouting admixture based on red mud activated copper slag according to claim 1, characterized in that, The raw materials meet the following requirements: the cement is P-O42.5 grade ordinary Portland cement; the copper slag is water-quenched copper slag; the red mud is Bayer process aluminum red mud; the activator is industrial grade flake sodium hydroxide; and the water is tap water or distilled water.

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