Method for preparing pozzolanic admixture through manganese slag modification

Abstract

The invention relates to the technical field of materials, in particular to a method for preparing a pozzolanic admixture through manganese slag modification, which comprises the following steps: homogenizing manganese slag, lithium slag, shale or clay and carbon powder in a brick and tile kiln through mechanical mixing equipment, feeding the mixture into a crusher for crushing, preparing a green brick by using forming equipment, and then feeding into a drying kiln for drying, thereby obtaining the pozzolanic admixture. And transferring into a high-temperature kiln for calcining, taking out the bricks from the kiln, cooling, and crushing to obtain the volcanic ash mixed material. Manganese slag, lithium slag and shale or clay are combined, carbon powder is introduced to serve as internal fuel, the manganese slag is subjected to high-temperature calcination modification through an existing brick and tile kiln after homogenization, crushing, green brick preparation and drying, a new production line is not needed, cost is reduced, the pozzolanic mixed material is obtained, and the physical and chemical properties of the pozzolanic mixed material are remarkably improved; the performance of the modified manganese slag meets the new standard requirement, the carbon powder plays a role of internal fuel, the calcined material is good in activity and high in silicon and aluminum content, and the performance of the calcined manganese slag is further improved.

Description

Technical Field

[0001] The invention relates to the field of material technology, and in particular to a method for preparing a volcanic ash mixed material by modifying manganese slag. Background Art

[0002] Manganese slag is the waste residue of sulfuric acid leaching and filter pressing generated in the process of producing electrolytic manganese and electrolytic manganese dioxide, or the smelting manganese slag during the smelting of ferromanganese. It contains a variety of valuable components and can be converted into industrial products through resource utilization. Since manganese slag contains active ingredients such as silicon dioxide, aluminum oxide, manganese oxide, and has good fineness and activity, it can give full play to its micro-aggregate effect and filling function in cement. Therefore, manganese slag is usually modified and used as an admixture in cement production.

[0003] Due to the implementation of the new national cement standard GB175-2023 "General Portland Cement", it is clearly stipulated that only granulated blast furnace slag / slag powder, fly ash, pozzolanic mixed materials, limestone and sandstone can be used as general Portland cement admixtures, and manganese slag modified by traditional methods cannot meet the requirements. Therefore, the present invention provides a method for preparing pozzolanic admixtures by modifying manganese slag. After high-temperature calcination modification treatment of manganese slag in a brick kiln, it can meet the standard requirements of GB / T2847-2022 "Pozzolanic Mixtures for Cement" and meet the use conditions of the new national standard for cement. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing pozzolanic mixed materials by modifying manganese slag.

[0005] A method for preparing a pozzolanic mixed material by modifying manganese slag, comprising the following steps:

[0006] (1) Batching and homogenization: in a brick kiln, manganese slag, lithium slag, shale or clay, and carbon powder are accurately weighed in a mass ratio of 35-42:28-33:23-28:3-5, and the total ratio of each material is 100, and then fully homogenized by a mechanical mixing device;

[0007] (2) Crushing and forming: The homogenized mixture is sent to a crusher for crushing, and then the crushed material is pressed or extruded into a brick by a forming device;

[0008] (3) Drying and calcining: The formed bricks are sent to a drying kiln and dried at 150-200°C for 80-100 min. Then they are immediately placed in a high-temperature kiln with a heating rate of 10-20°C / min and calcined at 850-950°C for 80-100 min.

[0009] (4) Cooling and crushing: After calcination, the bricks are taken out of the high-temperature kiln and cooled to room temperature. They are then crushed into particles with a size of ≤3.5 cm using a crusher to produce the pozzolanic admixture used in cement production.

[0010] The lithium slag is a by-product of the process of producing lithium batteries in new energy battery factories; the carbon powder is waste slag generated in the process of producing lithium batteries in new energy battery factories, and its calorific value is 7000kcal / kg.

[0011] The silicate minerals in raw materials such as manganese slag and lithium slag that have been calcined at high temperatures undergo phase changes to form highly active amorphous phases. These phases can react with calcium hydroxide during cement hydration to produce gelling calcium silicate hydrate and calcium aluminate hydrate, significantly improving the volcanic ash activity of the admixture.

[0012] The prepared volcanic ash admixture is used in cement production. As a cement admixture, it can improve the hydration performance of cement and significantly improve the strength, durability and working performance of cement. At the same time, due to the addition of industrial waste, the cost of cement production can be reduced, which meets the requirements of green building and sustainable development. In addition, the volcanic ash admixture is ground into a composite admixture for concrete.

[0013] Preferably, in the batching and homogenizing steps, the mass ratio of the manganese slag, lithium slag, shale or clay, and carbon powder is 40:30:26:4.

[0014] Preferably, in the crushing and shaping step, the homogenized mixture is crushed to a particle size ranging from 0.074 to 2 mm.

[0015] Preferably, in the crushing and forming steps, the forming technology is used to make the brick density reach 2.0-2.5g / cm 2 .

[0016] Preferably, in the crushing and forming steps, the size of the brick is 240×115×53 mm or other specifications.

[0017] Preferably, in the drying and calcining steps, the bricks are preheated before drying, that is, kept at 80-100° C. for 30-60 minutes.

[0018] Preferably, during the drying and calcining steps, the atmosphere in the high-temperature kiln is adjusted to a slightly oxidizing environment.

[0019] Preferably, in the cooling and crushing steps, the cooling process adopts a slow cooling method, including natural air cooling or controlling the cooling rate.

[0020] Preferably, the shale or clay is replaced by an equal amount of fly ash or other siliceous and aluminous mineral raw materials.

[0021] Preferably, when the pozzolanic admixture is used in cement production, its dosage is 20-40% of the total mass of cement.

[0022] The beneficial effects achieved by the present invention are:

[0023] 1. The present invention combines manganese slag and lithium slag with shale or clay, and introduces carbon powder as internal fuel. After homogenization, crushing, making into bricks, and drying, the product is calcined and modified at high temperature in a brick kiln to obtain a product, i.e., a volcanic ash mixed material, so that its physical and chemical properties are significantly improved, and the performance of the manganese slag after calcination and modification meets the requirements of the new standard. Since the carbon powder acts as an internal fuel, the activity of the calcined material is good, and the silicon and aluminum contents are relatively high, thereby further improving the performance of the calcined manganese slag.

[0024] 2. The present invention utilizes the existing brick kiln to carry out manganese slag modification treatment, and there is no need to build a special modification production line, which greatly reduces the initial investment cost and construction period; the calcination technology and equipment of the brick kiln have certain commonalities with the manganese slag modification treatment, and the modification requirements can be met by adjusting the process parameters and operating procedures, which is convenient for flexible adjustment of production according to market demand and raw material supply; combining the manganese slag modification treatment with the brick kiln production is also an attempt to the traditional building materials industry and an exploration of industrial upgrading and transformation.

[0025] 3. The present invention utilizes a variety of industrial wastes and natural materials as raw materials, which not only realizes the resource utilization of industrial wastes, reduces environmental pollution, and promotes the development of a circular economy, but also the use of carbon powder as an internal fuel can reduce the consumption of external energy and further reduce production costs. The carbon powder produced by a new energy battery factory is used as an auxiliary fuel, which has a high calorific value and helps to improve the energy efficiency of brick kilns.

[0026] 4. The volcanic ash admixture produced by the present invention has higher activity, so that the cement products have better mechanical properties and durability.

[0027] 5. By adjusting the raw material ratio and production process, the volcanic ash mixed material produced by the present invention can be applied to various types of cement, including ordinary Portland cement, composite Portland cement, volcanic Portland cement, etc., thereby expanding the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a schematic flow chart of the method for preparing pozzolanic mixed materials by modifying manganese slag adopted in the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with specific embodiments.

[0030] 500t of manganese slag from a manganese company was selected. The lithium slag is a by-product of the production of lithium batteries in new energy battery factories; the carbon powder is the waste slag produced in the production of lithium batteries in new energy battery factories, and its calorific value is 7000kcal / kg.

[0031] Table 1 Composition data of manganese slag, shale and clay used in the examples

[0032]

[0033] Table 2 Raw materials and ingredients list of Example 1-Example 3

[0034]

[0035]

[0036] Example 1: A method for preparing a pozzolanic mixed material by modifying manganese slag, such as Figure 1 As shown, the following steps are included:

[0037] (1) Batching and homogenization: in a brick kiln, manganese slag, lithium slag, shale and carbon powder are accurately weighed in a mass ratio of 40:30:26:4, with 150 t of manganese slag used, and fully homogenized by a horizontal mixer;

[0038] (2) Crushing and molding: The homogenized mixture is sent to a crusher for crushing to a particle size of 1 mm. A mechanical molding machine is then used to mold the crushed material into bricks with a size of 240 × 115 × 53 mm. The molding technology is used to make the density of the bricks reach 2.2 g / cm 2 .

[0039] (3) Drying and calcining: The formed bricks are sent to the drying kiln and preheated before drying, that is, kept at 90°C for 45 minutes, and then dried at 180°C for 90 minutes. Then they are immediately placed in a high-temperature kiln and calcined at 900°C for 90 minutes. The heating rate is 15°C / min, and the atmosphere in the high-temperature kiln is adjusted to a slightly oxidizing environment.

[0040] (4) Cooling and crushing: After calcination, the bricks are taken out of the high-temperature kiln and cooled to room temperature. Natural air cooling is used in the cooling process. They are then crushed into particles with a particle size of 1.2 cm using a crusher, thus obtaining a volcanic ash admixture for cement production with a mass of 265.5 tons.

[0041] Example 2: A method for preparing a pozzolanic mixed material by modifying manganese slag, such as Figure 1 As shown, the following steps are included:

[0042] (1) Batching and homogenization: in a brick kiln, manganese slag, lithium slag, clay and carbon powder were accurately weighed in a mass ratio of 37:32:28:3, with 150 t of manganese slag used, and fully homogenized by a horizontal mixer;

[0043] (2) Crushing and molding: The homogenized mixture is sent to a crusher for crushing to a particle size of 1.5 mm. The crushed material is then extruded into a brick with a size of 240 × 115 × 53 mm. The density of the brick reaches 2.0 g / cm by molding technology. 2 .

[0044] (3) Drying and calcining: The formed bricks are sent to the drying kiln and preheated before drying, that is, kept at 80°C for 60 minutes, and then dried at 160°C for 100 minutes. Then they are immediately placed in a high-temperature kiln and calcined at 850°C for 100 minutes. The heating rate is 12°C / min, and the atmosphere in the high-temperature kiln is adjusted to a slightly oxidizing environment.

[0045] (4) Cooling and crushing: After calcination, the bricks were taken out of the high-temperature kiln and cooled to room temperature. The cooling rate was controlled at 10 °C / min. The bricks were then crushed into particles with a diameter of 2.5 cm using a crusher. The pozzolanic admixture used in cement production was obtained, with a mass of 306.2 t.

[0046] Example 3: A method for preparing a volcanic ash mixed material by modifying manganese slag, such as Figure 1 As shown, the following steps are included:

[0047] (1) Batching and homogenization: in a brick kiln, manganese slag, lithium slag, fly ash and carbon powder are accurately weighed in a mass ratio of 42:28:25:5, with 150 t of manganese slag used, and fully homogenized by a horizontal mixer;

[0048] (2) Crushing and molding: The homogenized mixture is sent to a crusher for crushing to a particle size of 2 mm. A hydraulic press is then used to make bricks with a size of 240 × 115 × 53 mm. The density of the bricks reaches 2.5 g / cm by molding technology. 2 .

[0049] (3) Drying and calcining: The formed bricks are sent to the drying kiln and preheated before drying, that is, kept at 100°C for 30 minutes, and then dried at 200°C for 80 minutes. Then they are immediately placed in a high-temperature kiln and calcined at 950°C for 80 minutes. The heating rate is 20°C / min, and the atmosphere in the high-temperature kiln is adjusted to a slightly oxidizing environment.

[0050] (4) Cooling and crushing: After calcination, the bricks are taken out of the high-temperature kiln and cooled to room temperature. Natural air cooling is used in the cooling process. They are then crushed into particles with a particle size of 3.3 cm using a crusher, thus obtaining a volcanic ash admixture for cement production with a mass of 241.5 tons.

[0051] Comparative Example: Using conventional low-temperature modified manganese slag to prepare a volcanic ash mixed material, specifically comprising the following steps:

[0052] Manganese slag, clay and coal gangue are accurately weighed in a mass ratio of 70:26:4, with the moisture content of coal gangue ≤8% and the amount of manganese slag 50t, and are fully homogenized by a horizontal mixer; the homogenized mixture is sent to a crusher for crushing to a particle size of 1mm; then it is dried at 180℃ for 90min, and then calcined at 500℃ for 90min; after calcination, the air is removed and naturally cooled to room temperature to obtain a volcanic ash mixture with a mass of 65.4t.

[0053] Test Example: According to the performance indicators of the pozzolanic mixed materials obtained in Example 1, Example 2, Example 3, and the comparative example, physical and chemical tests were carried out in accordance with the technical requirements of GB / T2847-2022 "Pozzolanic mixed materials for cement";

[0054] Table 3 Technical requirements of GB / T2847-2022 "Pozzolanic mixed materials used in cement"

[0055]

[0056] Table 4 Performance indexes of volcanic ash mixed materials in embodiments and comparative examples

[0057]

[0058]

[0059] It can be seen from Table 4 that the various performance indicators of the pozzolanic mixed materials produced according to Examples 1 to 3 can meet the technical requirements of GB / T2847-2022 "Pozzolanic mixed materials for cement", and meet the use conditions of the new national standard for cement;

[0060] The volcanic ash mixed material prepared in Example 1 was selected to be tested for heavy metal content. As can be seen from Table 5, the test results of the leachable heavy metal content meet the standard requirements.

[0061] Table 5 Heavy metal content leached from Example 1

[0062]

[0063]

[0064] The volcanic ash admixture obtained by the present invention is directly sent to a cement plant to replace traditional cement admixtures to produce 42.5-grade ordinary Portland cement, with the admixture amount being 6-20% of the total mass of cement. The volcanic ash admixture is superior to traditional cement admixtures.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing pozzolanic mixed materials by modifying manganese slag, characterized in that: The following steps are involved: (1) Batching and homogenization: in a brick kiln, manganese slag, lithium slag, shale or clay, and carbon powder are accurately weighed in a mass ratio of 35-42:28-33:23-28:3-5, and the total ratio of each material is 100, and then fully homogenized by a mechanical mixing device; (2) Crushing and forming: The homogenized mixture is sent to a crusher for crushing, and then the crushed material is pressed or extruded into a brick by a forming device; (3) Drying and calcining: The formed bricks are sent to a drying kiln and dried at 150-200°C for 80-100 min. Then they are immediately placed in a high-temperature kiln with a heating rate of 10-20°C / min and calcined at 850-950°C for 80-100 min. (4) Cooling and crushing: After calcination, the bricks are taken out of the high-temperature kiln and cooled to room temperature, and then crushed into particles with a particle size of ≤3.5 cm using a crusher, thus obtaining the pozzolanic admixture used in cement production; The lithium slag is a by-product of the process of producing lithium batteries in new energy battery factories; the carbon powder is waste slag generated in the process of producing lithium batteries in new energy battery factories, and its calorific value is 7000kcal / kg.

2. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the batching and homogenizing steps, the mass ratio of the manganese slag, lithium slag, shale or clay, and carbon powder is 40:30:26:

4.

3. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the crushing and shaping step, the homogenized mixture is crushed to a particle size range of 0.074-2 mm.

4. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the crushing and molding steps, the molding technology is used to make the brick density reach 2.0-2.5g / cm 2 .

5. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the crushing and forming steps, the size of the brick is 240×115×53 mm or other standard specifications.

6. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the drying and calcining steps, the bricks are preheated before drying, that is, kept at 80-100°C for 30-60 minutes.

7. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: During the drying and calcining steps, the atmosphere in the high temperature kiln is adjusted to a slightly oxidizing environment.

8. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: In the cooling and crushing steps, the cooling process adopts a slow cooling method, including natural air cooling or controlling the cooling rate.

9. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: The shale or clay is replaced by an equal amount of fly ash or other silica-alumina mineral raw materials.

10. The method for preparing pozzolanic mixed materials by modifying manganese slag according to claim 1, characterized in that: When the pozzolanic admixture is used in cement production, its addition amount is 20-40% of the total mass of the cement.

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