Method for preparing sintered batten by using coal gangue

Abstract

The invention relates to a method for preparing a sintered batten by using coal gangue, which comprises the following steps: grinding raw materials of coal gangue, shale, feldspar and waste glass powder, sieving, taking 10-60-mesh coal gangue, less than 60-mesh coal gangue, shale, feldspar and waste glass powder, carrying out dry mixing, adding water, carrying out wet mixing, and aging the mixed pug; after the aged pug is pugged, a pug blank plate is extruded through a vacuum extruder; and drying the plate, and performing segmented high-temperature sintering to obtain the sintered hollow batten. According to the method, the production cost is low, waste coal gangue and waste glass powder are turned into wealth, the building board which is free of explosion points and made of a black core material is prepared, the technical problem that a product cannot be made large due to cracking in the drying process of the sintered batten is solved, and the hollow sintered batten with the size of 2800mm is successfully prepared. The batten can be prefabricated in a factory, standardized production of building components is achieved, and the building industry is promoted to be developed from traditional construction to industrialization.

Description

Technical Field

[0001] The present invention relates to a method for preparing sintered strip boards by using coal gangue, and belongs to the technical field of building material preparation. Background Art

[0002] Coal gangue is an industrial solid waste generated during coal mining and washing. It is a dark gray rock associated with coal seams during the coal formation process. It has a low carbon content and is harder than coal. Its types include driving gangue during roadway driving, natural gangue mined from the roof, floor, and interlayers during mining, and coal washing gangue separated during coal washing. Due to the huge production volume, it cannot be scaled up and disposed of in a timely manner, and can only be stockpiled locally, occupying land and bringing environmental pollution risks to the local area.

[0003] The main mineral component of coal gangue is clay mineral and it contains a certain amount of heat. To solve the environmental pollution problems it brings, coal gangue is usually used as an internal combustion raw material and added to sintered bricks. According to the different calorific values of coal gangue, semi-internal combustion bricks, full-internal combustion bricks, or super-internal combustion bricks can be made. However, no matter what kind of process, there is a problem of black core when using coal gangue to prepare sintered bricks, which directly affects the output and quality of sintered bricks.

[0004] To meet the requirements of green and low-carbon buildings and prefabricated buildings, sintered wall materials are developing from traditional brick and block products to strip board products. Sintered strip board is a new type of wall material that is obtained by high-temperature treatment to sinter the green body, densify the structure, and the reaction products are mainly silicate crystal phases. Its material is between ordinary sintered bricks and ceramics. Its size is usually above 2400mm. However, when using raw materials such as coal gangue for sintered bricks, due to the influence of material composition and process, the sintered strip board is prone to drying cracks during the drying process, resulting in the problem that the product cannot be made larger. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In order to solve the problems of explosion points, black core problems in the preparation of sintered materials using coal gangue in the prior art, and the problem that the sintered strip board cannot be made larger due to cracking during the drying process, the present invention provides a method for preparing sintered strip boards by using coal gangue.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the main technical solutions adopted by the present invention include:

[0009] A method for preparing sintered strip boards by using coal gangue, which comprises the following steps:

[0010] S1. Prepare raw coal gangue, shale, feldspar, and waste glass powder; grind the raw materials and then sieve them. Take coal gangue with a mesh size of 10 - 60 meshes and coal gangue, shale, feldspar, and waste glass powder with a mesh size less than 60 meshes for dry mixing.

[0011] S2. Add water to the dry - mixed materials for wet mixing, and let the mixed mud undergo retting.

[0012] S3. After retting, the mud is kneaded by a pug mill and then extruded into mud blank boards through a vacuum extruder.

[0013] S4. Dry the mud blank boards to reduce the moisture content of the mud blank boards.

[0014] S5. Segmentally sinter the dried boards at high temperature, continuously supply air during the sintering process, and cool down after sintering to obtain sintered hollow strip boards.

[0015] For the method described above, preferably, in step S1, the weight ratio of the coal gangue with a mesh size of 10 - 60 meshes to the coal gangue, shale, feldspar, and waste glass powder with a mesh size less than 60 meshes is 8 - 6:6 - 8:4:1:1.

[0016] For the method described above, preferably, in step S1, the weight ratio of the coal gangue with a mesh size of 10 - 60 meshes to the coal gangue, shale, feldspar, and waste glass powder with a mesh size less than 60 meshes is 8:6:4:1:1.

[0017] For the method described above, preferably, in step S1, the dry - mixing time is 20 - 30 min.

[0018] For the method described above, preferably, in step S2, the water consumption is 15 - 17% of the weight of the dry - mixed materials.

[0019] For the method described above, preferably, in step S2, the wet - mixing time is 10 - 20 min.

[0020] For the method described above, preferably, the retting time is 10 - 14 h.

[0021] For the method described above, preferably, in step S3, the shape of the mud blank board is a long strip board, its width is 200 mm, it is designed with double - row holes that are hollow up and down in the middle, the hole rate is 60%, there are columns connecting the upper and lower plate surfaces inside the board, the width of the columns is 15 mm, and the four corners inside the holes are designed with rounded corners with a radius of 10 mm.

[0022] For the method described above, preferably, in step S4, the drying conditions are: heating from room temperature to 180℃ at a heating rate of 1 - 5℃ / min, the drying cycle is 7 - 10 h, so that the moisture content of the dried blank board is ≤3%.

[0023] In a preferred embodiment, in step S5, the segmented high-temperature sintering is carried out by first holding at 500 °C for 60 min, treating at 850 °C for 60 min, and further roasting at 980 °C for 60 min.

[0024] (III) Beneficial effects

[0025] The beneficial effects of the present invention are as follows:

[0026] A method for preparing sintered strip plates using coal gangue provided by the present invention solves the problems of black core caused by lack of oxygen during sintering and drying cracks caused by excessive drying shrinkage of coal gangue while meeting the performance requirements through reasonable particle size distribution design, changing the type of common aggregates, and reasonable structure design.

[0027] The sintered strip plates prepared by the method provided by the present invention have low production costs, turn coal gangue and waste glass powder into treasures, prepare building plates without explosion points and black core materials, and solve the technical problem that it is difficult to make the size of sintered strip plates larger. The length can be increased to 2,800 mm. The strip plates meet the standard requirements of "Hollow Partition Strip Plates for Buildings"; they have low production costs, easy access to raw materials, deal with waste coal gangue and waste glass powder, and reduce the risk of environmental pollution; they can be prefabricated in factories to achieve standardized production of building components, and have high economic value in promoting the development of the construction industry from traditional construction to industrialization. Description of the drawings

[0028] Figure 1 It is a photo of the dried product in Example 1 of the present invention;

[0029] Figure 2 It is a photo of the dried product in Example 2 of the present invention;

[0030] Figure 3 It is a photo of the sintered products in Example 1 and Example 2 of the present invention;

[0031] Figure 4 It is a photo of the dried product in Comparative Example 2 of the present invention;

[0032] Figure 5 It is a photo of the dried product in Comparative Example 3 of the present invention;

[0033] Figure 6 It is a photo of the dried product in Comparative Example 4 of the present invention;

[0034] Figure 7 It is a photo of the dried product in Comparative Example 5 of the present invention;

[0035] Figure 8 It is a partial photo of the sintered product in Comparative Example 6 of the present invention. Detailed implementation manners

[0036] Through a large number of experimental studies, the inventor found that there are mainly three solutions to avoid the appearance of black cores after sintering: First, change the particle size distribution and increase the content of coarse particles to provide sufficient channels for oxygen during the sintering process to ensure complete internal combustion. Second, change the internal structure of the plate through die design and adopt a double-row hole design with a high porosity. Third, provide sufficient oxygen to enter during the sintering process through circulating air.

[0037] A good extrusion effect cannot be achieved with a single raw material. Usually, it is necessary to add plasticizers and aggregates externally to meet the extrusion requirements. For example, in the prior art, bluestone or brick waste is often used as an aggregate. However, through experiments, it is found that the content of limestone (CaCO3) in bluestone is relatively high. During the sintering process, limestone CaCO3 decomposes into calcium oxide (CaO), and the presence of calcium oxide causes the strip board to burst during the sintering process, generating explosion points on the surface. It is also found that the coarse particles in brick waste cannot react with coal gangue during the sintering process, and due to shrinkage during the sintering process, stress concentration occurs, causing the brick body to burst. The present invention uses coarse-grained coal gangue as an aggregate and solves the problems of drying cracking and sintering explosion by adjusting the particle size distribution of coal gangue. Research shows that the plasticity of coal gangue with a particle size of 10-60 mesh is poor and the drying sensitivity is low, while the plasticity of coal gangue with a particle size less than 60 mesh is good and the drying sensitivity is high. By adjusting the content of the two, the drying sensitivity and drying shrinkage rate of the mud are improved, thereby solving the problem of drying cracking. It should be noted that coal gangue with a particle size of 10-60 mesh refers to coal gangue particles with a particle size of 0.3-2 mm, and less than 60 mesh refers to particles with a particle size less than 0.3 mm.

[0038] The present invention provides a method for preparing sintered strip boards using coal gangue, which includes the following steps:

[0039] 1. Batching: In the present invention, coal gangue, shale, feldspar, and waste glass powder are selected as raw materials. The coal gangue is crushed and ground through a 10-mesh sieve and a 60-mesh sieve, and the shale, feldspar, and waste glass are crushed and ground through a 60-mesh sieve. By adjusting the proportion of the raw materials, the particle size distribution is controlled. When batching by weight ratio of 10-60 mesh coal gangue: 60 mesh coal gangue: 60 mesh shale: 60 mesh feldspar: 60 mesh glass powder, the particle size distribution is such that the powder with a particle size of 10 mesh to 40 mesh accounts for 20%-30%, the raw materials with a particle size of 40-100 mesh account for 20%-40%, and the powder with a particle size greater than 100 mesh accounts for 40%-60%.

[0040] Batching description:

[0041] (1) Raw material selection: The calorific value of the present invention is 1000cal / g. According to theoretical calculation, the blending amount to achieve complete internal combustion is 70%. Too much blending of coal gangue can easily cause black core. This scheme selects 70% blending amount as the research object. 10-60 mesh coal gangue has poor plasticity and low drying sensitivity. Too much will cause extrusion cracking, and too little will cause drying cracking. Coal gangue less than 60 mesh has higher plasticity and greater drying sensitivity; too little of it will cause extrusion cracking, and too much of it will cause drying cracking. In addition, shale is selected as a plasticizer to improve the plasticity of the raw material, and feldspar and glass powder are selected as sintering aids to promote sintering and reduce the sintering temperature of the product. According to a large number of experimental verifications, based on weight, the preferred ratio of 10-60 mesh gangue: 60 mesh gangue: 60 mesh shale: 60 mesh feldspar: 60 mesh glass powder = 8-6:6-8:4:1:1 is better; when 10-60 mesh gangue: 60 mesh gangue: 60 mesh shale: 60 mesh feldspar: 60 mesh glass powder = 8:6:4:1:1, the effect is best.

[0042] (2) Batching process: After weighing each raw material according to the proportion, add it into the mixer, dry mix it for 20 minutes, and then add 15-17% of the weight of the raw material for wet mixing for 15 minutes to form a mud material. The higher the water content added during batching, the greater the risk of cracking during the drying process. Too low water content will increase the difficulty of molding. According to the power of the extruder and the actual production situation, the optimal water content of the mud material formed by the present invention is preferably 13-14.6%.

[0043] 2. Aging: The mixed clay is transported to the aging warehouse for aging. Aging is used to improve the moisture distribution. Through capillary action, the moisture in the clay is more evenly distributed, thereby improving the moisture utilization rate and molding quality of the clay. It can also enhance plasticity. Clay particles are fully hydrated and ion exchanged during the aging process. Some silicate minerals are hydrolyzed and converted into clay substances due to long-term contact with water, thereby improving plasticity. The preferred aging temperature is 20℃~25℃, and the aging time is 10~14h.

[0044] 3. Extrusion: The aged clay is kneaded in a clay kneading machine and then extruded through a vacuum extruder. In order to increase the strength of the green body, eliminate pores and reduce defects, the vacuum degree is controlled at 0.09-0.1MPa.

[0045] In the present invention, the extruded sheet product is Figure 1As shown, the width of the board is 200 mm, which can effectively match the installation requirements. There are double rows of holes up and down inside, and the porosity is 60%. With the ventilation during the sintering process, complete internal combustion can be achieved, solving the problem of black cores after the brick blanks are sintered. There are columns connecting the upper and lower board surfaces inside the board. The width of the columns is 15 mm. The design of the columns running through up and down makes the middle crossbeam not subject to the pressure from the upper part, reducing the risk of cracking. The four corners inside the holes are designed as rounded corners with a radius of 10 mm, which can prevent cracking caused by stress concentration.

[0046] 4. Drying: The extruded boards are transferred to the drying room for drying. The temperature is raised from room temperature to 180 °C at a heating rate of 1 - 5 °C / min, and the drying time is 7 - 10 h. The moisture content of the dried blank boards is controlled at ≤3%. If the moisture content is too high, such as higher than 3%, the boards are prone to cracking during the subsequent high-temperature sintering process.

[0047] 5. Sintering: After the dried boards are transferred to the sintering kiln car, they enter the tunnel kiln for segmented high-temperature sintering. First, it is preferably kept at 500 °C for 60 min. At this temperature, the quartz crystal form transformation is more sufficient and stable, reducing defects such as internal stress and cracks caused by incomplete quartz crystal form transformation due to rapid heating; then it is treated at 850 °C for 60 min. At this temperature, physical and chemical reactions can be promoted, and the microstructure can be optimized to ensure the stable quality of the product. Further preferably, it is calcined at 980 °C for 60 min; if the temperature is too high, it will cause the color on the surface of the sample to turn black or dark, and shrink and deform; if the temperature is too low, it will cause phenomena such as powder falling off the surface of the sample and poor performance. During the sintering process, the boards are continuously supplied with air by a circulating fan to provide sufficient oxygen for the slats during sintering, ensuring complete internal combustion of the slats, solving the problem of black cores caused by lack of oxygen inside, and obtaining sintered hollow slat samples.

[0048] Refer to the relevant requirements in "Hollow Partition Slats for Building" (GB / T 23451 2023) and "Test Methods for Building Wall Panels" (GB / T 30100 2013) to conduct relevant tests on the compressive strength and water absorption of the sintered slats made in Examples 1 - 2 and Comparative Examples 1 - 6.

[0049] To better explain the present invention for easy understanding, the present invention will be described in detail below with reference to the accompanying drawings through specific embodiments.

[0050] Example 1

[0051] Select coal gangue, shale, feldspar, and waste glass powder as raw materials. Crush and grind the coal gangue and pass it through a 10-mesh sieve and a 60-mesh sieve respectively. Crush and grind the shale, feldspar, and waste glass and pass them through a 60-mesh sieve. Weigh 40 parts, 30 parts, 20 parts, 5 parts, and 5 parts of the selected coal gangue with a particle size of 10 - 60 mesh, 60-mesh coal gangue, shale, waste glass, and feldspar by weight, add them to a mixer, dry mix for 20 min, then add 17 parts of water and wet mix for 15 min. Transfer the mixed mud to a retting warehouse for retting for 12 h. After retting, the mud is kneaded by a pug mill and then extruded through a vacuum extruder to prepare a strip board with dimensions of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180℃ at a heating rate of 1 - 5℃ / min, and the drying cycle is 10 h. The moisture content of the dried board is 2.85%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for segmented high-temperature sintering. First, keep it at 500℃ for 60 min, then raise the temperature to 850℃ and treat it for 60 min, and further raise the temperature to 980℃ and roast it for 60 min. During the sintering process, continuously supply air to the board through a circulation fan, and let it cool naturally after sintering to obtain the product. Among them, the dried product is as shown in Figure 1 shown, and the sintered product is as shown in Figure 3 shown.

[0052] Product effect: It can be extruded into shape. The drying shrinkage rate of the green body is 4%. After sintering, there is no burst on the surface of the sample. After sintering, there is no black core inside the sample. The water absorption rate is 11.98%, and the compressive strength is 10.32 MPa.

[0053] Example 2

[0054] Select coal gangue, shale, feldspar, and waste glass powder as raw materials. Crush and grind the coal gangue and pass it through a 10-mesh sieve and a 60-mesh sieve respectively. Crush and grind the shale, feldspar, and waste glass and pass them through a 60-mesh sieve. Weigh 30 parts of the selected coal gangue with a particle size of 10 - 60 mesh, and 40 parts, 20 parts, 5 parts, and 5 parts of 60-mesh coal gangue, shale, waste glass, and feldspar by proportion respectively, add them to a mixer, dry mix for 20 min, then add 15 parts of water and wet mix for 15 min. Transfer the mixed mud to a retting warehouse for retting for 12 h. After retting, the mud is kneaded by a pug mill and then extruded through a vacuum extruder to prepare a strip board with dimensions of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180℃ at a heating rate of 1 - 5℃ / min, and the drying cycle is 8.5 h. The moisture content of the dried board is 2.65%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500℃ for 60 min, treat it at 850℃ for 60 min, and further roast it at 980℃ for 60 min. During the sintering process, continuously supply air to the board through a circulation fan, and let it cool naturally after sintering to obtain the product. Among them, the dried product is as shown in Figure 2 shown, and the sintered product is asFigure 3 as shown

[0055] Product effect: It can be extruded and formed. The drying shrinkage rate of the green body is 3.89%. After sintering, there is no bursting on the surface of the sample. After the sample is sintered, there is no black core inside. The water absorption rate of the sample is 11.45%, and the compressive strength is 11.58 MPa.

[0056] Comparative Example 1

[0057] Select coal gangue, shale, feldspar and waste glass powder as raw materials. Crush and grind the coal gangue and pass through 10-mesh sieve and 60-mesh sieve respectively. Crush and grind the shale, feldspar and waste glass and pass through 60-mesh sieve. Weigh 50 parts, 20 parts, 20 parts, 5 parts and 5 parts of the selected 10-60 mesh coal gangue, 60 mesh coal gangue, shale, waste glass and feldspar respectively and add them to a mixer. After dry mixing for 20 min, add 12 parts of water and wet mix for 15 min. Transfer the mixed mud to a aging warehouse for aging for 12 h. After aging, the mud is kneaded by a pug mill and then extruded through a vacuum extruder to prepare a strip board of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. The temperature is raised from room temperature to 180℃ at a heating rate of 1-5℃ / min, and the drying cycle is 7 h. The moisture content of the dried board is 2.75%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500℃ for 60 min, treat it at 850℃ for 60 min, and further roast it at 980℃ for 60 min. During the sintering process, continuous air supply is provided for the board through a circulation fan. The product is obtained after natural cooling during sintering.

[0058] Product effect: Difficult to extrude. The mud becomes hard during the extrusion process and cannot be extruded, blocking the die head.

[0059] Comparative Example 2

[0060] Select coal gangue, shale, feldspar, and waste glass powder as raw materials. Crush and grind the coal gangue, and sieve it through a 10-mesh sieve and a 60-mesh sieve respectively. Crush and grind the shale, feldspar, and waste glass, and sieve them through a 60-mesh sieve. Weigh 20 parts of the selected coal gangue with a particle size of 10 - 60 mesh, and 50 parts, 20 parts, 5 parts, and 5 parts of 60-mesh coal gangue, shale, waste glass, and feldspar respectively, and add them to a mixer. After dry mixing for 20 minutes, add 17 parts of water and wet mix for 15 minutes. Transfer the mixed mud to a retting warehouse for retting for 12 hours. After retting, the mud is refined by a pug mill and then extruded by a vacuum extruder to prepare a strip board with dimensions of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180°C at a heating rate of 1 - 5°C / min, and the drying cycle is 10 hours. The moisture content of the dried board is 2.78%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500°C for 60 minutes, treat it at 850°C for 60 minutes, and further roast it at 980°C for 60 minutes. During the sintering process, continuously supply air to the board through a circulating fan, and let it cool naturally after sintering to obtain the product.

[0061] Product effect: It can be extruded into shape. The drying shrinkage rate of the green body is 4.5%. Cracks appear at the ports of the samples after drying, as Figure 4 shown.

[0062] Comparative Example 3

[0063] Select coal gangue, shale, feldspar, bluestone, and waste glass powder as raw materials. Crush and grind the coal gangue, shale, feldspar, and waste glass, and sieve them through a 60-mesh sieve. Sieve the bluestone through a 10-mesh sieve. Weigh 70 parts, 5 parts, 5 parts, 5 parts, and 15 parts of the selected coal gangue, shale, waste glass, feldspar, and bluestone respectively, and add them to a mixer. After dry mixing for 20 minutes, add 16 parts of water and wet mix for 15 minutes. Transfer the mixed mud to a retting warehouse for retting for 12 hours. After retting, the mud is refined by a pug mill and then extruded by a vacuum extruder to prepare a strip board with dimensions of 2600×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180°C at a heating rate of 1 - 5°C / min, and the drying cycle is 8.5 hours. The moisture content of the dried board is 2.88%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500°C for 60 minutes, treat it at 850°C for 60 minutes, and further roast it at 980°C for 60 minutes. During the sintering process, continuously supply air to the board through a circulating fan, and let it cool naturally after sintering to obtain the product.

[0064] Product effect: It can be extruded into shape. The drying shrinkage rate of the green body is 5.4%. Cracks and fissures appear on the samples after drying, as Figure 5 shown.

[0065] Comparative Example 4

[0066] Select coal gangue, shale, feldspar, brick waste and waste glass powder as raw materials. Crush and grind coal gangue, shale, feldspar and waste glass through a 60-mesh sieve, and pass brick waste through a 10-mesh sieve. Weigh 70 parts, 5 parts, 5 parts, 5 parts and 15 parts of the selected coal gangue, shale, waste glass, feldspar and brick waste respectively and add them to a mixer. After dry mixing for 20 minutes, add 16 parts of water and wet mix for 15 minutes. Transfer the mixed mud to a retting warehouse for retting for 12 hours. After retting, the mud is kneaded by a pug mill and then extruded by a vacuum extruder to prepare a strip board of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180°C at a heating rate of 1-5°C / min, and the drying cycle is 8.5 hours. The moisture content of the dried board is 2.85%; after the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500°C for 60 minutes, treat it at 850°C for 60 minutes, and further roast it at 980°C for 60 minutes. During the sintering process, continuously supply air to the board through a circulation fan, and the product is obtained after natural cooling during sintering.

[0067] Effect: It can be extruded into shape. The drying shrinkage rate of the green body is 5.5%. Cracks appear after the sample is dried, as Figure 6 shown.

[0068] Comparative Example 5

[0069] Select coal gangue, shale, feldspar, bluestone and waste glass powder as raw materials. Crush and grind coal gangue, shale, feldspar and waste glass through a 60-mesh sieve, and pass bluestone through a 10-mesh sieve. Weigh 60 parts, 5 parts, 5 parts, 5 parts and 25 parts of the selected coal gangue, shale, waste glass, feldspar and bluestone respectively and add them to a mixer. After dry mixing for 20 minutes, add 16 parts of water and wet mix for 15 minutes. Transfer the mixed mud to a retting warehouse for retting for 12 hours. After retting, the mud is kneaded by a pug mill and then extruded by a vacuum extruder to prepare a strip board of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. Heat it from room temperature to 180°C at a heating rate of 1-5°C / min, and the drying cycle is 9 hours. The moisture content of the dried board is 2.79%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500°C for 60 minutes, treat it at 850°C for 60 minutes, and further roast it at 980°C for 60 minutes. During the sintering process, continuously supply air to the board through a circulation fan, and the product is obtained after natural cooling during sintering.

[0070] Effect: It can be extruded into shape. The drying shrinkage rate of the green body is 4.1%. Severe cracking appears on the surface of the sintered sample, as Figure 7 shown. There is no black core inside. The water absorption rate of the sample is 13.56%, and the compressive strength is 7.89 MPa.

[0071] Comparative Example 6

[0072] Select coal gangue, shale, feldspar, brick slag and waste glass powder as raw materials. Crush and grind coal gangue, shale, feldspar and waste glass through a 60-mesh sieve, and pass brick slag through a 10-mesh sieve. Weigh the selected coal gangue, shale, waste glass, feldspar and brick slag according to the proportions of 60 parts, 5 parts, 5 parts, 5 parts and 25 parts, and add them to a mixer. After dry mixing for 20 minutes, add 16 parts of water and wet mix for 15 minutes. Transfer the mixed mud to a retting warehouse for retting for 12 hours. After retting, the mud is pugged by a pug mill and then extruded by a vacuum extruder to prepare a strip board of 2800×600×200 mm. The extruded board is transferred to a drying room for drying. The temperature is raised from room temperature to 180°C at a heating rate of 1-5°C / min, and the drying cycle is 9 hours. The moisture content of the dried board is 2.75%. After the dried board is transferred to a sintering kiln car, it enters a tunnel kiln for high-temperature sintering. First, keep it at 500°C for 60 minutes, treat it at 850°C for 60 minutes, and further roast it at 980°C for 60 minutes. During the sintering process, continuous air supply is provided to the board through a circulation fan. After sintering and natural cooling, the product is obtained.

[0073] Effect: It can be extruded into shape. The drying shrinkage rate of the green body is 4.12%. After sintering, cracks appear on the surface of the sample, as Figure 8 shown. There is no black core inside. The water absorption rate of the sample is 12.56%, and the compressive strength is 8.12 MPa.

[0074] Compared with the existing products, the products prepared by the present invention are larger in size (2800 mm). The sizes of the products visible on the market are generally 1600 mm. Through the improvement of the product formula and process control of the present invention, the technical problem that the size of conventional products cannot be made larger can be solved. The previous products were manually laid, which was time-consuming and had a high labor cost. However, the products of the present invention belong to assembled new building materials and can be mechanically assembled by robots, with a fast assembly speed and labor cost savings. The method of the present invention uses coal gangue as the main raw material, which can dispose of solid waste, can be used to earn solid waste treatment fees, and turn waste into treasure.

[0075] The method for preparing sintered strip boards using coal gangue provided by the present invention not only turns coal gangue into treasure and prepares building boards without black core materials, but also its application in preparing sintered strip boards meets the requirements of today's green and low-carbon buildings and assembled buildings, enabling the sintered strip boards to reach a length of 2800 mm, meeting the standard requirements of "Hollow Partition Strip Boards for Buildings", with low production costs and easy access to raw materials. It not only disposes of waste coal gangue and waste glass powder, reduces environmental pollution, but also the produced building materials have high economic value.

[0076] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in any other form. Any person skilled in the art can use the disclosed technical content above to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing sintered strip boards using coal gangue, characterized in that, It includes the following steps: S1. Prepare raw coal gangue, shale, feldspar, and waste glass powder; grind the raw materials and then sieve them. Take coal gangue with a particle size of 10 - 60 mesh and coal gangue, shale, feldspar, and waste glass powder with a particle size less than 60 mesh for dry mixing; S2. Add water to the dry - mixed materials for wet mixing, and let the mixed mud undergo retting; S3. After retting, the mud is kneaded by a pug mill and then extruded into mud blank boards through a vacuum extruder; S4. Dry the mud blank boards to reduce the moisture content of the mud blank boards; S5. Segmentally sinter the dried boards at high temperature, continuously supply air during the sintering process, and cool down after sintering to obtain sintered hollow slab; 2. The method according to claim 1, characterized in that, In step S1, the weight ratio of the 10 - 60 - mesh coal gangue to the coal gangue, shale, feldspar, and waste glass powder with a particle size less than 60 mesh is 8 - 6:6 - 8:4:1:

1.

3. The method according to claim 1, characterized in that, In step S1, the weight ratio of the 10 - 60 - mesh coal gangue to the coal gangue, shale, feldspar, and waste glass powder with a particle size less than 60 mesh is 8:6:4:1:

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4. The method according to claim 1, characterized in that In step S1, the dry - mixing time is 20 - 30 min.

5. The method according to claim 1, wherein In step S2, the water consumption is 15 - 17% of the weight of the dry - mixed materials.

6. The method according to claim 1, characterized in that In step S2, the wet - mixing time is 10 - 20 min.

7. The method according to claim 1, characterized in that, The retting temperature is controlled at 20°C - 25°C, and the retting time is 10 - 14 h.

8. The method according to claim 1, wherein In step S3, the shape of the mud blank board is a long strip board, its width is 200 mm, and it is designed with double - row holes that are hollowed out up and down in the middle. The porosity is 60%. There are columns connecting the upper and lower plates inside the board. The width of the columns is 15 mm, and the four corners inside the holes are designed with rounded corners with a radius of 10 mm.

9. The method according to claim 1, characterized in that In step S4, the drying conditions are as follows: the heating rate is 1 - 5°C / min, heating from room temperature to 180°C, and the drying time is 7 - 10 h, so that the moisture content of the dried blank board is ≤3%.

10. The method according to claim 1, characterized in that, In step S5, the segmental high - temperature sintering is as follows: first, keep the temperature at 500°C for 60 min, treat it at 850°C for 60 min, and further roast it at 980°C for 60 min.

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