Preparation method of coal gangue ceramsite
The treatment of coal gangue raw spheres through microwave drying and pyrolysis processes has solved the high-temperature adhesion problem caused by volatile components in traditional belt roasting, and achieved stable production of coal gangue ceramics and high-quality products.
Patent Information
- Application Number
- CN202510527261.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-07-18
AI Technical Summary
The volatile components of the traditional belt roasting method are rapidly precipitated during the pyrolysis stage, causing local overheating of the material layer, causing high temperature zones and adhesions, affecting the smooth operation of the production process, and unstable product quality.
The coal gangue spheres are pretreated by microwave drying and microwave pyrolysis processes, and the volatile components are quickly dehydrated through microwave drying and released at a specific temperature to avoid a sharp rise in the material layer temperature and ensure production continuity in combination with the roasting process.
It effectively avoids the bonding of material layers, ensures the continuity of production and product quality stability, improves the production efficiency and quality of coal gangue ceramics, and obtains high-strength and low-residual carbon ceramics.
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Abstract
Description
Technical Field
[0001] This application relates to the technical field of solid waste utilization, and specifically relates to a preparation method of coal gangue ceramsite. Background Art
[0003] In response to the production demand of coal gangue ceramsite, the industry has developed a variety of process routes to meet the requirements of different application scenarios. Traditional treatment methods mainly include rotary kiln technology and belt roasting method, etc. Among them, the rotary kiln technology realizes the heating and reaction process control of materials by continuously rotating the kiln body. However, this method has problems such as high energy consumption, low production efficiency, serious environmental pollution, and poor product quality stability, and its market application rate is relatively low; while the belt roasting method completes the decarbonization and sintering forming processes of coal gangue green balls with the help of a multi-layer cloth system and a specific temperature control curve, effectively improving the problems of product quality stability and production capacity scale. However, this method still has some technical bottlenecks. For example, in the key pyrolysis stage, due to the rapid evolution of volatile components, local overheating occurs, resulting in uncontrollable high-temperature zones or even melting and adhesion in the material layer, thus destroying the normal ventilation conditions and hindering the achievement of the subsequent complete decarbonization goal, directly affecting the smooth operation of the entire production process. Summary of the Invention
[0004] In order to overcome the problems such as the temperature of the material layer in the pyrolysis stage of the existing belt roasting method is likely to rise sharply, resulting in adhesion and caking of the material layer, this application provides a preparation method of coal gangue ceramsite.
[0005] The preparation method of coal gangue ceramsite provided by this application adopts the following technical solutions: A preparation method of coal gangue ceramsite, comprising the following steps: microwave drying, microwave pyrolysis and roasting; Microwave drying: Feed the coal gangue green balls into Microwave Device I, and perform gradient heating at a power density of 1.5 - 2.5 W / g to raise the temperature to 120 - 150 °C Microwave pyrolysis: Feed the coal gangue green balls after microwave drying into Microwave Device II, and perform gradient heating at a power density of 3 - 5 W / g. First, raise the temperature to 250 - 350 °C and keep it warm for 5 - 15 min; then raise the temperature to 350 - 500 °C and keep it warm for 10 - 25 min.
[0006] The present application provides a method for preparing coal gangue ceramsite. This method introduces the processes of microwave drying and microwave pyrolysis to pre-treat the green balls of coal gangue before roasting, significantly reducing the water content of the green balls of coal gangue. At the same time, volatile components (combustible gases such as CO, hydrogen, methane, etc.) are fully released and collected; effectively avoiding the problem that the temperature of the material layer is prone to rise sharply due to volatile components, resulting in the adhesion and caking of the material layer, thus ensuring the continuous progress of the subsequent roasting process. Specifically: First, the green balls of coal gangue are quickly and evenly dehydrated by microwave drying. While ensuring the stability of the physical and chemical properties of the green balls, the water content of the green balls is reduced to 1-2% within a short time, and the temperature is raised to 120-150 °C, avoiding explosion due to residual moisture in the subsequent process. Then, the green balls of coal gangue are subjected to microwave pyrolysis at a specific temperature. In the first stage of pyrolysis (250-350 °C), the bound water in the green balls is effectively removed, and in the second stage (350-500 °C), the volatile components in the green balls are effectively released and collected. Compared with methods such as high-temperature gas pyrolysis in related technologies, the pyrolysis process in this case only acts on the green balls themselves, and the ambient temperature is relatively low. Therefore, the temperature of the material layer will not rise sharply, thus avoiding the problem of adhesion and caking of the material layer. In summary, the method for preparing coal gangue ceramsite provided by the present application can reduce the content of volatile components in the green balls while ensuring that the material layer during pyrolysis does not cake due to high temperature, guaranteeing the smooth operation of the entire production process.
[0007] In some embodiments, the power density in the microwave drying step can be 1.5-2 W / g or 2-2.5 W / g.
[0008] In a specific embodiment, the power density in the microwave drying step can be 1.5 W / g, 2 W / g, or 2-2.5 W / g.
[0009] In some embodiments, the power density in the microwave pyrolysis step can be 3-4 W / g or 4-5 W / g.
[0010] In a specific embodiment, the power density in the microwave pyrolysis step can be 3 W / g, 4 W / g, or 5 W / g.
[0011] In some embodiments, the temperature after heating in the first stage of the microwave pyrolysis step can be 250-300 °C or 300-350 °C.
[0012] In a specific embodiment, the temperature after heating in the first stage of the microwave pyrolysis step can also be 250 °C, 300 °C, or 350 °C.
[0013] In some embodiments, the heating time in the first stage of the microwave pyrolysis step can be 5 - 10 min or 10 - 15 min.
[0014] In a specific embodiment, the heating time in the first stage of the microwave pyrolysis step can also be 5 min, 10 min or 15 min.
[0015] In some embodiments, the temperature after heating in the second stage of the microwave pyrolysis step can be 350 - 400 °C, 350 - 450 °C, 350 - 500 °C, 400 - 450 °C, 400 - 500 °C or 450 - 500 °C.
[0016] In a specific embodiment, the temperature after heating in the second stage of the microwave pyrolysis step can also be 350 °C, 400 °C, 450 °C or 500 °C.
[0017] In some embodiments, the heating time in the first stage of the microwave pyrolysis step can be 10 - 15 min or 15 - 25 min.
[0018] In a specific embodiment, the heating time in the first stage of the microwave pyrolysis step can also be 10 min, 15 min or 25 min.
[0019] Optionally, the water content of the green pellets of coal gangue after microwave drying is 1 - 2%.
[0020] Optionally, the volatile content of the green pellets of coal gangue after microwave pyrolysis is ≤5%.
[0021] Optionally, the frequency of the microwave device I is 2.45 GHz, and the frequency of the microwave device II is 915 MHz.
[0022] Optionally, the moisture content of the green pellets of coal gangue is 10 - 14%, and the particle size is 8 - 15 mm.
[0023] Optionally, the coal gangue ceramsite is high-strength coal gangue ceramsite or water-retaining coal gangue ceramsite.
[0024] Optionally, when the coal gangue ceramsite is high-strength coal gangue ceramsite, the specific steps of roasting are as follows: feeding the green pellets of coal gangue after microwave pyrolysis into a roasting machine, decarbonizing at 500 - 700 °C for 40 - 60 min, then sintering at 900 - 1200 °C for 10 - 15 min, and finally cooling with fresh air to below 100 °C to obtain high-strength coal gangue ceramsite.
[0025] Optionally, when the coal gangue ceramsite is water-retaining coal gangue ceramsite, the specific steps of roasting are as follows: feeding the green balls of coal gangue after microwave pyrolysis into a roasting machine, decarbonizing at 500 - 700 °C for 40 - 60 min, and finally cooling with fresh air to below 100 °C to obtain water-retaining coal gangue ceramsite.
[0026] Optionally, the thickness of the material layer of the green balls of coal gangue in the roasting machine is 300 - 900 mm, the porosity of the material layer is 25 - 40%, and the air velocity in the material layer is 0.5 - 1.5 m / s.
[0027] In summary, the present application has the following beneficial effects: 1. The present application provides a preparation method of coal gangue ceramsite. This preparation method first quickly and evenly removes the moisture in the green balls of coal gangue by microwave drying, reducing its moisture content to less than 2%, effectively avoiding the bursting problem caused by moisture residue in the subsequent process; then releases the volatile components in the green balls of coal gangue by microwave pyrolysis, effectively preventing the appearance of liquid phase on the surface of the green balls and the agglomeration of the material layer during the subsequent roasting process, ensuring the smooth progress of the air permeability of the material layer and the decarbonization process.
[0028] 2. By combining microwave pretreatment with the roasting process, the present application realizes the continuous and stable production of coal gangue ceramsite, solves the high-temperature adhesion problem existing in the pyrolysis stage of the traditional belt roasting machine, and improves the reliability of production and the product quality.
[0029] 3. The preparation method of coal gangue ceramsite provided by the present application can significantly improve the production efficiency and product quality of coal gangue ceramsite, and obtain high-strength coal gangue ceramsite with a cylinder compressive strength of ≥7 MPa, a calorific value of <100 kcal / kg, and a residual carbon of <2%. Description of the Drawings
[0030] Figure 1 is a flow chart of the preparation method of coal gangue ceramsite provided by the present application. Detailed Embodiments
[0031] The present application provides a preparation method of high-strength coal gangue ceramsite, including the following steps: (1) Microwave drying: Taking coal gangue raw materials to granulate into green balls of coal gangue with a diameter of 8 - 15 mm and a moisture content of 10 - 14%; feeding the green balls of coal gangue into a 2.45 GHz microwave device for microwave drying, performing gradient heating at a power density of 1.5 - 2.5 W / g to raise the temperature to 120 - 150 °C, so that the moisture content of the green balls of coal gangue is reduced to less than 2%; (2) Microwave pyrolysis: The green pellets of coal gangue after microwave drying are fed into a 915 MHz microwave device for microwave pyrolysis, and gradient heating is carried out at a power density of 3 - 5 W / g. First, it is heated to 250 - 350 °C and kept warm for 5 - 15 min; then it is further heated to 350 - 500 °C and kept warm for 10 - 25 min, so that the volatile content of the green pellets of coal gangue is reduced to less than 5%.
[0032] (3) Roasting: The green pellets of coal gangue after microwave pyrolysis are fed into a roasting machine, so that the thickness of the material layer is 300 - 900 mm, the porosity of the material layer is 25 - 40%, and the air velocity in the material layer is 0.5 - 1.5 m / s; then decarbonization is carried out at 500 - 700 °C for 40 - 60 min; then sintering is carried out at 900 - 1200 °C for 10 - 15 min; finally, it is cooled to below 100 °C with fresh air to obtain high-strength coal gangue ceramsite.
[0033] The present application provides a preparation method of water-retaining coal gangue ceramsite, and the difference from the preparation method of the above high-strength coal gangue ceramsite is step (3), which is specifically as follows: (3) Roasting: The green pellets of coal gangue after microwave pyrolysis are fed into a roasting machine, so that the thickness of the material layer is 300 - 900 mm, the porosity of the material layer is 25 - 40%, and the air velocity in the material layer is 0.5 - 1.5 m / s; then decarbonization is carried out at 500 - 700 °C for 40 - 60 min; finally, it is cooled to below 100 °C with fresh air to obtain water-retaining coal gangue ceramsite.
[0034] The raw materials, reagents, solvents, etc. used in the present application can all be obtained through commercial purchase.
[0035] The following further describes the present application in detail in conjunction with examples, performance detection tests and attached drawings. Example 1
[0036] Example 1 provides a preparation method of high-strength coal gangue ceramsite.
[0037] The preparation method of the above high-strength coal gangue ceramsite includes the following steps: (1) Granulation and microwave drying: Take coal gangue raw materials (SiO2 52%, Al2O3 28%, calorific value 550 kcal / kg, fixed carbon content 6%, volatile matter 11%) and granulate them into green pellets of coal gangue with a size of 12 ± 1 mm and a moisture content of 13%; feed the green pellets of coal gangue into a 2.45 GHz microwave device for microwave drying, and carry out gradient heating at a power density of 2 W / g to raise the temperature to 140 °C; Among them, the water vapor generated by microwave drying is discharged into the atmosphere after treatment; (2) Microwave pyrolysis: The green pellets of coal gangue after microwave drying are fed into a 915 MHz microwave device for microwave pyrolysis, and gradient heating is carried out at a power density of 4 W / g. First, it is heated to 300 °C and held for 10 min; then it is further heated to 450 °C and held for 15 min; Among them, the volatile components (combustible gases such as CO, hydrogen, and methane) generated during the pyrolysis process are ignited and heated through a pipeline and a burner, and then transported to the decarbonization section of the sintering machine for use; (3) Roasting: The green pellets of coal gangue after microwave pyrolysis are fed into a roasting machine, with the thickness of the material layer being 600 mm, the porosity of the material layer being 30%, and the air velocity in the material layer being 1 m / s; then decarbonization is carried out at 550 °C for 45 min; then sintering is carried out at 1100 °C for 15 min; finally, it is cooled to 80 °C with fresh air to obtain high-strength coal gangue ceramsite; Among them, the high-temperature flue gas generated after decarbonization and sintering is sent to the preheating recovery system through a pipeline. Example 2 - 10
[0038] Examples 2 - 10 respectively provide a preparation method of high-strength coal gangue ceramsite.
[0039] The differences between the above examples and Example 1 are as follows: the parameters in the microwave drying and microwave pyrolysis steps are shown in Table 1 below. Comparative Examples 1 - 2
[0040] Comparative Examples 1 - 2 respectively provide a preparation method of high-strength coal gangue ceramsite.
[0041] The differences between the above comparative examples and Example 1 are as follows: the parameters in the microwave drying and microwave pyrolysis steps are shown in Table 1 below.
[0042] Table 1 Parameters in the microwave drying and microwave pyrolysis steps of Examples 1 - 10 and Comparative Examples 1 - 2 Example 11
[0043] Example 11 provides a preparation method of water-retaining coal gangue ceramsite.
[0044] The above preparation method of water-retaining coal gangue ceramsite includes the following steps: (1) Granulation and microwave drying: Take coal gangue raw materials (SiO2 49%, Al2O3 30%, calorific value 600 kcal / kg, fixed carbon content 6.5%, volatile matter 10.7%) and granulate them into green pellets of coal gangue with a size of 12 ± 1 mm and a water content of 12.5%; feed the green pellets of coal gangue into a 2.45 GHz microwave device for microwave drying, and carry out gradient heating at a power density of 2 W / g to raise the temperature to 130 °C; (2) Microwave pyrolysis: The green pellets of coal gangue after microwave drying are fed into a 915 MHz microwave device for microwave pyrolysis. Gradient heating is carried out at a power density of 4 W / g. First, it is heated to 300 °C and kept warm for 10 min; then it is further heated to 450 °C and kept warm for 15 min. (3) Roasting: The green pellets of coal gangue after microwave pyrolysis are fed into a roasting machine, with the layer thickness of the material being 600 mm, the porosity of the material layer being 30%, and the air velocity inside the material layer being 1 m / s; then decarbonization is carried out at 550 °C for 45 min; finally, it is cooled to 80 °C with fresh air to obtain water-retaining ceramsite of coal gangue, and its water absorption rate in 24 h is 21%. Comparative Example 3
[0045] Comparative Example 3 provides a preparation method of high-strength ceramsite of coal gangue, including the following steps: (1) Microwave treatment: Take coal gangue raw materials (SiO2 52%, Al2O3 28%, calorific value 550 kcal / kg, fixed carbon content 6%, volatile matter 11%) and granulate them into green pellets of coal gangue with a size of 12 ± 1 mm and a moisture content of 13%; the green pellets of coal gangue are fed into a 2.45 GHz microwave device, and gradient heating is carried out at a power density of 2 W / g to raise the temperature to 450 °C. (3) Roasting: The green pellets of coal gangue after microwave treatment are fed into a roasting machine, with the layer thickness of the material being 600 mm, the porosity of the material layer being 30%, and the air velocity inside the material layer being 1 m / s; then decarbonization is carried out at 550 °C for 45 min; then sintering is carried out at 1100 °C for 15 min; finally, it is cooled to 80 °C with fresh air to obtain high-strength ceramsite of coal gangue. Performance detection test
[0046] The coal gangue ceramsite obtained from Examples 1 - 11 and Comparative Examples 1 - 3 are subjected to various index detections, and the results are shown in Table 2 below.
[0047] (1) Bulk density: The bulk density of coal gangue ceramsite is detected by the vibration compaction method.
[0048] (2) Cylinder compressive strength: The cylinder compressive strength of coal gangue ceramsite is detected by the standard cylinder compression test.
[0049] (3) Calorific value: The calorific value of coal gangue ceramsite is measured by an oxygen bomb calorimeter.
[0050] (4) Residual carbon: The dried sample of coal gangue ceramsite is placed in a crucible of a muffle furnace, calcined at 900 °C for 7 min, and the remaining residue is ashed at 550 °C for 2 h to calculate the fixed carbon content.
[0051] Table 2 Detection results of various indexes of coal gangue ceramsite obtained from Examples 1 - 11 and Comparative Examples 1 - 3
[0052] According to the test results in Table 2, in Examples 1-10 of the present application, by adopting steps such as microwave drying, microwave pyrolysis and roasting, and adjusting the processes of microwave drying and microwave pyrolysis within a specific range, coal gangue high-strength ceramsite with a bulk density of 680-734 kg / m 3 , a cylinder compressive strength of 8.2-9.0 MPa, a calorific value <100 kcal / kg, and a residual carbon <2% was obtained; in Comparative Example 1, the power density in the microwave drying step was controlled at 3 W / g, and the temperature after heating was adjusted to 100 °C. After preparing many times according to the above method, the coal gangue green balls occasionally burst during the pyrolysis process; in Comparative Example 2, the power density in the microwave pyrolysis step was controlled at 8 W / g, the temperature after the first-stage heating was adjusted to 200 °C, and the temperature after the second-stage heating was adjusted to 300 °C, resulting in incomplete removal of volatile components in the green balls. The volatile components continued to precipitate during the decarbonization process, causing the material layer in the decarbonization section to become compacted and the obtained ceramsite to have a black core; in Comparative Example 3, only one-step microwave treatment was used, which would cause the volatile components to burn in the material layer, resulting in compaction of the material layer and the obtained ceramsite having a black core. Therefore, it shows that by sequentially performing microwave drying and microwave pyrolysis on coal gangue green balls under specific conditions, the present application can significantly reduce the bulk density of coal gangue green balls, make them have good air permeability, and further ensure that the heat during the roasting process can be quickly and thoroughly dissipated, effectively avoiding the accumulation of high-temperature gases, ensuring complete subsequent decarbonization, and enabling continuous and stable production.
[0053] The preparation method of coal gangue ceramsite provided by the present application can solve the adverse effects of high temperature generated by the combustion of volatile components in the traditional method on the green balls, eliminate the occurrence of material layer compaction phenomenon from the root cause, and thus can continuously and stably obtain high-quality coal gangue high-strength ceramsite. The cylinder compressive strength of the obtained coal gangue high-strength ceramsite is ≥7 MPa, the calorific value <100 kcal / kg, and the residual carbon <2%.
[0054] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.
Claims
1. A preparation method of coal gangue ceramsite, characterized in that, It includes the following steps: Microwave drying, microwave pyrolysis and roasting; Microwave drying: Feed the green pellets of coal gangue into Microwave Device I and conduct gradient heating at a power density of 1.5 - 2.5 W / g to raise the temperature to 120 - 150 °C; Microwave pyrolysis: Feed the green pellets of coal gangue after microwave drying into Microwave Device II and conduct gradient heating at a power density of 3 - 5 W / g. First, raise the temperature to 250 - 350 °C and keep it warm for 5 - 15 min; then raise the temperature to 350 - 500 °C and keep it warm for 10 - 25 min.
2. The preparation method of the coal gangue ceramsite according to claim 1, characterized in that, The water content of the green pellets of coal gangue after microwave drying is 1 - 2%.
3. The preparation method of the coal gangue ceramsite according to claim 1, characterized in that The volatile content of the green pellets of coal gangue after microwave pyrolysis is ≤5%.
4. The preparation method of the coal gangue ceramsite according to claim 1, characterized in that, The frequency of Microwave Device I is 2.45 GHz, and the frequency of Microwave Device II is 915 MHz.
5. The preparation method of the coal gangue ceramsite according to claim 1, wherein The water content of the green pellets of coal gangue is 10 - 14%, and the particle size is 8 - 15 mm.
6. The preparation method of the coal gangue ceramsite according to claim 1, characterized in that The coal gangue ceramsite is either high-strength coal gangue ceramsite or water-retaining coal gangue ceramsite.
7. The preparation method of coal gangue ceramsite according to any one of claims 1-6, characterized in that, When the coal gangue ceramsite is high-strength coal gangue ceramsite, the specific steps of roasting are as follows: Feed the green pellets of coal gangue after microwave pyrolysis into a roasting machine, decarbonize at 500 - 700 °C for 40 - 60 min, then sinter at 900 - 1200 °C for 10 - 15 min, and finally cool with fresh air to below 100 °C to obtain high-strength coal gangue ceramsite.
8. The preparation method of the coal gangue ceramsite according to any one of claims 1-6, characterized in that, When the coal gangue ceramsite is water-retaining coal gangue ceramsite, the specific steps of roasting are as follows: Feed the green pellets of coal gangue after microwave pyrolysis into a roasting machine, decarbonize at 500 - 700 °C for 40 - 60 min, and finally cool with fresh air to below 100 °C to obtain water-retaining coal gangue ceramsite.
9. The preparation method of coal gangue ceramsite according to claim 7 or 8, characterized in that, The thickness of the material layer of the green pellets of coal gangue in the roasting machine is 300 - 900 mm, the porosity of the material layer is 25 - 40%, and the air velocity in the material layer is 0.5 - 1.5 m / s.