A method for preparing high-temperature-resistant ceramsite
By using refractory cement and low-temperature firing processes, the problems of high energy consumption and unevenness in the preparation of high-temperature resistant ceramsite have been solved, and ceramsite with high strength and high heat resistance has been prepared, which is suitable for casting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIUZHOU LIUJING ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2024-06-04
- Publication Date
- 2026-06-19
AI Technical Summary
Existing technologies for preparing high-temperature resistant ceramsite have high energy consumption, require specialized equipment, and are difficult to control in terms of temperature and time, resulting in high production costs, uneven ceramsite production, and cracking problems.
Using refractory cement and low-temperature firing process, refractory cement and water are added to the ball-milled mixture A, granulated and then fired at low temperature to form a high-strength ceramic structure, avoiding high-temperature firing.
It reduces energy consumption, improves the refractoriness and strength of ceramsite, achieves uniformity and stability of ceramsite, is suitable for casting, and reduces production costs.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of ceramsite production technology, and in particular to a method for preparing high-temperature resistant ceramsite. Background Technology
[0002] Foundry dust is powdery waste from foundries, primarily originating from the sand treatment department during casting production and collected by dust removal equipment. Machining, grinding, and sand removal processes in casting operations also generate significant amounts of dust. Long-term exposure to foundry dust can damage workers' respiratory systems, leading to occupational diseases such as pneumoconiosis, and can also pollute the environment, affecting air quality.
[0003] To address the environmental challenges of casting dust disposal, an innovative technology has been developed in recent years to recycle and reuse this waste dust, processing it into high-temperature resistant ceramic granules using a specific process. This process begins by purifying the collected casting dust to remove harmful impurities. The purified dust is then mixed uniformly with an appropriate proportion of binder, granulated into particles of a specific shape and size using a granulator, and finally fired at 1300℃ to induce a ceramicization reaction within the granules. During this process, the binder between the dust particles is burned off or transformed, while the dust particles undergo high-temperature recombination, forming a dense and high-strength ceramic structure that exhibits excellent heat resistance and stability.
[0004] However, high-temperature firing not only consumes a lot of energy but also places special requirements on equipment, increasing production costs. Furthermore, precisely controlling the firing temperature and time to ensure uniform ceramsite emulsification and prevent cracking or deformation remains a major technical challenge. Therefore, although using casting dust to prepare high-temperature resistant ceramsite provides a new approach to the resource utilization of waste, continuous optimization of process parameters and development of more efficient and energy-saving firing technologies are still needed to achieve the widespread application and sustainable development of this technology. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides a method for preparing high-temperature resistant ceramsite. By using refractory cement and a low-temperature firing process, high-temperature resistant ceramsite with high compressive strength and refractoriness is prepared. This eliminates the need for a high-temperature firing process to form a ceramic structure, simplifying the preparation process and effectively reducing energy consumption.
[0006] The present invention adopts the following technical solution:
[0007] This invention provides a method for preparing high-temperature resistant ceramsite, comprising the following steps:
[0008] (1) Add bauxite to the calcined ash and ball mill it to obtain mixture A; specifically, the calcined ash is the calcined ash that is discharged together with the recycled ash after the dust-like solid waste generated in the casting process is incinerated.
[0009] (2) Add refractory cement and water to mixture A, stir evenly to obtain ceramsite cores, and then granulate to obtain primary ceramsite.
[0010] (3) Curing, drying and screening of primary ceramsite;
[0011] (4) The initial ceramsite after screening is subjected to two-stage low-temperature firing. The first stage firing is carried out at 120-130℃ for 1.5-2 hours, and the second stage firing is carried out at 680-750℃ for 2-3 hours to burn off the organic matter and combustible substances in the ceramsite.
[0012] Furthermore, the raw materials for the high-temperature resistant ceramsite are composed of the following raw materials in weight percentage: 35-50% calcined ash, 20-25% bauxite, 18-25% refractory cement, and 12-15% water; specifically, the refractory cement is cement with a refractoriness of not less than 1500℃.
[0013] Furthermore, in step (1), the particle size of mixture A is not higher than 1000 mesh.
[0014] Furthermore, in step (2), the stirring method is to use a high-speed mixer with a cylinder speed of 200-300 r / min, a rotor speed of 3000-4000 r / min, and a stirring time of 2-4 min.
[0015] Furthermore, in step (2), the granulation method is to use a round pot granulator, and the granulation time is 45-60 minutes, so as to make the ceramsite core compact and obtain a certain initial strength, thus obtaining the initial ceramsite.
[0016] Furthermore, in step (3), the maintenance method is natural maintenance, and the maintenance time is 12-24 hours.
[0017] Furthermore, the drying temperature in step (3) is 65-70℃ to avoid cracks appearing in the initial ceramsite.
[0018] Furthermore, the initial ceramsite particle size screened in step (3) is 40 / 200 mesh; excessively fine and excessively coarse ceramsite particles are removed so that the ceramsite particles can meet the requirements for casting.
[0019] Compared with the prior art, the beneficial effects of the present invention are:
[0020] 1. This invention can greatly improve the refractoriness of ceramsite by adding bauxite and refractory cement, with a refractoriness ≥1700℃; by adding refractory cement, the ceramsite has sufficient strength, and can meet the casting requirements without high-temperature firing to form a ceramic structure, effectively reducing energy consumption, maximizing energy utilization, and avoiding energy waste caused by high-temperature firing.
[0021] 2. The ceramic reaction does not occur during the preparation of the ceramsite in this invention. Instead, the ceramsite undergoes an endothermic ceramicization reaction by utilizing the heat from the casting process, making it more suitable for heat-resistant sand. The quality of the ceramsite is also improved after ceramicization. It can be reused for casting after thermal regeneration, which is energy-saving, environmentally friendly, and has a high added value.
[0022] 3. When the ceramsite of this invention is used in casting, it achieves high heat resistance during the casting process by utilizing the endothermic ceramization reaction of the internal SiO2 and Al2O3 at high temperatures; and the refractory cement selected is resistant to 1500℃, which also gives it excellent heat resistance.
[0023] 4. The main raw material of this invention is foundry dust, which is inexpensive and readily available. This invention utilizes the powdery solid waste from the foundry industry for resource recovery, which is beneficial to environmental protection and has good social and economic benefits. Detailed Implementation
[0024] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.
[0025] Example 1
[0026] A type of high-temperature resistant ceramsite is prepared from raw materials comprising the following weight percentages: 35% calcined ash, 25% bauxite, 25% refractory cement, and 15% water; wherein the calcined ash is the calcined ash discharged together with recycled ash after the incineration of dust-like solid waste generated during the casting process.
[0027] The high-temperature resistant ceramsite provided in this embodiment is prepared using the following steps:
[0028] (1) Add bauxite to the calcined ash and ball mill until the dust particle size is no higher than 1000 mesh to obtain mixture A; (2) Add refractory cement and water that can withstand 1500℃ to mixture A, and stir for 2 minutes using a high-speed mixer with a cylinder speed of 200r / min and a rotor speed of 3000r / min to obtain ceramsite cores; then put the ceramsite cores into a round pot granulator and granulate for 45 minutes to obtain primary ceramsite;
[0029] (3) After the primary ceramsite is naturally oxygenated for 12 hours, it is dried at 65℃ to constant weight. Then the dried primary ceramsite is sieved to obtain primary ceramsite with a particle size of 40 / 200 mesh.
[0030] (4) The selected primary ceramsite is subjected to two-stage low-temperature firing. The first stage firing is carried out at 120℃ for 1.5 hours, and the second stage firing is carried out at 680℃ for 2 hours. Finally, it is cooled to obtain high-temperature resistant ceramsite.
[0031] The ceramsite prepared in this embodiment was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52MPa.
[0032] The test results for the above items are shown in Table 1.
[0033] Example 2
[0034] A type of high-temperature resistant ceramsite is prepared from raw materials comprising the following weight percentages: 50% calcined ash, 20% bauxite, 18% refractory cement, and 12% water; wherein the calcined ash is the calcined ash discharged together with recycled ash after the incineration of dust-like solid waste generated during the casting process.
[0035] The high-temperature resistant ceramsite provided in this embodiment is prepared using the following steps:
[0036] (1) Add bauxite to the calcined ash and ball mill until the dust particle size is no higher than 1000 mesh to obtain mixture A;
[0037] (2) Add refractory cement and water that can withstand 1500℃ to mixture A, and stir for 3 minutes using a high-speed mixer with a cylinder speed of 250r / min and a rotor speed of 3500r / min to obtain ceramsite cores; then put the ceramsite cores into a round pot granulator for granulation for 52 minutes to obtain primary ceramsite.
[0038] (3) After the primary ceramsite is naturally oxygenated for 18 hours, it is dried at 67℃ to constant weight. Then the dried primary ceramsite is sieved to obtain primary ceramsite with a particle size of 40 / 200 mesh.
[0039] (4) The selected primary ceramsite is subjected to two-stage low-temperature firing. The first stage firing is carried out at 125℃ for 1.7h, and the second stage firing is carried out at 710℃ for 2.5h. Finally, it is cooled to obtain high-temperature resistant ceramsite.
[0040] The ceramsite prepared in this embodiment was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52MPa.
[0041] The test results for the above items are shown in Table 1.
[0042] Example 3
[0043] A type of high-temperature resistant ceramsite is prepared from raw materials comprising the following weight percentages: 42% calcined ash, 23% bauxite, 22% refractory cement, and 13% water; wherein the calcined ash is the calcined ash discharged together with recycled ash after the incineration of dust-like solid waste generated during the casting process.
[0044] The high-temperature resistant ceramsite provided in this embodiment is prepared using the following steps:
[0045] (1) Add bauxite to the calcined ash and ball mill until the dust particle size is no higher than 1000 mesh to obtain mixture A;
[0046] (2) Add refractory cement and water that can withstand 1500℃ to mixture A, and use a high-speed mixer with a cylinder speed of 300r / min and a rotor speed of 4000r / min to stir at high speed for 4 minutes to obtain ceramsite cores; then put the ceramsite cores into a round pot granulator and granulate for 60 minutes to obtain primary ceramsite.
[0047] (3) After the primary ceramsite is naturally oxygenated for 24 hours, it is dried at 70℃ to constant weight. Then the dried primary ceramsite is sieved to obtain primary ceramsite with a particle size of 40 / 200 mesh.
[0048] (4) The selected primary ceramsite is subjected to two-stage low-temperature firing. The first stage firing is carried out at 130℃ for 2 hours, and the second stage firing is carried out at 750℃ for 3 hours. Finally, it is cooled to obtain high-temperature resistant ceramsite.
[0049] The ceramsite prepared in this embodiment was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52MPa.
[0050] The test results for the above items are shown in Table 1.
[0051] Example 4
[0052] A type of high-temperature resistant ceramsite is prepared from raw materials comprising the following weight percentages: 35% calcined ash, 25% bauxite, 25% refractory cement, and 15% water; wherein the calcined ash is the calcined ash discharged together with recycled ash after the incineration of dust-like solid waste generated during the casting process.
[0053] The high-temperature resistant ceramsite provided in this embodiment is prepared using the following steps:
[0054] (1) Add bauxite to the calcined ash and ball mill until the dust particle size is no higher than 1000 mesh to obtain mixture A;
[0055] (2) Add refractory cement with a temperature resistance of 1500℃ and water to mixture A. Stir for 2 minutes using a high-speed mixer with a drum speed of 200 r / min and a rotor speed of 3000 r / min to obtain ceramsite cores. Place the ceramsite cores into a round pot granulator and granulate for 45 minutes to obtain primary ceramsite.
[0056] (3) After the primary ceramsite is naturally oxygenated for 12 hours, it is dried at 80℃ to constant weight. Then the dried primary ceramsite is sieved to obtain primary ceramsite with a particle size of 40 / 200 mesh.
[0057] (4) The selected primary ceramsite is subjected to two-stage low-temperature firing. The first stage firing is carried out at 120℃ for 1.5 hours, and the second stage firing is carried out at 680℃ for 2 hours. Finally, it is cooled to obtain high-temperature resistant ceramsite.
[0058] The ceramsite prepared in this embodiment was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52MPa.
[0059] The test results for the above items are shown in Table 1.
[0060] Comparative Example 1
[0061] In this comparative example, refractory cement is not added in step (2), and the remaining raw materials and preparation methods are the same as in Example 1.
[0062] The ceramsite prepared in this comparative example was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52 MPa.
[0063] The test results for the above items are shown in Table 1.
[0064] Comparative Example 2
[0065] In this comparative example, ordinary cement was added in step (2) to replace refractory cement, and the remaining raw materials and preparation methods were the same as in Example 1.
[0066] The ceramsite prepared in this comparative example was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52 MPa.
[0067] The test results for the above items are shown in Table 1.
[0068] Comparative Example 3
[0069] In this comparative example, one of the two low-temperature firing processes in step (4) is firing at 100°C for 1.5 hours, and the remaining raw materials and preparation methods are the same as in Example 1.
[0070] The ceramsite prepared in this comparative example was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52 MPa.
[0071] The test results for the above items are shown in Table 1.
[0072] Comparative Example 4
[0073] In this comparative example, one of the two low-temperature firing processes in step (4) is firing at 150°C for 2 hours, and the remaining raw materials and preparation methods are the same as in Example 1.
[0074] The ceramsite prepared in this comparative example was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52 MPa.
[0075] The test results for the above items are shown in Table 1.
[0076] Comparative Example 5
[0077] In this comparative example, the second stage of the low-temperature firing process in step (4) is firing at 650°C for 2 hours, and the remaining raw materials and preparation methods are the same as in Example 1.
[0078] The ceramsite prepared in this comparative example was tested according to the national standard GB / T17431.2-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods" to determine the pelletizing qualification rate, refractoriness and breakage rate under closed pressure of 52 MPa.
[0079] The test results for the above items are shown in Table 1.
[0080] Table 1. Performance test results of ceramsite in various cases.
[0081]
[0082] As shown in Table 1, the high-temperature resistant ceramsite prepared in the various embodiments of this application can withstand temperatures above 1700℃, and the breakage rate is less than 2.5% under a closing pressure of 52MPa, with a finished product qualification rate of over 90%. By adopting a low-temperature firing method, high-temperature resistant ceramsite with a high finished product qualification rate, high heat resistance, and high compressive strength is obtained while reducing energy consumption.
[0083] Firstly, compared to Example 4 which was dried at 80°C, Example 1, dried at 65°C, showed that the lower drying temperature increased the curing effect of the refractory cement, resulting in better strength of the prepared ceramsite. Secondly, comparing Example 1 with Comparative Examples 1-5, Comparative Example 1 did not add refractory cement, resulting in lower strength and refractoriness of the ceramsite. Comparative Example 2 used ordinary cement instead of refractory cement, resulting in lower strength and refractoriness after firing. Comparative Example 3 had an excessively low first-stage firing temperature, which may have left moisture inside the ceramsite, leading to lower strength. Comparative Example 4 had an excessively high first-stage firing temperature, which, due to the excessively high internal temperature, caused rapid water loss and cracking of the ceramsite. Comparative Example 5 had an excessively low second-stage firing temperature, which prevented some combustibles inside the ceramsite from burning off, thus reducing the refractoriness of the ceramsite.
[0084] This invention improves the compressive strength of expanded clay aggregates by using refractory cement, enabling them to be used for casting core making without high-temperature firing. Low-temperature drying at 65-70℃ prevents the expanded clay aggregates from cracking. Using refractory cement resistant to 1500℃ provides better heat resistance. A two-stage low-temperature firing process—firing at 120-130℃ for 1.5-2 hours and at 680-750℃ for 2-3 hours—burns away combustible materials inside the expanded clay aggregates, achieving high refractoriness and high compressive strength without high-temperature firing. During use, the expanded clay aggregates utilize an endothermic ceramization reaction of SiO2 and Al2O3 within them at the high temperatures of casting, achieving high heat resistance during casting and thus superior performance. This makes them more suitable for heat-resistant sand and allows for reuse in casting after thermal regeneration. Simultaneously, this invention enables high-value secondary utilization of powdered solid waste from the casting industry, significantly reducing energy consumption and production costs in expanded clay aggregate production, resulting in significant social and economic benefits.
[0085] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.
Claims
1. A method of making high temperature resistant ceramsite, characterized by, Includes the following steps: (1) Add bauxite to the calcined ash and ball mill it to obtain mixture A; (2) Add refractory cement and water to mixture A, stir evenly to obtain ceramsite cores, and then granulate to obtain primary ceramsite; (3) Curing, drying and screening of the primary ceramsite; (4) The initial ceramsite after screening is subjected to two-stage low-temperature firing. The first stage firing is carried out at 120-130℃ for 1.5-2 hours, and the second stage firing is carried out at 680-750℃ for 2-3 hours. The calcined ash is the calcined ash that is discharged together with the recycled ash after the dust-like solid waste generated during the casting process is incinerated. The raw materials for the high-temperature resistant ceramsite consist of the following ingredients by weight percentage: 35-50% calcined ash, 20-25% bauxite, 18-25% refractory cement, and 12-15% water.
2. The method of claim 1, wherein the high temperature resistant haydite is prepared by the steps of: In step (1), the particle size of mixture A is no higher than 1000 mesh.
3. The method for preparing high-temperature resistant ceramsite according to claim 1, characterized in that, In step (2), the stirring method is to use a high-speed mixer with a cylinder speed of 200-300 r / min, a rotor speed of 3000-4000 r / min, and a stirring time of 2-4 min.
4. The method of claim 1, wherein the high temperature resistant haydite is prepared by the steps of: In step (2), the granulation method is to use a round pot granulator, and the granulation time is 45-60 minutes.
5. The method of making high temperature resistant haydite according to claim 1, characterized in that, The maintenance method in step (3) is natural maintenance, and the maintenance time is 12-24 hours.
6. The method of making high temperature resistant haydite according to claim 1, characterized in that, The drying temperature in step (3) is 65-70℃.
7. The method of claim 1, wherein the high temperature resistant haydite is prepared by the steps of: The initial ceramsite particles screened in step (3) have a particle size of 40-200 mesh.