CN1193842C - Process for preparing mullite-type snad for precision casting by calcining coal-series kaolinite - Google Patents
Process for preparing mullite-type snad for precision casting by calcining coal-series kaolinite Download PDFInfo
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- CN1193842C CN1193842C CN 02108814 CN02108814A CN1193842C CN 1193842 C CN1193842 C CN 1193842C CN 02108814 CN02108814 CN 02108814 CN 02108814 A CN02108814 A CN 02108814A CN 1193842 C CN1193842 C CN 1193842C
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- calcination
- kaolinite
- mullite
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Abstract
The present invention relates to a method for preparing mullite-type sand for precision casting by calcining coal-series kaolinite. Mineral of which the kaolinite content is larger than 90% is selected as raw material for crushing, sieving into sand material of 10 to 80 meshes; the sand material is conveyed into a rotary kiln for calcination; the calcination temperature is 1100DEG. C to 1500DEG. C; the calcination time is one to four hours. The shaping and the foreign matter removal can be carried for the product after calcination; the products are sieved into the products with various difference specifications after the shaping and the foreign matter. The present invention has the advantages of power consumption reduction, the abrasion of device material reduction, short calcination time, low product cost, good particle shape of the product, high content of mullite phase, high fireproof degree, less low-melting material content, etc.
Description
Technical Field
The invention relates to a production method of fine casting sand powder, in particular to a production method of mullite sand powder for calcination and precision castingof coal series kaolinite rock.
Background
The mullite sand powder is widely used in the precision casting industry as a shell making material for investment casting. According to the traditional process method, a shaft kiln is adopted to calcine coal series kaolinite rock blocks into flint clay after 72 hours, because the lumpiness is small, heat flow exchange can be prevented, and the calcining temperature is difficult to increase, the feed material has large lumpiness generally at 1200-1300 ℃, the calcining time is as long as 72 hours, and the phenomenon of under burning is easy to generate, the flint clay is generated after the calcination, the flint clay is secondarily crushed into 0.18-1 mm sand grains from the lumpiness of more than 50mm, because the primary crushing particle size distribution is unreasonable, secondary crushing is needed, and the crushed particles are respectively sieved out by a 4-layer screen, namely a high-frequency vibration screen, and are 10-16 meshes, 16-30 meshes, 30-60 meshes and 60-80 meshes. Removing impurities to obtain a product, and calcining to improve the hardness of the raw material from 3-4 (Mohs) to 7-8 (Mohs), so that the crushing hammer head and the sieve bar are seriously damaged and need to be frequently replaced, the crushing power consumption and the equipment material abrasion are increased, and the production efficiency and the continuous production time are restricted; meanwhile, because the flint clay basically contains no water, a large amount of dust is generated in the crushing and screening processes, and the environmental protection treatment cost is increased; and the impurity content and the powder content of the product are easy to exceed the standard, the yield is unstable, and the large-scale production is difficult to form.
Technical content
In order to solve the defects in the traditional process, the invention provides the production method for calcining the mullite type precision casting sand powder by the coal series kaolinite, which has short calcination time, reduces the crushing power consumption and the equipment material abrasion, and ensures that the calcined product is easy to finish and mold.
The technical scheme of the invention is as follows: a production method for calcining mullite type precision casting sand powder by coal series kaolinite comprises the steps of selecting minerals with the kaolinite content of more than 90 percent as raw materials, crushing the raw materials for production, grading the raw materials into sand materials with the grain size of-10 to 80 meshes in a closed air flow mode, feeding the sand materials into a rotary kiln for calcination, wherein the calcination temperature is 1100-1500 ℃, the calcination time is 1-4 hours, and shaping and removing impurities from the products after calcination. After shaping and impurity removal, screening the mixture into products with different specifications of 10-16 meshes, 16-30 meshes, 30-60 meshes and 60-80 meshes.
According to the invention, the raw materials are firstly crushed and then calcined, so that the power consumption and the equipment material abrasion are reduced, the calcination time is shortened, the production cost of the product is averagely reduced by 1/3, the input-output ratio is high, the yield is improved by 4 times compared with the yield produced by the traditional process, the product particle shape is good, the screening efficiency after shaping and impurity removal is improved by 3-4 times compared with the traditional process, the mullite phase in the product is high, the refractoriness is high, low-melting substances are reduced, the impurity content is reduced, and particularly, the phenomenon ofcracking and shell leakage of a formwork manufactured by using the product after high-temperature calcination.
Detailed Description
The present invention will be further described with reference to the following examples.
A process for preparing the mullite-type precision-cast sand powder from coal-series kaolinite includes such steps as crushing the ore whose content of kaolinite is greater than 90%, classifying in enclosed airflow classifier, collecting the fine particles of minus 80 meshes in cyclone dust collector and bag-type dust collector, sieving the particles of plus 80 meshes in 10 meshes, returning the particles of plus 10 meshes back to crusher, calcining in direct-burning rotary kiln at 1100-1500 deg.C for 1-4 hr, depolymerizing, shaping, removing sharp edges, removing impurities, removing iron dregs, and screening into various products of 10-16 meshes, 16-30 meshes, 30-60 meshes and 60-80 meshes, wherein the screening efficiency can be improved by 3-4 times after shaping and impurity removal. The product prepared according to the invention is characterized in that: the grain shape is good, the content of miscellaneous powder is particularly low, calculated by PPm, the content is greatly lower than 0.3 percent of the upper limit of the precision casting industry standard, the prepared investment pattern reduces the cracking and shell leakage tendency, the investment pattern is sent to the national refractory material quality supervision and inspection test center for testing, the mullite phase is 60 percent, the refractoriness is higher than 1790 ℃, the refractoriness is higher than 55 percent of the precision casting industry standard, and the manufacturing cost of the product is reduced by one third on average.
The calcining reaction process of the coal-series kaolinite rock is as follows:
when the calcination temperature is 400-650 ℃, the endothermic reaction is carried out, and the reaction formula is as follows:
hydroxyl water removal method for kaolinite metakaolinite
When the calcination temperature is 900-1000 ℃, the exothermic reaction is carried out, and the reaction formula is as follows:
alumino-silica spinel cristobalite
When the calcination temperature is 1000-1100 ℃, the exothermic reaction is carried out, and the reaction formula is as follows:
mullite-like cristobalite
When the calcination temperature is 1100-1500 ℃, the exothermic reaction is carried out, and the reaction formula is as follows:
mullite cristobalite
During the calcination process, a small amount of organic matter (carbon, etc.) in the coal-series kaolinite rock forms carbon dioxide to escape.
Claims (2)
1. A production method for calcining mullite type precision casting sand powder by coal series kaolinite selects minerals with the kaolinite content of more than 90 percent as raw materials, firstly crushes the raw materials for production, divides the raw materials into sand materials with minus 10 to plus 80 meshes in a closed air flow classification mode, sends the sand materials into a rotary kiln for calcination, the calcination temperature is 1100 to 1500 ℃, the calcination time is 1 to 4 hours, and shapes and removes impurities from the products after calcination.
2. The production method of the coal-series kaolinite calcination mullite type precision casting sand powder as claimed in claim 1, is characterized in that: and screening the reshaped and impurity-removed mullite into products with various specifications.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02108814 CN1193842C (en) | 2002-04-08 | 2002-04-08 | Process for preparing mullite-type snad for precision casting by calcining coal-series kaolinite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02108814 CN1193842C (en) | 2002-04-08 | 2002-04-08 | Process for preparing mullite-type snad for precision casting by calcining coal-series kaolinite |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1382539A CN1382539A (en) | 2002-12-04 |
| CN1193842C true CN1193842C (en) | 2005-03-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02108814 Expired - Fee Related CN1193842C (en) | 2002-04-08 | 2002-04-08 | Process for preparing mullite-type snad for precision casting by calcining coal-series kaolinite |
Country Status (1)
| Country | Link |
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| CN (1) | CN1193842C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105798223A (en) * | 2016-03-23 | 2016-07-27 | 刘建荣 | Technology for casting molding sand through coal gangue |
| CN117550617B (en) * | 2023-12-29 | 2024-07-16 | 安徽金岩高岭土新材料股份有限公司 | Technology for preparing mullite by taking coal-series kaolinite as raw material |
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2002
- 2002-04-08 CN CN 02108814 patent/CN1193842C/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| CN1382539A (en) | 2002-12-04 |
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Effective date of registration: 20160317 Address after: 235000, Anhui City, Huaibei province economic development to Longhu Industrial Park, 26 Dragon Road Patentee after: Anhui banket kaolin Science and Technology Ltd. Address before: 235000 Anhui city of Huaibei province Phelex Road No. 219 Patentee before: Jinyan Kaolinite Development Co Ltd, Huaibei |
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| C56 | Change in the name or address of the patentee | ||
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Address after: 235000, No. 26, long road, Longhu Industrial Park, Huaibei Economic Development Zone, Anhui, China Patentee after: Anhui banket kaolin Science and Technology Ltd. Address before: 235000, Anhui City, Huaibei province economic development to Longhu Industrial Park, 26 Dragon Road Patentee before: Anhui banket kaolin Science and Technology Ltd. |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20050323 Termination date: 20210408 |