CN112777605A - Method for increasing specific surface area of calcined coal series kaolin - Google Patents
Method for increasing specific surface area of calcined coal series kaolin Download PDFInfo
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- CN112777605A CN112777605A CN202110106018.XA CN202110106018A CN112777605A CN 112777605 A CN112777605 A CN 112777605A CN 202110106018 A CN202110106018 A CN 202110106018A CN 112777605 A CN112777605 A CN 112777605A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
- C01B33/40—Clays
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/14—Pore volume
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/16—Pore diameter
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/19—Oil-absorption capacity, e.g. DBP values
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
The invention relates to a method for improving the specific surface area of calcined coal-series kaolin, which adopts the technical scheme that microwave is introduced to perform irradiation in the dehydroxylation process of the coal-series kaolin, and simultaneously, cellosilk with large dielectric constant is added into raw coal-series kaolin in the microwave treatment process to promote the absorption of materials to the microwave, so that the coal-series kaolin is rapidly heated and dehydroxylated in the dehydroxylation stage to promote the rapid reaction of carbon-containing components, realize the in-situ pore-increasing expansion and swelling of the calcined kaolin, and increase the specific surface area and the pore size of the calcined coal-series kaolin, thereby improving the adsorption capacity, particularly the oil absorption performance of the calcined coal-series kaolin. The specific surface area of the coal-series kaolin obtained by the method of the invention reaches 2-3 times of that of the conventional calcined coal-series kaolin, and the oil absorption is improved by 35-45% compared with the common coal-series kaolin clinker.
Description
Technical Field
The invention belongs to the technical field of processing of non-metallic mineral functional materials, and particularly relates to a method for improving the specific surface area of calcined coal series kaolin.
Background
Coal-series kaolin is an important inorganic non-metal clay mineral material, has different purposes after being calcined at different temperatures, is widely applied to dozens of industries such as paper making, coating, ceramics, rubber, chemical industry, medicine, national defense and the like after being calcined, and is mainly applied to the paper making industry. Because of the stable properties of kaolin, kaolin can be used as a filler and a coating material in the paper industry. When the kaolin is used in the papermaking industry, the kaolin can endow paper with good covering performance and excellent glossiness during coating, and in addition, the kaolin can also increase the whiteness and smoothness of the paper and greatly improve the quality of the paper.
With the development of paper making industry in China, the expansion of yield and the introduction of high-speed blade coating machines, the consumption of calcined kaolin is gradually expanded, so that higher requirements are put forward on calcined kaolin. In the fields of paper making and environment, the oil absorption value and whiteness of kaolin are the most important two indexes. The whiteness of the kaolin can be solved by surface coating and controlling the calcining conditions, but the oil absorption value is difficult to increase. At present, the research on oil absorption value in China is less, the oil absorption value of the kaolin in China is generally low and is only about 45g/100g, the oil absorption value of calcined kaolin is also only 60g/100g, the difference is great compared with 90g/100g of the kaolin in the United states, and the index of the oil absorption value becomes one of the important factors restricting the export of the calcined kaolin in China.
In conventional heating methods, heat is transferred through the material by mechanisms of conduction, radiation and convection. In this case, the surface of the material is first heated, after which a temperature gradient is established between the surface of the material and the body, with the temperature being gradually transferred from the surface to the body portion. Compared with the prior art, the microwave is used as a novel heating means, in the heating process, electromagnetic energy is absorbed by the material according to the volume and is converted into heat energy, the temperature transfer in the heating process is replaced by energy conversion, so that the temperature difference does not exist between the surface and the main body, and the temperature field distribution in the material is more uniform. The microwave can penetrate through the material and transfer energy, so that the reaction rate is greatly increased, the energy consumption in the material processing process is reduced, and the microwave can not cause environmental pollution and is applied to the material processing technology. However, in the process of processing kaolin by microwaves, because the kaolin has low microwave absorption rate in the low-temperature process and the heating rate is greatly influenced, the invention uses the fiber filament with high dielectric constant to promote the heating rate of the kaolin in the low-temperature stage, and the fiber filament conducts heat to the kaolin material in the low-temperature stage, thereby accelerating the heating of the material during microwave irradiation and enabling the utilization rate of the microwaves to reach the highest.
Chinese patent CN109748286A discloses a high-whiteness high-oil-absorption-value calcined kaolin and a preparation method thereof, and the method comprises the steps of adding water glass and strong acid into kaolin slurry, controlling the pH value of a reaction system, drying, and calcining to obtain the high-whiteness high-oil-absorption-value calcined kaolin. The method obviously improves the whiteness and oil absorption value of the calcined kaolin, but the treatment by strong acid has certain pollution to the environment. In addition, chinese patent CN108483458A also discloses a method for increasing the specific surface area of kaolin by a wet method, but the process requires the addition of concentrated sulfuric acid, which also causes environmental pollution to some extent, and the process is complicated.
Chinese patent CN101857740A discloses a method for increasing the oil absorption value of calcined kaolin. The method is simple, low in cost and pollution-free, but has high requirement on the purity and granularity of the anhydrous magnesium chloride, otherwise, the excess sieve residues are easy to exceed the standard, certain corrosion is caused on equipment, corrosive gas is generated in the calcining process, the requirement on the equipment is high, and the method is not beneficial to industrial production.
Chinese patent CN108275688A discloses a method for preparing kaolin with high oil absorption, which improves the oil absorption of the product to a certain extent, but adds organic dispersant and intercalation agent in the production process, so that the product has low quality, more impurities and higher cost.
Disclosure of Invention
The invention aims to solve the technical problems that in the prior art, the production process for improving the specific surface area of kaolin has certain corrosivity on equipment due to raw materials, environmental pollution exists, screen residues exceed the standard and the requirement on the equipment is higher, the industrial production is not facilitated, and the quality of products is not high after adding organic dispersing agents, intercalation agents and other additive components in the production process. The method can overcome the technical problems in the prior art, relieve the requirements of the paper industry on the calcined kaolin with high oil absorption value to a certain extent, and has simple working procedures and high oil absorption value of the product. It is another object of the present invention to obtain a calcined coal-based kaolin having a high oil absorption.
The technical scheme of the invention is as follows:
a method for improving the specific surface area of calcined coal-based kaolin comprises the following steps:
1) putting coal series kaolin raw soil and a certain amount of microwave absorption accelerator into a container, and uniformly mixing to obtain a mixed material;
2) placing the container containing the mixed materials into a microwave oven, setting the microwave power at 1500-3000W, and performing microwave treatment for 3-8 min;
3) the mixed material treated by the microwave is transferred into a conventional heating furnace preheated to the same temperature at constant temperature, and is continuously heated to 1000-1200 ℃, the heating rate is 5-8 ℃/min, and the mixed material is cooled to 100 ℃ after being kept warm for a period of time;
4) placing the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal-series kaolin with high specific surface area;
SiO in the coal series kaolin raw soil240-53% of Al2O333-45% of TiO2Content of less than 1%, Fe2O3The content is below 0.90%.
Further, the microwave absorption enhancer is fiber filaments with a dielectric constant not less than 3.6.
Furthermore, the fiber filaments are made of one or more materials of silicon carbide, ferric oxide and graphite.
Further, the heat preservation time in the step 3) is 20min-60 min.
The calcined coal-series kaolin with high oil absorption prepared by the method is characterized in that the specific surface area of the calcined coal-series kaolin with high oil absorption is 30-40m2The total pore volume of the single-point adsorption is 0.10-0.15cm3The per gram, the average adsorption pore diameter is 10-15 nm.
Further, the calcined coal-series kaolin with high oil absorption has an oil absorption value of not less than 80g/100 g.
The method adopts the method of rapid temperature rise in the dehydroxylation stage of the coal-series kaolin, so that the coal-series kaolin is rapidly dehydroxylated in the dehydroxylation process, the rapid reaction of carbon-containing components is promoted, the in-situ pore-increasing and puffing of the calcined coal-series kaolin are realized, and the specific surface area and the pore size of the calcined coal-series kaolin are increased.
The method plays an auxiliary calcination role of microwave, and obtains a calcined coal-series kaolin sample with high specific surface area through the combined action of the microwave and a conventional heating furnace.
The invention adds a fiber yarn to promote the microwave absorption efficiency of kaolin raw soil in the microwave treatment process, the fiber yarn can be any metal material or inorganic non-metal material with the dielectric constant larger than 3.6, the fiber yarn prepared from silicon carbide, ferric oxide and graphite is adopted for experiment, and the fiber yarn is conveniently separated from a kaolin sample after the microwave irradiation is finished.
Detailed Description
The coal-series kaolin used in the embodiments of the invention comprises the following chemical components: SiO 2242.684% of Al2O336.717% TiO20.934% of Fe2O3The content was 0.429%.
Example 1:
(1) mixing 3g of coal-series kaolin raw material and 1.5g of fiber yarns made of silicon carbide and putting the mixture into a container;
(2) placing the container filled with kaolin crude soil into a microwave oven to be treated for 7min under the microwave of 1800W;
(3) putting the coal-series kaolin pretreated by the microwave in the step (2) into a heating furnace preheated to the same temperature at constant temperature, continuously heating to 1000 ℃, keeping the temperature at 5 ℃/min, keeping the temperature for 20min, and cooling to 100 ℃;
(4) and putting the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal series kaolin product with high specific surface area.
Example 2:
(1) mixing 5g of coal-series kaolin raw material with 2.5g of fiber yarns made of graphite, and putting the mixture into a container;
(2) placing the container filled with kaolin crude soil into a microwave oven, and treating for 5min under 2500W microwave;
(3) putting the coal-series kaolin pretreated by the microwave in the step (2) into a heating furnace which is preheated to the same temperature at constant temperature, putting the coal-series kaolin which is preheated to the same temperature into the heating furnace which is preheated to the same temperature at constant temperature, continuously heating to 1100 ℃, keeping the temperature for 60min, and cooling to 100 ℃;
(4) and putting the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal series kaolin product with high specific surface area.
Example 3:
(1) mixing 4g of coal-series kaolin raw soil and 2g of fiber yarns made of ferric oxide, and putting the mixture into a container;
(2) placing the container filled with kaolin crude soil into a microwave oven, and treating for 3min under 2000W microwave;
(3) and (3) putting the coal-series kaolin pretreated by the microwave in the step (2) into a heating furnace preheated to the same temperature at constant temperature, continuously heating to 1050 ℃, keeping the temperature for 30min, and cooling to 100 ℃.
(4) And putting the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal series kaolin product with high specific surface area.
Example 4:
(1) mixing 6g of coal-series kaolin raw soil and 3g of fiber yarns made of silicon carbide, and putting the mixture into a container;
(2) placing the container filled with kaolin crude soil into a microwave oven, and treating for 6min under 2800W microwave;
(3) putting the coal-series kaolin pretreated by the microwave in the step (2) into a heating furnace preheated to the same temperature at constant temperature, continuously heating to 1200 ℃, keeping the temperature at 6 ℃/min, keeping the temperature for 40min, and cooling to 100 ℃;
(4) and putting the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal series kaolin product with high specific surface area.
The main BET parameters and oil absorption value data of the calcined coal-series kaolin products having high specific surface areas obtained in examples 1 to 4 of the present invention are shown in table 1.
Comparative example 1:
the BET parameters and oil absorption data of the common coal series kaolin clinker samples are shown in Table 1.
Comparative example 2:
comparative example 2 is a calcined coal series kaolin product obtained by directly treating a common coal series kaolin clinker sample with a heating furnace, and the specific method comprises the following steps:
(1) mixing 3g of coal-series kaolin raw material and 1.5g of fiber yarns made of silicon carbide, and putting the mixture into a container;
(2) immediately putting the container with the materials into a heating furnace, heating the container from room temperature to 1000 ℃, keeping the temperature for 20min, and cooling the container to 100 ℃;
(3) and (3) putting the sample obtained in the step (2) into a dryer, and continuously cooling to room temperature to obtain the calcined coal-series kaolin product.
TABLE 1
As can be seen from Table 1, the specific surface area of the sample after microwave irradiation is far greater than that of the sample directly treated by a common heating furnace, because the coal-series kaolin is rapidly heated in the dehydroxylation stage in the microwave treatment stage, the rapid reaction of the carbon-containing components in the coal-series kaolin is promoted, and the coal-series kaolin is subjected to swelling action, so that the specific surface area and the adsorption average pore size of the calcined coal-series kaolin are increased. The calculation result shows that the specific surface area of the calcined coal-series kaolin treated by the method disclosed by the invention is 2-3 times that of the conventional calcined coal-series kaolin, and the oil absorption value is improved by 35-45% compared with that of a sample treated by a common heating furnace.
Claims (6)
1. A method for improving the specific surface area of calcined coal-based kaolin comprises the following steps:
1) putting coal series kaolin raw soil and a certain amount of microwave absorption accelerator into a container, and uniformly mixing to obtain a mixed material;
2) placing the container containing the mixed materials into a microwave oven, setting the microwave power at 1500-3000W, and performing microwave treatment for 3-8 min;
3) the mixed material treated by the microwave is transferred into a conventional heating furnace preheated to the same temperature at constant temperature, and is continuously heated to 1000-1200 ℃, the heating rate is 5-8 ℃/min, and the mixed material is cooled to 100 ℃ after being kept warm for a period of time;
4) placing the calcined kaolin sample cooled to 100 ℃ into a dryer to be continuously cooled to room temperature, thus obtaining the calcined coal-series kaolin with high specific surface area;
SiO in the coal series kaolin raw soil240-53% of Al2O333-45% of TiO2Content of less than 1%, Fe2O3The content is below 0.90%.
2. The method of claim 1, wherein the calcined coal-based kaolin has a specific surface area that is increased by: the microwave absorption accelerant is fiber yarn with dielectric constant not less than 3.6.
3. The method for increasing the specific surface area of calcined coal-based kaolin under the microwave-assisted action according to claim 2, wherein: the fiber filaments are made of one or more materials of silicon carbide, ferric oxide and graphite.
4. The method of claim 1, wherein the calcined coal-based kaolin has a specific surface area that is increased by: the heat preservation time in the step 3) is 20min-60 min.
5. The high oil absorption calcined coal-based kaolin prepared by the method of claim 1, wherein the high oil absorption calcined coal-based kaolin has a specific surface area of 30 to 40m2The total pore volume of the single-point adsorption is 0.10-0.15cm3The per gram, the average adsorption pore diameter is 10-15 nm.
6. A high oil absorption calcined coal-based kaolin prepared according to the method of claim 1, wherein the high oil absorption calcined coal-based kaolin has an oil absorption of not less than 80g/100 g.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0131785A2 (en) * | 1983-07-14 | 1985-01-23 | Georgia Kaolin Company, Inc. | Processing of kaolinitic clays at high solids under acidic conditions |
| CN1915814A (en) * | 2006-09-12 | 2007-02-21 | 内蒙古蒙西高岭粉体股份有限公司 | Technique of fluidized instant calcinations of kaolin in coal series |
| CN102491356A (en) * | 2011-11-30 | 2012-06-13 | 唐山麦迪逊高岭土有限公司 | Preparation method of calcined kaolin with high oil absorption |
| CN108905957A (en) * | 2018-06-22 | 2018-11-30 | 成都新柯力化工科技有限公司 | A method of building decoration specific surface area of diatomite is improved using microwave |
| CN110577225A (en) * | 2019-09-23 | 2019-12-17 | 山西金宇科林科技有限公司 | Preparation method of high-whiteness calcined kaolin with ultrahigh oil absorption |
| WO2019246082A1 (en) * | 2018-06-18 | 2019-12-26 | Basf Corporation | Methods of preparation and utilization of bauxitic kaolins |
| CN110844914A (en) * | 2019-12-08 | 2020-02-28 | 太原理工大学 | Method for improving specific surface area of coal-series kaolin under synergistic effect of ultrasonic microwaves |
-
2021
- 2021-01-26 CN CN202110106018.XA patent/CN112777605B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0131785A2 (en) * | 1983-07-14 | 1985-01-23 | Georgia Kaolin Company, Inc. | Processing of kaolinitic clays at high solids under acidic conditions |
| CN1915814A (en) * | 2006-09-12 | 2007-02-21 | 内蒙古蒙西高岭粉体股份有限公司 | Technique of fluidized instant calcinations of kaolin in coal series |
| CN102491356A (en) * | 2011-11-30 | 2012-06-13 | 唐山麦迪逊高岭土有限公司 | Preparation method of calcined kaolin with high oil absorption |
| WO2019246082A1 (en) * | 2018-06-18 | 2019-12-26 | Basf Corporation | Methods of preparation and utilization of bauxitic kaolins |
| CN108905957A (en) * | 2018-06-22 | 2018-11-30 | 成都新柯力化工科技有限公司 | A method of building decoration specific surface area of diatomite is improved using microwave |
| CN110577225A (en) * | 2019-09-23 | 2019-12-17 | 山西金宇科林科技有限公司 | Preparation method of high-whiteness calcined kaolin with ultrahigh oil absorption |
| CN110844914A (en) * | 2019-12-08 | 2020-02-28 | 太原理工大学 | Method for improving specific surface area of coal-series kaolin under synergistic effect of ultrasonic microwaves |
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