Columnar granular activated carbon preparation process adopting multifunctional belt type microwave activation furnace and biomass columnar granular activated carbon thereof

Abstract

According to the columnar granular activated carbon preparation process adopting the multifunctional belt type microwave activation furnace, activated carbon is prepared through a post-forming method, compatibility and stability of raw materials are optimized through a multi-stage heating mode, shape and size consistency of the activated carbon is ensured through granulation equipment, and the columnar granular activated carbon is prepared through a microwave radiation heating process. Under a static state without an activating agent, non-differentiated efficient activation of a semi-finished product is realized, the activation uniformity and quality uniformity of the activated carbon are ensured, and pollution-free continuous production is realized. The invention also provides biomass columnar granular active carbon which has high specific surface area, excellent adsorption performance, mechanical strength and durability after being activated by a multifunctional belt type microwave activation furnace, and has wide application prospects in the fields of air purification, solvent recovery, liquid decolorization, catalyst loading, organic gas protection, waste gas treatment, water purification industry and the like.

Description

Technical Field

Background Art

[0003] Currently, traditional activated carbon activation processes usually use rotary kilns or Slep furnace. However, for the semi-finished products activated by these processes, an activating agent needs to be added, and a series of cumbersome treatments such as recovery, rinsing, dehydration drying and baking are required. Multi-step operations are likely to introduce impurities, and may also damage the original pore structure of the activated carbon, reducing its adsorption performance, thus affecting the product quality. In addition, the wastewater, waste gas and waste residue generated during the treatment process may also cause environmental pollution.

Summary of the Invention

[0005] A preparation process of columnar granular activated carbon using a multifunctional belt-type microwave activation furnace includes the following steps: S1. Raw material preparation: While stirring with a magnetic stirrer, slowly add the carbonized carbon powder into the binder until the addition of the carbon powder is completed to obtain a mixture, and perform secondary heating and kneading stirring on the mixture through an internally heated kneading mixer to obtain the raw material; S2. Molding and granulation: Prepare the raw material obtained in step S1 into a strip-shaped semi-finished product through a hydraulic granulation device, naturally dry the strip-shaped semi-finished product, then dry it, and make it into columnar particles of a specific length to obtain a columnar semi-finished product; S3. Carbon activation: Activate the columnar semi-finished product obtained in step S2 through a preheated belt-type microwave activation furnace, and rapidly cool it through water cooling after activation to obtain a rough product; S4. Sieving: Sieve the rough product obtained in step S3 through a sieve plate to obtain the biomass columnar granular activated carbon.

[0006] At present, traditional activated carbon activation processes usually use rotary kilns or Slep furnace, and for the semi-finished products after activation, an activating agent needs to be added, followed by a series of cumbersome processes such as recovery, rinsing, dewatering, air drying, and drying. For example, when phosphoric acid is used as the activating agent and the raw materials are chemically activated, a large amount of solid pyrophosphoric acid will be contained in the semi-finished products. Usually, hot water and steam at 80-120°C are required to dissolve and dilute the residual phosphoric acid in the activated semi-finished product particles for recovery. Through 3-5 times of steaming and rinsing, all the residual phosphoric acid is cleaned, that is, the pH value reaches above 3.5-5, and then it is air dried, dried, and screened.

[0007] The present invention prepares columnar granular activated carbon by a post-forming method. First, through a magnetic stirrer, the raw materials are ensured to be evenly mixed, and the mixture is secondarily heated, kneaded, and stirred by an internally heated kneading mixer to optimize the compatibility and stability of the raw materials, laying a good foundation for subsequent forming and granulation. Second, through a hydraulic granulation device for forming and granulation to ensure the consistency of the shape and size of the activated carbon. Third, the semi-finished products are efficiently activated by a microwave radiation heating process without an activating agent, realizing rapid and uniform heating and activation of the materials. By using a belt-type microwave activation furnace instead of a rotary kiln or Slep furnace, the semi-finished products can be carbon-activated in a stationary state, avoiding the surface damage problem caused by mutual friction of the materials during movement in the traditional activation method; at the same time, it is equipped with an intelligent system to monitor and accurately control the activation temperature and activation time in real time, ensuring the uniformity of activated carbon activation and quality uniformity, and realizing continuous production. Finally, through water-cooled rapid cooling treatment, the burnout rate can be effectively reduced, the yield can be increased, and the re-adsorption of moisture and organic substances in the air can be prevented.

[0008] Among them, the belt-type microwave activation furnace is one of a mesh belt-type microwave activation furnace and a steel belt-type microwave activation furnace.

[0009] Preferably, the feeding end and the discharging end of the belt-type microwave activation furnace adopt a sealing device composed of nitrogen and a multi-layer isolation curtain for oxygen isolation protection, thus preventing external air from entering the furnace and preventing the products in the furnace from catching fire and burning; the discharging and cooling section of the belt-type microwave activation furnace adopts a structure in which multiple water-cooling jackets are spliced into a return shape and can quickly cool the high-temperature materials after activation, and under the independent adjustment and control of the water inlet valve, the outlet water temperature is controlled at 50-60°C.

[0010] Preferably, the carbon powder in step S1 is one of chemically prepared biomass carbon powder, physically prepared coal-based carbon powder, bamboo carbon powder, and coconut shell carbon powder; the binder is one or a combination of more than one of attapulgite powder, bentonite, diatomite, humic acid, sodium humate, potassium humate, CMC, and phenolic resin.

[0011] First, the carbon powder is subjected to high-temperature carbonization treatment, and its particle structure is stable. Then, the carbonized carbon powder and the binder are combined and formed. On the basis of maintaining the original pore structure, a stronger particle structure can be formed, improving the mechanical strength and stability of the finished product, preparing activated carbon products with more uniform particle sizes and more consistent properties, and meeting the requirements for product quality in different application fields. Second, by optimizing the combination of binders, the binding force between carbon powder particles can be improved, and the negative impact on the pore structure can be reduced; the inorganic binder provides a skeleton support, and the organic binder enhances the viscosity and toughness of the binder, making the surface strength of the carbon particles higher and the uniformity better, thereby enhancing the surface strength and acid, alkali, and high-temperature resistance of the activated carbon, and improving the adaptability of the semi-finished activated carbon after forming to high-temperature carbon activation conditions.

[0012] Preferably, the preparation method of the binder described in step S1 includes the following steps: A1. Preheating: Pour an appropriate amount of water into a container and heat it to 80°C. A2. Feeding: Add the binder to the container described in step A1 at a stirring speed of 120 r / min. After the addition is completed, adjust the stirring speed to 240 r / min until the liquid in the container is completely uniform visually, and set aside.

[0013] In the present invention, through preheating and staged stirring, the binder can be more uniformly dispersed in water to form a stable and uniform binder solution, so as to improve the subsequent binding effect with the carbon powder and reduce the possible caking or unevenness during the forming process.

[0014] Preferably, the heating temperature of the secondary heating kneading and stirring described in step S1 is 60 - 75°C, and the stirring time is 25 - 30 min.

[0015] In the present invention, the raw materials are subjected to a primary heating treatment through the preparation of the binder, and the heating temperature is 80°C, which provides an ideal basis for the subsequent mixing with the carbon powder. Then, the mixture is subjected to secondary heating kneading and stirring by an internal heating kneading mixer, and the heating temperature is 60 - 75°C, optimizing the compatibility and stability of the raw materials and laying a good foundation for the subsequent forming and granulation. Among them, the two heating temperatures are similar, which can ensure that the binder is always in an appropriate temperature state during the preparation and mixing processes, avoiding the negative impact on the raw materials caused by the sharp temperature change, and thus ensuring the consistency and high performance of the final product.

[0016] Preferably, the die aperture of the granulation equipment described in step S2 is 2 - 2.5 mm or 4 - 4.5 mm.

[0017] Specifically, the granulation equipment is one of a hydraulic granulator or a screw extruder.

[0018] Preferably, the drying temperature in step S2 is 90 - 120°C, and the moisture content of the strip semi-finished product is ≤25 - 30%. More preferably, the specific length in step S2 is 4 - 9 mm.

[0019] By optimizing the forming and granulation conditions, and precisely controlling the drying temperature and the moisture content of the strip semi-finished product, the present invention avoids the problems of over-drying or over-wetting of the semi-finished product during the drying process, and at the same time provides an ideal humidity condition for the subsequent carbon activation process, which helps the uniform development of the pore structure and the improvement of the adsorption performance.

[0020] Preferably, the temperature of the preheating section of the belt-type microwave activation furnace in step S3 is set at 300°C, and the temperature of the activation section is set at 700 - 750°C.

[0021] First, the present invention uses microwave radiation heating to activate the activated carbon. When polar substance molecules (such as water molecules, organic substances, etc.) in the activated carbon are in the microwave electromagnetic field, these molecules will be induced to produce dipole rotational polarization phenomena and convert microwave energy into heat energy, which is transmitted to the columnar granular activated carbon in the furnace through the microwave transmission system. Under the action of microwave energy, the internal and surface temperatures of the activated carbon rise rapidly, activating the surface functional groups of the activated carbon and optimizing the pore structure, thereby achieving rapid and uniform activation of the activated carbon. During the microwave radiation heating process, some organic substances in the activated carbon are decomposed into CO 2 gas and water vapor. These gases generate vapor pressure inside the activated carbon and are released from the inside of the raw material to the outside, causing a significant porous structure to form inside, thereby increasing the specific surface area of the activated carbon. At high temperatures, the residual carbon in the activated carbon reacts with water vapor in the water-gas reaction, which can further expand the pore volume.

[0022] Secondly, the material is slowly heated to the temperature range required for activation through the preheating section, avoiding thermal shock to the material caused by rapid temperature changes, and thus protecting the structure and performance of the material; through the activation section, an appropriate reaction temperature is provided to promote the expansion and connection of pores, increase the proportion of mesopores and macropores, and improve the adsorption capacity of the activated carbon for macromolecular substances. At the same time, the problems of material sintering or performance degradation that may be caused by too high a temperature are avoided.

[0023] Preferably, the running speed of the conveyor belt of the belt-type microwave activation furnace in step S3 is 5 - 10 mm / min, and the material thickness is 10 mm.

[0024] The present invention ensures sufficient residence time of the material in the activation section through the running speed of the conveyor belt, thereby optimizing the activation effect, improving the activation efficiency and the consistency of product quality; by controlling the material thickness, it ensures that the microwave can uniformly penetrate the material and heat it, avoiding problems of local overheating or insufficient heating.

[0025] Preferably, the gas pressure in the activation section of the belt-type microwave activation furnace described in step S3 is 0.1 - 0.2 MPa, the gas flow rate is 10 mL / min, and the gas temperature ≥ 120 °C; the activation time described in step S3 is 90 - 180 min.

[0026] Specifically, the gas is one of steam or nitrogen, and is used for activation protection.

[0027] The present invention can promote the development of pore structure and the formation of surface functional groups by precisely controlling the gas pressure, flow rate, and temperature, thereby providing a suitable reaction environment, promoting the activation reaction, and improving the specific surface area, pore volume, and adsorption performance of the activated carbon.

[0028] Another object of the present invention is to provide a biomass columnar granular activated carbon.

[0029] The biomass columnar granular activated carbon prepared by the columnar granular activated carbon preparation process using the multifunctional belt-type microwave activation furnace.

[0030] The present invention proposes a preparation process for columnar granular activated carbon using a multifunctional belt-type microwave activation furnace, and uses the post-forming method to prepare activated carbon. First, through a magnetic stirrer, ensure uniform mixing among raw materials, and perform secondary heating, kneading, and stirring on the mixture through an internally heated kneading mixer to optimize the compatibility and stability of the raw materials, laying a good foundation for subsequent forming and granulation. Second, perform forming and granulation through granulation equipment to ensure the consistency of the shape and size of the activated carbon. Third, perform high-efficiency activation on the semi-finished product through microwave radiation heating technology to achieve rapid and uniform heating of the material. Replace the rotary kiln or Slep furnace with a belt-type microwave activation furnace, enabling the semi-finished product to be carbon-activated in a stationary state, avoiding the surface damage problem caused by material movement in the traditional activation method; at the same time, cooperate with an intelligent system to monitor and precisely control the activation temperature and activation time in real time, ensuring the activation uniformity and quality uniformity of the activated carbon, and realizing continuous production. Finally, through water-cooled rapid cooling treatment, the burnout rate can be effectively reduced and the yield can be increased.

[0031] The present invention also proposes a biomass columnar granular activated carbon, which has a high specific surface area, excellent adsorption performance, mechanical strength, and durability, and has broad application prospects in the fields of air purification, solvent recovery, liquid decolorization, catalyst loading, organic gas protection, waste gas treatment, and water purification industries, providing an efficient solution for industrial production and environmental protection.

Specific Embodiments

[0033] Example 1: A preparation process of columnar granular activated carbon using a multifunctional belt-type microwave activation furnace, comprising the following steps: S1. Raw material preparation: While stirring with a magnetic stirrer, slowly add 500 g of carbonized chemically prepared biomass carbon powder to the binder until the addition of the carbon powder is complete, obtaining a mixture. Using an internally heated kneading mixer, perform secondary heating, kneading, and stirring on the mixture at 65 °C for 30 min to obtain the raw material. S2. Molding and granulation: Using a hydraulic granulation device, prepare the raw material described in step S1 into a strip-shaped semi-finished product. Naturally dry the strip-shaped semi-finished product, then dry it at 120 °C until the moisture content ≤ 25 - 30%, and form columnar particles of a specific length to obtain a columnar semi-finished product. S3. Carbon activation: Activate the columnar semi-finished product described in step S2 at a speed of 5 mm / min for 180 min using a preheated belt-type microwave activation furnace. After activation, rapidly cool it by water cooling to obtain a rough finished product. S4. Sieving: Sieve the rough finished product described in step S3 through a 12-mesh sieve plate to obtain biomass columnar granular activated carbon.

[0034] Example 2: A preparation process of columnar granular activated carbon using a multifunctional belt-type microwave activation furnace, comprising the following steps: S1. Raw material preparation: While stirring with a magnetic stirrer, slowly add 500 g of carbonized physically prepared coal-based carbon powder to the binder until the addition of the carbon powder is complete, obtaining a mixture. Using an internally heated kneading mixer, perform secondary heating, kneading, and stirring on the mixture at 65 °C for 30 min to obtain the raw material. S2. Molding and granulation: Using a hydraulic granulation device, prepare the raw material described in step S1 into a strip-shaped semi-finished product. Naturally dry the strip-shaped semi-finished product, then dry it at 120 °C until the moisture content ≤ 25 - 30%, and form columnar particles of a specific length to obtain a columnar semi-finished product. S3. Carbon activation: Activate the columnar semi-finished product described in step S2 at a speed of 5 mm / min for 180 min using a preheated belt-type microwave activation furnace. After activation, rapidly cool it by water cooling to obtain a rough finished product. S4. Sieving: Sieving the crude product described in step S3 through a 12-mesh sieve plate to obtain biomass columnar granular activated carbon.

[0035] Example 3: A preparation process of columnar granular activated carbon using a multifunctional belt-type microwave activation furnace, comprising the following steps: S1. Raw material preparation: While stirring with a magnetic stirrer, slowly add 500 g of carbonized coconut shell carbon powder to the binder until the addition of the carbon powder is completed to obtain a mixture. Then, perform secondary heating and kneading and stirring on the mixture at 65°C for 30 min using an internally heated kneading and stirring machine to obtain the raw material; S2. Molding and granulation: Using a hydraulic granulation device, prepare the raw material described in step S1 into a strip-shaped semi-finished product. Air-dry the strip-shaped semi-finished product naturally, and then dry it at 120°C until the moisture content ≤ 25 - 30%, and form columnar particles of a specific length to obtain a columnar semi-finished product; S3. Carbon activation: Activate the columnar semi-finished product described in step S2 at a speed of 5 mm / min for 180 min using a preheated belt-type microwave activation furnace, and rapidly cool it by water cooling after activation to obtain a crude product; S4. Sieving: Sieving the crude product described in step S3 through a 12-mesh sieve plate to obtain biomass columnar granular activated carbon.

[0036] Comparative Example 1: A preparation process of columnar activated carbon by first molding using a rotary kiln, comprising the following steps: S1. Raw material preparation: Screen and dry the wood chips until the moisture content is 15 - 20%. After the wood chips are dried, grind the wood chips into 120 meshes using a grinding machine and set aside; S2. Preparation of phosphoric acid solution: Dilute the phosphoric acid solution with a content of 85% with clean water to obtain a phosphoric acid solution with a content of 56% and set aside; S3. Mixing and stirring: Using a double-screw mixer, initially mix and stir the wood chips described in step S1 and the 56% phosphoric acid solution described in step S2 in a ratio of 2:1 for 15 min to obtain a primary mixture, and then load the primary mixture into a kneading and stirring machine for secondary kneading and stirring for 30 min until the two are fully mixed and uniform to obtain a mixture; S4. First molding, then carbonization and activation: Using a hydraulic press, granulate the mixture described in step S3 to obtain a semi-finished product. Feed the columnar particles into a carbonization rotary kiln for carbonization at 250 - 300°C, and then feed them into an activation rotary kiln for activation at 550 - 650°C to obtain a crude product; S5, Phosphoric acid recovery: Use hot water and steam to cook and rinse the crude product described in step S4 until the pH value reaches above 3.5 - 5, air dry, bake, screen and remove ash to obtain chemically produced wood columnar activated carbon.

[0037] Comparative Example 2: A preparation process for producing columnar activated carbon by pre - forming in a rotary kiln, comprising the following steps: S1, Raw material preparation: Grind coal into 150 - mesh powder using a pulverizer, and set aside; S2, Mixing and stirring: Use a plow - type mixer to initially mix and stir the coal powder described in step S1 and coal tar at a ratio of 1:0.4 for 18 minutes to obtain a primary mixture, and then send the primary mixture into a kneading and stirring machine for secondary kneading and stirring for 30 minutes until the two are fully mixed evenly to obtain a mixture; S3, Forming: Use a hydraulic press to granulate the mixture described in step S2, and air dry naturally to obtain a semi - finished product; S4, Carbonization and activation: Send the semi - finished product described in step S3 into a carbonization rotary kiln for carbonization at 250 - 300 °C, and then send it into a Slep furnace for high - temperature activation at 850 - 1100 °C to obtain a crude product S5, Screening and ash removal: After the crude product described in step S4 cools, perform screening and ash removal to obtain physically produced wood columnar activated carbon.

[0038] Table 1 Test data table of Examples 1 - 3 and Comparative Example 1

[0039] As can be seen from Table 1, compared with Comparative Example 1 using an activator and an activation rotary kiln, the biomass columnar granular activated carbon prepared in Examples 1 - 3 has a high specific surface area, excellent adsorption performance, mechanical strength and durability; compared with Comparative Example 2 using a Slep furnace, the biomass columnar granular activated carbon prepared in Examples 1 - 3 has a high specific surface area, excellent adsorption performance, mechanical strength and durability.

[0040] The preparation method of the present invention prepares activated carbon by post-forming method. Through multi-stage heating, the compatibility and stability of raw materials are optimized, laying a good foundation for subsequent forming and granulation. The forming and granulation are carried out by hydraulic granulation equipment to ensure the consistency of the shape and size of the activated carbon. Through the microwave radiation heating process, without the need for an activator in a static state, the high-efficiency activation of the semi-finished product is realized without difference, ensuring the activation uniformity and quality uniformity of the activated carbon, and realizing pollution-free continuous production. By using a belt-type microwave activation furnace instead of a rotary kiln or a Slep furnace, the semi-finished product can be carbon-activated in a static state, avoiding the surface damage problem caused by the movement of materials in the traditional activation method. At the same time, it is equipped with an intelligent system to monitor and accurately control the activation temperature and activation time in real time, ensuring the activation uniformity and quality uniformity of the activated carbon and realizing continuous production. Finally, through water-cooled rapid cooling treatment, the burn-off rate can be effectively reduced and the yield can be increased.

[0041] The biomass columnar granular activated carbon prepared by the present invention has broad application prospects in the fields of air purification, solvent recovery, liquid decolorization, catalyst loading, organic gas protection, waste gas treatment and water purification industry, etc., providing an efficient solution for industrial production and environmental protection.

[0042] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace, characterized in that: The following steps are involved: S1. Raw material preparation: slowly adding carbonized carbon powder into the binder while stirring by a magnetic stirrer until the addition of the carbon powder is completed to obtain a mixture, and performing secondary heating, kneading and stirring on the mixture by an internal heating kneading stirrer to obtain a raw material; S2, forming and granulating: forming the raw materials prepared in step S1 by hydraulic granulating equipment to obtain a strip-shaped semi-finished product, air-drying the strip-shaped semi-finished product naturally, drying it, and forming it into columnar particles of a specific length to obtain a columnar semi-finished product; S3, carbon activation: activating the columnar semi-finished product in step S2 by a preheated belt microwave activation furnace, and rapidly cooling it by water cooling after activation to obtain a crude finished product; S4, sieving: sieving the coarse finished product in step S3 through a sieve plate to obtain biomass columnar granular activated carbon.

2. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: In step S1, the carbon powder is one of chemical biomass carbon powder, physical coal carbon powder, bamboo charcoal powder, and coconut shell carbon powder; the adhesive is one or more combinations of convexocarbon powder, bentonite, diatomaceous earth, humic acid, sodium humate, potassium humate, CMC, and phenolic resin.

3. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 2, characterized in that: The method for preparing the adhesive in step S1 comprises the following steps: A1. Preheating: Pour an appropriate amount of water into a container and heat to 80°C; A2. Adding materials: Add the adhesive to the container described in step A1 at a stirring speed of 120 r / min. After the addition is completed, adjust the stirring speed to 240 r / min until the liquid in the container is visually completely uniform and set aside.

4. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: The heating temperature of the secondary heating, kneading and stirring in step S1 is 60-75° C., and the stirring time is 25-30 min.

5. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: The mold aperture of the granulation equipment in step S2 is 2-2.5 mm or 4-4.5 mm.

6. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: The drying temperature in step S2 is 90-120° C., and the moisture content of the strip-shaped semi-finished product is ≤25-30%.

7. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: In step S3, the temperature of the preheating section of the belt microwave activation furnace is set to 300°C, and the temperature of the activation section is set to 700-750°C.

8. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: In step S3, the conveyor belt of the belt microwave activation furnace runs at a speed of 5-10 mm / min, and the material thickness is 10 mm.

9. The process for preparing columnar granular activated carbon using a multifunctional belt microwave activation furnace according to claim 1, characterized in that: The gas pressure in the activation section of the belt microwave activation furnace in step S3 is 0.1-0.2 MPa, the gas flow rate is 10 mL / min, and the gas temperature is ≥120° C.; the activation time in step S3 is 90-180 min.

10. Biomass columnar granular activated carbon prepared by the columnar granular activated carbon preparation process using a multifunctional belt microwave activation furnace as described in any one of claims 1 to 9.

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