A physical method for preparing high-strength, high-ignition-point columnar activated carbon from palm shells

Abstract

This invention discloses a physical method for preparing high-strength, high-ignition-point columnar activated carbon from palm shells. The process involves washing away surface grease and lime from the screened thick portion of palm shells with a sodium carbonate solution, carbonizing it under a steam atmosphere, then coarsely crushing, screening, and pulverizing to obtain carbonized powder. Distilled vegetable tar is used as a binder to granulate the powder into columnar particles, which are then carbonized and activated to obtain high-strength, high-ignition-point columnar activated carbon. This method utilizes sodium carbonate solution to soak the palm shells, which does not damage the physical properties of the raw materials and the residues do not affect the final product indicators. The palm shells are carbonized under a steam atmosphere, resulting in stronger affinity between the carbonized material and the binder. Furthermore, the mechanical action of coarse crushing of the carbonized material removes impurities from the surface that affect product strength. The vegetable tar undergoes low-temperature distillation, which removes irritating odor components and increases tar viscosity, making it suitable as a binder. The production process has low odor and produces a high-strength product.

Description

Technical Field

[0001] This invention relates to the fields of environmental protection technology and activated carbon processing technology, and in particular to a physical method for preparing high-strength, high-ignition-point columnar activated carbon from palm shells. Background Technology

[0002] Plant-based physical activated carbon typically uses coconut shells and bamboo as raw materials. Coconut shells offer the best performance but are more expensive. Bamboo, due to its high potassium content, directly affects the ignition point of the activated carbon, setting it at 320-350℃. Wood-based activated carbon, due to its inherent characteristics, produces low-strength, lightweight activated carbon unsuitable for physical methods.

[0003] Palm shells are classified as a byproduct in the palm fruit processing chain, with a huge output, and the main products in the processing are crude palm oil and palm oil. Because palm shells themselves have low value, they have long been discarded as waste in the palm fruit processing chain, with some palm kernel shells only used as an alternative energy source for coal. Due to the variety of palm shell types and uneven shell wall thickness, a large amount of quicklime is added during the palm oil production process. Most of this quicklime adheres to the palm shells; if it is directly used to prepare columnar activated carbon without treatment, it will reduce the product's strength and result in excessively high ash content. Currently, there are no successful cases of using palm shells to produce physical columnar activated carbon. This invention, however, can successfully produce physical columnar activated carbon from palm shells, with a carbon tetrachloride adsorption rate ≥60%, strength ≥97%, and ignition point >400℃.

[0004] In addition, the binders used in most commercially available physically processed columnar activated carbon are coal tar and coal pitch, which are non-renewable resources. However, biomass raw materials such as bamboo, wood, and fruit shells produce large amounts of plant tar during the carbonization process. This tar has a strong odor and is not widely used, resulting in a severe resource surplus. Utilizing this tar would be a valuable renewable resource. However, plant tar has low viscosity, and when used directly as a binder in columnar activated carbon, the resulting activated carbon has low strength. Therefore, there are very few physically processed columnar activated carbon products on the market that use plant tar as a binder. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a reliable, widely available, environmentally friendly, and high-performance physical method for preparing high-strength, high-ignition-point columnar activated carbon from palm shells.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows:

[0007] A method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method, comprising:

[0008] After screening, the palm shell raw material is soaked in sodium carbonate solution and then filtered. It is then soaked and filtered in water, and the water soaking process is repeated a preset number of times to obtain a washed material. After drying, the washed material is carbonized and kept warm in a steam atmosphere for a preset time to obtain a carbonized material. The carbonized material is coarsely crushed, screened, and pulverized to obtain carbonized material powder. The carbonized material powder is then mixed with starch and distilled vegetable tar, and water is added for kneading. The mixture is then shaped into columnar materials. Finally, the columnar materials are carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon.

[0009] As one possible implementation method, this scheme further involves passing the palm shell raw material through a 3-mesh sieve, and then soaking the palm shell raw material with a mesh larger than 3 mesh alternately with sodium carbonate solution and water.

[0010] As one possible implementation, the mass concentration of the sodium carbonate solution in this scheme is 1-10%, and the soaking time of the palm shell raw material in sodium carbonate solution and water is 1 hour per soaking; wherein, after the palm shell raw material is soaked and filtered in sodium carbonate solution, the soaking and filtration in water is repeated 4 times; the moisture content of the washed material after drying is controlled within 15%.

[0011] As one possible implementation, the washed material is dried and then carbonized at an ambient temperature of 450–650°C for 10–120 minutes in a steam atmosphere to obtain carbonized material.

[0012] As one possible implementation, the carbonized material in this scheme is further coarsely crushed by a double-roll crusher with a spacing of 3-6 mm, then screened to obtain carbonized material with a particle size greater than 1.5 mm, and then pulverized to obtain carbonized material powder.

[0013] As one possible implementation, the amount of starch added in this scheme is 1 to 4% of the weight of the carbonized powder, and the amount of distilled vegetable tar added is 25 to 40% of the weight of the carbonized powder.

[0014] As a preferred implementation option, the distilled vegetable tar described in this scheme is preferably a tar byproduct produced during the carbonization process of bamboo, wood, fruit shells, etc., and is obtained by low-temperature distillation at a temperature of 160-240℃.

[0015] As one possible implementation, this scheme further involves mixing carbonized material powder with starch and distilled vegetable tar, and then adding water for kneading. First, the mixture is granulated into columnar materials with a diameter of φ6-10mm using a hydraulic press. Then, it is granulated and shaped again to form columnar materials with a diameter of φ2-5mm. Finally, the columnar materials are carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon.

[0016] As a preferred implementation option, the carbonization temperature of the columnar material in this scheme is 450-650℃, and the holding time is 10-60 min; the activation temperature of the water vapor atmosphere is 850-950℃, and the holding time is 30-120 min.

[0017] As a preferred implementation option, this solution preferably includes the following steps:

[0018] (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh;

[0019] (2) Soaking and washing: Soak the palm shell raw material obtained by screening in step (1) in a sodium carbonate solution with a mass concentration of 1-10% for 1 hour and then filter it; then soak it in water for 1 hour and filter it. Repeat the soaking and filtration process more than 4 times to obtain the washing material.

[0020] (3) Drying and carbonization: After drying the washing material to a moisture content of less than 15%, place it in a steam atmosphere and carbonize it at 450-650℃ for 10-120 minutes to obtain carbonized material.

[0021] (4) Crushing and screening: The carbonized material is coarsely crushed by a double roller crusher with a spacing of 3-6mm, then screened to obtain carbonized material with a particle size greater than 1.5mm, and then crushed to obtain carbonized material powder.

[0022] (5) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated by a hydraulic press to form columnar material with a diameter of φ6-10mm. After that, it is granulated and molded again to form columnar material with a diameter of φ2-5mm. The amount of starch added is 1-4% of the weight of the carbonized material powder, and the amount of distilled vegetable tar added is 25-40% of the weight of the carbonized material powder.

[0023] (6) Carbonization and activation: The columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon; wherein, the carbonization temperature of the columnar material is 450~650℃ and the holding time is 10~60min; the ambient temperature for steam atmosphere activation is 850~950℃ and the holding time is 30~120min.

[0024] In this solution, thin palm shells can be removed from the raw materials during screening.

[0025] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0026] (1) This method uses palm shells as raw materials, specifically palm shells after oil extraction. The white ash adhering to the surface of the palm shells after oil extraction is coated and adhered to by the grease, making it difficult to remove. Treatment with strong alkalis or acids would damage the physical properties of the palm shell material itself, and the residual alkalis and acids would corrode equipment and affect granulation strength in subsequent processes. Therefore, this method utilizes sodium carbonate solution soaking. The sodium carbonate solution can wash away the white ash and grease from the palm shells after oil extraction, removing impurities that affect the strength of the prepared columnar activated carbon, without damaging the physical properties of the palm shell material. The residue does not affect the product indicators of the columnar activated carbon and is non-corrosive to equipment.

[0027] (2) In this scheme, the palm shell is carbonized in a water vapor atmosphere, which makes the palm shell carbonized material have a stronger affinity with the binder. At the same time, the carbonized material is coarsely crushed. The mechanical action of crushing is used to remove impurities and fine powders on the surface of the carbonized material that affect the strength of columnar activated carbon and screen them out.

[0028] (3) The distilled vegetable tar used in this scheme is distilled at low temperature, which can remove most of the light components with irritating odors, while increasing the viscosity of the vegetable tar. As a binder for columnar activated carbon, the production process has less odor and the strength of the prepared columnar activated carbon is improved. Furthermore, the higher the distillation temperature, the higher the specific gravity of the prepared columnar activated carbon.

[0029] (4) In preparing columnar activated carbon, this scheme uses secondary granulation technology to produce columnar material, which can improve the strength and specific gravity of columnar activated carbon. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment discloses a method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method, which includes the following steps:

[0033] (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh;

[0034] (2) Soaking and washing: Soak the palm shell raw material obtained by screening in step (1) in a 5% sodium carbonate solution for 1 hour and then filter it; then soak it in water for 1 hour and filter it. Repeat the soaking and filtering process 4 times to obtain the washing material.

[0035] (3) Drying and carbonization: After drying the washing material to a moisture content of less than 15%, place it in a steam atmosphere and carbonize it at 500℃ for 20 minutes to obtain carbonized material.

[0036] (4) Crushing and screening: The carbonized material is coarsely crushed by a double roller crusher with a spacing of 3-6mm, then screened to obtain carbonized material with a particle size greater than 1.5mm, and then crushed to obtain carbonized material powder.

[0037] (5) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated into columnar material with a diameter of φ9mm using a hydraulic press. After granulation and molding again, it is made into columnar material with a diameter of φ4mm. The amount of starch added is 2% of the weight of the carbonized material powder, and the amount of distilled vegetable tar is 33% of the weight of the carbonized material powder obtained by low-temperature distillation at 200℃.

[0038] (6) Carbonization and activation: The columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon; wherein, the carbonization temperature of the columnar material is 500℃ and the holding time is 20min; the ambient temperature for steam atmosphere activation is 900℃ and the holding time is 60min.

[0039] In this embodiment, the palm shell physical method columnar activated carbon obtained showed no obvious signs of powder shedding on its surface after activation.

[0040] Example 2

[0041] This embodiment discloses a method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method, which includes the following steps:

[0042] (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh;

[0043] (2) Soaking and washing: Soak the palm shell raw material obtained by screening in step (1) in a 1% sodium carbonate solution for 1 hour and then filter it; then soak it in water for 1 hour and filter it. Repeat the soaking and filtration process 4 times to obtain the washing material.

[0044] (3) Drying and carbonization: After drying the washing material to a moisture content of less than 15%, it is placed in a steam atmosphere and carbonized at 450℃ for 120 minutes to obtain carbonized material.

[0045] (4) Crushing and screening: The carbonized material is crushed by a double roller crusher with a spacing of 3-6mm, then screened to obtain carbonized material with a particle size greater than 1.5mm, and then crushed to obtain carbonized material powder.

[0046] (5) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated into columnar material with a diameter of φ10mm using a hydraulic press. After granulation and molding again, it is made into columnar material with a diameter of φ5mm. The amount of starch added is 4% of the weight of the carbonized material powder, and the amount of distilled vegetable tar is 25% of the weight of the carbonized material powder obtained by low-temperature distillation at 240℃.

[0047] (6) Carbonization and activation: The columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon; wherein, the carbonization temperature of the columnar material is 450℃ and the holding time is 60min; the ambient temperature for steam atmosphere activation is 850℃ and the holding time is 120min.

[0048] In this embodiment, the palm shell physical method columnar activated carbon obtained showed no obvious signs of powder shedding on its surface after activation.

[0049] Example 3

[0050] This embodiment discloses a method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method, which includes the following steps:

[0051] (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh;

[0052] (2) Soaking and washing: Soak the palm shell raw material obtained by screening in step (1) in a 10% sodium carbonate solution for 1 hour and then filter it; then soak it in water for 1 hour and filter it. Repeat the soaking and filtration process 4 times to obtain the washing material.

[0053] (3) Drying and carbonization: After drying the washing material to a moisture content of less than 15%, place it in a steam atmosphere and carbonize it at 650℃ for 10 minutes to obtain carbonized material.

[0054] (4) Crushing and screening: The carbonized material is coarsely crushed by a double roller crusher with a spacing of 3-6mm, then screened to obtain carbonized material with a particle size greater than 1.5mm, and then crushed to obtain carbonized material powder.

[0055] (5) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated into columnar material with a diameter of φ6mm using a hydraulic press. After granulation and molding again, it is made into columnar material with a diameter of φ2mm. The amount of starch added is 1% of the weight of the carbonized material powder, and the amount of distilled vegetable tar is 40% of the weight of the carbonized material powder obtained by low-temperature distillation at 160℃.

[0056] (6) Carbonization and activation: The columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon; wherein, the carbonization temperature of the columnar material is 650℃ and the holding time is 10min; the ambient temperature for steam atmosphere activation is 950℃ and the holding time is 30min.

[0057] In this embodiment, the palm shell physical method columnar activated carbon obtained showed no obvious signs of powder shedding on its surface after activation.

[0058] Comparative Example

[0059] This comparative example describes a method for preparing columnar activated carbon from palm shells using a physical method, which includes the following steps:

[0060] (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh;

[0061] (2) Drying and carbonization: The palm shell raw material is placed in a steam atmosphere and carbonized at 500℃ for 20 minutes to obtain carbonized material;

[0062] (3) Crushing and screening: The carbonized material is coarsely crushed by a double roller crusher with a spacing of 3-6mm, then screened to obtain carbonized material with a particle size greater than 1.5mm, and then crushed to obtain carbonized material powder;

[0063] (4) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated into columnar material with a diameter of φ9mm using a hydraulic press. After granulation and molding again, it is made into columnar material with a diameter of φ4mm. The amount of starch added is 2% of the weight of the carbonized material powder, and the amount of distilled vegetable tar is 33% of the weight of the carbonized material powder obtained by low-temperature distillation at 200℃.

[0064] (5) Carbonization and activation: The columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon; wherein, the carbonization temperature of the columnar material is 500℃ and the holding time is 20min; the ambient temperature for steam atmosphere activation is 900℃ and the holding time is 60min.

[0065] In this comparative example, the palm shell columnar activated carbon prepared by physical method showed significant and severe powder depletion on its surface after activation.

[0066] Comparative Test

[0067] To facilitate performance testing and comparison of the palm shell-based physical method columnar activated carbon prepared in this embodiment and comparative example, carbon tetrachloride adsorption rate, particle strength, ignition point, and apparent density were tested on the columnar activated carbon prepared in Examples 1, 2, 3, and the comparative example according to the following standards: "Test Methods for Determination of Carbon Tetrachloride Adsorption Rate (Activity) of Wood-based Activated Carbon" (GB / T 12496.5-1999), "Test Methods for Determination of Apparent Density of Wood-based Activated Carbon" (GB / T 12496.1-1999), "Test Methods for Ignition Point of Activated Carbon" (GB / T 20450-2006), and "Test Methods for Determination of Strength of Coal-based Granular Activated Carbon" (GB / T 7702.3-2008). The results are as follows:

[0068]

[0069] Note: The higher the activation level of columnar activated carbon (the higher the carbon tetrachloride adsorption rate), the lower its strength and specific gravity. For example, if the activation level of the comparative sample is increased to a carbon tetrachloride adsorption rate of 60%, the strength will be less than 85.34%.

[0070] As can be seen from the above comparison, the columnar activated carbon prepared by this method has excellent strength and high ignition point.

[0071] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method, characterized in that, It includes: After the palm shell raw material is sieved, it is soaked in sodium carbonate solution and then filtered dry. Then it is soaked in water and filtered dry. The water soaking process is repeated a preset number of times to obtain the washing material. After the washed material is dried, it is carbonized and kept warm in a steam atmosphere for a preset time to obtain carbonized material. The carbonized material is coarsely crushed, sieved, and pulverized to obtain carbonized material powder. Then, the carbonized material powder is mixed with starch and distilled vegetable tar, and water is added for kneading. Then, it is shaped and processed to obtain columnar material. Finally, the columnar material is carbonized and activated in a steam atmosphere to obtain high-strength, high-ignition-point palm shell physical method columnar activated carbon.

2. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that, The process of sieving the palm shell raw material involves passing the palm shell raw material through a 3-mesh sieve to obtain coarse and thick palm shell raw material with particles larger than 3 mesh.

3. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that... The sodium carbonate solution has a mass concentration of 1-10%, and the soaking time of the palm shell raw material in sodium carbonate solution and water is 1 hour per soaking. The palm shell raw material is soaked and filtered in sodium carbonate solution, and the soaking and filtration in water is repeated 4 times. The moisture content of the washed material after drying is controlled to be below 15%.

4. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that, After the washed material is dried, it is carbonized in a steam atmosphere at an ambient temperature of 450-650℃ for 10-120 minutes to obtain carbonized material.

5. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that, The carbonized material is coarsely crushed by a double-roll crusher with a spacing of 3-6 mm, then screened to obtain carbonized material with a particle size greater than 1.5 mm, and then pulverized to obtain carbonized material powder.

6. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that, The amount of starch added is 1-4% of the weight of the carbonized powder, and the amount of distilled vegetable tar added is 25-40% of the weight of the carbonized powder.

7. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 6, characterized in that, The distilled vegetable tar is a tar byproduct produced during the carbonization process of bamboo, wood, and fruit shells. It is obtained by low-temperature distillation at a temperature of 160-240℃.

8. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 1, characterized in that, When carbonized powder is mixed with starch and distilled vegetable tar, and then water is added for kneading, the mixture is first granulated into columnar material with a diameter of φ6-10mm using a hydraulic press. Then, it is granulated and processed into columnar material with a diameter of φ2-5mm. After carbonization and activation in a steam atmosphere, high-strength, high-ignition-point palm shell physical method columnar activated carbon is obtained.

9. The method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using physical methods as described in claim 8, characterized in that, The carbonization temperature of the columnar material is 450–650℃, and the holding time is 10–60 min; the activation temperature of the steam atmosphere is 850–950℃, and the holding time is 30–120 min.

10. A method for preparing high-strength, high-ignition-point palm shell columnar activated carbon using a physical method as described in any one of claims 1 to 9, characterized in that: It includes the following steps: (1) Raw material screening: The palm shell raw material is passed through a 3-mesh sieve to obtain coarse and thick palm shell raw material with a mesh size greater than 3 mesh; (2) Soaking and washing: Soak the palm shell raw material after screening in step (1) in a sodium carbonate solution with a mass concentration of 1~10% for 1 hour and then filter it; then soak it in water for 1 hour and filter it. Repeat the soaking and filtration process 4 times to obtain the washing material. (3) Drying and carbonization: After drying the washing material to a moisture content of less than 15%, place it in a steam atmosphere and carbonize it at 450-650℃ for 10-120 minutes to obtain carbonized material; (4) Crushing and screening: The carbonized material is coarsely crushed by a double roller crusher with a spacing of 3-6 mm, then screened to obtain carbonized material with a particle size greater than 1.5 mm, and then crushed to obtain carbonized material powder; (5) Granulation and molding: After the carbonized material powder is mixed evenly with starch and distilled vegetable tar, an appropriate amount of water is added and kneaded. Then, the mixture is granulated into columnar material with a diameter of φ6-10mm using a hydraulic press. After that, it is granulated again to form columnar material with a diameter of φ2-5mm. The amount of starch added is 1-4% of the weight of the carbonized material powder, and the amount of distilled vegetable tar added is 25-40% of the weight of the carbonized material powder. (6) Carbonization and activation: After carbonization and activation in a steam atmosphere, high-strength, high-ignition-point palm shell physical method columnar activated carbon is obtained; wherein, the carbonization temperature of the columnar material is 450~650℃ and the holding time is 10~60min; the ambient temperature for activation in a steam atmosphere is 850~950℃ and the holding time is 30~120min.

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