阅读说明：本技术 一种分级磨粉分级混捏制备高性能活性炭的方法 (Method for preparing high-performance activated carbon by classified milling and classified kneading ) 是由 李小龙 魏进超 杨本涛 戴波 李俊杰 于 2020-05-11 设计创作，主要内容包括：一种分级磨粉分级混捏制备高性能活性炭的方法,该方法包括：1)将活性原料、低粘结性原料和粘结剂混合磨粉,然后加入辅料进行一级强力混捏,得到一级混捏料；2)将高粘结性原料和粘结剂混合磨粉,然后加入辅料,并与一级混捏料混合进行二级强力混捏,得到二级混捏料；3)将二级混捏料挤压成型,得到活性炭前驱体成型料；4)将活性炭前驱体成型料进行干燥,得到干燥料；5)将干燥料进行炭化活化反应,得到高性能活性炭。本发明采用分级磨粉可改善不同粘结性碳原料与粘结剂的混合粘结性能和界面结合效果,采用分级混捏可改善低粘结性原料与高粘结性原料结合的亲和性和粘结力,并使得高、低粘结性原料与粘结剂混合效果更好,产品性能更加稳定。(A method for preparing high-performance activated carbon by classified milling and classified kneading comprises the following steps: 1) mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material; 2) mixing and grinding the high-cohesiveness raw material and the binder, adding the auxiliary material, mixing with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material; 3) extruding and molding the secondary kneaded material to obtain an active carbon precursor molding material; 4) drying the active carbon precursor molding material to obtain a dried material; 5) and carrying out carbonization and activation reaction on the dried material to obtain the high-performance activated carbon. The invention can improve the mixing adhesive property and the interface bonding effect of different adhesive carbon raw materials and adhesives by adopting graded milling, can improve the binding affinity and the binding power of low-adhesive raw materials and high-adhesive raw materials by adopting graded kneading, and can ensure that the mixing effect of the high-adhesive raw materials and the low-adhesive raw materials and the adhesives is better and the product performance is more stable.)

1. A method for preparing high-performance activated carbon by classified milling and classified kneading comprises the following steps:

1) milling and first-stage kneading: mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material;

2) milling and secondary kneading: mixing and grinding the high-cohesiveness raw material and the binder, adding the auxiliary material, mixing with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material;

3) and (3) molding and granulating: extruding and molding the secondary kneaded material to obtain an active carbon precursor molding material;

4) and (3) drying: drying the active carbon precursor molding material to obtain a dried material;

5) and (3) heat treatment: and carrying out carbonization and activation reaction on the dried material to obtain the high-performance activated carbon.

2. The method of claim 1, wherein: the method further comprises the following steps:

6) cooling and screening: cooling and screening the high-performance activated carbon subjected to heat treatment to obtain large-particle high-performance activated carbon;

7) and (3) recycling: and (3) returning the small-particle activated carbon obtained after cooling and screening as an active raw material to the step 1) for reuse.

3. The method according to claim 1 or 2, characterized in that: in step 1), still include the addition of metal ore among crocus and the first order kneading process, specifically do: mixing and grinding the active raw material, the low-viscosity raw material and the binder, adding the metal ore into the ground powder, mixing the ground powder and the metal ore, and then adding the auxiliary material into the mixture to perform primary strong kneading to obtain a primary kneaded material;

preferably, the metal ore is an iron-containing ore; preferably one or more of iron manganese ore, iron copper ore, iron titanium ore and iron tungsten ore; the proportion of the addition of the metal ore to the addition of all the carbon raw materials is a; wherein: 0 < a.ltoreq.15%, preferably 0.1% < a.ltoreq.10%, more preferably 0.5% < a.ltoreq.8%.

4. The method according to any one of claims 1-3, wherein: the binder is a non-asphalt-based binder or an asphalt-based binder; and/or

The content of the binder mixed with the high-cohesiveness raw material in the step 2) is 0-80%, preferably 3-55%, and more preferably 5-30% of the content of the binder mixed with the low-cohesiveness raw material in the step 1).

5. The method according to any one of claims 1-4, wherein: the auxiliary materials are a forming agent and water; preferably, the forming agent is one or more of coal tar, carboxymethyl cellulose, polyvinyl alcohol and sesbania powder; and/or

The content of the forming agent in the auxiliary material added in the step 2) is 0-90%, preferably 5-70%, and more preferably 10-50% of the content of the forming agent in the auxiliary material added in the step 1).

6. The method according to any one of claims 3-5, wherein: the mass percentage of each raw material in the secondary kneaded material obtained in the step 2) is as follows: 0-70 parts of active raw materials, 15-50 parts of low-cohesiveness raw materials, 15-50 parts of high-cohesiveness raw materials, 3-15 parts of binders, 7-20 parts of forming agents and 0-15 parts of metal ores.

7. The method according to any one of claims 1-6, wherein: the active raw material in the step 1) is one or more of active carbon powder, active carbon production crushed material and waste powdered active carbon; and/or

The caking index of the low-caking-property raw material is less than or equal to 5; preferably, the low-cohesiveness raw material is one or two of coke powder and fly ash; and/or

The caking index of the high-caking-property raw material in the step 2) is more than 5; preferably, the high-caking raw material is one or more of coking coal, bituminous coal and anthracite.

8. The method according to any one of claims 1-7, wherein: the grinding is to grind each raw material respectively until more than 90% of the raw material passes through 200 meshes, preferably more than 95% of the raw material passes through 200 meshes, and more preferably more than 97% of the raw material passes through 200 meshes; or

The milling is to mill each raw material to 70% or more, preferably 75% or more, and more preferably 80% or more, through 325 mesh.

9. The method according to any one of claims 1-8, wherein: the heat treatment in the step 5) is specifically as follows: adding the dried material into a carbonization furnace for carbonization to obtain a carbonized material; then adding the carbonized material into an activation furnace, and introducing water vapor or carbon dioxide into the activation furnace to perform an activation reaction with the carbonized material to obtain high-performance activated carbon;

preferably, in the carbonization process, the concentration of CO in the carbonization furnace is controlled; preferably, the concentration of CO in the carbonization furnace is controlled to be b by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of a heat source of the carbonization furnace, wherein: b is more than 0 and less than or equal to 45 percent, preferably more than 0.1 percent and less than or equal to 40 percent, and more preferably more than 0.5 percent and less than or equal to 37 percent; the temperature range of carbonization is 300-900 ℃, preferably 400-850 ℃, and more preferably 500-800 ℃; the carbonization time is 15-180 min, preferably 20-120 min, and more preferably 30-90 min; and/or

Introducing mixed gas of water vapor and oxygen or introducing mixed gas of carbon dioxide and oxygen into the activation furnace in the activation reaction process; preferably, the volume fraction of the oxygen amount in the mixed gas in the water vapor amount or the carbon dioxide amount is 0.1-5%, preferably 0.3-4%, and more preferably 0.5-3%; the temperature range of the activation reaction is 700-1100 ℃, preferably 800-1000 ℃, and more preferably 850-950 ℃; the time of the activation reaction is 20-240 min, preferably 30-180 min, and more preferably 40-120 min.

10. The method according to any one of claims 1-8, wherein: the heat treatment in the step 5) is specifically as follows: adding the dried material into a carbonization-activation integrated furnace, and simultaneously introducing water vapor or carbon dioxide to the furnace end of the carbonization-activation integrated furnace to perform carbonization-activation reaction with the dried material to obtain high-performance activated carbon;

preferably, during the heat treatment process of the carbonization and activation integration, the concentration of CO in the furnace is controlled; preferably, the concentration of CO in the carbonization-activation integrated furnace is controlled to be c by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of the heat source of the carbonization-activation integrated furnace, wherein: c is more than 0 and less than or equal to 42 percent, preferably more than 0.1 percent and less than or equal to 37 percent, and more preferably more than 0.5 percent and less than or equal to 35 percent;

preferably, the temperature range of the heat treatment is 500-1100 ℃, preferably 600-1000 ℃, and more preferably 650-950 ℃; the time of the heat treatment is 15-240 min, preferably 20-180 min, and more preferably 30-120 min.

11. The method according to any one of claims 1-10, wherein: the primary strong kneading and/or the secondary strong kneading are/is carried out by adopting an intermittent stirrer, a continuous stirrer or a strong mixer for strong mixing, and preferably, the strong mixer is adopted; preferably, the kneading process is carried out with heat tracing, wherein the heat tracing temperature is 50-100 ℃, and preferably 70-90 ℃;

preferably, the degree of mixing of the first-stage kneaded material and/or the second-stage kneaded material is 75% or more, preferably 80% or more, and more preferably 85% or more.

12. The production method according to any one of claims 1 to 11, characterized in that: the shape of the active carbon precursor molding material in the step 3) is one or more of spherical, cylindrical and rectangular; preferably, the shape of the active carbon precursor molding material is cylindrical, and the size of the cylindrical active carbon precursor molding material is 4-12 mm, preferably 4.5-11 mm, and more preferably 5-10 mm; and/or

In the step 4), the active carbon precursor molding material is dried until the water content is lower than 13%, preferably lower than 10%, and more preferably lower than 7%.

Technical Field

The invention relates to a preparation method of activated carbon for flue gas desulfurization and denitrification, in particular to a method for preparing high-performance activated carbon by grinding, grading and kneading in a grading manner, and belongs to the technical field of activated carbon preparation.

Background

As is well known, the dry technique of activated carbon can jointly remove SO₂、NO_xThe method has the characteristics of high desulfurization and denitrification efficiency and high byproduct recycling utilization rate, has obvious advantages compared with a wet method or a semi-dry method, and is widely applied to the fields of sintering, coking, waste incineration and the like in recent years. Meanwhile, the dry activated carbon technology exposes the problems of uneven quality of the activated carbon, unstable quality of the same batch and the like, and further popularization and application of the dry activated carbon technology are influenced to a certain extent. Therefore, the quality of the activated carbon is a key to the influence of the activated carbon dry process technology.

The quality of the activated carbon is related to the preparation method of the activated carbon. Among various methods for preparing activated carbon, the technology for preparing activated carbon for desulfurization and denitrification of sintering flue gas by a coal blending method has been widely applied. Chinese patent CN 109250713A discloses a process for producing desulfurization and denitrification activated carbon, which comprises the steps of mixing and grinding coking coal and coke powder according to a specific proportion, then adding a certain proportion of coal tar and water, carrying out heat preservation and heating for kneading, feeding the coal tar and the water which are added into a hydraulic press after the coal tar and the water are fully infiltrated, permeated and uniformly dispersed with the coal powder, and extruding into a fixed wet carbon finished product by using a certain mold under a certain pressure. Wherein the addition ratio of the coal tar is 13-23%. And after the qualified carbon strips are naturally dried and aired, carbonizing the qualified carbon strips by using a carbonization furnace according to the property requirements of different activated carbon, and activating the carbonized materials by using an activation furnace to finally obtain the desulfurization and denitrification activated carbon meeting different physicochemical property requirements. The method produces qualified molded products, but the addition amount of the coal tar is large, the production cost is high, and the obtained products have low wear resistance and are easy to fluctuate.

Many raw materials adopted in the existing process for preparing the activated carbon are low-caking raw materials (such as coke powder), high-caking raw materials (such as main coking coal and bituminous coal) and asphalt, the raw materials are ground into powder and then mixed with coal tar and water, and the pulverized powder is kneaded, granulated, dried, carbonized, activated and the like to prepare the activated carbon. In order to ensure the smooth forming process or the qualified index performance of the final activated carbon product, the addition ratio of the binding agent or forming agent such as coal tar or pitch is usually high, which results in high cost. Meanwhile, because of the difference of the adhesive property of the raw materials, the mixed adhesive effect of each raw material and the grinding powder of the adhesive or the mixed adhesive effect of each raw material and the forming agent can be different, so that the ground powder is mixed or stirred and kneaded together and then the optimal uniform mixing state is difficult to achieve, and the product performance and the quality obtained by production are unstable.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for preparing high-performance activated carbon by grinding, grading and kneading in a grading manner on the basis of a large amount of researches. The method adopts a process of grinding and mixing the raw materials with different cohesiveness and the caking agent in a grading proportion, is beneficial to improving the mixed bonding and interface bonding effects of the raw materials with low cohesiveness and the caking agent, and enables the mixed bonding effect of the carbon raw materials with different cohesiveness, the caking agent and the forming agent to reach the best, thereby reducing the using amount of the caking agent and realizing the low-cost and high-efficiency utilization of the raw materials; the method adopts a grading kneading process to improve the combination affinity and the binding power of the low-caking raw material and the high-caking raw material, so that the high-caking raw material and the low-caking raw material are mixed with the binding agent more uniformly, and the stability of the performance of the activated carbon product is improved.

According to the embodiment of the invention, a method for preparing high-performance activated carbon by classified grinding and classified kneading is provided.

A method for preparing high-performance activated carbon by classified milling and classified kneading comprises the following steps:

1) milling and first-stage kneading: mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material;

2) milling and secondary kneading: mixing and grinding the high-cohesiveness raw material and the binder, adding the auxiliary material, mixing with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material;

3) and (3) molding and granulating: extruding and molding the secondary kneaded material to obtain an active carbon precursor molding material;

4) and (3) drying: drying the active carbon precursor molding material to obtain a dried material;

5) and (3) heat treatment: and carrying out carbonization and activation reaction on the dried material to obtain the high-performance activated carbon.

In the present invention, the method further comprises:

6) cooling and screening: cooling and screening the high-performance activated carbon subjected to heat treatment to obtain large-particle high-performance activated carbon;

7) and (3) recycling: and (3) returning the small-particle activated carbon obtained after cooling and screening as an active raw material to the step 1) for reuse.

The size of the large-particle high-performance activated carbon in the step 6) is 4-12 mm.

Preferably, in step 1), the milling and the first-stage kneading process further include adding metal ore, specifically: mixing and grinding the active raw material, the low-caking material and the binder, adding the metal ore ground powder, mixing, and adding the auxiliary material to perform primary strong kneading to obtain a primary kneaded material.

Preferably, the metal ore is an iron-containing ore. Preferably one or more of iron manganese ore, iron copper ore, iron titanium ore and iron tungsten ore. Preferably, the ratio of the addition amount of the metal ore to the addition amount of all the carbon raw materials is a. Wherein: 0 < a.ltoreq.15%, preferably 0.1% < a.ltoreq.10%, more preferably 0.5% < a.ltoreq.8%.

All the carbon raw material addition amounts described herein refer to the total mass of all the carbon raw materials, that is, the total mass of the active raw material, the low-caking material and the high-caking material.

In the present invention, the binder is a non-asphalt-based binder (such as a novel binder prepared from sodium bentonite and pulverized coal) or an asphalt-based binder (such as coal asphalt and petroleum asphalt).

Preferably, the content of the binder mixed with the high-cohesiveness raw material in the step 2) is 0-80%, preferably 3-55%, and more preferably 5-30% of the content of the binder mixed with the low-cohesiveness raw material in the step 1).

In the invention, the auxiliary materials are a forming agent and water. Preferably, the forming agent is one or more of coal tar, carboxymethyl cellulose, polyvinyl alcohol and sesbania powder.

Preferably, the content of the forming agent in the auxiliary material added in the step 2) is 0-90%, preferably 5-70%, and more preferably 10-50% of the content of the forming agent in the auxiliary material added in the step 1).

In the invention, the mass percentage of each raw material in the secondary kneaded material obtained in the step 2) is as follows: 0-70 parts of active raw materials, 15-50 parts of low-cohesiveness raw materials, 15-50 parts of high-cohesiveness raw materials, 3-15 parts of binders, 7-20 parts of forming agents and 0-15 parts of metal ores.

In the invention, the active raw material in the step 1) is one or more of active carbon powder, active carbon production crushed material and waste powdered active carbon.

In the present invention, the low-caking additive has a caking index of 5 or less. Preferably, the low-caking raw material is one or two of coke powder and fly ash.

In the present invention, the caking index of the high-caking raw material in the step 2) is more than 5. Preferably, the high-caking raw material is one or more of coking coal, bituminous coal and anthracite.

Preferably, the milling is performed by milling each raw material until 90% or more passes through 200 mesh, preferably 95% or more passes through 200 mesh, and more preferably 97% or more passes through 200 mesh.

Preferably, the milling is performed by milling each raw material to a powder such that 70% or more passes through 325 mesh, preferably 75% or more passes through 325 mesh, and more preferably 80% or more passes through 325 mesh.

In the present invention, the heat treatment in step 5) is specifically: and adding the dried material into a carbonization furnace for carbonization to obtain a carbonized material. And then adding the carbonized material into an activation furnace, and introducing water vapor or carbon dioxide into the activation furnace to perform an activation reaction with the carbonized material to obtain the high-performance activated carbon.

Preferably, during the carbonization, the concentration of CO in the carbonization furnace is controlled. Preferably, the concentration of CO in the carbonization furnace is controlled to be b by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of a heat source of the carbonization furnace, wherein: 0 < b.ltoreq.45%, preferably 0.1% < b.ltoreq.40%, more preferably 0.5% < b.ltoreq.37%. The temperature range of carbonization is 300-900 ℃, preferably 400-850 ℃, and more preferably 500-800 ℃. The carbonization time is 15-180 min, preferably 20-120 min, and more preferably 30-90 min.

And in the activation reaction process, introducing mixed gas of water vapor and oxygen or introducing mixed gas of carbon dioxide and oxygen into the activation furnace. Preferably, the volume fraction of the oxygen amount in the mixed gas to the water vapor amount or the carbon dioxide amount is 0.1 to 5%, preferably 0.3 to 4%, and more preferably 0.5 to 3%. The temperature range of the activation reaction is 700-1100 ℃, preferably 800-1000 ℃, and more preferably 850-950 ℃. The time of the activation reaction is 20-240 min, preferably 30-180 min, and more preferably 40-120 min.

In the present invention, the heat treatment in step 5) is specifically: and adding the dried material into a carbonization-activation integrated furnace, and introducing water vapor or carbon dioxide to the furnace end of the carbonization-activation integrated furnace to perform carbonization-activation reaction with the dried material to obtain the high-performance activated carbon.

Preferably, the concentration of CO in the furnace is controlled during the carbonization-activation integrated heat treatment. Preferably, the concentration of CO in the carbonization-activation integrated furnace is controlled to be c by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of the heat source of the carbonization-activation integrated furnace, wherein: 0 < c.ltoreq.42%, preferably 0.1% < c.ltoreq.37%, more preferably 0.5% < c.ltoreq.35%.

Preferably, the temperature range of the heat treatment is 500-1100 ℃, preferably 600-1000 ℃, and more preferably 650-950 ℃; the time of the heat treatment is 15-240 min, preferably 20-180 min, and more preferably 30-120 min.

In the present invention, the primary intensive kneading and/or the secondary intensive kneading are/is intensively mixed by a batch mixer, a continuous mixer or an intensive mixer, and preferably an intensive mixer. Preferably, the kneading process is carried out with heat tracing, wherein the heat tracing temperature is 50-100 ℃, and preferably 70-90 ℃.

Preferably, the degree of mixing of the first-stage kneaded material and/or the second-stage kneaded material is 75% or more, preferably 80% or more, and more preferably 85% or more.

In the invention, the shape of the active carbon precursor molding material in the step 3) is one or more of spherical, cylindrical and rectangular. Preferably, the shape of the active carbon precursor molding material is cylindrical, and the size of the cylindrical active carbon precursor molding material is 4-12 mm, preferably 4.5-11 mm, and more preferably 5-10 mm.

Preferably, the activated carbon precursor molding material is dried in step 4) until the water content is less than 13%, preferably less than 10%, and more preferably less than 7%.

The raw materials for preparing the activated carbon generally comprise three major parts: raw material coal, binder and water, and other raw materials or additives having properties similar to those of raw coal may be added. Common raw material coal comprises coking coal, bituminous coal, anthracite and the like, the caking index of the common raw material coal is generally high (the caking index is more than 5), and the common raw material coal is classified as a high-caking raw material. Common raw material with the characteristics similar to that of raw coal comprises crushed materials produced by coke powder, carbon powder and activated carbon, waste powdered activated carbon and the like, wherein the coke powder, the fly ash and the like have low bonding indexes (the bonding index is less than or equal to 5) and are classified as low-bonding raw materials. The crushed materials and waste powdered activated carbon produced by carbon powder and activated carbon are classified as active raw materials, generally raw materials subjected to carbonization or activation treatment, and the bonding index and the bonding property of the active raw materials are also lower. The caking index is a key index for judging caking property and coking property of coal, and the caking power is the bonding force between molecules on the interface of a binding agent and an object to be bound. The preparation of the activated carbon usually adopts a coal blending method, and the high-temperature polycondensation and pyrolysis reaction of different coals are utilized to generate bridging bonding and a pore structure, so that the skeleton structure and the pore structure of the activated carbon are changed, and the strength performance, the adsorption performance and the like of the activated carbon are improved. The asphalt mainly plays a role of a binder in the preparation process of the activated carbon, and forms a skeleton structure inside the activated carbon after the activated carbon is carbonized at high temperature; the coal tar mainly plays a role of a binder and a lubricant in the preparation process of the activated carbon, has a lubricating effect in the forming and extruding process, prevents material blockage or material extrusion cracking, and simultaneously, the asphaltene in the coal tar can form a framework structure inside the activated carbon after high-temperature carbonization.

The method comprises the steps of mixing and grinding the active raw material by matching the low-caking raw material with the binder in a grading manner, matching the auxiliary material (the forming agent and the water) to perform primary strong kneading, matching the high-caking raw material with the binder to perform powder mixing and grinding, mixing the powder with the primary kneaded material obtained by the primary strong kneading, matching the auxiliary material (the forming agent and the water) to perform secondary strong kneading, and finally combining the procedures of forming granulation, drying, heat treatment and the like to prepare the high-performance desulfurization and denitrification active carbon, so that the active raw material, the low-caking raw material and the high-caking raw material can be utilized with low cost and high efficiency, the mixed bonding effect of the mixed material is improved while the usage amount of the binder is reduced, the stability of the performance of the active carbon is ensured, and the method has high application and popularization values. Through multiple tests, compared with the activated carbon prepared by the common method, the activated carbon prepared by the method has the advantages that the usage amount of the binder is reduced by more than 3%, and the usage amount of the forming agent is reduced by more than 5%; the wear resistance of the product is improved by 0.5-1.5%, the compressive strength is improved by more than 8%, and the uniformity is better.

The invention provides a method for preparing high-performance activated carbon by classified milling, classified kneading and related process technology principle is briefly described as follows:

1) different carbon materials have different caking properties (e.g., the caking property between coke powder and carbon powder is much lower than that between coke coal, bituminous coal and anthracite), so that the caking effect of each material mixed with a binder and pulverized coal or the caking effect of each material mixed with a forming agent is different, and therefore, more binders or forming agents are required to improve the forming property of the mixture or the interfacial bonding property of subsequent high-temperature reaction.

2) The carbon raw materials with different binding properties and the binding agent are milled and mixed together to be difficult to achieve the best mixing binding effect, and the better mixing binding effect is that the carbon raw materials with poorer binding properties and more or stronger binding agent are mixed and milled to improve the binding property and the mixing property of the carbon raw materials, namely, the low-binding-property raw materials are modified in viscosity; the carbon material with better binding performance can be mixed with less binder and ground into powder so as to improve or maintain the binding performance and mixing performance of the carbon material. Generally, the content of the binder in the high-adhesion raw material is 0 to 80% (preferably 3 to 55%, more preferably 5 to 30%) of the content of the binder in the low-adhesion raw material.

3) When the activated carbon is prepared, carbon raw materials (such as coke, bituminous coal, anthracite, coke powder, carbon powder and the like) and a binder (such as asphalt) are mixed and ground, then a forming agent (such as coal tar) is added to be mixed with water for extrusion forming, wherein the asphalt and the coal tar provide the functions of the binder and the forming agent, and the water can be used as a tackifier to play a role. The hardness of each raw material is different, and the raw materials are ground into fine powder with a certain particle size by using different grinding processes and equipment (for example, the raw materials are ground into powder with more than 95 percent of the powder passing through 200 meshes, or the raw materials are ground into powder with more than 70 percent of the powder passing through 325 meshes).

4) The low-cohesiveness raw material is matched with the adhesive, the milled powder is subjected to primary kneading with the forming agent, water and the like in advance, so that the affinity and the cohesive force of the combination of the low-cohesiveness raw material and the subsequent high-cohesiveness raw material can be improved, and the low-cohesiveness raw material is better in mixing and bonding effect, easier to mix uniformly and higher in mixing degree when the high-cohesiveness raw material is matched with the adhesive, the milled powder is subjected to secondary kneading. The reaction is more uniformly carried out after the heat treatment such as the subsequent carbonization and activation, and the quality stability of the product is ensured.

5) Because the degree of uniformly mixing the solid materials is limited, the fine solid materials of the coal powder, the carbon powder and the binder are required to be strongly mixed by a strong mixer to obtain a mixture with uniformly distributed coal powder-carbon powder-binder, and the coal powder, the carbon powder and the binder in the finally obtained activated carbon product are uniformly dispersed. The degree of mixing of the kneaded material is generally required to be 80%.

6) The heat tracing during kneading is helpful to improve the fluidity of the binder or the forming agent, thereby being helpful to improve the mixing and bonding effect of the raw materials, the binder and the forming agent.

7) And (3) molding and granulating: according to the application of the active carbon, the mixture is pressurized to be changed into an active carbon precursor molding material with a certain shape. The active carbon precursor molding material with a certain shape refers to the appearance of active carbon, and can be spherical, cylindrical, rectangular and the like, preferably cylindrical, for example, the size of the cylindrical active carbon precursor molding material is 5-10 mm.

8) And (3) drying: the active carbon precursor forming material has higher water content and is softer as a whole, the porosity and the strength of the active carbon can be influenced in the carbonization process, and the performance of the active carbon can not meet the requirements, so the active carbon precursor forming material is required to be dried until the water content is lower than 7 percent before carbonization.

9) And (3) heat treatment: the heat treatment process can adopt a step-by-step carbonization-followed activation treatment process or a carbonization-activation integrated treatment process.

CO assisted carbonization: the carbonization process is a reducing atmosphere, and under the atmosphere condition, metal oxides such as iron oxide, manganese oxide, copper oxide, titanium oxide, tungsten oxide and the like in the ore can be reduced. But because the carbonization temperature is medium-high temperature, the metal oxide is not reduced into simple substance, but only reduced into low-valence oxide, such as iron oxide changed into Fe₃O₄And the manganese oxide becomes MnO. Solid carbon in the activated carbon can be used as a reducing agent to reduce the metal oxide and generate CO at the same time; CO carried in the flue gas and oxygen in the flue gas react with solid carbon to generate partial CO; the obtained solid carbon and CO can participate in the process of reducing the metal oxide, and the reaction process is as follows:

MeO_n+C＝MeO_n-1+CO (1)；

2C+O₂＝2CO (2)；

MeO_n+CO＝MeO_n-1+CO₂ (3)；

however, the excessive participation of solid carbon in the reduction reaction can cause the quality loss of the activated carbon, and simultaneously can affect the strength of the activated carbon, so that the reactions (1) and (2) need to be inhibited in order to reduce the consumption of the activated carbon, and the reduction of CO is stronger than that of the solid carbon, so that the CO can preferentially and rapidly promote the reduction reaction of the metal oxide; in addition, CO is in a gaseous state and can enter the inside of the active carbon precursor forming material in the carbonization process, so that the porosity of the finally carbonized active carbon is increased. In order to promote the reaction (3), the CO concentration in the atmosphere (for example, the CO concentration is 0.5-37%) can be adjusted by regulating the supply amount of the coal gas at the source of the carbonization heat source, meanwhile, the air supply amount is controlled to prevent the coal gas from being combusted in a transition manner, limited oxygen led into the carbonization furnace preferentially reacts with volatile organic compounds in a combustion manner to reduce the loss of solid carbon, and finally, the purpose of rapidly reducing metal oxides by CO is achieved.

② low-oxygen activation: the carbonized material needs further pore-forming activation by water vapor, so that the carbon reacts with the water vapor. Meanwhile, a certain amount of oxygen can be introduced into the water vapor in the activation process (for example, the oxygen amount in the activation furnace accounts for 0.1-3% of the water vapor amount), and in the high-temperature activation process, after the oxygen is added into the water vapor atmosphere, the oxidation reaction of the oxygen and the solid carbon has remarkable opening and hole expansion effects on the activated carbon particles, the micropores, the specific surface area and the pore volume of the activated carbon particles are increased rapidly, so that an active site and favorable conditions are provided for the reaction of the activated carbon particles and sufficient water vapor, and the synergistic effect is promoted to occur. Meanwhile, the low-valence oxide formed in the carbonization process can be oxidized by water vapor and oxygen, so that high-valence metal oxide is obtained, and the reaction process is as follows:

2C+O₂＝2CO (4)；

C+H₂O＝CO+H₂ (5)；

MeO_n+O₂＝MeO_n+2 (6)；

MeO_n+H₂O＝MeO_n+1+H₂ (7)；

due to the carbonization reduction and the activation oxidation, the metal oxide in the activated carbon is subjected to the reduction and oxidation processes, the metal oxide is subjected to lattice remodeling, the internal porosity of the activated carbon is increased, and in the reduction process,MnO₂conversion to Mn₂O₃In the meantime, volume expansion of the mineral phase occurs, from Mn₂O₃Conversion to Mn₃O₄And MnO shrinkage in volume can occur; and in the oxidation process, from MnO to MnO₂And the volume expansion is generated, thereby being beneficial to obtaining the activated carbon with high porosity and specific surface area. Meanwhile, the powerful mixing equipment and the process ensure that the coal powder and the ore are fully and uniformly mixed when the raw materials are mixed, and the metal oxide in the finally obtained activated carbon product is uniformly dispersed.

10) The undersize powdered carbon has similar properties to activated carbon powder, belongs to an active raw material, and can be returned to be ground into powder to be used as a raw material for preparing the activated carbon.

As a preferred scheme, based on the phenomena and mechanisms that metal oxides in minerals can generate lattice remodeling in the activated carbon through deoxidation and oxidation in the high-temperature carbonization-activation process of the activated carbon, so that the porosity inside the activated carbon can be adjusted and catalytic active metals are uniformly loaded, and the like, the invention directly adds metal ores into the initial raw materials for preparing the activated carbon, and forms a uniform mixture of the metal ores, coal dust and a binder through mixing. Since the metal ore is often rich in various metal oxides, the metal oxides in the metal ore are reduced to lower-priced metal oxides in the carbonization process and then oxidized to higher-priced metal oxides in the activation process in the preparation process of the activated carbon. In the whole preparation process of the activated carbon, the metal oxide undergoes a reduction-oxidation process, the crystal structure of the metal oxide is reformed, and the metal oxide and C in the coal powder in the raw material are recrystallized to form a high-strength metal oxide-C substance, so that the uniform, stable and high-strength activated carbon doped with the metal oxide is finally obtained.

Compared with the prior art that metal soluble salt is added into the raw material of the activated carbon or the doped activated carbon is prepared by an impregnation method, in the prepared activated carbon doped with the metal oxide, the metal oxide and C are recrystallized, compared with the process of directly adding soluble salt, the chemical bond between the metal oxide and the C atom is firmer, the gap between the metal oxide and the C atom is smaller, and the acting force of the connecting bond is larger, so that the high-strength activated carbon doped with the metal oxide is formed. The active carbon prepared by the method is used for desulfurization and denitrification of the active carbon, and the active ions of the metal oxide are not easy to fall off due to the firm connection between the metal oxide and the C; because the active carbon needs to be circulated between the adsorption tower and the desorption tower for multiple times in the using process, after multiple tests, the metal oxide in the active carbon prepared by the invention can still be tightly combined in the active carbon, and still has the effects of high sulfur resistance and catalytic denitration.

In addition, the metal oxide in the metal ore is subjected to reduction and oxidation processes in sequence in the carbonization and activation processes. In each change process, the crystal structure of the metal oxide changes, and the change externally shows that the volume of the metal oxide changes. In the forming process of the activated carbon, the volume change of the metal oxide can promote the formation of pores of the activated carbon, and the pore opening and pore expansion effects on the activated carbon are obvious. Therefore, the crystal form change of the metal oxide promotes the pore formation of the activated carbon, and the specific surface area and the active catalytic site of the activated carbon are improved, so that the desulfurization and denitrification efficiency of the activated carbon is improved.

Compared with the prior art, the invention has the following beneficial technical effects:

1. the method of mixing the raw materials with different cohesiveness and the adhesive by grading proportion and grinding is beneficial to improving the mixed bonding and interface bonding effects of the raw materials with low cohesiveness and the adhesive, so that the mixed bonding effect of the carbon raw materials with different cohesiveness, the adhesive and the forming agent is optimal as much as possible, simultaneously, the method is also beneficial to improving the integral mixing degree of the materials in the subsequent mixing and kneading process, and then the qualified and stable activated carbon is prepared by granulation, drying, heat treatment, cooling and screening.

2. The classified kneading can improve the combination affinity and binding power of the low-caking raw material and the subsequent high-caking raw material, and the high-caking raw material, the low-caking raw material and the binding agent are mixed more uniformly, and the obtained product has more stable quality.

3. The combined process of graded milling and graded kneading can achieve the material mixing and bonding effect required by the subsequent process only by less adhesive and forming agent, improve the forming performance of the mixture or the interface bonding performance of the subsequent high-temperature reaction, and is beneficial to generating the co-carbonization effect.

4. According to the invention, the metal ore is directly added into the preparation raw material, the metal oxide in the metal ore undergoes the reduction-oxidation process, the crystal structure is reformed, and the crystal structure and the C in the coal powder are recrystallized simultaneously to form a high-strength metal oxide-C substance, so that the stable and high-strength active carbon doped with the metal oxide is finally obtained.

5. Compared with the activated carbon prepared by the common method, the activated carbon prepared by the process has the advantages that the usage amount of the binder and the forming agent is greatly reduced, the wear resistance and the compressive strength of the product are effectively improved, and the uniformity is better.

Drawings

FIG. 1 is a flow diagram of a prior art process for preparing activated carbon;

FIG. 2 is a flow chart of the process for preparing high-performance activated carbon by classified milling, classified kneading and kneading according to the invention;

FIG. 3 is a process flow diagram of the present invention for preparing high performance activated carbon by adding metal ore.

Detailed Description

According to the embodiment of the invention, a method for preparing high-performance activated carbon by classified grinding and classified kneading is provided.

A method for preparing high-performance activated carbon by classified milling and classified kneading comprises the following steps:

1) milling and first-stage kneading: mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material;

2) milling and secondary kneading: mixing and grinding the high-cohesiveness raw material and the binder, adding the auxiliary material, mixing with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material;

3) and (3) molding and granulating: extruding and molding the secondary kneaded material to obtain an active carbon precursor molding material;

4) and (3) drying: drying the active carbon precursor molding material to obtain a dried material;

5) and (3) heat treatment: and carrying out carbonization and activation reaction on the dried material to obtain the high-performance activated carbon.

In the present invention, the method further comprises:

6) cooling and screening: cooling and screening the high-performance activated carbon subjected to heat treatment to obtain large-particle high-performance activated carbon;

7) and (3) recycling: and (3) returning the small-particle activated carbon obtained after cooling and screening as an active raw material to the step 1) for reuse.

Preferably, in step 1), the milling and the first-stage kneading process further include adding metal ore, specifically: mixing and grinding the active raw material, the low-caking material and the binder, adding the metal ore ground powder, mixing, and adding the auxiliary material to perform primary strong kneading to obtain a primary kneaded material.

Preferably, the metal ore is an iron-containing ore. Preferably one or more of iron manganese ore, iron copper ore, iron titanium ore and iron tungsten ore. Preferably, the ratio of the addition amount of the metal ore to the addition amount of all the carbon materials (e.g., the active material, the low-caking material, and the high-caking material) is a. Wherein: 0 < a.ltoreq.15%, preferably 0.1% < a.ltoreq.10%, more preferably 0.5% < a.ltoreq.8%.

In the present invention, the binder is a non-asphalt-based binder (such as a novel binder prepared from sodium bentonite and pulverized coal) or an asphalt-based binder (such as coal asphalt and petroleum asphalt).

Preferably, the content of the binder mixed with the high-cohesiveness raw material in the step 2) is 0-80%, preferably 3-55%, and more preferably 5-30% of the content of the binder mixed with the low-cohesiveness raw material in the step 1).

In the invention, the auxiliary materials are a forming agent and water. Preferably, the forming agent is one or more of coal tar, carboxymethyl cellulose, polyvinyl alcohol and sesbania powder.

Preferably, the content of the forming agent in the auxiliary material added in the step 2) is 0-90%, preferably 5-70%, and more preferably 10-50% of the content of the forming agent in the auxiliary material added in the step 1).

In the invention, the mass percentage of each raw material in the secondary kneaded material obtained in the step 2) is as follows: 0-70 parts of active raw materials, 15-50 parts of low-cohesiveness raw materials, 15-50 parts of high-cohesiveness raw materials, 3-15 parts of binders, 7-20 parts of forming agents and 0-15 parts of metal ores.

In the invention, the active raw material in the step 1) is one or more of active carbon powder, active carbon production crushed material and waste powdered active carbon.

In the present invention, the low-caking additive has a caking index of 5 or less. Preferably, the low-caking raw material is one or two of coke powder and fly ash.

In the present invention, the caking index of the high-caking raw material in the step 2) is more than 5. Preferably, the high-caking raw material is one or more of coking coal, bituminous coal and anthracite.

Preferably, the milling is performed by milling each raw material until 90% or more passes through 200 mesh, preferably 95% or more passes through 200 mesh, and more preferably 97% or more passes through 200 mesh.

Preferably, the milling is performed by milling each raw material to a powder such that 70% or more passes through 325 mesh, preferably 75% or more passes through 325 mesh, and more preferably 80% or more passes through 325 mesh.

In the present invention, the heat treatment in step 5) is specifically: and adding the dried material into a carbonization furnace for carbonization to obtain a carbonized material. And then adding the carbonized material into an activation furnace, and introducing water vapor or carbon dioxide into the activation furnace to perform an activation reaction with the carbonized material to obtain the high-performance activated carbon.

Preferably, during the carbonization, the concentration of CO in the carbonization furnace is controlled. Preferably, the concentration of CO in the carbonization furnace is controlled to be b by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of a heat source of the carbonization furnace, wherein: 0 < b.ltoreq.45%, preferably 0.1% < b.ltoreq.40%, more preferably 0.5% < b.ltoreq.37%. The temperature range of carbonization is 300-900 ℃, preferably 400-850 ℃, and more preferably 500-800 ℃. The carbonization time is 15-180 min, preferably 20-120 min, and more preferably 30-90 min.

And in the activation reaction process, introducing mixed gas of water vapor and oxygen or introducing mixed gas of carbon dioxide and oxygen into the activation furnace. Preferably, the volume fraction of the oxygen amount in the mixed gas to the water vapor amount or the carbon dioxide amount is 0.1 to 5%, preferably 0.3 to 4%, and more preferably 0.5 to 3%. The temperature range of the activation reaction is 700-1100 ℃, preferably 800-1000 ℃, and more preferably 850-950 ℃. The time of the activation reaction is 20-240 min, preferably 30-180 min, and more preferably 40-120 min.

In the present invention, the heat treatment in step 5) is specifically: and adding the dried material into a carbonization-activation integrated furnace, and introducing water vapor or carbon dioxide to the furnace end of the carbonization-activation integrated furnace to perform carbonization-activation reaction with the dried material to obtain the high-performance activated carbon.

Preferably, the concentration of CO in the furnace is controlled during the carbonization-activation integrated heat treatment. Preferably, the concentration of CO in the carbonization-activation integrated furnace is controlled to be c by regulating the addition amount of fuel (such as coal powder or coal gas) at the source of the heat source of the carbonization-activation integrated furnace, wherein: 0 < c.ltoreq.42%, preferably 0.1% < c.ltoreq.37%, more preferably 0.5% < c.ltoreq.35%.

Preferably, the temperature range of the heat treatment is 500-1100 ℃, preferably 600-1000 ℃, and more preferably 650-950 ℃; the time of the heat treatment is 15-240 min, preferably 20-180 min, and more preferably 30-120 min.

In the present invention, the primary intensive kneading and/or the secondary intensive kneading are/is intensively mixed by a batch mixer, a continuous mixer or an intensive mixer, and preferably an intensive mixer. Preferably, the kneading process is carried out with heat tracing, wherein the heat tracing temperature is 50-100 ℃, and preferably 70-90 ℃.

Preferably, the degree of mixing of the first-stage kneaded material and/or the second-stage kneaded material is 75% or more, preferably 80% or more, and more preferably 85% or more.

In the invention, the shape of the active carbon precursor molding material in the step 3) is one or more of spherical, cylindrical and rectangular. Preferably, the shape of the active carbon precursor molding material is cylindrical, and the size of the cylindrical active carbon precursor molding material is 4-12 mm, preferably 4.5-11 mm, and more preferably 5-10 mm.

Preferably, the activated carbon precursor molding material is dried in step 4) until the water content is less than 13%, preferably less than 10%, and more preferably less than 7%.

Example 1

A method for preparing high-performance activated carbon by classified milling and classified kneading comprises the following steps:

1) milling and first-stage kneading: mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material;

2) milling and secondary kneading: mixing and grinding the high-cohesiveness raw material and the binder, adding the auxiliary material, mixing with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material;

3) and (3) molding and granulating: extruding and molding the secondary kneaded material to obtain an active carbon precursor molding material;

4) and (3) drying: drying the active carbon precursor molding material to obtain a dried material;

5) and (3) heat treatment: and carrying out carbonization and activation reaction on the dried material to obtain the high-performance activated carbon.

Example 2

Example 1 is repeated except that the method further comprises:

6) cooling and screening: cooling and screening the high-performance activated carbon subjected to heat treatment to obtain large-particle high-performance activated carbon;

7) and (3) recycling: and (3) returning the small-particle activated carbon obtained after cooling and screening as an active raw material to the step 1) for reuse.

Example 3

As shown in fig. 2, a method for preparing high-performance activated carbon by classified milling, classified kneading and kneading comprises the following steps:

1) milling and first-stage kneading: mixing and grinding the active raw material, the low-viscosity raw material and the binder, and then adding the auxiliary materials to carry out primary strong kneading to obtain a primary kneaded material.

The active raw material is crushed materials produced by active carbon, and the low-caking raw material is coke powder. The binder is coal tar pitch. The grinding is to grind the raw materials to more than 95 percent and pass through a 200-mesh sieve. The auxiliary materials are a forming agent and water, wherein the forming agent is coal tar. And the first-stage powerful kneading adopts a powerful mixer to perform powerful mixing, and the mixing degree is more than or equal to 80%. And carrying out heat tracing in the kneading process, wherein the heat tracing temperature is 80 ℃.

2) Milling and secondary kneading: and mixing the high-cohesiveness raw material and the binder, grinding the mixture into powder, adding the auxiliary material, mixing the powder with the primary kneaded material, and performing secondary strong kneading to obtain a secondary kneaded material. The secondary mixed and kneaded material comprises the following raw materials in percentage by mass: 40 parts of active raw materials, 30 parts of low-caking raw materials, 30 parts of high-caking raw materials, 8 parts of binders and 12 parts of forming agents.

The high-caking-property raw material is mixed coal of coking coal and bituminous coal. The binder is coal pitch, and the auxiliary materials are coal tar and water. The grinding is to grind the raw materials to more than 95 percent and pass through a 200-mesh sieve. And the secondary strong kneading adopts a strong mixing machine to carry out strong mixing, and the mixing degree is more than or equal to 80%. And carrying out heat tracing in the kneading process, wherein the heat tracing temperature is 80 ℃.

3) And (3) molding and granulating: and extruding and molding the secondary kneaded material to obtain the active carbon precursor molding material. The shape of the active carbon precursor molding material is cylindrical, and the size of the cylindrical active carbon precursor molding material is 8-10 mm.

4) And (3) drying: and drying the active carbon precursor molding material to obtain a dried material. And drying the active carbon precursor molding material until the water content is lower than 7%.

5) And (3) heat treatment: and adding the dried material into a carbonization furnace for carbonization to obtain a carbonized material. And then adding the carbonized material into an activation furnace, and introducing water vapor into the activation furnace to perform an activation reaction with the carbonized material to obtain the high-performance activated carbon.

Wherein, in the carbonization process, the concentration of CO in the carbonization furnace is controlled. The concentration of CO in the carbonization furnace is controlled to be 35 percent by regulating and controlling the addition amount of coal gas of the carbonization furnace. The carbonization temperature is raised to 700 ℃ at most, and the carbonization time is 80 min.

And introducing mixed gas of water vapor and oxygen into the activation furnace in the activation reaction process. The volume fraction of the oxygen amount in the mixed gas in the water vapor amount is 2%. The temperature of the activation reaction is raised to 900 ℃ at the most. The time of the activation reaction was 90 min.

6) Cooling and screening: and cooling and screening the high-performance activated carbon subjected to heat treatment to obtain large-particle high-performance activated carbon, wherein the particle size of the activated carbon is 8-10 mm.

7) And (3) recycling: and (3) returning the small-particle activated carbon obtained after cooling and screening as an active raw material to the step 1) for reuse.

The content of the binder which is mixed with the high-cohesiveness raw material in the step 2) is 25% of the content of the binder which is mixed with the low-cohesiveness raw material in the step 1). The content of the forming agent in the auxiliary material added in the step 2) is 40% of that in the auxiliary material added in the step 1).

Example 4

As shown in fig. 3, example 3 is repeated, except that in step 1), the milling and primary kneading process further includes adding metal ore, specifically: mixing and grinding the active raw material, the low-caking material and the binder, adding the metal ore ground powder, mixing, and adding the auxiliary material to perform primary strong kneading to obtain a primary kneaded material.

The secondary mixed and kneaded material comprises the following raw materials in percentage by mass: 40 parts of active raw materials, 30 parts of low-caking raw materials, 30 parts of high-caking raw materials, 8 parts of binders, 12 parts of forming agents and 4 parts of metal ores.

Example 5

Example 4 was repeated except that the binder was a novel binder prepared from sodium bentonite and coal dust. The content of the binder which is matched with the high-cohesiveness raw material in the step 2) is 20 percent of the content of the binder which is matched with the low-cohesiveness raw material in the step 1).

Example 6

Example 4 was repeated except that the milling was carried out so that more than 70% of each raw material passed through a 325 mesh.

Example 7

Example 4 was repeated except that the heat treatment described in step 5) was specifically: and adding the dried material into a carbonization-activation integrated furnace, and simultaneously introducing steam into the furnace end of the carbonization-activation integrated furnace to perform carbonization-activation reaction with the dried material to obtain the high-performance activated carbon. Wherein the heat treatment temperature is raised to 850 ℃ at most, and the heat treatment time is 120 min.

Comparative example 1

As shown in fig. 1, a preparation process of activated carbon specifically comprises the following steps: mixing and grinding a high-cohesiveness raw material, a low-cohesiveness raw material and a binder, then mixing the ground powder with a forming agent and water, and then sequentially forming, drying, carbonizing, activating, cooling and screening to obtain the finished product of the activated carbon. Wherein the relevant process conditions were the same as in example 3.

The relevant data of the activated carbon prepared in each example is recorded, and the activated carbon prepared in each example is used for flue gas desulfurization and denitration through engineering tests, and the test results are as follows:

compared with the activated carbon prepared by the common method, the activated carbon prepared by the method has the advantages that the usage amount of the binder and the forming agent is greatly reduced, the wear resistance and the compressive strength of the product are effectively improved, the product performance is more stable, the desulfurization and denitration efficiency of flue gas treated by the activated carbon is further improved, and the economic benefit and the social benefit are obvious.