Mineral-based composite active coke and preparation method thereof

Abstract

The invention relates to the technical field of active coke, in particular to mineral-based composite active coke and a preparation method thereof. The preparation method comprises the following steps: respectively crushing active coke and natural clay mineral, sieving, drying, mixing according to a certain ratio, adding a binder, fully kneading, uniformly mixing, carrying out compression molding, drying, carbonizing and activating to obtain the mineral-based composite active coke. The natural clay mineral is used as one of the raw materials, the natural clay mineral has a high specific surface area and a layered structure, and can be mixed with the active coke material to form a bridging effect in the active coke material and form a network structure, so that the overall strength of the material is improved, the layered structure can improve the pore connectivity of the active coke, and the pore connectivity of the active coke is improved. According to the present invention, the pore size is increased, such that the pores are opened so as to easily enter and diffuse the gas molecules, the pore volume is increased (-0.6 cm < 3 > / g), the high-medium-large pore volume ratio is increased (-80%), and the extremely high adsorption performance is provided for the small-molecule and large-molecule pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of activated coke, and particularly relates to a mineral-based composite activated coke and a preparation method thereof. Background Art

[0002] Activated carbon materials are mainly produced through processes such as forming, carbonization, and activation, and the application cost is relatively high. In addition, although activated carbon materials have characteristics such as a high specific surface area and a high iodine value, due to the collapse of the activated carbon structure during the preparation process, the proportion of micropores is relatively high and the pore volume is small, resulting in a small adsorption capacity for macromolecules or large-diameter pollutants and being prone to blockage. When treating sewage, since the components in sewage are usually complex, consisting of various mixtures of large and small molecules, it is difficult for activated carbon to selectively adsorb and remove various pollutants in sewage, which limits the application of activated carbon in fields such as advanced sewage purification. When purifying waste gas, a catalyst usually needs to be loaded in the pores. The high micropore content of activated carbon results in a reduction in the effective reaction active sites and a decrease in the catalytic desulfurization and denitrification efficiency.

[0003] Activated coke has advantages such as low cost and a relatively low proportion of micropores, and is an important material to replace activated carbon materials. It has shown good application prospects in fields such as advanced purification of wastewater and waste gas, and has achieved industrial application. In the prior art, activated coke is mainly prepared from raw materials such as pulverized coal, semi-coke, and binder, and usually needs to go through processes such as high-pressure forming, carbonization, and activation. However, the pore structure of activated coke is relatively single and the adsorption effect is average. In the prior art, the pore structure is often enriched by increasing the activation temperature. However, too high an activation temperature will lead to a decrease in the strength of activated coke, easy pulverization, and greatly reduce its adsorption performance. Summary of the Invention

[0004] The purpose of the present invention is to propose a mineral-based composite activated coke and a preparation method thereof in view of the above-mentioned deficiencies of the prior art.

[0005] A preparation method of a mineral-based composite activated coke of the present invention is to crush, sieve, and dry the activated coke raw material and natural clay minerals respectively, then mix them in proportion, add a binder and knead and mix evenly, press into a shape, and then dry, carbonize, and activate to obtain the mineral-based composite activated coke.

[0006] Further, the natural clay mineral is one or more of zeolite, bentonite, attapulgite, montmorillonite, vermiculite, and sepiolite clay.

[0007] Further, the particle size distribution of the crushed and sieved natural clay mineral is in the range of 100-400 mesh.

[0008] Further, the mass ratio of the natural clay mineral to the activated coke raw material is 5-20:80-95.

[0009] Further, the binder is one or more of coal tar, sodium humate, starch, sodium silicate, coal pitch, sodium carboxymethyl cellulose, sodium alginate, and polyacrylamide.

[0010] Further, the mass ratio of the binder to the sum of the masses of the natural clay mineral and the activated coke raw material is 1-20:100.

[0011] Further, the activated coke raw material includes one or more of lignite, bituminous coal, anthracite, and semi-coke; the particle size distribution of the crushed and sieved activated coke is 80-200 mesh; the activated coke raw material is crushed and sieved through 60-80 mesh and 150-160 mesh sieves and mixed in a mass ratio of 7-10:1.

[0012] Further, the pressure for pressing and forming is 1-20 MPa, and the pressure holding time is 1-10 min; the carbonization temperature is 300-500 °C, the carbonization time is 30-240 min, and the carbonization protective atmosphere is one or more of nitrogen, ammonia, argon, and helium.

[0013] Further, the activation temperature is 600-1000 °C, the activation time is 30-240 min, and the activation atmosphere is one or more of carbon dioxide, water vapor, and ammonia; the flow rate of the activator is 1-100 mL / min.

[0014] A mineral-based composite activated coke prepared by the above preparation method.

[0015] Beneficial effects:

[0016] (1) In the present invention, natural clay minerals are used as one of the raw materials. Natural clay minerals have a high specific surface area and a layered structure. They can be mixed with the activated coke material to form a bridging effect in the activated coke material and form a network structure, thereby increasing the overall strength of the material and not being prone to pulverization; it does not float in water and still maintains a high strength when encountering water, and has good application in sewage treatment plants.

[0017] (2) For the activated coke material provided by the present invention, adding natural clay minerals will slightly reduce the specific surface area of the activated coke, but its layered structure can improve the pore connectivity of the activated coke, making the pores more open, facilitating the entry and diffusion of gas molecules, increasing the pore volume (~0.6 cm 3 / g) and the proportion of medium-large pore volume (~80%), showing extremely high adsorption performance for both small and large molecule pollutants, and can simultaneously achieve the co-adsorption of small and large molecules.

[0018] (3) In the preparation method of the present invention, under the same process conditions, after adding natural minerals, the strength of the prepared activated coke material is improved, and the adsorption performance for both small and large molecules can be improved to varying degrees, and the co-adsorption of small and large molecules can be achieved synchronously.

[0019] (4) The activated coke material provided by the present invention can be widely applied to aspects such as decolorization of urban sewage treatment plants, removal of pollutants from biochemical wastewater, removal of heavy metal pollution, flue gas desulfurization and denitrification, gas adsorption and deodorization, and adsorption and degradation of VOCs. Description of the Drawings

[0020] Figure 1 Adsorption isotherm of the activated coke material prepared in Example 1;

[0021] Figure 2 Adsorption isotherm of the activated coke material prepared in Comparative Example 1;

[0022] Figure 3 Pore size distribution diagram of the activated coke material prepared in Example 1;

[0023] Figure 4 Pore size distribution diagram of the activated coke material prepared in Comparative Example 1. Detailed Embodiments

[0024] The following are specific embodiments of the present invention in combination with the drawings, and the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0025] Example 1

[0026] The semi-coke was crushed to different finenesses, passed through 80-mesh and 150-mesh sieves respectively, and mixed and sized according to a mass ratio of 9:1 to obtain a first solid mixture. The zeolite powder was compounded with the first solid mixture according to a mass ratio of 5:95 to obtain a second solid mixture. Coal tar pitch (mass ratio to the second solid mixture is 15:100) and coal tar (mass ratio to the second solid mixture is 15:100) were added to the second solid mixture, and kneaded and mixed thoroughly to obtain a third solid mixture. The third solid mixture was pressed into columnar shaped strips under a pressure of 10 MPa, namely a fourth solid mixture. The fourth solid mixture was placed for high-temperature carbonization treatment, the carbonization temperature was 400 °C, and the carbonization time was 60 min to obtain a fifth solid mixture. The fifth solid mixture was subjected to high-temperature activation treatment, the activation temperature was 900 °C, the activation time was 90 min, the activation atmosphere was water vapor, and the water vapor flow rate was 1 g / min to obtain a sixth solid mixture, which is the activated coke product.

[0027] Example 2

[0028] The semi-coke is crushed to different finenesses, passed through 80-mesh and 150-mesh sieves respectively, and mixed and graded according to a mass ratio of 9:1 to obtain the first solid mixture. The montmorillonite powder is compounded with the first solid mixture according to a mass ratio of 5:95 to obtain the second solid mixture. Coal tar pitch (with a mass ratio of 15:100 to the second solid mixture) and coal tar (with a mass ratio of 15:100 to the second solid mixture) are added to the second solid mixture, and kneaded and mixed thoroughly to obtain the third solid mixture. The third solid mixture is pressed into columnar formed strips at a pressure of 10 MPa, i.e., the fourth solid mixture. The fourth solid mixture is subjected to high-temperature carbonization treatment at a carbonization temperature of 400 °C and a carbonization time of 60 min to obtain the fifth solid mixture. The fifth solid mixture is subjected to high-temperature activation treatment at an activation temperature of 900 °C, an activation time of 90 min, an activation atmosphere of steam, and a steam flow rate of 1 g / min to obtain the sixth solid mixture, which is the activated coke product.

[0029] Example 3

[0030] The semi-coke is crushed to different finenesses, passed through 80-mesh and 150-mesh sieves respectively, and mixed and graded according to a mass ratio of 9:1 to obtain the first solid mixture. The bentonite powder is compounded with the first solid mixture according to a mass ratio of 5:95 to obtain the second solid mixture. Coal tar pitch (with a mass ratio of 15:100 to the second solid mixture) and coal tar (with a mass ratio of 15:100 to the second solid mixture) are added to the second solid mixture, and kneaded and mixed thoroughly to obtain the third solid mixture. The third solid mixture is pressed into columnar formed strips at a pressure of 10 MPa, i.e., the fourth solid mixture. The fourth solid mixture is subjected to high-temperature carbonization treatment at a carbonization temperature of 400 °C and a carbonization time of 60 min to obtain the fifth solid mixture. The fifth solid mixture is subjected to high-temperature activation treatment at an activation temperature of 900 °C, an activation time of 90 min, an activation atmosphere of steam, and a steam flow rate of 1 g / min to obtain the sixth solid mixture, which is the activated coke product.

[0031] Comparative Example 1

[0032] The process is the same as that of Example 1, except that no minerals are added. The specific steps are as follows:

[0033] The semi-coke is crushed to different finenesses, passed through 80-mesh and 150-mesh sieves respectively, and mixed and graded according to a mass ratio of 9:1 to obtain a first solid mixture. Coal tar pitch (mass ratio to the first solid mixture is 15:100) and coal tar (mass ratio to the first solid mixture is 15:100) are added to the first solid mixture, and kneaded and mixed thoroughly to obtain a second solid mixture. The second solid mixture is pressed into columnar shaped strips under a pressure of 10 MPa, namely the fourth solid mixture. The third solid mixture is subjected to high-temperature carbonization treatment at a carbonization temperature of 400 °C and a carbonization time of 60 min to obtain a fourth solid mixture. The fourth solid mixture is subjected to high-temperature activation treatment at an activation temperature of 900 °C, an activation time of 90 min, and an activation atmosphere of water vapor with a water vapor flow rate of 1 g / min to obtain a fifth solid mixture, which is the activated coke product.

[0034] Table 1: Specific surface area and pore structure characteristics of the activated coke materials prepared in the examples and comparative examples of the present invention.

[0035] Table 1

[0036]

[0037] Table 2: Iodine adsorption value and methylene blue value of the activated coke materials prepared in the examples and comparative examples of the present invention.

[0038] Table 2

[0039]

[0040]

[0041] Table 3: Compressive strength and yield of the activated coke materials prepared in Example 1 and Comparative Example 1 of the present invention.

[0042] Table 3

[0043] Sample Compressive strength (N) Yield (%) Example 1 119.66 30.71 Comparative Example 1 102.35 28.72

[0044] Table 4: Iodine adsorption value, methylene blue value and yield of the activated coke materials prepared by changing the addition amount of zeolite in Example 1.

[0045] Table 4

[0046] As Figure 1 and Figure 2 shown, the nitrogen adsorption-desorption isotherms of the activated coke materials prepared in Example 1 and Comparative Example 1 of the present invention both belong to type II adsorption isotherms, and the hysteresis loop is of H3 type, indicating that the pore structure is very irregular. The pore type structures reflected by H3 type include flat slit structures, cracks and wedge structures, etc., and belong to typical flaky particle materials (such as clay), or fissured pore materials.

[0047] Figure 3 and Figure 4 Figures 0000118 and 0000119 are the pore size distribution diagrams of the activated coke materials in Example 1 and Comparative Example 1. It can be seen from the figures that both are mixtures of micropores and mesopores. However, the pore size distribution of the activated coke material in Example 1 is more extensive, covering the range from micropores to macropores, while that in Comparative Example 1 is mainly concentrated in the micropore region. At the same time, at the corresponding pore sizes, the samples in Example 1 have a higher pore volume. Table 1 shows the specific surface area and pore structure characteristics of the activated coke materials prepared in Example 1 and Comparative Example 1, which Figure 3 and Figure 4 are consistent with the results.

[0048] Table 2 shows the iodine value and methylene blue value results of the examples. The iodine value reflects the adsorption capacity of the activated coke for small molecules and is usually used to evaluate the microporous structure of the activated coke. A high iodine value indicates that the activated coke has more micropores, and these micropores have strong adsorption performance for small molecule organic substances. The methylene blue value represents the adsorption performance of the activated coke for macromolecules. A high methylene blue adsorption value means that the activated coke has a strong adsorption capacity for larger molecule organic substances, which is usually related to the development degree of mesopores and macropores. The results of the compressive strength and yield of the examples are shown in Table 3. The results show that adding natural zeolite can improve the strength of the activated coke and increase the yield at the same time.

[0049] Table 4 shows the iodine adsorption value, methylene blue value and yield of the activated coke materials prepared by changing the addition amount of zeolite in Example 1. It can be seen from Table 4 that when the addition amount of zeolite is 5%, the adsorption performance of both small and large molecules is the best.

[0050] Where not covered above, the prior art applies.

[0051] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways for substitution, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing mineral-based composite activated coke, characterized in that: The activated coke raw material and natural clay mineral are crushed, sieved and dried respectively, then mixed in proportion, and then a binder is added to fully knead and mix, and then pressed into shape, dried, carbonized and activated to obtain mineral-based composite activated coke.

2. The preparation method according to claim 1, characterized in that: The natural clay mineral is one or more of zeolite, bentonite, attapulgite, montmorillonite, vermiculite and sepiolite.

3. The preparation method according to claim 1, characterized in that: The natural clay mineral is crushed and sieved to have a particle size distribution of 100 to 400 meshes.

4. The preparation method according to claim 1, characterized in that: The mass ratio of natural clay mineral to activated coke raw material is 5-20:80-95.

5. The preparation method according to claim 1, characterized in that: The binder is one or more of coal tar, sodium humate, starch, sodium silicate, coal tar, sodium hydroxymethyl cellulose, sodium alginate and polyacrylamide.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the binder to the sum of the mass of the natural clay mineral and the activated coke raw material is 1 to 20:

100.

7. The preparation method according to claim 1, characterized in that: The activated coke raw material includes one or more of lignite, bituminous coal, anthracite, and semi-coke; the activated coke raw material is crushed and sieved to have a particle size distribution of 80 to 200 meshes; the activated coke raw material is crushed through 60-80 mesh and 150-160 mesh sieves and mixed at a mass ratio of 7-10:

1.

8. The preparation method according to claim 1, characterized in that: The pressing pressure is 1-20 MPa, the holding time is 1-10 min; the carbonization temperature is 300-500° C., the carbonization time is 30-240 min, and the carbonization protective atmosphere is one or more of nitrogen, ammonia, argon and helium.

9. The preparation method according to claim 1, characterized in that: The activation temperature is 600-1000° C., the activation time is 30-240 min, the activation atmosphere is one or more of carbon dioxide, water vapor, and ammonia; and the flow rate of the activating agent is 1-100 mL / min.

10. Mineral-based composite activated coke prepared by the preparation method according to any one of claims 1 to 9.

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