CN115261048A

CN115261048A - Method for coking by using lignin in papermaking black liquor and blending coal

Info

Publication number: CN115261048A
Application number: CN202210986974.6A
Authority: CN
Inventors: 吴鹏飞; 杨磊; 赵璐璐; 张颖昆; 刘兆龙; 赵士宁; 程章豪; 温帅云; 张筱; 主晓磊
Original assignee: Hebei College of Industry and Technology
Current assignee: Hebei College of Industry and Technology
Priority date: 2022-08-17
Filing date: 2022-08-17
Publication date: 2022-11-01
Anticipated expiration: 2042-08-17
Also published as: CN115261048B

Abstract

The invention relates to a method for coking by using lignin in papermaking black liquor and blending coal, which comprises the following steps: s1, extracting lignin from papermaking black liquor, drying and grinding the lignin into lignin particles; s2, blending gas coal, 1/3 coking coal, gas fat coal, no. 1 coking coal, no. 2 coking coal, no. 3 coking coal, fat coal, lean coal, poor lean coal and lignin particles prepared in the S1 according to a proportion to obtain blended coal, and crushing the blended coal to be less than 3 mm; s3, adjusting the total moisture of the blended coal to 10 +/-2 percent and the bulk density of the blended coal to 0.9-1.1 multiplied by 10 ³ kg/m ³ Then the coke is sent into a coke oven for coking, and the coking time is 15 to 24 hours; and pushing out the red coke after the coke is mature, quenching the coke by using water, and airing to obtain the metallurgical coke. The lignin extracted from the papermaking black liquor replaces part of gas coal (replaces part of caking high-quality coal in coal blending), and the lignin is limited to a proper addition amount, so that the problems of shortage of strong caking high-quality coal and insufficient ratio of strong caking coal in the conventional coking coal blending process are solvedThe coke strength is reduced, and the lignin in the papermaking black liquor is wasted.

Description

Method for coking by blending coal with lignin in papermaking black liquor

Technical Field

The invention belongs to the technical field of coal blending coking, and particularly relates to a method for coal blending coking by using lignin in papermaking black liquor.

Background

Coking is a process of decomposing coal by high-temperature heating under the condition of air isolation to obtain coke, coal gas, coal tar and the like. In coking coal, high-quality coal with strong caking property is less and less, and in the process of coking and coal blending, the caking property of coke is insufficient and the strength is reduced due to the problem of the blending ratio of the coal with strong caking property. Meanwhile, the papermaking black liquor contains a large amount of lignin, and more than 95% of the lignin is counted as the waste of papermaking pulping, and is directly discharged into rivers or is burnt after being concentrated along with the waste water, so that the lignin is rarely utilized, and the serious pollution is brought to a water body.

In conclusion, in the field of coal blending and coking, the problems of high-quality coal shortage with strong caking property and coke strength reduction caused by insufficient blending ratio of the coal with strong caking property exist; in the paper industry, a large amount of lignin in black liquor generated in paper making is discharged to the environment as waste, so that lignin resource waste and environmental pollution are caused.

Disclosure of Invention

Technical problem to be solved

In view of the defects and shortcomings of the prior art, the invention provides a method for coking by blending coal with lignin in papermaking black liquor, and the scheme replaces part of gas coal (replacing part of caking high-quality coal in blended coal) with lignin extracted from the papermaking black liquor, thereby solving the technical problems that the coke strength is reduced and the lignin in the papermaking black liquor is wasted due to the shortage of strong caking high-quality coal and the insufficient blending ratio of the strong caking coal in the conventional coking and blending coal process.

(II) technical scheme

In order to achieve the aim, the invention provides a method for coking by using lignin in papermaking black liquor and blending coal, which comprises the following steps:

s1, extracting lignin from papermaking black liquor, drying and grinding the lignin into lignin particles;

s2, blending gas coal, 1/3 coking coal, gas fat coal, no. 1 coking coal, no. 2 coking coal, no. 3 coking coal, fat coal, lean coal, poor lean coal and lignin particles prepared in the S1 according to a proportion to obtain blended coal, and crushing the blended coal to be less than 3 mm;

s3, adjusting the total moisture of the blended coal to 10 +/-2 percent and the bulk density of the blended coal to 0.9-1.1 multiplied by 10 ³ kg/m ³ Then the coke is sent into a coke oven for coking, and the coking time is 15 to 24 hours; and pushing out the red coke after the coke is mature, quenching the coke by using water, and airing.

According to a preferred embodiment of the invention, in S1, the method for extracting lignin from the papermaking black liquor comprises the following steps: mixing paper-making black liquor and absolute ethyl alcohol according to the volume ratio of 1:1-1.5, mixing, performing primary water bath at 45-75 ℃ for 1-3h, standing for layering, and taking supernatant; evaporating the supernatant to remove ethanol, slowly adding concentrated sulfuric acid or concentrated nitric acid to adjust the pH =2-3, heating the solution in a water bath at 45-75 ℃ for 6-7h until no more precipitate is generated in the solution, centrifuging the solution and the precipitate, drying and centrifuging the obtained solid to obtain lignin;

or mixing the papermaking black liquor and sodium hydroxide according to the mass ratio of 8.5-12, heating and boiling for 30-40min, filtering the boiled papermaking black liquor, separating to obtain filtrate, adjusting the pH of the filtrate to 4.0-4.5 by using dilute hydrochloric acid, standing and precipitating for 1-3h, filtering or centrifuging, and drying to obtain the lignin.

Wherein, the extraction of lignin from the papermaking black liquor is a mature process, and the technical personnel in the field can extract lignin by any feasible method.

According to a preferred embodiment of the present invention, in S2, the composition of the blending coal is: 9 to 11 percent of gas coal, 16 to 20 percent of 1/3 coking coal, 5.5 to 6.5 percent of gas fat coal, 5.5 to 6.5 percent of coking coal No. 1, 12.5 to 15.5 percent of coking coal No. 2, 13.5 to 16.5 percent of coking coal No. 3, 8 to 10 percent of fat coal, 9 to 11 percent of lean coal, 7.2 to 8.8 percent of lean coal and 3.5 to 5 percent of lignin particles; the total amount of the above components is 100%.

According to the preferred embodiment of the invention, in S2, the coal quality index of the blended coal satisfies the following conditions: the dry base ash content Ad is 9.90-10.5, the dry ash-free base volatile component Vdaf is 26-30, the dry base total sulfur St is 0.65-0.80, the caking index G is 66.0-70, and the maximum thickness Y of the colloidal layer is 12.5-13.8.

According to a preferred embodiment of the present invention, in S2, the composition of the blending coal is: 10% of gas coal, 18% of 1/3 coking coal, 6% of gas fat coal, 6% of coking coal No. 1, 14% of coking coal No. 2, 15% of coking coal No. 3, 9% of fat coal, 10% of lean coal, 8% of lean coal and 4% of lignin particles; the total amount of the above components is 100%.

According to the preferred embodiment of the present invention, in S2, the coal quality index of the blended coal satisfies: dry base ash Ad was 9.97, dry ash free volatiles Vdaf was 29.28, dry base total sulfur St was 0.71, sticking index G was 69.24, and the maximum colloidal layer thickness Y was 13.20.

According to the preferred embodiment of the present invention, in S3, the total moisture content of the blended coal is adjusted to 10%, and the bulk density is adjusted to 1X 10 ³ kg/m ³ Coking for 18h in a coke oven.

In the present application, the percentages in the composition of the blended coal are by mass.

(III) advantageous effects

The lignin extracted from the papermaking black liquor in a certain proportion is added in the coal blending coking process, and the lignin can be used as an adhesive to replace high-quality coal which plays a binding role in coal blending, so that the use amount of the high-quality coal is reduced. Experiments show that a certain proportion of lignin is added into the coal blending, and M in coke strength values obtained by coking ₄₀ And M ₂₅ Are all obviously improved and M ₁₀ Slightly reduced, the mechanical strength of the coke can be obviously improved, the influence on the hot state strength CSR of the coke is not obvious, and the hot state strength CSR can still be kept at 65 or more, thus reaching the standard of the first-grade metallurgical coke. It can also be seen from the SEM image of the coke that the addition of a certain amount of lignin in the coal blending coking is beneficial to the bonding of coal materials, the pore wall of the formed coke is thicker, the pore size is uniform and very tends to be consistent, the micro-cracks are less, and the consistency with the strength test value is shown.

The lignin is extracted from the paper-making waste liquid, and replaces caking high-quality coal in coal blending for coking, so that the problems of shortage of strong caking high-quality coal and reduction of coke strength caused by insufficient proportion of the strong caking coal in the coking and coal blending process can be solved, and the problem of pollution of the paper-making waste liquid can be solved to a certain extent.

Drawings

FIG. 1 is a comparison of SEM images of cokes produced in example 1 of the present invention and comparative example 1.

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present embodiments of the invention, which are illustrated in the accompanying drawings.

Lignin is the second largest polymeric material in nature in quantities, which is regenerated at a rate of 600 trillion tons each year (from tree growth), and is a potentially very renewable resource. The lignin is a complex aromatic polymer, is a macromolecular organic compound with a three-dimensional network structure formed by connecting phenylpropane units through ether bonds and carbon-carbon bonds, has a large number of active groups on the macromolecular structure, such as carbonyl, carboxyl, hydroxyl, methoxyl and the like, can well form chemical connection with groups on the surface of biomass, and is very suitable for serving as a coal binder. In addition, it has a high calorific value and can be used as an energy source. The phenolic hydroxyl group is an important functional group structure in the macromolecule of the lignin, and the existence of the phenolic hydroxyl group enables the lignin to easily form quinone intermediates in the pyrolysis process so as to promote the generation of coke. However, as the main component in the black liquor, more than 95% of lignin as paper making waste is directly discharged into rivers or is burnt after being concentrated along with the waste water, and is not effectively utilized. Therefore, the invention adds the lignin extracted from the paper-making black liquor into the coal blending coking process, and substitutes part of high-quality caking coal, especially gas coal, with the lignin, thereby achieving the purposes of improving the mechanical strength of coke, solving the problems of coke strength reduction and paper-making waste liquor pollution caused by shortage of high-caking coal and insufficient proportioning of high-caking coal, and realizing full utilization of lignin resources.

The technical effects of the present invention will be described below with reference to specific examples and comparative examples.

Example 1

The embodiment is a coal blending coking method with added lignin, wherein the lignin is extracted from black liquor of papermaking pulping, and the extraction method comprises the following steps: mixing the papermaking black liquor and sodium hydroxide according to the mass ratio of 10. The blending ratio of the coal in the embodiment is as follows:

blending the single coal and lignin according to the table to obtain blended coal, and crushing the blended coal to be less than 3 mm. Regulating the total water content of blended coal to 10% and the bulk density to 1.0X 10 ³ kg/m ³ Then the mixture is sent into a 40kg experimental coke oven for coking, and the coking time is 18h. After the coke is mature, the red coke is pushed out and quenched by water, and the strength index of the coke is measured after the coke is dried.

Comparative example 1

In the example, the components and the proportion of the blended coal are changed on the basis of the example 1. In the comparative example, 4% of lignin is removed from the example 1, and 10% of the gas coal in the example 1 is adjusted to 14%.

The strength indexes of the cokes prepared in example 1 and comparative example 1 were measured, and the results were compared as follows:

coke samples	M ₄₀ ，％	M ₂₅ ，％	M ₁₀ ，％	CRI，％	CSR，％
						Comparative example 1	82	92	6.5	24	67
Example 1	88	97	6.2	25	66

The comparison result shows that the coke M prepared by adding a certain proportion of lignin to replace a part of gas coal ₄₀ And M ₂₅ All increased, while M10 decreased slightly. The invention shows that the mechanical strength of the coke can be improved by adding a certain amount of lignin in the coal blending processThe influence on the hot-state strength CSR of the coke is not obvious and is still more than 65 percent, and the standard of the first-grade metallurgical coke is achieved (the general standard of the first-grade metallurgical coke requires that the CSR is more than or equal to 55 percent, the CRI is less than or equal to 35 percent, the individual standard requires that the CSR is more than or equal to 60 percent and the CRI is less than or equal to 30 percent).

Referring to FIG. 1, SEM pictures of cokes prepared in example 1 and comparative example 1 are shown. The coke prepared in example 1 is shown on the left side of the figure, and the coke prepared in comparative example 1 is shown on the right side of the figure. After a certain amount of lignin is added on the left side, the pore walls of the formed coke are thicker, the pore sizes are uniform and tend to be very consistent, and microcracks are less, which shows consistency with a strength test value.

Example 2

This example is the same as example 1 except that the blending ratio was adjusted as follows:

after the coke is mature, the red coke is pushed out and quenched by water, and the strength index of the coke is measured after the coke is dried.

Example 3

after the coke is mature, the red coke is pushed out and quenched by water, and the strength index of the coke is measured after the coke is dried in the air.

Coke samples	M ₄₀ ，％	M ₂₅ ，％	M ₁₀ ，％	CRI，％	CSR，％
						Example 2	87	96	6.3	25	68
Example 3	89	99	6.0	27	67

As can be seen from the above examples, the cokes prepared in examples 2-3 can meet the standard requirements of primary metallurgical coke that the CSR is more than or equal to 55 percent and the CRI is less than or equal to 35 percent.

Comparative example 2

In the example, the components and the proportion of the blended coal are changed on the basis of the example 1. The comparison example is mainly to increase 4% lignin to 8% on the basis of example 1, and adjust 10% gas coal to 6% in example 1. The strength index of the coke produced in comparative example 2 was measured, and the results were as follows:

coke samples	M ₄₀ ，％	M ₂₅ ，％	M ₁₀ ，％	CRI，％	CSR，％
						Comparative example 2	90	100	6.5	32.4	57.6

From the above results, it is understood that when the amount of lignin added is too high, the M content of coke can be increased ₄₀ And M ₂₅ However, in this case, the coke thermal state strength CSR is greatly adversely affected, and a coke having excellent comprehensive metallurgical properties cannot be obtained.

Comparative example 3

In this example, on the basis of example 1, the coking conditions were changed as follows: regulating the total water content of blended coal to 6% and the bulk density to 0.7X 10 ³ kg/m ³ Then the mixture is sent into a 40kg experimental coke oven for coking, and the coking time is 18h. After the coke was matured, the red coke was pushed out and quenched with water, air dried, and the strength index of the coke prepared in comparative example 3 was measured, and the results were compared as follows:

coke samples	M ₄₀ ，％	M ₂₅ ，％	M ₁₀ ，％	CRI，％	CSR，％
						Comparative example 3	82	90	6.3	30	60
Example 1	88	97	6.2	26	66

It can be seen that M, which is the total moisture content and bulk density of the coke product in the blended coal during coking ₄₀ 、M ₂₅ And CSR, etc. have an effect.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for coking by using lignin mixed with coal in papermaking black liquor is characterized by comprising the following steps:

s2, blending the gas coal, 1/3 coking coal, gas fat coal, coking coal No. 1, coking coal No. 2, coking coal No. 3, fat coal, lean coal, poor lean coal and lignin particles prepared in the S1 according to a proportion to obtain blended coal, and crushing the blended coal to be less than 3 mm;

s3, adjusting the total moisture of the blended coal to 10 +/-2 percent and the bulk density of 0.9-1.1 multiplied by 10 ³ kg/m ³ Then the mixture is sent into a coke oven for coking, wherein the coking time is 15 to 24 hours; and pushing out the red coke after the coke is mature, quenching the red coke by using water, and airing the red coke.

2. The method according to claim 1, wherein in S1, the method for extracting lignin from the papermaking black liquor comprises the following steps: mixing papermaking black liquor and absolute ethyl alcohol according to a volume ratio of 1:1-1.5, mixing, performing primary water bath at 45-75 ℃ for 1-3h, standing for layering, and taking supernatant; evaporating the supernatant to remove ethanol, slowly adding concentrated sulfuric acid or concentrated nitric acid to adjust the pH =2-3, heating the solution in a water bath at 45-75 ℃ for 6-7h until no more precipitate is generated in the solution, centrifuging the solution and the precipitate, drying and centrifuging the obtained solid to obtain lignin;

3. The method according to claim 1, wherein in S2, the composition of the blended coal is: 9 to 11 percent of gas coal, 16 to 20 percent of 1/3 coking coal, 5.5 to 6.5 percent of gas fat coal, 5.5 to 6.5 percent of coking coal No. 1, 12.5 to 15.5 percent of coking coal No. 2, 13.5 to 16.5 percent of coking coal No. 3, 8 to 10 percent of fat coal, 9 to 11 percent of lean coal, 7.2 to 8.8 percent of lean coal and 3.5 to 5 percent of lignin particles; the total amount of the above components is 100%.

4. The method according to claim 3, wherein in S2, the coal quality index of the blended coal satisfies: the dry base ash content Ad is 9.90-10.5, the dry ash-free base volatile component Vdaf is 26-30, the dry base total sulfur St is 0.65-0.80, the caking index G is 66.0-70, and the maximum thickness Y of the colloidal layer is 12.5-13.8.

5. The method according to claim 3, wherein in S2, the composition of the blended coal is: 10% of gas coal, 18% of 1/3 coking coal, 6% of gas fat coal, 6% of coking coal No. 1, 14% of coking coal No. 2, 15% of coking coal No. 3, 9% of fat coal, 10% of lean coal, 8% of lean coal and 4% of lignin particles; the total amount of the above components is 100%.

6. The method according to claim 5, wherein in S2, the coal quality index of the blended coal satisfies the following conditions: dry base ash Ad was 9.97, dry no base volatiles Vdaf was 29.28, dry base total sulfur St was 0.71, sticking index G was 69.24, and maximum colloidal layer thickness Y was 13.20.

7. The method of claim 1, wherein in S3, the total moisture content of the blended coal is adjusted to 10% and the bulk density is adjusted to 1 x 10 ³ kg/m ³ Coking for 18h in a coke oven.