Method for preparing high-quality coke for ironmaking by using low-quality coal extract

Abstract

The invention relates to a method for preparing high-quality coke for ironmaking by utilizing low-quality coal extract. The method comprises the following steps: 1) pretreating and extracting low-quality coal; 2) mixing the raw materials; (3) forming and processing; 4) performing high-temperature coking; the crushing strength M40 of the prepared coke is greater than or equal to 89%, the abrasive resistance M10 is less than or equal to 6.5%, and the post-reaction strength CSR is greater than or equal to 68%. According to the invention, high-value conversion of low-quality coal is realized, basic requirements of blast furnace ironmaking on coke quality can be met, and supply of ironmaking raw materials is guaranteed; and meanwhile, the coke performance is improved, the economic benefit of coke production and the resource utilization efficiency are improved, and the utilization approach of low-quality coal is effectively expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical industry, and in particular to a method for preparing high-quality coke for ironmaking by utilizing low-quality coal extract. Background Art

[0002] Among coal resources, low-quality coal is abundant in reserves, but due to its poor cohesiveness, high ash and sulfur content, its application in traditional coking processes is greatly limited. It is mostly used as a low-value fuel, resulting in resource waste and environmental pollution. With the rapid development of the steel industry, the demand for coke quality continues to rise, while high-quality coking coal resources are increasingly scarce. Against this background, exploring new coke preparation methods has become the key to the sustainable development of coking production.

[0003] The currently published literature involves a variety of production methods for steelmaking coke, such as the Chinese invention patent with the authorization announcement number CN110699099 B, which discloses "a method for preparing high-strength coke for ironmaking using chemical waste", which uses pre-grinding, mixing, pressurized granulation, surface spraying, rolling bonding, drying and hardening, and high-temperature coking to prepare high-strength coke for ironmaking, especially using the bonding effect of the precipitate relative to the coke powder during the heating coking process of the carbon-containing waste binder, and the surface-adherent coke powder reduces the burning loss of the granulated material surface during the heating process, so as to achieve high-value reuse of chemical waste such as coke powder and improve the strength and quality of coke. The coke obtained after coking in a high-temperature dry distillation device has a crushing strength M40 ≥ 91.2%, a wear resistance M10 ≤ 5.5%, and a post-reaction strength CSR ≥ 67%, all of which meet the first-level standard of coke for blast furnace ironmaking, realizing the supply of raw materials for ironmaking blast furnaces. Its binder uses asphalt tailings, waste resin chemical waste, etc., and its composition and performance may vary greatly due to different sources. The requirements of softening point ≤140℃, ash content ≤0.5%, and moisture ≤5.0% for chemical waste may be difficult to meet accurately during actual collection and application, which will affect the mixing, granulation and subsequent coke strength formation process, resulting in fluctuations in product quality, and differences in different batches of binders may require frequent adjustments to production process parameters. The process involves multiple steps such as pre-grinding, mixing, pressurized granulation, surface spraying, rolling bonding, drying and hardening, and high-temperature coking, and the process flow is relatively complicated. Each step requires corresponding equipment, such as a crushing grinder, mixer, granulation equipment, oven, high-temperature distillation device, etc., and the equipment investment cost is high. In addition, multi-step operations increase energy consumption, manpower and time costs in the production process, reduce production efficiency, and pose certain challenges to the economy of large-scale industrial production. Moreover, this technical solution mainly utilizes coke powder, coal powder and chemical waste as binders, and does not involve large-scale and full utilization of low-quality coal resources. Compared with this technical solution, the present invention aims to solve the problem that low-quality coal reserves are abundant but its application is limited in traditional coking. Through specific pretreatment and extraction processes, the conversion of low-quality coal into high-quality coke raw materials is achieved. The raw materials are widely available and the overall utilization of low-quality coal resources is higher.

[0004] In summary, in the prior art, there are few studies on the preparation of high-quality ironmaking coke using low-quality coal extracts, and it is difficult to simultaneously meet multiple requirements such as coke strength, reactivity and environmental protection. Therefore, the present invention has important practical significance. Summary of the invention

[0005] The present invention provides a method for preparing high-quality coke for ironmaking by utilizing low-quality coal extracts, thereby realizing high-value conversion of low-quality coal, being able to meet the basic requirements of blast furnace ironmaking on coke quality, and ensuring the supply of ironmaking raw materials; at the same time, it improves the coke performance, enhances the economic benefits and resource utilization efficiency of coke production, and effectively expands the utilization methods of low-quality coal.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing high-quality coke for ironmaking using low-quality coal extracts comprises the following steps:

[0008] 1) Pretreatment and extraction of low-quality coal: crush the low-quality coal, then mix the organic solvent and the low-quality coal in a mass ratio of 3:1 to 5:1, react for 2 to 4 hours at a temperature of 80 to 120° C. and a pressure of 0.5 to 1.5 MPa to perform extraction; after extraction, filter and separate to obtain an extract and an extraction residue, and after distilling the extract to recover the solvent, obtain an extraction concentrate rich in bonding components;

[0009] 2) Raw material mixing: Add the extracted concentrate, coke powder and weakly caking coal into a mixer in the mass percentage of 10% to 20%: 30% to 50%: 30% to 60%; dry mix for 1 to 3 hours, then add 2% to 4% of water accounting for the total mass of the raw materials, and wet mix for 2 to 4 hours to obtain a mixture;

[0010] 3) Molding and processing: The mixed material is pressed into shape by a molding device to obtain a bulk density of 1.0 to 1.3 g / cm 3 , molding materials with compressive strength ≥50kg; drying the molding materials at 60-90℃ for 4-6 hours;

[0011] 4) High-temperature coking: The dried shaped material is placed in a high-temperature dry distillation device under the protection of a nitrogen atmosphere, and the temperature is raised to 900-1050°C at a rate of 5-10°C / min, and kept at this temperature for 8-16 hours to obtain coke.

[0012] In the step 1), the ash content of the low-quality coal is 15% to 30%, the sulfur content is 1.5% to 3.0%, and the volatile content is 25% to 40% by mass.

[0013] In the step 1), the particle size of the crushed low-quality coal is less than 3 mm.

[0014] In the step 1), the organic solvent is toluene or tetrahydrofuran.

[0015] In the step 1), the mass content of the effective bonding component in the extracted concentrate is 60% to 80%.

[0016] In the step 2), the volatile matter of the coke powder is ≤2.0%, the ash content is ≤13.0%, and the sulfur content is ≤0.85% by mass.

[0017] In the step 2), the volatile matter of the weakly caking coal is 20% to 30% by mass, the ash content is ≤12.0%, and the sulfur content is ≤1.0%.

[0018] In the step 3), the molding pressure is 10-30 MPa, and the molding material is a diameter of cylinder.

[0019] In the step 4), the crushing strength M40 of the prepared coke is ≥89%, the abrasion resistance M10 is ≤6.5%, and the post-reaction strength CSR is ≥68%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) Realizes efficient utilization of resources and sustainable development of the industry: The present invention successfully realizes the high-value conversion of low-quality coal, converting low-quality coal, which was originally limited in application due to defects such as poor cohesiveness, high ash content and sulfur content, into high-quality coke raw materials that can be used for blast furnace ironmaking; it greatly expands the effective utilization scope of coal resources, reduces excessive dependence on high-quality coking coal, helps to alleviate the contradiction of unbalanced supply and demand of coal resources, promotes the sustainable development of the coal industry, and opens up a new way for the rational utilization of coal resources;

[0022] 2) Improvement of coke quality and technical support for the steel industry: The coke prepared by the present invention has excellent performance in key performance indicators (including crushing strength, wear resistance, post-reaction strength, etc.), and can fully meet the strict requirements of blast furnace ironmaking on coke quality; in the blast furnace ironmaking process, high-quality coke can maintain good structural stability, effectively reduce the breakage and pulverization rate of coke in the furnace, and ensure good air permeability and liquid permeability of the material column in the blast furnace, thereby ensuring the stability and smoothness of the ironmaking process, improving the output and quality of pig iron, and providing a solid and reliable raw material guarantee for the efficient production of the steel industry;

[0023] 3) Achieved a significant improvement in the economic benefits of production enterprises: From the perspective of production costs, the procurement cost of low-quality coal is relatively low. Compared with the solution of using a large amount of high-quality coking coal in the traditional process, the present invention has obvious advantages in raw material costs, which can greatly reduce the raw material cost expenditure of coke production; although the cost of organic solvent use, equipment upgrades and complex operations is increased in the process, the overall cost is still significantly reduced, effectively improving the profit margin of coke production enterprises; at the same time, high-quality coke is more competitive in the market, which can bring higher sales revenue to the enterprise, further improve the economic benefits of the enterprise, and enhance the competitiveness of the enterprise in the market;

[0024] 4) Achieved outstanding environmental benefits: Through the effective utilization of low-quality coal, the environmental pollution problems caused by the burning of low-quality coal as a low-value fuel or its random stacking are reduced, such as reducing dust emissions and reducing the potential generation of harmful gases such as sulfur oxides and nitrogen oxides; in the coke production process, the generation and emission of waste are reduced by optimizing the process flow and improving the resource conversion rate, which meets the environmental protection requirements, is conducive to promoting the development of coal chemical and steel metallurgical industries towards green and clean production, and achieves a win-win situation of economic and environmental benefits. DETAILED DESCRIPTION

[0025] The method of preparing high-quality coke for ironmaking by using low-quality coal extracts of the present invention comprises the following steps:

[0026] 1) Pretreatment and extraction of low-quality coal: crush the low-quality coal, then mix the organic solvent and the low-quality coal in a mass ratio of 3:1 to 5:1, react for 2 to 4 hours at a temperature of 80 to 120° C. and a pressure of 0.5 to 1.5 MPa to perform extraction; after extraction, filter and separate to obtain an extract and an extraction residue, and after distilling the extract to recover the solvent, obtain an extraction concentrate rich in bonding components;

[0027] 2) Raw material mixing: Add the extracted concentrate, coke powder and weakly caking coal into a mixer in the mass percentage of 10% to 20%: 30% to 50%: 30% to 60%; dry mix for 1 to 3 hours, then add 2% to 4% of water accounting for the total mass of the raw materials, and wet mix for 2 to 4 hours to obtain a mixture;

[0028] 3) Molding and processing: The mixed material is pressed into shape by a molding device to obtain a bulk density of 1.0 to 1.3 g / cm 3 , molding materials with compressive strength ≥50kg; drying the molding materials at 60-90℃ for 4-6 hours;

[0029] 4) High-temperature coking: The dried shaped material is placed in a high-temperature dry distillation device under the protection of a nitrogen atmosphere, and the temperature is raised to 900-1050°C at a rate of 5-10°C / min, and kept at this temperature for 8-16 hours to obtain coke.

[0030] In the step 1), the ash content of the low-quality coal is 15% to 30%, the sulfur content is 1.5% to 3.0%, and the volatile content is 25% to 40% by mass.

[0031] In the step 1), the particle size of the crushed low-quality coal is less than 3 mm.

[0032] In the step 1), the organic solvent is toluene or tetrahydrofuran.

[0033] In the step 1), the mass content of the effective bonding component in the extracted concentrate is 60% to 80%.

[0034] In the step 2), the volatile matter of the coke powder is ≤2.0%, the ash content is ≤13.0%, and the sulfur content is ≤0.85% by mass.

[0035] In the step 2), the volatile matter of the weakly caking coal is 20% to 30% by mass, the ash content is ≤12.0%, and the sulfur content is ≤1.0%.

[0036] In the step 3), the molding pressure is 10-30 MPa, and the molding material is a diameter of cylinder.

[0037] In the step 4), the crushing strength M40 of the prepared coke is ≥89%, the abrasion resistance M10 is ≤6.5%, and the post-reaction strength CSR is ≥68%.

[0038] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0039] [Example]

[0040] The low-quality coal extraction process parameters of each embodiment are shown in Table 1, the raw material mixing process parameters of each embodiment are shown in Table 2, the molding process parameters of each embodiment are shown in Table 3, and the coking process parameters and coke properties of each embodiment are shown in Table 4.

[0041] Table 1 Low-quality coal extraction process parameters

[0042]

[0043] Table 2 Raw material mixing process parameters

[0044]

[0045] Table 3 Molding process parameters

[0046]

[0047] Table 4 Coking process parameters and coke properties

[0048]

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing high-quality coke for ironmaking using low-quality coal extracts, characterized in that: The steps include: 1) Pretreatment and extraction of low-quality coal: crush the low-quality coal, then mix the organic solvent and the low-quality coal in a mass ratio of 3:1 to 5:1, react for 2 to 4 hours at a temperature of 80 to 120° C. and a pressure of 0.5 to 1.5 MPa to perform extraction; after extraction, filter and separate to obtain an extract and an extraction residue, and after distilling the extract to recover the solvent, obtain an extraction concentrate rich in bonding components; 2) Raw material mixing: Add the extracted concentrate, coke powder and weakly caking coal into a mixer in the mass percentage of 10% to 20%: 30% to 50%: 30% to 60%; dry mix for 1 to 3 hours, then add 2% to 4% of water accounting for the total mass of the raw materials, and wet mix for 2 to 4 hours to obtain a mixture; 3) Molding and processing: The mixed material is pressed into shape by a molding device to obtain a bulk density of 1.0 to 1.3 g / cm 3 , molding materials with compressive strength ≥50kg; drying the molding materials at 60-90℃ for 4-6 hours; 4) High-temperature coking: The dried shaped material is placed in a high-temperature dry distillation device under the protection of a nitrogen atmosphere, and the temperature is raised to 900-1050°C at a rate of 5-10°C / min, and kept at this temperature for 8-16 hours to obtain coke.

2. A method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 1), the ash content of the low-quality coal is 15% to 30%, the sulfur content is 1.5% to 3.0%, and the volatile content is 25% to 40% by mass.

3. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 1), the particle size of the crushed low-quality coal is less than 3 mm.

4. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 1), the organic solvent is toluene or tetrahydrofuran.

5. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 1), the mass content of the effective bonding component in the extracted concentrate is 60% to 80%.

6. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 2), the volatile matter of the coke powder is ≤2.0%, the ash content is ≤13.0%, and the sulfur content is ≤0.85% by mass.

7. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 2), the volatile matter of the weakly caking coal is 20% to 30% by mass, the ash content is ≤12.0%, and the sulfur content is ≤1.0%.

8. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 3), the molding pressure is 10-30 MPa, and the molding material is a diameter of cylinder.

9. The method for preparing high-quality coke for ironmaking using low-quality coal extract according to claim 1, characterized in that: In the step 4), the crushing strength M40 of the prepared coke is ≥89%, the abrasion resistance M10 is ≤6.5%, and the post-reaction strength CSR is ≥68%.

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