Coking coal blending method

Abstract

The invention discloses a coking coal blending method in the technical field of coal coking. The method comprises the following steps: firstly, mixing high-sulfur fat coal, coking coal, weakly caking coal, gas fat coal, gas coal, lean coking coal and meager lean coal according to a specific proportion and crushing; premixing a very small amount of the plasma functionalized hierarchical zeolite-carbon nanotube core-shell structure complex with a small amount of mixed coal to prepare a master batch, and uniformly mixing the master batch with the rest of the mixed coal; and finally charging the obtained modified blended coal into a furnace for carbonization. The complex is prepared through a plurality of processes including zeolite ion exchange and crystallization, chemical vapor deposition growth of a carbon nanotube shell layer, oxygen plasma surface functionalization, magnesium-lithium composite oxide loading and the like. According to the invention, the complex is introduced into low-cost blended coal, and the dual functions of nano enhancement and catalytic sulfur fixation of the complex are utilized, so that the consumption of high-price coking coal is remarkably reduced, the microstructure of coke is synergistically optimized, the sulfur content is reduced, and the synergistic improvement of coking cost and coke quality is realized.

Description

Technical Field

[0001] This invention belongs to the field of coal coking technology, specifically relating to a method for coking coal blending. Background Technology

[0002] Coking is an indispensable and crucial link in the iron and steel metallurgical industry. Its core task is to convert blended coal into metallurgical coke through high-temperature dry distillation, providing fuel, reducing agent, and a structural support for blast furnace smelting. Traditional coking coal blending technology heavily relies on high-quality coking coal and fat coal with strong caking properties to ensure that the coke has sufficient cold strength and hot performance. However, the increasing scarcity and soaring prices of high-quality coking coal resources globally have placed enormous pressure on coking production costs. At the same time, increasingly stringent environmental regulations have imposed higher standards on coke product quality, especially sulfur content. This creates a prominent contradiction: increasing the proportion of high-priced, strong-caking coal to improve coke strength not only directly drives up costs but also often results in coke products with excessive sulfur content due to the high sulfur content of this type of coal. Therefore, how to significantly reduce coal blending costs and effectively control sulfur content while ensuring or even improving the mechanical strength and post-reaction strength of coke has become a core technical challenge that the coking industry urgently needs to solve.

[0003] To address these challenges, existing technologies are primarily explored in two directions. On one hand, by optimizing coal blending models and meticulously utilizing coal petrology indicators, attempts are made to introduce more inexpensive, weakly caking or non-caking coal into the blending structure to replace some of the high-priced coal. However, this method has a clear performance ceiling; excessive use of low-quality coal deteriorates the microstructure of coke, leading to a significant decrease in strength and thermal properties. On the other hand, researchers are attempting to add various modifiers or catalysts to the coal blend to improve the coking properties of the coal. These additives include inorganic minerals, industrial waste, or organic binders, which function either by regulating the pyrolysis process or by providing binding components. However, most traditional additives have limited functionality and effects, and may fail, decompose, or introduce harmful impurities under high-temperature carbonization conditions. They cannot achieve precise control over the nanoscale structure of coke or the directional fixation of sulfur, making it difficult to strike a balance between cost and quality.

[0004] Against this backdrop, recent advances in materials science and nanotechnology have provided novel insights into the innovation of coking coal blending. Research indicates that nanomaterials with specific structures can profoundly influence the thermal conversion pathways and final product structures of carbonaceous materials through their unique size and surface effects. For example, porous zeolite materials, due to their regular channels and tunable acidic sites, exhibit shape-selective catalytic potential for pyrolysis intermediates; carbon nanotubes, as one-dimensional nanomaterials, have been proven to effectively enhance the mechanical properties of composite materials; and low-temperature plasma technology can precisely modify material surfaces, significantly improving their dispersibility and interfacial bonding capabilities. However, how to creatively integrate these discrete materials science and catalytic principles into a novel modifier specifically designed for the coking process with multiple composite functions, and systematically combine it with a coal blending scheme aimed at maximizing the utilization of low-cost coal types, thereby constructing a complete technical system from microscopic modification to macroscopic performance enhancement, has not yet been reported in existing technologies. This invention is based on this innovative concept and aims to overcome the limitations of traditional coal blending technologies. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for coking coal blending.

[0006] A first aspect of the present invention provides a method for coking coal blending, comprising the following steps: S1. By weight, 3-8 parts of high-sulfur fat coal, 12-16 parts of coking coal, 28-35 parts of weakly caking coal, 8-12 parts of gas-rich fat coal, 15-18 parts of gas coal, 0-20 parts of lean coking coal, and 0-25 parts of lean coal are fed into a crusher to be crushed to obtain blended coal. S2. The plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell structure composite is premixed with 5-10% of the blended coal in step S1 in a mixer to obtain the masterbatch. S3. Mix the masterbatch with 90-95% of the blended coal by mass as described in step S1 in a mixer to obtain modified blended coal; S4. The modified blended coal is loaded into the coke oven and heated for carbonization.

[0007] In this invention, the plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell composite is added in a trace amount through a two-step mixing process of premixed masterbatch and main coal, ensuring uniform molecular-scale dispersion in the macroscopically blended coal. During carbonization, the carbon nanotube shell, with its ultra-high strength and excellent thermal conductivity, acts as a nano-reinforcing framework embedded in the coke matrix, effectively bridging aromatic free radical fragments generated by coal pyrolysis and guiding their orderly stacking and condensation, significantly enhancing the continuity and structural density of the coke microstructure. The composite metal oxides loaded within the zeolite core remain stable at the high temperature of carbonization, and their alkaline surface catalyzes the directional condensation reaction of free radicals, optimizing the anisotropic development of the coke microstructure. Simultaneously, it synergistically forms a highly efficient adsorption network with the multi-level porous structure, converting the sulfur-containing gases released by thermal decomposition into stable sulfides and retaining them within the pores through acid-base neutralization and chemical fixation, significantly reducing the sulfur content of the coke. The three-dimensional thermally conductive network constructed by carbon nanotubes promotes uniform heat transfer, alleviates the temperature difference between the inside and outside of the coke cake, and inhibits thermal stress cracking. The zeolite mesoporous structure provides additional gas diffusion channels and synergistically regulates the pore distribution. Ultimately, through the synergistic effect of multiple mechanisms including physical enhancement, chemical catalysis, and adsorption desulfurization, this composite systemically improves the post-reaction strength of coke, reduces sulfur content, and optimizes pore structure at extremely low addition levels. This provides a green technology path for the clean and efficient utilization of high-sulfur coal resources, avoiding the high energy consumption and secondary pollution problems of traditional desulfurization processes, and demonstrating the value of the deep integration of material design and process innovation.

[0008] According to a preferred embodiment of the present invention, in step S1, the proportion of particles with a particle size <3mm in the blended coal is 78-82%.

[0009] According to a preferred embodiment of the present invention, in step S2, the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell structure composite accounts for 0.1-0.5% of the total mass of the blended coal.

[0010] According to a preferred embodiment of the present invention, in step S3, the mixing time is 8-15 min.

[0011] According to a preferred embodiment of the present invention, in step S4, the coke cake center temperature during the carbonization process is 1000-1050℃, and the coking time is 16-20h.

[0012] According to a preferred embodiment of the present invention, the preparation steps of the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell structure composite include: A1. By weight, 18-22 parts of NaY zeolite are dispersed in 180-220 parts of a mixed aqueous solution of lanthanum nitrate and calcium nitrate, and stirred at 78-82℃ to obtain a mixture; the mixture is centrifuged to obtain a solid, and the solid is washed with deionized water to obtain a washed wet filter cake; the washed wet filter cake is redispersed in 180-220 parts of deionized water, and 1.4-1.6 parts of citric acid are added, and crystallization is carried out in a high-pressure reactor at 145-155℃; after natural cooling, the solid is collected by centrifugation, and the solid is washed with deionized water and calcined in a muffle furnace at 545-555℃ under an air atmosphere to obtain multi-level porous zeolite; A2. The multi-level porous zeolite was immersed in a nickel nitrate ethanol solution, dried, and then reduced in a hydrogen atmosphere at 395-405℃. It was then transferred to a CVD furnace and heated to 645-655℃ under argon protection. A mixture of ethylene, hydrogen, and argon was introduced to react the mixture, and the mixture was cooled to obtain a zeolite-carbon nanotube core-shell intermediate. A3. The zeolite-carbon nanotube core-shell intermediate was placed in a plasma treatment instrument, vacuumed, oxygen was introduced, and plasma treatment was performed; vacuum cooling was then performed to obtain a functional material with oxygen-containing functional groups on the surface. A4. Dissolve magnesium nitrate hexahydrate and lithium nitrate trihydrate in deionized water to obtain an impregnation solution; place the functional material with oxygen-containing functional groups on the surface in the impregnation solution, disperse it ultrasonically at 24-26℃, and let it stand for impregnation; after impregnation, filter to obtain a solid, place the solid in a forced-air drying oven, dry it at 58-62℃ to obtain a dried precursor powder, place the dried precursor powder in a muffle furnace, heat it to 490-510℃, calcine it in an air atmosphere, cool it, grind and sieve it.

[0013] In this invention, the construction of the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composite originates from a multi-scale interface precision control strategy. Starting with commercially available sodium-type zeolite as a substrate, lanthanum and calcium ions are selectively embedded into the zeolite framework through liquid-phase ion exchange, while citric acid is simultaneously introduced. After hydrothermal crystallization and calcination, a hierarchical porous carrier with interconnected micropores and mesopores is formed, significantly improving the specific surface area and structural stability. Subsequently, nickel-based catalytic centers are loaded, promoting in-situ pyrolysis and self-assembly of carbon source molecules on the zeolite surface during vapor deposition, growing a carbon nanotube shell that combines with zeolite particles to form a core-shell structure. To further enhance interfacial compatibility, oxygen plasma is used to activate the carbon nanotube surface. High-energy reactive oxygen species bombard the surface, introducing hydrophilic functional groups such as carboxyl and hydroxyl groups, significantly improving its dispersion ability and subsequent loading efficiency in an aqueous environment. Finally, through an impregnation-calcination process, the magnesium-lithium precursor is transformed into a highly dispersed composite metal oxide, which is firmly anchored on the inner wall of the zeolite mesopores and the surface of carbon nanotubes. This achieves a three-in-one integration of multi-level pore adsorption, surface functionalization, and bimetallic oxide catalytic activity, providing a structurally stable and functionally synergistic nanoscale functional unit for the coking process.

[0014] According to a preferred embodiment of the present invention, in step A1, the calcination time in an air atmosphere is 4-6 hours.

[0015] According to a preferred embodiment of the present invention, in step A2, the reduction time under a hydrogen atmosphere at 395-405°C is 2-4 hours.

[0016] According to a preferred embodiment of the present invention, in step A3, the plasma treatment time is 15-30 min.

[0017] According to a preferred embodiment of the present invention, in step A4, the calcination time in an air atmosphere is 4-6 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The most outstanding effect of this invention is that it achieves a significant reduction in coking coal blending costs and a simultaneous improvement in coke quality, breaking the traditional dilemma of "cost reduction inevitably leads to quality reduction". Through a carefully designed coal blending scheme, the proportion of low-priced weakly caking coal and gas coal is greatly increased, significantly reducing the dependence on expensive prime coking coal and fat coal, thus reducing raw material costs from the source. The carbon nanotube shell in the plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell structure composite acts as a nano-reinforcing skeleton during coke formation, embedding into the carbon matrix and bridging microcracks, directly strengthening the microstructure of coke, thereby ensuring or even improving the mechanical strength and post-reaction strength of coke on the basis of low-cost coal blending. This "low-quality coal + high-performance additives" model provides a new economical and efficient path for the coking industry.

[0019] (2) This invention possesses excellent targeted desulfurization and environmental protection effects, effectively solving the problem of utilizing high-sulfur coal. Traditional methods often force the abandonment of high-sulfur but highly caking coal types or require costly pretreatment to reduce sulfur content. In this invention, the core-shell structure design of the plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell composite endows it with active sulfur fixation capabilities. The specific metal oxides loaded in its core are stable at high carbonization temperatures and can preferentially undergo chemical adsorption or reaction with the sulfur-containing gases released by coal thermal decomposition, converting them into stable solid sulfides and fixing them in the inert components of coke. This means that this invention allows the incorporation of a certain proportion of high-sulfur coking coal to utilize its strong caking properties without worrying about excessive sulfur content in the final coke product, achieving clean and efficient utilization of high-sulfur resources while meeting stringent environmental protection requirements.

[0020] (3) The plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell composite preparation method provided by this invention is scientific and functionally controllable. Its multi-layer composite structure ensures the stability and reliability of the final effect. This material is not a simple mixture, but achieves functional division and synergy by constructing a stable configuration of "zeolite core-carbon nanotube shell". The zeolite core not only provides a high specific surface area and abundant loading sites, but its multi-level pores also facilitate the mass transfer of reactants; the external carbon nanotube network not only strengthens the mechanical and thermal stability of the overall structure, but its surface after plasma activation is also easier to disperse in coal particles and generate interfacial bonding. The final loaded metal oxide active components are highly dispersed and firmly anchored, and are not easily sintered and deactivated in the complex coking process. This rigorous step-by-step preparation process ensures that each functional unit can survive and work effectively in the extreme environment of high-temperature carbonization, thereby ensuring the repeatability and long-term effectiveness of the method of this invention in industrial applications. Detailed Implementation

[0021] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention. Example

[0022] This embodiment provides a method for coking coal blending, including the following steps: S1. Accurately weigh 30g of high-sulfur coking coal, 140g of coking coal, 320g of weakly caking coal, 100g of gas-rich coking coal, 160g of gas coal, 100g of lean coking coal, and 70g of semi-lean coal. Feed all the coal materials together into a jaw crusher for coarse crushing, then transfer them to a roller crusher for fine crushing. Use a standard sieve set to screen and analyze the crushed coal. By controlling the crusher gap and crushing time, ensure that particles smaller than 3mm account for 80.0% of the total mass of the resulting blended coal. The blended coal is then obtained.

[0023] S2. Accurately weigh 2.76 g of the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composite. Also accurately weigh 64.4 g of the blended coal prepared in step S1. Place the composite and blended coal together in a 1 L laboratory-grade small V-type mixer. Set the mixer speed to 30 rpm and start the mixer for premixing for 4 minutes to obtain a uniformly dispersed, high-concentration masterbatch.

[0024] S3. Add all the masterbatch obtained in step S2 and the remaining blended coal from step S1 into a horizontal twin-shaft paddle mixer. Set the mixer speed to 60 rpm, control the material filling volume to 60% of the total mixer volume, and start the mixer for intensive mixing for 10 minutes. During the mixing process, pause at the 2nd, 5th, and 8th minutes, and manually scrape off the material adhering to the mixer drum wall and paddle shaft using a scraper to ensure absolute uniformity of mixing. After mixing, the modified blended coal is obtained.

[0025] S4. The modified blended coal obtained in step S3 was added in three batches to a cylindrical stainless steel simulated coke pot with an inner diameter of 100 mm and a height of 300 mm, pre-coated with a release agent. After each addition, the coal was compacted using a press at a pressure of 10 MPa. The final coal bulk density was controlled to be 1.05 g / cm³. The coke pot was placed in a preheated experimental coke oven, and carbonization was carried out according to the following heating regime: first, the temperature was increased from room temperature to 800℃ at a rate of 3℃ / min, then increased to 1025℃ at a rate of 2℃ / min (this was used as the target temperature for the coke cake center), and held at 1025℃ for 30 min. The total time from room temperature to 1025℃ and the time to maintain this temperature, i.e., the coking time, was 18 hours. After carbonization, the coke was cooled to below 150℃ using a dry quenching process, and the blocky metallurgical coke was removed.

[0026] Preparation steps of plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composites: A1. Using an analytical balance with an accuracy of 0.001 g, weigh 20.00 g of commercially available NaY zeolite and place it in a 500 mL polytetrafluoroethylene beaker. Measure 200 mL of a 1.2 mol / L mixed aqueous solution of lanthanum nitrate and calcium nitrate (where La... 3+ With Ca 2+The molar ratio of the ions was 3:1, and the mixture was added to a beaker. The beaker was placed in a constant temperature water bath at 80.0℃, and a magnetic stirrer was used to stir vigorously at a speed of 500 rpm for 6 hours to complete the ion exchange process. The exchanged suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 minutes. The supernatant containing excess metal ions was carefully discarded. 200 mL of deionized water was added to the solid precipitate in the centrifuge tube, and the mixture was redispersed into a suspension using a vortex mixer. The suspension was then centrifuged again under the same conditions. This "dispersion-centrifugation" washing operation was repeated, and the conductivity of the supernatant obtained after each centrifugation was measured in real time using a portable conductivity meter until the conductivity reading of the final wash solution stabilized at 45 μS / cm, indicating that the free ions had been completely removed. The wet filter cake after the final washing was transferred to a 500 mL high-pressure reactor with a polytetrafluoroethylene liner, 200 mL of deionized water was added, and then 1.500 g of citric acid was precisely added as a mesoporous structure directing agent. Stir manually for 5 minutes to ensure initial homogeneity of the system. Seal the reactor and place it in a forced-air drying oven at 150℃ for hydrothermal crystallization for 12 hours. After crystallization, allow the reactor to cool naturally to room temperature inside the oven. Open the reactor and transfer all the product to centrifuge tubes. Wash the product with deionized water until the supernatant is neutral (tested with pH paper). Transfer the washed solid to an alumina crucible and place it in a box-type muffle furnace. Under static air atmosphere, increase the temperature from room temperature to 550℃ at a programmed rate of 3℃ / min, and calcine at 550℃ for 4 hours. After calcination, cool the furnace to below 100℃, remove the product, grind it, and obtain a La-rich product. 3+ / Ca 2+ Multi-level porous zeolite with active sites is placed in a desiccator for later use.

[0027] A2. Accurately weigh 10.00 g of the multi-porous zeolite prepared in step A1 and place it in a clean 250 mL Erlenmeyer flask. Measure 100 mL of a 0.5 mol / L nickel nitrate ethanol solution and add it to the Erlenmeyer flask, ensuring the zeolite is completely submerged. Seal the flask opening with sealing film and allow it to stand at room temperature (25°C) for 12 h. After impregnation, separate the zeolite by suction filtration using a Buchner funnel and filter paper. Transfer the filter cake to a watch glass and dry it in a forced-air drying oven at 60°C for 4 h until the mass is constant, obtaining a dry powder loaded with the nickel precursor. Spread the dried powder evenly in a quartz boat and push it into the isothermal zone of a tube furnace. First, introduce high-purity hydrogen gas at a flow rate of 100 mL / min for 30 min to completely replace the air in the furnace tubes. Subsequently, under a hydrogen atmosphere, the temperature was increased to 400℃ at a heating rate of 5℃ / min, and maintained at 400℃ for 2 hours to completely decompose nickel nitrate into catalytically active metallic nickel nanoparticles. After reduction, the hydrogen gas was turned off, and high-purity argon gas at a flow rate of 200 mL / min was used as a protective gas, allowing the sample to cool naturally to room temperature under argon protection. The zeolite powder loaded with the nickel catalyst was transferred to a quartz boat specifically designed for chemical vapor deposition (CVD) furnaces and pushed into the furnace tube isothermal zone. Argon gas at a flow rate of 200 mL / min was introduced as both a protective and carrier gas, and the furnace temperature was increased to 650℃ at a heating rate of 10℃ / min and stabilized. Subsequently, the reaction gas was switched to a specific mixture: ethylene flow rate of 100 sccm, hydrogen flow rate of 50 sccm, and argon flow rate maintained at 200 sccm. Under these conditions, the reaction was carried out for 40 minutes, allowing ethylene to decompose on the surface of the nickel catalyst and grow carbon nanotubes. After the reaction was completed, the ethylene and hydrogen valves were immediately closed, the argon flow rate was kept at 200 mL / min, the sample was cooled to below 80 °C and then removed to obtain the zeolite-carbon nanotube core-shell intermediate.

[0028] A3. Weigh 5.00 g of the zeolite-carbon nanotube core-shell intermediate prepared in step A2, and use a soft brush to evenly and monolayer it onto the circular quartz sample tray of the plasma processor. Close the reaction chamber door, start the mechanical pump and molecular pump, and pump the pressure inside the chamber to 5 × 10⁻⁶. -2 High-purity oxygen was slowly introduced into the chamber using a mass flow controller, and the working pressure was precisely controlled at 30 Pa. The radio frequency power supply was turned on, the discharge power was set to 150 W, and the frequency to 13.56 MHz, and plasma discharge was initiated to treat the sample surface for 20 minutes. During the treatment, a pale blue glow was observed in the chamber. After the treatment, the radio frequency power supply and oxygen supply were turned off sequentially, and the vacuum system was maintained to allow the sample to cool in a vacuum environment for 15 minutes. Subsequently, argon gas was slowly introduced into the chamber to atmospheric pressure, the chamber was opened, and the sample was removed, yielding a functionalized material with a surface rich in oxygen-containing functional groups such as carboxyl and hydroxyl groups.

[0029] A4. Accurately weigh 7.690 g of magnesium nitrate hexahydrate and 2.065 g of lithium nitrate trihydrate using an analytical balance, dissolve them together in 50 mL of deionized water, and stir on a magnetic stirrer until completely transparent to prepare an impregnation solution with a total metal ion concentration of 1.5 mol / L, in which Mg... 2+ With Li + The molar ratio was 2:1. 10.00 g of the surface-functionalized oxygen-containing material prepared in step A3 was weighed and placed in the impregnation solution. The container was placed in an ultrasonic cleaner and ultrasonically dispersed for 30 min at 300 W power and 40 kHz frequency at 25°C to ensure sufficient contact between the material and the impregnation solution. The system was then allowed to stand and impregnate for another 12 h at room temperature. After impregnation, the mixture was filtered using a Buchner funnel, and the filter cake was rinsed twice with a small amount of deionized water to remove residual impregnation solution. The filter cake was transferred to a petri dish and dried in a 60°C forced-air drying oven for 12 h until its mass no longer changed, yielding dried magnesium nitrate / lithium nitrate precursor powder. This powder was loaded into an alumina boat and placed in a box-type muffle furnace. Dry air was introduced at a flow rate of 80 mL / min to create a flowing air atmosphere. The furnace temperature was raised to 500℃ at a programmed heating rate of 3℃ / min, and calcined at 500℃ for 4 hours to ensure complete decomposition of the nitrate precursor into highly dispersed magnesium oxide and lithium oxide composite metal oxides. After calcination, the furnace was cooled to room temperature, the product was removed, ground in an agate mortar, and finally passed through a 300-mesh standard sieve to obtain plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composite powder, which was stored in a desiccator for later use. Example

[0030] The difference between this embodiment and Embodiment 1 lies in the preparation steps of the coking coal blending method: S1. Accurately weigh 50g of high-sulfur coking coal, 120g of coking coal, 350g of weakly caking coal, 80g of gas-rich coking coal, 180g of gas coal, 80g of lean coking coal, and 100g of semi-lean coal. Crush all coal materials using a crusher and then screen them, controlling the proportion of particles smaller than 3mm in the resulting blended coal to be 78.0%. The blended coal is then obtained.

[0031] S2. Accurately weigh 1.92g of plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell structure composite, and premix it with 76.8g of blended coal in a V-type mixer at a speed of 30rpm for 3min to obtain the masterbatch.

[0032] S3. Add all the masterbatch obtained in step S2 and the remaining blended coal to a twin-shaft paddle mixer, set the speed to 60 rpm, mix for 12 minutes, pause at the 4th minute and the 8th minute and manually scrape the material to obtain modified blended coal.

[0033] S4. Using a top-loading process, the modified blended coal is loaded into a simulated coke pot in one go. The coal bulk density is controlled to be 0.85 g / cm³ by tapping and compaction. The coke pot is then placed in an experimental coke oven and carbonized according to the following regime: the temperature is increased to 800℃ at 3℃ / min, then increased to 1000℃ (coke cake center temperature) at 2℃ / min and held at that temperature for 30 min. The total coking time is 20 h. Coke is obtained after dry quenching.

[0034] Preparation steps of plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composites: A1. Weigh 18.00g of NaY zeolite and disperse it in 180mL of a 1.0mol / L La solution. 3+ :Ca 2+ A mixture of lanthanum nitrate and calcium nitrate in a molar ratio of 2.5:1 was stirred at 500 rpm for 7 h in a water bath at 78.0 °C. After centrifugation, the solid precipitate was repeatedly washed with deionized water until the conductivity of the final wash solution was 40 μS / cm. The wet filter cake was redispersed in 180 mL of deionized water, 1.400 g of citric acid was added, and the mixture was placed in an autoclave and crystallized at 145 °C for 13 h. After cooling, the mixture was centrifuged and washed until neutral. The solid was then calcined in air at a rate of 2 °C / min to 545 °C for 5 h to obtain hierarchical porous zeolite.

[0035] A2. 10.00 g of hierarchical porous zeolite was impregnated in 100 mL of 0.4 mol / L nickel nitrate ethanol solution for 14 h. After filtration and drying, the sample was reduced at 395 °C at a rate of 5 °C / min under a hydrogen atmosphere (100 mL / min) for 2.5 h. The reduced sample was then transferred to a CVD furnace and heated to 645 °C under argon protection. A mixed gas with a flow rate ratio of C2H4:H2:Ar = 90:45:180 (sccm) was introduced and reacted for 50 min. After cooling, a core-shell intermediate was obtained.

[0036] A3. Place 5.00g of the core-shell intermediate in a plasma treatment instrument, evacuate to 8Pa, then introduce oxygen, controlling the pressure at 20Pa. Perform oxygen plasma treatment at 120W power and 13.56MHz frequency for 25min, and remove the sample after vacuum cooling.

[0037] A4. Weigh 5.128 g of magnesium nitrate hexahydrate and 4.199 g of lithium nitrate trihydrate, dissolve them in 50 mL of water to prepare a total metal ion concentration of 1.0 mol / L (Mg). 2+ :Li +A 1:1 impregnation solution was prepared. 10.00 g of the material obtained in step A3 was impregnated and ultrasonically dispersed (300 W, 40 kHz) at 24 °C for 25 min, followed by standing impregnation for 14 h. After filtration and drying, the precursor powder was calcined in a muffle furnace at 490 °C with air at a flow rate of 50 mL / min and a temperature increase of 2 °C / min, and held at that temperature for 5 h. After cooling, it was ground through a 300-mesh sieve to obtain the composite. Example

[0038] The difference between this embodiment and Embodiment 1 lies in the preparation steps of the coking coal blending method: S1. Accurately weigh 80g of high-sulfur coking coal, 160g of coking coal, 280g of weakly caking coal, 120g of gas-rich coking coal, 150g of gas coal, 120g of lean coking coal, and 50g of semi-lean coal. Crush all the coal materials and sieve them, controlling the mass ratio of particles smaller than 3mm in the resulting blended coal to be 82.0%. The blended coal is then obtained.

[0039] S2. Accurately weigh 4.80g of plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell structure composite, and premix it with 48.0g of blended coal in a V-type mixer at a speed of 30rpm for 5min to obtain the masterbatch.

[0040] S3. Add all the masterbatch obtained in step S2 and the remaining blended coal to a twin-shaft paddle mixer, set the speed to 60 rpm, mix for 8 minutes, pause at the 2nd minute and the 5th minute and manually scrape the material to obtain modified blended coal.

[0041] S4. The coke was loaded into the furnace using a tamping process, controlling the bulk density to 1.05 g / cm³. The coke can was placed in the experimental coke oven and carbonized according to the following procedure: the temperature was increased to 800℃ at 3℃ / min, then increased to 1050℃ (the center temperature of the coke cake) at 2℃ / min and held at that temperature for 30 min, for a total coking time of 16 h. Coke was obtained after dry quenching.

[0042] Preparation steps of plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composites: A1. Weigh 22.00g of NaY zeolite and disperse it in 220mL of a 1.5mol / L La solution. 3+ :Ca 2+ A mixture of lanthanum nitrate and calcium nitrate in a 3:1 molar ratio was stirred at 500 rpm for 5 h in a water bath at 82.0 °C. After centrifugation, the solid precipitate was repeatedly washed with deionized water until the conductivity of the final wash solution was 50 μS / cm. The wet filter cake was redispersed in 220 mL of deionized water, 1.600 g of citric acid was added, and the mixture was placed in an autoclave and crystallized at 155 °C for 11 h. After cooling, the mixture was centrifuged and washed until neutral. The solid was then calcined in air at a rate of 5 °C / min to 555 °C for 3 h to obtain hierarchical porous zeolite.

[0043] A2. 10.00 g of hierarchical porous zeolite was impregnated in 100 mL of 0.6 mol / L nickel nitrate ethanol solution for 10 h. After filtration and drying, the sample was reduced at 405 °C at a hydrogen atmosphere of 100 mL / min and a constant temperature of 5 °C / min for 1.5 h. The reduced sample was transferred to a CVD furnace and heated to 655 °C under argon protection. A mixed gas with a flow rate ratio of C2H4:H2:Ar = 110:55:220 (sccm) was introduced and reacted for 30 min. After cooling, a core-shell intermediate was obtained.

[0044] A3. Place 5.00g of the core-shell intermediate in a plasma treatment instrument, evacuate to 3Pa, then introduce oxygen, controlling the pressure at 50Pa. Perform oxygen plasma treatment at 180W power and 13.56MHz frequency for 15min, and remove the sample after vacuum cooling.

[0045] A4. Weigh 15.380 g of magnesium nitrate hexahydrate and 2.065 g of lithium nitrate trihydrate, dissolve them in 50 mL of water to prepare an impregnation solution with a total metal ion concentration of 2.0 mol / L (Mg²⁺:Li⁺=3:1). Immerse 10.00 g of the material obtained in step A3 into the solution, and disperse it ultrasonically (300 W, 40 kHz) at 26 °C for 35 min, then allow it to stand for 10 h. After filtration and drying, calcine the precursor powder in a muffle furnace at a flow rate of 100 mL / min in air at a rate of 5 °C / min to 510 °C, and maintain this temperature for 3 h. After cooling, grind the powder through a 300-mesh sieve to obtain the composite.

[0046] Comparative Example 1 The difference between this comparative example and Example 1 is that the same type and quality of coal were used. All coal types were crushed to a particle size of less than 3 mm, with 80% of the particles being smaller than 3 mm, to obtain a blended coal. Without adding plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell composite material, all the blended coal was directly fed into a twin-shaft paddle mixer and mixed at 60 rpm for 10 minutes. Subsequently, coking was carried out using the same compaction process (bulk density 1.05 g / cm³) and carbonization regime as in Example 1 (coke cake center temperature 1025℃, coking time 18 h) to obtain metallurgical coke.

[0047] Comparative Example 2 The difference between this comparative example and Example 1 is that the same type and quality of coal as in Example 1 were used and crushed to the same fineness. A comparative modifier was prepared: the steps were exactly the same as steps A1, A2, and A4 in the preparation of the composite in Example 1, but the oxygen plasma treatment in step A3 was completely omitted. That is, multi-level porous zeolite was first prepared according to the method of Example 1, and then carbon nanotubes were grown by chemical vapor deposition to obtain a core-shell intermediate. Subsequently, the intermediate was directly loaded with magnesium-lithium composite oxide in step A4 to finally obtain the comparative material without physical surface functionalization. 2.76 g of this comparative material was taken and premixed with 64.4 g of blended coal for 4 min to obtain a masterbatch, and then mixed with the remaining blended coal for 10 min. Coking was carried out using the same tamping process and carbonization regime as in Example 1 to obtain metallurgical coke.

[0048] Comparative Example 3 The difference between this comparative example and Example 1 is that the same type and mass of coal as in Example 1 were used and crushed to the same fineness. Another comparative modifier was prepared: its steps only included steps A1, A2, and A3 of the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell composite preparation steps in Example 1, but completely omitted the impregnation and calcination loading in step A4. That is, hierarchical porous zeolite was first prepared according to the method of Example 1, and then carbon nanotubes were grown by chemical vapor deposition to obtain a core-shell intermediate. Subsequently, the intermediate was treated with oxygen plasma to obtain a pure carbon nanotube-zeolite core-shell material with surface functionalization but without any metal oxide loading. 2.76 g of this comparative material was taken and premixed with 64.4 g of blended coal for 4 min to obtain a masterbatch, which was then mixed with the remaining blended coal for 10 min. Coking was carried out using the same tamping process and carbonization regime as in Example 1 to obtain metallurgical coke.

[0049] In accordance with national and industry standard testing specifications, a series of standardized tests were conducted on the coking coal blending methods described in Examples 1-3 and Comparative Examples 1-3.

[0050] The cold mechanical strength test of coke was conducted using a Mikum drum. From each coke sample, regularly shaped coke lumps without obvious cracks were manually selected, and coke lumps with a particle size greater than 40 mm were sieved using a standard square-hole sieve for later use. 50.0 kg of this coke sample was accurately weighed and loaded entirely into the Mikum drum. The drum door was closed, and the drum was started, rotating at a constant speed of 25 r / min for 100 revolutions, for a total time of 4 minutes. After rotation, all the coke was removed from the drum, and the product was sieved using a mechanical shaking sieve and a set of standard square-hole sieves (40 mm and 10 mm apertures respectively). The mass of the three coke fractions—those with a particle size greater than 40 mm, those with a particle size between 10 mm and 40 mm, and those with a particle size less than 10 mm—was weighed and recorded to an accuracy of 0.1 kg. The crushing strength M40 is expressed as the percentage of coke particles larger than 40mm after drum rotation to the total mass of coke entering the drum; the abrasion resistance strength M10 is expressed as the percentage of coke particles smaller than 10mm after drum rotation to the total mass of coke entering the drum. Each sample is tested twice in parallel, and the final result is the arithmetic mean of the two measurements.

[0051] The hot-state properties of coke were tested using a coke reactivity and post-reaction strength measuring device. Dry coke lumps with a particle size of 21 mm to 25 mm were sieved from the sample, and 200.0 g were weighed and loaded into a quartz reactor. The reactor was placed in a vertical electric furnace preheated to 400℃, and heated to 1100℃ at a heating rate of 20℃ / min under the protection of high-purity nitrogen at a flow rate of 5.0 L / min, and held at that temperature. After the temperature stabilized, the gas was switched to high-purity carbon dioxide at a flow rate of 5.0 L / min, and the reaction was started and continued for 120 min. After the reaction was completed, the gas was switched back to nitrogen and heating was stopped. After cooling to room temperature, all the coke was removed, and its total mass was recorded as the mass of the post-reaction coke. Subsequently, all the post-reaction coke was loaded into a type I rotary drum and rotated at a speed of 20 r / min for 600 revolutions (30 min in total). After rotation, the coke was sieved using a 10.0 mm aperture sieve, and the mass of the material remaining on the sieve was accurately weighed. Coke reactivity (CRI) is calculated as the percentage of coke mass loss after reaction relative to the mass of coke before reaction; post-reaction strength (CSR) is calculated as the percentage of coke mass with a particle size greater than 10 mm after the drum reaction relative to the mass of coke before reaction.

[0052] The total sulfur content (St,d) of coke was determined by coulometric titration. The coke sample was ground in a mortar until it passed through a 0.2 mm standard sieve. Approximately 50.0 mg (accurate to 0.01 mg) of dried coke powder was weighed and evenly spread in a ceramic boat. The boat was placed into the inlet of the high-temperature furnace quartz tube of the tubular sulfur analyzer and burned at 1150 °C in a dry air stream at a flow rate of 1.5 L / min. The sulfur dioxide gas generated during combustion entered the electrolytic cell with the air stream, was absorbed, and reacted. The instrument automatically calculated and displayed the total sulfur mass percentage content in the sample according to Faraday's law based on the amount of electricity consumed during electrolysis. Each sample was measured three times, and the arithmetic mean of the three measurements was taken as the final reported value.

[0053] The performance test data above are shown in Table 1.

[0054] Table 1 Performance Test Results

[0055] As can be seen from the above, Examples 1 to 3 comprehensively and synergistically solve the three core technical problems pointed out in the background art.

[0056] Firstly, regarding the issue of "high-cost reliance on high-priced coking coal," Examples 1-3, while significantly increasing the proportion of low-priced, weakly caking coal and reducing the amount of high-priced coking coal in the coal blending, achieved a coke crushing strength (M40) of 89.8-91.5%, significantly higher than the 86.0% of Comparative Example 1 without any modifiers. This demonstrates that the present invention, by adding a very small amount (0.2-0.5%) of a specialized composite, effectively compensates for and surpasses the strength loss caused by reducing high-priced coal, achieving the cost control objective of replacing "high-priced coal" with "low-priced coal + high-efficiency additives."

[0057] Secondly, regarding the issue of excessive sulfur content, the total sulfur content of the coke obtained in the examples remained stable at 0.72-0.81%, all below the common limit of 0.85%, while the sulfur content of Comparative Example 1 was 0.98%. Crucially, the sulfur content of Comparative Example 3 (lacking magnesium-lithium composite oxides) was as high as 0.96%, almost identical to Comparative Example 1, while the sulfur content of Example 1 was as low as 0.72%. This directly and strongly confirms that the active metal oxide components loaded in the composite play a decisive role in chemical sulfur fixation, thereby allowing the safe use of some high-sulfur coking coal in coal blending to utilize its caking properties, thus solving the sulfur control problem at its source.

[0058] Finally, in addressing the issue of the "strength-cost imbalance," the embodiments not only improved cold-state strength but also achieved breakthroughs in key hot-state performance. The post-reaction strength CSR of Examples 1-3 reached 66.9-69.5%, an increase of 6.8-9.4 percentage points compared to 60.1% in Comparative Example 1; simultaneously, the coke reactivity CRI decreased by 5.8-7.7 percentage points. This indicates that the present invention optimizes the microstructure of coke, making it more resistant to erosion in the blast furnace. The CSR of Comparative Example 2 (lacking plasma treatment) was 64.3%, lower than 69.5% in Example 1, demonstrating that surface functionalization is crucial for ensuring uniform dispersion of the composite and strong bonding with the coal matrix, and is a necessary step to achieve synergistic strength improvement.

[0059] In summary, the test data clearly demonstrates that this invention, through the multi-synergistic mechanism of "physical enhancement - chemical sulfur fixation - catalytic optimization" of the composite, simultaneously achieves three major objectives: reducing coal blending costs, increasing coke strength (especially hot strength), and effectively controlling sulfur content. This successfully breaks the dilemma in traditional coking technology where cost, quality, and environmental protection are difficult to balance.

Claims

1. A method for blending coking coal, characterized in that, Includes the following steps: S1. By weight, 3-8 parts of high-sulfur fat coal, 12-16 parts of coking coal, 28-35 parts of weakly caking coal, 8-12 parts of gas-rich fat coal, 15-18 parts of gas coal, 0-20 parts of lean coking coal, and 0-25 parts of lean coal are fed into a crusher to be crushed to obtain blended coal. S2. The plasma-functionalized multi-level porous zeolite-carbon nanotube core-shell structure composite is premixed with 5-10% of the blended coal in step S1 in a mixer to obtain the masterbatch. S3. Mix the masterbatch with 90-95% of the blended coal by mass as described in step S1 in a mixer to obtain modified blended coal; S4. The modified blended coal is loaded into the coke oven and heated for carbonization.

2. The coking coal blending method according to claim 1, characterized in that, In step S1, the proportion of particles with a diameter of <3mm in the blended coal is 78-82%.

3. The coking coal blending method according to claim 1, characterized in that, In step S2, the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell structure composite accounts for 0.1-0.5% of the total mass of the blended coal.

4. The coking coal blending method according to claim 1, characterized in that, In step S3, the mixing time is 8-15 minutes.

5. The coking coal blending method according to claim 1, characterized in that, In step S4, the coke cake center temperature during the carbonization process is 1000-1050℃, and the coking time is 16-20h.

6. The coking coal blending method according to any one of claims 1-5, characterized in that, The preparation steps of the plasma-functionalized hierarchical porous zeolite-carbon nanotube core-shell structure composite include: A1. By weight, 18-22 parts of NaY zeolite are dispersed in 180-220 parts of a mixed aqueous solution of lanthanum nitrate and calcium nitrate, and stirred at 78-82℃ to obtain a mixture; the mixture is centrifuged to obtain a solid, and the solid is washed with deionized water to obtain a washed wet filter cake; the washed wet filter cake is redispersed in 180-220 parts of deionized water, and 1.4-1.6 parts of citric acid are added, and crystallization is carried out in a high-pressure reactor at 145-155℃; after natural cooling, the solid is collected by centrifugation, and the solid is washed with deionized water and calcined in a muffle furnace at 545-555℃ under an air atmosphere to obtain multi-level porous zeolite; A2. The multi-level porous zeolite was immersed in a nickel nitrate ethanol solution, dried, and then reduced in a hydrogen atmosphere at 395-405℃. It was then transferred to a CVD furnace and heated to 645-655℃ under argon protection. A mixture of ethylene, hydrogen, and argon was introduced to react the mixture, and the mixture was cooled to obtain a zeolite-carbon nanotube core-shell intermediate. A3. The zeolite-carbon nanotube core-shell intermediate was placed in a plasma treatment instrument, vacuumed, oxygen was introduced, and plasma treatment was performed; vacuum cooling was then performed to obtain a functional material with oxygen-containing functional groups on the surface. A4. Dissolve magnesium nitrate hexahydrate and lithium nitrate trihydrate in deionized water to obtain an impregnation solution; place the functional material with oxygen-containing functional groups on the surface in the impregnation solution, disperse it ultrasonically at 24-26℃, and let it stand for impregnation; after impregnation, filter to obtain a solid, place the solid in a forced-air drying oven, dry it at 58-62℃ to obtain a dried precursor powder, place the dried precursor powder in a muffle furnace, heat it to 490-510℃, calcine it in an air atmosphere, cool it, grind and sieve it.

7. The coking coal blending method according to claim 6, characterized in that, In step A1, the calcination time in air atmosphere is 4-6 hours.

8. The coking coal blending method according to claim 6, characterized in that, In step A2, the reduction time under a hydrogen atmosphere at 395-405℃ is 2-4 hours.

9. The coking coal blending method according to claim 6, characterized in that, In step A3, the plasma treatment time is 15-30 minutes.

10. The coking coal blending method according to claim 6, characterized in that, In step A4, the calcination time in air atmosphere is 4-6 hours.

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