Method for preparing high-strength metallurgical coke based on inferior coal regeneration

Abstract

The invention discloses a method for preparing high-strength metallurgical coke based on inferior coal regeneration, belongs to the technical field of metallurgical coke preparation, and is used for solving the technical problem that in the prior art, inferior coal is difficult to stably regenerate to prepare high-strength metallurgical coke. According to the preparation method of the metallurgical coke, the modified phenolic resin and the epoxy modified polyurethane are prepared, cross-linking is carried out among inferior coal particles to form a net, interface bonding is improved, then the density is improved through briquetting, communication holes and cracks are reduced, and the metallurgical coke is obtained. Segmental heating is used for inhibiting severe volatilization precipitation and shrinkage cracking, the completeness of a coke skeleton is remarkably improved, the crushing strength and the strength after reaction are improved, the reactivity is reduced, and the high-strength metallurgical coke is prepared through regeneration of low-quality coal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical coke preparation, and particularly relates to a method for preparing high-strength metallurgical coke based on regenerated inferior coal. BACKGROUND

[0002] In recent years, the research and engineering path of preparing metallurgical coke from regenerated inferior coal has generally evolved from simply blending to reduce costs to structural regulation and quality improvement. In the early stage, the proportion of high-quality coking coal was increased and the proportion of inferior coal was reduced to ensure the strength and thermal indicators of coke. Subsequently, schemes were gradually developed to increase the proportion of inferior coal by forming, pretreatment and process intensification, so that the coke obtained is closer to the requirements of blast furnace coke in terms of cold strength, block size retention and thermal post-reaction strength. At the same time, industry evaluation has also expanded from only focusing on ash content, sulfur content and yield to comprehensive balance of crushing strength, reactivity, post-reaction strength, and the impact on in-furnace pulverization and permeability, promoting the continuous iteration of the technical route of high-proportion inferior coal resource utilization and metallurgical performance compliance.

[0003] Currently, on the raw material side, common practices include blending with strong-bonding primary coking coal / fat coal, adding coke powder or semicoke to improve the skeleton, using coking byproducts as a bonding phase, or introducing inorganic bonding / skeleton materials to improve the forming stability. On the process side, common methods include coal preheating and moisture adjustment, increasing the charging density, optimizing the particle size distribution and mixing uniformity, ash reduction by washing and selecting the coal, mild oxidation or solvent extraction to regulate the plastic zone behavior, and reactivity regulation by adding a small amount of mineral salts / metal oxides, etc., in order to improve the metallurgical coke indicators without changing the main coking process.

[0004] However, in the above methods, blending relies on high-quality coking coal resources, which has large cost and supply fluctuations and a clear upper limit to quality for quantity, coal pitch / tar-based binders can improve forming and bonding, but have strong volatilization and cracking during carbonization, leading to high reactivity and limited post-reaction strength improvement, and may also cause sulfur and impurity migration and emission control pressure. Inorganic bonding / fillers often increase ash content, change ash fusion and slag phase behavior, and have poor interface matching with carbon, easily forming hard point-weak interface structure, with limited cold crushing strength improvement and insufficient hot anti-pulverization. Simply increasing the charging density or pretreatment can partially improve the structural density, but weakly bonded coal lacks continuous carbon skeleton and interface bonding.

[0005] In view of the technical defects in this regard, a solution is proposed. SUMMARY

[0006] The present application aims to provide a method for preparing high-strength metallurgical coke based on regenerated inferior coal, to solve the technical problem that it is difficult to stably regenerate high-strength metallurgical coke from inferior coal in the prior art.

[0007] The object of the present application can be achieved by the following technical solution: a method for preparing high-strength metallurgical coke based on inferior coal regeneration, comprising the following steps: S1, placing inferior coal in a high-speed homogenizer for stirring, spraying a modified dispersion liquid, high-speed stirring for 15-30 min, high-temperature pretreatment, to obtain resin cross-linked reinforced coal material; The preparation reaction principle of the resin cross-linked reinforced coal material is: During the reaction process, the modified dispersion liquid is uniformly sprayed and distributed on the surface and pores of the inferior coal particles through high-speed homogenizing stirring, the resin molecules fully wet the coal surface and penetrate into the microporous structure under high shear, and then the solvent in the dispersion liquid is removed through high-temperature pretreatment, at the same time, the modified phenolic resin and the epoxy modified polyurethane further occur pre-curing reaction, forming a three-dimensional cross-linked network mainly composed of covalent bonds and physical association between coal particles and on the surface of coal particles, to obtain the resin cross-linked reinforced coal material; S2, sending the resin cross-linked reinforced coal material into a briquetting machine for compression molding, to obtain reinforced coal briquettes; The preparation reaction principle of the reinforced coal briquettes is: During the reaction process, the resin cross-linked reinforced coal material in the pre-curing state occurs particle rearrangement and densification under the action of external pressure, and the resin network fills the inter-particle gaps and forms a continuous bonding phase under the action of pressure, to obtain the structure-stable reinforced coal briquettes.

[0008] S3, placing the reinforced coal briquettes in a tube furnace protected by a nitrogen atmosphere, heating to 400-500℃ at a heating rate of 2-4℃ / min, and keeping the temperature for 0.5-1h, to obtain pre-carbonized coal briquettes; The preparation reaction principle of the pre-carbonized coal briquettes is: During the reaction process, pyrolysis and preliminary carbonization reactions occur in the coal and resin system, the organic structure in the resin gradually breaks and is converted into a carbon-rich structure, the volatile matter in the coal is released, and a continuous semicoke / carbon skeleton is formed, so that the briquettes are converted into pre-carbonized coal briquettes with certain mechanical integrity.

[0009] S4, placing the pre-carbonized coal briquettes in a carbonization furnace protected by a nitrogen atmosphere, heating to 900-1000℃ at a heating rate of 8-10℃ / min, keeping the temperature for 2-4h, and cooling to obtain metallurgical coke.

[0010] The preparation reaction principle of the metallurgical coke is: During the reaction process, under the further high-temperature inert atmosphere, the organic residues and semicoke structures in the pre-carbonized coal briquettes occur deep pyrolysis, condensation and aromatization reactions, gradually forming a stable carbon structure mainly composed of polycyclic aromatic carbon layers, and the pore structure and carbon skeleton are continuously developed and rearranged, to finally generate finished metallurgical coke with typical carbon structure characteristics of metallurgical coke.

[0011] Further, in step S1, the ratio of the amount of the low-quality coal and the modified dispersion liquid is 90-100 g:25-35 mL, the modified dispersion liquid is obtained by uniformly mixing modified phenolic aldehyde resin, epoxy modified polyurethane, deionized water and ethanol according to the ratio of 10-15 g:4-6 g:2-4 mL:8-10 mL, the low-quality coal is 1-3 mm fine-grained weakly caking coal, the caking index is 0-30, and the volatile matter is 20-45 wt%; Further, the preparation method of the resin cross-linked reinforced coal material is as follows: the low-quality coal is placed in a high-speed homogenizer for stirring, and the modified dispersion liquid is sprayed, then the mixture is stirred at a high speed of 1500-2000 rpm for 15-30 min, then the mixture is transferred to a vacuum drying box with a temperature of 60-80 ℃ for heat preservation treatment for 0.5-1 h, and then the temperature of the vacuum drying box is increased to 90-100 ℃ for heat preservation treatment for 0.5-1 h, thereby obtaining the resin cross-linked reinforced coal material. Further, in step S2, the pressure of the briquetting machine is set to 30-40 MPa, the size of the reinforced coal briquette is 25×25×25 mm, and the briquette density is 1.10-1.25 g·cm -3 ; Further, the modified phenolic aldehyde resin is prepared by the following steps: A1, phenol, ammonia solution and formaldehyde solution are placed in a reaction kettle for stirring, the reaction kettle is heated to 65-75 ℃, and heat preservation reaction is performed for 1-2 h, and then the phenolic aldehyde resin prepolymer is obtained by post-treatment; A2, the phenolic aldehyde resin prepolymer, deionized water and boric acid are placed in a reaction kettle for stirring, acetic acid solution is added to adjust the pH to 4-5, the reaction kettle is heated to 85-95 ℃, heat preservation reaction is performed for 1-2 h, methyl trimethoxysilane is added, heat preservation reaction is performed for 1-2 h, and then the modified phenolic aldehyde resin is obtained by post-treatment.

[0012] The preparation reaction formula of the modified phenolic aldehyde resin is as follows:

[0013] The preparation reaction principle of the modified phenolic aldehyde resin is as follows: In the reaction process, the phenol is activated in an alkaline environment, the formaldehyde reacts with the aromatic ring in the form of an electrophile to generate hydroxymethyl phenol by preferentially introducing hydroxymethyl groups at the ortho / para position, the hydroxymethyl groups and other phenolic rings further react to form methylene bridge or methylene ether bridge connection structures, and the phenolic aldehyde resin prepolymer containing hydroxymethyl and phenolic hydroxyl groups is obtained, in step A2, the hydroxymethyl groups of the prepolymer form borate ester connection under acidic conditions, the system is introduced into the cross-linking structure containing boron, then methyl trimethoxysilane is added, the silicon-oxygen bond is first hydrolyzed to generate silanol under the action of acid catalysis and water, and then the silanol and the hydroxyl groups on the resin molecules react to generate Si-O-C bond, and finally the modified phenolic aldehyde resin containing boron and silicon structure units is obtained.

[0014] Further, in step A1, the amount ratio of the phenol, ammonia solution and formaldehyde solution is 8-10 g: 1-2 mL: 13-15 g, the concentration of the ammonia solution is 20-25 wt%, and the concentration of the formaldehyde solution is 35-37 wt%, and the post-treatment step comprises: after the reaction is completed, the reaction system is heated to 80-90°C, and deionized water is removed by distillation under reduced pressure to obtain a phenolic aldehyde resin prepolymer; Further, in step A2, the amount ratio of the phenolic aldehyde resin prepolymer, deionized water, boric acid and methyl trimethoxysilane is 10-15 g: 10-15 mL: 1-3 g: 6-8 g, and the concentration of the acetic acid solution is 3-5 wt%, and the post-treatment step comprises: after the reaction is completed, the reaction liquid is preserved and distilled under reduced pressure to remove low-boiling substances to obtain a modified phenolic aldehyde resin.

[0015] Further, the epoxy-modified polyurethane is prepared by the following steps: B1, polyethylene glycol, 2, 2-bis (4'-hydroxyphenyl) propane and dibutyltin dilaurate are stirred in a reaction kettle protected by a nitrogen atmosphere, 4, 4'-methylene bis (phenyl isocyanate) is added, the reaction kettle is heated to 70-75°C, and the reaction is preserved for 1-2 h to obtain a polyurethane prepolymer solution; B2, the polyurethane prepolymer solution and dibutyltin dilaurate are stirred in a reaction kettle protected by a nitrogen atmosphere, and epoxy resin E-51 is added, the reaction kettle is heated to 75-85°C, and the reaction is preserved for 1-2 h to obtain an epoxy-modified polyurethane after post-treatment.

[0016] The preparation reaction principle of the epoxy-modified polyurethane is: During the reaction, polyethylene glycol and 2, 2-bis (4'-hydroxyphenyl) propane are used as a hydroxyl-containing polyol component, and addition reaction occurs with 4, 4'-methylene bis (phenyl isocyanate) under the catalysis of dibutyltin dilaurate, the excess of 4, 4'-methylene bis (phenyl isocyanate) is controlled to obtain a polyurethane prepolymer with isocyanate groups at the end, and in step B2, the polyurethane prepolymer is mixed with epoxy resin E-51 and heated to react, the epoxy groups in the epoxy resin molecules undergo ring-opening reaction with the isocyanate groups under the conditions of heat and catalysis, the excess of epoxy resin E-51 is controlled to make the two kinds of polymers combine through covalent bonds to obtain an epoxy-modified polyurethane system terminated by epoxy groups.

[0017] Further, in step B1, the weight ratio of the polyethylene glycol, 2, 2-bis (4'-hydroxyphenyl) propane and dibutyltin dilaurate is 10-15: 1-3: 0.003-0.005, and the molar amount of 4, 4'-methylene bis (phenyl isocyanate) is 0.55 times the total molar amount of the hydroxyl groups of the polyethylene glycol and 2, 2-bis (4'-hydroxyphenyl) propane. Further, in step B2, the weight ratio of the polyurethane prepolymer solution and dibutyltin dilaurate is 20-25:0.002-0.004, the molar amount of the epoxy resin E-51 is 0.55 times the molar amount of the isocyanate group in the polyurethane prepolymer solution, and the post-treatment step comprises: after the reaction is completed, the reaction system is cooled to 50-60 DEG C, low-boiling substances are removed under reduced pressure, and the product is sealed and stored, to obtain the epoxy-modified polyurethane.

[0018] The present application has the following advantages: 1. The epoxy-modified polyurethane of the present application, in the resin crosslinking and coal reinforcement stage, has both flexible polyurethane segments and active epoxy groups in the molecule, can occur synergistic crosslinking with modified phenolic resin, and firmly adhere to the surface of low-quality coal particles through hydrogen bonding, polar interaction and chemical bonding, play the role of bridging-coating-filling, improve the overall cohesiveness and forming strength of the coal, so that the briquettes are not easy to crack or corner in the forming and handling process, secondly, in the subsequent pre-carbonization and high-temperature carbonization process, the epoxy-modified polyurethane and phenolic resin together occur pyrolysis and carbonization, can form a continuous and dense carbon skeleton structure, effectively make up for the poor plasticity and insufficient coking property of low-quality coal, inhibit crack propagation, improve the uniformity of pore structure, at the same time, the introduction of aromatic structure and epoxy crosslinking network in the epoxy-modified polyurethane is conducive to improving the integrity of the carbon skeleton after carbonization, so that the obtained metallurgical coke has higher crushing strength while maintaining reasonable porosity.

[0019] 2. The modified phenolic resin of the present application, in the resin crosslinking and coal reinforcement stage, has high polarity and good wettability, can uniformly disperse and coat on the surface of low-quality coal particles, significantly enhance the bonding strength between coal particles through physical adsorption and chemical crosslinking, effectively improve the poor cohesiveness and difficult forming of low-quality coal, so that the reinforced coal briquettes obtained by pressing have high forming strength and integrity, secondly, the crosslinking density and thermal stability of the phenolic resin modified by boric acid and silane coupling agent are significantly improved, which can gradually transform into stable aromatic carbon structure during pre-carbonization and high-temperature carbonization, forming a continuous and dense carbon network, which plays a role of skeleton support and structure filling for coal particles, which not only helps to inhibit crack propagation due to volatilization during carbonization, but also optimizes the pore structure of coke, making the pore distribution more uniform and reasonable, further, the high-strength carbon skeleton formed after carbonization of the modified phenolic resin can significantly improve the crushing strength and wear resistance of metallurgical coke, and at the same time, enhance the structural stability of the coke in high-temperature carbon dioxide atmosphere, thereby being conducive to improving the strength after reaction.

[0020] 3、The application adopts nitrogen protection environment throughout the resin synthesis, pre-carbonization and high-temperature carbonization process, effectively avoids the damage of oxidation reaction to the resin structure and coal material, ensures the complete formation of carbon skeleton in the carbonization process, secondly, in the resin crosslinking and strengthening coal material preparation stage, the resin system is uniformly covered on the surface of coal particles through high-speed homogeneous dispersion and spraying mode, which is beneficial to form a continuous bonding network, reduces local resin enrichment or loss, thereby improving the uniformity of the briquette structure, at the same time, the staged vacuum drying and pre-carbonization treatment can slowly and fully remove the solvent and low molecular volatile matter, reduces the internal stress and crack risk caused by gas concentration during subsequent high-temperature carbonization, further, the slow heating rate in the pre-carbonization stage is helpful to the collaborative carbonization of resin and coal, and preliminarily establishes a stable carbon skeleton, providing a structural basis for high-temperature carbonization, and the regular geometric shape of the briquette obtained through briquetting can effectively control the particle size and bulk density distribution of the metallurgical coke, and reduce the coke fines generation. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0022] The polyethylene glycol used in the present application is purchased from Jiangsu Haian Petroleum Chemical Plant, the model is PEG-2000, and the brand is Haishihua; The epoxy resin E-51 used in the present application is purchased from Hebei Gujia Technology Co., Ltd., the grade is E-51, and the brand is Phoenix.

[0023] Embodiment 1: The present embodiment provides a method for modifying polyurethane with epoxy, comprising the following steps: Step I, preparation of polyurethane prepolymer solution Weigh: polyethylene glycol 100g, 2,2-bis(4'-hydroxyphenyl)propane 10g and dibutyltin dilaurate 0.03g are placed in a reaction kettle protected by nitrogen atmosphere and stirred, 4,4'-methylenebis(isocyanate phenyl ester) is added according to 0.55 times of the total hydroxyl molar amount of polyethylene glycol and 2,2-bis(4'-hydroxyphenyl)propane, the reaction kettle is heated to 70℃, and the reaction is kept for 1h to obtain a polyurethane prepolymer solution.

[0024] Step II, preparation of epoxy modified polyurethane Weigh 200g of polyurethane prepolymer and 0.02g of dibutyltin dilaurate and place them in a nitrogen-protected reactor and stir. Add epoxy resin E-51 at 0.55 times the molar amount of isocyanate groups in the polyurethane prepolymer. Heat the reactor to 75℃ and react for 1 hour. After the reaction is complete, wait for the reaction system to cool to 50℃, remove low-boiling substances under reduced pressure, seal and store to obtain epoxy-modified polyurethane.

[0025] Example 2: This example provides a method for epoxy-modified polyurethane, including the following steps: Step I: Preparation of polyurethane prepolymer solution Weigh out 125g of polyethylene glycol, 20g of 2,2-bis(4′-hydroxyphenyl)propane and 0.04g of dibutyltin dilaurate and place them in a nitrogen-protected reactor and stir. Add 4,4'-methylenebis(phenyl isocyanate) at 0.55 times the total molar amount of hydroxyl groups in polyethylene glycol and 2,2-bis(4′-hydroxyphenyl)propane. Heat the reactor to 72°C and maintain the temperature for 1.5h to obtain a polyurethane prepolymer.

[0026] Step II: Preparation of epoxy-modified polyurethane Weigh 225g of polyurethane prepolymer and 0.03g of dibutyltin dilaurate and place them in a nitrogen-protected reactor and stir. Add epoxy resin E-51 at 0.55 times the molar amount of isocyanate groups in the polyurethane prepolymer. Heat the reactor to 80℃ and react for 1.5h. After the reaction is complete, wait for the reaction system to cool to 55℃, remove low-boiling substances under reduced pressure, seal and store to obtain epoxy-modified polyurethane.

[0027] Example 3: This example provides a method for epoxy-modified polyurethane, including the following steps: Step I: Preparation of polyurethane prepolymer solution Weigh out 150g of polyethylene glycol, 30g of 2,2-bis(4′-hydroxyphenyl)propane and 0.05g of dibutyltin dilaurate and place them in a nitrogen-protected reactor and stir. Add 4,4'-methylenebis(phenyl isocyanate) at 0.55 times the total molar amount of hydroxyl groups in polyethylene glycol and 2,2-bis(4′-hydroxyphenyl)propane. Heat the reactor to 75°C and maintain the temperature for 2 hours to obtain a polyurethane prepolymer.

[0028] Step II: Preparation of epoxy-modified polyurethane Weigh 250g of polyurethane prepolymer and 0.04g of dibutyltin dilaurate and place them in a nitrogen-protected reactor and stir. Add epoxy resin E-51 at 0.55 times the molar amount of isocyanate groups in the polyurethane prepolymer. Heat the reactor to 85℃ and react for 2 hours. After the reaction is complete, wait for the reaction system to cool to 60℃, remove low-boiling substances under reduced pressure, seal and store to obtain epoxy-modified polyurethane.

[0029] Embodiment 4: The embodiment provides a method for modifying a phenolic resin, comprising the following steps: Step 1, preparing a phenolic resin prepolymer Take 80 g of phenol, 10 mL of 20 wt% ammonia water solution and 130 g of 35 wt% formaldehyde solution, and stir them in a reaction kettle. Heat the reaction kettle to 65°C, and keep the temperature for 1 h. After the reaction is completed, heat the reaction system to 80°C, and remove the deionized water by distillation under reduced pressure to obtain a phenolic resin prepolymer.

[0030] Step 2, preparing a modified phenolic resin Take 100 g of the phenolic resin prepolymer, 100 mL of deionized water and 10 g of boric acid, and stir them in a reaction kettle. Add 3 wt% acetic acid solution to adjust the pH to 4. Heat the reaction kettle to 85°C, and keep the temperature for 1 h. Then add 60 g of methyltrimethoxysilane, and keep the temperature for 1 h. After the reaction is completed, remove the low-boiling substances by distillation under reduced pressure to obtain a modified phenolic resin.

[0031] Embodiment 5: The embodiment provides a method for modifying a phenolic resin, comprising the following steps: Step 1, preparing a phenolic resin prepolymer Take 90 g of phenol, 15 mL of 22.5 wt% ammonia water solution and 140 g of 36 wt% formaldehyde solution, and stir them in a reaction kettle. Heat the reaction kettle to 70°C, and keep the temperature for 1.5 h. After the reaction is completed, heat the reaction system to 85°C, and remove the deionized water by distillation under reduced pressure to obtain a phenolic resin prepolymer.

[0032] Step 2, preparing a modified phenolic resin Take 125 g of the phenolic resin prepolymer, 125 mL of deionized water and 20 g of boric acid, and stir them in a reaction kettle. Add 4 wt% acetic acid solution to adjust the pH to 4.5. Heat the reaction kettle to 90°C, and keep the temperature for 1.5 h. Then add 70 g of methyltrimethoxysilane, and keep the temperature for 1.5 h. After the reaction is completed, remove the low-boiling substances by distillation under reduced pressure to obtain a modified phenolic resin.

[0033] Embodiment 6: The embodiment provides a method for modifying a phenolic resin, comprising the following steps: Step 1, preparing a phenolic resin prepolymer Take 100 g of phenol, 20 mL of 25 wt% ammonia water solution and 150 g of 37 wt% formaldehyde solution, and stir them in a reaction kettle. Heat the reaction kettle to 75°C, and keep the temperature for 2 h. After the reaction is completed, heat the reaction system to 90°C, and remove the deionized water by distillation under reduced pressure to obtain a phenolic resin prepolymer.

[0034] Step 2, preparing a modified phenolic resin Take: phenolic resin prepolymer 150 g, deionized water 150 mL and boric acid 30 g in the reaction kettle stirring, adding 5 wt% acetic acid solution to adjust pH to 5, the reaction kettle to 95 ℃, keep the reaction for 2 h, add methyl trimethoxysilane 80 g, keep the reaction for 2 h, after the reaction is completed, the reaction liquid is kept and distilled under reduced pressure, the low boiling point is removed, and the modified phenolic resin is obtained.

[0035] Example 7: The present embodiment provides a method for preparing high-strength metallurgical coke based on low-quality coal regeneration, comprising the following steps: Step one, preparation of resin crosslinking reinforced coal material Take: modified phenolic resin 100 g, epoxy modified polyurethane 40 g, deionized water 20 mL and ethanol 80 mL are mixed uniformly to obtain a modified dispersion liquid, which is prepared for use; Take: 900 g of low-quality coal is placed in a high-speed homogenizer and stirred, and 250 mL of modified dispersion liquid is sprayed. After high-speed stirring at 1500 rpm for 15 min, the mixture is transferred to a vacuum drying oven with a temperature of 60 ℃, and kept for 0.5 h. The vacuum drying oven is heated to 90 ℃, and kept for 0.5 h. The resin crosslinking reinforced coal material is obtained.

[0036] Step two, preparation of reinforced coal briquettes The resin crosslinking reinforced coal material is sent into the briquetting machine and pressed into shape to obtain the reinforced coal briquettes.

[0037] Step three, preparation of pre-carbonized coal briquettes The reinforced coal briquettes are placed in a tubular furnace protected by a nitrogen atmosphere and heated to 400 ℃ at a heating rate of 2 ℃ / min, and kept for 0.5 h to obtain the pre-carbonized coal briquettes.

[0038] Step four, preparation of metallurgical coke The pre-carbonized coal briquettes are placed in a carbonization furnace protected by a nitrogen atmosphere and heated to 900 ℃ at a heating rate of 8 ℃ / min, and kept for 2 h to obtain the metallurgical coke.

[0039] Example 8: The present embodiment provides a method for preparing high-strength metallurgical coke based on low-quality coal regeneration, comprising the following steps: Step one, preparation of resin crosslinking reinforced coal material Take: modified phenolic resin 125 g, epoxy modified polyurethane 50 g, deionized water 304 mL and ethanol 90 mL are mixed uniformly to obtain a modified dispersion liquid, which is prepared for use; Take: 950 g of low-quality coal is placed in a high-speed homogenizer and stirred, and 300 mL of modified dispersion liquid is sprayed. After high-speed stirring at 1750 rpm for 22 min, the mixture is transferred to a vacuum drying oven with a temperature of 70 ℃, and kept for 1 h. The vacuum drying oven is heated to 95 ℃, and kept for 1 h. The resin crosslinking reinforced coal material is obtained.

[0040] Step two, preparation of enhanced coal briquette The resin cross-linked enhanced coal material is sent into a briquetting machine for compression molding to obtain an enhanced coal briquette.

[0041] Step three, preparation of pre-carbonized coal briquette The enhanced coal briquette is placed in a tube furnace under nitrogen atmosphere protection and heated to 450℃ at a heating rate of 3℃ / min, and kept for 1h to obtain a pre-carbonized coal briquette.

[0042] Step four, preparation of metallurgical coke The pre-carbonized coal briquette is placed in a carbonization furnace under nitrogen atmosphere protection and heated to 950℃ at a heating rate of 9℃ / min, and kept for 3h to obtain a metallurgical coke.

[0043] Example 9: This example provides a method for preparing high-strength metallurgical coke based on low-quality coal regeneration, comprising the following steps: Step one, preparation of resin cross-linked enhanced coal material Take: 150g of modified phenolic resin, 60g of epoxy modified polyurethane, 40mL of deionized water and 100mL of ethanol are mixed uniformly to obtain a modified dispersion liquid, which is ready for use; Take: 1000g of low-quality coal is placed in a high-speed homogenizer and stirred, and 350mL of modified dispersion liquid is sprayed. After high-speed stirring at 2000rpm for 30min, the mixture is transferred to a vacuum drying box with a temperature of 80℃, and kept for 1h. The vacuum drying box is heated to 100℃, and kept for 1h to obtain a resin cross-linked enhanced coal material.

[0044] Step two, preparation of enhanced coal briquette The resin cross-linked enhanced coal material is sent into a briquetting machine for compression molding to obtain an enhanced coal briquette.

[0045] Step three, preparation of pre-carbonized coal briquette The enhanced coal briquette is placed in a tube furnace under nitrogen atmosphere protection and heated to 500℃ at a heating rate of 4℃ / min, and kept for 1h to obtain a pre-carbonized coal briquette.

[0046] Step four, preparation of metallurgical coke The pre-carbonized coal briquette is placed in a carbonization furnace under nitrogen atmosphere protection and heated to 1000℃ at a heating rate of 10℃ / min, and kept for 4h to obtain a metallurgical coke.

[0047] Comparative Example 1: The difference between this comparative example and Example 9 is that in Step one of preparing the resin cross-linked enhanced coal material, the epoxy modified polyurethane is not used.

[0048] Comparative Example 2: The difference between this comparative example and Example 9 is that in Step one of preparing the resin cross-linked enhanced coal material, the modified phenolic resin is not used.

[0049] Performance test: The ash content, sulfur content, crushing strength (M25), reactivity and post-reaction strength of the metallurgical coke prepared from Example 7-9 and Comparative Example 1-2 were determined according to the standard GB / T 1996-2017 "Metallurgical Coke", and the specific data are shown in Table 1.

[0050] Table 1 - Performance test data table of each sample

[0051] Data analysis: According to the comparative analysis of Table 1, the ash content of the metallurgical coke prepared by the present application is 11.3%, the sulfur content is 0.69%, the crushing strength is 93.7%, the reactivity is 27.5%, and the post-reaction strength is 62.3%. Comparative analysis of the data of Example 9 and Comparative Example 1 shows that the ash content, sulfur content and reactivity of the metallurgical coke prepared by Comparative Example 1 all increase, and the crushing strength and post-reaction strength all decrease, indicating that the epoxy modified polyurethane prepared by the present application can toughen, buffer stress, improve wet dispersion and interfacial adhesion in the system. After the use is cancelled, the resin crosslinking enhances the coal material to be more prone to stress concentration due to volume shrinkage and volatile release during the drying-precarbonization-carbonization process, resulting in an increase in microcracks and connected pores, and the continuity and integrity of the coke skeleton formed after carbonization are poor, thus the crushing strength decreases, the reactivity increases and the post-reaction strength decreases, and the ash content and sulfur content are slightly weakened. Comparative analysis of the data of Example 9 and Comparative Example 2 shows that the ash content, sulfur content and reactivity of the metallurgical coke prepared by Comparative Example 2 all increase, and the crushing strength and post-reaction strength all significantly decrease, indicating that after the use of the modified phenolic resin prepared by the present application is cancelled, the system loses the main source of forming a continuous and dense carbon skeleton, the remaining polyurethane component has a relatively low carbonization rate and a stronger volatile release, and more pores and structural defects are more likely to be formed during carbonization, resulting in a more loose coke overall and a decrease in the load-bearing capacity of the skeleton, thus the crushing strength decreases significantly, the reactivity increases significantly, and the post-reaction strength decreases significantly. At the same time, due to the decrease in the contribution of the effective carbon skeleton and the decrease in the coke yield, the proportion of the mineral matter in the raw coal in the finished product increases relatively, and the ash content increases significantly, and the sulfur content also increases due to the dilution effect.

[0052] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details and limit the present application to the specific embodiments. Obviously, many modifications and changes can be made according to the content of the present application. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited by the claims and their entire scope and equivalents.

Claims

1. A method for producing high strength metallurgical coke based on the regeneration of low grade coal, characterized by, The method comprises the following steps: S1, placing the low-quality coal in a high-speed homogenizer, spraying a modified dispersion liquid, high-speed stirring for 15-30 min, high-temperature pretreatment, and obtaining resin cross-linked reinforced coal material; S2, feeding the resin cross-linked reinforced coal material into a briquetting machine, and pressing and forming to obtain reinforced coal briquettes; S3, placing the reinforced coal briquettes in a tube furnace protected by a nitrogen atmosphere, heating to 400-500 DEG C at a heating rate of 2-4 DEG C / min, and keeping the temperature for 0.5-1 h to obtain pre-carbonized coal briquettes; S4, placing the pre-carbonized coal briquettes in a carbonization furnace protected by a nitrogen atmosphere, heating to 900-1000 DEG C at a heating rate of 8-10 DEG C / min, keeping the temperature for 2-4 h, and cooling to obtain metallurgical coke.

2. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 1 wherein, In step S1, the amount ratio of the low-quality coal to the modified dispersion liquid is 90-100 g:25-35 mL, the modified dispersion liquid is obtained by uniformly mixing modified phenolic resin, epoxy modified polyurethane, deionized water and ethanol according to the amount ratio of 10-15 g:4-6 g:2-4 mL:8-10 mL, the low-quality coal is 1-3 mm fine-grained weakly caking coal, the caking index is 0-30, and the volatile matter is 20-45 wt%.

3. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 1 wherein, In step S2, the pressure of the briquetting machine is set to 30-40 MPa, the size of the enhanced coal briquette is 25x25x25 mm, and the briquette density is 1.10-1.25 g-cm -3 .

4. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 2 wherein, The modified phenolic resin is prepared by the following steps: A1, placing phenol, ammonia solution and formaldehyde solution in a reaction kettle, stirring, heating the reaction kettle to 65-75 DEG C, keeping the temperature for 1-2 h, and post-treating to obtain phenolic resin prepolymer; A2, placing the phenolic resin prepolymer, deionized water and boric acid in a reaction kettle, stirring, adding acetic acid solution to adjust the pH to 4-5, heating the reaction kettle to 85-95 DEG C, keeping the temperature for 1-2 h, adding methyltrimethoxysilane, keeping the temperature for 1-2 h, and post-treating to obtain modified phenolic resin.

5. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 4 wherein, In step A1, the amount ratio of the phenol, ammonia solution and formaldehyde solution is 8-10 g:1-2 mL:13-15 g, the concentration of the ammonia solution is 20-25 wt%, and the concentration of the formaldehyde solution is 35-37 wt%; in step A2, the amount ratio of the phenolic resin prepolymer, deionized water, boric acid and methyltrimethoxysilane is 10-15 g:10-15 mL:1-3 g:6-8 g, and the concentration of the acetic acid solution is 3-5 wt%.

6. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 2 wherein, The epoxy modified polyurethane is prepared by the following steps: B1, placing polyethylene glycol, 2,2-bis(4'-hydroxyphenyl)propane and dibutyltin dilaurate in a reaction kettle protected by a nitrogen atmosphere, stirring, adding 4,4'-methylenebis(isocyanate), heating the reaction kettle to 70-75 DEG C, keeping the temperature for 1-2 h, and obtaining polyurethane prepolymer solution; B2, placing the polyurethane prepolymer solution and dibutyltin dilaurate in a reaction kettle protected by a nitrogen atmosphere, stirring, adding epoxy resin E-51, heating the reaction kettle to 75-85 DEG C, reacting for 1-2 h, and post-treating to obtain epoxy modified polyurethane.

7. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 6 wherein, In Step B1, the weight ratio of the polyethylene glycol, 2,2-bis(4'-hydroxyphenyl)propane and dibutyl tin dilaurate is 10-15:1-3:0.003-0.005, and the molar amount of 4,4'-methylenebis(phenyl isocyanate) is 0.55 times the total molar amount of the hydroxyl groups of the polyethylene glycol and 2,2-bis(4'-hydroxyphenyl)propane.

8. A process for producing high strength metallurgical coke based on sub- grade coal regeneration as claimed in claim 6 wherein, In Step B2, the weight ratio of the polyurethane prepolymer solution and dibutyl tin dilaurate is 20-25:0.002-0.004, and the molar amount of the epoxy resin E-51 is 0.55 times the molar amount of the isocyanate groups in the polyurethane prepolymer solution.

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