Method for coal blending and coking by using modified high-rank coal

Abstract

The invention discloses a method for coal blending and coking by using modified high-rank coal, and belongs to the technical field of coal blending and coking. According to the invention, the high-rank coal is firstly modified, the used modification method is simple to operate and low in cost, and the high-rank coal such as meager lean coal can be used as coke fat coal through modification; and the coal is matched with other coals, and high-quality coke is refined by changing the ratio of different coals, so that the coking coal resource is expanded. The coke produced by the method has the properties that the crushing strength M40 is more than or equal to 75%, the abrasive resistance M10 is less than or equal to 8.5%, the reactivity CRI is less than or equal to 35%, and the post-reaction strength CSR is more than or equal to 50%. According to the method, the utilization rate of coal resources is increased, on the premise that the coke quality is guaranteed, the modified high-rank coal partially replaces the coking fat coal, the coal blending cost is effectively reduced, a special coal blending coking method is formed based on the modified high-rank coal, high-quality coke is prepared by regulating and controlling the proportion, the granularity, the moisture and the like, the economic benefits of enterprises are increased, and the economic benefits of the enterprises are increased. The cost advantage of an enterprise in the market is enhanced, and green development of the enterprise is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for coking by using modified high-rank coal blending, and belongs to the technical field of coal blending for coking. BACKGROUND

[0002] Coking is an important basic link in the steel industry, and with the development of the steel industry, the demand for high-quality coking coal is increasing. Although China is rich in coal resources, the resources of coking coal are relatively scarce, especially the proportion of strong caking fat coal resources is less than 10%. At the same time, the reserves of lean coal, lean meagre coal and other high-rank coal are abundant, but due to the dense structure of the coal, it is almost impossible to generate colloid during pyrolysis, and the caking property is extremely low, so it is difficult to form dense coke by itself. Therefore, researchers develop high-rank pulverized coal modifier or binder and corresponding coal blending coking method to realize the efficient utilization of high-rank coal in coking, reduce the use of high-quality coking coal in China, and alleviate the shortage of high-quality coking coal resources.

[0003] Chinese patent CN103045280A discloses a method for coking by using modified anthracite coal powder and the modified anthracite coal powder. The components and mass percentage of the modified anthracite coal powder are as follows: 30-60% of boric acid, 0.5-25% of malonic acid or azelaic acid or alpha-alanine or a mixture of two or three thereof; 0.5-25% of dodecyl dimethyl benzyl ammonium chloride or cationic cellulose polymer or sodium stearate lactate or a mixture of two or three thereof; 0.5-20% of phthalic acid dicyclohexyl ester or triphenyl phosphate or a mixture of the two. The method for coking by using the modified anthracite coal powder includes the following steps: step 1, modifying anthracite coal; and step 2, weighing the modified anthracite coal and the coal for coking according to 1-50% of the mass of the coking blending coal, and blending the coal for coking according to the conventional production process. In the method, a large amount of expensive organic reagents are used, and some reagents (such as phthalic acid esters) are environmental hormone substances, so additional waste gas purification facilities are required to meet the environmental protection standards.

[0004] In addition, the existing disclosed patent cannot significantly change the quality of high-rank coal, so that the high-rank coal has the caking characteristics of high-quality coking coal such as fat coal, and there is also a lack of a corresponding coal blending coking method, which can realize the direct replacement of high-rank coal for part of coking coal or fat coal, and significantly reduce the production cost of coal blending coking. SUMMARY

[0005] The present application aims to provide a method for coking by using modified high-rank coal blending, so as to solve the problem of insufficient utilization of high-rank coal in the prior art, expand the source of coking coal resources, reduce the production cost of coal blending coking, and realize the efficient and full utilization of coal resources.

[0006] The present application considers the advantages of high-rank coal resource utilization, directional modification core technology and coal blending synergy mechanism, activates the high carbon skeleton advantage of high-rank coal through mild modification, and then makes up for the lack of adhesion through synergistic multi-element coal blending technology, through component complementation and reaction process regulation, restructures the liquid-solid dynamic balance in the coking process, and finally realizes the green coking new path of high-rank coal high value, main coking coal reduction and coke quality stabilization.

[0007] The high-rank coal is modified first in the present application, and the modification method used is simple to operate and low in cost. Through modification, lean coal and other high-rank coal can be used as coking fertilizer coal; then, by changing the blending ratio of different coals, high-quality coke can be prepared, and the coking coal resources are expanded. The performance of the coke produced by the present application is as follows: the crushing strength M 40 ≥75%, the abrasion resistance M 10 ≤8.5%, the reactivity CRI≤35%, and the strength after reaction CSR≥50%.

[0008] The present application provides a method for coking by blending modified high-rank coal, which comprises the following steps: First step: the high-rank coal is crushed to a particle size of 80-150 mesh, mixed with water and Ca-Fe-based catalyst, and then placed in a high-temperature and high-pressure reaction kettle. The reaction kettle is filled with reducing gas, the pressure is set to 3-5 MPa, the reaction temperature is 320-360℃, and the residence time is 30-90 min. After the reaction kettle is cooled, the product is discharged and subjected to solid-liquid separation, and the obtained solid product is the modified high-rank coal; Second step: the blending ratio of the raw coal is as follows: the modified high-rank coal is 5%-8%, the fat coal or gas fat coal is 20%-30%, the lean coal is 15%-22%, the lean coal is 13%-18%, the gas coal is 8%-15%, and the 1 / 3 coking coal or coking coal is 20%-27%. The particle size of the above raw coal is as follows: the particle size of 40%-45% of the raw coal is ≤0.5 mm, the particle size of 45%-50% of the raw coal is 0.5-3 mm, and the particle size of 10%-15% of the raw coal is >3 mm.

[0009] Third step: the modified high-rank coal is pre-mixed with 7%-10% of water, and then stirred quickly and uniformly. Then, the remaining raw coal is added, and 7%-10% of water is added to the total mass of the dry coal and stirred uniformly. The raw coal is subjected to ramming treatment by a ramming machine, and then enters a carbonization chamber and is heated to 1000-1100℃ and kept at a constant temperature for 100-140 min. After cooling to room temperature, the coke product is obtained.

[0010] In the first step, the Ca-Fe-based catalyst has Ca and Fe as active components, and when the mass ratio of Ca to Fe is 30-60:40-70, a high-stability crystal structure is formed, which has certain catalytic activity, can promote the hydrogenation reaction of coal, and improve the caking property of coal.

[0011] In the modification method of the high-rank coal, the mass ratio of the coal powder, water and Ca-Fe-based catalyst is 1:0.8-2:0.03-0.06.

[0012] The reducing gas is a mixture containing carbon monoxide, wherein the volume percentage of CO is > 65%, and the remaining gas can be hydrogen or methane. Hydrogen is a common and strong reducing gas, which can provide active hydrogen for the reaction and is beneficial to the cracking and hydrogenation reaction of coal.

[0013] Preferably, the high-rank coal generally refers to a kind of coal with high coalification degree but relatively weak caking property, including lean coal and lean-fat coal. The high-rank coal can be selected from one or both of lean coal and lean-fat coal mixed in any ratio.

[0014] The beneficial effects of the present application are as follows: (1) The purpose of the present application is to develop a directional modification technology for high-rank coal according to the characteristics of high fixed carbon, low volatile matter, high inert component, microporous densification, low caking property, high reaction inertness, highly condensed aromatic skeleton and short side chain, so as to replace part of coking fat coal, improve the utilization rate of coal resources, and improve the efficiency and quality of coking production.

[0015] (2) The modified high-rank coal is reasonably blended with other coking coals. The modified high-rank coal is used in combination with main coking coal and fat coal. Through complementary optimization, the unique caking and swelling properties of the modified high-rank coal are combined to ensure sufficient caking phase and maintain appropriate inert component content, thereby improving the micro-pore structure and crack development degree of coke. The particle size grading of the modified coal and other coal species is controlled to enhance the contact area and packing density between coal particles, which is beneficial to the uniform penetration of colloid and the development of mesophase. The total moisture content of the blended coal is stabilized at 7%-10%, and the moderate moisture content is beneficial to the sliding and compaction between particles, thereby improving the bulk density. It is further found that when the modified high-rank coal is used for blending, pre-watering can effectively wet the surface of the modified high-rank coal particles, stimulate the surface activity, improve the dispersibility and binding force with subsequent raw coal, and enhance the pre-caking effect at low temperature, thereby improving the coke strength after reaction (CSR). These synergistic control means can optimize the blending structure, so that the key quality indicators such as M 40 , and CSR of coke reach a high level, meeting the demand of the metallurgical industry and other industries for high-quality coke, and improving the competitiveness of coke in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the Oa expansion curve of lean coal, modified lean coal and fat coal in Example 1. DETAILED DESCRIPTION

[0017] The present invention is further illustrated below by way of examples, but is not limited to the following examples. Example 1

[0018] 1. Preparation of modified high-rank coal First, a Ca-Fe-based catalyst was prepared with a Ca:Fe mass ratio of 50:50. The preparation method was as follows: calcium nitrate tetrahydrate and iron nitrate nonahydrate were weighed, each prepared into a 1 mol / L solution, and then mixed. In a constant-temperature water bath at 60°C, ammonium carbonate solution was added dropwise to the mixed solution until the pH reached 8.0, forming a precipitate. The precipitate was washed with deionized water and anhydrous ethanol, filtered, and dried at 105°C for 12 hours. The dried solid was ground into a fine powder and calcined in a muffle furnace at a rate of 5°C / min to 600°C for 4 hours. After cooling naturally, the powder was ground and sieved to obtain the Ca-Fe-based catalyst. This method, through co-precipitation and calcination, results in a highly stable crystalline structure.

[0019] The lean coal powder crushed to a particle size of 80-150 mesh is mixed with water and a Ca-Fe-based catalyst and placed in a high-temperature and high-pressure reactor (the mass ratio of coal powder: water: Ca-Fe-based catalyst is 1:1:0.03). The reactor is filled with reducing gas, the pressure is set to 4MPa, the reaction temperature is 340℃, and the residence time is 60min. After the reactor is cooled, the product is discharged and solid-liquid separation is carried out. The solid product obtained is the modified lean coal. The indicators of the modified lean coal obtained are as follows: dry basis ash content Ad is 9.60, and the bonding index G is 80.12, which has the bonding characteristics of coke fat coal. The Oa expansion curves of lean coal (ML), modified lean coal (MML) and fat coal (FC) are shown as follows: Figure 1 As shown in the figure, T1 is the softening temperature, T2 is the expansion temperature, and T3 is the solidification temperature.

[0020] 2. Coal blending The following coal blending ratio is adopted in percentage by mass: modified coal is 5%, fat coal is 25%, lean coal is 20%, lean coal is 15%, gas coal is 10%, and 1 / 3 coking coal is 25%; the particle size of the above raw coal is ≤0.5mm, accounting for 43%, 0.5-3mm accounts for 47%, and >3mm accounts for 10%.

[0021] 3. Coal blending for coking The modified lean coal is premixed with 9% of water by mass, and is stirred rapidly until uniform; then the remaining raw coal is added, and 9% of water by mass of the total dry coal in the second step is added and stirred until uniform; the coal is treated by stamping with a stamping machine, and then is heated to 1050 DEG C in a carbonization chamber and kept at this temperature for 120 minutes, and the coke product is obtained after cooling to room temperature.

[0022] The modified high rank coal of the present application is reasonably blended with other coking coals, which can optimize the coal blending structure, so that the crushing strength M 40 , and the post-reaction strength CSR of the coke reach a high level, and meet the demand of the metallurgical industry and other industries for high-quality coke.

[0023] Table 1: Coke quality indicators

[0024] The conventional coking process in Table 1 uses the existing method, and does not use modified coal (i.e. modified lean coal) compared with the present embodiment. Example 2

[0025] 1. Preparation of modified high rank coal The pulverized lean coal with a particle size of 80-150 mesh is mixed with water and Ca-Fe based catalyst (prepared in Example 1), and is placed in a high temperature and high pressure reaction kettle (the mass ratio of coal powder: water: Ca-Fe is 1:0.8:0.03), and is filled with reducing gas in the reaction kettle, and the pressure is set to 4 MPa, the reaction temperature is 340 DEG C, and the residence time is 60 minutes. After the reaction kettle is cooled, the product is discharged and subjected to solid-liquid separation, and the obtained solid product is the modified lean coal. The indexes of the obtained modified lean coal are as follows: dry basis ash Ad is 9.62, and caking index G is 76.18.

[0026] 2. Coal blending The following coal blending ratio by mass percentage is used: modified coal is 6%, fat coal is 24%, lean coal is 21%, lean coal is 17%, gas coal is 8%, and 1 / 3 coking coal is 24%; the proportion of raw coal with a particle size of ≤0.5 mm is 43%, the proportion of raw coal with a particle size of 0.5-3 mm is 45%, and the proportion of raw coal with a particle size of >3 mm is 12%.

[0027] 3. Coking of coal blending The modified lean coal is premixed with 9% of water by mass, and is stirred rapidly until uniform; then the remaining raw coal is added, and 9% of water by mass of the total dry coal in the second step is added and stirred until uniform; the coal is treated by stamping with a stamping machine, and then is heated to 1050 DEG C in a carbonization chamber and kept at this temperature for 120 minutes, and the coke product is obtained after cooling to room temperature.

[0028] The modified high rank coal of the present application is reasonably blended with other coking coals, which can optimize the coal blending structure, so that the crushing strength M 40, reaction strength CSR and other key quality indicators reach a high level, meeting the demand of the metallurgical industry for high-quality coke.

[0029] Table 2 Coke quality indicators Example 3

[0030] 1. Preparation of modified high-rank coal The pulverized lean coal powder with a particle size of 80-150 mesh was mixed with water and a Ca-Fe-based catalyst (prepared in Example 1) and then placed in a high-temperature and high-pressure reaction kettle (the mass ratio of coal powder: water: Ca-Fe was 1:1:0.04). The reaction kettle was filled with reducing gas, and the pressure was set to 4 MPa, the reaction temperature was set to 340℃, and the residence time was set to 60 min. After the reaction kettle was cooled, the product was discharged and subjected to solid-liquid separation, and the obtained solid product was the modified lean coal. The indicators of the obtained modified lean coal were as follows: dry basis ash content Ad was 9.65, and caking index G was 80.17.

[0031] 2. Coal blending The following coal blending ratio by mass percentage was used: modified coal 8%, gas-fat coal 22%, lean coal 20%, lean coal 15%, gas coal 10%, and coking coal 25%. The particle size of the raw coal was as follows: ≤0.5 mm accounted for 42%, 0.5-3 mm accounted for 47%, and >3 mm accounted for 11%.

[0032] 3. Coal blending and coking The modified lean coal was first pre-mixed with 9% of its mass of water, and then rapidly stirred until uniform. Then the remaining raw coal was added, and 9% of the total mass of the dry coal was added to the mixture and stirred until uniform. The mixture was then subjected to ramming treatment using a ramming machine, and then heated to 1050℃ in a carbonization chamber and maintained at this temperature for 120 min. After cooling to room temperature, the coke product was obtained.

[0033] The modified high-rank coal of the present application can be reasonably blended with other coking coals to optimize the coal blending structure, improve the crushing strength M 40 , reaction strength CSR and other key quality indicators reach a high level, meeting the demand of the metallurgical industry for high-quality coke.

[0034] Table 3 Coke quality indicators

[0035] Comparative Example 1. Preparation of modified high-rank coal The lean and meager coal powder with a particle size of 80-150 mesh is mixed with water and the Ca-Fe-based catalyst (Example 1) and then placed in a high-temperature and high-pressure reaction kettle (the mass ratio of the coal powder, water and Ca-Fe-based catalyst is 1:1:0.03), the reaction kettle is filled with a reducing gas, the pressure is set to 4 MPa, the reaction temperature is 340 DEG C, and the residence time is 60 min. After the reaction kettle is cooled, the product is discharged and subjected to solid-liquid separation, and the obtained solid product is the modified lean and meager coal. The indexes of the obtained modified lean and meager coal are as follows: the dry basis ash content Ad is 9.36, and the caking index G is 80.21.

[0036] 2. Coal blending The following coal blending ratio in mass percentage is adopted: the modified coal is 9%, the fat coal is 21%, the lean coal is 21%, the meager coal is 17%, the gas coal is 8%, and the coking coal is 24%; the particle size of the raw coal is as follows: the particle size of 40% of the raw coal is less than or equal to 0.5 mm, the particle size of 45% of the raw coal is 0.5-3 mm, and the particle size of 15% of the raw coal is greater than 3 mm.

[0037] 3. Coking of the blended coal The modified lean and meager coal is premixed with 9% of water based on the mass of the modified lean and meager coal, and then rapidly stirred until uniform; then the remaining raw coal is added, and 9% of water based on the total mass of the dry coal in the second step is added and stirred until uniform; the mixture is subjected to ramming treatment by using a ramming machine, and then enters a carbonization chamber and is heated to 1050 DEG C and kept at this temperature for 120 min, and the coke product is obtained after being cooled to room temperature.

[0038] The modified high-rank coal and other coking coals are reasonably blended, the coal blending structure is optimized, the crushing strength M 40 of the coke is improved, the key quality indexes such as the strength after reaction CSR reach a high level, and the demand of the metallurgical industry and other industries for high-quality coke is met.

[0039] Table 4. Coke quality indexes

[0040] The modified high-rank coal and other coking coals are reasonably blended, the coal blending structure is optimized, and part of the coking and fat coal is replaced by the modified high-rank coal, so that the utilization rate of coal resources is improved, and the efficiency and quality of coking production are improved: the crushing strength M 40 of the coke is improved, the abrasion resistance M 10 is reduced, the reactivity CRI is reduced, and the strength after reaction CSR is improved. The crushing strength M 40 is improved, the crushing resistance of the coke is enhanced, the coke is not easy to be broken during transportation and charging into a blast furnace, the loss of "large pieces into small pieces" after charging into the blast furnace is reduced, and the integrity of the coke framework in the blast furnace is ensured; the abrasion resistance M 10The coke abrasion resistance is improved, powder is not easy to be generated under the airflow scouring and material friction in the blast furnace, and the risk of "clogging" in the blast furnace (powder will hinder the gas flow and the descending of the furnace charge) is reduced; the reactivity CRI is reduced, the activity of the coke in the blast furnace is reduced, the coke is not easy to be "dissolved and lost" due to excessive reaction, and the effective action time in the blast furnace is prolonged; the strength CSR after reaction is improved, and even after partial reaction in the high-temperature reducing environment of the blast furnace, the coke can still maintain high structural strength, continuously support the furnace charge and maintain the smooth passage of the gas channel, and the blast furnace is prevented from being out of order (such as material suspension and collapse) due to coke "powdering". However, in the comparative example, due to the excessive addition (more than 8%) of the modified coal, the crushing strength M 40 of the coke is reduced, the abrasion resistance M 10 of the coke is increased, the reactivity CRI is increased, and the strength CSR after reaction is basically unchanged, which indicates that the "synergistic coking ability" of the modified coal has a threshold, and excessive addition will dilute the core role of the high-quality coal and also introduce "unfavorable structures", so that the coke reactivity is increased. Therefore, the replacement of the modified high-rank coal for the high-quality coal is "limited replacement", and the best addition ratio (to avoid excessive addition) needs to be determined through experiments, so that the "resource utilization and coke quality" win-win can be realized.

[0041] The technical scheme provided by the present application not only relieves the shortage pressure of the high-quality coking coal through "replacement of the modified high-rank coal for the high-quality coal", but also reduces the cost and risk of coking and blast furnace smelting through improving the coke quality, and finally realizes the multiple benefits of "efficient resource utilization-stable production-stable operation-product quality improvement-economic cost optimization".

Claims

1. A method for coking using modified high-rank coal, characterized in that The following steps are involved: The first step is to grind high-rank coal into coal powder with a particle size of 80-150 mesh, mix it with water and a Ca-Fe-based catalyst, and place it in a high-temperature and high-pressure reactor. The reactor is filled with reducing gas, the pressure is set to 3-5 MPa, the reaction temperature is 320-360°C, and the residence time is 30-90 minutes. After the reactor is cooled, the product is discharged and solid-liquid separation is performed. The resulting solid product is the modified high-rank coal. Step 2: Use the following coal blending ratios by mass: 5% to 8% for modified high-rank coal, 20% to 30% for fat coal or gas-fat coal, 15% to 22% for lean coal, 13% to 18% for lean coal, 8% to 15% for gas coal, and 20% to 27% for 1 / 3 coking coal or coking coal; of the above raw coals, the proportion of particle size ≤ 0.5mm is 40% to 45%, the proportion of particle size 0.5-3mm is 45% to 50%, and the proportion of particle size > 3mm is 10% to 15%; Step 3: Premix the modified high-rank coal with 7%-10% of its mass of water and stir quickly until uniform; then add the remaining raw coal, and then add water at 7%-10% of the total mass of the dry coal in the second step and stir evenly; use a tamping machine to tamp the mixture, and then enter the carbonization chamber and heat to 1000-1100℃ and keep the temperature constant for 100-140 minutes. After cooling to room temperature, the coke product is obtained.

2. The method for coking using modified high-rank coal according to claim 1, characterized in that: The Ca-Fe-based catalyst has active components of Ca and Fe. When the mass ratio of Ca to Fe is 30-60:40-70, a highly stable crystal structure is formed. The catalyst has catalytic activity, can promote the hydrogenation reaction of coal, and improve the adhesion of coal.

3. The method for coking using modified high-rank coal according to claim 1, characterized in that: In the modification method of high-rank coal, the raw material ratio is: the mass ratio of coal powder, water, and Ca-Fe-based catalyst is 1:0.8-2:0.03-0.

06.

4. The method for coking using modified high-rank coal according to claim 1, characterized in that: The reducing gas is a mixture containing carbon monoxide, wherein the volume percentage of CO is greater than 65%; the mixed gas also includes hydrogen or methane.

5. The method for coking using modified high-rank coal according to claim 1, characterized in that: High-rank coal is a mixture of one of lean coal and lean coal, or both in any proportion.

6. The method for coking using modified high-rank coal according to claim 1, characterized in that: The coke properties prepared by this method: crushing strength M 40 ≥75%, wear resistance M 10 ≤8.5%, reactivity CRI≤35%, post-reaction strength CSR≥50%.

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