A method for preparing new blast furnace charge using sintered return ore

Abstract

This application provides a method for preparing new blast furnace charge using sintered return ore, belonging to the field of iron and steel metallurgical technology. The method includes pre-treating sintered return ore, pulverized coal, and a binder by crushing, screening, and drying; wherein the pulverized coal includes bituminous coal and coke powder; uniformly mixing the pre-treated sintered return ore, bituminous coal, coke powder, and binder to obtain a mixture; heating and cold-pressing the mixture to prepare a cold-pressed billet; and carbonizing and cooling the cold-pressed billet to prepare a sintered return ore composite iron coke product. This method effectively solves the problem of inefficient and low-carbon utilization of sintered return ore. Furthermore, using sintered return ore to replace iron concentrate in the preparation of composite iron coke significantly reduces production costs while ensuring high reactivity, achieving a low-cost transformation.

Description

Technical Field

[0001] This application belongs to the field of iron and steel metallurgy technology, specifically relating to a method for preparing new blast furnace charge using sintered return ore. Background Technology

[0002] Sintered ore return is sinter with a particle size of less than 5 mm obtained after granulation and screening. Its main components are iron (TFe) and calcium oxide (CaO). Currently, sintered ore return is mainly recycled back to the sintering process for reuse. A reasonable proportion of sintered ore added (5%–20%) is beneficial to improving the permeability of the sinter bed and increasing the quality and yield of sintered ore. However, adding more than 20% of ore will reduce the yield of sintered products and increase costs and carbon emissions. At the same time, there are strict requirements on the particle size of sintered ore during the sintering process, generally not exceeding 5 mm. Among them, particles of 3 mm to 5 mm are the most ideal. Particles that are too fine (<1 mm) will lead to difficulty in nucleation, seriously deteriorate the permeability of the bed, increase fuel consumption, and reduce the quality of sintered ore. Therefore, achieving efficient and low-carbon utilization of sintered ore has become a key common problem that the steel industry urgently needs to solve.

[0003] Composite iron coke is a novel low-carbon blast furnace burden made from low-rank coal powder and iron-containing materials through mixing, briquetting, and carbonization. Iron (Fe) and calcium (Ca) in composite iron coke play a significant catalytic role in the gasification reaction of carbon, thus giving it high reactivity. Appropriate application of iron coke in the blast furnace can lower the temperature of the heat reserve zone, promote the reduction of iron-containing burdens, and reduce the coke ratio, thereby reducing energy consumption and CO2 emissions in blast furnace ironmaking. Currently, iron coke production mainly relies on high-cost iron concentrate, resulting in high overall production costs. There is an urgent need to find a new type of iron-containing raw material that can significantly reduce production costs while maintaining the high reactivity of composite iron coke. Summary of the Invention

[0004] Therefore, the purpose of this application is to provide a method for preparing new blast furnace charge using sintered return ore, thereby solving at least one of the technical problems mentioned in the background art.

[0005] To address the aforementioned problems, this application provides a method for preparing new blast furnace charge using sintered return ore, comprising:

[0006] The sintered return ore, pulverized coal, and binder are respectively subjected to crushing, screening, and drying pretreatment; wherein the pulverized coal includes bituminous coal and coke powder;

[0007] The pretreated sintered return ore, bituminous coal, coke powder, and binder are uniformly mixed to obtain a mixture;

[0008] The mixture is heated and then cold-pressed to prepare a cold-pressed blank.

[0009] The cold-pressed billet is carbonized and cooled to prepare sintered return ore composite iron coke product.

[0010] Optionally, the bituminous coal includes 1 / 3 coking coal, lean coal, and prime coking coal; during the coal blending process, the mass ratio of the 1 / 3 coking coal, the prime coking coal, the lean coal, and the coke powder is fixed at 9:2:2:1.

[0011] Optionally, the particle size of the pretreated sintered return ore is less than 1 mm; the particle size of the pulverized coal and the coke powder is less than 3 mm; and the particle size of the binder is less than 2 mm.

[0012] Optionally, the step of uniformly mixing the pretreated sintered return ore, the bituminous coal, the coke powder, and the binder to obtain a mixture specifically includes:

[0013] The pretreated sintered return ore, bituminous coal, coke powder, and binder are uniformly mixed using a high-power mixer to obtain a mixture.

[0014] In this mixture, by mass percentage, sintered return ore accounts for 10% to 40%, bituminous coal accounts for 55% to 80%, coke powder accounts for 5% to 10%, and the binder accounts for 3% to 7%.

[0015] Optionally, the adhesive is formulated at a ratio of 3% to 7%, specifically:

[0016] The binder is uniformly mixed with the coal powder and the sintered return ore in the form of solid particles, with a ratio of 3% to 7% of the total mass of the coal powder and the sintered return ore.

[0017] Optionally, the step of heating the mixture and obtaining a cold-pressed blank using a cold-pressing device includes:

[0018] The mixture is heated using a mixture heating device, wherein the heating temperature is 70℃~90℃;

[0019] The heated mixture is cold-pressed using a cold-pressing molding device to obtain a cold-pressed blank; wherein the molding pressure is 3t / cm to 7t / cm.

[0020] Optionally, the step of carbonizing and cooling the cold-pressed billet to obtain the sintered return ore composite iron coke product includes:

[0021] Based on a four-stage heating system, a vertical furnace is used to carbonize the cold-pressed billet by gas heating.

[0022] The cold-pressed billet after carbonization is cooled to room temperature by gas cooling to obtain sintered return ore composite iron coke product.

[0023] Optionally, the four-stage heating regime includes a first stage, a second stage, a third stage, and a fourth stage; the first stage heats the temperature from room temperature to 300℃ to 350℃ at a heating rate of 10℃ / min to 12℃ / min; the second stage heats the temperature from 300℃ to 350℃ to 500℃ to 550℃ at a heating rate of 2℃ / min to 3℃ / min; the third stage heats the temperature from 500℃ to 550℃ to 900℃ to 1000℃ at a heating rate of 7℃ / min to 9℃ / min; and the fourth stage maintains the temperature at 900℃ to 1000℃ for 3h to 5h.

[0024] Optionally, in the carbonization step, the gas is a high-temperature waste gas generated after the combustion of a mixture of coke oven gas and blast furnace gas.

[0025] Optionally, in the step of cooling to room temperature by gas cooling, the gas is an inert gas.

[0026] By employing the above technical solution, the present invention has at least the following beneficial effects:

[0027] This application provides a method for preparing new blast furnace charge using sintered return ore. It utilizes finely ground (<1mm) sintered return ore, which was previously difficult to utilize, as the core iron-containing raw material for composite iron coke, replacing high-cost iron concentrate. Implementation data shows that when the proportion of sintered return ore added is 10%~30%, not only is 100% efficient utilization of this type of waste resource achieved, but also, because the sintered return ore is rich in TFe and CaO, the two have a synergistic catalytic effect on the gasification reaction of carbon, keeping the reactivity of the composite iron coke stably above 60%, significantly better than the reactivity of traditional iron coke. This provides crucial support for reducing coke consumption and emissions in blast furnace ironmaking.

[0028] Using sintered return ore as the core raw material for the preparation of composite iron coke, its compressive strength is not less than 3000N, its twist strength is not less than 75%, its reactivity is more than 60%, and its post-reaction strength is maintained at more than 50%. All performance indicators show that this material has high industrial application value. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating a method for preparing new blast furnace charge using sintered return ore, as described in an embodiment of this application. Detailed Implementation

[0030] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0034] See also Figure 1 As shown in the embodiments of this application, a method for preparing new blast furnace charge using sintered return ore is provided, comprising the following steps:

[0035] Step S1 involves crushing, screening, and drying pretreatment of the sintered return ore, pulverized coal, and binder; wherein the pulverized coal includes bituminous coal and coke powder.

[0036] Step S11, Crushing process:

[0037] Jaw crusher combined with impact crusher is used to crush sintered return ore to a particle size range that meets the requirements of subsequent screening, breaking up agglomerates and eliminating large impurities;

[0038] A toothed roll crusher combined with a hammer crusher is used to crush bituminous coal to a force range that meets the requirements of subsequent screening, breaking up lumps and eliminating large impurities.

[0039] A cone crusher combined with a vertical shaft impact crusher is used to crush coke powder to a particle size range that meets the requirements of subsequent screening, breaking up agglomerates and eliminating large impurities;

[0040] A low-temperature jaw crusher is used to crush the binder, breaking the blocky and granular solid binder into easily screenable particles, thus reducing subsequent processing time.

[0041] The binder is modified asphalt, which is a black solid at room temperature with moderate softening point, volatile content and high coking value.

[0042] Using modified asphalt as a binder can prevent the problems of low-temperature asphalt's low melting point leading to agglomeration of the mixture and difficulty in dispersing the furnace charge, resulting in uneven structure of the cold-pressed billet. It also avoids the problems of high-temperature asphalt's high melting point and difficulty in melting, which makes it difficult to wet aggregate particles, leading to poor bonding and low strength of the cold-pressed billet. Furthermore, modified asphalt has low volatile matter and high coking value, effectively suppressing the cracking and agglomeration of composite iron coke during carbonization, while significantly improving its strength.

[0043] Bituminous coal includes 1 / 3 coking coal, lean coal and prime coking coal;

[0044] During the coal blending process, the mass ratio of 1 / 3 coking coal, prime coking coal, lean coal and coke powder is fixed at 9:2:2:1.

[0045] In the coal blending process, a fixed ratio of 9:2:2:1 is adopted, with 1 / 3 coking coal as the main component and a small amount of lean coal, and prime coking coal and coke powder as the secondary component. Bituminous coal is used as the main fuel, replacing part of the high-priced prime coking coal. Modified asphalt (3%~7% externally added) is selected as the binder. This can prevent the low melting point of low-temperature asphalt from causing the mixture to clump and the furnace charge to be difficult to disperse, resulting in uneven structure of the cold-pressed billet. It can also avoid the problem of high-temperature asphalt having an excessively high melting point and difficulty in melting, making it difficult to wet the aggregate particles, resulting in poor bonding effect and low strength of the cold-pressed billet. In addition, modified asphalt has the characteristics of low volatile matter and high coking value, which effectively inhibits the cracking and agglomeration of composite iron coke during the carbonization process, while significantly improving its strength.

[0046] Compared with traditional iron concentrate preparation processes, this solution significantly reduces raw material costs, while achieving a cold-pressed billet yield of over 85%, further reducing raw material loss and achieving the dual economic benefits of low cost and high yield.

[0047] Step S12, screening process:

[0048] The screen aperture is set according to the process requirements. The crushed sintered return ore, bituminous coal, coke powder and binder are screened separately using a fixed screen or a vibrating screen to obtain coal ore and binder with composite particle size requirements. The particle size of the pretreated sintered return ore is less than 1 mm; the particle size of coal powder and coke powder is less than 3 mm, and the particle size of binder is less than 2 mm.

[0049] During the screening process, overly coarse particles must be returned to the crushing stage for reprocessing.

[0050] Screening is used to ensure the uniformity of coal and binder particles.

[0051] Step S13, Drying treatment:

[0052] A rotary drum dryer is used to dry the sintered return ore particles after screening; a box dryer is used to dry the bituminous coal and coke powder particles after screening; and a vacuum dryer is used to dry the binder particles after screening. The binder drying temperature needs to be controlled within 40℃~50℃.

[0053] Drying is performed to remove free water and some bound water from sintered return ore, bituminous coal, coke powder and binder, thereby reducing the moisture content and avoiding affecting the efficiency of the carbonization process.

[0054] Step S2: The pretreated sintered return ore, bituminous coal, coke powder and binder are mixed evenly to obtain a mixture.

[0055] A high-powered mixer was used to uniformly mix sintered return ore, bituminous coal, coke powder and binder to obtain a mixture; the rotation speed was 200 r / min and the time was 10 min.

[0056] Of these, by mass percentage, sintered return ore accounts for 10% to 40%, bituminous coal accounts for 55% to 80%, coke powder accounts for 5% to 10%, and external binder accounts for 3% to 7%.

[0057] Specifically, the binder accounts for 3% to 7% of the total mass of the coal powder and sintered return ore. In other words, the binder is mixed evenly with the coal powder and sintered return ore in the form of solid particles, with a ratio of 3% to 7% of the total mass of the coal powder and sintered return ore.

[0058] Step S3: The mixture is heated and cold-pressed to prepare a cold-pressed blank.

[0059] Step S31: The mixture is heated using a mixture heating device, wherein the heating temperature is 70℃~90℃.

[0060] Specifically, the heating device for the mixture is a vertical preheater.

[0061] Step S32: The heated mixture is cold-pressed using a cold pressing forming device to obtain a cold-pressed blank; wherein the forming pressure is 3t / cm to 7t / cm.

[0062] Specifically, the cold pressing forming device is a high-pressure ball pressing test machine.

[0063] Step S4 involves carbonizing and cooling the cold-pressed billet to prepare sintered return ore composite iron coke product.

[0064] Step S41: Based on the four-stage heating system, a vertical furnace is used to carbonize the cold-pressed billet by gas heating.

[0065] The four-stage heating regime includes a first stage, a second stage, a third stage, and a fourth stage. The first stage heats the room temperature to 300℃ to 350℃ at a heating rate of 10℃ / min to 12℃ / min. The second stage heats the room temperature to 500℃ to 550℃ at a heating rate of 2℃ / min to 3℃ / min. The third stage heats the room temperature to 900℃ to 1000℃ at a heating rate of 7℃ / min to 9℃ / min. The fourth stage maintains the temperature at 900℃ to 1000℃ for 3 to 5 hours.

[0066] The process employs a four-stage heating regime: rapid heating at low temperature, slow heating at medium temperature, rapid heating at high temperature, and constant temperature holding. The first stage rapidly removes surface moisture from the raw materials, preventing structural loosening caused by moisture retention at low temperatures. The second stage involves slow heating to suppress bursting caused by the concentrated release of volatile components from the binder. The third stage rapidly increases the degree of carbonization, and the fourth stage ensures complete carbonization. The final product exhibits a compressive strength of no less than 3000N and a drum strength ≥75%, far exceeding the 2803N compressive strength and 68% drum strength of Comparative Example 1, fully meeting the mechanical performance requirements of blast furnace burden.

[0067] The gas is a high-temperature waste gas produced by the combustion of a mixture of coke oven gas and blast furnace gas; that is, the gas is a high-temperature waste gas produced by the combustion of a mixture of coke oven gas and blast furnace gas and combustion air; the high-temperature waste gas is used to perform countercurrent heating treatment on the cold-pressed billet, and the mass percentage of CO2 in the high-temperature waste gas does not exceed 10%.

[0068] Specifically, the vertical furnace is an internally heated vertical carbonization furnace. This furnace features high thermal efficiency, large production capacity, flexible adjustment of heating temperature, and low furnace top temperature.

[0069] Step S42: The carbonized cold-pressed billet is cooled to room temperature by gas cooling to obtain sintered return ore composite iron coke product.

[0070] Nitrogen gas is introduced into the cooling end of the internally heated vertical carbonization furnace. The nitrogen gas undergoes counter-current heat exchange with the descending high-temperature sintered return ore composite coke (900℃~1000℃). The extracted nitrogen gas is heated to 800℃ and sent to a waste heat boiler to produce high-temperature, high-pressure steam, which drives a steam turbine generator to produce electricity. The nitrogen gas, cooled by the boiler (approximately 150℃), is then dedusted and sent back into the cooling chamber by a circulating fan, forming a closed-loop circulation system. The sintered return ore composite coke is discharged after being cooled to below 100℃.

[0071] The method for utilizing sintered ore back to its source achieves low-carbon, high-value-added utilization. This method is simple, easy to operate, and produces cold-pressed billets and sintered ore-returned ore composite iron-coke products with high yields, excellent metallurgical properties, and promising industrial application prospects. This sintered composite iron-coke product can effectively replace some coke in blast furnace smelting, helping to reduce coke consumption and CO2 emissions, resulting in significant economic and environmental benefits.

[0072] In this embodiment of the invention, the chemical composition of the sintered return ore used is shown in Table 1, and the particle size of the sintered return ore is less than 1 mm; the industrial analysis of the bituminous coal and coke powder used is shown in Table 2, and the particle size of the bituminous coal and coke powder is less than 3 mm; the basic properties of the binder used are shown in Table 3; and the gas composition of the mixed gas used is shown in Table 4.

[0073] Table 1 Chemical composition of sintered return ore (mass percentage / %)

[0074]

[0075] Table 2 Industrial Analysis of Pulverized Coal (mass percentage / %)

[0076]

[0077] Table 3 Basic Properties of Asphalt

[0078]

[0079] Table 4. Gas composition of the gas mixture (volume percentage / %)

[0080]

[0081] Comparative Example 1

[0082] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0083] Step S1, Preparation of cold-pressed billet: Mix 30% iron ore powder (80% of which are below 74μm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (low-temperature asphalt). Heat the low-temperature asphalt into a liquid and mix it evenly with the coal mixture to obtain mixture 1. Cold press the mixture with a molding pressure of 6t / cm to obtain the cold-pressed billet.

[0084] Step S2, Preparation of Composite Iron Coke Sample: The cold-pressed billet is loaded into a vertical shaft furnace, and the iron coke is carbonized by high-temperature exhaust gas. The cold-pressed billet is heated from room temperature to 550℃ at a heating rate of 3℃ / min in the vertical shaft furnace; then heated from 550℃ to 1000℃ at a heating rate of 5℃ / min; finally, it is kept at 1000℃ for 4 hours. After cooling with nitrogen, the composite iron coke product is obtained.

[0085] Tests showed that the cold-pressed billet obtained in Comparative Example 1 had a compressive strength of 450 N and a yield of 65%; the composite iron coke had a compressive strength of 2803 N, a drum strength of 68%, a reactivity of 60%, and a post-reaction strength of 40.01%; the iron coke exhibited cracking phenomena.

[0086] Example 1

[0087] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0088] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 1mm), 45% 1 / 3 coking coal, 10% coking coal, 10% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press the mixture 1 with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0089] Step S2, the preparation of composite iron coke, is the same as in Comparative Example 1.

[0090] Tests showed that the cold-pressed billet obtained in Example 1 had a compressive strength of 805 N, a yield of 85%, a compressive strength of 3200 N for sintered return ore composite coke, a drum strength of 75.42%, a reactivity of 65.33%, and a post-reaction strength of 50.31%; slight cracking of the coke was observed.

[0091] Example 2

[0092] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0093] Step S1, the preparation of the cold-pressed blank is the same as in Example 1.

[0094] Step S2, Preparation of Composite Iron Coke: Cold-pressed billets are loaded into a vertical shaft furnace, where the iron coke is carbonized using high-temperature exhaust gas. The cold-pressed billets are heated from room temperature to 300℃ at a rate of 8℃ / min; then from 300℃ to 550℃ at a rate of 2℃ / min; subsequently from 550℃ to 1000℃ at a rate of 9℃ / min; finally, the temperature is held at 1000℃ for 3 hours. After cooling with nitrogen, the sintered return ore composite iron coke product is obtained.

[0095] Tests showed that the cold-pressed billet obtained in Example 2 had a compressive strength of 805 N, a yield of 85%, a compressive strength of 3500 N for the sintered return ore composite iron coke, a drum strength of 80.42%, a reactivity of 65.33%, and a post-reaction strength of 53.31%; the composite iron coke did not exhibit any cracking phenomenon.

[0096] Example 3

[0097] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0098] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 10% sintered return ore (particle size less than 1mm), 58% 1 / 3 coking coal, 13% coking coal, 13% lean coal, 6% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press the mixture with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0099] Step S2, the preparation of composite iron coke, is the same as in Example 2.

[0100] Tests showed that the cold-pressed billet obtained in Example 3 had a compressive strength of 550N and a yield of 85%. The sintered return ore composite iron coke had a compressive strength of 3000N, a drum strength of 76.42%, a reactivity of 60.33%, and a post-reaction strength of 55.31%. The composite iron coke did not exhibit any cracking phenomenon.

[0101] Example 4

[0102] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0103] Step S1, Preparation of cold-pressed billet: The raw materials are mixed evenly according to the following formula: 20% sintered return ore (particle size less than 1mm), 51% 1 / 3 coking coal, 11% prime coking coal, 11% lean coal, 7% coke powder and 5% binder (low temperature asphalt). The mixture is heated to 80℃ and cold-pressed by rollers at a pressure of 6t / cm to obtain cold-pressed billet.

[0104] Step S2, the preparation of the composite iron coke product is the same as in Example 2.

[0105] Tests showed that the cold-pressed billet obtained in Example 4 had a compressive strength of 605 N and a yield of 85%; the sintered return ore composite iron coke had a compressive strength of 3100 N, a drum strength of 77.32%, a reactivity of 62.22%, and a post-reaction strength of 52.39%; the composite iron coke showed no cracking.

[0106] Example 5

[0107] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0108] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 1mm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press the mixture with rollers at a pressure of 6t / cm to obtain cold-pressed billet.

[0109] Step S2, the preparation of the sintered return ore composite iron coke product is the same as in Example 2.

[0110] Tests showed that the cold-pressed billet obtained in Example 5 had a compressive strength of 820 N, the sintered return ore composite iron coke had a compressive strength of 3600 N, the drum strength was 80%, the reactivity was 65.33%, and the post-reaction strength was 52.01%; the composite iron coke did not exhibit any cracking phenomenon.

[0111] Example 6

[0112] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0113] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 40% sintered return ore (particle size less than 1mm), 39% 1 / 3 coking coal, 8% prime coking coal, 8% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press the mixture with rollers at a pressure of 6t / cm to obtain cold-pressed billet.

[0114] Step S2, the preparation of sintered return ore composite iron coke products is the same as in Implementation Case 2.

[0115] Tests showed that the cold-pressed billet obtained in Example 6 had a compressive strength of 500N and a yield of 85%. The sintered return ore composite iron coke had a compressive strength of 2400N, a drum strength of 63%, a reactivity of 68.31%, and a post-reaction strength of 48%. The composite iron coke did not exhibit any cracking phenomenon.

[0116] Example 7

[0117] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (raw ore), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (modified bitumen). Heat the mixture to 80°C and cold press the mixture with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0118] Step S2, the preparation of the sintered return ore composite iron coke product is the same as in Example 2.

[0119] Tests showed that the cold-pressed billet obtained in Example 7 had a compressive strength of 355N and a yield of 70%. The sintered return ore composite coke had a compressive strength of 1900N, a drum strength of 55%, a reactivity of 74%, and a post-reaction strength of 34%. The composite coke did not exhibit any cracking phenomenon.

[0120] Example 8

[0121] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0122] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 4mm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press it with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0123] Step S2, the preparation of the sintered return ore composite iron coke product is the same as in Example 2.

[0124] Tests showed that the cold-pressed billet obtained in Example 8 had a compressive strength of 401N and a yield of 72%. The sintered return ore composite iron coke had a compressive strength of 2000N, a drum strength of 58%, a reactivity of 72%, and a post-reaction strength of 38.35%. The composite iron coke did not exhibit any cracking phenomenon.

[0125] Example 9

[0126] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0127] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 3mm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (externally added). Heat the mixture to 80℃ and cold press the mixture with rollers at a pressure of 6t / cm to obtain cold-pressed billet.

[0128] Step S2, the preparation of sintered return ore composite iron coke products is the same as in Implementation Case 2.

[0129] Tests showed that the cold-pressed billet obtained in Example 9 had a compressive strength of 455 N and a yield of 75%; the sintered return ore composite iron coke had a compressive strength of 2356 N, a drum strength of 65%, a reactivity of 68%, and a post-reaction strength of 44.33%; the composite iron coke showed no cracking.

[0130] Example 10

[0131] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0132] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 2mm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press it with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0133] Step S2, the preparation of the sintered return ore composite iron coke product is the same as in Example 2.

[0134] Tests showed that the cold-pressed billet obtained in Example 10 had a compressive strength of 560 N and a yield of 75%. The sintered return ore composite coke had a compressive strength of 2556 N, a drum strength of 70%, a reactivity of 66%, and a post-reaction strength of 47.31%. The composite coke did not exhibit any cracking phenomenon.

[0135] Example 11

[0136] A method for preparing new blast furnace charge using sintered return ore includes the following steps:

[0137] Step S1, Preparation of cold-pressed billet: Mix the raw materials evenly according to the following formula: 30% sintered return ore (particle size less than 1mm), 45% 1 / 3 coking coal, 10% prime coking coal, 10% lean coal, 5% coke powder and 5% binder (modified asphalt). Heat the mixture to 80℃ and cold press the mixture with rollers at a pressure of 6t / cm to obtain the cold-pressed billet.

[0138] Step S2, the preparation of sintered return ore composite iron coke products is the same as in Implementation Case 2.

[0139] Tests showed that the cold-pressed billet obtained in Example 11 had a compressive strength of 820 N, the sintered return ore composite iron coke had a compressive strength of 3600 N, the drum strength was 80%, the reactivity was 65.33%, and the post-reaction strength was 52.01%; the composite iron coke showed no cracking.

[0140] Analyzing the above embodiments, under the premise that the sinter particle size is no greater than 1 mm, the amount of sintered return ore added is 10%–30%, the proportion of bituminous coal is 63%–85%, the proportion of coke powder is 5%–7%, and the binder is 5% modified asphalt. The iron coke is carbonized using high-temperature waste gas. The cold-pressed billet is heated from room temperature to 300°C in a vertical furnace at a heating rate of 8°C / min; then from 300°C to 550°C at a heating rate of 2°C / min; then from 550°C to 1000°C at a heating rate of 9°C / min; finally, it is held at 1000°C for 3 hours. After cooling with nitrogen, the sintered return ore composite iron coke product is obtained. The carbonization regime results in a cold-pressed billet with a compressive strength of over 500 N, a composite iron coke with a compressive strength of not less than 3000 N, a cross-linking strength of not less than 75%, a reactivity of over 60%, and a post-reaction strength maintained above 50%, exhibiting excellent economic and metallurgical properties. As can be seen from the above examples, high-performance composite iron coke can be prepared by using sintered return ore, bituminous coal, and coke powder as raw materials, and by optimizing coal and ore blending, sintered return ore particle size, binder type, and synergistically controlling the carbonization process. Its mechanical strength fully meets the standards for blast furnace use, while also possessing high reactivity and post-reaction strength comparable to metallurgical coke. With excellent overall performance, it is a high-quality ironmaking raw material.

[0141] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0142] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for producing new blast furnace burden from sintered return fines, characterized in that, The application relates to a sintered return fine composite iron coke product and a preparation method thereof. The sintered return fine, coal powder and binder are respectively crushed, screened and dried; wherein the coal powder comprises bituminous coal and coke powder; The sintered return fine, the bituminous coal, the coke powder and the binder are uniformly mixed to obtain a mixture; The mixture is heated and cold-pressed to prepare a cold-pressed blank; The cold-pressed blank is carbonized and cooled to prepare the sintered return fine composite iron coke product; The bituminous coal comprises 1 / 3 coking coal, lean coal and main coking coal; during coal blending, the mass ratio of the 1 / 3 coking coal, the main coking coal, the lean coal and the coke powder is fixed as 9:2:2:1; The carbonization and cooling of the cold-pressed blank to obtain the sintered return fine composite iron coke product comprises: The cold-pressed blank is carbonized by a shaft furnace in a gas heating mode based on a four-stage temperature rising system; The cold-pressed blank after the carbonization treatment is cooled to room temperature by a gas cooling mode to obtain the sintered return fine composite iron coke product; The four-stage temperature rising system comprises a first stage, a second stage, a third stage and a fourth stage; the first stage is raised from room temperature to 300-350 DEG C at a temperature rising rate of 10-12 DEG C / min; the second stage is raised from 300-350 DEG C to 500-550 DEG C at a temperature rising rate of 2-3 DEG C / min; the third stage is raised from 500-550 DEG C to 900-1000 DEG C at a temperature rising rate of 7-9 DEG C / min; and the fourth stage is kept at 900-1000 DEG C for 3-5 h.

2. The method for preparing new blast furnace burden from sintered return fines according to claim 1, characterized in that, The particle size of the sintered return fine after the pretreatment is less than 1 mm; the particle size of the coal powder and the coke powder is less than 3 mm, and the particle size of the binder is less than 2 mm.

3. The method for preparing new blast furnace burden from sintered return fines according to claim 1, characterized in that, The uniformly mixing of the sintered return fine, the bituminous coal, the coke powder and the binder after the pretreatment to obtain the mixture comprises: The sintered return fine, the bituminous coal, the coke powder and the binder after the pretreatment are uniformly mixed by a strong mixer to obtain the mixture; The mass percentage of the sintered return fine in the mixture is 10-40%, the mass percentage of the bituminous coal is 55-80%, the mass percentage of the coke powder is 5-10%, and the mass percentage of the binder is 3-7%.

4. The method for preparing new blast furnace burden from sintered return fines according to claim 3, characterized in that, The binder is uniformly mixed with the coal powder and the sintered return fine in the form of solid particles, and the mass ratio is 3-7% of the total mass of the coal powder and the sintered return fine. The heating of the mixture and the preparation of the cold-pressed blank by a cold-pressing forming device comprise:

5. The method for preparing new blast furnace burden from sintered return fines according to claim 1, characterized in that, The mixture is heated by a mixture heating device, and the heating temperature is 70-90 DEG C; The mixture after the heating is cold-pressed by a cold-pressing forming device to prepare the cold-pressed blank; and the forming pressure is 3-7 t / cm. In the carbonization treatment, the gas is high-temperature waste gas generated after the combustion of mixed gas of coke oven gas and blast furnace gas.

6. The method for preparing new blast furnace burden from sintered return fines according to claim 1, characterized in that, In the cooling to room temperature by the gas cooling mode, the gas is inert gas.

7. The method for preparing new blast furnace burden from sintered return fines according to claim 1, characterized in that, ​

Images