Method for increasing the proportion of low-reducing lump ore used in an ironmaking system

Abstract

This invention relates to a method for increasing the proportion of low-reducing lump ore used in ironmaking systems, belonging to the field of ironmaking sintering technology. To address the problem of low usage of low-reducing lump ore in ironmaking systems, this invention provides a method for increasing the proportion of low-reducing lump ore used in ironmaking systems. Specific steps include screening and crushing, batching, mixing and granulation, charging and ignition, sintering and cooling, and blast furnace application. This invention ensures that the mass percentage of low-reducing lump ore with a particle size of less than 0.5 mm and greater than 3 mm in the sintering material is less than 40%, thus simultaneously improving the reducibility of the lump ore and controlling the powder-to-core ratio during sintering, achieving a low-reducing lump ore usage ratio in the blast furnace of 300 kg / t to 1100 kg / t. This invention achieves good results in cost reduction and improved blast furnace smelting performance by increasing the usage of low-reducing lump ore.

Description

Technical Field

[0001] This invention belongs to the field of ironmaking sintering technology, and particularly relates to a method for increasing the proportion of low-reducible lump ore used in ironmaking systems. Background Technology

[0002] Continuous cost reduction in the ironmaking system is key to improving the efficiency of steel enterprises. In recent years, with relatively low lump ore premiums, the scientific and rational addition of lump ore to the blast furnace can significantly reduce the blast furnace coke ratio, alleviate the economic and environmental burden of the ironmaking process, and is of great significance for reducing the cost of the steel industry and achieving energy conservation and emission reduction.

[0003] Lump ore is one of the important iron-containing raw materials used in blast furnaces and an important component of a rational blast furnace burden. Its chemical composition and metallurgical properties directly affect the smooth operation of the blast furnace. Due to factors such as the moisture content and cracking rate of lump ore, the proportion of lump ore charged into the furnace is only 5-10%, which restricts the maximization of economic and social benefits.

[0004] Another important factor influencing the proportion of lump ore used in blast furnaces is its reducibility. The reducibility of lump ore significantly affects the reduction rate of sinter, improving blast furnace gas utilization and thus impacting the technical and economic indicators of blast furnace smelting. Under the same reduction conditions, the better the reducibility of the lump ore, the higher its reduction rate, which helps blast furnaces develop indirect reduction, improve gas utilization, reduce coke ratio, and increase output. This leads to a more limited proportion of lump ore with lower reducibility used in blast furnaces, generally less than 3%. Therefore, increasing the proportion of low-reducibility lump ore used in ironmaking systems is a pressing issue that needs to be addressed in this field. Summary of the Invention

[0005] To address the problem of the low proportion of low-reducing lump ore used in ironmaking systems, this invention provides a method for increasing the proportion of low-reducing lump ore used in ironmaking systems.

[0006] The technical solution of the present invention:

[0007] A method for increasing the proportion of low-reducible lump ore used in an ironmaking system includes the following steps:

[0008] Step 1: Screening and Crushing

[0009] Low-reducibility lump ore is screened to a particle size of 5mm to 10mm. The undersize material is collected as material A for later use. The oversize material is collected and divided into material B and material C. Material B is used as lump ore for blast furnace use. Material C is crushed to a particle size of less than 5mm and used as material D for later use.

[0010] Step 2, Ingredients:

[0011] Material A and material D are mixed to obtain low-reducing lump ore for sintering. During the mixing process, the particle size of the low-reducing lump ore is controlled so that the mass percentage of low-reducing lump ore with a particle size of less than 0.5 mm and low-reducing lump ore with a particle size of more than 3 mm in the low-reducing lump ore for sintering is less than 40%, and the remainder is low-reducing lump ore with a particle size of 0.5 mm to 3 mm.

[0012] A sintering mixture is prepared by mixing 10-80 parts by weight of low-reducible lump ore for sintering, 10-70 parts of iron ore powder, 5 parts of iron-containing solid waste, 3-4 parts of fuel and 8-12 parts of flux.

[0013] Step 3: Mixing and granulation:

[0014] The obtained sintered mixture is fed into a primary cylindrical mixer, water is added to wet the sintered mixture and it is mixed evenly. The evenly mixed sintered mixture is then fed into a secondary cylindrical mixer for granulation to obtain sintered particles.

[0015] Step 4: Ignite the fabric:

[0016] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer of a certain thickness. The sintering machine is ignited and the ignition temperature, ignition time and ignition negative pressure of the sintering machine are controlled.

[0017] Step 5: Sintering and Cooling

[0018] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan and the sintering negative pressure is controlled. After sintering, the sintered ore is cooled by an annular cooler and the sintered ore with a particle size of 3mm to 5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0019] Step Six: Blast Furnace Operation

[0020] The blast furnace iron charge used in blast furnace smelting includes material B obtained in step one, finished sinter and pellets obtained in step five. Material B accounts for 2% to 10% of the blast furnace iron charge by mass, finished sinter accounts for 60% to 85% of the blast furnace iron charge by mass, and the remainder is pellets.

[0021] Furthermore, the iron ore powder mentioned in step two includes one or a combination of domestic iron concentrate, imported iron ore powder, or blast furnace return ore powder; the iron-containing solid waste includes one or a combination of dust removal ash, dust removal sludge, steel slag, and iron oxide scale.

[0022] Furthermore, the fuel mentioned in step two is one or both of coke powder and anthracite; the flux is one or a combination of limestone powder, dolomite powder or active lime powder.

[0023] Furthermore, in step two, the basicity of the sintered mixture (CaO / SiO2) is controlled to be 1.7–2.3, the TFe content to be 54%–58%, the MgO content to be 1.5%–2.5%, the Al2O3 content to be 1.5%–2.3%, and the FeO content to be 7%–10%.

[0024] Furthermore, the water content of the sintering mixture in step three is controlled at 6% to 8%; the granulation time is 2 min to 5 min.

[0025] Furthermore, in step three, sintered particles with a particle size of 3 mm or larger account for 60% to 80% of the total mass of sintered particles.

[0026] Furthermore, the thickness of the sintered material layer described in step four is 500mm to 900mm.

[0027] Furthermore, the ignition temperature of the sintering machine described in step four is 1000℃~1100℃, the ignition time is 1min~3min, and the ignition negative pressure is 6000Pa~10000Pa.

[0028] Furthermore, the sintering negative pressure in step five is 9000Pa to 17000Pa, and the cooling is to cool the sintered ore to below 150°C.

[0029] Furthermore, in step six, the pellets with a particle size of 8mm to 16mm account for more than 85% of the total mass of the pellets, and the average particle size of the finished sinter is 20mm to 25mm, of which the finished sinter with a particle size of 5mm to 10mm accounts for less than 23% of the total mass of the finished sinter.

[0030] The beneficial effects of this invention are:

[0031] The present invention provides a method for increasing the proportion of low-reducing lump ore used in ironmaking systems. The low-reducing lump ore is screened, crushed and its particle size is controlled before being sintered to form sintered ore, which is then supplied to the blast furnace, so that the proportion of low-reducing lump ore used in the blast furnace reaches 300 kg / t to 1100 kg / t.

[0032] The present invention controls the particle size of low-reducible lump ore for sintering by ensuring that the mass percentage of low-reducible lump ore with a particle size of less than 0.5 mm and greater than 3 mm in the low-reducible lump ore material for sintering is less than 40%. This achieves both the effect of improving the reducibility of the lump ore and controlling the powder-to-core ratio during the sintering process. The resulting sinter has a suitable and uniform particle size, less powder, high mechanical strength, and good softening and dripping properties.

[0033] This invention solves the problem of the low proportion of low-reducing lump ore used in ironmaking systems. By increasing the amount of low-reducing lump ore used, it achieves good results in cost reduction and blast furnace smelting performance. Attached Figure Description

[0034] Figure 1 Photograph of the sinter prepared in Example 1. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0036] Example 1

[0037] This embodiment provides a method for increasing the proportion of low-reducible lump ore used in an ironmaking system, including the following steps:

[0038] Step 1: Screening and Crushing

[0039] The low-reducibility lump ore is first screened in the material yard with a particle size of 5mm. The undersize material is collected as material A for later use, and the oversize material is divided into material B and material C. Material B is used as lump ore for blast furnace use, and material C is crushed to a particle size of less than 5mm as material D for later use.

[0040] Step 2, Ingredients:

[0041] Material A and material D are mixed to obtain low-reducing lumpy ore for sintering. During the mixing process, the particle size of the low-reducing lumpy ore in the sintering low-reducing lumpy ore is controlled so that the mass percentage of low-reducing lumpy ore with a particle size of less than 0.5 mm is 20%, the mass percentage of low-reducing lumpy ore with a particle size of 3 mm to 5 mm is 16%, and the mass percentage of low-reducing lumpy ore with a particle size of 0.5 mm to 3 mm is 64%.

[0042] Ingredients shall be prepared in the following proportions by weight:

[0043] The sintering material consists of 15 parts of low-reducing lumpy ore, 66.2 parts of iron ore powder, 5 parts of iron-containing solid waste, 3.8 parts of fuel, and 10 parts of flux.

[0044] In this embodiment, the iron ore powder includes 16.2 parts of domestic iron concentrate, 30 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. In this embodiment, the iron-containing solid waste is a composition of dust removal ash, dust removal sludge, steel slag, and iron oxide scale mixed in any proportion.

[0045] In this embodiment, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, wherein coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this embodiment is limestone powder, wherein limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0046] In order to balance improving the reducibility of the lump ore and controlling the powder-to-core ratio during the sintering process, this embodiment controls the basicity of the sintering mixture (CaO / SiO2) to be 1.7, the TFe content to be 57%, the MgO content to be 2.0%, the Al2O3 content to be 1.7%, and the FeO content to be 9.0%.

[0047] Step 3: Mixing and granulation:

[0048] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0049] Step 4: Ignite the fabric:

[0050] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0051] Step 5: Sintering and Cooling

[0052] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0053] Step Six: Blast Furnace Operation

[0054] The blast furnace iron charge used in blast furnace smelting includes material B obtained in step one, finished sinter and pellets obtained in step five. Material B accounts for 6% of the blast furnace iron charge by mass, finished sinter accounts for 80% of the blast furnace iron charge by mass, and the remainder is pellets (14%).

[0055] In this embodiment, pellets with a particle size of 8mm to 16mm account for more than 85% of the total mass of pellets, and the average particle size of the finished sinter is 20mm to 25mm, of which finished sinter with a particle size of 5mm to 10mm accounts for less than 23% of the total mass of finished sinter.

[0056] In this embodiment, most of the lump ore is screened, crushed and particle size controlled to form sintered ore before being fed to the blast furnace. The proportion of the low-reducibility lump ore used in the blast furnace reaches 350 kg / t.

[0057] The low-reducibility lump ore raw material used in this embodiment has an outstanding cost-performance ratio. Although its reducibility is only 40%, making it difficult to add in large proportions in the blast furnace, through appropriate screening, crushing and particle size control, it is fully oxidized during the sintering process, and the reducibility of the sintered ore is finally raised to 80%, reducing the negative impact on the blast furnace.

[0058] Example 2

[0059] This embodiment provides a method for increasing the proportion of low-reducible lump ore used in an ironmaking system, including the following steps:

[0060] Step 1: Screening and Crushing

[0061] The low-reducibility lump ore is first screened in the material yard with a particle size of 5mm. The undersize material is collected as material A for later use, and the oversize material is divided into material B and material C. Material B is used as lump ore for blast furnace use, and material C is crushed to a particle size of less than 5mm as material D for later use.

[0062] Step 2, Ingredients:

[0063] Material A and material D are mixed to obtain low-reducing lumpy ore for sintering. During the mixing process, the particle size of the low-reducing lumpy ore in the sintering low-reducing lumpy ore is controlled so that the mass percentage of low-reducing lumpy ore with a particle size of less than 0.5 mm is 40%, the mass percentage of low-reducing lumpy ore with a particle size of 3 mm to 5 mm is 12%, and the mass percentage of low-reducing lumpy ore with a particle size of 0.5 mm to 3 mm is 48%.

[0064] Ingredients shall be prepared in the following proportions by weight:

[0065] The sintering material consists of 15 parts of low-reducing lumpy ore, 66.2 parts of iron ore powder, 5 parts of iron-containing solid waste, 3.8 parts of fuel, and 10 parts of flux.

[0066] In this embodiment, the iron ore powder includes 16.2 parts of domestic iron concentrate, 30 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. In this embodiment, the iron-containing solid waste is a composition of dust removal ash, dust removal sludge, steel slag, and iron oxide scale mixed in any proportion.

[0067] In this embodiment, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, wherein coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this embodiment is limestone powder, wherein limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0068] In order to balance improving the reducibility of the lump ore and controlling the powder-to-core ratio during sintering, this embodiment controls the basicity of the sintering mixture (CaO / SiO2) to be 1.75, the TFe content to be 56.7%, the MgO content to be 2.0%, the Al2O3 content to be 1.72%, and the FeO content to be 8.8%.

[0069] Step 3: Mixing and granulation:

[0070] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0071] Step 4: Ignite the fabric:

[0072] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0073] Step 5: Sintering and Cooling

[0074] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0075] Step Six: Blast Furnace Operation

[0076] The blast furnace iron charge used in blast furnace smelting includes material B obtained in step one, finished sinter and pellets obtained in step five. Material B accounts for 5% of the blast furnace iron charge by mass, finished sinter accounts for 79% of the blast furnace iron charge by mass, and the remainder is pellets (16%).

[0077] In this embodiment, pellets with a particle size of 8mm to 16mm account for more than 85% of the total mass of pellets, and the average particle size of the finished sinter is 20mm to 25mm, of which finished sinter with a particle size of 5mm to 10mm accounts for less than 23% of the total mass of finished sinter.

[0078] In this embodiment, most of the lump ore is screened, crushed and particle size controlled to form sinter before being fed to the blast furnace. The proportion of the low-reducibility lump ore used in the blast furnace reaches 313 kg / t.

[0079] Example 3

[0080] This embodiment provides a method for increasing the proportion of low-reducible lump ore used in an ironmaking system, including the following steps:

[0081] Step 1: Screening and Crushing

[0082] The low-reducibility lump ore is first screened in the material yard with a particle size of 5mm. The undersize material is collected as material A for later use, and the oversize material is divided into material B and material C. Material B is used as lump ore for blast furnace use, and material C is crushed to a particle size of less than 5mm as material D for later use.

[0083] Step 2, Ingredients:

[0084] Material A and material D are mixed to obtain low-reducing lumpy ore for sintering. During the mixing process, the particle size of the low-reducing lumpy ore in the sintering low-reducing lumpy ore is controlled so that the mass percentage of low-reducing lumpy ore with a particle size of less than 0.5 mm is 60%, the mass percentage of low-reducing lumpy ore with a particle size of 3 mm to 5 mm is 8%, and the mass percentage of low-reducing lumpy ore with a particle size of 0.5 mm to 3 mm is 32%.

[0085] Ingredients shall be prepared in the following proportions by weight:

[0086] The sintering material consists of 20 parts of low-reducing lumpy ore, 64.2 parts of iron ore powder, 5 parts of iron-containing solid waste, 3.8 parts of fuel, and 12 parts of flux.

[0087] In this embodiment, the iron ore powder includes 24.2 parts of domestic iron concentrate, 20 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. In this embodiment, the solid waste containing iron is a composition of dust removal ash, dust removal sludge, steel slag, and iron oxide scale mixed in any proportion.

[0088] In this embodiment, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, wherein coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this embodiment is limestone powder, wherein limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0089] In order to balance improving the reducibility of the lump ore and controlling the powder-to-core ratio during the sintering process, this embodiment controls the basicity of the sintering mixture (CaO / SiO2) to be 1.85, the TFe content to be 56.5%, the MgO content to be 2.0%, the Al2O3 content to be 1.7%, and the FeO content to be 8.8%.

[0090] Step 3: Mixing and granulation:

[0091] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0092] Step 4: Ignite the fabric:

[0093] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0094] Step 5: Sintering and Cooling

[0095] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0096] Step Six: Blast Furnace Operation

[0097] The blast furnace iron charge used in blast furnace smelting includes material B obtained in step one, finished sinter and pellets obtained in step five. Material B accounts for 8% of the blast furnace iron charge by mass, finished sinter accounts for 74% of the blast furnace iron charge by mass, and the remainder is pellets (18%).

[0098] In this embodiment, pellets with a particle size of 8mm to 16mm account for more than 85% of the total mass of pellets, and the average particle size of the finished sinter is 20mm to 25mm, of which finished sinter with a particle size of 5mm to 10mm accounts for less than 23% of the total mass of finished sinter.

[0099] In this embodiment, most of the lump ore is screened, crushed and particle size controlled to form sinter before being fed to the blast furnace. The proportion of the low-reducibility lump ore used in the blast furnace reaches 433 kg / t.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing sintered ore without using low-reducible lump ore, comprising the following steps:

[0102] Step 1, Batching: Prepare the sintering mixture by batching the ingredients according to the following mass proportions:

[0103] 81 parts iron ore powder, 5 parts iron-containing solid waste, 4.0 parts fuel and 10 parts flux.

[0104] In this comparative example, the iron ore powder includes 31 parts of domestic iron concentrate, 30 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. The iron-containing solid waste in this comparative example is a mixture of dust collector ash, dust collector sludge, steel slag, and iron oxide scale in any proportion.

[0105] In this comparative example, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, of which coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this comparative example is limestone powder, of which limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0106] In order to control the powder-to-core ratio during the sintering process, the basicity of the sintering mixture in this comparative example is controlled to be 1.72 (CaO / SiO2), 57.5% (TFe content), 2.0% (MgO content), 1.7% (Al2O3 content), and 9.0% (FeO content).

[0107] Step 2: Mixing and granulation:

[0108] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0109] Step 3: Ignite the fabric:

[0110] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0111] Step 4: Sintering and Cooling

[0112] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0113] Comparative Example 2

[0114] This comparative example provides a method for increasing the proportion of low-reducible lump ore used in an ironmaking system, including the following steps:

[0115] Step 1: Screening and Crushing

[0116] The low-reducibility lump ore is first screened in the material yard with a particle size of 5mm. The undersize material is collected as material A for later use, and the oversize material is divided into material B and material C. Material B is used as lump ore for blast furnace use, and material C is crushed to a particle size of less than 5mm as material D for later use.

[0117] Step 2, Ingredients:

[0118] Material A and material D are mixed to obtain low-reducing lumpy ore for sintering. During the mixing process, the particle size of the low-reducing lumpy ore in the sintering low-reducing lumpy ore is controlled. The mass percentage of low-reducing lumpy ore with a particle size of 3mm to 5mm in the sintering low-reducing lumpy ore is 20%, and the mass percentage of low-reducing lumpy ore with a particle size of 0.5mm to 3mm in the sintering low-reducing lumpy ore is 80%.

[0119] Ingredients shall be prepared in the following proportions by weight:

[0120] The sintering material consists of 15 parts of low-reducing lumpy ore, 66.2 parts of iron ore powder, 5 parts of iron-containing solid waste, 3.8 parts of fuel, and 10 parts of flux.

[0121] In this comparative example, the iron ore powder includes 16.2 parts of domestic iron concentrate, 30 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. The iron-containing solid waste in this comparative example is a mixture of dust collector ash, dust collector sludge, steel slag, and iron oxide scale in any proportion.

[0122] In this comparative example, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, of which coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this comparative example is limestone powder, of which limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0123] In order to balance improving the reducibility of lump ore and controlling the powder-to-core ratio during sintering, the basicity of the sintering mixture in this comparative study is controlled at CaO / SiO2 to be 1.75, TFe content to be 56.8%, MgO content to be 2.0%, Al2O3 content to be 1.7%, and FeO content to be 8.8%.

[0124] Step 3: Mixing and granulation:

[0125] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0126] Step 4: Ignite the fabric:

[0127] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0128] Step 5: Sintering and Cooling

[0129] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0130] Comparative Example 3

[0131] This comparative example provides a method for increasing the proportion of low-reducible lump ore used in an ironmaking system, including the following steps:

[0132] Step 1: Screening and Crushing

[0133] The low-reducibility lump ore is first screened in the material yard with a particle size of 5mm. The undersize material is collected as material A for later use, and the oversize material is divided into material B and material C. Material B is used as lump ore for blast furnace use, and material C is crushed to a particle size of less than 5mm as material D for later use.

[0134] Step 2, Ingredients:

[0135] Material A and material D are mixed to obtain low-reducing lumpy ore for sintering. During the mixing process, the particle size of the low-reducing lumpy ore in the low-reducing lumpy ore for sintering is controlled so that the mass percentage of low-reducing lumpy ore with a particle size of less than 0.5 mm in the low-reducing lumpy ore for sintering is 100%.

[0136] Ingredients shall be prepared in the following proportions by weight:

[0137] The sintering material consists of 15 parts of low-reducing lumpy ore, 66.2 parts of iron ore powder, 5 parts of iron-containing solid waste, 3.8 parts of fuel, and 10 parts of flux.

[0138] In this comparative example, the iron ore powder includes 16.2 parts of domestic iron concentrate, 30 parts of imported iron ore powder, and 20 parts of blast furnace return ore powder. The iron-containing solid waste in this comparative example is a mixture of dust collector ash, dust collector sludge, steel slag, and iron oxide scale in any proportion.

[0139] In this comparative example, the fuel is coke powder with a particle size of 0.5 mm to 3 mm, of which coke powder with a particle size of less than 3 mm accounts for more than 75% of the total mass of coke powder. The flux used in this comparative example is limestone powder, of which limestone powder with a particle size of less than 3 mm accounts for more than 90% of the total mass of limestone powder.

[0140] In order to balance improving the reducibility of lump ore and controlling the powder-to-core ratio during sintering, the basicity of the sintering mixture in this comparative study is controlled at CaO / SiO2 to be 1.73, TFe content to be 56.8%, MgO content to be 2.0%, Al2O3 content to be 1.7%, and FeO content to be 9.0%.

[0141] Step 3: Mixing and granulation:

[0142] The obtained sintered mixture is fed into a primary cylindrical mixer, and water is added to moisten the sintered mixture. The water content of the sintered mixture is controlled at 7.5%. After mixing evenly, the sintered mixture is fed into a secondary cylindrical mixer for granulation for 4 minutes to obtain sintered particles. Among them, sintered particles with a particle size of 3 mm or more account for 65% of the total mass of sintered particles.

[0143] Step 4: Ignite the fabric:

[0144] The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 800 mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1050℃, the ignition time is 2 min, and the ignition negative pressure is 8000 Pa.

[0145] Step 5: Sintering and Cooling

[0146] After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 10000Pa. After sintering, the sintered ore is cooled to below 150℃ by an annular cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace.

[0147] The sintering parameters of the finished sintered ore obtained from Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0148] Table 1

[0149]

[0150] As can be seen from the data comparison in Table 1, compared with Comparative Example 1, the present invention, by controlling the particle size of low-reducing lump ore, after using 15% low-reducing lump ore in the low-reducing lump ore material for sintering, has no negative impact on the quality of the finished sinter supplied to the blast furnace, significantly reduces sintering costs, and also reduces fuel consumption from 4% to 3.8%.

Claims

1. A method for increasing the proportion of low-reducing lump ore used in an ironmaking system, characterized in that, Includes the following steps: Step 1: Screening and Crushing Low-reducibility lump ore is screened to a particle size of 5mm. The undersize material is collected as material A for later use. The oversize material is collected and divided into material B and material C. Material B is used as lump ore for blast furnace use. Material C is crushed to a particle size of less than 5mm and used as material D for later use. Step 2, Ingredients: Material A and material D are mixed to obtain low-reducing lump ore for sintering. During the mixing process, the particle size of the low-reducing lump ore is controlled so that the mass percentage of low-reducing lump ore with a particle size of less than 0.5 mm and low-reducing lump ore with a particle size of more than 3 mm in the low-reducing lump ore for sintering is less than 40%, and the remainder is low-reducing lump ore with a particle size of 0.5 mm to 3 mm. The sintering mixture is prepared by mixing 10-80 parts by weight of low-reducible lump ore for sintering, 10-70 parts of iron ore powder, 5 parts of iron-containing solid waste, 3-4 parts of fuel and 8-12 parts of flux. Step 3: Mixing and granulation: The obtained sintered mixture is fed into a primary cylindrical mixer, where water is added to moisten the sintered mixture and mix it evenly. The evenly mixed sintered mixture is then fed into a secondary cylindrical mixer for granulation to obtain sintered particles. Sintered particles with a particle size of 3 mm or larger account for 60% to 80% of the total mass of the sintered particles. Step 4: Ignite the fabric: The sintered particles obtained from granulation are evenly distributed on the sintering machine trolley to obtain a sintered material layer with a thickness of 500mm~900mm. The sintering machine is ignited and the ignition temperature of the sintering machine is controlled at 1000℃~1100℃, the ignition time is 1min~3min, and the ignition negative pressure is 6000Pa~10000Pa. Step 5: Sintering and Cooling After the sintering machine is ignited, the fuel in the raw materials is burned under the action of the exhaust fan, and the sintering negative pressure is controlled at 9000Pa~17000Pa. After sintering, the sintered ore is cooled by the ring cooler, and the sintered ore with a particle size of 3.5mm or larger is screened out as finished sintered ore for use in the blast furnace. Step Six: Blast Furnace Operation The blast furnace iron charge used in blast furnace smelting includes material B obtained in step one, finished sinter and pellets obtained in step five. Material B accounts for 2% to 10% of the blast furnace iron charge by mass, finished sinter accounts for 60% to 85% of the blast furnace iron charge by mass, and the remainder is pellets.

2. The method for increasing the proportion of low-reducing lump ore used in an ironmaking system according to claim 1, characterized in that, The iron ore powder mentioned in step two includes one or a combination of domestic iron concentrate, imported iron ore powder, or blast furnace return ore powder; the iron-containing solid waste includes one or a combination of dust removal ash, dust removal sludge, steel slag, and iron oxide scale.

3. A method for increasing the proportion of low-reducible lump ore used in an ironmaking system according to claim 1 or 2, characterized in that, The fuel mentioned in step two is one or both of coke powder and anthracite; the flux is one or a combination of limestone powder, dolomite powder or active lime powder.

4. The method for increasing the proportion of low-reducing lump ore used in an ironmaking system according to claim 3, characterized in that, Step 2: Control the basicity of the sintered mixture (CaO / SiO2) to be 1.7~2.3, the TFe content to be 54%~58%, the MgO content to be 1.5%~2.5%, the Al2O3 content to be 1.5%~2.3%, and the FeO content to be 7%~10%.

5. The method for increasing the proportion of low-reducing lump ore used in an ironmaking system according to claim 4, characterized in that, The water content of the sintering mixture in step three is controlled at 6%~8%; the granulation time is 2min~5min.

6. The method for increasing the proportion of low-reducing lump ore used in an ironmaking system according to claim 5, characterized in that, The cooling described in step five involves cooling the sintered ore to below 150°C.

7. The method for increasing the proportion of low-reducing lump ore used in an ironmaking system according to claim 6, characterized in that, In step six, pellets with a particle size of 8mm to 16mm account for more than 85% of the total mass of pellets, and the average particle size of the finished sinter is 20mm to 25mm, of which finished sinter with a particle size of 5mm to 10mm accounts for less than 23% of the total mass of finished sinter.

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