Sintering iron-containing mixed ore containing silk road powder instead of part of FMG mixed powder and preparation method

Abstract

The application provides a sintering iron-containing mixed ore containing a silk road powder instead of part of FMG mixed powder and a preparation method. By selecting a silk road powder with a proper proportion, the use amount of the FMG mixed powder is greatly reduced, the proportion of the particle size less than 10 mm in the finished product particle size is reduced, the quality indexes such as the low-temperature reduction pulverization index RDI and the drum strength of the sintered ore are improved, the stability and smooth operation of the blast furnace production are ensured, and the ore matching cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical sintering technology, and in particular to a sintering mixture using Silk Road powder as a substitute for FMG mixed powder, its sintering method, and sintered ore. Background Technology

[0002] FMG (ferrous ore) blend powder has a grade of around 58%, is composed of limonite, and has generally poor sintering performance. It is an important component of iron-containing ore in sintering blends. In the steel industry, to reduce costs, lower-priced iron ore powder is often used to replace some of the higher-priced FMG blend powder. However, low-priced iron ore powder often has high levels of impurities such as sulfur (S) and phosphorus (P), and low levels of ferric sulfate (TFe) and SiO2 (SiO2). Using it in large proportions can lead to low sinter yield, decreased productivity, an excessive proportion of particles smaller than 10mm in the finished ore, and deterioration of properties such as the low-temperature reduction pulverization index (RDI) and drum strength of the sinter. These factors affect the effectiveness of the sinter and limit its application, thus preventing a truly effective reduction in blending costs. Summary of the Invention

[0003] To address the shortcomings of the existing technologies, this invention provides a sintered ore prepared by replacing part of the FMG mixed powder with silk road powder and its preparation method. By selecting an appropriate proportion of silk road powder, this invention significantly reduces the amount of FMG mixed powder used, thereby reducing the proportion of particles smaller than 10mm in the finished ore without reducing the yield and productivity. This improves the quality indicators of the sintered ore, such as the low-temperature reduction pulverization index (RDI) and drum strength, ensuring stable and smooth blast furnace production, while also greatly reducing ore blending costs.

[0004] To achieve the above objectives, the specific technical solution of the present invention is as follows: In a first aspect, the present invention provides a sintering iron-containing blended ore for which Silk Road powder replaces part of FMG mixed powder, comprising the following raw materials by mass percentage: PB powder 18-23%, BRBF powder 12-15%, FMG mixed powder 15-20%, high-silica coarse ore 6-9%, Silk Road powder 5-10%, blast furnace return ore 10-14%, lump ore return powder 3.4%, directly supplied iron concentrate 4.5%, domestic iron concentrate 8%, secondary resources 3-5%, and a concentrate rate not exceeding 13%; wherein, the concentrate includes, but is not limited to, Daye low-grade concentrate and Chengchao concentrate; the secondary resources include, but are not limited to, at least one of ironmaking gas ash, iron oxide scale, dust removal ash, and steel slag magnetic separation powder.

[0005] The chemical composition of the iron-containing blended ore for sintering, by mass percentage, includes: TFe: 59.13%, SiO2: 5.58%, CaO: 2.18%, S≤0.145%, P≤0.090%, Cu≤0.013%, Al2O3≤2.232%, and average particle size: 5.267mm.

[0006] Secondly, the present invention provides a sintered ore in which Silk Road powder replaces part of the FMG mixed powder. By mass percentage, the raw materials include: 80-84% iron-containing mixed ore for sintering, flux (4.5-6.0% dolomite, 0.5-3.0% limestone, 5.0-7.5% quicklime) and 4.0-4.6% solid fuel.

[0007] Furthermore, the raw materials for the sintered ore also include return ore, the amount of which is 16-20% of the total mass of the blended ore, flux and solid fuel, i.e., externally distributed return ore.

[0008] Furthermore, the basicity of the sinter is 1.93±0.05%, the RDI is greater than 65%, and the proportion of discharged ore particles smaller than 10mm is controlled to be below 20%.

[0009] Further, the flux includes quicklime, limestone, and dolomite. The flux must meet the following conditions upon entry into the plant: (1) Limestone: CaO%≥51.5; SiO2%≤1.5; MgO%≥0.5; S%≤0.06; H2O%≤5.0; Particle size: ≤3.0mm (>3 mm not exceeding 10%); (2) Quicklime: CaO%≥83; SiO2%≤3.0; MgO%≤7.0; S%≤0.15; Activity (4mol / L 40±1℃, 10min)≥220; Particle size: ≤3mm (>3mm proportion not exceeding 10%); (3) Dolomite: MgO%≥19.0; SiO2%≤3.5; P%≤0.080; S%≤0.040; H2O%≤5.0; Particle size: ≤3.0mm (>3 mm proportion not exceeding 10%).

[0010] Furthermore, the solid fuel is a mixture of coke powder and alumina. The solid fuel selected for production in the workshop is a 1:1 mass ratio of coke powder and alumina. A two-stage open-circuit crushing process using a combination of double rollers and four rollers is employed, with 67-77% of the coke powder having a particle size less than 3mm and 63-73% of the alumina having a particle size less than 3mm.

[0011] Thirdly, the present invention provides a method for preparing sintered ore in which the Silk Road powder replaces part of the FMG mixed powder, comprising the following steps: (1) Ingredients: Prepare raw materials according to a specific ratio, including iron-containing raw materials, secondary resources, limestone, lightly calcined dolomite, quicklime, coke powder and return ore, etc. (2) Mixing and granulation: Mix the prepared raw materials with water, and then granulate them using a pelletizer. The moisture content is controlled at 6.6%~7.2%. The first mixing requires 13-15 t / h of water, the second mixing requires 2-3 t / h of water, the filling rate is 11.767%, and the granulation time is approximately 4 to 6 minutes. (3) Material Distribution and Ignition: First, select 10-20mm sintered ore as the base material, spreading it to a thickness of 70-80mm. Then, use a roller feeder and a nine-roller distributor to evenly distribute the material onto the trolley with the base material. Place the granulated mixture onto the sintering equipment and ignite it. Use pure coke gas for ignition; the calorific value of the gas is 9211 kJ·m³. -3 The ignition temperature is between 1050 and 1200℃, the ignition time is about 1 minute, and the holding time is about 1 to 2 minutes. (4) Sintering: After ignition, the mixture begins the sintering process, which is accompanied by ventilation. The sintering negative pressure is 18.5 kPa. (5) Cooling: The ore blocks after sintering need to be cooled to a suitable temperature, usually less than 120°C, in order to facilitate subsequent processing and use; (6) Screening: Three vibrating screens are used to screen the cooled sintered particles. The undersize material is used as sintered return ore, and the oversize material is used as sintered ore product.

[0012] Compared with the prior art, the advantages of the present invention are: This invention replaces part of the FMG mixed powder with silk powder containing no less than 58% TFe, no less than 4.5% SiO2, and a burn-off of no more than 8.9%. By controlling the proportion of silk powder, the SiO2 content of the blended ore is correspondingly increased. This helps to react with gangue components at lower temperatures and with less solid fuel consumption to generate more low-melting-point substances, resulting in sinter with appropriate melting degree, good reducibility, and good drum strength. Simultaneously, by stabilizing the moisture content of the blended ore, controlling the average particle size of the blended ore, and controlling the silicon content to no less than 5.22%, the sintering process is optimized, improving sinter quality, reducing energy consumption, thereby lowering production costs and increasing production efficiency. Ultimately, this invention can control RDI to over 70% and the proportion of finished ore particles smaller than 10mm to below 20%, significantly improving sinter quality and facilitating the smooth operation of the blast furnace smelting process. Detailed Implementation

[0013] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in detail. Unless otherwise specified, the methods of the present invention are conventional methods in the art. Example 1

[0014] A sintering iron-containing blended ore for which Silk Road powder replaces a portion of FMG blended powder, comprising, by mass percentage: 18-23% PB powder, 12-15% BRBF powder, 15-20% FMG blended powder, 6-9% high-silica coarse iron ore, 5%-10% Silk Road powder, 10-14% blast furnace return ore, 3.4% lump ore return powder, 4.5% directly supplied iron concentrate, 8% domestic iron concentrate, and 3-5% secondary resources, with a concentrate rate not exceeding 13%. The secondary resources include, but are not limited to, at least one of ironmaking gas ash, iron oxide scale, dust collector ash, and steel slag magnetic separation powder. The concentrate includes, but is not limited to, Daye low-grade concentrate and Chengchao concentrate.

[0015] Because FMG mixed powder is limonite, it has a high loss on ignition, a large shrinkage rate during sintering, and low self-consolidation strength. When a large amount is added, the ore stock is low, the strength of the sinter drum decreases, and the TFe grade of the mixed ore is low, resulting in high coal consumption during sintering, which seriously affects the quality of sinter and the cost of sintering process.

[0016] By selecting silk road powder with a Tfe content of not less than 58%, SiO2 of not less than 4.5%, and burn-off of less than 8.9%, the cost of sintering ore blending is reduced while SiO2 is appropriately increased. This allows the powder to generate more low-melting-point substances at lower temperatures and with less solid fuel consumption and gangue components, resulting in sintered ore with appropriate melting degree, good reducibility, and good drum strength.

[0017] Table 1: Data on Ore Blending Materials

[0018] Based on the above raw material ratios, the resulting blended ore achieves the following composition:

[0019] By adjusting the ratio of silk road powder to FMG mixed powder and the moisture content, the composition of the sintered homogenized ore is made to meet the targets in the table above. Furthermore, the moisture content of the homogenized ore is stabilized, the average particle size is controlled, and the silicon content is ensured to be no less than 5.22%. The silicon content of the homogenized ore directly affects the porosity, strength, and other physical properties of the sinter. Simultaneously, it influences the chemical reaction pathways during sintering, especially the reaction of iron oxides, determining the chemical composition and purity of the final product. The SiO2 content of this scheme helps optimize the sintering process, improve sinter quality, reduce energy consumption, thereby lowering production costs and increasing production efficiency.

[0020] Table 2: Proportioning Scheme FMG blended powder and Silk Road powder together comprise 25%, with other varieties formulated as follows:

[0021]

[0022] A sintering composition of an iron-containing homogenized ore for sintering, in which Silk Road powder replaces part of the FMG mixed powder.

[0023] By using silk road powder, the overall SiO2 content is increased accordingly. Other components in the sintering batch, such as flux (quicklime, dolomite, limestone), fuel (coke powder, coal powder), and return ore, also need to be tested and adjusted to increase the amount of liquid phase generated during the sintering process, which is conducive to further improving the final sintering yield and the strength index of the sinter drum.

[0024] Table 3: Mixture Proportioning

[0025] Note: The three schemes were formulated using the iron-containing blended ore group with 16% FMG mixed powder and 9% Silk Road powder from Table 2.

[0026] The increased proportion of Silk Road powder significantly increased the SiO2 content of the blended ore. Furthermore, this mineral exhibits strong hydrophilicity, low hardness, and a density of 2.7-4.3 t / m³. 3 It is non-magnetic and contains water of crystallization. The fuel ratio should be appropriately increased to maintain a certain sintering temperature. From the perspective of assimilation and liquid phase fluidity, the alkalinity should be appropriately reduced and the proportion of quicklime should be increased to ensure uniform mixing of ingredients, good wet compatibility, and high material temperature.

[0027] The flux used in this workshop consists of dolomite, limestone, and quicklime. The magnitude and fluctuation of alkalinity are affected by the content of CaO, MgO, SiO2, and Al2O3. The amount of CaO, MgO, SiO2, and Al2O3 is mainly determined by the flux ratio, and the flux is essential for strengthening sintering.

[0028] Flux entry conditions: (1) Limestone: CaO%≥51.5; SiO2%≤1.5; MgO%≥0.5; S%≤0.06; H2O%≤5.0; Particle size: ≤3.0mm (>3 mm not exceeding 10%); (2) Quicklime: CaO%≥83; SiO2%≤3.0; MgO%≤7.0; S%≤0.15; Activity (4mol / L40±1℃, 10min)≥220; Particle size: ≤3mm, >3mm proportion not exceeding 10%; (3) Dolomite: MgO%≥19.0; SiO2%≤3.5; P%≤0.080; S%≤0.040; H2O%≤5.0; Particle size: ≤3.0mm (>3 mm proportion not exceeding 10%). Dolomite, limestone, and quicklime are purchased directly from qualified particle size products. Dolomite and limestone are transported to the batching tank via conveyor belts, while quicklime is delivered directly to the batching tank via sealed tank trucks and then compressed into the ore bin via pipelines using compressed air.

[0029] The solid fuel used in the workshop is a 1:1 ratio of coke powder and alumina coal. The coke powder is transported from the plant's coking plant and blast furnace troughs to the sintering workshop as coke, while the alumina coal is purchased from Shanxi Jineng. A two-stage open-circuit crushing process using roller crushers and four roller crushers is employed. 67-77% of the coke powder and 63-73% of the alumina coal have a particle size less than 3mm. Pure coke oven gas is used as the fuel for sintering ignition.

[0030] The sintering machine used is 260m 2 For belt-type exhaust sintering machines, the basicity of sintered ore is controlled to 1.93±0.05%; RDI is greater than 65%; and the proportion of discharged ore particles smaller than 10mm is controlled to below 20%.

[0031] Table 4: Chemical composition of experimental sintered ore

[0032] Table 5: Particle size composition of discharged ore (including particles smaller than 5 mm)

[0033] Methods for preparing sintered ore include: 1. Raw Material Preparation: Prepare raw materials according to a specific ratio. These raw materials include iron-containing raw materials, secondary resources, limestone, lightly calcined dolomite, quicklime, coke powder, and recycled ore, etc. The proportion and composition of each raw material have a significant impact on the final quality of the sinter.

[0034] 2. Mixing and Granulation: Mix the prepared raw materials with water, and then granulate them using a pelletizer. The moisture content is controlled at 6.6%~7.2%. The water addition for the first mixing is 13-15 t / h, and for the second mixing is 2-3 t / h. The filling rate is 11.767%, and the granulation time is approximately 4 to 6 minutes.

[0035] 3. Material Distribution and Ignition: First, select 10-20mm sintered ore as the base material, spreading it to a thickness of 70-80mm. Then, use a roller feeder and a nine-roller distributor to evenly distribute the raw material onto the trolley with the base material, ensuring the particle size gradually increases from top to bottom. Place the granulated mixture onto the sintering equipment and ignite it. Use pure coke gas for ignition; the gas calorific value is 9211 kJ·m³. -3 The ignition temperature is between 1050 and 1200℃. To reduce the negative impact on the quality of sinter caused by a sharp drop in the surface sinter temperature, the ignition time is about 1 minute and the holding time is about 1 to 2 minutes.

[0036] 4. Sintering: After ignition, the mixture begins the sintering process, which is accompanied by ventilation. The sintering negative pressure is 18.5 kPa. During sintering, the powdered mineral particles in the material agglomerate to form a blocky structure.

[0037] 5. Cooling: After sintering, the ore blocks need to be cooled to a suitable temperature, usually less than 120°C, in order to facilitate subsequent processing and use.

[0038] 6. Screening: Three vibrating screens are used to screen the cooled sintered particles. The undersize material is used as sintered return ore, and the oversize material is used as sintered ore product.

[0039] By adopting methods such as increasing sintering temperature and fabric thickness, controlling lower wet and dry charge densities, using multi-stage negative pressure during ignition, sintering, and cooling, and adjusting vertical firing speed, the amount of liquid phase generated during sintering can be increased, allowing the liquid phase to fully solidify and inhibiting low-temperature reduction and pulverization of the sinter. This is beneficial for further improving the final sintering yield and the drum strength index of the sinter, enhancing the role of the RDI index of the sinter, and further improving productivity.

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A sintering iron-containing homogenized ore for which Silk Road powder replaces a portion of FMG mixed powder, characterized in that, By weight percentage, it includes the following raw materials: The composition includes PB powder 18-23%, BRBF powder 12-15%, FMG mixed powder 15-20%, high-silica coarse iron ore 6-9%, Silk Road powder 5-10%, blast furnace return ore 10-14%, lump ore return powder 3.4%, direct-supply iron concentrate 4.5%, domestic iron concentrate 8%, secondary resources 3-5%, and a concentrate rate not exceeding 13%. Among these, the concentrate includes, but is not limited to, Daye low-grade concentrate and Chengchao concentrate. The secondary resources include, but are not limited to, at least one of the following: ironmaking gas ash, iron oxide scale, dust collector ash, and steel slag magnetic separation powder.

2. The iron-containing homogenized ore for sintering, in which Silk Road powder replaces part of the FMG mixed powder, as described in claim 1, is characterized in that... The chemical composition of the iron-containing blended ore for sintering, by mass percentage, includes: TFe: 59.13%, SiO2: 5.58%, CaO: 2.18%, S≤0.145%, P≤0.090%, Cu≤0.013%, Al2O3≤2.232%, and average particle size: 5.267mm.

3. A method for preparing sintered ore using the iron-bearing blended ore described in claim 1, characterized in that, Raw materials include: Iron-containing blended ores, fluxes, and solid fuels.

4. The method according to claim 3, characterized in that, The flux includes quicklime, limestone and dolomite; the flux must meet the following conditions upon entry into the plant: (1) Limestone CaO%≥51.5; SiO2%≤1.5; MgO%≥0.5; S%≤0.06; H2O%≤5.0; Particle size:≤3.0mm (>3 mm not exceeding 10%); (2) Quicklime CaO%≥83; SiO2%≤3.0; MgO%≤7.0; S%≤0.15; Activity (4mol / L 40±1℃, 10min)≥220; Particle size:≤3mm (>3mm proportion not exceeding 10%); (3) Dolomite MgO%≥19.0; SiO2%≤3.5; P%≤0.080; S%≤0.040; H2O%≤5.0; Particle size:≤3.0mm (>3 mm proportion not exceeding 10%).

5. The method according to claim 3, characterized in that, The solid fuel is a mixture of coke powder and aliphatic coal, used in a 1:1 mass ratio, with 67-77% of the coke powder having a particle size of less than 3mm and 63-73% of the aliphatic coal having a particle size of less than 3mm.

6. The method according to claim 3, characterized in that, By mass percentage, the raw materials include: 80-84% iron-containing blended ore for sintering, 4.5-6.0% dolomite, 0.5-3.0% limestone, 5.0-7.5% quicklime, and 4.0-4.6% solid fuel.

7. The method according to claim 3, characterized in that, The raw materials for the sinter also include recycled ore, and the amount of recycled ore is 16-20% of the total mass of the blended ore, flux and solid fuel.

8. The method according to claim 3, characterized in that, The basicity of the sinter is 1.93±0.05%, the RDI is greater than 65%, and the proportion of discharged ore particles smaller than 10mm is controlled to be below 20%.

9. The method according to claim 3, characterized in that, Includes the following steps: (1) Mixing and granulation: Mix the prepared raw materials with water, and then granulate them through a pelletizer. The moisture content is controlled at 6.6%~7.2%. The first mixing requires 13-15t / h of water, the second mixing requires 2-3t / h of water, the filling rate is 11.767%, and the granulation time is 4 to 6 minutes. (2) Material feeding and ignition: First, select 10-20mm sintered ore as the base material, and spread it 70-80mm thick. Then, use a round roller feeder and a nine-roller material feeder to evenly feed the material on the trolley with the base material. Arrange the granulated mixture on the sintering equipment and ignite it. The ignition temperature is between 1050 and 1200℃, the ignition time is 1 minute, and the holding time is 1 to 2 minutes. (3) Sintering: After ignition, the mixture begins the sintering process, which is accompanied by ventilation. The sintering negative pressure is 18.5 kPa. (4) Cooling: The ore blocks after sintering need to be cooled to a suitable temperature, usually less than 120°C, in order to facilitate subsequent processing and use; (5) Screening: Three vibrating screens are used to screen the cooled sintered particles. The undersize material is used as sintered return ore, and the oversize material is used as sintered ore product.

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