Process for the preparation of a metallized sinter

Abstract

The application provides a preparation process method of metallized sintered ore, comprising the following steps: first step: preparing materials according to a set component formula, and forming a mixture, wherein the materials include iron concentrate, flux, binder, combustion improver, steel metallurgical solid waste and coal powder; second step: stirring the mixture with water to make it uniform, and controlling the water content to be 14+ / -2%; third step: placing the stirred mixture for aging for more than 48 hours, so that the materials with uneven moisture or insufficient stirring can reach uniform moisture through mutual penetration, and the physical properties of the materials are improved, so that the materials are convenient for extrusion molding; fourth step: using mechanical pressing to mold the aged mixture into molded ore brick blanks; and fifth step: stacking the qualified ore brick blanks on a kiln car, and placing the ore brick blanks on the kiln car for curing for 4 days+ / -1 day, so that the moisture is evaporated, the molded brick blanks are fully bonded and dense, and the strength of the ore bricks is enhanced. The application has low investment, simple equipment and strong applicability.

Description

Technical Field

[0001] This invention relates to the fields of metal smelting and metallurgical solid waste recycling, and specifically to a process for preparing metallized sintered ore. Background Technology

[0002] In modern steelmaking, blast furnace ironmaking is the preferred process for many smelting enterprises. Compared with other types of smelting processes, blast furnace ironmaking has significant advantages in terms of operability, output, labor productivity, and overall energy consumption. Therefore, blast furnace ironmaking occupies an important position in the steelmaking field.

[0003] Since the 1980s, high-basicity sinter has been the main raw material for blast furnace ironmaking in my country. In recent decades, iron-containing raw materials have accounted for nearly 70% of the cost of blast furnace ironmaking, and sinter accounts for more than 70% of the furnace charge and more than 10% of the energy consumption per ton of steel, making it the second largest energy consumer in steel production. Currently, the main process for sinter production is as follows: raw material preparation, primary mixing, secondary mixing, charging, sintering in a sintering machine, ring cooling, finished sinter, and blast furnace. This process has high requirements for the particle size of the raw materials, requiring a particle size of <5mm. The iron-containing raw materials need to be of high grade, with few impurities, good strength, and uniform particle size. At the same time, the investment, construction, and operating costs are high.

[0004] In summary, the existing technology has the following problems: the raw materials required for blast furnace ironmaking are small in particle size and high in grade, which leads to high costs for blast furnace ironmaking. Summary of the Invention

[0005] This invention provides a process for preparing metallized sintered ore to reduce production costs and improve economic efficiency for enterprises.

[0006] Therefore, this invention proposes a process for preparing metallized sintered ore, comprising the following steps:

[0007] Step 1: Prepare the iron concentrate, flux, binder, combustion aid, iron and steel metallurgical solid waste, coal powder, etc. according to the set composition formula to form a mixture;

[0008] Step 2: Add water and stir to mix the ingredients evenly, with the moisture content controlled at 14±2%;

[0009] Step 3: Let the mixed material stand for aging for more than 48 hours to allow the raw materials that are uneven in moisture or insufficiently mixed to achieve uniform moisture through mutual penetration, thereby improving the physical properties of the raw materials and making them easier to extrude and mold.

[0010] Step 4: Use mechanical pressing to press the aged mixture into shape to obtain shaped mineral brick blanks;

[0011] Step 5: Stack the pressed and qualified ore brick blanks onto the kiln car. Place the ore brick blanks on the kiln car and let them stand for 4 days ± 1 day to allow the moisture to evaporate, so that the formed brick blanks can fully bond and become dense, thereby enhancing the strength of the ore bricks.

[0012] Step 6: After curing, the brick blanks are transported by kiln cars into the tunnel kiln for drying and firing. The temperature of the tunnel kiln is controlled between 1000℃±100℃ during firing.

[0013] Step 7: After firing, the bricks are removed from the kiln. To prevent the reduced iron metal from being oxidized, the 600℃ brick blanks are cooled when they leave the tunnel brick kiln.

[0014] Step 8: The roasted ore brick blanks are sent to the crushing and screening production line for processing. After crushing, the sinter with a particle size greater than 40mm is returned to the crushing system for further crushing. The qualified ore with a particle size of 5-40mm is sent to the blast furnace as sinter. The ore with a particle size less than 5mm is returned to the raw material batching system.

[0015] Furthermore, the particle size of iron-containing raw materials, fluxes, and iron and steel metallurgical solid waste is <30mm.

[0016] Furthermore, the 600℃ ore brick blanks are water-cooled after exiting the tunnel brick kiln.

[0017] Furthermore, the 600°C ore brick blanks exit the tunnel brick kiln and enter a sealed cooling box where nitrogen gas is introduced for cooling.

[0018] Furthermore, the high-temperature zone from 800℃ to the highest kiln temperature, and then gradually cooled back to 800℃, is controlled to last for more than 16 hours.

[0019] Furthermore, a crushing and screening production line using a single-roll crusher or a jaw crusher is selected, with screen apertures of 40mm and 5mm respectively.

[0020] Furthermore, in the first step, the component formula is set as follows, calculated in percentages: TFe: 55.5±2; FeO: 8.5±1; MgO: 2.35±0.1; Al2O3<2.9; S<0.12; TiO2<0.5; Sintering basicity: 1.8±0.12.

[0021] This invention does not limit the raw materials used to iron ore powder; other iron-containing materials and metallurgical solid waste can also be used, thus expanding the range of raw material selection and reducing the requirements for raw material selection. Through pressing and molding, various raw materials can be used, resulting in strong raw material adaptability and reduced costs.

[0022] Furthermore, compared to sintering machines, this invention requires lower investment and simpler equipment. It is highly adaptable; basically, any type of building material brick kiln can be used with the addition of a crushing system. Moreover, while traditional sintering processes only use mineral powder smaller than 3mm, this invention can use mineral powder or raw materials of 5-10mm. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the working principle of the present invention. Detailed Implementation

[0024] To provide a clearer understanding of the technical features, objectives, and effects of this invention, the invention is now described.

[0025] This invention provides a process for preparing metallized sintered ore, such as... Figure 1 As shown, the process is as follows:

[0026] Step 1: Prepare the iron-containing raw materials (iron concentrate), flux, binder, combustion aid, iron and steel metallurgical solid waste (metallurgical coke powder, primary dust collector ash from steelmaking, blast furnace gas ash, etc.), and pulverized coal according to the analysis results. The technical requirements for the mixed raw materials are detailed in Table 1.

[0027] Table 1: Technical Requirements for Mixtures

[0028]

[0029] Note: Other components meet the quality standards for ore procurement. Iron-containing raw materials, fluxes, and steel solid waste with a particle size of <5mm are acceptable. This process is more suitable for materials with a wider range of particle sizes than traditional processes.

[0030] Step 2: Add water and stir until the mixture is evenly mixed. The moisture content should be controlled at 14±2%. The mixture should not produce dust during the stirring process and should not stick to the glue when poured.

[0031] Step 3: Let the mixed material stand for aging for more than 48 hours. The purpose is to loosen the raw material particles, disperse the mud, homogenize the moisture, dissolve free CaO and MgO, reduce the moisture on the surface of the particles to penetrate into the particles, and make the raw materials with uneven moisture or insufficient mixing achieve uniform moisture through mutual penetration, improve the physical properties of the raw materials, and facilitate extrusion molding.

[0032] Step 4: Mechanical pressing and molding. The mechanical pressing equipment used in this invention includes automatic brick presses and automatic hydraulic presses, etc.

[0033] Step 5: The automatic stacking machine stacks the qualified ore brick blanks onto the kiln car. The ore brick blanks are placed on the kiln car for static curing for 4 days ± 1 day. The purpose is to evaporate the moisture, allow the formed ore brick blanks to fully bond and become dense, and enhance the strength of the ore bricks.

[0034] Step 6: After curing, the brick blanks are transported by kiln cars into the tunnel kiln for drying and firing. The maximum temperature of the tunnel kiln is controlled between 1000℃±200℃. The firing process involves raising the temperature to 800℃, then gradually lowering it to the highest kiln temperature, and finally reducing the temperature back to 800℃. The high-temperature section is controlled for more than 16 hours.

[0035] Step 7: Removing the bricks from the kiln after firing. To prevent the reduced iron from oxidizing, the 600℃ brick blanks are either water-cooled after exiting the tunnel kiln, or placed in a sealed cooling box and cooled with nitrogen. Cooling is achieved using ambient temperature cooling water or ambient temperature nitrogen.

[0036] Step 8: After the brick blanks exit the kiln, they are sent to a crushing and screening production line for processing. A single-roll crusher or a jaw crusher can be selected for the crushing and screening production line, with screen apertures of 40mm and 5mm. Sinter larger than 40mm is returned to the crushing system for further crushing. The qualified ore particle size after crushing is 5-40mm. Qualified ore is sent to the blast furnace as sinter, while ore smaller than 5mm is returned to the raw material batching system.

[0037] Implementation 1: This invention uses iron concentrate (powder) as raw material, limestone, dolomite, quicklime, and lightly calcined coal as flux, and coke powder or coal powder as auxiliary materials. Specific raw and auxiliary materials are detailed in Table 2.

[0038] Table 2: High-Alkalinity Sinter Batching List

[0039]

[0040] Manufacturing Method: 1. According to the above, use a loader to load various raw and auxiliary materials into the corresponding silos. Mix the materials according to the batching list in Table 1 and put them into the mixer. Add water (the amount of water is linked to the amount of raw and auxiliary materials, and the water content is controlled at 8%-10%, with a maximum of 15%). After mixing, put the mixture into the aging chamber and age for more than 48 hours. Then, put it into mechanical pressing and molding. The mechanical pressing and molding pressure is maintained at 10-50 tons, and the pressure is held for 0.5-5 seconds. This invention can obtain the initial strength of sintered ore with different hardness by adjusting the pressing pressure. As the pressure increases, the hardness of the sintered ore also increases. This invention can adjust the density and strength of sintered ore blocks by changing the pressure to meet the requirements of blast furnace smelting. This application can obtain pellets or sintered ore of different shapes by changing the shape of the mechanical pressing mold to meet the needs of different production conditions. For example, it can be spherical or ellipsoidal, or blocks of various shapes.

[0041] 2. The formed products are transported to a curing site for 4 days of curing, then placed into a tunnel kiln for roasting. The tunnel kiln temperature is controlled at 1000℃ for roasting, then gradually increased to 800℃, and then gradually decreased back to 800℃ for at least 16 hours, for example, 17 hours. (As the roasting temperature increases, the strength of the sinter gradually increases. This is manifested in the gradual oxidation of Fe3O4 into Fe2O3 grains. After the Fe2O3 grains grow and recrystallize, they interconnect and solidify, thus improving the sintering strength. At the same time, the 1000℃ high temperature will reduce the zinc in the material to gaseous zinc (zinc's boiling point is 907℃). As the combustion flue gas rises, it condenses and re-oxidizes at a lower temperature (zinc's melting point is 419.53℃). The fine zinc oxide particles formed by re-oxidation adhere to the rising dust and flue gas and are carried out of the furnace.) Eliminating zinc from the materials reduces the impact of zinc in the product on blast furnace production. (High zinc content can form nodules in the blast furnace, causing suspended charge and disrupting smooth operation. Simultaneously, Zn reacts with the furnace gas at high temperatures to form Zn oxides or sulfides. Under certain conditions, these compounds can cause corrosion of metal components in the furnace top equipment, block the charging system, and affect the uniformity of the blast furnace charge distribution, thus impacting stable operation and smelting efficiency.) The oxidation time is controlled to over 16 hours to ensure sufficient Fe2O3 oxidation into crystals and maintain the strength of the sinter.

[0042] 3. After the brick blanks exit the kiln, they are sent to a crushing and screening production line for processing. A jaw crusher or a single-roll crusher screening production line can be selected, with a screen aperture of 4mm. Sintered ore larger than 40mm needs further crushing. The qualified ore particle size after crushing is 5-40mm. Qualified ore is sent to the blast furnace for smelting, while ore smaller than 5mm is returned to the raw material end for further batching.

[0043] 4. By using qualified metallized sintered ore in a blast furnace, the sintered ore produced by this invention and the sintered ore produced by traditional process were smelted in the blast furnace at a ratio of 1:1. The composition of the sintered ore is shown in Table 3. There was no significant fluctuation in blast furnace production.

[0044] Table 3. Analysis of sintered ore composition in Implementation Plan 1

[0045]

[0046] Note: This invention does not impose any special restrictions on the type of iron concentrate. For example, one or more types of iron concentrate can be used, such as domestic magnetite, hematite (red ore), siderite, limonite, hematite, imported ore powder (such as from Australia and Brazil), and iron and steel metallurgical solid waste (metallurgical coke powder, primary dust removal ash from steelmaking, blast furnace gas ash, etc.), to meet the needs of effective components in blast furnace smelting.

[0047] Implementation 2: This invention uses iron concentrate (powder) as raw material, limestone, dolomite, quicklime, and lightly calcined coal as flux, and coke powder or coal powder as auxiliary materials, as detailed in Table 4.

[0048] Table 4: High-Alkalinity Sinter Batching List

[0049]

[0050]

[0051] Manufacturing Method: 1. According to the above, use a loader to load various raw and auxiliary materials into the corresponding silos. Mix the materials according to the batching list in Table 1 and put them into the mixer. Add water (the amount of water is linked to the amount of raw and auxiliary materials, and the water content is controlled at 8%-10%, with a maximum of 15%). After mixing, put the mixture into the aging chamber and age for more than 48 hours. Then, put it into mechanical pressing and molding. The mechanical pressing and molding pressure is maintained at 10-50 tons, and the pressure is held for 0.5-5 seconds. This invention can obtain the initial strength of sintered ore with different hardness by adjusting the pressing pressure. As the pressure increases, the hardness of the sintered ore also increases. This invention can adjust the density and strength of sintered ore blocks by changing the pressure to meet the requirements of blast furnace smelting. This application can obtain pellets or sintered ore of different shapes by changing the shape of the mechanical pressing mold to meet the needs of different production conditions. For example, it can be spherical or ellipsoidal, or blocks of various shapes.

[0052] 2. The formed products are transported to the curing site for curing for 4 days, and then sent into the tunnel kiln for stacking and firing. The maximum temperature of the tunnel kiln is controlled at 1000℃ for firing, then the temperature is raised to 800℃, and then gradually reduced to the highest temperature of the kiln. The high temperature section time is controlled to be more than 16 hours.

[0053] 3. After the brick blanks exit the kiln, they are sent to a crushing and screening production line for processing. A jaw crusher or a single-roll crusher screening production line can be selected, with screen apertures of 40mm and 5mm. Sintered ore larger than 40mm needs further crushing. The qualified ore particle size after crushing is 5-40mm. Qualified ore is sent to the blast furnace for smelting, while ore smaller than 5mm is returned to the raw material end for further batching.

[0054] 4. By using qualified metallized sintered ore in a blast furnace, the sintered ore produced by this invention and the sintered ore produced by traditional process were smelted in the blast furnace at a ratio of 1:1. The composition of the sintered ore is shown in Table 5. There was no significant fluctuation in blast furnace production.

[0055] Table 5. Analysis of sintered ore composition in Implementation Plan 2

[0056]

[0057] Note: This invention does not impose any special restrictions on the type of iron concentrate. For example, one or more types of iron concentrate can be used, such as domestic magnetite, hematite (red ore), siderite, limonite, hematite, imported ore powder (such as from Australia and Brazil), and iron and steel metallurgical solid waste (metallurgical coke powder, primary dust removal ash from steelmaking, blast furnace gas ash, etc.), to meet the needs of effective components in blast furnace smelting.

[0058] Implementation 3: This invention uses iron concentrate (powder) as raw material, limestone, dolomite, quicklime, and lightly calcined coal as flux, and coke powder or coal powder as auxiliary materials, as detailed in Table 6.

[0059] Table 6: High-Alkalinity Sinter Batching List

[0060]

[0061] Manufacturing Method: 1. According to the above, use a loader to load various raw and auxiliary materials into the corresponding silos. Mix the materials according to the batching list in Table 1 and put them into the mixer. Add water (the amount of water is linked to the amount of raw and auxiliary materials, and the water content is controlled at 8%-10%, with a maximum of 15%). After mixing, put the mixture into the aging chamber and age for more than 48 hours. Then, put it into mechanical pressing and molding. The mechanical pressing and molding pressure is maintained at 10-50 tons, for example, 30 tons, and the holding pressure is 0.5-5 seconds, for example, 2 seconds. This invention can obtain the initial strength of sintered ore with different hardness by adjusting the pressing pressure. As the pressure increases, the hardness of the sintered ore also increases. This invention can adjust the density and strength of sintered ore blocks by changing the pressure to meet the requirements of blast furnace smelting. This application can obtain pellets or sintered ore of different shapes by changing the shape of the mechanical pressing mold to meet the needs of different production conditions. For example, it can be spherical or ellipsoidal, or blocks of various shapes.

[0062] 2. The formed products are transported to the curing site for curing for 4 days, and then sent into the tunnel kiln for stacking and firing. The maximum temperature of the tunnel kiln is controlled at 1000℃ for firing, then the temperature is raised to 800℃, and then gradually reduced to the highest temperature of the kiln. The high temperature section time is controlled to be more than 16 hours.

[0063] 3. After the brick blanks exit the kiln, they are sent to a crushing and screening production line for processing. A jaw crusher or a single-roll crusher screening production line can be selected, with screen apertures of 40mm and 5mm. Sintered ore larger than 40mm needs further crushing. The qualified ore particle size after crushing is 5-40mm. Qualified ore is sent to the blast furnace for smelting, while ore smaller than 5mm is returned to the raw material end for further batching.

[0064] 4. By using qualified metallized sintered ore in a blast furnace, the sintered ore produced by this invention and the sintered ore produced by traditional process were smelted in the blast furnace at a ratio of 1:1. The composition of the sintered ore is shown in Table 7. There was no significant fluctuation in blast furnace production.

[0065] Table 7. Composition analysis of sintered ore produced under Implementation Plan 3

[0066]

[0067] Note: This invention does not impose any special restrictions on the type of iron concentrate. For example, one or more types of iron concentrate can be used, such as domestic magnetite, hematite (red ore), siderite, limonite, hematite, imported ore powder (such as from Australia and Brazil), and iron and steel metallurgical solid waste (metallurgical coke powder, primary dust removal ash from steelmaking, blast furnace gas ash, etc.), to meet the needs of effective components in blast furnace smelting.

[0068] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the invention. The various components of the present invention can be combined with each other without conflict. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A process for preparing metallized sinter, characterized in that, The preparation process of the metallized sintered ore includes the following steps: Step 1: Prepare the iron concentrate, flux, binder, combustion aid, iron and steel metallurgical solid waste, coal powder, etc. according to the set composition formula to form a mixture; Step 2: Add water and stir to mix the ingredients evenly, with the moisture content controlled at 14±2%; Step 3: Let the mixed material stand for aging for more than 48 hours to allow the raw materials that are uneven in moisture or insufficiently mixed to achieve uniform moisture through mutual penetration, thereby improving the physical properties of the raw materials and making them easier to extrude and mold. Step 4: Use mechanical pressing to press the aged mixture into shape to obtain shaped mineral brick blanks; Step 5: Stack the pressed and qualified ore brick blanks onto the kiln car. Place the ore brick blanks on the kiln car and let them stand for 4 days ± 1 day to allow the moisture to evaporate, so that the formed brick blanks can fully bond and become dense, thereby enhancing the strength of the ore bricks. Step 6: After curing, the brick blanks are transported by kiln cars into the tunnel kiln for drying and firing. The maximum temperature of the tunnel kiln is controlled between 1000℃±200℃. Step 7: After firing, the bricks are removed from the kiln. To prevent the reduced iron metal from being oxidized, the 600℃ brick blanks are cooled when they leave the tunnel brick kiln. Step 8: The roasted ore brick blanks are sent to the crushing and screening production line for processing. After crushing, the sinter with a particle size greater than 40mm is returned to the crushing system for further crushing. The qualified ore with a particle size of 5-40mm is sent to the blast furnace as sinter. The ore with a particle size less than 5mm is returned to the raw material batching system.

2. The preparation process of metallized sinter as described in claim 1, characterized in that, Iron-containing raw materials, fluxes, and solid waste from iron and steel metallurgy have a particle size of <30mm.

3. The preparation process of metallized sinter as described in claim 1, characterized in that, The ore brick blanks, heated to 600℃, are water-cooled after exiting the tunnel brick kiln.

4. The preparation process of metallized sinter as described in claim 1, characterized in that, The 600℃ ore brick blanks are taken out of the tunnel brick kiln and enter a sealed cooling box where nitrogen is purged for cooling.

5. The preparation process of metallized sinter as described in claim 1, characterized in that, The time spent in the high-temperature zone, from raising the temperature to 800℃ to the highest kiln temperature and then gradually lowering it back to 800℃, should be controlled to be more than 16 hours.

6. The preparation process of metallized sinter as described in claim 1, characterized in that, Choose a crushing and screening production line with a single roll crusher or a jaw crusher, with screen apertures of 40mm and 5mm respectively.

7. The preparation process of metallized sinter as described in claim 1, characterized in that, In the first step, the ingredient formula is set, calculated as a percentage: TFe: 55.5±2; FeO: 8.5±1; MgO: 2.35±0.1; Al2O3<2.9; S<0.12; TiO2<0.5; Sintering basicity: 1.8±0.12.

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