Preparation method of fine-particle sintered return ore cold-pressing block

Abstract

The invention provides a preparation method of a fine-particle sintered return mine cold-pressing block, and belongs to the field of blast furnace burden development. The method comprises the following steps: mixing a fine particle sintering return mine raw material with a composite binder to obtain a first mixture; adding water into the first mixture to obtain a second mixture; the second mixture is subjected to compression molding, and green pellets are obtained; the green pellets are dried and cured, and cold pressing blocks are obtained; wherein the composite binder is composed of an organic component and an inorganic component, the organic component comprises at least one of polyacrylamide, gelatin and phenolic resin, and the inorganic component comprises at least one of sodium metasilicate anhydrous and anhydrous potassium carbonate. By adopting the composite binder with a specific ratio and combining with an optimized preparation process of the fine-particle sintered return mine cold-pressing block, efficient utilization of the fine-particle sintered return mine is realized, and the cold-pressing block is stable in performance, meets the requirements of a blast furnace, has both environmental protection property and economical efficiency, and effectively solves the technical problem of traditional sintered return mine treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of blast furnace burden development, and particularly relates to a preparation method of fine-grained sintered return fines cold briquetting. BACKGROUND

[0002] In the field of steel metallurgy, cold briquetting as a new type of blast furnace burden has been applied in some areas and has shown certain advantages. In North America (such as U.S. Steel Corporation), cold briquetting containing gas ash, rolling steel skin and other components has been used in blast furnaces, and the amount of cold briquetting used in 2014 reached 34 kg / tHM; Russia uses hard pitch to replace coke to prepare related briquetting, and the replacement ratio is 0.7-1.2 kg / kg, and long-term use can form a silicon carbide shell to protect the hearth. At present, the existing cold briquetting product types are rich, including metallurgical dust and mud briquetting, carbon-containing composite briquetting, and non-traditional mine briquetting, compared with traditional furnace burden, its sintering is not required, energy consumption can be reduced by more than 50%, and CO2 emission is reduced by 30%-40%. From the development trend, 75% of the iron-containing raw materials of the blast furnace are sintered ore, and the sintering process has always been the main link of energy consumption, greenhouse gas and pollutant emission. The energy consumption of this process accounts for more than 10% of the total energy consumption of the steel enterprise, and there are problems of high energy consumption and serious pollution. At the same time, the accumulation of sintered return fines has a serious impact on the natural environment, and as a byproduct of the sintering process, its recycling demand has greatly increased, so the cold briquetting process as a new type of blast furnace burden has become the key to solving the above problems.

[0003] However, there are still some main problems in the application of cold briquetting. On the one hand, the cold briquetting has low room temperature strength and is easy to powder at high temperature reduction, which will affect the permeability of the blast furnace, although the cold briquetting can reduce solid waste pollution and reduce coke consumption and CO2 emission by replacing part of the iron ore powder with recycled iron-containing waste (such as dust and rolling steel skin); on the other hand, the binder is a limiting link for its development, the traditional cement binder will increase the amount of slag, the organic binder will increase the cost and may pollute the furnace gas, in addition, the dry dust removal system is sensitive to hydrogen content, and the single addition amount of cold briquetting needs to be controlled. In terms of technical demand, on the one hand, with the decrease of iron ore resource grade, cold briquetting becomes an effective means to utilize complex mineral resources; on the other hand, the sintering link accounts for about 15% of the ton iron cost, and cold briquetting can significantly reduce energy consumption and raw material cost. Based on the above development status, trend, existing problems and technical demand, the preparation method of fine-grained sintered return fines cold briquetting has important research significance and application value. SUMMARY

[0004] The present application provides a preparation method of fine-grained sintered return fines cold briquetting to provide a new preparation method of fine-grained sintered return fines cold briquetting.

[0005] This application provides a method for preparing fine-grained sintered return ore cold-pressed briquettes, the method comprising: Fine-grained sintered return ore raw material is mixed with a composite binder to obtain the first mixture; Water is added to the first mixture to obtain the second mixture; The second mixture is pressed into shape to obtain green pellets; and The green pellets are dried and cured to obtain cold-pressed blocks; The composite adhesive is composed of organic and inorganic components. The organic components include at least one of polyacrylamide, gelatin, and phenolic resin, and the inorganic components include at least one of anhydrous sodium metasilicate and anhydrous potassium carbonate. The mass of the composite binder is 5% to 8% of the mass of the fine-grained sintered return ore raw material.

[0006] Optionally, the particle size of the fine-grained sintered return ore raw material is <2mm.

[0007] Optionally, the composite adhesive is composed of sodium metasilicate with zero water and phenolic resin, wherein the mass ratio of sodium metasilicate with zero water to phenolic resin is 3:2.

[0008] Optionally, the composite adhesive is composed of sodium metasilicate with zero water and polyacrylamide, wherein the mass ratio of sodium metasilicate with zero water to polyacrylamide is 3:4.

[0009] Optionally, the composite adhesive is composed of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin, and anhydrous potassium carbonate, wherein the mass ratio of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin, and anhydrous potassium carbonate is 3:4:2:2:2.

[0010] Optionally, the composite adhesive is composed of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin, wherein the mass ratio of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin is 3:4:2:2.

[0011] Optionally, the composite adhesive is composed of sodium metasilicate with zero water and gelatin, wherein the mass ratio of sodium metasilicate with zero water to gelatin is 3:2.

[0012] Optionally, the water mass is 3% to 5% of the total mass of the first mixture.

[0013] Optionally, the pressing pressure is 9MPa to 12MPa, and the holding time is 4min to 6min.

[0014] Optionally, the cold-pressed block meets the following performance requirements: Cold compressive strength is 800N~3000N; The reduction performance is 70%–88%; The low-temperature reduction pulverization performance is 65%–75%; The droplet melting properties meet the following requirements: T10 is 1070℃~1080℃, T40 is 1180℃~1280℃, ΔTB is 110℃~200℃, Ts is 1240℃~1340℃, Td is 1500℃~1585℃, ΔT is 245℃~260℃, ΔPmax is 12kPa~25kPa, and S is 1700kPa•℃~2800kPa•℃.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for preparing cold-pressed briquettes of fine-grained sintered return ore. The method includes: mixing fine-grained sintered return ore raw materials with a composite binder to obtain a first mixture; adding water to the first mixture to obtain a second mixture; pressing the second mixture into green pellets; and drying and curing the green pellets to obtain cold-pressed briquettes. The composite binder is composed of organic and inorganic components. The organic component includes at least one of polyacrylamide, gelatin, and phenolic resin. The inorganic component includes at least one of anhydrous sodium metasilicate and anhydrous potassium carbonate. The mass of the composite binder is 5% to 8% of the mass of the fine-grained sintered return ore raw materials. On the one hand, this application utilizes fine-grained sintered return ore as a specific raw material, specifically as the base material for cold-pressed briquettes, thus opening up a new avenue for the resource utilization of such raw materials. On the other hand, it employs a composite binder system composed of organic and inorganic components. The organic components (polyacrylamide, gelatin, and phenolic resin) form a thin film encapsulating the particles, utilizing intermolecular forces to enhance the room-temperature compressive strength of the cold-pressed briquettes, solving the problem of insufficient room-temperature strength of single inorganic binders. The inorganic components (anhydrous sodium metasilicate and anhydrous potassium carbonate) form a stable framework at high temperatures through hydration reactions or mineral phase transformations, improving the high-temperature reduction stability of the cold-pressed briquettes and compensating for the high-temperature decomposition defects of organic binders. Therefore, a novel method for preparing fine-grained sintered return ore cold-pressed briquettes is provided. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart illustrating a method for preparing fine-grained sintered return ore cold-pressed blocks, as provided in an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1 to 6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "including" and "contains" as used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0021] Figure 1 This is a schematic flowchart illustrating a method for preparing fine-grained sintered return ore cold-pressed blocks, as provided in an embodiment of this application.

[0022] like Figure 1 As shown in the embodiment of this application, a method for preparing fine-grained sintered return ore cold-pressed briquettes is provided, the method comprising: S1. The fine-grained sintered return ore raw material is mixed with the composite binder to obtain the first mixture; In step S1 of this application, fine-grained sintered return ore is used as raw material to reduce accumulation pollution and reduce the cyclic load of the sintering process through secondary utilization; the organic components of the composite binder (such as polyacrylamide and gelatin) can enhance particle adhesion through intermolecular forces, while the inorganic components (such as sodium metasilicate with zero water) provide high-temperature stability. The two work together to improve the overall performance of the cold-pressed block.

[0023] In some embodiments, the particle size of the fine-grained sintered return ore is <2 mm.

[0024] Fine-grained raw materials (<2mm) have a large specific surface area, allowing for more thorough contact with the binder and improving bonding efficiency. At the same time, the dense packing of fine particles reduces porosity, which is beneficial for improving the density and strength of cold-pressed blocks.

[0025] In some embodiments, the particle size gradient of the fine-grained sintered return ore raw material includes: no screening, 1 mm to 2 mm, <2 mm, and <1 mm.

[0026] Particle size sieving (such as <1mm, 1mm~2mm grading) can optimize the molding performance of raw materials of different particle sizes, avoiding uneven molding or strength fluctuations caused by coarse particles.

[0027] In some embodiments, the composite adhesive is composed of organic and inorganic components, wherein the organic components include at least one of polyacrylamide, gelatin, and phenolic resin, and the inorganic components include at least one of anhydrous sodium metasilicate and anhydrous potassium carbonate.

[0028] In some embodiments, the mass of the composite binder is 5% to 8% of the mass of the fine-grained sintered return ore raw material.

[0029] In some embodiments, the composite adhesive is composed of sodium metasilicate with zero water and phenolic resin, wherein the mass ratio of sodium metasilicate with zero water to phenolic resin is 3:2.

[0030] In some embodiments, the composite adhesive is composed of sodium metasilicate with zero water and polyacrylamide, wherein the mass ratio of sodium metasilicate with zero water to polyacrylamide is 3:4.

[0031] In some embodiments, the composite adhesive is composed of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin, and anhydrous potassium carbonate, wherein the mass ratio of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin, and anhydrous potassium carbonate is 3:4:2:2:2.

[0032] In some embodiments, the composite adhesive is composed of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin, wherein the mass ratio of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin is 3:4:2:2.

[0033] In some embodiments, the composite adhesive is composed of sodium metasilicate with zero water and gelatin, wherein the mass ratio of sodium metasilicate with zero water to gelatin is 3:2.

[0034] Organic components (polyacrylamide, gelatin, and phenolic resin) form a thin film encapsulating particles, utilizing intermolecular forces to enhance the room-temperature compressive strength of the cold-pressed block, thus addressing the issue of insufficient room-temperature strength with a single inorganic binder. Inorganic components (anhydrous sodium metasilicate and anhydrous potassium carbonate) form a stable framework at high temperatures through hydration reactions or mineral phase transformations, improving the high-temperature reduction stability of the cold-pressed block (e.g., reducing the low-temperature reduction pulverization rate to 65%–75%), compensating for the high-temperature decomposition of organic binders. The specific ratio of organic to inorganic components is optimized through orthogonal experiments to balance their synergistic effects, ensuring that the cold-pressed block simultaneously meets both room-temperature strength and high-temperature metallurgical performance requirements.

[0035] The mass of the composite binder is limited to 5% to 8% of the mass of the fine-grained sintered return ore raw material. If it is too low, the binder will not be able to fully coat the particles, resulting in insufficient strength. If it is too high, it will increase the cost and may introduce too many impurities (such as potassium and sodium) that will affect the smooth operation of the blast furnace. The range of 5% to 8% can achieve a balance between strength and economy.

[0036] S2. Add water to the first mixture to obtain the second mixture; In some embodiments, the water mass is 3% to 5% of the total mass of the first mixture.

[0037] Water, as a medium, allows the binder to fully dissolve or disperse, promoting its uniform spreading on the surface of the recycled ore particles and enhancing the wettability between the binder and the particles. An appropriate amount of water (3%–5%) can improve the plasticity of the material, avoiding difficulties in molding due to excessive dryness or a decrease in strength due to excessive moisture, thus ensuring the stability of subsequent pressing and molding.

[0038] S3. Press the second mixture into shape to obtain green balls; In some embodiments, the pressing pressure is 9 MPa to 12 MPa, and the holding time is 4 min to 6 min.

[0039] By applying pressure (9MPa–12MPa) and holding time (4 min–6 min), material particles are brought into close contact, reducing porosity. The adhesive properties of the binder and the friction between particles then form green pellets with a specific shape and initial strength. Optimizing the pressure and holding time balances particle densification with energy consumption; excessive pressure leads to particle breakage, while insufficient pressure results in inadequate green pellet strength. Insufficient holding time prevents the binder from fully functioning, while excessive holding time reduces production efficiency.

[0040] S4. The green balls are dried and cured to obtain cold-pressed blocks.

[0041] In some embodiments, the drying and curing temperature is 105°C and the time is 24 hours.

[0042] Drying at 105℃ for 24 hours removes excess moisture, promotes the curing and shaping of the binder (especially organic binders), enhances the bonding force between particles, and improves the room temperature strength of the cold-pressed blocks (cold compressive strength 1500N~3000N). The drying process also avoids pulverization or cracking during high-temperature reduction caused by residual moisture, ensuring the stability of the cold-pressed blocks in subsequent metallurgical processes.

[0043] In some embodiments, the cold-pressed block satisfies the following properties: Cold compressive strength is 800N~3000N; The reduction performance is 70%–88%; The low-temperature reduction pulverization performance is 65%–75%; The droplet melting properties meet the following requirements: T10 is 1070℃~1080℃, T40 is 1180℃~1280℃, ΔTB is 110℃~200℃, Ts is 1240℃~1340℃, Td is 1500℃~1585℃, ΔT is 245℃~260℃, ΔPmax is 12kPa~25kPa, and S is 1700kPa•℃~2800kPa•℃.

[0044] It should be noted that the cold compressive strength (800N~3000N) can ensure that the cold-pressed blocks are not easily broken during transportation, storage and furnace loading, thus avoiding affecting the permeability of the blast furnace.

[0045] The reduction performance (70%–88%) can reflect the efficiency of cold-pressed briquettes being reduced in the blast furnace. When matched with sinter, it can ensure the smooth operation of the blast furnace and the output of molten iron.

[0046] Low-temperature reduction pulverization performance (65%–75%) can measure the resistance of cold-pressed briquettes to pulverization during low-temperature (400–600℃) reduction. If the index is too high, it will lead to a decrease in the permeability of the blast furnace charge column. 65%–75% can meet the requirements of blast furnace operation.

[0047] The T10 (1070–1080℃) and T40 (1180–1280℃) values ​​of the droplet properties reflect the temperatures at which the cold-pressed briquettes begin to soften and reach 40% softening. Matching these values ​​with the sintered ore can prevent premature or delayed softening in the blast furnace, which could lead to deterioration in permeability. ΔTB (110–200℃) and ΔT (245–260℃) represent the softening and dropleting ranges, respectively. Excessively wide ranges can increase the blast furnace coke ratio; controlling these ranges within the specified limits ensures efficient heat utilization within the furnace. ΔPmax (12–25 kPa) and S value (1700–2800 kPa•℃) reflect the maximum pressure difference and permeability index during the dropleting process. Reasonable values ​​can prevent abnormal situations such as blast furnace suspension and ensure smooth operation.

[0048] In summary, the method for preparing cold-pressed briquettes of fine-grained sintered return ore provided in this application, through the use of a composite binder with a specific ratio and an optimized preparation process, achieves efficient utilization of fine-grained sintered return ore. The resulting cold-pressed briquettes exhibit stable performance and are suitable for blast furnace requirements, combining environmental friendliness and economy, effectively solving the technical challenges of traditional sintered return ore processing. This application has the following advantages: (1) Advantages in raw material utilization and environmental protection: The efficient secondary utilization of fine-grained sintering return ore, using fine-grained sintering return ore with a particle size of <2mm as raw material, optimizes the molding performance through graded screening (such as 1mm~2mm, <1mm, etc.), which not only solves the pollution problem of traditional sintering return ore accumulation, but also reduces the cyclic re-firing load of the sintering process, reduces energy consumption and pollutant emissions, and conforms to the trend of low carbon and environmental protection. At the same time, the raw material has strong adaptability and can effectively process fine-grained return ore of different particle sizes without complicated pretreatment, thus broadening the scope of resource utilization of sintering return ore.

[0049] (2) Synergistic performance advantages of composite binders: The organic and inorganic components work synergistically. The composite binder is composed of organic components (polyacrylamide, gelatin, phenolic resin, etc.) and inorganic components (anhydrous sodium metasilicate, anhydrous potassium carbonate, etc.). The organic components enhance the room temperature strength of the cold-pressed block through intermolecular forces, while the inorganic components form a stable skeleton through high-temperature reaction to ensure high-temperature stability, overcoming the defects of single organic binders being easy to decompose at high temperatures and single inorganic binders having insufficient room temperature strength. At the same time, precise ratio optimization is achieved, and various specific ratios (such as 3:2, 3:4, 4:2:2:3:2, etc.) are specified. Through orthogonal experiments, the synergistic effect is balanced to ensure that the cold-pressed block simultaneously meets the requirements of room temperature cold compressive strength (800N~3000N) and high-temperature metallurgical performance (such as low-temperature reduction pulverization rate of 65%~75% and reduction performance of 70%~88%). In addition, the amount added is reasonable and controllable, with the binder accounting for 5% to 8% of the raw material mass. This ensures that the particles are fully coated to improve strength, while avoiding the excessive introduction of impurities such as potassium and sodium that may affect the smooth operation of the blast furnace, thus balancing performance and economy.

[0050] (3) Scientific and economic advantages of the preparation process: The process parameters are precisely optimized, and the amount of water added is controlled at 3% to 5% of the total mass of the first mixture to ensure uniform dispersion of the binder, improve the plasticity of the material, and ensure molding stability; the pressing pressure (9MPa to 12MPa) and holding time (4min to 6min) balance particle densification and energy consumption, avoiding particle breakage due to excessive pressure or affecting strength due to insufficient pressure; drying at 105℃ for 24h promotes the curing of the binder, removes excess moisture, avoids pulverization or cracking during high-temperature reduction, and improves the stability of cold-pressed blocks. At the same time, the process is simple and efficient, does not require high-temperature sintering, has simple equipment requirements, and consumes significantly less energy than traditional processes. It is easy to manage and mass-produce, reducing the cost per ton of iron.

[0051] (4) Advantages in product performance and compatibility with blast furnace: The overall performance meets the standards and is stable. The cold compressive strength, reduction performance, low-temperature reduction pulverization performance and dripping performance (parameters such as T10, T40, ΔTB, etc.) of the cold-pressed briquettes are all within a reasonable range that matches the sinter, and can directly replace part of the sinter in the furnace. At the same time, it can ensure the smooth operation of the blast furnace, and the dripping performance parameters (such as ΔPmax, S value) are reasonably controlled to avoid the deterioration of permeability or the problem of suspended material during high-temperature reduction. The low-temperature reduction pulverization rate is moderate, ensuring the stable permeability of the blast furnace charge column and making it highly compatible with the blast furnace smelting process.

[0052] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0053] Example 1 Raw material: 1000g of fine-grained sintered return ore with a particle size <2mm.

[0054] Composite binder: Sodium metasilicate with zero water and phenolic resin are used, with a mass ratio of 3:2 and a total mass of 5% (i.e. 50g) of the mass of fine-grained sintered return ore raw material.

[0055] This embodiment provides a method for preparing fine-grained sintered return ore cold-pressed blocks, comprising the following steps: S11. The fine-grained sintered return ore is mixed with the composite binder to obtain the first mixture; S21. Add water (approximately 31.5g) at 3% of the total mass of the first mixture and stir until homogeneous to obtain the second mixture; S31. Press the second mixture under a pressure of 9MPa and hold the pressure for 4 minutes to obtain green pellets; S41. Dry and cure the green pellets at 105℃ for 24 hours to obtain cold-pressed blocks.

[0056] Example 2 Raw material: 1000g of fine-grained sintered return ore with a particle size of 1mm to 2mm.

[0057] Composite binder: Sodium metasilicate with zero water and polyacrylamide are used in a mass ratio of 3:4, and the total mass is 6% (i.e. 60g) of the mass of fine-grained sintered return ore raw material.

[0058] This embodiment provides a method for preparing fine-grained sintered return ore cold-pressed blocks, comprising the following steps: S11. The fine-grained sintered return ore is mixed with the composite binder to obtain the first mixture; S21. Add water (approximately 42.4g) at 4% of the total mass of the first mixture and stir until homogeneous to obtain the second mixture; S31. Press the second mixture under a pressure of 10MPa and hold the pressure for 5 minutes to obtain green pellets; S41. Dry and cure the green pellets at 105℃ for 24 hours to obtain cold-pressed blocks.

[0059] Example 3 Raw material: 1000g of fine-grained sintered return ore with a particle size <1mm.

[0060] Composite binder: It consists of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin and anhydrous potassium carbonate, with a mass ratio of 3:4:2:2:2, and the total mass is 7% (i.e. 70g) of the mass of fine-grained sintered return ore raw material.

[0061] This embodiment provides a method for preparing fine-grained sintered return ore cold-pressed blocks, comprising the following steps: S11. The fine-grained sintered return ore is mixed with the composite binder to obtain the first mixture; S21. Add water (approximately 53.5g) at 5% of the total mass of the first mixture and stir until homogeneous to obtain the second mixture; S31. Press the second mixture under 11MPa pressure and hold for 5 minutes to obtain green pellets; S41. Dry and cure the green pellets at 105℃ for 24 hours to obtain cold-pressed blocks.

[0062] Example 4 Raw material: 1000g of unscreened fine-grained sintered return ore (particle size <2mm).

[0063] Composite binder: It consists of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin in a mass ratio of 3:4:2:2, and the total mass is 8% (i.e. 80g) of the mass of fine-grained sintered return ore raw material.

[0064] This embodiment provides a method for preparing fine-grained sintered return ore cold-pressed blocks, comprising the following steps: S11. The fine-grained sintered return ore is mixed with the composite binder to obtain the first mixture; S21. Add water (approximately 43.2g) at 4% of the total mass of the first mixture and stir until homogeneous to obtain the second mixture; S31. Press the second mixture under a pressure of 12MPa and hold the pressure for 6 minutes to obtain green pellets; S41. Dry and cure the green pellets at 105℃ for 24 hours to obtain cold-pressed blocks.

[0065] Example 5 Raw material: 1000g of fine-grained sintered return ore with a particle size <2mm.

[0066] Composite binder: Sodium metasilicate with zero water and gelatin are used, with a mass ratio of 3:2, and the total mass is 6% (i.e. 60g) of the mass of fine-grained sintered return ore raw material.

[0067] This embodiment provides a method for preparing fine-grained sintered return ore cold-pressed blocks, comprising the following steps: S11. The fine-grained sintered return ore is mixed with the composite binder to obtain the first mixture; S21. Add water (approximately 31.8g) at 3% of the total mass of the first mixture and stir until homogeneous to obtain the second mixture; S31. Press the second mixture under a pressure of 10MPa and hold the pressure for 4 minutes to obtain green pellets; S41. Dry and cure the green pellets at 105℃ for 24 hours to obtain cold-pressed blocks.

[0068] The cold-pressed blocks obtained in Examples 1-5 were subjected to performance testing, and the results are shown in Tables 1 and 2. The specific performance testing methods are as follows: Compressive strength: Refer to the national standard method (GB / T14201-2018). The compressive strength of the cold-pressed block is determined on a universal testing machine. The maximum pressure when the cold-pressed block is crushed is recorded. The pressure at this point is the compressive strength of the cold-pressed block. 10 blocks are measured in each group, and the arithmetic mean is taken (unit: N).

[0069] Reduction performance: Refer to the national standard method (GB / T13241-2017). A layer of high-alumina balls was placed at the bottom of a porous reduction tube, and a 500g cold-pressed block was placed on top of the high-alumina balls. The reduction tube was then placed in a reduction furnace. Under nitrogen protection, the temperature was increased to 900℃ at a rate of 10℃ / min. Reduction was carried out at 900℃ for 180min, during which a mixed gas of CO and N2 was introduced at a flow rate of 15L / min, with a CO:N2 ratio of 3:7, a CO flow rate of 4.5L / min, and a N2 flow rate of 10.5L / min. After reduction, the mixture was cooled under nitrogen protection. After the experiment was completed, the degree of reducibility of the pellets was calculated using the formula based on the initial sample weight, the initial ferrous and total ferric content in the sample, and the mass reduction during the reduction process.

[0070] Melting and dripping properties: The softening and melting characteristics of cold-pressed blocks were tested using a high-temperature load softening and melting test apparatus. The cold-pressed blocks were placed in a graphite crucible with three layers of furnace charge: the top and bottom layers contained 40g and 80g of coke, respectively, and the middle layer contained 500g of cold-pressed block. All samples had uniform particle size. Under N2 (5L / min) protection, the temperature was raised to 900℃, then switched to reducing gas (12L / min, 70% N2-30% CO) and the temperature was further increased to the dripping temperature. The experiment was stopped when the mass of the dripping material reached 20g, and the temperature was switched back to N2 protection at 2L / min to cool to room temperature. The dripping material was collected by the graphite at the bottom, and various softening and melting properties were automatically exported by the computer.

[0071] Low-temperature reduction pulverization performance: Take 500g of cold-pressed block, dry it, and place it in a heat-resistant stainless steel reaction tube. Under N2 protection, heat it to 500℃ (8℃ / min), then switch to reducing gas (15L / min) and maintain the temperature for 60min. The reducing gas composition is 20%CO-20%CO2-60%N2. After reduction, introduce N2, cool to room temperature, and weigh the total mass. Then pour it into a rotating drum, rotate it, and remove it. Use square holes of 0.5mm, 3.2mm, and 6.3mm to separate and weigh each part. Calculate the low-temperature reduction pulverization index according to the corresponding formula.

[0072] Table 1 shows the compressive strength, reduction properties, and low-temperature reduction pulverization properties of the cold-pressed blocks in Examples 1-5.

[0073] Table 2. Melting droplet properties of cold-pressed blocks in Examples 1-5

[0074] As shown in Tables 1 and 2, the cold-pressed blocks obtained in Examples 1 to 5 meet the following performance requirements: cold compressive strength of 800N to 3000N; reduction performance of 70% to 88%; low-temperature reduction and pulverization performance of 65% to 75%; and droplet properties of T10 of 1070℃ to 1080℃, T40 of 1180℃ to 1280℃, ΔTB of 110℃ to 200℃, Ts of 1240℃ to 1340℃, Td of 1500℃ to 1585℃, ΔT of 245℃ to 260℃, ΔPmax of 12kPa to 25kPa, and S value of 1700kPa•℃ to 2800kPa•℃.

[0075] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages: (1) By combining cold-pressed block preparation and metallurgical performance testing, the technical bottleneck of low utilization rate, high energy consumption and unstable metallurgical performance of traditional sintered return ore has been overcome. The technical solution is an innovation that is hard for technical personnel in the industry to predict, and significantly improves the feasibility of resource utilization of sintered return ore.

[0076] (2) It covers the key parameters of the entire process of cold-pressed block preparation (binder ratio, molding pressure, holding time, return ore particle size, etc.), and clarifies the room temperature performance (compressive strength) and metallurgical performance (reducibility, low temperature reduction pulverization performance, melting drop performance, etc.). All technical effects have been verified by experiments and have direct guiding significance for actual production.

[0077] (3) To address the shortcomings of single organic binders being unstable at high temperatures and single inorganic binders having insufficient connectivity, the room temperature strength and high temperature stability of cold-pressed briquettes were balanced through precise proportioning and modification of organic components (polyacrylamide, gelatin, etc.) and inorganic components (sodium metasilicate with zero water, etc.). This reduced the adverse effects of elements such as potassium and sodium in the binder on the smooth operation of the blast furnace, achieving a breakthrough in existing binder technology.

[0078] (4) The fine-grained sintered return ore cold pressing process has low cost, simple equipment, and significantly lower energy consumption than the traditional sintering process. It is also easy to manage, highly adaptable to raw materials, and suitable for mass production. At the same time, it reduces the recycling and re-firing of sintered return ore, alleviates the problem of resource accumulation, and reduces the energy consumption and CO2 emissions of the sintering process, which is in line with the trend of low carbon and environmental protection.

[0079] (5) Technical value of combining grading and screening with cold pressing: By grading and screening fine sintered return ore (e.g., controlling particle size <2mm) and combining it with cold pressing process, not only can the existing problems of sintered return ore treatment be overcome, but the quality of sintered ore is also indirectly improved and production energy consumption is reduced, which has important industrial application value.

[0080] (6) This application achieves efficient utilization of fine sintered ore by using a composite binder with a specific ratio and combining it with an optimized fine sintered ore cold pressing process. The cold pressing ore produced has stable performance and is suitable for blast furnace requirements. It is both environmentally friendly and economical, effectively solving the technical problems of traditional sintered ore processing.

[0081] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing fine-grained sintered return ore cold-pressed briquettes, the method comprising: Fine-grained sintered return ore raw material is mixed with a composite binder to obtain the first mixture; Water is added to the first mixture to obtain the second mixture; The second mixture is pressed into shape to obtain green pellets; as well as The green pellets are dried and cured to obtain cold-pressed blocks; The composite adhesive is composed of organic and inorganic components. The organic components include at least one of polyacrylamide, gelatin, and phenolic resin, and the inorganic components include at least one of anhydrous sodium metasilicate and anhydrous potassium carbonate. The mass of the composite binder is 5% to 8% of the mass of the fine-grained sintered return ore raw material.

2. The method according to claim 1, characterized in that, The particle size of the fine-grained sintered return ore raw material is <2mm.

3. The method according to claim 1, characterized in that, The composite adhesive is composed of anhydrous sodium metasilicate and phenolic resin, and the mass ratio of anhydrous sodium metasilicate to phenolic resin is 3:

2.

4. The method according to claim 1, characterized in that, The composite adhesive is composed of sodium metasilicate with zero water and polyacrylamide, and the mass ratio of sodium metasilicate with zero water to polyacrylamide is 3:

4.

5. The method according to claim 1, characterized in that, The composite adhesive is composed of anhydrous sodium metasilicate, polyacrylamide, gelatin, phenolic resin and anhydrous potassium carbonate, and the mass ratio of the anhydrous sodium metasilicate, the polyacrylamide, the gelatin, the phenolic resin and the anhydrous potassium carbonate is 3:4:2:2:

2.

6. The method according to claim 1, characterized in that, The composite adhesive is composed of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin, and the mass ratio of sodium metasilicate with zero water, polyacrylamide, gelatin and phenolic resin is 3:4:2:

2.

7. The method according to claim 1, characterized in that, The composite adhesive is composed of sodium metasilicate with zero water and gelatin, and the mass ratio of sodium metasilicate with zero water to gelatin is 3:

2.

8. The method according to claim 1, characterized in that, The mass of the water is 3% to 5% of the total mass of the first mixture.

9. The method according to claim 1, characterized in that, The pressing pressure is 9MPa to 12MPa, and the holding time is 4min to 6min.

10. The method according to claim 1, characterized in that, The cold-pressed block meets the following performance requirements: Cold compressive strength is 800N~3000N; The reduction performance is 70%–88%; The low-temperature reduction pulverization performance is 65%–75%; The droplet melting properties meet the following requirements: T10 is 1070℃~1080℃, T40 is 1180℃~1280℃, ΔTB is 110℃~200℃, Ts is 1240℃~1340℃, Td is 1500℃~1585℃, ΔT is 245℃~260℃, ΔPmax is 12kPa~25kPa, and S is 1700kPa•℃~2800kPa•℃.

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