Method for improving sinter homogeneity after sinter pallet expansion

Abstract

A method for improving sintering homogeneity after expanding the capacity of a sintering trolley, wherein the expansion refers to the lateral expansion of the sintering trolley, and the method includes: uniformly distributing the material in three transverse sections, with different materials in the middle and end sections; adding additives to the middle section to increase the air permeability and sintering rate of the central area; using the centerline of the trolley's cross-section as a reference, and calculating the range and amount of additives added to the central area using empirical formulas. This invention is simple, direct, and effective. The three-section transverse material distribution is more conducive to homogeneous sintering. The direct calculation of the central area range reduces the time spent on repeated on-site trials, playing a crucial role in timely adjustments during production, improving production efficiency, and also improving the quality of the sintered product after trolley expansion. This provides a convenient and efficient new approach for homogeneous production after sintering expansion.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for improving sintering homogeneity after expanding the capacity of a sintering trolley. Background Technology

[0002] As a fundamental industry of the national economy, the steel industry faces the triple challenges of capacity expansion, resource constraints, and environmental pressures. Since the beginning of the 21st century, global steel production has experienced explosive growth. China's crude steel output jumped from 129 million tons in 2000 to 1.019 billion tons in 2023, accounting for 54.2% of global production. This large-scale production model places higher demands on the supply of sintered ore: [The text abruptly shifts to a seemingly unrelated topic about 4000m³ sintering capacity.] 3 The blast furnace requires more than 12,000 tons of sinter per day, equivalent to the daily output of a traditional 300m³ blast furnace. 2 The daily capacity of the sintering machine is 1.5 times that of the sintering machine. However, the expansion of the sintering process is constrained by land approval restrictions, environmental capacity limitations, and investment cost pressures. The construction cycle of new production lines is as long as 2 to 3 years, which is far from matching the speed of blast furnace renovation. This has led to a common contradiction of "iron-sintering capacity imbalance". At present, the production of pellets in my country generally suffers from low quality problems, mainly including low iron content, poor strength, large quality fluctuations, and instability. The quality of finished pellets is closely related to the quality of raw materials (iron concentrate and various additives), process flow, roasting system, and equipment performance.

[0003] The sintering process faces a triple constraint: total SO2 and NOx emissions, and carbon emission intensity. Traditional production expansion models, if simultaneously increasing flue gas emissions, will necessitate the retrofitting of end-of-pipe treatment facilities, significantly increasing investment costs. This contradiction is driving technological innovation towards "increased production without increased emissions," pushing processes such as flue gas recirculation and homogeneous sintering to become standard features for capacity expansion.

[0004] Currently, steel companies generally adopt the method of keeping the lower part of the sintering trolley unchanged and expanding the upper part by thickening the material layer. As the sintering trolley is widened laterally, the gas flow pattern of the sintering trolley changes, and the edge effect of the sintering process becomes more obvious, resulting in a decrease in the overall homogeneity of sintering, a decrease in the quality of sintered ore, and an increase in the return rate of ore.

[0005] CN202311202143.6 discloses a method for homogeneous sintering of iron ore with an ultra-high material layer. In this method, iron ore is ore-matched according to particle size, liquid-phase master batch composition and ratio. After mixing and granulation, the material is distributed according to the different particle size ratios, composition and fuel quantity of the mixed material, and sintered into ore within the range of the total heat obtained from fuel combustion and heat storage in the material layer being 4.0 - 6.0 GJ / t - raw material, thus obtaining sintered ore; in the mixed material, the proportion of the liquid-phase master batch is 30 - 70%, and the liquid-phase master batch is mainly the -3 mm mixed material after granulation; the liquid phase obtained after reaction includes the following main components in parts by mass: 15 - 30 parts of CaO, 1 - 4 parts of Al<subgt;2< / subgt;O<subgt;3< / subgt>, 3 - 6 parts of SiO<subgt;2, and 0 - 4 parts of MgO. According to the ore-forming characteristics of sintered ore, by strictly controlling the parameter settings of the particle size, composition and heat distribution of the mixed material, the synergistic effect of particle size - heat and composition is stimulated, which not only ensures the uniformity of the liquid-phase composition in the sintering process, but also greatly improves the fuel utilization rate, reduces the consumption of solid fuel and carbon emissions, and improves the uniformity and stability of sintered ore.

[0006] A method for homogeneous ore matching of dolomite powder into the blended ore pile, CN119842997A. This invention relates to the technical field of iron and steel metallurgy, and specifically relates to a method for homogeneous ore matching of dolomite powder into the blended ore pile, including: (1) providing ore powder for building the blended pile: the ore powder for building the blended pile contains at least 3 kinds of iron ore powders; (2) screening out iron ore powders with a particle size ≥ 3 mm and a proportion ≥ 30 wt%, a balling index ≥ 0.35 and a loss on ignition ≥ 6 wt%. When there are two kinds of screened iron ore powders, they are respectively denoted as iron ore powder I and iron ore powder II; when there are more than two kinds of screened iron ore powders, then select the two iron ore powders with the largest content in the blended material obtained after building the blended pile, and denote them as iron ore powder I and iron ore powder II respectively; (3) sequentially feed the materials in the order of iron ore powder I, dolomite powder, and iron ore powder II onto the batching belt, and then mix and build the pile with the homogeneous material and the remaining iron ore powders. This method mixes dolomite powder into the blended ore pile, reduces the feeding pressure of the flux crushing system, and stabilizes the quality of sintered ore.

[0007] Existing literature has not covered the research on improving sintering homogeneity after expanding the sintering trolley. Currently, after the conventional sintering trolley is expanded, on-site operators need a lot of time and explore the method of improving uniform sintering of sintered ore during the sintering production process, which not only wastes time but also greatly increases costs. In the early exploration stage, the sintering finished product rate will also be reduced, increasing costs.

[0008] In view of the above problems, the present invention proposes an empirical method that is relatively simple and low-cost and can improve sintering homogeneity after expanding the sintering trolley, which can effectively improve the sintering finished product rate and sintering quality after sintering expansion. Summary of the Invention

[0009] The purpose of this invention is to provide a method for improving sintering homogeneity after expanding the capacity of a sintering trolley. This method utilizes long-term collected and analyzed data to summarize, extract, and fit the data, providing a way to reduce edge effects and improve sintering homogeneity after lateral expansion of the sintering trolley. Currently, there is no effective method to directly address the issue of uneven sintering quality in iron ore after expansion; therefore, a simple and effective production method is urgently needed to address the problem of uneven sintering leading to decreased sintering quality. This invention provides a specific treatment method that is simple, direct, and effective. The three-section lateral material distribution is more conducive to homogeneous sintering. The central area range is directly calculated, reducing the time spent on repeated on-site trials and playing a crucial role in timely adjustments during production, improving production efficiency, and also improving the quality of the sintered product after trolley expansion. This provides a convenient and efficient new approach for homogeneous sintering production after expansion.

[0010] To achieve the above objectives, the present invention employs the following technical solution: A method for improving sintering homogeneity after expanding the capacity of a sintering trolley, wherein the expansion is a lateral expansion of the sintering trolley, and the method for improving sintering homogeneity includes: uniformly distributing the material in three lateral sections, with different material distribution in the middle and end sections; adding additives to the middle section to increase the air permeability and sintering rate of the central area; the central area is estimated using the centerline of the trolley's cross-section as a reference, and the range of the central area is calculated using the following empirical formula: ; Symbols in the formula: L is the width of the central area where the additive needs to be added, in mm; L y Width of the sintering trolley, in mm; H represents the height of the sintered material surface, in mm; N represents the increased width of the sintering trolley after expansion, in mm.

[0011] Furthermore, the amount of additive added in the central region, ω (%), is calculated using the following formula: ; Symbols in the formula: H represents the height of the sintered material surface, in mm; P represents the negative pressure of the exhaust system, measured in kPa. D represents the average particle size of the sintered mixture, in mm.

[0012] Furthermore, the exhaust negative pressure P ranges from -11 to -18 kPa, and the average particle size of the sintered mixture ranges from 50 to 61 mm.

[0013] Furthermore, the width L of the sintering trolleyy The sintering material height H ranges from 3500 to 4500 mm, the sintering material surface height H ranges from 5000 to 8500 mm, and the sintering trolley expansion width N ranges from 200 to 500 mm.

[0014] Furthermore, the additive is made from the following raw materials in parts by weight: 30-35 parts blast furnace dust, 20-25 parts biomass, 15-20 parts iron oxide scale, and 15-20 parts plastic waste. The above raw materials are crushed and mixed and then pre-formed into balls to form particles with a particle size of 3-6 mm as mother balls. Then, sintering raw materials are added for subsequent processes such as first mixing and second mixing.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes long-term collected and analyzed data to summarize, extract, and fit a method for reducing edge effects and improving sintering homogeneity after lateral expansion of sintering trolleys. This method directly provides specific processing steps, is simple, direct, and effective. The three-section lateral material distribution is more conducive to homogeneous sintering. The central area range is directly calculated, reducing the time spent on repeated on-site trials and playing a crucial role in timely adjustments during production, improving production efficiency, and also enhancing the quality of sintered products after trolley expansion. This provides a convenient and efficient new approach for homogeneous production after sintering expansion. Simultaneously, the additives are all made from waste materials, preventing metallurgical waste from being spilled or accumulated, minimizing environmental pollution from metallurgical slag. Compared with existing technologies, this invention has stronger applicability and is more suitable for expanding existing sintering production lines. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the cross-section of the sintering trolley after expansion.

[0017] In the diagram: 1. Material surface; 2. Side baffle of the trolley; 3. Grate bar. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the specific implementation methods of this invention will be further described below in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of this invention. These embodiments are only general descriptions of the content of this invention and do not limit the content of this invention.

[0019] Example: A steel plant is expanding its sintering production lines. The method of this invention is used to improve the homogeneity of sintering: the material is evenly distributed in three sections in the transverse direction. The material distribution in the middle area is different from that in the two end areas. Additives are added to the middle area to increase the air permeability and sintering rate of the central area. The central area is based on the center line of the trolley cross-section. The range of the central area is calculated using the following empirical formula (1): ; Symbols in the formula: L is the width of the central area where the additive needs to be added, in mm; L y Width of the sintering trolley, in mm; H represents the height of the sintered material surface, in mm; N represents the increased width of the sintering trolley after expansion, in mm.

[0020] The amount of additive added in the central region, ω (%), is calculated using the following formula (2): ; Symbols in the formula: H represents the height of the sintered material surface, in mm; P represents the negative pressure of the exhaust system, measured in kPa. D represents the average particle size of the sintered mixture, in mm.

[0021] The additive is made from the following raw materials in the following proportions by weight: 35 parts blast furnace dust, 25 parts biomass straw, 20 parts iron oxide scale, and 20 parts plastic waste. The above raw materials are crushed and mixed and then pre-formed into balls to form particles with a particle size of 3-6 mm as mother balls. The sintering raw materials are then added and mixed.

[0022] On-site data collection. The collected data results are shown in Table 1: Table 1 Data collected in the examples According to the technical solution of the present invention, the effective data collected in Examples 1 to 5 were used to calculate the central region and the amount of additive added in the central region by substituting empirical formulas (1) and (2). The production parameters of the production process in the examples are shown in Table 2. Real-time finished sintered ore was sampled and analyzed on-site. The results are shown in Table 3.

[0023] Table 2 Calculation parameters of the method in the embodiment Table 3 Comparison of estimated FeO content and actual value in pellets from the examples Using the embodiment of the method for improving sinter homogeneity after expanding the sintering trolley in the present invention, the ore yield of the finished sinter is 81.6%~83.7%, and the drum strength is 77.1%~80.4%. The ore yield and drum strength are increased by 2.7%~4.2% and 2.4%~3.9% respectively compared with normal production. This method can effectively improve the sinter homogeneity and has good stability.

[0024] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. It should be understood that the disclosed technical content in the several embodiments provided in this application can be implemented in other ways.

Claims

1. A method for improving sintering homogeneity after expanding the capacity of a sintering trolley, characterized in that, The expansion of the sintering trolley is a lateral expansion method to improve sintering homogeneity. This includes: uniformly distributing the material in three lateral sections; different material distribution in the middle and end sections; adding additives to the middle section; and calculating the range of the central section using the centerline of the trolley's cross-section as a reference. ； Symbols in the formula: L is the width of the central area, in mm; L y Width of the sintering trolley, in mm; H represents the height of the sintered material surface, in mm; N represents the increased width of the sintering trolley after expansion, in mm.

2. The method for improving sintering homogeneity after expanding the sintering trolley according to claim 1, characterized in that, The amount of additive added in the central region, ω (%), is calculated using the following formula: ； Symbols in the formula: H represents the height of the sintered material surface, in mm; P represents the negative pressure of the exhaust system, measured in kPa. D represents the average particle size of the sintered mixture, in mm.

3. The method for improving sintering homogeneity after expanding the sintering trolley according to claim 2, characterized in that, The exhaust negative pressure P ranges from -11 to -18 kPa, and the average particle size of the sintered mixture ranges from 50 to 61 mm.

4. The method for improving sintering homogeneity after expanding the sintering trolley according to claim 1, characterized in that, Sintering trolley width L y The sintering material height H ranges from 3500 to 4500 mm, the sintering material surface height H ranges from 5000 to 8500 mm, and the sintering trolley expansion width N ranges from 200 to 500 mm.

5. The method for improving sintering homogeneity after expanding the sintering trolley according to claim 1, characterized in that, The additive is made from the following raw materials in the following proportions by weight: 30-35 parts blast furnace dust, 20-25 parts biomass, 15-20 parts iron oxide scale, and 15-20 parts plastic waste. The above raw materials are crushed and mixed and then pre-formed into balls to form particles with a particle size of 3-6 mm as mother balls. The sintering raw materials are then added and mixed.

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