【作者】 王锐；

【导师】 吕学伟；

【作者基本信息】 重庆大学 ， 冶金工程， 2024， 硕士

【摘要】 我国拥有丰富的钒钛磁铁矿,是钢铁行业减少对进口铁矿石依赖的重要特色资源,通过数学模型揭示钒钛矿烧结机理以达到降低生产成本和提高钒钛矿利用率的目标,对我国钢铁行业稳定安全发展至关重要。钒钛磁铁矿同化的核心是固相生成和固液溶解反应,该步骤对烧结矿的质量和冶金性能起着决定性作用。本文基于钒钛磁铁矿烧结主要反应和菲克定律,推导出了固相反应模型和固液溶解模型,对钒钛磁铁矿烧结同化过程进行了数学解析。通过模型计算和烧结杯实验相结合,研究了提高钒钛矿配比和高钒钛矿配比下碱度对烧结矿产质量指标的影响规律,同时提出钒钛矿烧结的优化工艺方案。论文的主要研究内容及结论如下:（1）考虑钒钛矿烧结固固反应特点、反应物扩散速率、反应物粒径等因素,通过数学推导,构建了钒钛矿固固反应模型,并实现了数值化求解。根据构建的钒钛矿固固反应模型,钒钛矿烧结在固相反应阶段依次生成钙钛矿、钛赤铁矿、钛铁尖晶石、硅酸二钙和铁酸钙。在钒钛矿固相反应阶段,由于Ti O₂的存在,反应产物中钙钛矿和钛赤铁矿的生成量约占总量的10%,而低熔点的铁酸钙仅占3.1%,与常规烧结产物相比有显著差异,对后续液相生成产生了一定影响。（2）基于热力学计算,采用两步拟合法得到钒钛矿烧结液相七元渣系的粘度计算模型,该模型能够较好预测钒钛矿烧结过程中渣系的粘度。考虑钒钛矿烧结固液溶解特点、固相颗粒粒径、初始液相量、组分在液相中扩散等因素,通过数学推导,建立了钒钛矿固液溶解模型,并实现了解析化。基于此模型可知含钛物相如钙钛矿、钛赤铁矿、钛铁尖晶石等对钒钛矿固液溶解过程产生了重要影响。这些物相的存在导致初始铁酸钙含量减少,溶解阶段氧化物的溶解驱动力减小,生成液相量不足,直接影响了成品烧结矿的冷强度。随着钛含量增加,液相生成愈加困难,未反应氧化物比例增加,形成的烧结矿具有更多孔洞,进而恶化烧结矿冶金性能。（3）根据阿伦尼乌斯方程和化学动力学原理,建立了焦炭燃烧模型,模型用于整个钒钛磁铁矿同化机理模型的升温制度。采用实际生产原料进行模拟计算,将钒钛磁铁矿烧结同化机理模型数字化。研究了不同原料条件对烧结过程的影响。增加配碳量可以提高烧结过程的热输入,从而促进液相量的生成。在Si O₂含量一定的情况下,增加碱度可以改善铁酸钙生成的热力学条件,进而促进烧结矿中SFCA的生成。适当控制矿粉氧化物的粒径不仅可以改善制粒过程和优化料层透气性,还有助于促进颗粒向液相中溶解,减少未反应氧化物的比例,从而促进液相的生成。（4）采用钒钛矿烧结同化机理模型预测了不同钒钛矿配比和碱度对烧结的影响,并通过烧结杯实验验证,证明了模型的可靠性。随着钒钛磁铁矿配比从55%增加到85%,烧结矿的成品率从82.13%下降至78.88%,当配比超过65%时,烧结矿的转鼓强度下降到约60%,然而,烧结矿的落下强度整体上在81%左右波动。在钒钛矿配比为70%的基础上,碱度从1.7增加至2.0能显著提高烧结矿的冶金性能和产质量指标;碱度从2.0增加到2.2时,转鼓强度达到最大值,其余指标改善不明显。因此,采用钒钛矿配比为70%且碱度为2.0的工艺条件可以确保烧结过程中有足够的液相量,使成品烧结矿具有适宜的物相组成。更多还原

【Abstract】 There is abundant vanadium-titanium magnetite in China,which is an important characteristic resource for reducing the steel industry’s dependence on imported iron ore.Revealing the sintering mechanism of vanadium-titanium ore through mathematical models is crucial for achieving the goals of increased utilization efficiency and reduced production costs,which are essential for the stable and secure development of the steel industry in China.The core of vanadium-titanium magnetite assimilation lies in solid-phase generation and solid-liquid dissolution reactions,which play a decisive role in the quality and metallurgical performance of sinter.This paper,based on the main reactions of vanadium-titanium magnetite sintering and the Fick’s law,deduces solid-phase reaction models and solid-liquid dissolution models,providing a digital analysis of the assimilation process of vanadium-titanium magnetite sintering.By combining model calculations with sintering pot experiments,the study investigates the influence of alkalinity on the quality indicators of sintered ore under increased vanadium-titanium ore blending and high vanadium-titanium ore blending,and proposes an optimized sintering process for vanadium-titanium ore.The main research contents and conclusions of the paper are as follows:（1）Considering factors such as the solid-state reaction characteristics of vanadium-titanium ores,the diffusion rate of reactants,and the particle size of reactants,a solid-state reaction model for vanadium-titanium ores was constructed through mathematical deduction and analytical methods.According to this model,during the solid-phase reaction stage of vanadium-titanium ore sintering,perovskite,titanomagnetite,titanomagnetite spinel,dicalcium silicate,and calcium iron oxide are sequentially generated.During the solid-phase reaction stage of vanadium-titanium ores,due to the presence of Ti O₂,the production of perovskite and titanomagnetite accounts for approximately 10%of the total,while the low-melting-point calcium iron oxide accounts for only 3.1%,showing significant differences compared to conventional sintering processes and exerting a certain influence on subsequent liquid-phase generation.（2）Based on thermodynamic calculations,a two-step fitting method was used to derive a viscosity calculation method for the seven-component slag system in vanadium-titanium ore sintering.This method can effectively predict the viscosity of the slag system during the vanadium-titanium ore sintering process.Considering the solid-liquid dissolution characteristics of vanadium-titanium ore sintering,solid-phase particle size,initial liquid phase amount,component diffusion in the liquid phase,and other factors,a solid-liquid dissolution model for vanadium-titanium ores was established through mathematical deduction and analytical methods.Based on this model,it is known that phases containing titanium such as perovskite,titanomagnetite,and titanomagnetite spinel have a significant impact on the solid-liquid dissolution process of vanadium-titanium ores.The presence of these phases leads to a reduction in initial calcium iron oxide content,a decrease in the dissolution driving force of oxides during the dissolution stage,and insufficient generation of the liquid phase.The high melting point and poor bonding properties of titanium-containing phases also result in insufficient generation of the newly formed liquid phase,directly affecting the cold strength of the final sintered ore.As the titanium content increases,liquid phase generation becomes more difficult,the proportion of unreacted oxides increases,more pores are formed in the sintered ore,and consequently,the metallurgical properties deteriorate.（3）Based on the Arrhenius equation and principles of chemical kinetics,a combustion model for coke was established.This model serves as the heating system in the overall assimilation mechanism model for vanadium-titanium magnetite.Simulations were conducted using actual production materials to digitize the assimilation mechanism model for vanadium-titanium magnetite sintering.The effects of different raw material conditions on the sintering process were studied.Increasing the carbon content can enhance the thermal input during sintering,thereby promoting the generation of the liquid phase.Under constant Si O₂ content,increasing alkalinity can improve the thermodynamic conditions for calcium ferrite formation,consequently facilitating the generation of SFCA in the sintered ore.Proper control of the particle size of ore powder oxides not only improves the agglomeration process and optimizes the permeability of the material layer but also helps promote dissolution of particles into the liquid phase,reducing the proportion of unreacted oxides and thus promoting liquid phase generation.（4）The assimilation mechanism model for vanadium-titanium magnetite sintering was used to predict the effects of different vanadium-titanium ore ratios and alkalinity on sintering.Sintering crucible experiments were conducted to validate the model,and the results demonstrated its reliability.As the vanadium-titanium magnetite ratio increased from 55%to 85%,the yield of sintered ore decreased to 78.88%.When it exceeded 65%,the drum strength of the sintered ore decreased to approximately 60%,while the falling strength of the sintered ore fluctuated around 81%.Based on a vanadium-titanium ore ratio of 70%,increasing the alkalinity from 1.7 to 2.0significantly improved the metallurgical performance and product quality indicators of the sintered ore.When the alkalinity increased from 2.0 to 2.2,the drum strength reached its maximum value,while other indicators showed less improvement.Therefore,it is recommended to use a vanadium-titanium ore ratio of 70%and an alkalinity of 2.0 in the process to ensure an adequate amount of liquid phase during sintering,resulting in a suitable phase composition for the final sintered ore.更多还原