【作者】 黄云；

【导师】 伍成波；

【作者基本信息】 重庆大学 ， 冶金工程， 2020， 硕士

【摘要】 随着钢铁工业的急剧发展,冶金粉尘的数量迅速增加,如果对这些粉尘没有处理好,不仅会造成资源的巨大浪费,还会造成环境的严重污染。目前转底炉技术处理冶金粉尘应用最为广泛,其金属化球团产品主要用于高炉生产,提高金属化球团的强度就显得格外的重要;同时金属化球团的生产是一个高耗能的过程,如何提高含碳球团的传热条件以节省金属化球团生产过程中热能的消耗则成为了一个重要的研究课题。本文着重围绕金属化球团的传热以及其抗压强度展开了研究。为了得到较高强度及传热条件好的金属化球团,首先从理论入手,介绍了冶金粉尘含碳球团在还原过程中,铁氧化物还原和氧化锌还原的热力学;对于氧化性气氛中含碳球团的还原特性,利用双向气—固反应动力学模型进行了分析。然后通过实验系统地研究了碱度对球团抗压强度和熔点的影响,以及球团的焙烧温度和焙烧时间对金属化球团抗压强度的影响;接着对焙烧过程中,球团的体积收缩和失重进行了研究,其中包括焙烧温度和焙烧时间对球团体积收缩和失重的影响,以及碱度对球团体积收缩的影响。对于球团在还原过程的传热特性研究,本文先以某钢厂的冶金粉尘为实验原料,通过圆柱体模具对冶金粉料进行压块,利用温度采集系统对球团传热进行了实验研究,讨论了不同炉膛温度以及不同粉料碱度对球团传热的影响。最后通过建立三维圆柱体球团传热数学模型,对球团在还原过程的传热过程进行了仿真并利用传热实验对模型进行验证。通过研究得出以下主要结论:(1)金属化球团的抗压强度随着焙烧温度和焙烧时间的增加呈先增加后减小的趋势,当焙烧温度为1270℃,焙烧时间为22min时,金属化球团有较高的强度。当球团碱度小于1.2时,金属化球团的抗压强度随着碱度的增加而减小;当球团碱度大于1.2后,金属化球团的抗压强度又逐渐增加。(2)在不同炉膛温度的传热实验中,炉膛温度越高,球团传热速率会逐渐增大,圆柱体球团1/2高处的中心截面上,表面点、1/2半径点和中心点温度达到与炉膛相接近所需的时间越短,球团截面上各点间的温差会逐渐增大。当炉膛温度为1200℃,传热进行到22min时,球团表面点、1/2半径点和中心点的温度为别为1180.2℃、1161.2℃和1117.9℃。(3)在不同碱度焙烧实验中,随着球团碱度的增加,球团传热速率会逐渐降低,圆柱体球团1/2高处的中心截面上,表面点、1/2半径点和中心点温度达到与炉膛相接近所需的时间越长,球团表面与内部的温差会逐渐增大。传热进行到22min时,不同碱度的球团1/2高处的中心截面上,其表面点温度相差不大,都在1180℃左右,球团1/2半径点和中心点的温度随着碱度的增加而降低。更多还原

【Abstract】 With the rapid development of the iron and steel industry,the amount of metallurgical dust has increased rapidly.If these dusts are not handled properly,it will not only cause a huge waste of resources,but also cause serious environmental pollution.At present,the rotary hearth furnace technology is the most widely used for processing metallurgical dust.Its metallized pellet products are mainly used in blast furnace production.It is particularly important to increase the strength of metallized pellets;at the same time,the production of metallized pellets is a high energy-consuming process.How to improve the heat transfer conditions of carbon-containing pellets to save the heat energy consumption during the production of metal ized pellets has become an important research topic.This paper focuses on the heat transfer and compressive strength of metallized pellets.In order to obtain metallized pellets with higher strength and good heat transfer conditions,first of all,the thermodynamics of iron oxide reduction and zinc oxide reduction in the reduction process of metallurgical dust carbon-containing pellets are introduced from theory;the reduction characteristics of carbon-containing pellets in an oxidizing atmosphere were analyzed using a two-way gas-solid reaction kinetic model.Then the effects of alkalinity on the compressive strength and melting point of the pellets,as well as the effect of the calcination temperature and baking time of the pellets on the compressive strength of the metalized pellets were systematically studied through experiments;next,the volume shrinkage and weight loss of the pellets during the calcination process were studied,including the effects of calcination temperature and baking time on the volume shrinkage and weight loss of the pellets,and the effect of alkalinity on the volume shrinkage of pellets.For the heat transfer characteristics of the pellets during the reduction process,this paper first uses the metallurgical dust of a steel plant as the experimental raw material,compacts the metallurgical powder through the cylindrical mold,and uses the temperature collection system to conduct experimental research on the heat transfer of the pellet,The effects of different furnace temperatures and different powder alkalinity on the heat transfer of pellets are discussed.Finally,through the establishment of a three-dimensional cylindrical pellet heat transfer mathematical model,the heat transfer process of the pellet in the reduction process was simulated and the model was verified by heat transfer experiments.Through research,the following main conclusions are drawn:(1)The compressive strength of metallized pellets increases first and then decreases with the increase of calcination temperature and calcination time.When the calcination temperature is 1270 ℃ and the calcination time is 22 min,the metallized pellets have a higher strength.When the basicity of the pellet is less than 1.2,the compressive strength of the metalized pellet decreases with the increase of the basicity;when the basicity of the pellet is greater than 1.2,the compressive strength of the metalized pellet gradually increases.(2)In the heat transfer experiment with different furnace temperatures,the higher the furnace temperature,the heat transfer rate of the pellet will gradually increase.On the center cross section of the 1/2 height of the cylindrical pellet,the surface point,1/2radius point The shorter the time required for the temperature close to the center point to be close to the furnace,the temperature difference between t he points on the cross section of the pellet will gradually increase.When the furnace temperature is 1200℃ and the heat transfer is carried out to 22 minutes,the temperature of the pellet surface point,1/2 radius point and center point are 1180.2℃,1161.2℃ and 1117.9℃.(3)In the calcination experiment with different basicities,with the increase of the basicity of the pellet,the heat transfer rate of the pellet will gradually decrease.The longer the time required for the temperature of the point and center point to be close to the furnace,the temperature difference between the surface and the interior of the pellet will gradually increase.When the heat transfer is carried out to 22 minutes,the temperature of the surface point on the center of the 1/2 high place of the pellets with different alkalinities is not much different,both are around 1180 ℃,and the temperature of the 1/2 radius point and the center point of the pellets varies As the alkalinity increases,it decreases.更多还原