【作者】 杨雪峰；

【导师】 姜涛； 范晓慧；

【作者基本信息】 中南大学 ， 钢铁冶金， 2011， 博士

【摘要】 本文以昆明钢铁公司120万吨/年链算机—回转窑氧化球团工艺为对象,并结合其原料结构与生产实际情况,研究了采用云南省及周边地区多种磁/赤混合铁精矿生产氧化球团的可行性及相关技术,并在混合铁精矿造球、焙烧固结及回转窑结圈等方面开展基础理论与工业应用研究。论文的主要结论与创新性如下：1、研究了单一铁精矿和不同配矿条件下混合铁精矿的造球性能,结果表明：昆钢拟用单一铁精矿的造球性能并不好,其造球性能由优到劣的顺序依次为曼南坎>小红山>大红山>优精>巴西。经合理配矿,采用不同种类磁/赤混合铁精矿造球,可在一定程度上弥补单种铁精矿造球性能的不足,显著降低膨润土用量,改善生球质量。研究表明：就造球性能而言,采用云南省及周边地区铁精矿替代进口巴西赤铁精矿是可行的。2、研究了单一铁精矿球团的预热、焙烧性能,其预热性能由优到劣的顺序依次为优精>巴西>小红山>大红山>曼南坎；焙烧预热性能由优到劣的顺序依次为大红山>小红山>优精>巴西>曼南坎。经合理配矿后,混合铁精矿球团的预热、焙烧性能比较接近。对磁/赤混合铁精矿球团焙烧固结机理的研究表明,由磁铁矿氧化生成的次生赤铁矿中Fe2O3的活性较原生赤铁矿中Fe2O3的活性高,因此在磁/赤混合精矿球团焙烧过程中,无论是在预热阶段还是在焙烧阶段,磁铁矿可促进了颗粒间Fe2O3的再结晶连接,有利于降低焙烧温度、提高球团矿强度。3、通过对昆钢回转窑结圈物特性及实验室的模拟试验研究,查明了煤气供热回转窑结圈物的形成机理。结果表明：与普通球团矿的固结机理基本一致,回转窑结圈物是以Fe2O3再结晶的固相固结为主,低熔点物质的液相固结起辅助作用。在正常操作温度下,回转窑结圈物以及铁精矿不会发生软熔,原料结构、脉石成分和含量的变化均不会导致物料变形、软化温度的明显改变。因此,液相粘结不是回转窑结圈形成的主要形式。模拟试验表明：粉末是昆钢回转窑结圈的物质基础,操作制度波动是导致回转窑结圈的外因,碱金属的存在可促进结圈物的发展。通过调整原料结构、改善生球质量、优化预热焙烧制度,以及规范开/停机制度等,可有效防治回转窑结圈问题。4、在理论研究结果的指导下,昆钢开展了4个阶段的球团生产达产攻关研究,通过优化原料结构、加强原料预处理、优化现场工艺条件、稳定操作制度,较好解决了投产初期生产成球率低、回转窑结圈严重等问题,实现了全云南省内及周边混合铁精矿生产氧化球团的目标,球团产量和质量指标获得明显改善：生产成球率由初期的34.32%提高到66.32%,球团矿抗压强度从投产后第1阶段的1988N/个提高到2497N/个,ISO转鼓指数从93.08%提高到97.46%。昆钢2000m3使用全自产球团矿、取消进口巴西球团矿生产后,高炉炉料结构获得优化,炉况顺行,生产技术经济指标明显改善：高炉产量平均增加1155 t-铁/d,利用系数提高0.563t/m3-d,一级品率提高11.69个百分点,燃料比降低18.32kg/t-Fe,吨铁成本降低56.82元,每年可产生经济效益9490万元。本文针对以磁/赤混合铁精矿为原料所开展的造球性能、焙烧性能、球团固结机理,以及回转窑结圈机理等所开展的基础理论研究,具有较高的理论意义和学术价值；以混合铁精矿为原料采用链箅机—回转窑工艺生产氧化球团的工业实践,对国内其它球团厂采用混合铁精矿生产氧化球团亦具有重要的理论指导和借鉴意义。更多还原

【Abstract】 In this paper, based on the KISC practical situation for the oxidized pellets production by grate-kiln process, feasibility and related techniques by using many kinds of hematite and magnetite bulk concentrates of Yunnan province and surrounding areas to produce oxidized pellets were studied, also the basic theory about iron ore concentrates ballability, thermal hardening and ring-forming of rotary kiln and so forth were studied. The contents include:1. The ballability of single iron concentrates and mixed iron concentrates was studied. The results show that the ballability of single iron concentrates is not good. The ballability of five kinds of iron ore concentrates are ranked from bad to good as follows:Mannankan> Xiaohongshan> Dahongshan> Youjing> Brazil. The results show that rational ore blending can improve quality of pellet and decrease the bentonite addition. Considering the ballability, using iron concentrates of Yunnan province and surrounding areas instead of imported hematite was feasible.2. The preheating and roasting properties of single iron ore concentrates were studied. The preheating properties of iron ore concentrates are ranked from good to bad as follows:Youjing> Brazil> Xiaohongshan> Dahongshan> Mannankan; The roasting and preheating properties are ranked from good to bad as follows:Dahongshan> Xiaohong-shan> Youjing> Brazil> Mannankan. The preheating and roasting properties are close under different scheme of ore blending.The thermal hardening mechanism of mixed magnetite-hematite concentrates in Kunsteel shows that activity of Fe2O3 in the secondary hematite is higher than Fe2O3 in the original hematite. Therefore, during roasting process, either in preheating stage or in roasting stage, the exsiting magnetite promotes the recrystallization of Fe2O3, and can be beneficial to improve pellet strength and reduce roasting temperature.3. Based on the study of characteristics of ring-forming substances in rotary kiln of Kunming Steel and the simulation experiments in laboratory, the ring-forming mechanism of rotary kiln was found. The results showed:the ring-forming substances is dominantly attributed to solid agglomeration of the Fe2O3 phase recrystallization, and partly to liquid phase agglomeration of low melting point substances, which is accordant to that of oxidized pellets. Under the normal operation temperature, the ring-forming substances and iron ore concentrates would not soften and smelt. The deforming and softening temperatures changes with the raw materials structure or the compositions and contents of gangue were not obvious. Therefore, liquid phase agglomeration was not the main reason of ring formation. It has been proved by experiments: Powder is the material basis for ring-forming. The fluctuations of operating duty were the direct cause of ring formation. Alkali metals promote formation and development of ring-forming. During the practical production of oxidized pellets some effective countermeasures have been pertinently adopted to control and prevent the generation of ring formation, such as adjusting raw materials structure, enhancing balling process to improve the quality of green balls, optimizing the process of preheating and roasting, standardizing the blow in/out operation and so on.4. On basis of the above researches, the problems that lower granulating rate in the initial operation period and the serious ring-forming in rotary kiln were solved well, by adjusting raw materials structure, enhancing balling process, optimizing the process conditions, standardizing operation. The output and quality of pellets were increased evidently. The granulation ratio was raised from 34.32% to 66.32%. The pellet compression strength was raised from 1988N to 2497N. ISO tumbler indes was raise from 93.08% to 97.46%. Since the self-produced pellets replaced imported Brazil pellets, the technical and economical index of blast furnace was improved:the blast furnace production of iron increased by 1155t/d. The utilization coefficient of BF increased by 0.563 t/m3·d. The rate of the first class products increased by 11.69%, fuel ratio decreased by 18.32 kg/t-Fe. The total production cost per ton pig iron decreased by 56.82 Yuan. An annual benefit of 94.90 million Yuan can be achieved..In this paper, taking mixed hematite magnetite concentrates as raw material, the ballability, the preheating and roasting properties, the consolidation mechanism and the mechanism of the ring-forming were studied, which has a higher theoretical value and academic value. The industrial practices, taking mixed hematite magnetite concentrates as raw material, using grate-kiln pelletizing process for producing pellet, can provide the theory instruction for some domestic pelletizing Plant.更多还原