【作者】 张元波；

【导师】 姜涛； 黄柱成；

【作者基本信息】 中南大学 ， 钢铁冶金， 2006， 博士

【摘要】 随着我国钢铁工业的快速发展，对国内复杂铁矿资源的开发利用具有重要的现实意义。含锡锌复杂铁矿是一类典型的难选难冶矿石，在我国储量很大。本论文以取自于内蒙古黄岗含锡锌铁精矿为研究对象，开展了含锡锌铁精矿球团弱还原焙烧制备高炉用球团矿并综合回收锡和锌的物化基础及新工艺研究。在研究含锡锌铁精矿基本物化性能的基础上，采用光学显微镜、XRD、SEM及电子探针等微观测试方法对其工艺矿物学进行了详细研究，发现锡石和闪锌矿多以微细粒单体或不规则粒状与磁铁矿构成连生体或包裹体，导致Fe与Sn、Zn的选矿分离十分困难。铁、锡和锌氧化物的还原热力学研究表明，当控制气相温度为974℃＜T＜1250℃，气相中CO浓度为7.6％＜CO％＜16.8％时，可实现铁与锡、锌的分离。SnO₂被还原为SnO以气态形式挥发，ZnO可被还原为Zn蒸汽而挥发，高价铁氧化物（Pe₂O₃或Fe₃O₄）仅被还原为FeO。以CO气体为还原剂，对磁铁矿球团的Fe₃O₄→FeO阶段的等温及非等温还原动力学进行了研究。结果表明，非等温还原的反应控制机理与等温还原的基本一致。非等温条件下，当温度为600～920℃时，Fe₃O₄→FeO阶段的还原反应由界面化学反应所控制；温度大于920℃时，还原反应为界面化学反应与扩散混合控制。对含锡锌铁精矿球团中的SnO₂和ZnO进行了等温还原动力学研究，结果表明：当温度为950℃和1000℃，SnO₂的还原符合界面化学反应控制；温度为1050℃和1100℃时，还原反应为化学界面反应与扩散混合控制。当温度为950～1100℃时，ZnO的还原符合界面化学反应控制。在研究含锡锌铁精矿球团制备、干燥、预热及焙烧技术特性的基础上，首次提出了含锡锌铁精矿球团—弱还原焙烧综合利用Sn、Zn和Fe的工艺路线，并在链篦机—回转窑模拟装置上进行了扩大化工艺参数研究。在优化条件下，球团内配1～2％无烟煤对Sn和Zn的挥发有少许改善作用，与没有内配无烟煤的球团相比，Sn和Zn挥发率提高约0.5～1.5％，球团中Sn和Zn挥发率分别大于80％和70％，残余Sn、Zn含量均小于0.06％。成品球团矿抗压强度大于2480N／个，ISO转鼓大于97％，耐磨指数小于2％。试验结果表明，新工艺有效地实现了含锡锌铁精矿中铁、锡和锌的分离，同时球团矿抗压强度和残余Sn和Zn的含量均满足高炉生产要求。首次采用Leica图像分析软件Qwin测量人造球团矿中各主要组成矿物的实际面积，主要组成矿物经光学显微镜、XRD、SEM和X射线能谱成分分析等测试技术证实，并结合元素分析结果，计算出球团中实际矿物的质量百分含量。在此基础上，首次对弱还原焙烧球团矿的固结机理进行研究，结果表明：弱还原焙烧球团矿的固结方式是以富氏体再结晶固结为主。高温下富氏体颗粒发生再结晶，互连成片，并与充填在富氏体颗粒之间的橄榄石紧密镶嵌，使球团矿具有较高的强度。本论文的研究为含锡锌复杂铁精矿的综合利用提供了新的途径，为新工艺的工业化实施提供了可靠的技术参数。更多还原

【Abstract】 With the rapid development of iron & steel industry of China, it is of significance to intensify utilization of domestic complex iron ore resources. The complex iron ores containing fin and zinc are typical intractable ones, great reserves of which are found in China. In this research, tin, zinc-containing iron concentrate, taken from Huanggang in Inner Mongolia Autonomous Region, was used to investigate the physicochemical fundamental and new technology of preparation of pellets for blast furnace by weak reduction masting and recovery of tin and zinc.Based on the investigation of basic physicochemical properties of the tin, zinc-bearing iron concentrates, the process mineralogy of them were detailedly researched by using advanced testing methods, such as optical microscope, SEM, XRD and electron probe. It was found that magnetite in the concentrates was closely symbiotic or enwrapped by cassiterite and sphalerite, which mostly existed in the shapes of superfine monomer or anomalistic granules. So it was difficult to separate fin and zinc from the iron concentrates.The analytical results of reduction thermodynamics of iron, fin and zinc oxides showed that, tin and zinc could be separated from iron when reduction temperature was between 974℃and 1250℃, moreover, CO% in the gas wasless than 16.8% but above 7.6%. SnO₂ was reduced and volatilized as gaseous SnO, ZnO could be reduced into Zn_g and Fe₂O₃ or Fe₃O₄ were only reduced to FeO under the conditions.The isothermal and non-isothermal reduction kinetics of Fe₃O₄→FeO stage was investigated using CO as a reduction agent. The results indicated that the controlling mechanism of isothermal reduction reaction was similar to that of the non-isothermal reaction. Under the non-isothermal conditions, the reaction of Fe₃O₄→FeO stage was controlled by interfacial chemical reaction when reduction temperature was between 600～920℃, however, it was controlled by a mixed chemical reaction and diffusion when the temperature was above 920℃. The isothermal reduction kinetics of SnO₂ and ZnO in the concentrate pellets containing tin and zinc were carded out and it was found that the reduction of SnO₂ was controlled by interfacial chemical reaction when temperature was at 950℃and 1000℃, whereas, it was controlled by a mixed mechanism of chemical reaction and diffusion when the temperature was at 1050℃and 1100℃. As far as the reduction of ZnO was concerned, it was controlled by interfacial chemical reaction when the reduction temperature was between 950～1100℃.On a basis of investigations of preparation, drying, preheating and roasting characteristics of tin, zinc-bearing iron concentrate pellet, a new process of comprehensive utilization of tin, zinc-containing iron concentrate by weak reduction roasting was fast put forward. Technological parameters of the scale-up experiment were performed on an analog equipment of a grate-kiln. Under the optimal experimental conditions, 1～2% anthracite, which was added inside the pellets, had a little effect on the volatiliTation of tin and zinc. Compared with the pellets without internal anthracite, the volatilization rate of tin and zinc was improved by 0.5～1.5%, which was respectively more than 80% and 70%, and the remaining contents of tin and zinc in the roasted pellets were less than 0.06%. The compression strength of the finished pellets was in excess of 2480 N/P, the ISO tumbling index over 97% and the abrasion index less than 2%. The results obtained from scale-up experiments showed that the new process could effectively realize the separation of tin and zinc from iron. The compression strength of roasted pellets and residual tin and zinc in them also met the requirement of the blast furnace production.The factual acreages of all the main minerals in the artificial pellets were measured by using Leica Figure Analytical Software—Qwin. By the application of optical microscope, SEM, XRD and X-ray energy spectrograph, the main minerals were approved and the factual mass percentage of them in. the roasted pellets were calculated based on the chemical analytical results. From the above research, the bonding mechanism of the pellets by weak reduction roasting was performed for the first time. The investigations disclosed that the weak reduction roasted pellet was mainly bonded by the recrystallization of wustite at high temperature, and the wustite particles were connected with each other and incrusted closely by the olivine crystallized imperfectly between them. So the pellets have high strength.This investigation provided a new approach for the comprehensive utilization of fin, zinc-bearing complex iron concentrate and credible technological parameters for the industrial production of the new process.更多还原