【作者】 徐萌；

【导师】 张建良；

【作者基本信息】 北京科技大学 ， 钢铁冶金， 2006， 博士

【摘要】 随着对环境保护的日益重视以及对成本控制的需要,炼铁工业的改革势在必行。对用铁精矿粉取代烧结矿,用煤取代焦炭的直接还原和熔融还原炼铁工艺的研究正越来越蓬勃兴旺。转底炉煤基热风熔融炼铁工艺,又称恰普法(Coal Hot-Air Rotary Hearth Furnace Process,简称CHARP)是20世纪九十年代末由北京科技大学冶金学院冶金喷枪研究中心在转底炉直接还原基础上开发的新炼铁工艺。该工艺以矿粉煤粉复合含碳球团为原料,在1350~1450℃的温度下,使得球团快速还原,经渣铁熔分,得到形似珠状、成分如生铁、不含脉石的产品,称为珠铁,而不同于一般的金属化球团。本文主要为该工艺的基础研究,目的是充分地掌握含碳球团还原熔分的特点、机理以及所需要的一般性条件。因此利用高温电阻炉对转底炉内含碳球团还原、熔分行为进行了热态模拟,并且对含碳球团还原、熔分过程中硫的分配、硫的行为及如何控制或者降低珠铁中的硫含量进行了实验研究。然后又将研究对象扩展到普通铁矿粉之外的特殊铁矿,特别是对钒钛磁铁矿、钛精矿复合含碳球团的还原熔分行为进行了探索性的研究,既扩大了转底炉煤基热风熔融炼铁工艺对矿的适用范围,又为钛资源利用开辟了新的方法。在确定含碳球团还原熔分的基本参数后,针对工业转底炉原型,利用CFX软件,耦合湍流、燃烧和辐射模型,对转底炉炉内湍流流动、燃烧和传热进行了数值模拟研究,得到了炉膛内温度场和流场的分布。本研究的主要创新点表现在:(1)对转底炉煤基热风熔融炼铁工艺进行了高温热态模拟,研究了含碳球团的还原熔分的行为以及还原熔分过程中的硫行为及硫控制。(2)提出了通过转底炉利用钛资源的两条路线,并通过实验证实了这两条路线的技术可行性。一是以钒钛磁铁精矿为主要原料,以Na2SO4为熔剂,经过还原熔分后得到铁和品位约50%的含钛渣,二是以钛精矿为原料,以Na2SO4和Li2CO3为复合熔剂,经过还原熔分和磁选后得到当量直径3~8毫米的粒铁和品位约75%的含钛渣。(3)根据热态模拟实验的结果,对转底炉内燃烧、传热、流动现象进行了数值模拟,得到了转底炉料面层的温度场和流场的分布,为工程化设计提供参考和依据。更多还原

【Abstract】 For environmental and economic consideration, it is necessary for ironmaking industry to use iron ore concentrates and coal directly instead of coking and sintering. So the research and development of the smelting reduction process are being paid more and more attention. The Coal Hot-Air Rotary Hearth Furnace Process (CHARP) has been developed by University of Science and Technology Beijing since 1997, which is a new iron-making process evolved from the direct reduction of ore/coal composite pellets in rotary hearth furnace (RHF). At the temperature of 1350℃ to 1450℃, iron oxides in pellets are reduced by coal to iron. After carburization, melting and separation between liquid iron and slag components, iron bead without gangue can be formed, which is different from direct reduced iron (DRI). The present work mainly concentrates on a fundamental study on the CHARP process by thermal simulation experiment. The behavior of the reduction and melting in ore/coal composite pellets has been investigated at high temperature, as well as the distribution of sulfur and the behavior of sulfur during the reduction, melting and separation of pellets have been studied. Methods how to decrease or control the sulfur content in iron bead have been proposed. During the experimental process, a series of samples have been taken for chemical analysis in the partially or completely reacted specimens. These results have brought about a better understanding of the reduction process at high temperature. In order to the comprehensive utilization of titanium resource, the reduction and melting in vanadium titano-magnetite/coal or ilmenite/coal composite pellets have been studied in the laboratory. A new process and two routes on titanium resource utilization have been put forword. By the numerical simulation on the turbulent flow, combustion and radiative heat transfer in rotary hearth furnace (RHF), the distribution of temperature and flow in the furnace has been determined. The main new viewpoints of the author are as follows: The reduction of iron oxides, melting and separation of iron and slag in pellets have been investigated at the temperature of 1350℃ to 1450℃. The behaviour of sulphur and the control of sulphur during the reduction and melting process in pellets have been investigated. The research on the beneficiation of titanium oxides from Panzhihua ilmenites by means of the reduction of coal bearing pellets has been carried out. Two routes of utilizing the titanium resource by RHF are proposed: one is to produce iron bead and slag containing about 50 percent titanium oxides after the reduction and melting of vanadium titano-magnetite concentrates with sodium sulfate as the flux; while another is to produce the slag containing about 75 percent titanium oxides and granular iron with sodium sulfate and lithium carbonate as the composite flux. The size of granular iron is ranged from 3 millimeter to 8 millimeter after reduction, melting and magnetite separation. The temperature field and flow field in RHF have been calculated by using CFX software, which would be helpful for engineering design.更多还原