基于全氧富氢炼铁新工艺的焦炭劣化机理研究

Reducing the energy cost and pollution in the traditional ironmaking process of blast furnace has reached its limitation. Japan and the EU have lauched intensive study on the new oxygen blast furnace process as well as the injection of hydrogen fuel.The new process can provide gas with a high caloricity and a low N2 content.It is benefical for recycling CO2 and achieving the target of zero CO2 emissions. The atmospheric haze caused by coal-fired in iron-making process can be greatly relieved because the new process can take full advantage of the gasification capabilities of blast furnace, the desulfurization capacity of slag and the purification capacity of gas. Meanwhile, the H2 content in furnace hearth gas and the amount of water vapor in the belly and the lower stack of BF can be raised significantly in the new process. Therefore, this study will focus on the following topics: the reaction of coke with furnace gas that contain H2O, CO2 and the consequnt solution loss of coke; the influence of water vapor and CO2 on the coke degradation. Based on these work we will establish the relations between the microstructure and the solution loss damage of coke and propose suitable evaluation for coke in the new hydrogen-rich and full oxygen blast furnace process. We will also study the influence of H2, CO and the mixed gas on the reduction of iron ore and influence of pre-reduction rate of ore and coke reactivity on the dripping properties of ore and coke solution loss. The coupling effect of reduction of iron ore and coke gasification reaction will be explained. Based on this research the optimal amount of hydrogen injection and the optimal properies of raw fuel pyrometallurgical will be determined for the new process.

传统高炉炼铁工艺的节能减排潜力已很有限，日本、欧盟已开展全氧高炉、喷吹含氢燃料高炉新工艺研究。该工艺可以提供高热值煤气，煤气N2含量低，有利于CO2回收，实现CO2零排放。该新工艺可充分利用高炉煤气化能力、炉渣脱硫能力以及煤气净化能力，减少燃煤带来的大气雾霾。同时该新工艺大幅度提高了炉缸煤气中H2含量和炉腰炉身下部水蒸气量。为此，本研究拟通过研究H2O、CO2及混合气体与焦炭溶损深层反应，解明水蒸气、CO2对焦炭劣化影响规律，揭示焦炭劣化与微观结构关系，确立适合全氧富氢高炉新工艺的焦炭评价方法；通过研究H2、CO及混合煤气对铁矿石还原及焦炭劣化影响规律，矿石预还原率、焦炭反应性对矿石熔滴性能与焦炭溶损特性影响规律，解明炉内铁矿石还原和焦炭气化反应的耦合效应，为新工艺确立适宜的富氢量和适宜的原燃料高温冶金性能提供依据。

全氧喷吹含氢燃料高炉新工艺必然是高炉炼铁发展趋势，其主要目的就是低碳冶炼、低CO2排放，该新工艺将大幅度提高炉缸煤气中 H2 含量，因此炉腰炉身下部等高温区煤气必然将含有大量水蒸气与CO2。传统焦炭在高炉内劣化、粉化主要是与CO2气化反应造成的，因此全氧喷吹含氢燃料高炉焦炭劣化也就必将是焦炭与 H2O、CO2及混合气体的气化反应所致。本项目开展了基于全氧富氢炼铁新工艺的焦炭劣化机理研究，研究焦炭与水蒸气、CO2在不同温度下反应的气化速率、热态性能变化，焦炭与水蒸气、CO2气化反应开始温度、激烈温度，焦炭与水蒸气、CO2反应的限制性环节和反应活化能；研究焦炭与水蒸气、CO2深层反应后焦炭内部径向各部位微观形貌、气孔孔径分布、密度和光学组织变化，揭示焦炭劣化与微观结构关系，进而阐明焦炭劣化的微观演变机制。研究了K/Na对焦炭与水蒸气、CO2反应的气化速率、热态性能变化的影响，对焦炭与水蒸气、CO2气化反应开始温度、激烈温度的影响，对焦炭与水蒸气、CO2反应的限制性环节和反应活化能的影响，阐明了K/Na催化焦炭与水蒸气、CO2气化反应的机理。研究传统高炉条件和全氧富氢条件下焦炭气化与铁矿石还原耦合反应，研究反应温度、矿焦比、反应气氛对焦炭溶损率、反应后强度以及铁矿石还原度的影响。以不同预还原度铁矿石的熔滴性能为研究对象，研究了预还原度对烧结矿软化开始温度TA、软化终了温度TS、滴落温度TM、最大压差ΔPMax、软化温度区间ΔTSA及软熔温度区间ΔTMS的影响。本项目为全氧富氢炼铁新工艺提供了理论和技术支持，共发表学术论文10篇，其中SCI/EI收录5篇，CSCD收录3篇；申请国家发明专利3项，授权3项。