ABSTRACT

Carbon is used in the hematite ore pellet as a partial heat source for induration. Apart from this, it has several other roles in the pellet. To achieve the maximum benefit of carbon in pellet quality improvement and energy reduction, a detailed study on the mechanism of C reaction in hematite pellets is required. Although some investigators have reported improvement in pellet properties on using carbon, its detailed analysis is still lacking. For this, the study on the reaction mechanism during induration is essential, which has not been done so far. To alleviate the above knowledge gap, the reaction mechanism of in-situ carbon has been studied through thermodynamic analysis and experimentation in this work. The possibility of evolving carbon monoxide and carbon dioxide during the burning of carbon at the initial stage has been analyzed from the thermodynamic study. The produced carbon monoxide gas may partially reduce the iron oxides in the pellet. This in-situ reduced iron oxide may be beneficial in the sintering of pellets. The possibility of reduction of ferric oxide in pellets followed by its re-oxidation in the final stage has been studied thermodynamically and experimentally. This study helps to understand the mechanism of in-situ carbon reaction during induration and its role in improving the quality of pellets and reducing energy consumption. It is found that the use of carbon enhances diffusion bonding in acidic pellets and both diffusion and slag bonding in basic pellets. The use of 1.5% carbon reduces the induration temperature by 50 K.

摘要

赤铁矿球团中使用碳作为硬化的部分热源。除此之外，它在颗粒中还有其他几个作用。为了使碳在提高球团质量和降低能耗方面发挥最大效益，需要对赤铁矿球团中碳反应的机理进行详细研究。尽管一些研究人员报告了使用碳在颗粒性能方面的改进，但仍缺乏对其的详细分析。为此，对硬结过程中的反应机理的研究是必不可少的，目前还没有研究过。为了弥补上述知识空白，本工作通过热力学分析和实验研究了原位碳的反应机理。通过热力学研究分析了碳在燃烧初期产生一氧化碳和二氧化碳的可能性。产生的一氧化碳气体可以部分还原球团中的铁氧化物。这种原位还原的氧化铁可能有利于球团的烧结。已经通过热力学和实验研究了球团中氧化铁还原然后在最后阶段再氧化的可能性。本研究有助于了解硬结过程中原位碳反应的机理及其在提高球团质量和降低能耗方面的作用。发现碳的使用增强了酸性球团中的扩散结合以及碱性球团中的扩散和熔渣结合。使用 1.5% 的碳可将硬化温度降低 50 K。