Tiara Triana, Geoffrey A. Brooks, M. Akbar Rhamdhani, Mark I. Pownceby
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A thermodynamic assessment using FactSage 8.2 thermochemical software was carried out examining the behavior of ammonia gas as the reductant upon heating, detailed evaluations of the stable phases present under different reaction conditions and using different feed materials, and the formation and stability of iron nitride phases. The results suggest that the reduction of hematite with ammonia occurs in two steps below 570 °C and three steps above 570 °C. The ratio of Fe<sub>2</sub>O<sub>3</sub>/NH<sub>3</sub> was predicted to affect the reduction reactions by promoting a greater reduction degree and simultaneously lowering the initial temperature needed for reduction, while the excess gas concentration can suppress FeO formation. A predominance area diagram was developed showing the main areas of stable phases as a function of the partial pressure of NH<sub>3</sub> and temperature. The formation of iron nitrides during the process was predicted and these were not expected to cause issues for the formation of iron due to their instability under the conditions studied. This analysis can be used to inform further experimental studies regarding ammonia reduction of iron oxide.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\n","PeriodicalId":17160,"journal":{"name":"Journal of Sustainable Metallurgy","volume":null,"pages":null},"PeriodicalIF":2.5000,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Iron Oxide Direct Reduction and Iron Nitride Formation Using Ammonia: Review and Thermodynamic Analysis\",\"authors\":\"Tiara Triana, Geoffrey A. Brooks, M. Akbar Rhamdhani, Mark I. 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The formation of iron nitrides during the process was predicted and these were not expected to cause issues for the formation of iron due to their instability under the conditions studied. 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引用次数: 0
摘要
钢铁行业是全球温室气体排放的主要贡献者之一,约占全球总产量的 7% 至 9%。焦炭是将富含铁的原料还原成铁的主要方法,钢铁行业面临着通过减少焦炭消耗实现净零排放的压力。由于氨具有完善的合成工艺、高度的供应链、直接的处理技术和高度发达的长期基础设施,氨有可能成为焦炭的替代品,成为未来的铁矿石还原剂。本研究回顾了之前关于氨直接还原氧化铁以及可能形成氮化铁的研究。使用 FactSage 8.2 热化学软件进行了热力学评估,检查了氨气作为还原剂在加热时的行为,详细评估了在不同反应条件下和使用不同进料时出现的稳定相,以及氮化铁相的形成和稳定性。结果表明,赤铁矿与氨气的还原反应在 570 °C 以下分两步进行,在 570 °C 以上分三步进行。据预测,Fe2O3/NH3 的比例会影响还原反应,促进更大的还原度,同时降低还原所需的初始温度,而过量的气体浓度则会抑制 FeO 的形成。根据 NH3 分压和温度的函数关系,绘制出了显示主要稳定相区域的优势区域图。预测了工艺过程中氮化铁的形成,由于在研究条件下氮化铁的不稳定性,预计这些氮化铁不会对铁的形成造成问题。这一分析可为氨还原氧化铁的进一步实验研究提供依据。
Iron Oxide Direct Reduction and Iron Nitride Formation Using Ammonia: Review and Thermodynamic Analysis
The steel industry is one of the main contributors to global greenhouse gas emissions, responsible for about 7 to 9% of the world’s total output. The steel sector is under pressure to move toward net-zero emissions by reducing its consumption of coke as the main method of reducing iron-rich feed materials to iron. Due to its well-developed synthesis process, high supply chain, straightforward handling technologies, and highly developed long-standing infrastructure, ammonia has the potential to become a replacement for coke as a future iron ore reductant. This work reviews previous research on ammonia direct reduction of iron oxides and the possible formation of iron nitrides. A thermodynamic assessment using FactSage 8.2 thermochemical software was carried out examining the behavior of ammonia gas as the reductant upon heating, detailed evaluations of the stable phases present under different reaction conditions and using different feed materials, and the formation and stability of iron nitride phases. The results suggest that the reduction of hematite with ammonia occurs in two steps below 570 °C and three steps above 570 °C. The ratio of Fe2O3/NH3 was predicted to affect the reduction reactions by promoting a greater reduction degree and simultaneously lowering the initial temperature needed for reduction, while the excess gas concentration can suppress FeO formation. A predominance area diagram was developed showing the main areas of stable phases as a function of the partial pressure of NH3 and temperature. The formation of iron nitrides during the process was predicted and these were not expected to cause issues for the formation of iron due to their instability under the conditions studied. This analysis can be used to inform further experimental studies regarding ammonia reduction of iron oxide.
期刊介绍:
Journal of Sustainable Metallurgy is dedicated to presenting metallurgical processes and related research aimed at improving the sustainability of metal-producing industries, with a particular emphasis on materials recovery, reuse, and recycling. Its editorial scope encompasses new techniques, as well as optimization of existing processes, including utilization, treatment, and management of metallurgically generated residues. Articles on non-technical barriers and drivers that can affect sustainability will also be considered.