Abstract

The use of biomass in different routes of ironmaking has been recently investigated. Although the volatile matter is the major constituent of the biomass, its contribution as reducing agent has not been explored in detail. This work aimed to investigate the reduction of iron ore by biomass volatiles and elucidate the steps involved, searching for optimization of its use in the ironmaking industry. Experiments with biomass and iron ore packed beds placed separately were carried out in the interval between 200 and 1000 °C in an infrared furnace. Iron ore reduction was observed at low temperatures (< 800 °C) and increased up to 1000 °C, where wustite, metallic iron and cementite were detected by XRD. Carbon deposition at low temperatures and carbothermic reduction at high temperatures were identified through carbon analysis and thermal profile measures. At low temperature the reduction occurred mainly by the non-condensable gases (CO, H₂) from biomass pyrolysis and tar cracking reactions, while from 800 °C the reduction advanced by carbon deposited on the iron ore. The activation energy for the carbothermic reduction indicated the carbon gasification as the reaction-limiting step. The deposited carbon proved to be more reactive than other carbon sources commonly used in the ironmaking.

Graphical Abstract

中文翻译：

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生物质挥发物减少铁矿石

摘要

最近已经研究了生物质在炼铁的不同途径中的使用。尽管挥发性物质是生物质的主要成分，但尚未详细探讨其作为还原剂的作用。这项工作旨在调查生物质挥发物对铁矿石的还原作用，并阐明其中涉及的步骤，以寻求在炼铁行业中对其使用的优化。将生物质和铁矿石填充床分开放置的实验是在200到1000°C的红外炉中进行的。在低温（<800°C）下观察到铁矿石还原，并在高达1000°C的温度下还原，在XRD上可以检测到钙铁矿，金属铁和渗碳体。通过碳分析和热曲线测量可确定低温下的碳沉积和高温下的碳热还原。在低温下，还原主要由不可冷凝气体（CO，H₂）来自生物质的热解和焦油裂解反应，而从800°C开始，还原由于碳沉积在铁矿石上而加速。碳热还原的活化能表明碳气化是反应限制步骤。事实证明，沉积的碳比炼铁中常用的其他碳源更具反应性。

图形概要