Contents lists available at ScienceDirect Fuel Processing Technology journal homepage: www.elsevier.com/locate/fuproc Research article Reduction of mild-dehydrated, low-grade iron ore by ethanol Ade Kurniawan, Keisuke Abe, Kouichi Ohashi, Takahiro Nomura, Tomohiro Akiyama ⁎ Center for Advanced Research of Energy and Materials, Hokkaido University, North 13 West 8, Kita-ku, Sapporo 060-8628, Japan ARTICLE INFO Keywords: Ethanol Goethite Porous iron ore Reduction Ironmaking ABSTRACT Low-grade iron ore with high combined water (CW) content (e.g., goethite) has been first dehydrated at low temperatures mildly to be slit-shaped nano-order pore, then has been reduced by ethanol (C 2 H 5 OH) charging under the heating conditions. Bioethanol as derived from biomass, regarded as a renewable and carbon-neutral resource, is a promising candidate as a reducing agent for ironmaking. In the experiments, ethanol was dropwise added to the mild-dehydrated, porous iron ore beds at heating conditions using the temperature-program. As a result, the ethanol was soon decomposed to CO and H 2 , which then reduced the iron oxides. Porous iron ore acts as a good catalyst for ethanol decomposition as it simultaneously reduces to metallic iron. Interestingly, iron oxides were reduced at a lower temperature, compared to conventional coal-based ironmaking in the blast furnace. Metallic Fe was obtained at only 750 °C, showing a reduction degree of 81%, due to the contribution of hydrogen reduction. The longer charging time of ethanol promotes the higher reduction degree as well as suf- ficient compositions of reducing gas (H 2 -CO) for the reduction process. The results of experiments using different iron ores revealed the general rule that the higher CW content in ore makes the larger surface area of the iron ore by mild-dehydration, causing higher reactivity in the reduction process. The results appealed that mild-dehy- drated iron ore is good raw materials of bioethanol ironmaking, due to its nanopores. 1. Introduction Recently, numerous methods have been proposed to reduce carbon dioxide emissions in the ironmaking process. The Paris Agreement (2015) requires the implementation of several actions on climate change mitigation by reducing greenhouse gas emissions [1]. One of the most challenging problems for reducing carbon dioxide emissions is to replace non-renewable carbonaceous materials such as coke as the re- ducing agent in ironmaking. Another difficult challenge is to improve the reactivity of iron ore and the reducing agent, resulting in the op- portunity to perform faster and lower-temperature reduction processes. In the case of blast furnaces, the temperature of the thermal reserve zone, where the temperature is 1000 °C, is determined by the reaction rate of coke gasification by carbon dioxide; this prevents the effective use of the reducing agent [2]. Thus, one of the most effective solutions to improve reactivity is to place composites of the iron ore and carbon in close contact with each other [3–6]. On the other hand, to overcome the abundance trend of low-grade iron ore (i.e., goethite) over hematite/magnetite ore, an innovative solution is required. A new ironmaking method known as chemical vapor infiltration (CVI) ironmaking using a renewable carbonaceous material such as biomass together with nanoporous hematite ore was proposed [7]. This process requires three steps to reduce the iron ore. The first step is the dehydration process of the combined water (CW) contained in the goethite in high amounts, e.g., 8.8 mass% in lower temperature (so-called mildly-dehydration), to change the goethite ore structure to nanoporous hematite ore [8]. The second step is the car- bonization process of the porous iron ore to invoke the simultaneous mechanisms of pyrolysis, catalytic tar decomposition, and carbon de- position through CVI in one integrated process [9–13]. The deposited carbon structure, detected as amorphous carbon, provides higher re- activity for the reduction process [14]. Infiltration of carbon into the ore pores improves not only the reactivity of the iron ore but also its mechanical strength [15]. During tar decomposition and carbon de- position in iron ore, the iron ore structure changes from hematite to magnetite (or even wüstite), meaning the reduction occurs; that is called pre-reduction processes [16]. However, because pre-reduction produces mainly the magnetite structure, the reduction degree (RD) is only approximately 11% [17]. Thus, it requires a third step, which is the reduction process to reach metallic Fe (RD 100%) [18]. Narrowing the large gap of RD from 11% to 100% by increasing the RD from the pre-reduction process has aroused much research interest. By focusing on the improvement of the pre-reduction mechanism, CVI technology might become more attractively applicable. One approach is to introduce a small-molecule carbonaceous ma- terial such as ethanol as the reducing agent in porous hematite ore. As a https://doi.org/10.1016/j.fuproc.2018.05.034 Received 13 March 2018; Received in revised form 23 May 2018; Accepted 25 May 2018 ⁎ Corresponding author. E-mail address: takiyama@eng.hokudai.ac.jp (T. Akiyama). Fuel Processing Technology 178 (2018) 156–165 0378-3820/ © 2018 Elsevier B.V. All rights reserved. T