The Preparation and Reduction Behavior of Charcoal Composite Iron Oxide Pellets

Abstract

In the energy conversion, biomass has novel advantage, i.e., no CO₂ emission, because of carbon neutral. Charcoal composite iron oxide pellets were proposed to decrease CO₂ emission for the ironmaking. These pellets were promising to decrease the initial temperature for reduction reaction of carbon composite iron ore agglomerate under a rising temperature condition, such as in a blast furnace shaft. In order to obtain charcoal, Japanese cedar and cypress were carbonized from room temperature to maximum carbonization temperature (T_{C, max} = 1273 K) at a heating rate of 200 K/h, and kept at T_{C, max} until arrival time of 6 h. Reducing gases of CO and CH₄ started releasing from relatively low temperature (500 K). In the total gas volume of carbonization, H₂ gas of Japanese cedar was more than that of Japanese cypress. These woods have more CO gas volume than Newcastle blend coal has. The obtained charcoal was mixed with reagent grade hematite in the mass ratio of one to four. Then, a small amount of Bentonite was added to the mixture as a binder, and the charcoal composite iron oxide pellets were prepared and reduced at 1273, 1373 and 1473 K in nitrogen gas atmosphere. It was conirmed by the generated gas analysis during reduction reaction that charcoal composite iron oxide pellets had higher reducibility than char composite pellets using Newcastle blend coal. From the XRD analysis of the reduced pellets, it was found that the original Fe₂O₃ was almost reduced to Fe for 60 min at 1273 K, 20 min at 1373 K and 5~15 min at 1473 K.