Composite Pellets – A Potential Raw Material for Iron‐Making

Abstract

Coke constitutes the major portion of iron-making cost and its production causes severe environmental concerns. In addition, lower energy consumption, lower CO 2 emission and waste recycling are driving the Iron and steel making industry to develop "coke free, zero waste or green processes". In the present article, an overview of possible ways to recognize a reasonable improvement in iron and steel making industry is summarized. The present discussion is focusing on the following approaches;1. Replacing expensive coke with relatively less expensive alternate fuels having carbon as well as significant amount of hydrogen such as coal, waste plastic and biomass materials. 2. Producing agglomerates from cheaper raw materials (secondary resources) as well as improving their performance in BF. 3. Making the process towards higher carbon utilization by shifting the wustite equilibrium towards lower CO/CO 2 ratio by using high reactive coke or catalytic activated one. 4. Recycling the unused CO in the top gas by removing CO 2 from the gas stream.Much attention has been paid to carbon composite agglomerates (CCA) as a promising raw material for future iron making. Production, mechanical and chemical suitability, reduction behavior, etc. are being elaborated. In addition, other possible ways to utilize CCA in alternate iron-making process has been explored.

Novel Approach Towards Biomass Lignin Utilization in Ironmaking Blast Furnace

“…The factors affecting the reduction kinetics and mechanisms of iron ore carbon agglomerates have been thoroughly discussed elsewhere. 27) …”

Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere

“…At and above 770°C the reaction mechanism is believed to change which is indicated by the sloop discontinuity of TG curves. Based on an earlier investigation by the authors, 15) it is believed that reduction of magnetite and wustite is carried out above 770°C. The change of reaction from reduction of magnetite to wustite reduction is indicated by the sudden increase in the reaction rate wich is attributed to the presence of metallic iron.…”

Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

“…This is likely to be the reason for high reaction initiation temperature compared to the reduction of magnetite by a reducing gas. [1] Due to the physicochemical changes that happen as a consequence of the reduction reaction, composite pellet showed a remarkable shrinkage. This is due to the sintering of unreacted oxides and metallic product that take place under the driving force of decrease in the total surface energy of the system.…”

“…[1] These reduction reactions are highly endothermic and hence, the overall rate of these reactions is greatly influenced by the heat transfer through powder mixture. Therefore, in such processes, the knowledge of the effective thermal conductivity of the composite pellet made of powder mixture is essential for process understanding and control.…”

“…This oxygen might react with solid carbon to produce CO (Eq. [1]). However, under the present experimental conditions, this is not likely to be the case in view of the system being evacuated and flushed with argon before the start of the experiments.…”