Method for reducing fuel consumption and greenhouse gases in an iron ore traveling grate furnace

Minerals & Metallurgical Processing , 2012, Vol. 29, No. 3, pp. 137-143

Clements, B.; Pomalis, R.; Zheng, L.; Herage, T.; Godin, E.

ABSTRACT:

A study was carried out by CanmetENERGY and ArcelorMittal Mines Canada (AMMC) to investigate the feasibility of reducing fuel consumption and greenhouse gas (GHG) emissions in an Outotec (previously Dravo-Lurgi) traveling straight grate induration furnace using flue gas recirculation. The concept was developed to reduce excess air requirements in the furnace by replacing a fraction of the air with recycled flue gas, while maintaining similar mass flow rates across the pellet bed. By retrofitting and operating the furnace in this manner, the convective heat transfer rates within the furnace could be maintained at typical operating levels. The application of this technique significantly improves the thermal efficiency of the unit, thereby reducing fuel consumption and GHG emissions. Computer simulation was performed on three different flue gas recycle retrofit scenarios using an AspenTech HYSYS process model and an in-bed model (SIMBOUL) that models the operating characteristics of the pellet bed and predicts product quality. The computer simulation was validated using plant operating data and field measurements from the two induration machines at AMMC’s processing plant in Port Cartier, Quebec. It was found that significant fuel savings could be achieved with many of these different retrofit options. One option reduced the No. 6 fuel oil used by 46%. Results from the models suggest that, while the major product quality indices remain unchanged, the average product discharge temperature increases with many of the options considered. This concern must be examined further.