Improvement on the thermal cracking performance of pellets prepared from ultrafine iron ore

As the ultrafine iron ore concentrate was used to prepare green pellets, the main problem was the serious cracking during the drying process. The fine particles contacted so closely that the porosity of green pellet was only 16.68%, which finally hindered vapor diffusion, and the cracking temperature was only 370 degrees C. Organic binder replacing parts of bentonite improved the cracking temperature to 500 degrees C, with comparable mechanical strength. Due to the action of organic binder, fine-grained concentrates were aggregated into large particles, with the porosity of green pellet increased from 16.68% to 23.15%. Furthermore, the average drying rate decreased, which dropped from 0.55 g.kg(-1). s(-1) to 0.47 g.kg(-1).s(-1). Consequently, the vapor pressure of the green pellet in the dry front was reduced, which successfully improved the cracking property. (C) 2018 Elsevier B.V. All rights reserved.