Granulation behavior and strengthening strategy of iron ore blends containing specular hematite concentrate
摘要
Specular hematite concentrate, characterized by predominantly intermediate particle size distribution with minimal ultrafine fractions and a dense, smooth surface texture, exhibits poor granulation performance, resulting in a significantly lower proportion in sinter mixtures. The granulation behavior of iron ore blends containing 40% Canadian specular hematite concentrate was systematically investigated, focusing on the effects of nuclei types, adhering fines and binders on the packed bed permeability and adhesion load, and solutions were developed for improving its granulation performance. The results revealed that the granulation effectiveness of specular hematite concentrate is influenced more significantly by the type of adhering fines than by the type of nuclei. Specifically, adhering fines with higher maximum molecular moisture content (e.g., goethite-type LO-F) and elevated proportions of −0.01 mm ultrafine particles help improve the adhering performance, while particles with higher microhardness (e.g., magnetite MO-F) hinder adhesion. The addition of quicklime and bentonite as binders further enhances the adhesion, and the specular hematite concentrate adhesion load increases by 4.4% with a combination of quicklime and bentonite, accompanied by 33% enhancement in packed bed permeability. An optimized strategy recommends selecting adhering fines with high molecular water content and low microhardness, combined with binders, to improve sintering efficiency and support low-carbon ironmaking transitions.