The role of amylose and amylopectin in selective flocculation of iron ore slimes

With the depletion of high-grade iron ore reserves, starch-based selective flocculation has proven to be an effective technique for processing ultrafine iron ore particles. Here, molecular modelling has been employed to examine the adsorption mechanism of starch polymer components, amylose and amylopectin, on hematite and goethite as well as gangue minerals of quartz and kaolinite. Through the DFT method, this research clarifies the contribution of amylose and amylopectin to the flocculation selectivity of starch by adsorbed polymer geometry as well as adsorption energies on the surfaces of each mineral. The obtained results illustrates that the amount of absorption energy of amylose on both hematite and gangue minerals is higher than that of amylopectin, and the amount of absorption energy obtained for both amylose and amylopectin in the case of hematite and goethite is significantly higher than that of quartz and kaolinite (Al-OH end). The results suggest that both amylopectin and amylose play the role in the selectivity of flocculants, which contrasts with earlier studies that attributed the selectivity of starch solely to amylose. The Fe-O chemical bond acts as the primary interaction mechanism linking the starch components with both hematite and goethite, while a considerably weaker hydrogen bond supports the interaction between kaolinite and amylose.