Molecular modelling applied to the flotation of iron ores

Iron is one of the most exchanged commodities worldwide. Its use for steelmaking explains the growing demand in the metal which remains mainly produced by the mining and the beneficiation of iron ores. Flotation is the most used mineral separation technique worldwide, processing several billion tonnes (Bt) of ore annually, including, in some cases, hematite and magnetite ores. Based on the physicalchemical properties of mineral surfaces, flotation aims to selectively adsorb molecules that render mineral surfaces either hydrophobic or hydrophilic, known as collectors and depressants, respectively. Hydrophobic particles are then recovered in the froth by the injection of gas bubbles travelling up in the cell and attaching the hydrophobic particles. However, despite the popularity and the good performances of flotation, mining industry faces new challenges of decreasing grades and increased mineralogical complexness in ores. Many flotation variables, especially when related to reagent adsorption, remain poorly understood and it becomes necessary to gain knowledge to enhance the existing processes. Molecular modelling techniques like the density functional theory or molecular dynamics simulations (ie Classical molecular dynamics or Ab initio Molecular Dynamics) currently represent powerful tools for different applications in material sciences, like catalysis or depollution purposes. They have recently been successfully applied in the flotation area, with an increasing number of publications dealing with this topic every year. These tools provide crucial information on bulk and surface properties as well as on the adsorption mechanisms of reagents on mineral surfaces, key step in the flotation process, and synergetic effect of collector mixtures. A better understanding of the adsorption mechanisms of flotation reagents, provided by molecular simulations, will help to finely choose flotation reagents, and even lead to the development of new reagents formulations. Overall, these tools enable the discovery of practical and industrial solutions to improve the flotation process, which will undoubtedly help the mining industry to face its future challenges.