Molecular Dynamics Simulation: Influence of External Electric Field on Bubble Interface in Air Flotation Process

Emerging Trends of Computational Chemistry and Molecular Modeling in Froth Flotation: A Review

Froth flotation is the most versatile process in mineral beneficiation, extensively used to concentrate a wide range of minerals. This process comprises mixtures of more or less liberated minerals, water, air, and various chemical reagents, involving a series of intermingled multiphase physical and chemical phenomena in the aqueous environment. Today's main challenge facing the froth flotation process is to gain atomic-level insights into the properties of its inherent phenomena governing the process performance. While it is often challenging to determine these phenomena via trial-and-error experimentations, molecular modeling approaches not only elicit a deeper understanding of froth flotation but can also assist experimental studies in saving time and budget. Thanks to the rapid development of computer science and advances in high-performance computing (HPC) infrastructures, theoretical/computational chemistry has now matured enough to successfully and gainfully apply to tackle the challenges of complex systems. In mineral processing, however, advanced applications of computational chemistry are increasingly gaining ground and demonstrating merit in addressing these challenges. Accordingly, this contribution aims to encourage mineral scientists, especially those interested in rational reagent design, to become familiarized with the necessary concepts of molecular modeling and to apply similar strategies when studying and tailoring properties at the molecular level. This review also strives to deliver the state-of-the-art integration and application of molecular modeling in froth flotation studies to assist either active researchers in this field to disclose new directions for future research or newcomers to the field to initiate innovative works.

Effect of an Electric Field on Surface Properties of Hydrophobic Particles during a Flotation Process in Salt Water

Under air flotation conditions, the effect of an electric field (EF) to the interfacial properties of hydrophobic particles in salt solution was investigated by using molecular dynamics simulation. The varieties of thickness of the hydrophobic layer on the surface of the hydrophobic particles, radial distribution function of Na⁺, diffusivity of CO₂ and H₂O, residence time of H₂O in the solvent shell of Na⁺, and the distribution of CO₂ near the graphene caused by the applied EF in different NaCl systems were calculated, and all those results were compared with those where there is no EF applied. The results reveal that the thickness of the hydrophobic layer near the hydrophobic particles is decreased under an EF. The coordination number and residence time of H₂O in the solvent shell of Na⁺ are also decreased, which indicates that the restraint of Na⁺ on surrounding H₂O is weakened, and the H₂O molecules are more mobile. Under an external EF, the diffusion coefficient of CO₂ and H₂O is increased, and the quantity of CO₂ near the surface of graphene is decreased according to the numerical results of the radial distribution of graphene-CO₂. All the results indicate that the EF will decrease the thickness of the hydrophobic layer near hydrophobic particles, which can therefore weaken the adsorption between the hydrophobic particles and the gas molecules. The simulation results in the present study can provide theoretical support for brine mineral flotation under an external EF.