Effect of inorganic cations on enhancing graphite/kerosene adsorption and reducing carbon emission in graphite flotation

Understanding the effect of inorganic cations on the adsorption of kerosene droplet at graphite surface is a prerequisite to predict the graphite flotation. Using a high-speed motion acquisition system, the contact angle, kerosene droplet size and three phase contact line (TPC line) were explored. The equivalent diameter of the kerosene droplet increased until 10 -2 mol/L and then decreased slightly with increasing the concentration of NaCl and MgCl 2 . On contrary, the equivalent diameter showed an opposite trend in the presence of AlCl 3 . The final TPC line followed the order: AlCl 3  < MgCl 2  < NaCl at an ion concentration 10 -2 mol/L. Through the simulation of radial distribution function (RDF) via the Material studio software, the oxygen atom was more easily attracted than the hydrogen atom by Na + , resulting in the smallest kerosene droplet-graphite block contact angle in the presence of NaCl. Furthermore, NaCl and MgCl 2 presented an opposite trend to AlCl 3 in the solution/kerosene interfacial tension. Our results matched the cation hydration at different pH. The subsequently conducted graphite flotation showed that the recovery of clean graphite was enhanced by 5.11% (NaCl) and 3.31% (MgCl 2 ) at 10 -2 mol/L, respectively, while gradually decreased by the addition of AlCl 3 . Moreover, the discussion on increasing the graphite recovery by 1% showed that 1.9 mmol/L Na + was equivalent to 3.0 mmol/L Mg 2+ , 18.3 J energy input, 7 mg/L 2-octyl alcohol and 0.9 mg/L diesel, respectively. It indicated that the addition of NaCl and MgCl 2 is of great significance for reducing carbon emission and cleaning flotation process. Our results can provide a valuable insight into the development of technology for surfactant adsorption and mineral flotation, especially for reducing carbon emission.