Influence of operating parameters on nanobubble-assisted flotation of graphite

Abstract

Although many studies have focused on processing of lithium-ion batteries (LiBs), there is a considerable lack of information concerning the application of nanobubbles (NBs) in their floatabilities. To cover this knowledge gap, the current study aims at exploring the effect of key operating parameters on flotation of two types of graphite i.e., lithium-ion batteries’ graphite (LIBG) and natural ore graphite (NOG) in the presence of NBs. For this purpose, the effects of NB solution ratio, impeller speed, air flow rate, as well as dosage and type of collector and frother on recovery of graphite were investigated in the presence and absence of NBs. Three frothers (i.e., methyl isobutyl carbinol (MIBC), terpenic oil, and 2-octanol), and three collectors (i.e., n-dodecane, kerosene and diesel oil) were employed for comparison purposes using an XFG micro-flotation unit. The hydrodynamic cavitation and dynamic light scattering (DLS) methods were utilized to produce and characterize ultrafine bubbles, respectively. The DLS results confirmed the bubble size distribution ranged between 180 and 400 nm. The maximum recovery of graphite particles (ca. 98%) was obtained for the LIBG particles, at an impeller speed of 1000 rpm, air flow rate of 0.4 L/min, using 2-octanol as a frother, and n-dodecane as a collector. Further, the influential order of the frothers was found as 2-octanol > terpenic oil > MIBC. According to the flotation results, the presence of NBs increased the LIBG flotation recovery and its kinetic rate by 15% and 33%, respectively.