Advances in the potential application of froth flotation for the recovery of graphite from spent alkaline and Zn/C batteries

Abstract

The recovery of graphite has been investigated mainly for black mass from spent Li-ion batteries. However, less research has been performed on the graphite recovery from spent Zn/C and alkaline batteries. Graphite is a critical raw material and it is necessary to search for new secondary sources to recover it. The main advance of this research is to study the application of froth flotation for the recovery of graphite from black mass of spent Zn/C and alkaline batteries. The effect of two thermal pre-treatment processes (roasting at 340ºC and pyrolysis at 600ºC) plus an attrition stage previous froth flotation have been analyzed. Experimental results showed that pyrolysis treatment of black mass from Zn/C and alkaline batteries allows greater selectivity of graphite versus Mn/Zn minerals. This may be due to a modification of the particle size do related to the removal of the finest ones, as well as a modification of the surface chemistry of the graphite and/or manganese oxides. In addition, the thermal treatment also modifies the mineralogical composition of the Mn oxides.