Investigating the selective separation of very fine magnetite and quartz particles using two-liquid flotation

One of the research key aspects of the Helmholtz-Institute Freiberg (HIF), founded in 2011, lies in the further development of efficient beneficiation concepts for disseminated mineral resources, and thus, in processing (ultra)fine particles effectively. In this paper we present results of a fundamental study regarding the selective separation of very fine particles by two-liquid flotation, a flotation-related process using oil droplets instead of air bubbles. Experimental tests use iso-octane and water as the two immiscible liquid phases and fine, below 10 micron respectively, magnetite and quartz particles as the chosen academic solid mixture. The selective accumulation of the solids at the oil/water interface or the transfer into the oil phase, respectively, was investigated depending on several process parameters including pH and surfactant concentration. Furthermore, the selective transfer of magnetite particles from the aqueous with a high yield into the oil phase is demonstrated by means of a modified laboratory-scale flotation column.