Utilization of entrainment for a gravity based recovery of ultrafine particles

Abstract

Ultrafine particle recovery poses a complicated challenge to be solved, due to the low collision efficiency with bubbles in flotation processes and a high recovery of gangue material by entrainment. As a result, losses of valuable metals occur. In the present work, a novel approach was chosen for the recovery of ultrafine particles. Instead of flotation, entrainment was used for a gravity based particle recovery. A 3D-printed particle collector was designed to recover the particles at the top of a bubble column. To obtain a good understanding about the density dependence of the process, SiO₂, Ni and W particles were used to cover a density range of 2.65-19.28 g$\cdot$cm^-3. High recoveries were achieved for Ni (73 %) and W (59 %) particles. SiO₂ was only recovered in high amounts ($\approx$50 %) when particle sizes exceeded $10\mu m$. An extensive investigation of the flow regime was performed to gain an overview about the correlation in between flow regime and particle recovery results.