Innovative reactor designs
A multitude of flotation cell designs exist, build to address different challenges in flotation. In collaboration with process engineering companies, we prepare scaled-down cells for use in laboratory-experiments. Applying our advanced measurement methods we characterise properties of fluid flow, bubble dispersion and particle motion.
NextSTEP™
NextSTEP™ is a rotor-stator system by FLSmidth. This mechanical flotation unit is studied in-depth by the Flotsim project, connecting flow structures, bubble properties to flotation efficiency. [1]
Additionally, the flotation expertise of the NextSTEP™ unit is utilized in the CO2Valorize project for creating a carbon capture reactor. Particles containing calcium are mixed in the stirred tank and CO2 bubbles are injected. The reaction between particles and bubbles produces calcium carbonate. The aim is to capture CO2 in the off-gas of cement factories and feed the reaction product back into the cement production process as supplementary cementitious materials (SEMs).
REFLUX™ Flotation Cell (RFC)
The RFC by FLSmidth is a pneumatic flotation cell, focussing on fine particle flotation. Its slanted separator channels are designed to prevent bubbles from entering the underflow.
The project RFCUpscaling in close cooperation with the Helmholtz Institute Freiberg (HIF) studies the unique properties of this flotation cell. Investigations of the influence of wash water flux on the particle entrainment rate in the concentrate help in optimizing the work process of the cell. Additionally, the development of ultrasound measurement techniques allow for the detection of bubbles in the underflow while the cell is in operation and can inform the live adjustment of control parameter for better performance.
Imhoflot™ G-Cell
Maelgwyn Mineral Services Africa produces the Imhflot™ series of pneumatic flotation cells. The G-Cell specifically uses multiple horizontal jets to create an azimuthal flow, utilizing centrifugal forces for the separation of particle-laden bubbles from rejected tailings. Introduced in the FineFuture project, the model G-Cell experiment at the Helmholtz Institute Freiberg (HIF) is continued to be used in the RepNeu project for exploring the remining process of fine particles from old tailings, previously considered uneconomical.
Concorde Cell™
In a collaboration with the process engineering company Metso, we are investigating the properties of Metso’s Concorde Cell™. This pneumatic flotation cell distinguishes itself by the generation of bubbles by a plunging jet and a high degree of turbulence by accelerating a bubbly pipe flow up to supersonic speeds. The theoretical foundation of these physical systems are largely unexplored and require a thorough investigation, to connect flotation efficiency to the generated bubble size and potential shock waves within the cell.
Coarse particle flotation: Fluidized bed cell
The flotation of large particles is becoming a more and more relevant topic, as the grinding of particles is a very energy intensive process. A pre-selection of large particles that do or do not contain minerals of interest is such of high interest for an energy-efficient process. This can be achieved in a low-turbulence fluidized bed cell. The motion of air bubbles through tightly packed particles is tracked using X-ray imaging as their path has a high relevance for the unbiased pick-up of mineral-containing particles.
Publications
[1] H. Pervez, A. Hassan, A.-E. Sommer, T. Zürner, L. Pereira, M. Rudolph, S. Maaß, J. Bowden, and K. Eckert, A multi-sensor approach to measuring hydrodynamic parameters in a pyrite-quartz flotation system, Miner. Eng. 216, 108877 (2024), DOI: 10.1016/j.mineng.2024.108877.
