Physics of Novel System Hydrodynamics

NO TITLE LEADER & KEY PERSONNEL PROJECT SUMMARIES

P1.2 Coarse Particle Separations

9 Enhancement of bubble-particle attachment and recovery at coarse particle size and low surface liberation

Leader: Prof Bill Skinner (UniSA)

Key Personnel: Prof Anh V Nguyen (UQ)

A/Prof Max Zanin, AI (UniSA)

PhD Student: James Dankwah (UniSA)

The project examines the complex interplay between hydrodynamics and pulp/surface chemistry in low-turbulence, froth-free fluidised bed flotation environments. Particle size distributions, composite particles (degree of surface liberation, simple-complex locking), operating parameters and feed preparation (wet, dry, chemistry), together with reagent type and strategy (collector, depressants, frother) are investigated in the context of specific application within flowsheets. Throughout 2022 a synthesis methodology has been developed to include fine magnetite into hydrophilic matrix, allowing enhanced contrast in CT/SEM (Computer Tomography/Scanning Electron Microscopy) and magnetic removal from process streams for analysis, such as concentrate-tailings comparison of surface liberation

13 Application of inclined channels in enhancing early gangue rejection through gravity and flotation separation - Applied

Leader: Prof Vishnu Pareek (Curtin)

Key Personnel:

L/Prof Kevin Galvin (UON)

Amira Global

The research looks to better understand the separation efficiency of a Reflux Classifier (RC). An RC Fractionator, currently being manufactured at the UON, will be acquired by Curtin. The RC Fractionator will be used to obtain the density distribution of the feed material (similar to sink-float washability data) using ore from a partner associated with the project through Amira Global.

10ii Enhancement of bubble-particle attachment and recovery at coarse particle size and low surface liberation - Part 2

Leader: Prof Anh V Nguyen (UQ)

Key Personnel: Prof Bill Skinner (UniSA)

PhD Student: Nhat Nguyen (UQ)

12 Determination of the Umf in fluidised bed flotation Leader:

L/Prof Graeme Jameson (UON)

PhD Student: Noyan Palabiyik (UOM)

A crucial factor in the effectiveness of coarse particle flotation systems is the attachment of bubbles to surfaces with low surface energy. In this project, the detachment with the bubble necking has been investigated. Special experimental designs and setups are under development to systematically investigate the detachment with composite surfaces, focusing on linking the characteristics of the bubble capillary necks, the slip-stick physics of the three-phase contact line, and the modelling of the attachment and detachment processes for coarse composite particles. The outcomes of these fundamental studies will be incorporated into pilot-scale studies using the HydroFloatTM cell.

This project looks to understand the behaviour of a polysized mixture of particles in a fluidised bed. If a bed of particles with a broad range of particle sizes is placed in a vertical column, and a constant flow of water is introduced at the base of the column, the finest particles will be carried out of the bed, leaving coarse particles behind.

Particles leaving the bed are elutriated. It is often assumed that the terminal velocity of elutriated particles under gravity is less than the upward flow velocity of the liquid.

Experiments have shown that some fine particles that should have been elutriated from the bed remain behind, while some coarse particles that should have remained, are carried out of the bed. A model has been developed to explain the experimental observations.

14 Application of inclined channels in enhancing early gangue rejection through gravity and flotation separation - Fundamental

Leader: L/Prof Kevin Galvin (UON)

Key Personnel: Prof Vishnu Pareek (Curtin)

Dr Angus Morrison (UQ)

Dr Kathryn Hadler, AI & Prof Jan Cilliers, AI (Imperial College)

PhD Students: Joshua Starrett (UON)

Luke Crompton (UON)

FLSmidth

If ores can be floated at coarser sizes, it is possible to significantly reduce energy consumption in comminution and downstream water consumption. The work has used a Reflux Classifier (RC) to achieve efficient size classification at high throughput and built new knowledge on how to control the separation size. This classification is important prior to applying coarse particle flotation. The coarse particles were floated using a novel CoarseAIR™ system to reject gangue minerals to the underflow. A new algorithm has been developed to measure the separation performance, using the rate constant as a proxy for surface liberation.

15 Influence of turbulence on coarse particle detachment from air bubbles

Leader: A/Prof Elham Doroodchi (UON)

Key Personnel: Prof Geoffrey Evans (UON)

A/Prof Kym Runge (UQ)

PhD Student: Syam Murali Mohan (UON)

A combined theoretical and experimental approach is being used to advance understanding of the interaction between fluid flow and particle-laden bubbles. Specifically, the rising behaviour of particle-laden bubbles in the presence of welldefined turbulent eddies is being investigated. The modified drag coefficient will ultimately improve the predictability of CFD models for multiphase systems such as flotation cells. A CFD framework for simulating turbulence distribution and predicting the degree of suspension in a conventional flotation cell has been established. Simulations and validation experiments for two-phase flows are currently in progress with the goal of developing a multiphase CFD model which can capture the role of the detachment mechanism on coarse particle flotation in a conventional cell.