Physics of Novel System Hydrodynamics

NO TITLE LEADER & KEY PERSONNEL PROJECT SUMMARIES

P1.3 Fine Particle Separation (continued)

23 Mechanism for coarsening of flotation froths Leader:

Prof Anh Nguyen (UQ)

Key Personnel:

Prof Roe-Hoan Yoon, AI (VT)

Dr Liguang Wang, AI (UQ)

Prof Stephen Neethling, AI (Imperial College)

PhD Student: Thao Nguyen (UQ)

The mechanisms of froth coarsening in the presence of frothers are only partially understood. Modelling and experimental work on the effect of salts on the interfacial adsorption and the foamability of methyl isobutyl carbinol (MIBC) solutions has been performed to investigate both the macroscopic and microscopic elements of froth drainage and froth stability. At the macroscopic level, the froth drainage has been investigated using a Microcell and a Jameson Cell. A theoretical framework and experimental setup is currently being implemented to investigate complex interactions between frother dosage, gas/liquid flow rates, and hydrophobic particles. At the microscopic level, the effect of surfactant charge on the interfacial water structure and its relative macroscopic properties such as foamability and foam stability is currently being investigated.

25 Carbon removal from gold ores using novel agglomeration Leader:

L/Prof Kevin Galvin (UON)

Key Personnel:

Prof Vishnu Pareek (Curtin)

Prof Anh Nguyen (UQ)

Jord International Amira Global

Preg-robbing of gold from leach solutions by certain minerals is a significant problem in some gold processing facilities. Initial test work has evaluated the performance of the 3D binder developed by UON in removing preg-robbing carbon through agglomeration. A synthetic ore system consisting of pulverised activated carbon, silica and pyrite has been used to represent the typical preg-robbing materials found in the gold industry. First, the agglomeration methodology was compared to tests using pure activated carbon, and the dosage was optimised for the carbon system. Second, the agglomeration was tested in a more complex system using silica and pyrite in addition to the preg-robbing carbon phase. The tests indicated high removal of the pre-robbing material, but low selectivity for silica and pyrite. Future tests will look to optimise the dosage of the binder and improve the separability between the preg-robbing material and the silica and pyrite.

24 Hydrodynamics of an emerging froth from a concentrated bubble column Leader: Prof Geoffrey Evans (UON)

Key Personnel:

Dr Subhasish Mitra (UON)

Dr Peter Ireland (UON)

Prof Jan Cilliers, AI (Imperial College)

PhD Student: Abdullaziz Zakari (UON)

The project is concerned with gaining a fundamental understanding of the hydrodynamics in the REFLUX™ Flotation Cell. Studies included determining the collision efficiency in a multi-bubble-particle system, critical turbulence energy dissipation rate for particle detachment from a bubble-particle aggregate, and the effect of solid loading on bubble rise velocity in the presence of surfactant. Also, a multiphase CFD model for a rectangular bubble column was developed to study the bubble plume dispersion behaviour in the top fluidised bed section of an RFC system. The aim is to quantify flow field, gas volume fraction, and the turbulence energy dissipation rate at different gas superficial velocities. Some preliminary studies have also been conducted to examine the transition from the bubbly zone to the froth zone in this system and quantify froth growth kinetics.

26 Ultrafine recovery of precious metals using nano-scale permeable films of oil

Leader: L/Prof Kevin Galvin (UON)

Key Personnel:

Prof Vishnu Pareek (Curtin)

Prof Robert H. Davis, PI (Uni Colorado Boulder)

PhD Student: Meolla Yvon (UON)

Jord International

The capture and separation of ultrafine hydrophobic particles is critical to several processes, including improving recovery in flotation and in the removal of competing adsorbents in gold processing. This project aims to develop and analyse a novel agglomeration technology that utilises a concentrated water-in-oil emulsion to act as a hydrophobic medium for capturing ultrafine hydrophobic particles.

The theoretical work led by Prof Davis has confirmed that a permeable interface leads to vastly higher capture rates. Experimental work is focusing on selectivity, and efficacy of the emulsion binder. Curtin has been developing the laboratory method for gold processing, while UON is collaborating with our industrial partner Jord to build a full-scale facility on a mine site.

27 Ultrafine gravity separation using inclined channels subjected to different G forces including standard gravity

Leader:

L/Prof Kevin Galvin (UON)

Key Personnel:

Dr Angus Morrison (UQ)

A/Prof Aaron Noble, PI (VT)

PhD Student: Margaret Amosah (UON)

FLSmidth

Process intensification in the processing of particles below 0.15 mm is critical to addressing current process limitations, which are known to produce mineral losses and larger volumes of tailings waste. The research explores the use of inclined channels in the gravity separation and desliming of these relatively fine particles, targeting the usual domain of flotation.

Following work on the processing of tailings to concentrate cassiterite and manganese dioxide, new work was conducted on ultrafine iron ore. Remarkable separations have been achieved with new knowledge developed concerning the partition surface obtained. The work has also highlighted the potential for solving a 30-year-old problem in recovering cassiterite from tailings. The work with the manganese ore is looking to achieve industry impact using closely spaced inclined channels. The next stage development, applying g-forces to the inclined channels, is now entering the commercialisation phase, with support from Centre partner FLSmidth.