Iron Ore Beneficiation increases the grade of iron whilst maximising recovery and reduces the content of ultrafine low grade slimes to maximise return on investment from the mining process prior to sale or further refining in the iron making process. Existing technologies are deficient and hence the goal is to develop innovative approaches in dry beneficiation and wet gravity separation of fines.
The REFLUX™ Classifier offers significant potential in the wet beneficiation of fine iron ore covering a wide range of nominal particle sizes, from 6.3 mm down to 1.0 mm, 1.0 mm to 0.1 mm, and 0.1 mm to 0 mm. We have recently achieved remarkable separation performance over the range 0.1 mm to 0 mm by applying the REFLUX™ Classifier to a well liberated haematite ore, with grades in excess of 65 % and Fe recovery reaching 80 % across the full size range, with the recovery approximately 50 % below 0.020 mm and greater than 90 % above 0.038 mm. This work extends the recovery to sizes below those targeted by Amariei et al. (2013). Of specific interest here will be the influence of ore porosity, which lowers the particle density.
The Hub research will also be investigating the potential to enhance the performance of the REFLUX™ Classifier by incorporating the system within a high speed centrifuge, a new device known as the Graviton. Laboratory-scale semi-batch work on the Graviton has shown the capacity advantage of the inclined channels literally multiplies with the capacity advantages of the centrifugal force, permitting better than 1000-fold advantage with only 55 Gs (Galvin & Dickinson, 2013). Work is currently underway to perform pilot-scale continuous testing of this concept, utilizing 3-D printing technology to fabricate the inclined channel sections as modules that can be mounted into the centrifuge.
A novel idea for dry beneficiation, called the “Sink-Hole Fluidiser” is being investigated. This consists of a vibrating air-fluidized bed of sand particles coupled with a screening separation mechanism. Upon successful trials being obtained, a larger continuous version will be developed.
Initially the work focussed on separations at densities less than 2000 kg/m3 due to the availability of low density tracer particles. The work proved very successful showing sharp separations, and only modest shift in the cut point with particle size. The work conducted over the previous quarter shifted to higher separation densities. While waiting for the arrival of high density tracers, the research was developed around actual iron ore particles. Different media were introduced to shift the separation density to much higher levels. New experimental approaches were also developed, allowing the kinetics to be examined.
The aim of this project is to investigate whether the REFLUX™ Classifier technology can be adapted to enable it to perform dry density-based separations of ultrafine iron ore. There is a large economic competitive advantage in beneficiating iron ore in the dry state, as this avoids the costs of removing the moisture that is added during wet processing. However, dry beneficiation presents more technical challenges than wet systems, due to the greater difficulty in maintaining dynamic stability and the complexity of a dry solids handling system. Therefore, building a small scale test rig is essential to investigate these issues.
Dry Beneficiation Test Rig and Control system – Dry Beneficiation Rig
The primary purpose of this project is to use the REFLUX™ Classifier to process iron ore feeds in the -1.0 +0.045 mm size range to produce a high-quality free-draining iron ore product that is low in moisture content. Continuous steady-state experiments were performed on a spirals feed sample. Representative full-stream samples were collected from the feed, product and reject streams. A premium high-grade, high recovery iron ore product has been generated with almost no slime content from the received feed (i.e. low silicates and other contaminates). The work has also been able to achieve high shear induced lift that is needed to reject coarser gangue material and retain finer high density material across a particle size range from 0.125 to 1.0 mm.
REFLUX™ Classifier Test Rig
The objective of this project is to perform pilot-scale studies to develop a continuous steady state separator consisting of REFLUX™ Classifiers mounted inside a centrifuge, known as the Graviton. This project will deliver the next critical step needed to develop the Graviton concept into a full-scale commercial separator. A number of test runs have been successfully conducted with design improvements being identified as different operating conditions are evaluated for high volume flows at low pulp density versus lower volume flows at high pulp densities.