2870
Reducing Fine Gangue Entrainment in Chalcopyrite Flotation in
Reflux Flotation Cell
Jiarui Chen, Yongjun Peng
School of Chemical Engineering, The University of Queensland
ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, The University of Queensland Node
ABSTRACT: With the depletion of mineral head grades and the increasing complexity of ore mineralogy,
the flotation circuits have to process finer particles with higher gangue entrainment. The Reflux Flotation Cell
(RFC) developed recently incorporates a reverse fluidized bed which eliminates the froth layer and allows the
application of strong wash water flow. These unique properties of the RFC’s reverse fluidized bed were explored
in this study to reduce fine gangue entrainment in chalcopyrite flotation. Flotation tests identified higher gangue
entrainment from chalcopyrite flotation, compared to coal flotation, under the baseline operating condition
optimized for coal flotation. This was attributed to the increased air fraction in chalcopyrite flotation as a
result of the higher density of hydrophobic particles, which transported a higher amount of entrained liquid
and gangue particles to the concentrate. Further flotation tests indicated that the increasing of wash water flux
reduced the entrainment in chalcopyrite flotation as expected, but the increasing of gas flux also reduced the
entrainment. Through CFD simulation, the latter was attributed to the formation of a liquid recirculation
loop in the RFC promoted by the increased gas flux, which assisted the mixing of wash water with the liquid
containing entrained particles, in favor of entrainment reduction. Therefore, the best gangue entrainment
reduction was achieved with the gas flux increased by 20% and the wash water flux increased by 30% from
the baseline condition, where the benefits of increasing gas flux and wash water flux in entrainment reduction
could both be fully realized. This study identified the best operating condition for minimizing fine gangue
entrainment in base metal sulphide flotation in the RFC together with the most favorable fluid flow created.
INTRODUCTION
The Reflux Flotation Cell (RFC) developed in recent years
demonstrates great potential in resolving the urgent chal-
lenges in the resources industry by expanding the process-
able particle size and increasing the process throughput.
The RFC may also reduce fine gangue entrainment during
flotation. As shown in Figure 1, the RFC consists of three
major components, a downcomer, an inclined channels
panel and a reverse fluidized bed. During the operation, the
feed slurry is mixed with compressed air within the down-
comer and discharged as a bubble-slurry mixture into the
inclined channels where the bubbles and attached particles
quickly separate from the tail stream (Cole et al., 2021).
Then, the bubble-particle aggregates raise into the reverse
fluidized bed for further separation from unattached par-
ticles. In this region, a strong downward wash water flow
is added from the top, fluidizes the uprising bubble stream
and prevents the formation of packed froth layers (Jiang
et al., 2019). In traditional flotation, the narrow channels
between the bubbles in froth layers have been regarded as a
limiting factor for entrainment reduction by slowing down
the drainage of entrained liquid and particles (Cutting et
Reducing Fine Gangue Entrainment in Chalcopyrite Flotation in
Reflux Flotation Cell
Jiarui Chen, Yongjun Peng
School of Chemical Engineering, The University of Queensland
ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals, The University of Queensland Node
ABSTRACT: With the depletion of mineral head grades and the increasing complexity of ore mineralogy,
the flotation circuits have to process finer particles with higher gangue entrainment. The Reflux Flotation Cell
(RFC) developed recently incorporates a reverse fluidized bed which eliminates the froth layer and allows the
application of strong wash water flow. These unique properties of the RFC’s reverse fluidized bed were explored
in this study to reduce fine gangue entrainment in chalcopyrite flotation. Flotation tests identified higher gangue
entrainment from chalcopyrite flotation, compared to coal flotation, under the baseline operating condition
optimized for coal flotation. This was attributed to the increased air fraction in chalcopyrite flotation as a
result of the higher density of hydrophobic particles, which transported a higher amount of entrained liquid
and gangue particles to the concentrate. Further flotation tests indicated that the increasing of wash water flux
reduced the entrainment in chalcopyrite flotation as expected, but the increasing of gas flux also reduced the
entrainment. Through CFD simulation, the latter was attributed to the formation of a liquid recirculation
loop in the RFC promoted by the increased gas flux, which assisted the mixing of wash water with the liquid
containing entrained particles, in favor of entrainment reduction. Therefore, the best gangue entrainment
reduction was achieved with the gas flux increased by 20% and the wash water flux increased by 30% from
the baseline condition, where the benefits of increasing gas flux and wash water flux in entrainment reduction
could both be fully realized. This study identified the best operating condition for minimizing fine gangue
entrainment in base metal sulphide flotation in the RFC together with the most favorable fluid flow created.
INTRODUCTION
The Reflux Flotation Cell (RFC) developed in recent years
demonstrates great potential in resolving the urgent chal-
lenges in the resources industry by expanding the process-
able particle size and increasing the process throughput.
The RFC may also reduce fine gangue entrainment during
flotation. As shown in Figure 1, the RFC consists of three
major components, a downcomer, an inclined channels
panel and a reverse fluidized bed. During the operation, the
feed slurry is mixed with compressed air within the down-
comer and discharged as a bubble-slurry mixture into the
inclined channels where the bubbles and attached particles
quickly separate from the tail stream (Cole et al., 2021).
Then, the bubble-particle aggregates raise into the reverse
fluidized bed for further separation from unattached par-
ticles. In this region, a strong downward wash water flow
is added from the top, fluidizes the uprising bubble stream
and prevents the formation of packed froth layers (Jiang
et al., 2019). In traditional flotation, the narrow channels
between the bubbles in froth layers have been regarded as a
limiting factor for entrainment reduction by slowing down
the drainage of entrained liquid and particles (Cutting et