2924
Application of Hydrodynamic Cavitation Induced from the
Mach Reactor to Enhance the Flotation of Fine to Ultra‑Fine
PGMs from the Great Dyke Orebody
Adrian Singh
GoldOre (Pty) Ltd
Musawenkosi Dlame, Mehdi Safari
Mintek
ABSTRACT: PGM recoveries at a concentrator plant treating ore from the Selous Metallurgical Complex
(SMC), part of the Great Dyke orebody in Zimbabwe, have been decreasing over the years, a trend which has
been largely driven by operating at lower mass pulls in response to increasing mill capacity but constrained
smelting capacity. Mineralogical investigations have shown that the decline was mainly due to inefficient
flotation of fully liberated –20 micron PGMs, accounting for at least 50% of the losses.
Based on considerable success achieved in earlier work on improving the flotation performance of PGMs by
the application of the GoldOre Mach Reactor hydrodynamic cavitation Reactor on feed streams, a test pro-
gramme was conducted at the SMC plant laboratories on a mobile test rig to establish the likely impact of this
technology on the metallurgical performance of the plant. The Mach Reactor is a hydrodynamic cavitation
device (HCD) which generates nano-bubbles (NBs), typically a few hundred nanometres in size, when the
slurry passes through a series of venturi’s. Samples from the Rougher feed, Rougher Scavenger feed, Cleaner
feed and Final Tail streams of the SMC plant were subjected to tests in which the effect of preconditioning with
the Mach Reactor was assessed by subsequent bench flotation of the conditioned slurry. To better interpret the
bench kinetics with respect to the plant, a scale-down factor of 1/2.5 was applied throughout to set the labora-
tory retention times at which the analyses for the effect of the Mach Reactor were considered.
Preconditioning of the Rougher feed sample with the Mach Reactor for 5 passes yielded an average 4E recovery
improvement of 8.8%, these results being obtained after 6 minutes of rougher flotation (i.e., corresponding to
the 15 minutes in the plant). Increased kinetics and grade were achieved after 5 and 10 passes of precondition-
ing, being most noticeable during the early stages of flotation. It should be noted however that the calculated
head grades of the respective Rougher feed samples varied considerably, this being a result largely of the fluc-
tuations that are typically experienced when sampling streams on a concentrator at different times. For the
Rougher Scavenger feed stream, the kinetic results were grouped much more tightly than those of the Rougher
feed. Compared to the baseline after 10 minutes, a 5-pass preconditioning with the Mach returned a slight
recovery increase of 1.3%, increasing to 2.6% after 15 passes, but at the expense of a higher mass pull. Again,
the increased kinetics after preconditioning all but disappeared towards the latter stages of flotation.
Application of Hydrodynamic Cavitation Induced from the
Mach Reactor to Enhance the Flotation of Fine to Ultra‑Fine
PGMs from the Great Dyke Orebody
Adrian Singh
GoldOre (Pty) Ltd
Musawenkosi Dlame, Mehdi Safari
Mintek
ABSTRACT: PGM recoveries at a concentrator plant treating ore from the Selous Metallurgical Complex
(SMC), part of the Great Dyke orebody in Zimbabwe, have been decreasing over the years, a trend which has
been largely driven by operating at lower mass pulls in response to increasing mill capacity but constrained
smelting capacity. Mineralogical investigations have shown that the decline was mainly due to inefficient
flotation of fully liberated –20 micron PGMs, accounting for at least 50% of the losses.
Based on considerable success achieved in earlier work on improving the flotation performance of PGMs by
the application of the GoldOre Mach Reactor hydrodynamic cavitation Reactor on feed streams, a test pro-
gramme was conducted at the SMC plant laboratories on a mobile test rig to establish the likely impact of this
technology on the metallurgical performance of the plant. The Mach Reactor is a hydrodynamic cavitation
device (HCD) which generates nano-bubbles (NBs), typically a few hundred nanometres in size, when the
slurry passes through a series of venturi’s. Samples from the Rougher feed, Rougher Scavenger feed, Cleaner
feed and Final Tail streams of the SMC plant were subjected to tests in which the effect of preconditioning with
the Mach Reactor was assessed by subsequent bench flotation of the conditioned slurry. To better interpret the
bench kinetics with respect to the plant, a scale-down factor of 1/2.5 was applied throughout to set the labora-
tory retention times at which the analyses for the effect of the Mach Reactor were considered.
Preconditioning of the Rougher feed sample with the Mach Reactor for 5 passes yielded an average 4E recovery
improvement of 8.8%, these results being obtained after 6 minutes of rougher flotation (i.e., corresponding to
the 15 minutes in the plant). Increased kinetics and grade were achieved after 5 and 10 passes of precondition-
ing, being most noticeable during the early stages of flotation. It should be noted however that the calculated
head grades of the respective Rougher feed samples varied considerably, this being a result largely of the fluc-
tuations that are typically experienced when sampling streams on a concentrator at different times. For the
Rougher Scavenger feed stream, the kinetic results were grouped much more tightly than those of the Rougher
feed. Compared to the baseline after 10 minutes, a 5-pass preconditioning with the Mach returned a slight
recovery increase of 1.3%, increasing to 2.6% after 15 passes, but at the expense of a higher mass pull. Again,
the increased kinetics after preconditioning all but disappeared towards the latter stages of flotation.