XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2107
one (magnetite) was at the finer end and the curve for the
overall mixture was in between the curves for the low and
high-density components. The following observations were
made from the results obtained from the bi-component
hydrocyclone performance tests-
• The high-density component has a smaller cut size
compared to the light-density component. The cut
size values for the overall mixture are found to be in
between the light and heavy components.
• The sharpness of the separation, ‘α’, is higher for the
low-density component than that of the high-den-
sity component indicating that in this system there
is a higher misplacement of heavier finer particles to
underflow .
• The component proportion in the mixture appeared
to have a significant effect on the cut size (d50i) and
the sharpness of separation (α) for individual compo-
nent efficiency curves (See Figure 3(b)).
The components’ classification behaviour in the mixture
and pure (only magnetite or silica) slurry system of the
hydrocyclone experiment are found to be different (see
Figure 4).
The cut size for both the heavier and lighter density
components in a mixture is larger than the pure-compo-
nent slurry system. The change in cut size behaviour indi-
cates an interaction between components is taking place
in the hydrocyclone during the classification action of the
mixture. Considering the interaction between components,
the assumption of average mixture density in mathematical
models for predicting the individual component cut sizes
is not be valid, particularly where the component density
differences are significantly large. Padhi et al., 2019 [5]
introduced the “Interaction co-efficient” to explain the
interaction between components during the classification
performance to assess the component effect on separation
size. The parametric studies focussed on assessing classifica-
tion of different component mixtures in the hydrocyclone
indicated that increasing the magnetite percentage in the
feed comprising magnetite and silica resulted in increased
fluctuations of the silica content towards the forced vortex.
The possibility of light density particles being engulfed in
the stream of particles flowing towards the underflow due
to the wake formation is a notable phenomenon, which
leads to misplacement of particles due to density differences
during n the separation process [24]. The interactions of
the different density particles increases with increase in the
percentage of magnetite.
Insights from Multicomponent CFD Studies
The multicomponent CFD studies presented in (Padhi et.
al, 2019) [5] and (Padhi et. al, 2020) [4] show the hydrocy-
clone classification performance of magnetite and silica for
mixtures containing t different ratios of these components
for varying solids concentrations. It was observed that the
interaction of particles changes in the system changes indi-
cating that the percentage of magnetite present in the feed
slurry has an influence on the separation performance. The
change in interaction can be by observing the shift in the
Locus of Zero Vertical Velocity (LZVV). The LZVV is an
imaginary line inside the turbulent flow of hydrocyclone
where the vertical velocity becomes zero due to the exis-
tence of forced and free vortex flows (Rankine vortex). The
LZVV is one of the important concepts that can be used to
assess classification behaviour when variables that are not
to influence separation are altered. For this study, the vari-
ables of interest were the feed slurry property, which were
altered by changing the ratio of magnetite to silica and the
solids concentration of the slurry and operating conditions
that includes feed pressure. Figure 5(a) illustrates the CFD
validation for performances of particles 50:50 proportion
silica: magnetite in 3-inch hydrocyclone (10 wt. %feed
solids) and 5(b) represents the 3-inch hydrocyclone LZVV
shift for various proportion of magnetite.
Similarly, the mean position of volume fraction tracked
for different sizes also illustrates the shift in the position for
pure component classification and particles in the mixture
(Padhi et al., 2021) [27]. In mineral processing circuits, the
feed to hydrocyclone consists of different density particle
system at varying degrees of liberation and sizes, leading to
a multi-component system. These different density com-
ponents’ interaction affects the separation in the hydro-
cyclones, particularly at high feed solids concentrations.
Customized orthogonal array experiments were carried out
using three-spigot and pressure level for 3" and 4" hydro-
cyclones. Components’ grade efficiency curves and the
performance parameters (d50 Rf Rs α β) were estimated
and analysed using the Whiten Equation. The cut-size and
beta parameter of the mixture and individual components
witnessed to increase with increasing feed solids concentra-
tion. Suspension rheology and hindered settling rate stud-
ies were carried out to understand the influence of the fine
and coarse particle interaction on the performance of the
hydrocyclone processing bi-component mixture at differ-
ent feed solids concentrations. The enhanced viscous flow
at the conical region attributes the crowding effect and the
dense medium effect near apex zone, and consequential
one (magnetite) was at the finer end and the curve for the
overall mixture was in between the curves for the low and
high-density components. The following observations were
made from the results obtained from the bi-component
hydrocyclone performance tests-
• The high-density component has a smaller cut size
compared to the light-density component. The cut
size values for the overall mixture are found to be in
between the light and heavy components.
• The sharpness of the separation, ‘α’, is higher for the
low-density component than that of the high-den-
sity component indicating that in this system there
is a higher misplacement of heavier finer particles to
underflow .
• The component proportion in the mixture appeared
to have a significant effect on the cut size (d50i) and
the sharpness of separation (α) for individual compo-
nent efficiency curves (See Figure 3(b)).
The components’ classification behaviour in the mixture
and pure (only magnetite or silica) slurry system of the
hydrocyclone experiment are found to be different (see
Figure 4).
The cut size for both the heavier and lighter density
components in a mixture is larger than the pure-compo-
nent slurry system. The change in cut size behaviour indi-
cates an interaction between components is taking place
in the hydrocyclone during the classification action of the
mixture. Considering the interaction between components,
the assumption of average mixture density in mathematical
models for predicting the individual component cut sizes
is not be valid, particularly where the component density
differences are significantly large. Padhi et al., 2019 [5]
introduced the “Interaction co-efficient” to explain the
interaction between components during the classification
performance to assess the component effect on separation
size. The parametric studies focussed on assessing classifica-
tion of different component mixtures in the hydrocyclone
indicated that increasing the magnetite percentage in the
feed comprising magnetite and silica resulted in increased
fluctuations of the silica content towards the forced vortex.
The possibility of light density particles being engulfed in
the stream of particles flowing towards the underflow due
to the wake formation is a notable phenomenon, which
leads to misplacement of particles due to density differences
during n the separation process [24]. The interactions of
the different density particles increases with increase in the
percentage of magnetite.
Insights from Multicomponent CFD Studies
The multicomponent CFD studies presented in (Padhi et.
al, 2019) [5] and (Padhi et. al, 2020) [4] show the hydrocy-
clone classification performance of magnetite and silica for
mixtures containing t different ratios of these components
for varying solids concentrations. It was observed that the
interaction of particles changes in the system changes indi-
cating that the percentage of magnetite present in the feed
slurry has an influence on the separation performance. The
change in interaction can be by observing the shift in the
Locus of Zero Vertical Velocity (LZVV). The LZVV is an
imaginary line inside the turbulent flow of hydrocyclone
where the vertical velocity becomes zero due to the exis-
tence of forced and free vortex flows (Rankine vortex). The
LZVV is one of the important concepts that can be used to
assess classification behaviour when variables that are not
to influence separation are altered. For this study, the vari-
ables of interest were the feed slurry property, which were
altered by changing the ratio of magnetite to silica and the
solids concentration of the slurry and operating conditions
that includes feed pressure. Figure 5(a) illustrates the CFD
validation for performances of particles 50:50 proportion
silica: magnetite in 3-inch hydrocyclone (10 wt. %feed
solids) and 5(b) represents the 3-inch hydrocyclone LZVV
shift for various proportion of magnetite.
Similarly, the mean position of volume fraction tracked
for different sizes also illustrates the shift in the position for
pure component classification and particles in the mixture
(Padhi et al., 2021) [27]. In mineral processing circuits, the
feed to hydrocyclone consists of different density particle
system at varying degrees of liberation and sizes, leading to
a multi-component system. These different density com-
ponents’ interaction affects the separation in the hydro-
cyclones, particularly at high feed solids concentrations.
Customized orthogonal array experiments were carried out
using three-spigot and pressure level for 3" and 4" hydro-
cyclones. Components’ grade efficiency curves and the
performance parameters (d50 Rf Rs α β) were estimated
and analysed using the Whiten Equation. The cut-size and
beta parameter of the mixture and individual components
witnessed to increase with increasing feed solids concentra-
tion. Suspension rheology and hindered settling rate stud-
ies were carried out to understand the influence of the fine
and coarse particle interaction on the performance of the
hydrocyclone processing bi-component mixture at differ-
ent feed solids concentrations. The enhanced viscous flow
at the conical region attributes the crowding effect and the
dense medium effect near apex zone, and consequential