XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2021
decrease the intensity of this phenomenon. When fluidiza-
tion pressure is high, the values of RRb and ERRb are limited.
For example, at 100 Gs and 2 PSI, RRb is 5% and ERRb is
0.8, whereas at 100 Gs and 8 PSI, RRb is 3.5% and ERRb
is 0.7.
DISCUSSION
Behaviour of Particles in the Retention Zone
The mass yield represents the ratio of the mass material
found in the bowl at the end of the experiment and the
sample mass. This mass never represents more than 7.4%
and less than 1.5% of the sample mass in the range of tested
values (Figure 4). As rotation speed increases the mass yield
increases and seems to reach a plateau after 150 G’s with
between 5 and 7% mass yield. The variation of mass yield
for a given rotation speed value is due to the intensity of
the fluidization water, the more intense the fluidization, the
lower the mass yield (Figure 4 A). Fluidization water pres-
sure has an opposite effect, as pressure increases the mass
yield decreases. For example, at 50 G’s, mass yield decreases
from 6.3% to 3.5% when fluidization pressure increases
from 1 to 7 PSI. Above 150 G’s, the effect of fluidization
pressure on the mass yield seems to be limited. Indeed,
mass yield decreases of only 1% when fluidization pressure
increases from 1 to 10 PSI.
Results show the clear opposition between the effects of
the two tested parameters. Rotation speed tends to increase
the centrifugal force undergone by the particles, which
forces the particle bed in the retention zone to pack more
and to trap smaller particles that would be ejected if the
rotation was weaker. Fluidization water tends to increase
the ejection force undergone by the particles in the reten-
tion zone, which forces the particle bed to unpack and allow
the ejection of lighter and smaller particles that would stay
if the fluidization water was weaker. The opposite role of
those two parameter on the behaviour of particles in this
kind of fluidized bowl is the working principle of these con-
centrators and as already been described by other authors
(Foucaud et al., 2019). In the case of the –280µm Beauvoir
ore, it seems that there is no benefit in increasing the rota-
tion speed further than 100–150 G’s since at this rotation
speed – and whatever the applied fluidization pressure -
since the retention zone in the bowl is saturated and the
effect of fluidization water is no more noticeable.
Mass Yield and Metallurgical Performances
Given that the samples utilized in this study are all iden-
tical, the mass yield is solely influenced by the applied
machine parameters. Therefore, it is intriguing to explore
the relationship between the mass yield and the metallurgi-
cal performance of the separation. The evolution of Sn, Nb,
and Ta enrichment ratios and recoveries follows a similar
trend in relation to mass yield (Figure 5). Enrichment ratios
exhibit an almost linear decrease as the mass yield increases,
while recoveries demonstrate a parabolic behavior, increas-
ing, reaching a maximum around a mass yield of 6%, and
decreasing thereafter (Figure 5).
The linear trend in the enrichment ratio and the para-
bolic trend in recovery are evident for Sn, less pronounced
Figure 4. Evolution of mass yield in function of machine parameters settings. Left: Mass yield versus rotation speed. Right:
Mass yield versus fluidization pressure (PSI)
decrease the intensity of this phenomenon. When fluidiza-
tion pressure is high, the values of RRb and ERRb are limited.
For example, at 100 Gs and 2 PSI, RRb is 5% and ERRb is
0.8, whereas at 100 Gs and 8 PSI, RRb is 3.5% and ERRb
is 0.7.
DISCUSSION
Behaviour of Particles in the Retention Zone
The mass yield represents the ratio of the mass material
found in the bowl at the end of the experiment and the
sample mass. This mass never represents more than 7.4%
and less than 1.5% of the sample mass in the range of tested
values (Figure 4). As rotation speed increases the mass yield
increases and seems to reach a plateau after 150 G’s with
between 5 and 7% mass yield. The variation of mass yield
for a given rotation speed value is due to the intensity of
the fluidization water, the more intense the fluidization, the
lower the mass yield (Figure 4 A). Fluidization water pres-
sure has an opposite effect, as pressure increases the mass
yield decreases. For example, at 50 G’s, mass yield decreases
from 6.3% to 3.5% when fluidization pressure increases
from 1 to 7 PSI. Above 150 G’s, the effect of fluidization
pressure on the mass yield seems to be limited. Indeed,
mass yield decreases of only 1% when fluidization pressure
increases from 1 to 10 PSI.
Results show the clear opposition between the effects of
the two tested parameters. Rotation speed tends to increase
the centrifugal force undergone by the particles, which
forces the particle bed in the retention zone to pack more
and to trap smaller particles that would be ejected if the
rotation was weaker. Fluidization water tends to increase
the ejection force undergone by the particles in the reten-
tion zone, which forces the particle bed to unpack and allow
the ejection of lighter and smaller particles that would stay
if the fluidization water was weaker. The opposite role of
those two parameter on the behaviour of particles in this
kind of fluidized bowl is the working principle of these con-
centrators and as already been described by other authors
(Foucaud et al., 2019). In the case of the –280µm Beauvoir
ore, it seems that there is no benefit in increasing the rota-
tion speed further than 100–150 G’s since at this rotation
speed – and whatever the applied fluidization pressure -
since the retention zone in the bowl is saturated and the
effect of fluidization water is no more noticeable.
Mass Yield and Metallurgical Performances
Given that the samples utilized in this study are all iden-
tical, the mass yield is solely influenced by the applied
machine parameters. Therefore, it is intriguing to explore
the relationship between the mass yield and the metallurgi-
cal performance of the separation. The evolution of Sn, Nb,
and Ta enrichment ratios and recoveries follows a similar
trend in relation to mass yield (Figure 5). Enrichment ratios
exhibit an almost linear decrease as the mass yield increases,
while recoveries demonstrate a parabolic behavior, increas-
ing, reaching a maximum around a mass yield of 6%, and
decreasing thereafter (Figure 5).
The linear trend in the enrichment ratio and the para-
bolic trend in recovery are evident for Sn, less pronounced
Figure 4. Evolution of mass yield in function of machine parameters settings. Left: Mass yield versus rotation speed. Right:
Mass yield versus fluidization pressure (PSI)