2064 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
magnetite and silica in a spiral concentrator demonstrates
the particle segregation behavior based on their specific
gravity, as it offers significant advantages in terms of con-
trol, easy of component separation from the mixture, clear
understanding, and exploration of the separation process.
Experimental data obtained from tests with the synthetic
slurry can be used to validate and develop a computational
model of the spiral concentrator. In order to facilitate the
heavy mineral grade analysis, magnetite was chosen as the
heavy mineral in the synthetic ore. Magnetite (SG=5.0) has
a similar specific gravity to hematite (SG=5.26), and can
be easily separated from the silica (SG=2.65) by a magnetic
separator. For a better understanding of the particle size-
wise segregation along the trough surface, the final turn of
the high-gravity spiral is divided into five zones. Figure 2
shows the partition of cross-sectional spiral trough into dif-
ferent separation zones and the location of slurry collec-
tions in a spiral concentrator.
Eexperiments are performed at 10 wt% feed solids
content with different proportions of magnetite and Silica
(0:100, 20:80, 50:50, 100:0) at 4 m3/h. The feed of the
spiral was prepared in the mixing tank located below the
spiral. The details of the amount of synthetic ore taken to
form the slurry at 10 wt% is given in Table 2. Agitation
of the slurry is to be performed continuously to prevent
solid blockage and to minimize the preferential settling
of the heavy minerals. Once a steady state is achieved, the
concentrate, middlings, and tailings slurries are simultane-
ously collected three times in each experiment to determine
the mass flow rate. After measuring the mass flow rates,
two sets of samples are taken from the separation zones at
the 5th turn of the spiral trough. One sample is utilized
to measure the solids percentage, while the other set goes
to the separation of magnetite and silica using a magnetic
separator. Throughout all experiments, efforts were made
to ensure that magnetite recovery exceeded 95%. The par-
ticle size distribution of the recovered magnetite and silica
is then measured using a Microtrac s3500 particle laser size
analyzer.
RESULTS AND DISCUSSION
From Figure 3, the particle size distribution (PSD) of mag-
netite and silica in the feed reveals that 80% of magnetite
particles are below 44 µm, while 80% of silica particles are
below 34.92 µm. Similarly, 50% of magnetite particles are
less than 27 µm, and 50% of silica particles are less than
15.29 µm.
The artificial feed mixture, composed of particles with
different densities, undergoes the effects of both centrifugal
and gravitational forces during processing. Partitioning the
final turn of the spiral trough into separation zones allows
for a more detailed analysis of the particle distribution of
magnetite and silica. However, specific particle sizes in each
zone will depend on the particular characteristics of the
Figure 2. Sectional partitioning of spiral trough (5th turn)
Table 2. Amount of magnetite to silica ratio taken in the feed (Kgs) at 10% solids
S.No
Feed proportion
(Magnetite :Silica) Magnetite (kg) Silica (kg) Water (kg)
1 0:100 0 14 126
2 20:80 2.8 11.2 126
3 50:50 7 7 126
4 100:0 14 0 126
magnetite and silica in a spiral concentrator demonstrates
the particle segregation behavior based on their specific
gravity, as it offers significant advantages in terms of con-
trol, easy of component separation from the mixture, clear
understanding, and exploration of the separation process.
Experimental data obtained from tests with the synthetic
slurry can be used to validate and develop a computational
model of the spiral concentrator. In order to facilitate the
heavy mineral grade analysis, magnetite was chosen as the
heavy mineral in the synthetic ore. Magnetite (SG=5.0) has
a similar specific gravity to hematite (SG=5.26), and can
be easily separated from the silica (SG=2.65) by a magnetic
separator. For a better understanding of the particle size-
wise segregation along the trough surface, the final turn of
the high-gravity spiral is divided into five zones. Figure 2
shows the partition of cross-sectional spiral trough into dif-
ferent separation zones and the location of slurry collec-
tions in a spiral concentrator.
Eexperiments are performed at 10 wt% feed solids
content with different proportions of magnetite and Silica
(0:100, 20:80, 50:50, 100:0) at 4 m3/h. The feed of the
spiral was prepared in the mixing tank located below the
spiral. The details of the amount of synthetic ore taken to
form the slurry at 10 wt% is given in Table 2. Agitation
of the slurry is to be performed continuously to prevent
solid blockage and to minimize the preferential settling
of the heavy minerals. Once a steady state is achieved, the
concentrate, middlings, and tailings slurries are simultane-
ously collected three times in each experiment to determine
the mass flow rate. After measuring the mass flow rates,
two sets of samples are taken from the separation zones at
the 5th turn of the spiral trough. One sample is utilized
to measure the solids percentage, while the other set goes
to the separation of magnetite and silica using a magnetic
separator. Throughout all experiments, efforts were made
to ensure that magnetite recovery exceeded 95%. The par-
ticle size distribution of the recovered magnetite and silica
is then measured using a Microtrac s3500 particle laser size
analyzer.
RESULTS AND DISCUSSION
From Figure 3, the particle size distribution (PSD) of mag-
netite and silica in the feed reveals that 80% of magnetite
particles are below 44 µm, while 80% of silica particles are
below 34.92 µm. Similarly, 50% of magnetite particles are
less than 27 µm, and 50% of silica particles are less than
15.29 µm.
The artificial feed mixture, composed of particles with
different densities, undergoes the effects of both centrifugal
and gravitational forces during processing. Partitioning the
final turn of the spiral trough into separation zones allows
for a more detailed analysis of the particle distribution of
magnetite and silica. However, specific particle sizes in each
zone will depend on the particular characteristics of the
Figure 2. Sectional partitioning of spiral trough (5th turn)
Table 2. Amount of magnetite to silica ratio taken in the feed (Kgs) at 10% solids
S.No
Feed proportion
(Magnetite :Silica) Magnetite (kg) Silica (kg) Water (kg)
1 0:100 0 14 126
2 20:80 2.8 11.2 126
3 50:50 7 7 126
4 100:0 14 0 126