2068 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
This inverse relationship between the percentage of silica
and the average size of magnetite highlights the impact of
feed composition on the particle size distribution. As the
silica percentage increases in the mixture, the average size
of silica predominantly increases in outer zones, while this
trend is not prominent in inner zones. This reinforces the
idea of hindered settling or liberation from magnetite clus-
ters in the denser mixture. Similarly, with an increase in
the silica percentage, the average size of magnetic particles
significantly decreases in outer zones but is less effective in
inner zones. This is likely due to the dominant influence of
centrifugal force, pushing fine magnetite outwards. Higher
silica content leads to smaller average magnetite size across
most zones, suggesting association and hindered settling as
key factors impacting separation efficiency. Silica size also
shows some variation with changes in feed composition,
potentially due to competition for space, hindered settling,
or liberation from magnetite clusters.
CONCLUSIONS
The overall objective of this study is to explore the compo-
nent interactions along the spiral trough and the effect of
particle separation w.r.t to feed proportion in spiral con-
centrators. The main conclusions can be drawn as follows:
In pure feed streams, magnetite particle size progres-
sively decreases from inner to outer zones (concentration
to tailings) due to centrifugal force, while silica exhibits a
more complex trend with accumulation in zone 1 and then
decrease in size.
Low centrifugal force leads to minimal change in aver-
age size for silica and accumulation of finer silica with
coarser magnetite, resulting in marginal separation and nar-
rower size distribution curves.
Strong gravitational and centrifugal forces effectively
concentrate finer magnetite towards the center and decrease
average sizes for both minerals in intermediate zones (zones
2 &3), exhibiting wider size distribution curves and signi-
fying significant separation zones.
Strongest centrifugal force directs finest magnetite to
tailings and reduces silica size significantly in outer zones
(zones 4 &5). These zones have moderate separation with
accumulation of fines and size distribution curves narrower
than intermediate zones but wider than zone 1.
Increased silica (20:80 mixture) impacts settling and
separation, resulting in broader size distribution curves in
zone 4 compared to 50:50 mixture, indicating improved
separation efficiency due to different force interactions.
Intermediate zones (zones 2 &3) demonstrate the
most effective separation for both magnetite and silica in
the spiral concentrator.
ACKNOWLEDGMENTS
Authors are thankful to UAY, Government of India, TATA
Steel and Indian Institute of Technology Hyderabad for
funding the project.
REFERENCES
Agrwal, P.K., S. Bacchuwar, G.V. Rao, and S.K. Sharma.
2016. “Optimisation of Process Parameters of Spiral
Concentrator for Beneficiation of Iron Ore Stacked
Slimes from Kirandul, Chattisgarh, India.” In IMPC
2016 -28th International Mineral Processing Congress.
Vol. 2016-Septe.
Figure 7. Comparison of mean particle size distributions in different feed proportions of a) magnetite and b)silica in
separation zones
This inverse relationship between the percentage of silica
and the average size of magnetite highlights the impact of
feed composition on the particle size distribution. As the
silica percentage increases in the mixture, the average size
of silica predominantly increases in outer zones, while this
trend is not prominent in inner zones. This reinforces the
idea of hindered settling or liberation from magnetite clus-
ters in the denser mixture. Similarly, with an increase in
the silica percentage, the average size of magnetic particles
significantly decreases in outer zones but is less effective in
inner zones. This is likely due to the dominant influence of
centrifugal force, pushing fine magnetite outwards. Higher
silica content leads to smaller average magnetite size across
most zones, suggesting association and hindered settling as
key factors impacting separation efficiency. Silica size also
shows some variation with changes in feed composition,
potentially due to competition for space, hindered settling,
or liberation from magnetite clusters.
CONCLUSIONS
The overall objective of this study is to explore the compo-
nent interactions along the spiral trough and the effect of
particle separation w.r.t to feed proportion in spiral con-
centrators. The main conclusions can be drawn as follows:
In pure feed streams, magnetite particle size progres-
sively decreases from inner to outer zones (concentration
to tailings) due to centrifugal force, while silica exhibits a
more complex trend with accumulation in zone 1 and then
decrease in size.
Low centrifugal force leads to minimal change in aver-
age size for silica and accumulation of finer silica with
coarser magnetite, resulting in marginal separation and nar-
rower size distribution curves.
Strong gravitational and centrifugal forces effectively
concentrate finer magnetite towards the center and decrease
average sizes for both minerals in intermediate zones (zones
2 &3), exhibiting wider size distribution curves and signi-
fying significant separation zones.
Strongest centrifugal force directs finest magnetite to
tailings and reduces silica size significantly in outer zones
(zones 4 &5). These zones have moderate separation with
accumulation of fines and size distribution curves narrower
than intermediate zones but wider than zone 1.
Increased silica (20:80 mixture) impacts settling and
separation, resulting in broader size distribution curves in
zone 4 compared to 50:50 mixture, indicating improved
separation efficiency due to different force interactions.
Intermediate zones (zones 2 &3) demonstrate the
most effective separation for both magnetite and silica in
the spiral concentrator.
ACKNOWLEDGMENTS
Authors are thankful to UAY, Government of India, TATA
Steel and Indian Institute of Technology Hyderabad for
funding the project.
REFERENCES
Agrwal, P.K., S. Bacchuwar, G.V. Rao, and S.K. Sharma.
2016. “Optimisation of Process Parameters of Spiral
Concentrator for Beneficiation of Iron Ore Stacked
Slimes from Kirandul, Chattisgarh, India.” In IMPC
2016 -28th International Mineral Processing Congress.
Vol. 2016-Septe.
Figure 7. Comparison of mean particle size distributions in different feed proportions of a) magnetite and b)silica in
separation zones