3448 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
For tailings disposal, good water recovery can be criti-
cal for maintaining production. In addition, minimizing
the water content also minimizes the volume required for
storage and dam construction requirements. (Reid) There
is also potential for higher solids content tailings to form a
shallow slope, again reducing the amount of dam construc-
tion needed.
Deep Cone Thickening technology was first developed
by Alcan for use in washing and dewatering the red mud
tailings from the Bayer Process. It has been very successful,
and the majority of all new alumina refineries incorporate
the technology. Those plants typically run a couple hun-
dred tons of solids per hour and the DCTs are all 24 m
diameter or less.
One issue with thickeners with a large volume of mud
storage is that the mud storage volume may not be very
efficient. Ideally, the incoming mud would all be in the
thickener for the same period to thicken up. But with the
inefficiency, some mud is in the thickener for a short period,
stays at low viscosity and short circuits down the center to
the outlet. Other mud flows to the outer periphery of the
thickener and stays in for much longer than the target time,
thickening up to a higher density and viscosity, resulting
in high resistance at the outside of the rake and causing
high torque. This is due to the difficulty in generating high
raking capacities in the inner area of the thickener, suitable
for high tonnages.
A concept to improve the raking capacity and deliver
more even mud bed residence time distributions involved
using much larger than traditional inner rake blade. This
inner spiral blade would essentially shift the second rake
blade to connect the first and third blades, resulting in a
much longer blade. This concept has been patented and
CFD modeling was performed to prove the concept and
review the impact on the mud bed residence time. The
resulting residence time distribution was much more consis-
tent and showed great promise in improving performance.
Without the spiral inner blade, some material ratholes to
the outlets very quickly. With the spiral blade, the ratholing
was cut off and delayed the first material leaving the thick-
ener by several hours (Figure 1).
Existing high density/high compression technologies
frequently don’t achieve target densities. A significant num-
ber of large high tonnage thickeners are running where
operators would like higher underflow density but are lim-
ited by the design of the thickening equipment. There are
a number of reasons for this including rake arm design,
raking capacity, floor slope, and torque limits.
As mud thickens, at some point it begins to exhibit
a yield stress or resistance to flow. High-rate thickeners
Figure 1. Inner spiral blade layout versus traditional
For tailings disposal, good water recovery can be criti-
cal for maintaining production. In addition, minimizing
the water content also minimizes the volume required for
storage and dam construction requirements. (Reid) There
is also potential for higher solids content tailings to form a
shallow slope, again reducing the amount of dam construc-
tion needed.
Deep Cone Thickening technology was first developed
by Alcan for use in washing and dewatering the red mud
tailings from the Bayer Process. It has been very successful,
and the majority of all new alumina refineries incorporate
the technology. Those plants typically run a couple hun-
dred tons of solids per hour and the DCTs are all 24 m
diameter or less.
One issue with thickeners with a large volume of mud
storage is that the mud storage volume may not be very
efficient. Ideally, the incoming mud would all be in the
thickener for the same period to thicken up. But with the
inefficiency, some mud is in the thickener for a short period,
stays at low viscosity and short circuits down the center to
the outlet. Other mud flows to the outer periphery of the
thickener and stays in for much longer than the target time,
thickening up to a higher density and viscosity, resulting
in high resistance at the outside of the rake and causing
high torque. This is due to the difficulty in generating high
raking capacities in the inner area of the thickener, suitable
for high tonnages.
A concept to improve the raking capacity and deliver
more even mud bed residence time distributions involved
using much larger than traditional inner rake blade. This
inner spiral blade would essentially shift the second rake
blade to connect the first and third blades, resulting in a
much longer blade. This concept has been patented and
CFD modeling was performed to prove the concept and
review the impact on the mud bed residence time. The
resulting residence time distribution was much more consis-
tent and showed great promise in improving performance.
Without the spiral inner blade, some material ratholes to
the outlets very quickly. With the spiral blade, the ratholing
was cut off and delayed the first material leaving the thick-
ener by several hours (Figure 1).
Existing high density/high compression technologies
frequently don’t achieve target densities. A significant num-
ber of large high tonnage thickeners are running where
operators would like higher underflow density but are lim-
ited by the design of the thickening equipment. There are
a number of reasons for this including rake arm design,
raking capacity, floor slope, and torque limits.
As mud thickens, at some point it begins to exhibit
a yield stress or resistance to flow. High-rate thickeners
Figure 1. Inner spiral blade layout versus traditional