XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 545
favorably with the AG/Ball circuit which only requires an
open circuit primary crusher. In terms of crusher circuit,
this compares more favorably to High Pressure Grinding
Roll (HPGR) preparation which requires closed circuit sec-
ondary crushing to 50 or 60 mm top size in order to protect
the tungsten carbide roll studs.
VRM 3D PLANT LAYOUT DESIGN
Based on the successful test campaigns the flow sheet and
hence the plant layout was changed from AG/BM to VRM
comminution. The plant layout is illustrated in Figure 7
and Figure 8.
Followed by primary and secondary open circuit
crushing the ore is feed to two parallel VRM circuits with
integrated RMS. Each of the VRM circuits is operated
individually to allow for maximum flexibility during opera-
tion and separate maintenance schedules for each plant.
The RMS plant, shown on the left side of Figure 7
is integrated into the VRM circuit. The Fe-enriched fine
product of the VRM circuits reports to the product silo
while the dry non mag tailings are discharged from the cir-
cuit to be stacked or blended with the wet fine tails.
A benefit of the dry grinding product is that it provided
the capability to easily store it in product silos with much
higher capacities, and without agitation compared to wet
stirred storage tanks. VRM technology allows 24 hour or
more buffer ahead of downstream processing. Large prod-
uct silos, if installed, substantially increase the decoupling
of the dry comminution and the wet process circuits. One
advantage is that the comminution and wet process can be
optimized without interfering with each other. Another
advantage is that maintenance on one of the grinding
plants can be carried out without affecting the downstream
process capacity, as the missing capacity is compensated by
the product silos.
TAILINGS CHANGES
The dry circuit prompted some changes in tails handling,
the biggest being the ability to dry stack the dry tailings
generated from the VRM /Dry magnetic separation cir-
cuits, being relatively coarse sized materials.
This resulted in a substantial reduction in wet tailings
storage footprint, although the sulfide flotation concen-
trate, still requires a storage system to contain the sulfide
minerals extracted in order to produce a Magnetite concen-
trate that would be accepted as a DRI feedstock.
Further reductions of the wet tailings in an order of
magnitude can be achieved by the possibility to mix the
dry VRM non-mag tailings with the thickened fine tailings
produced in flotation. The resulting material mixture with
13% moisture can be conveyed and trucked to tails stack-
ing or be used elsewhere for construction purposes.
SUSTAINABILITY
Energy Efficiency and Environmental Sustainability
The design of the processing plant was focusing on maxi-
mizing process and energy efficiency. This will be achieved
through a number of measures, including the use of
Figure 7. Southdown plant 3D layout, VRMs and bag houses center, RMS =Rougher Mag Sep, IMS =Intermediate Mag Sep,
CMS =Cleaner Mag Sep
favorably with the AG/Ball circuit which only requires an
open circuit primary crusher. In terms of crusher circuit,
this compares more favorably to High Pressure Grinding
Roll (HPGR) preparation which requires closed circuit sec-
ondary crushing to 50 or 60 mm top size in order to protect
the tungsten carbide roll studs.
VRM 3D PLANT LAYOUT DESIGN
Based on the successful test campaigns the flow sheet and
hence the plant layout was changed from AG/BM to VRM
comminution. The plant layout is illustrated in Figure 7
and Figure 8.
Followed by primary and secondary open circuit
crushing the ore is feed to two parallel VRM circuits with
integrated RMS. Each of the VRM circuits is operated
individually to allow for maximum flexibility during opera-
tion and separate maintenance schedules for each plant.
The RMS plant, shown on the left side of Figure 7
is integrated into the VRM circuit. The Fe-enriched fine
product of the VRM circuits reports to the product silo
while the dry non mag tailings are discharged from the cir-
cuit to be stacked or blended with the wet fine tails.
A benefit of the dry grinding product is that it provided
the capability to easily store it in product silos with much
higher capacities, and without agitation compared to wet
stirred storage tanks. VRM technology allows 24 hour or
more buffer ahead of downstream processing. Large prod-
uct silos, if installed, substantially increase the decoupling
of the dry comminution and the wet process circuits. One
advantage is that the comminution and wet process can be
optimized without interfering with each other. Another
advantage is that maintenance on one of the grinding
plants can be carried out without affecting the downstream
process capacity, as the missing capacity is compensated by
the product silos.
TAILINGS CHANGES
The dry circuit prompted some changes in tails handling,
the biggest being the ability to dry stack the dry tailings
generated from the VRM /Dry magnetic separation cir-
cuits, being relatively coarse sized materials.
This resulted in a substantial reduction in wet tailings
storage footprint, although the sulfide flotation concen-
trate, still requires a storage system to contain the sulfide
minerals extracted in order to produce a Magnetite concen-
trate that would be accepted as a DRI feedstock.
Further reductions of the wet tailings in an order of
magnitude can be achieved by the possibility to mix the
dry VRM non-mag tailings with the thickened fine tailings
produced in flotation. The resulting material mixture with
13% moisture can be conveyed and trucked to tails stack-
ing or be used elsewhere for construction purposes.
SUSTAINABILITY
Energy Efficiency and Environmental Sustainability
The design of the processing plant was focusing on maxi-
mizing process and energy efficiency. This will be achieved
through a number of measures, including the use of
Figure 7. Southdown plant 3D layout, VRMs and bag houses center, RMS =Rougher Mag Sep, IMS =Intermediate Mag Sep,
CMS =Cleaner Mag Sep