this greenfield site by conducting a pilot plant
study. The pilot test took place at a different
operating iron plant about 200 km from the new
plant. The P&TT type underflow was produced in
a 1 m WesTech pilot plant, and the underflow
angle of repose was studied in 1 m by 10 m
troughs constructed of sheet metal. The pilot
plant results showed that an underflow of about
73 wt% solids is possible with a P&TT underflow
that produced a 2-3% angle of repose upon
deposition.
Parameters such as particle size distribution,
PSD, mineralogy, and water chemistry, vary from
site to site and will change the yield stress
versus solids wt% relationship. The parameters
for each site must be known. The Baotou plant
produced the designed yield stress and stacks
with an acceptable angle of repose, but the
associated wt% solids was 70-71 wt%.
The Baotou site uses a high rate thickener
located at the plant. This thickener underflow is
pumped 2.6 km to the 20 m diameter WesTech
Deep Bed™ paste thickeners located near the
deposition site. The P&TT tailings are then
pumped 0.5-2.9 km to a set of spigot discharge
points along the containment dykes. The
impoundment is in a shallow valley with the
boundary structure on the downhill sides.
The water balance of this site is provided in
the attached table. The over 8,000 m 3 /h tailings
stream is dewatered in the high rate thickener
Water balance around the two-stage thickening circuit at Baotou Steel
Stage
WesTech High Rate
Thickener
WesTech Paste
Thickener
Water in
Feed, m 3 /h
8,335 Water in
Overflow, m 3 /h
7,460 Water in
Underflow, m 3 /h
875 Stage
Recovery
89.5%
875 518 357 59.1%
to 45-50 wt% solids and recovers about 90% of
this water. The paste thickener recovers an
additional 5 percentage points (518 m 3 /h, which
is about 20% of the Yellow River water pipeline
flow). Recovering the water at the paste
thickener prevents this loss of any of that water,
like in a slurry pond. The water recovered at the
thickener has excellent clarity
with <50 ppm and is recycled to
the process.
standing water on the surface, greatly reducing
environmental risk. Producing higher underflow
density benefits systems such as CCD circuits
and filtration. The reduction of water in the
underflow makes the CCD stage more efficient
and can reduce the hydraulic load when feeding
a filter.
Conclusion
An important benefit of P&TT
technology is improved water
recovery. The water is recovered
at the thickener while producing
a non-Newtonian suspension
underflow that achieves a
higher final density of the
tailings, and the overall
recovery is increased. The
tailings storage facility (TSF) has little or no
Reliable Heavy Duty
Slurry Pumps
The 90 m High Rate Thickener at Khumani
MHWirth is a pioneer in slurry pump technology and has
been manufacturing piston diaphragm slurry pumps
for more than 45 years. More than 1 000 positive
displacement pumps have been built with power ratings
of up to 3 000 kW.
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SFBMUJNF81.4uQVNQ
NPOJUPSJOHTZTUFN
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by up to 15 %.
Our pumps perform successfully in numerous projects
worldwide in various applications:
Ŷ Tailings transport
Ŷ 1JQFMJOFTMVSSZUSBOTGFS
Ŷ Autoclave digester feed
Want to learn more?
Visit us at Expomin at booth no. 2-B08
mhwirth.com