The nominal design capacity of the
proposed flotation facility was 236 tph
(ad) of fresh feed.
The process design and plant layout
developed as part of the feasibility
study include:
n
Two 2.4 m wide x 6.1 m long low
head single deck spirals product
dewatering screens (brownfield
addition to existing plant).
n
Four 8 m dia., 32 downcomer
Jameson Cells in a primary and
retreat duty.
n
One 18 m dia. coal thickener.
n
Two 140 m
2
hyperbaric disc filters
and the process air compressor
package.
n
Ancillary services.
The plant process flowsheet and a 3D
Navisworks view of the proposed
facility are provided in Figures 7 and 8.
For a hyperbaric filter, a filtercake
free moisture of approximately 18%
(supported by the OEM testing) leads to
a projected 71 tph (ad) production
increase, or a plant yield increase of
3.5% (ar). Although there is a minor
increase in total CPP moisture from
9.4% to 9.8%, there is an associated
reduction in overall product ash from
13.0% down to 12.3% (ad). As such, the
gross/‘wet’ energy of the saleable
product will increase slightly.
The hyperbaric disc filter will require
140 Nm
3
/t (or 22 400 Nm
3
/hr) of
process air with a delivery pressure of
0.6 MPa to achieve the target filtercake
total product moisture of 20% (ar).
The total annual operating costs
(2013 basis) for the new plant is
projected to be AUS$5.90/t of flotation
feed. The projected operating costs in
this study is significantly less than for
the New Zealand metallurgical coal
study, given there is no requirement for
steam addition (and the associated high
operating cost of the diesel fired steam
boiler).
This project is currently on hold
due to a freeze on new capital projects
at site.
Relative costs of
dewatering technologies
The equipment costs, required drive
power and expected moisture outcomes
from a subset of the various dewatering
options considered in the studies are
Figure 7. New South Wales thermal plant upgrade – flowsheet.
Table 2. Relative capital and operating costs of dewatering technologies considered in the preliminary process selection studies
Dewatering
equipment
Qty Size
Total equipment
cost (AUS$/k)
Total installed
power (kW)
Equipment power
cost (AUS$/t)
Boiler diesel cost
(AUS$/t)
Free moisture (% ar)
Screenbowl centrifuge 3
50 tph
max
1500
950
0.38
-
26.0
Vacuum disc filter
2
176 m
2
3200
960
0.38
-
27.0
Hyperbaric disc filter
–
air only
2
140 m
2
7800
2200
0.88
-
18.0
Hyperbaric disc filter
–
air + steam
1
84 m
2
5100
1780
0.70
9.44
13.0
Figure 8. New South Wales thermal coal flotation upgrade – Navis model.
June 2015
|
World Coal
|
73
