Environmental Engineering Reference
In-Depth Information
•
G
f
is the feed ore flow to the rod mill, with size
f
80
;
•
G
k
is the product flow from the rod mill, with size
k
80
;
•
G
p
is the plant product ore flow, with size
p
80
;
•
P
eR
is the power draw of the rod mill;
•
P
eB j
is the power draw of the ball mill in section
j
(
j
=
1
,
2
,
3
)
;
∑
j
=
1
P
eB j
is the total power draw of the mills.
The variables
f
80
,
k
80
and
p
80
are the sizes for which 80% of the ore has a smaller
size, at the points shown in Figure 4.21.
•
P
T
=
P
eR
+
Time [min]
Figure 4.18
Test of soft sensor 2 in 2.4 days of month 1 using parameters determined on a dif-
ferent day of month 1. Shown is the actual sensor measurement (black) and the soft sensor output
(segmented)
A global operational work index
W
iog
was defined for the grinding plant of Figure
4.21 - following the definitions of operational work indexes for rod mills and ball
mills - as
/
P
t
G
f
=
)
,
W
iog
(4.142)
f
80
−
1
/
2
p
80
−
1
/
2
11
.
02
F
TG
(
−
where
F
TG
857 [24].
From (4.142), there are four variables determining
W
iog
. On the one hand, the
on-line measurements of two of them are almost always available; power
P
T
is mea-
sured by highly reliable wattmeters, and ore flow
G
f
measures the throughput of
the plant so it is maintained to provide a highly reliable measurement. On the other
hand, neither
f
80
nor
p
80
are measured. However, for this plant a relation has been
found linking
p
80
with measured
g
65
giving +65# particle size percentage (percent-
age weight of particles larger than 210 μm). This relation is
=
0
.
p
80
=
1
.
78
+
10
.
07
g
65
.
(4.143)
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