3
exponent from this signature plot is the “Hukki exponent”
(–α).
The ‘Ktest’ value of a test that requires correction is
first computed using Equation (5), then the corrected
work index is computed using Equation (6). The ‘K’ values
should be reasonably constant for a sample in the size range
being examined, so is independent of a test’s product size.
Ktest P
Wi P F 10 .
test
test test test
0 5 ##
=
-
-a
--0.5 _i
(5)
Wi
P F
K P
10 .corrected
desired test
test test
0 5 #
#
=
---0.5
-a
_i (6)
Correction for Incorrect Product Size (Morrell Mib)
The algorithm is the same, except that the reference sample
must use the Morrell (2008) Mi Equation (7) to generate
the signature plot. The resulting correction Equations (8) &
(9) are obtained using the same methodology as for Bond.
E P 4Mib
test
P Ftest
test test test
0.293
10 10
test
6 6 #=---0.293 `j 6 6F @@(7)
K Mib
P
4P
test test
test
Ptesti
test
Fh
0.293 10
0.293 10
#=
-P
a
-
-
-6
-6
f
_-
^-
p (8)
Mib
P
K P
4f
.0293
.0293
corrected
desired
P
desired
F
desired
desired$10
desired$10
#
=
-F
-
-
-a
-6
-6
^-
^-
p
h
h
(9)
Figure 1. Database of Bond ball mill work index tests plotted against simplified principal components
Figure 2. Database of Morrell Mib tests plotted against simplified principal components