S. MOHANAN ET AL.
1010
output index—Operational Quality Index (OQI)—has
been applied successfully to optimize input parameters
for efficient operation. Statistical models were developed
for OQI, as well as both grade and recovery of the con-
ducting minerals individually. The predicted values ob-
tained using the models were in very good agreement
with the observed values (R2 value of 0.91 for OQI;
similar values obtained for both grade and recovery).
Process optimization, viz. maximization of OQI has been
done by keeping the constraints of grade >96% and re-
covery >98%. The maximum value of OQI obtained un-
der the given constraints is 195.53, at the following oper-
ating conditions—Temperature: 102˚C, Feed Rate: 1.75
tph and Roll Speed: 132 rpm. Under these operating
conditions, the grade and recovery obtained are 96.6%
and 98.9% respectively. Normally, the separation effi-
ciency index, which is a % recovery from the formula, is
associated with coal washing processes; while coefficient
of separation is nothing but an index derived from reco-
very/distribution percentages of concentrates and rejects.
Though these indices are useful in predicting the process
performance, using the quality and quantity of different
fractions, these are not completely significant for process
variable optimization studies. Therefore, it was found
that the concept of OQI is simple and more reliable in
this regard.
5. Acknowledgements
Authors are thankful to Tata Steel Ltd management for
the support and permission to publish this work.
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