In this study, a three-level Box–Behnken factorial design combined
with response surface methodology was employed for modeling the
HTRS to concentrate conducting minerals. The three process variables
considered in this study were temperature of the feed, feed rate and
roll speed. The mathematical models were developed for both grade
and recovery of the titanium bearing minerals in the conducting
fraction by using sets of experimental data and mathematical
software package Matlab 7.1. The predicted values obtained using
the models were in very good agreement with the observed values (R2
value of 0.94 for the grade and 0.83 for the recovery of titanium
minerals in the conducting fraction). From the quadratic programming,
optimum levels of the process variables have been determined
for achieving maximum grade and recovery. The maximum grade that
can be achieved is 98.7% which is 1.1% higher than that of observed
values, at the feed temperature of 140 °C, feed rate of 2.5 tph and roll
speed of 120 rpm whereas the maximum recovery that can be
achieved is 98.4% which is a 2.4% improvement compared to the
observed value, at 109.4 °C of feed temperature, 2.5 tph of the feed
rate and 180 rpm of the roll speed. In order to accomplish better
understanding of the process variables of the HTRS on grade and
recovery of the titanium minerals in the conducting fraction, the
predicted model