Boonsom Siribumrungsukha, Surasak Treesuwan, and Wittaya Tongsongsom

pp. 273 - 281

Abstract

Asia Mining Company produces feldspar and supplies to both domestic and overseas industries.
Ore from the mine is crushed and ground and then classified by screening. That which is coarsely sized
(+40 mesh) can be sold to the market, while that which is finely sized is left unsold due to the market
requirement that size must be of -40+140 mesh. This research designed and constructed a Vertical Air
Classifier in which the fine mineral is fed to a vertical chamber while air is blown from the bottom. The main
variables are air flow rates and the length of contact between the air and the mineral (at length of 10 and
15 cm). The air is blown in by air compressor and its rate is controlled by a thin plate orifice. Experiments
show that the classifier can eliminate more of the size of -140 mesh as the air flow rate increases. The % fractional recovery at the size of -140 mesh is found to decrease as the air flow rate increases. The length of contact
between the air and the mineral influences the elimination and the % fractional recovery as well. When the length
is shorter (at 10 cm), the elimination of the size -140 mesh is better and the % fractional recovery at the size -140
mesh in the underflow is lower. At the air flow rate of 6.42 L/S and the length of contact of 10 cm, the size of -140
mesh can be reduced from 37.11% in the feed down to 17.70% in the underflow. The results demonstrate the
potential of the Vertical Air Classifier to be further developed in eliminating the size -140 mesh by connecting the
classifiers in series.