It is important to reduce metal losses associated with the slag in the
blast furnace runner. Insufficient separation gives rise to technolog
ical problems in the subsequent processing of hot metal and slag in ad
dition to the losses themselves. By using a water-oil physical model o
f the blast furnace trough, the flow behavior and the separation effic
iency in the trough were investigated. A series of experiments was car
ried out by changing the process variables such as flow rate of liquid
s, properties of oil (slag), and geometrical design of the trough. The
results indicate that, at constant physical properties, the flow velo
city in the upper stream of the trough is the predominant factor in de
termining the amount of metal carried over with slag. Oil (slag) visco
sity was also found to be an important contributor in the separation e
fficiency. The mechanism for the slag entrainment into the metal phase
was also investigated. The results indicate that the amount of slag (
oil) entrained into metal (water) is mainly determined by the force ba
lance between inertial force in the metal stream, the viscous force, a
nd the gravity force in the upper stream. Because of this mechanism, t
he oil entrainment ratio decreased sharply with oil volume while the e
ffect of total flow rate, water and oil, was comparatively small. In o
rder to extend the results obtained by this modeling study to the actu
al system, a technique of dimensional analysis was also employed. As a
result, dimensionless group correlations which can describe the separ
ation efficiency as a function of process variables and dimensions of
the trough were derived.