
219Metal Refining and Purification
molten metal. CFFs can be produced with a range of pore sizes and cost less than
other lters (DeYoung, 1999). However, they are less efcient than other lter
materials (Fielding, 1996), limiting their usefulness. Figure 12.14 shows a com-
mon arrangement, a staged CFF (Aubrey and Smith, 1999; Chesonis et al., 2002).
In this arrangement, a coarse lter occupies the top slot in the lter frame, and a
ner-pore lter the lower position. This improves capacity and improves capture
efciency for smaller inclusions.
Considerable efforts have been made in recent years to improve CFFs. The choice
of ceramic material has ...