The use of perlite as a filter aid has been studied for the separation
of tincal insolubles from borax solutions during the dissolution of t
incal concentrate. Precoating and body-feeding techniques were applied
with perlite/insolubles ratios ranging between 0-3 with filtration pr
essures ranging between 2 and 4 bar. Lower specific cake resistances o
f the order 1 x 10(10) m kg-1 were obtained for the body-feeding techn
ique. Incompressible cakes were obtained with compressiblity coefficie
nts of c. 0.016. The specific cake resistance was found to increase wi
th the bulk density of the perlite grade.