The vacuum filtration of the dilute calcium carbonate slurries body-fed with a filter aid of American Decalite Speedplus was experimented by a filter medium, Büchner filtering funnel covered with a kind of plain-weaved nylon cloths.
In the range of slurry concentration from 0.1 to 1.0 % by weight, the filtration constants C and the filter medium resistances R are gradually decreased and increased, respectively, with the increase of the solid calcium carbonate slurry concentrations. And the mean specific cake resistances α are maximized in the vicinity of 0.5 % CaCO₃ concentration. As far as the thickness of the filter cake formed is of the magnitude below 2.0 ㎝, the R/α ratios are linearly increased from 0.2 to 0.4 with the increase of concentrations.
The body-feed ratio "γ" of the CaCO₃ slurry concentration to the filter aid concentration was also discussed with α, R, R/α and C, but these terms except C are not related to γ, only the plots of log C vs. log γ were, to some extent, roughly linearized, and so these relationships will be validly discussed in the closest future.