The Korean distomaceous earths as a filter aid is under the research. The American Decalite Speedplus as a standard to be compared with the natives was precoated on two kinds of filtermedia to filter the dilute calcium carbonate slurry.
The one filter-medium, glass filter, was used, but had poor reproducibility of its glass pores.
The other filter-medium, a Buchner filtering funnel covered with a kind of plain-weaved nylon cloths, was appreciable for the vacuum filtration of the slurry. The mean specific cake resistance α and the filter-medium resistance R for these media were observed in the range of the slurry concentration from 0.1 % to 1.0 % by weight.
According to the gradual increasing of the CaCO₃ slurry concentrations, the mean specific cake resistance α are decreased and the filter medium resistances R are increased. As far as the thickness of the filter cake formed is of the range from 0.4 cm to 1.5 cm, the R/α ratios for the non-precoated glass filter are varied from 0.10 to 0.30, for the non-precoated nylon cloths and Buchner funnel ; from 0.05 to 0.40, and for the precoated nylon cloths and Buchner funnel ; from 0.05 to 0.20, respectively.