Behaviours of Various Kaolin Slurries in Constant Pressure Filtration (about Hongkong Kaolins, "Pink" and "Dark yellow, " and Shinmei Kaolin)

Abstract

In order to study the filtration characteristics of Kaolin slurries, a number of experiments were conducted in constant-pressure filtration, and measurements of the hydraulic pressure variations within actual filter-cakes at constant-pressure filtration (using air-sealed manometers) and compression permeability experiments (using a consolidometer) were made.The results may be summarized as follows:(i) The Ruth's coefficients K20 obtained from Eqs. (3) and (4) showed deviations of less than 10% from the actual filtration results K20f.(ii) The values of m obtained from Eq. (4) showed good agreement with m′ obtained from Eq. (4′), as revealed in Table 3. Consequently, it may safely be concluded that so far as Kaolin slurries are concerned, experiments in constant pressure filtration besides mere compression tests would be enough to make clear the behaviours thereof.(iii) The specific resistance αf of the constant-pressure-filtration cakes of Kaolin slurries proved to be a function not only of P but also of s and V.(iv) By the direct measurements of liquid pressure distribution in the cakes under constant-pressure filtration, the cake thickness L was observed to be exactly linear with the filtrate volume V, as shown in Fig. 7. m″ obtained from Eq. (10) was nearly equal to m or m′.(v) Liquid pressure distribution as measured by using air-sealed manometers showed closer approximation to Px vs. x′/L curve obtained from Eq. (7′) as shown in Fig. 6-1, rather than Px vs. x/L curve obtained from Eq. (7).