Validation of a new filtration technique for dewaterability characterization

Characterization of the compressibility and permeability of flocculated sus pensions is a time-consuming experimental process that often takes days to perform. A new pressure filtration method developed characterizes a sample only in hours. Using stepped pressure sure filtration, the compressive yiel d stress P-y(phi) and a hindered settling function R(phi) of flocculated su spensions are determined as a function of the solids volume function phi. T raditional pressure filtration experiments involve the pressure filtration of a particulate suspension in which the time of filtration t is monitored as a function of piston height from which the specific volume of filtrate V is determined. P-y(phi) is determined from the equilibrium solids volume f raction. The gradient d(t/V)/dV is traditionally used to determine R(phi) u sing a suspension filtration theory developed by Landman and White. The new method uses only one stepped pressure compressibility filtration test and one stepped pressure permeability filtration test to determine P-y(phi) and R(phi) for multiple solids volume fractions and substantially decreases th e time requiredfor sample characterization. To eliminate the influence of a stepped pressure on calculated permeabilities, the analysis of experimenta l results was modified using the gradient dt/dV(2). Results are presented f or. a zirconia suspension comparing both single and stepped pressure filtra tion.