Cake formation phase calculations

The principal objective of an expression test is to determine the compression deliquoring characteristics of a cake. However, the nature of the test allows both filtration and compression characteristics to be determined when the starting mixture is a suspension (i.e. where the solids are not networked or they are interacting to a significant extent). Cake formation rate, specific resistance and solids volume fraction data can be determined for the filtration phase while analysis of a subsequent consolidation phase allows the calculation of parameters such as consolidation coefficient, consolidation index and ultimate solids concentration in the cake. Repeated use of the expression test over a range of constant pressures allows the evaluation of scale-up coefficients for filter sizing and simulation as described in Section 4.7. 

The moisture content is calculated hy equation (6.16). The end of the primary filtration phase, represented hy the final row of values in Table 6.5, is determined from the specification that cake formation with the pump stops when the cake thickness on each filtration surface reaches 20 mm. Although the value is calculated hy equation (6.92), in reality, a point on the pump... 

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