Consolidation compression deliquoring phase

The cake consohdation period proceeds by using the flexible diaphragms at a pressure of 600 kPa and is specified to last for the same duration as the two cake formation stages (i.e. 1418 s). Noting that the consohdation pressure (ApJ in the scale-up equations for Q and has units of kPa and the active filter area 

Noting that the subscript pr indicates a value from the end of the secondary filtration phase and the mass of solids in the cakes remains constant throughout consolidation and equal = 4527 kg, the data sequences shown in Table 6.7 provide information for the consolidation phase where  

Assuming that it is economical to continue cake consolidation until = 1418 s, the end of phase values are given in the bottom line of Table 6.7 where the total cycle time is = 2836 s and the final cake thickness (L ) = 0.0383 m. In order to facilitate calculations for the remaining phases in the cycle the average solids volume fraction and specific resistance of the cake in each chamber needs to be determined. The former is given by equation (6.47) 

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Table 6.7 Data sequences for the consolidation (compression deliquoring) phase of a diaphragm press cycle.

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. 

Compression deliquoring Parameters specific to a consolidation phase including compression pressure, consolidation index, two scale-up coefficients for cake solids concentration and two scale-up coefficients for consolidation coefficient. 

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