PARTICLE TECHNOLOGY
 

Look Up Table for specific resistance and concentration

Look Up Table for specific resistance and cake concentration of common materials and how they are influenced by the filtration pressure (D Pc).

The equation for average specific resistance (alpha) is:



and, likewise, for cake concentration by volume fraction:



where a o ,C0, n and u are empirically derived constants.
Published values for constants used in above equations

Material

Resistance

at 1 bar

(m kg-1)

a o

(m kg-1 Pa-n)

n

Co

(Pa-u)

u

100 m m glass beads*

0.064 x109

0.064 x109

0

0.60

0

10 m m glass beads*

6.4 x109

6.4 x109

0

0.60

0

Alumina

5.2x109

2.37x108

0.3

0.07

0.066

Calcium carbonate

in salt solution

18.2 x109

46.9 x108

0.13

0.22

0.03

Fine calcium carbonate

in water

71 x109

89.3 x108

0.2

0.09

0.1

…end of vacuum filtration range

          

Coarse grade kaolin

71 x109

4.5 x108

0.5

0.15

0.08

Talc in salt solution

112 x109

7.1 x108

0.5

0.008

0.29

Talc in water

112 x109

7.1 x108

0.5

0.088

0.144

Titanium dioxide

344 x109

127 x108

0.32

0.06

0.13

1 m m glass beads*

640 x109

640 x109

0

0.60

0

Cement

491 x109

222 x108

0.3

0.33

0.05

Kaolin (Hong Kong pink)

1025 x109

64.8 x108

0.5

0.17

0.08

zinc sulphide pH 3

1300 x109

1000 x108

0.25

0.19

0.06

…end of pressure filtration range

          

Magnesium hydroxide

1600 x109

135 x108

0.47

    

Aluminium hydroxide

11000 x109

3320 x108

0.34

    

Stable zinc sulphide

47000 x109

148 x108

0.92

0.002

0.39

Colloidal clay

63000 x109

1440 x108

0.61

    
* assuming a random close packing and using the Kozeny-Carman equation

If you would like to calculate a value for specific resistance at your filtration pressure then enter values in the following boxes, using the table values or practical data, and press the calculate button:

a o    (m kg-1 Pa-n)
n
pressure drop over the filter cake (Pa)

SELECT       OR YOU CAN       THE ABOVE VALUES

postscript
If you want to know how the average mass of dry cake per unit volume filtrate is obtained from the average cake concentration and the mass fraction of solids in the feed slurry then the following formula is useful. Hence, the filter cake forming pressure influences the volumetric cake concentration and the dry cake mass in a way given by the equations on this page.
   

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