In mining and mineral processing industry, the filter press is always for dewatering the froth flotation concentration or the tailngs. It is very important to choose a proper slurry pump for working with the filter press to get the best dewatering result.

First step,  Let us review the working principle of the filter press

The filter press mainly relies on the application of pressure to achieve solid-liquid separation. Specifically, it uses a  slurry pump to inject mud or suspension into a closed filter chamber formed by multiple filter plates, which are tightly packed under the action of a hydraulic system to form the filter chamber. In the filter chamber, the liquid penetrates through the filter cloth and exits along the filtrate channel, while the solid  are trapped in the filter chamber and form a filter cake.

So we could tell that , the filter press itself only supply the filtration chamber by filter plate and filter cloth. It should adopt a slurry pump to supply the enough pressure for help the filtration process.

Step 2,  Choose the pump specially designed for filter press

The slurry pumps for the filter press with the follow features:

(1) From the large flow in the early feeding period to the high pressure force for a long time in the late pressing period, the motor can not be overloaded.
(2) The performance curve is steeper, with the change of feeding resistance to achieve the automatic conversion of large flow but low pressure to the small flow with high pressure.
(3) Always maintain high pressure without leakage. So we suggest the pump adopt mechanical seals instead of packing seals

Step 3,  Determine pump flow and head

First confirm the size of the filter area of the filter press. The value of the general flow of the feed pump is: the filter area of the filter press *0.5.  for example, you have a 450M2 filter press, the feeding pump flow rate: 450*0.5=225m3/h

The head is determined according to the inlet pressure of the filter press, 0.1Mpa equals 10 meters of head, plus the pipeline pressure loss (that is, the pipeline pressure loss from the pump outlet to the inlet of the filter press). for example, inlet pressure of the filter press is 0.6Mpa, so 6*10=60m, plus the pipeline pressure loss (0~20 Mpa), so the head of feeding pump will be 60~80m.

Step 4,  Determine pump motor power

In step 3, we have got the flow and head of the pump. On this basis, we could calculate the slurry pump motor power according to the following formula.

In this formula:

p:  density of slurry,  kg/m3

g:  gravitational acceleration, 9.8m/s2

Q: flow rate, m3/h

H: head, m

η: Pump Efficiency, value: 0.6~0.8

P : pump power, W

for example in step 2, we have 450M2 filter press, the feeding pump flow rate: 225m3/h, head is 68m, slurry density is 2200kg/m3. Bring the above value into the above formula:  P=(2200×9.8x225x68)÷(0.7×3600)=130900W. So the motor power will be 130.9KW.

Step 5, Select variable frequency motor for the feeding pump

In the modern filter press system electric control system, it always adopt the PLC automatic control. It means the speed of the pump will be connected with the pressure control of the filter press.

For example, the setting value of the filter press filtration pressure is o.8MPa, if the pressure is not up to this value, the pump will continious work and the speed of the pump will increase to supply the enough flow and head to supply the enough pressure. If it is beyond the setting pressure, the speed of the pump will be lower by the automatic control.  So if we select  a variable frequency motor, it will be benefit for the automatic control of the filter press.

Step 6,  Select the material of pump flow parts.

If the slurry is not corrosive or slightly corrosive, the pump flow parts could high chromium alloy. If the slurry has strong corrosion, the flow parts of the pump need to use corrosion resistant materials such as ceramics according to the charactor of the slurry

Note: the above calculation and information is only for reference, the user shall consult the professional slurry pump manufacturer to get the final pump model according to the practical filter press working and installation conditions.


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