Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal

Dewatering: Thickening, Filtering, CCD, Water Treatment & Tailings Disposal

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Press filter cloth washing (4 replies and 1 comment)

H
Hamid72
6 years ago
Hamid72 6 years ago

Hello everybody

What is the best method for cleaning and washing press filter cloth to reuse.

Which solution clean better the cloth?  

Our particles are mostly  chalcopyrite.

Thankyou

I
Agricola
6 years ago
Agricola 6 years ago
1 like by David

If blinding is due to chalcopyrite concentrate particles embedded in the cloth, you should be able to remove it by washing with a high-pressure water spray.  

Cloths on traditional plate and frame pressure filters are rarely washed effectively by in-situ sprays, which merely flush the cloth surfaces.  The cloths will most likely have to be removed and washed individually on a suitable frame with a high-pressure spray.

Moving cloths on automatic pressure filters or "tower presses" are washed efficiently in the filter as they pass through high-pressure sprays.  They usually give much longer cloth life, and cloth is normally the highest operating cost factor for pressure filters.

High-pressure water sprays can often remove chemical precipitates, but sometimes the cloths must be removed and soaked in a solution that can dissolve the precipitate.

 

H
Hamid72
6 years ago
Hamid72 6 years ago

Thanks Agricola 

do you know what is the best solution for this purpose?

C
czambrano
6 years ago
czambrano 6 years ago
1 like by David

Hello Hamid72,

As Agricola stated, I experienced a little improvement in high pressure water spray but in horizontal filter plates which is easier with a Karcher machine or similar. I saw in a ceramic filter plant that they atack Cu & Fe with Oxalic acid at 2-5% solution, and as an external service with 1% nitric acid. It depends on the cloth fiber materials and my recommendation would be to identify the cause of blinding and try a test with one piece of cloth and see the results. Usually a dedicated spyglass for this use could help on this.

H
Hamid72
6 years ago

Thank you so much

D
pepperd
6 years ago
pepperd 6 years ago
1 like by David

Cloth washing options depend very much on the size of the filter press / filter plates.  On 470mm or 630mm filter plates, there is likely no cloth wash system, and washing would be done manually, either with the plates in-situ or removed.

On 800mm filter plates, you might find a press with a cloth wash system installed.

On 1200mm plates and larger, it would be common for some type of cloth washing system to be installed.

For fast moving filter presses, the modern choice for concentrate applications, all the plates are linked together and open almost simultaneously.  There is no way to wash the plates individually, and so each plate has a spray bar.  The purpose is mainly to rinse away pieces of filter cake that did not discharge, so that the plates close without sealing issues.  These pieces of cake, if located at the sealing surface, will cause poor sealing and leaking of slurry during subsequent filling step.  In this case, cloth washing, or rinsing, will happen every cycle.  The water flow rate will be high and the pressure will be low.  This will not be very effective for unblinding cloths, but that is not the purpose of this cloth rinsing.

For slower moving filter presses, where the plates are not linked together, but instead shifted one by one, or two by two, you can have a cloth washer installed.  This device washes one or 2 cloths at a time, with high pressure, low flow rate.  This is very effective for unblinding filter cloths, but is very slow process, maybe 1-2 min per plate.  This means it is done at most every 3rd cycle, but more typically once per day or once every other day.

The above is basically applicable for side bar filter presses.  For overhead beam filter presses, the plates are never linked together and the individual cloth washing system is the only option.

If you have a sidebar filter press with linked plates, then you should focus on cloth selection and finding one that does not blind before it wears out due to abrasion.  You might also play around with feed pump pressure during filling - in some cases, filling at high flow rates initially can cause blinding and hence the pump flow rate needs to be regulated to increase cloth life.

If you have a tower filter press, with horizontal plates, stacked vertically, then generally a high pressure wash system is installed, operates every cycle, and is quite effective for unblinding filter cloths.

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