Electrolyte cleaning

Separation of metal hydroxides

EnviroFALK sets new standards in the separation of metal hydroxides using specially developed ultrafiltration systems.

In electrochemical metal machining (ECM), metal ions are dissolved from the workpiece. The removed material, which settles as metal hydroxide sludge, must be filtered out of the electrolyte solution.

Conventional method: metal hydroxide via chamber filter press
Here, the metal hydroxide sludge is passed through a chamber filter press.
Disadvantage: The metal hydroxide sludge is so fine that no filter cake is produced in the chamber filter press, but rather a thin liquid mass that requires intensive daily cleaning of the chamber filter press for approx. 1 hour. This cleaning is carried out by additional personnel or the operator of the ECM machine, resulting in daily production downtime.

Solution concept: Separation of the metal hydroxides by ultrafiltration
The ultrafiltration system specially developed by EnviroFALK for electrolyte purification conveys the contaminated electrolyte from the dirt tank of the ECM system and circulates it through the special capillary membranes of the ultrafiltration system. This removes all impurities from the electrolyte. The purified electrolyte is then fed back into the clean water tank of the ECM system.

For comparison: The ultrafiltration membrane for cleaning the electrolyte solution has a pore size of 0.03 µm. A sterile filter, which is often used in water treatment, has a pore size of 0.2 µm.

Depending on the process load, the ultrafiltration membranes are flushed at regular intervals. The membrane is cleaned fully automatically using only the electrolyte and compressed air. No chemicals are used for this special cleaning process. The advantage: Possible contamination of the electrolyte by foreign chemicals is ruled out.

The metal hydroxide sludge produced during this membrane cleaning process is already significantly concentrated by ultrafiltration before it is flushed into a specially developed pointed-bottom tank for further sedimentation. The metal hydroxide sludge thickens further in the pointed bottom tank and is then filtered out via the chamber filter press. The chamber filter press works in bypass mode, whereby the metal hydroxide sludge is slowly and continuously removed from the pointed bottom tank. This mode of operation increases the efficiency of the chamber filter press and leads to excellent filtration results. The resulting filtrate is then returned to the ECM vacuum tank in a closed circuit. The resulting metal hydroxide sludge can be disposed of as a solid filter cake; opening the chamber filter press once a week is usually sufficient.

The convincing track record:
In the ECM process, the ultrafiltration system guarantees consistently high electrolyte quality. All in all, this enables a constantly high utilization of the ECM machine. Another plus: The daily and intensive cleaning effort of the chamber filter press is reduced to a weekly cleaning of approx. 15 minutes. This reduces unproductive downtimes to a minimum. In addition, the puncture-resistant metal hydroxide filter cakes are much easier and cheaper to dispose of.