15. 1. 2023
Improper cleaning of a self-cleaning drawer magnet
Problem
After the installation of any magnetic separator it is necessary to find out how long it takes to reach the limit of the separator's capture capacity (i. e., how quickly the separator gets clogged with ferromagnetic particles) and then determine the optimal cleaning interval. In case of the separators with automatic cleaning, this period is entered as a cleaning interval into their cleaning program and the separator automatically gets rid of trapped iron particles at regular intervals.
However, in this specific case, the operator entered a substantially longer cleaning interval (than that found during the separator testing) that caused three serious problems:
- The magnetic separator was clogged with iron contaminants (and it could not fulfill its function, i.e. separate iron contaminants from the cleaned material) and the contaminated material kept passing through the separator.
- As the separator's capture capacity was reached and the layer of the trapped ferrous particles was so high that the magnetic field could hold them, the flowing material carried them away (into the already cleaned material).
- The amount of the trapped ferrous particles was so huge that even the separator pneumatic system could not pull the magnetic cores out of the protective tubes (at the moment of activation of the cleaning interval). The separator got blocked and had to be repaired by our technicians.
Solution
In case of materials conveyed by gravity, the cleaning interval depends mainly on the degree of ferrous contamination. That is why it is always necessary to stipulate the optimal cleaning interval (= how long it takes to reach the limit of the separator's capture capacity) and this must be strictly observed (for separators with automatic cleaning, this period is entered as a cleaning interval. The separator automatically and regularly gets rid of the captured tramp iron particles at these intervals).
Expert recommendation
Even in case of the separators equipped with a self-cleaning system we recommend that you use shorter cleaning intervals, as the more magnetic particles are accumulated and held by the magnetic core, the more difficult and demanding it is to demagnetize them (i. e. to move them out of the reach of the magnetic field).