Trace metallic iron in cathode powder is one of the few contaminants that can turn into a safety problem rather than just a quality problem. A particle small enough to pass a screen can still bridge the separator inside a cell, create a local internal short, and become a heat source during charge and discharge.
This is why cell makers treat magnetic content as a controlled variable, not a cosmetic one. Iron enters from several places: worn milling media, corrosion in slurry tanks and pipes, and raw material carry-over. Because the sources sit along the whole line, control is more effective as several de-ironing stages rather than one filter at the end.
In practice, powder-stage de-ironing uses dry high-gradient electromagnetic separators that pull weakly magnetic particles out of free-flowing powder without adding moisture or changing particle size distribution. Slurry-stage units handle the wet side, where the material is already dispersed and magnetics are easier to liberate.
Because every powder behaves differently, we recommend starting with a free sample test: send the material, and we return a measured iron-reduction result on the same equipment you would buy. That turns a specification into a number you can write into your own process control.
Working on a similar material?
Send us your material and target — we run a free sample test and return the iron-reduction result before you commit to a machine.