A quick search on electrostatic precipitators (another name for filters) for incinerators yields lots of results, but no details. My guess is a few thousand to 20K volts DC. You might rig it as an upside down van de Graff and let the particles carry the charge. Maybe if you go that route, you could use magnetic coils to cause the deflection.
Your original question was whether we thought it was feasible. I have no practical experience in building such separators. Sorry.
Can you do this in an inert atmosphere? Flour dust can be explosive.
Have you considered differential, continuous centrifugation? Places that do lots of particle blasting for cleaning and metal prep have "reclaimers". These are basically centrifugal blowers. The heavy particles settle down and the lighter go out the exhaust. A 2-stage setup would potentially give heavy, medium, small and dust.
John