By coincidence, I spent a good part of today looking at very powerful magnets to extract needles etc from cut grass! If only we could find the analogue for your problem...
Sure! Although what I posted is quite literal, and the explanation is rather trivial.
Near where I live, a waste collection center sends grass cuttings to a cattle feedstock blending plant, that a business partner of mine has an interest in. The concern is literally needles (syringe type). Currently a conveyor belt running over a magnetic drum is used to remove ferrous materials, but the magnetic field strength is insufficient. The idea is to place powerful rare earth magnets in a grid through which the cuttings would drop, hopefully improving the removal rate.
So we are looking for needles in a future haystack!
