A Wilfley-type shaking table separates ore by specific gravity, not size or shape alone. The deck reciprocates along its long axis with an asymmetric (differential) stroke — a slow forward push that accelerates the bed of grains with it, followed by a fast return snap that the denser, riffle-hugging grains cannot fully follow. Each cycle nets a small forward "creep" along the riffles. Grains that settle into full contact with the deck get strong traction from this creep; grains riding higher in the flowing water film get carried across the deck instead by the cross-slope wash water.
Because cassiterite (SnO₂, specific gravity ≈ 6.8–7.1) is roughly 2.6× denser than the silicate gangue (SG ≈ 2.65) it is mined with, it settles into the riffles and rides the differential-shake creep down the table, discharging near the head as concentrate. The lighter gangue stays suspended in the water film and is swept sideways by the wash water, fanning out to the tailings edge. Increasing wash water flow or cross-slope pulls more material — including some tin — into the tailings; increasing shake speed strengthens the riffle creep for everything, raising throughput but eventually dragging fine gangue into the concentrate too.
- Concentrate zone — high-traction band nearest the riffled head, where dense grains discharge.
- Middling zone — mixed material, typically recirculated on a real table.
- Tailings zone — far cross-slope edge, dominated by light gangue swept by the wash water.
- Recovery / grade — the two standard metallurgical KPIs: recovery is the fraction of fed tin reporting to concentrate; grade is the tin content of the concentrate stream itself. The two trade off against each other as the controls change.