Further information:
The dustbin lid experiment took place after a conversation with Clifford Trezise regarding the Cornish "Rag" frame & Cornish "Round frames".
Actualy the Cornish round frame is (similar in principle) to a continuosly operating rag frame, & in many ways the Mozeley frame is in reality a multi decked rag frame but with a slight orbital motion (as used when using the Cornish vanning shovel)
Just as the frue vanner is also a variant of the rag frame, many of the fine partical / gravity concentration equipment works on similar principles. The key to the efficient operation is with the classification of the feed material to them.
Many typs of classifier have been used, but hydrualic classifiers such as the Cornish classifier, or the German Spitzcasten (I may have spelt this wrong) or the more modern R.O.Stokes Hydrosizer with multiple spigots operated be either pressure differenced in fluidised beds or by a series of mechanical cams as with the Jones hydrosizer (one of which being supplied to Red Caves who were treating the Devon great consols dumps for tin in the 1970's) gave excelent classification. Ensuring that particals in a thin film of water on the decks of the various devices had similar hydraulic properties, & gravity would do its work seperating the heavy mineralised particals from the lighter gangue or tails.
With the early Mozeley frames, to change amplitude of occilation, a weight was moved in or out on a rotating arm, with its bearings in the very centre of the frame while frequency of occilation was changed by changing pulley sizes, later varriable speed motors were used. The whole frame being susspended on wires from a static frame. and able to pivot (force being applied by a pnuematic cylinder).
In practice, one the frame had been set up, it was left alone gently occilating & tilting over to wash off the concentrate at regular intervals.
When operating a group of frames, the tilt times were staggered, to give a more regular rate of feed for further concentrating.