Did some digging into Mining equipment.
The round drum is with holes in it is called a Trommel. It's a common bit of mining equipment used to sort minerals into different sizes. Sorting's done because many later processes such as roasting work on lumps of a particular size. Big lumps are crushed in a mill to reduce their size,while small lumps and powder are agglomerated together.
I don't think Alan's model is for Tin because that process uses a fine powder. Alan's photos suggest ore is sorted by size, not completely crushed.
Many processes involve water like this modern coal plant. It's more elaborate than Alan's model:
Likewise alluvial gold also uses water, so I don't think Alan's model is for gold:
So my guess is a metal like Lead/Silver or Manganese. This machine is for copper.
Dave