Dressing is the concentration of the tin (copper or other ores) contained in the rock excavated from the stopes of a mine. Carried out on Dressing Floors
The Dressing Floors were an often extensive area at surface on a mine. The ore was cancentrated by crushing or stamping to attain a uniform size range, sizing (particularly on later mines), separation of waste rock, concentration (generally mechanically and hydraulically on tin mines, manually on copper mines), the removal of contaminant minerals (by calcination, flotation, magnetic separation), and finally drying and bagging for transportation to the smelter.
Tin floors in particular were generally laid out down a slope to reduce mechanical or manual handling between stages in the process.
Sometimes a Shaking Table was used to separate out the ore from the waste rock. An inclined, mechanically vibrated table on which fine tin (as sands or slimes) in suspension in water was concentrated by relative density. Other ore concentration methods are discussed here.
A Bal Maid was a woman or girl employed at surface on a mine, in the dressing of ore.
Mines and Mining In Cornwall