How a Stamp Mill Works

How a Stamp Mill Works. . , As early as 300 BC, the Greeks use the primary components of a stamp mill - drive wheel, cams, and stamps - for pounding and hauling grain. The concept was adapted to crushing ore and became widely used in America as a gold recovery process. , Typically, mills were powered by steam engines. As the driveshaft turned, the cams rotated, lifting and then dropping the stamps at a rate of 90 times per minute onto the gold ore below. Each stamp weighed about 800 pounds. , Water was added to the battery box in which ore was being crushed. The splashing action created by the falling stamps threw bits of sand and gold against a screen along the front of the box. Larger bits bounced back into the box to be re-crushed, while the smaller particles passed through the screen and were washed down copper tables coated with mercury. The mercury would “capture” and hold the gold, while the lighter sand passed over the dense mercury film to be discarded as waste.