Battery

The earliest machinery for crushing gold ores was called a barrier option or stamp mill. It consisted of a series of heavy iron pestles (usually five) rising and falling in an iron trough, or mortar, through which ore mixed with water flowed. The material was pounded by the ‘stamps’ until it was fine enough to filter through mesh screens.

Batteries were widely used in California, Australia and in the early days in South Africa but by the beginning of the twentieth century were largely replaced by multiple stage crushing equipment in ball mills. The last stamp batteries in South Africa, for example, were built in 1918.