Stamp mill

LOC MI0086 QuincyMine TIF 00027a cropStampMill

LOC MI0086 QuincyMine TIF 00027a

StampMillDetail5730

Grabill - Clean Up day at the Deadwood Terra Gold Stamp Mill

Agricola Stamp ore crusher

Geevor waterwheel stamps

Stamp mill is a type of mill used to crush material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation.

Description

A stamp mill consists of a set of heavy steel (iron-shod wood in some cases) stamps, loosely held vertically in a frame, in which the stamps can slide up and down. They are lifted by cams on a horizontal rotating shaft. As the cam moves from under the stamp, the stamp falls onto the ore below, crushing the rock, and the lifting process is repeated at the next pass of the cam. Each one frame and stamp set is sometimes called a "battery" or, confusingly, a "stamp" and mills are sometimes categorised by how many stamps they have, i.e. a "10 stamp mill" has 10 sets.

History

Stamp mills were used by miners in Samarkand as early as 973. They were used in medieval Persia to crush mineral ores. By the 11th century, stamp mills were in widespread use throughout the medieval Islamic world, from Islamic Spain and North Africa in the west to Central Asia in the east. The basic design has not changed by much other than the drive mechanisms.

In the United States, the first stamp mill in the Californian Gold Rush came into use at the beginning of 1850s at Sutter's Mill. Stamp mills were the first mass-produced machine used to crush and grind gold and other minerals. A stamp mill is a large mechanical device used to crush ore and extract the desired metals from the host material. It uses heavy steel stamps to crush and break apart material, releasing the valuable gold from worthless rock, allowing for the extraction of gold for further refining.

Operation

The basic principle of operation involves feeding the ore into a hopper, where it is then slowly fed into the crushing area of the stamp mill. The stamps are repeatedly raised and dropped onto the ore, crushing it into fine sand or pulverized form, depending on the nature of the ore and the desired outcome. Water is often added to the process, both to help with the crushing process and to wash away the finely ground ore.

Types of Stamp Mills

There are many types of stamp mills, some of which are:

• Gravity Mill - uses gravity to feed the ore through the mill.
• Water-powered - uses water to drive the mechanical process.
• Steam-powered - uses steam engines to provide the power to crush the ore.

Applications

Stamp mills were widely used in the mining industry to crush ore. Their applications included gold, silver, and copper mining. With the advent of more efficient processing methods, stamp mills have largely been replaced by more modern machinery, but they can still be found in some locations, serving as historical artifacts or as operational machines for small-scale mining operations.

Preservation

Many stamp mills have been preserved as historic artifacts, and some are even operational in tourist attractions where visitors can see and hear the mills in action. These preserved stamp mills offer a glimpse into the past and demonstrate the industrial history of mining.

See Also

• Mill (grinding)
• Mining
• Gold mining
• Ore