Autogenous grinding is a process of grinding ore in a rotating cylinder using large pieces of the same ore. Autogenous mills operate mechanically like ball mills; however the media used for grinding differs.
Autogenous Mills operate mechanically similar to the ball mill. They differ in the media they use to break or grind the ore. Autogenous Mills use large particles of ore instead of steel or other balls for grinding media. Autogenous mills use large pieces of ore as grinding media.
In autogenous grinding a distinction is made between ore and ore-pebble grinding. Ore grinding is carried out in mills with a large diameter (up to 12 m) and short length (the ratio of diameter to length is approximately 3). Ore with pieces having dimensions up to 300 mm (sometimes up to 600 mm) is loaded into the mill.
Autogenous mill Autogenous or autogenic mills are so-called due to the self-grinding of the ore: a rotating drum throws larger rocks of ore in a cascading motion which causes impact breakage of larger rocks and compressive grinding of finer particles.
Autogenous grinding is favored when the ore is quite competent and a fine grind is required. Semi-autogenous grinding is applied when fine crushing could cause severe problems or when ore is variable in hardness or competency.
In conventional milling the ore is crushed to plus or minus 3/8 of an inch before it is put into a mill for grinding. In a autogenous mill the ore is fed directly into the mill from either the primary crusher or the mine itself. The size of the rock will be between four and eight inches.