Siemens shakes up ore grinding

Siemens has developed a mechanism which adds a shaking action to ore grinding mills, preventing large stones from blocking the mills and stopping production.

Ore grinding mills are drums the size of houses in which ore for the production of metals is crushed. Big stones, however, frequently block the mills and workers have to break them down by hand or by using pneumatic hammers.

Known as the Frozen Charge Shaker, the system from Siemens uses a gentle forward and backward motion to remove ore from the inside of the drum. This reduces downtime and increases availability, in part because the large rocks can no longer damage the mill.

Siemens is installing the first units of this new system into two mills that are scheduled to go into operation next year in the Lumwana copper mining district of northern Zambia. The ore-grinding mills are semi-autogenous grinding (SAG) mills with a drive output of 18MW. The chunks of ore are initially crushed in a 12m rotating mill drum, with steel spheres aiding the process. The boulders are then crushed further in an 8m, 16MW ball mill.