Rod mill crushers use long rods for grinding media, the rods grind the ore
by tumbling within the mill. Rod mills are most useful when a very coarse product is required, and/or overgrinding must be minimized. Rod mill crushers are often employed to grind the material to a size then suitable for ball mill
crushers. The other types of crushers include: jaw crusher
, ball mill
crusher, hammermill crusher
, gyratory crusher, and roller crusher.
There are three types of rod mills; overflow
, end peripheral discharge
, and center peripheral discharge
. The most common being the overflow mill. In the mineral processing industry the wet grinding rod mill
is normally used, dry grinding rod mill
s are much less commonly used. The length, diameter, and capacity of rod mills are limited by the maximum rod length of about 20 feet. The rods must stay parallell
to each other because if they become misaligned much of the grinding action is lost and rod tangling may occur.
The peripheral speed
of the inside of the mill determines the mills operationg speed. They usually operate from 280 fpm (feet per minute) to 480 fpm at the periphery. Rod mills are normally run at low speeds usually less than 70% of it's critical speed
. The rod mill is suitable for avoiding overgrinding, while the ball mill
is suitable for fine or super fine grinding.