Trunnion overflow mill

Tumbling mills (a) trunnion overflow mill, (b) compartment mill, and (c) conical mill. 

FIGURE 6.16 Ball and rod mill discharge methods (a) trunnion overflow, (b) grate discharge, and (c) peripheral discharge. (From Meyers, R.A., Ed., Coal Handbook, Marcel Dekker, New York, 1981, p. 197.)... 

Tumbling mills are cylindrical size reduction devices and are essentially lined drums supported by hollow trunnions at each end. The units are manufactured with overflow, grate, or peripheral, discharge arrangements (Figure 6.16). 

---