MILLING PROCESS:
Milling process is also called as ‘screening’ and ‘sizing’ process. Milling is employed between RMG and Blending to crush the larger particles from granulation into uniform small particles which meets the process requirement.
Milling isperformed to remove lumps, improve flow, reduce segregation and to control the particle size.
Milling is performed by using the equipment like Multi mill, co-mill, oscillating granulator, sizer mill, etc.
OPERATING PRINCIPLE OF A MILLER:
A miller consists of impeller and knives (blades) in which a rotating mill, the shape, and orientation of the impeller blades produce a finely granulated powder of desired specification.
PARTS OF MILLER:
- Impeller
- Knives
- Sieve / Screen
- Motor
- Vessel
The Impeller rotates within an annular array of knives and the product is fed into the center area of the impeller.
Centrifugal force moves the product across the rotating impeller and into contact with the impeller blades and the knife array.
The impeller has a generally circular impeller body / vessel that is rotatable about a generally centrally located rotational axis and a plurality of impeller blades attached to the impeller body.
The sieve / screen separates the fines particles from the coarse particles which are once again fed into the miller.
PROCESS VARIABLES IN MILLING:
- Speed of the impeller
- Type of sieve / screen
COMPARISON OF THE CO-MILL AND THE MULTI MILL:
