Over the last few decades, the air-swept vertical roller mill has become the standard solution for coal grinding installations. The ATOX grinds and dries all types of coal and is highly economical in terms of speciﬁc energy consumption. The ATOX coal mill is suited for various installation types, whether inert or non-inert and direct or indirect ﬁring systems. An inert system designed for indirect ﬁring is the most common solution at cement plants.
basic structure components of coal mill
1. Main gear unit
2. Hydraulic cylinder, incl. accumulators
3. Tension rod
4. Grinding table
5. Buffer house for torque rod
6. Grinding roller assembly
7. Double feed screw
8. Reject cone
9. Guide vanes
10. Cage rotor
11. Mill outlet
12. Variable speed drive for separator
Working principle of coal mill plant
The raw coal enters the mill via an airtight feed screw and is discharged onto the centre of the rotating grinding table. The rotation of the table accelerates the ﬂow of material towards the grinding track where the coal is ground between the table and the three rollers. The coal then continues over the dam ring and is entrained in the hot drying air that enters the mill house through the nozzle ring. The air lifts the coarser particles back onto the grinding table and sweeps the ﬁner particles up to the separator that lets the ﬁnal product proceed to the mill outlet while returning the coarse fraction to the table for further grinding. Having left the mill at the top, the ﬁnal product continues with the air to a cyclone or a bag ﬁlter where it is collected.