In the recent scenario with the continual increasing demand for cement with reduce
energy consumption; various suppliers are exploring a wide variety of cost-saving
manufacturing options. There are mainly three options available in industry i.e.
Vertical roller mill, Roller Press and Ball mill technology for finish grinding. The
selection parameters depend upon the physical properties of material being
ground, power consumption, throughput, space availability, maintenance aspects
and available hours.
A brief description of above options is given below.
7.1 Vertical Roller Mill (VRM)
For the finish grinding need, cements plants are presently going in for vertical roller
mill technology. Vertical roller mills present a compact and efficient grinding method.
Raw materials are ground on a rotating table that passes under large rollers. Material
is forced off the table by centrifugal force, where it is then swept up into an air
stream to a classifier immediately above. Material that is too coarse is returned to
the table for additional grinding while material that is fine enough is collected as
product. The compact design of a vertical roller mill allows it to dry, grind, and
classify, all within one piece of equipment and all in a relatively compact space.
The main features of Vertical roller mill are, power consumption savings; consistent
product quality and process simplification. The broad construction features of
VRM are as shown in Fig.1 below.
Lot of modifications has been done to improve the reliability and reduction in power
consumption over the years based on operating experience. Like, the segmented
and adjustable nozzle rings, introduction of external recirculation system, etc.