CEMENT MANUFACTURING PART (1)

A BRIEF DESCRIPTION OF CEMENT MANUFACTURING
PROCESS

Hi friends I thought to share my knowledge about cement process with you
since i work in the industry for the last one year.The work in cement
field is challenging and stimulating.You have to be a process man,you
must know something about mechanical equipments like Fans,Weigh
feeders,Bucket Elevators,You should have minimum working knowledge of
electronics also because in cement industry we use a wide array of
sensors and sophisticated equipments for measuring various process
parameters like temperature,pressure,flow rate etc...,also you should
possess good interpersonal skills and should be a manager to coordinate
and to extract work from others which matters a lot.
Cement is a low value but high volume product requiring huge investments
with long term payback periods requiring careful maintenance of assets
at regular planned intervals.

Definition of Cement:-

Cement is a hydraulic binder which means it forms a semi solid paste
when mixed with water which progressively gains strength under water in
due course of time.

Raw materials:-

The main raw materials used in the manufacture of cement
are(1)Calcareous materials like Limestone,Shale etc.. which contains
Calcium Carbonate in them as a major component,and (2)Argillaceous
materials like clay which provide oxides of Iron and Aluminium.

Various stages in cement manufacturing process

(A)Raw material extraction stage:-The main raw material being limestone
is quarried from limestone quarries and hauled to the crusher using
trucks or belt conveyors to a crusher for size reduction.The limestone
quarry is open cast type in contrast with coal quarry which is
underground.The quarry for limestone is divided into various benches
from which limestone is extracted by drilling,blasting with explosives
and eventual hauling to the cement plant.Limestone accounts for almost
70-90% of raw mix.
The other raw material is clay which is extracted from clay quarries
near the cement plants-in some cases the clay requires drying on account
of their high moisture content and stickiness.

(B)Limestone Crushing:- The quarried limestone must be amenable to
cement manufacturing process,so we must crush the limestone to suitable
size to feed it to the cement process for subsequent processing.The
various types of crushers used in cement industry are Hammer
crusher,Impact crusher,Jaw crusher,Gyratory crusher etc....All these
differ only in the mechanism which they employ for size reduction of
limestone-impact,shear etc...

( C )Preblending:-The limestone originating from different benches in
the limestone quarry is of different quality and therefore must be
preblended using a stacker reclaimer to get uniform quality of feed.

(D)Raw material Grinding:-At this stage the raw materials-Limestone,Clay
and additives are fed to the Raw Mill-which can be either a Ball Mill or
a Vertical Roller Mill(VRM)-Mainly impact & shear forces are utilized in
these equipments to effect size reduction.The ground material is
collected with the help of dedusting equipments like Electro Static
Precipitators(ESP) and Bag Filters.