CEMENT MANUFACTURING PROCESS PART (2)

(E)Raw Meal Homogenisation:-After the raw meal powder is collected in dedusting devices they are send to Homogenising Silos(Pneumatic) for better homogenization inorder to produce a uniform kiln feed to avoid process problems.

(F)Pyroprocessing Section:- The homogenized raw meal is then fed into a Suspension Preheater with Precalciner arrangement where they undergo complete dehydration and partial decarbonation(upto 96%) in contact with the hot flue gases originating from the combustion process of fuels(coal,animal meal,plastics etc...) inside the kiln.The flow of material and gas are counter current with respect to each other.The various stages of Preheater tower are called cyclones which are connected by ducts.This partially calcined raw meal enters the kiln which is the heart of the cement manufacturing process and then in the burning zone the material becomes semi liquid and formation of clinker starts at temperatures of 1300-1400°C. The clinker so formed then falls into the clinker cooler where the clinker undergoes sudden cooling(quenching).This sudden cooling of clinker helps to arrest the clinker phases,helps in valuable heat recuperation back into the kiln,avoid formation of large periclase(MgO) crystals which are detrimental to clinker strength.
The various clinker phases are C3S,C2S,C3A & C4AF which are known as Alite,Belite,Aluminate and Ferrite respectively.Alite give early strength,Belite later strength,Aluminate hydration properties and Ferrite provides the colour.The average thermal consumption for the cement manufacturing process with Suspension Preheater and precalciner is about 650-750Kcal/Kg.Clinker.

(G)Clinker Storage and Cement Grinding stage:-The clinker so formed is transported to either clinker silos or a clinker storage shed where the clinker is stored for about 1-2 weeks prior to grinding-this process is called seasoning of clinker and gives better results with respect to cement properties.
The seasoned clinker which has a size of about 1.5-3 cm is transported to Cement mills(horizontal/VRM) where they are ground along with gypsum(set retarder),slag and flyash for making different varieties of cement.The ground cement size is expressed as residue on 90 and 212 micron sieves.

(H)Cement Packing and Despatch Section:-This is the last stage of the cement manufacturing process.The cement powder from the cement mills is collected in dedusting devices like ESP and Bag Filters and then transported to cement silos to be send as bulk cement or send to cement packers to be sold as cement packets.

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.

THE BIRTH OF THE BHAGAVAD GITA

The Battle of Kurukshetra began on the day known as Moksada Ekadasi. On
that day, Krishna enlightened Arjuna with the knowledge of Bhagavad-gita
liberating him. Each year this day is celebrated as Gita Jayanti.

The first verse of the Gita refers to Kurukshetra as dharma-kshetra, or
the field of dharma, indicating that it was already known as a holy
place.Today one can find many ancient temples and sacred lakes at
Kurukshetra, an area of about one hundred square miles between the
sacred rivers Saraswati and Drshadvati in Haryana state.

Kurukshetra was formerly known as Brahmaksetra, Brghuksetra, Aryavarta
and Samanta Pancaka. It became known as Kuruksetra because of the work
of King Kuru. He went there on a golden chariot and used the chariot's
gold to make a plow. He then borrowed Lord Siva's bull and Yamaraj's
buffalo and started ploughing. When Indra arrived and asked what he was
doing, he replied that he was preparing the land to grow the eight
religious virtues : truth, yoga, kindness, purity, charity,forgiveness,
austerity and celibacy.

Indra granted King Kuru a boon that anyone who died there while fighting
or doing penance would be admitted to heaven.

It is at Jyotisar ( five miles from the town of Kuruksetra ) where Lord
Krishna spoke the Gita. The exact spot is marked by a marble chariot
under a banyan tree that is said to to be over five thousand years old.

It is at Kuruksetra that Lord Krishna was reunited with the residents of
Vrindavan after a long period of separation.The loving exchange between
Krishna and the gopis at Kuruksetra is the esoteric meaning behind the
festival known as the Rathayatra. So whenever Hare Krishna devotees put
on rathayatras in cities around the world, they are celebrating the
glories of Kuruksetra.

KURUKSETRA'S HOLY SITES

Brahma Sarovar:

Lord Brahma is said to have created the earth here.During solar
eclipses, pilgrims come to take a dip in the Brahma Sarovar, the largest
lake here, observing an ancient tradition.

Samanta Pancaka :

Kuruksetra is known as Samanta Pancaka ( five lakes ) because Lord
Parasurama made five lakes from the blood of the ksatriyas He killed.

Baan Ganga or Bhishma Kunda :

This is where Arjuna shot an arrow into the earth and produced Ganges
water that gushed out like a fountain to quench the thirst of Bhishmadev
as he lay dying on the bed of arrows. This place is three miles from
Kuruksetra.

There is a second Baan Ganga where Arjuna shot an arrow and produced
drinking water for his chariot horses during his single combat with
Jayadratha.

Karnavadha :

A long trench where the wheels of Karna's chariot were stuck before
Arjuna killed him.

Chakravyuha :

It is here that Dronacarya arranged his army in the form of a cakra or
discus. Abhimanyu, son of Arjuna and Subhadra got into this formation
but couldnot get out and was subsequently killed.

SRILA PRABHUPAD AT KURUKSETRA

Sumati Morarjee who in 1965 gave Srila Prabhupada a free passage on her
steamship the Jaladuta remembers meeting him here for the first time in
the 1950s. Srila Prabhupad was sitting under a tree in Kuruksetra,
chanting on his beads. Sensing that he was a distinguished sadhu, she
approached him.She was impressed with his humility and devotion and she
mentioned this to him when he went to her for help to get to America.

In 1970, he passed through Kuruksetra on the way to Amritsar. In 1975 he
went to Kuruksetra with several disciples.He visited Jyotisar and
inspected the place carefully.

In 1996, Prabhupad's Centennial year, devotees purchased a parcel of
land in Jyotisar.At present ISKCON runs a small temple in Thaneswar, a
couple of miles from Brahma Sarovar. Devotees are planning, designing,
and raising funds for the complex Srila Prabhupad wanted in Jyotisar.
In 1996 itself, a prominent square in the town of Kuruksetra was named
after him : Bhaktivedanta Swami Chowk.

HOW TO GET THERE, WHERE TO STAY

Kuruksetra is a four hour train ride from Delhi.There are also direct
trains from Mumbai, Agra, Baroda,Chandigarh and Simla.

There are several inexpensive dharamsalas there. The best hotel in town
is the Neelkanthi Krishna Dham Yatri Niwas. In Jyotisar you can try the
secluded Canal Guest House.

( Material for this article was taken from BTG, March 2004 , Indian
edition.)

........................................................................
.

DESIRE IS THE STARTING POINT FOR SUCCESS

Dear Friends,

The first thing that will contribute to reaching your goal
is that you simply want to reach it badly enough.
You must learn how to desire with sufficient intensity to be successful.

If you have the desire you have the power to attain success.
You can really have anything you want in life if you go after it.
But you have to want it.

As a drowning soul desires air,
as a shipwrecked person craves fresh water,
so must you feel that intense, eager, insistent, demanding,
ravenous desire for your success.

Your desire for success must be so strong within you
that it becomes the very breath of your life.
It must be your first thought when you wake up,
and your last thought when you go to bed at night.

You can have anything you want if you go after it with intensity.

Bravo!!

DESIRE IS THE STARTING POINT FOR SUCCESS

Dear Friends,

The first thing that will contribute to reaching your goal
is that you simply want to reach it badly enough.
You must learn how to desire with sufficient intensity to be successful.

If you have the desire you have the power to attain success.
You can really have anything you want in life if you go after it.
But you have to want it.

As a drowning soul desires air,
as a shipwrecked person craves fresh water,
so must you feel that intense, eager, insistent, demanding,
ravenous desire for your success.

Your desire for success must be so strong within you
that it becomes the very breath of your life.
It must be your first thought when you wake up,
and your last thought when you go to bed at night.

You can have anything you want if you go after it with intensity.