Cement manufacturing process

1.What is cement ?
2.History.
3.Overveiw of Cement
Manufacturing process.
4.Overveiw of Kiln process.
5.Why burn wastes ?

Portland Cement
. A hydraulic cement made by finely
powderising the clinker produced by
calcining to incipient fusion a
mixture of argillaceous and
calcareous materials.
.Portland cement is a powder that is the
active ingredient in concrete.

Concrete
It is prepared by:-
. Shovel powder…………Portland Cement
. Shovels sand…………Mineral Aggregate
. Shovels Rock………. Mineral Aggregate
. Add water & mix.
. It is ready to mend .

Concrete
• Mixture of ingredients into a paste &
triggers a chemical reaction – hydration.
• Reaction forms a gel which coats & fills
spaces between the stone/sand;
• Hardens into a solid mass that
gets stronger & stronger.

Concrete
• The world’s most widely used building
material.
• Global production is 5 billion cubic yards
per year (using approximately 1.25 billion
tons of cement).

Concrete owes its strength and
durability to one essential ingredient -
Portland Cement.

Portland Cement
• Limestone + Shale/Clay + Heat = Clinker +
CKD + Exit Gas.
• Material Temperatures Exceed 2700 degrees F
• Pulverized Clinker + Gypsum = Portland
Cement.
• Cement is powder so fine that one pound
contains 150 billion grains.

Portland Cement (cont’d)
• Basic Chemical Components of Portland Cement:
– Calcium (Ca)
– Silicon (Si)
– Aluminum (Al)
– Iron (Fe)
• Typical Raw Materials:
– Limestone (CaCO3)
– Sand (SiO2)
– Shale, Clay (SiO2, Al2O3, Fe2O3)
– Iron Ore/Mill Scale (Fe2O3)

. Calcareous Component . Argillaceous Component
(providing Lime - CaO) (SiO2, Al2O3, and Fe2O3)
– limestone -clay
– marly limestone -shale
– chalk -calcareous marl
– coral limestone -marl
– marble -marly clay
– lime-sand -tuff, ash
– shell deposits - phyllite ,slate
– lime sludge -glass

• Clinker Chemistry
– Tricalcium silicate (3CaO.SiO2), (50-70%)
– Dicalcium silicate (2CaO.SiO2), (15-30%)
– Tricalcium aluminate (3CaO.Al2O3), (5-
10%)
– Tetracalcium aluminoferrite
(4CaO.Al2O3.Fe2O3), (5-15%)

SiO2
CaO CaO
CaO CaO
CaO CaO
Al2O3

History of Portland Cement
• First cements produced by early Greeks and
Romans from volcanic ash mixed with slaked lime.
• This art was lost during the Middle Ages.
• Portland cement developed in England by
bricklayer Joseph Aspdin in early 1800’s.
• Called “Portland” because concrete made with it
resembled natural stone from the Isle of Portland.

History of Portland Cement
• First rotary kiln designed to produce Portland
cement patented in 1885 by Frederick Ransome.
• First economical U.S. kilns developed by Atlas
Cement Company in 1895.
• Thomas A. Edison first developed long kilns (150
feet compared to 60 to 80 feet).

Types of Cement Processes
• Wet Process.
• Dry Process - 74% of cement produced.
• Preheater/Precalciner Process.

Evolution of the cement
Process
• Wet process easiest to control chemistry & better
for moist raw materials.
• Wet process high fuel requirements - fuel needed
to evaporate 30+% slurry water.
• Dry process kilns less fuel requirements
• Preheater/Precalciner further enhance fuel
efficiency & allow for high production rates.

Cement Kilns
• High temperature
• Long residence time
• Natural alkaline
environment
• CKD is only by-product of the process.
• Thermal stability

Kiln Process Control
• Critical Parameters: Fuel, Feed,
Kiln Speed, Gas Flow
• Kiln Temperatures - Burning Zone
• Kiln Stability
• Chemistry
• Instrumentation

Why Burn Wastes?
A cement kiln is a proven technology for
recycling by beneficial REUSE of solid and
hazardous wastes.
The benefits are:
– energy recovery
– material recovery
– economics
– environmental preservation

Federal State Established Priorities
for Industrial Waste Disposal
• Reduction at the source.
• Recycling
• Energy recovery
• Incineration
• Stabilization
• Landfill

Benefits of a recycling
Program
• Allows for reuse of waste materials.
• Conserves virgin fuels & raw materials.
• Regulated stringently for Environmental
Protection.

Waste Recycling Process
• Waste fuels are destroyed, releasing heat,
water and carbon dioxide.
• Solid materials are physically and
chemically combined in the clinker product.

Cement Kilns Excellent Environment
for Destroying &Recycling Wastes
A Cement Kiln Provides:
• 3,000degreeF + Flame
• Long retention times of gasses and
materials.
• Stability of a large dependable industrial
process.
• Many inherent safeguards.

A Cement Kiln Is A Proven
Technology For Beneficial REUSE of
Otherwise Waste Materials
The Benefits are:
• Energy Recovery
•Material Recovery

Recycling Programs
Energy Replacement for Coal/Coke.
• Liquid fuels.
• Solid fuels.
Material Replacement for Raw Materials
(Limestone, Shale and Sand).
• Solids/sludge slightly contaminated with metals.
• Solids/sludge slightly contaminated with
Organics.

THAT WAS A BREIF ON MAJOR
CEMENT INDUSTRY’S WORK.

Cement manufacturing process

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