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Lean and
Clean
Manufacturing
Module 8
Cement Manufacture
June 4th 2013
Malolos City
Alma Politano
BULSU 1
Philippines Cement Industry
According to study, the country’s cement
industry is getting a major boost from the
robust expansion of the construction
sector
State planners are looking at between
6.6% and 7.6% economic growth this year,
2012 and by 7.4% and 8.6% in 2014, with
industry, including construction, leading
the growth
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According to the Cement
Manufacturers Association (CeMAP),
demand for cement rose by 18% in
2012, the steepest in 15 years.
San Miguel purchased a 25% stake in Northern Cement, the company
intends to spend US$750m on the
construction of three cement plants
(2013 -2015).
Holcim and Lafarge plan to expand
their facilities in Norzagaray, Bulacan
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What is cement ?
A powder so fine that one pound
contains 150 billion grains
Cement is a binder, a substance that
sets and hardens independently, and
can bind other materials together.
Heated at Temperatures above
2700˚F (1480˚C) to form clinker
Pulverized Clinker + Gypsum =
Portland Cement
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High temperature, long retention times and
complete combustion are strengths of this
process. The continuous process and strict,
highly technical control ensures their
conversion into a new product.
This is vital to produce cement clinker with a
mineralogical structure that is highly reactive
with water.
Changing the chemical composition of the
raw mix enables cements with different
properties produced for different uses.
SIMPLE? BUT 8
Portland cement
TYPICAL RAW MATERIALS:
Limestone (CaCO3)
Sand (SiO2)
Shale, Clay (SiO2, Al2O3, Fe2O3)
Iron Ore/Mill Scale (Fe2O3)
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Essential in building materials
Cement mixed with water, sand
and gravel, forms concrete.
Cement mixed with water and
sand, forms cement plaster.
Cement mixed with water, lime
and sand, forms mortar.
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Simple process description
Cement is made from a mixture of materials
containing calcium, silica, aluminum and
iron.
A high-temperature kiln heats the raw
materials, transforming them chemically
and physically into clinker. This gray
pebble-like material (mainly calcium
silicate) gives cement its binding properties.
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Cement Kiln is the heart of cement production
process: its capacity usually defines the
capacity of the cement plant.
Hot end of medium sized modern cement kiln,
showing tires, rollers and drive gear
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Clinker - lumps or nodules, usually 3–25 mm in diameter formed by
heating the raw materials in a rotating kiln.
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Clinker is then mixed with gypsum
and ground to a fine powder to make
cement
Gypsum is a mineral and hydrated
calcium sulfate, which is added to
control the “setting of cement”
It controls the rate of hardening the
cement
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Different methods of mixing
Black mixing: raw materials i.e. lime
stone, clay, iron ore, additives ground
together with coal.
Grey mixing: half of ground coal
mixed with the materials and the
other half (size <3mm) mixed in the
ball forming process.
White mixing: coal and raw materials
are ground separately and are mixed
in the ball forming process.
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1.) Limestone is taken from a quarry.
Smaller quantities of sand and clay
are also needed. Limestone, sand
and clay contain the four essential
elements required to make cement -
calcium, silicon, aluminum and iron.
2.) Boulder-size limestone rocks are
transported from the quarry to the
cement plant and fed into a crusher
which crushes the boulders into
marble-size pieces.
3.) The limestone pieces then go
through a blender where they are
added to the other raw materials in
the right proportion.
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4.) The raw materials are ground to a
powder. This is sometimes done with rollers
that crush the materials against a rotating
platform.
5.) Everything then goes into a huge,
extremely hot, rotating furnace to
undergo a process called "sintering“, a
coherent mass formed without melting,
just partially molten. The raw materials
reach about 2700° F (1480°C) inside the
furnace. This causes chemical and
physical changes ; they come out of the
furnace as large, glassy, red-hot cinders
called "clinker". Materials fed into the
process become part of the clinker
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The cement is then stored in silos (large
holding tanks) where it awaits
distribution.
6.) The clinker is cooled and ground into
a fine gray powder. A small amount of
gypsum is also added during the final
grinding. It is now the finished product -
Portland cement. Cement can also be
blended with supplementary
cementitious materials (SCMs), such as
flyash and slag, to make blended
cements.
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Major environmental concerns Facilities with new technologies - The
combustion of fuels, and the conversion of limestone to clinker releases emissions such as CO2, metals, oxides of nitrogen (NOx) and dust.
Facilities with older technologies : airborne pollutants
mainly SO2 and NO2 from the kiln
Dust and particulates from a number of solid processing and handling operations
trace micro-size materials from combustion of fuels and feedstock. metals, e.g. vanadium from fuel oil, dioxins,
furans, and PAHs (polycyclic aromatic hydrocarbons)
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Environmental concerns Raw materials
Environmental issues arising from the
handling of raw materials, include dust and
stormwater runoff, CP alternatives - use of
waste products as an alternative to natural
raw materials.
To conserve natural resources and reduce
CO2 emissions, alternative fuels such as
waste tires, timber, oils and other materials
are used.
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Fig. 1. Process flow diagram for the cement manufacturing
process with inputs and outputs
(Huntzinger and Eatmon, 2009).
Additionally
Cement grinding
Mineral additions and SCMs are added
to reduce the amount of clinker in
cement.
This reduces the fuel, power, process
emissions and raw materials.
It creates a use for material
considered to be a waste product of
other industries.
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CP Changes to be Implemented
Apply Cleaner Production and Circular
Economy principles to deal the problems
of solid waste. In China cement industries
have carried out CP practice to different
levels at different plants resulting to the
reduction of coal consumption and the
protection of the environment.
Apply advanced control technology and
improve equipment design (e.g. bag filter
facilities) to reduce gas emissions.
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CP Actions Implemented
Recycling of powdered dust by using
different types of improved dust collection
equipment. This process reduced air
pollution and increased energy/ resource
savings.
Comprehensive reutilization of cement
wastes
Strict implementation of CP –Cement plant
must employ the best available technology
and required equipment for pollution control
and prevention
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CP Actions Implemented
Alternative and substituted materials such
as fly ash from power plants, steel mill
slugs, and pozzolanic substances can be
used in cement to replace some of the
limestone which is the main raw material,
and the quality of the product is not
affected in the applications.
Apply environmental impact assessment
(EIA) and social impact assessment for all
new cement projects.
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Why do we need to
apply CP principles
in industries?
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