Lean and

Clean

Manufacturing

Module 8

Cement Manufacture

June 4th 2013

Malolos City

Alma Politano

BULSU 1

Holcim and Lafarge Cements

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Eagle Cement ,

San Ildefonso, Bulacan

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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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Quarrying Site in Bulacan

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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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CEMEX, nd 21

QUARRYING CRUSHER

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GRINDING & BLENDING OF

RAW MATERIALS

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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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Benhelal et al, 2012 28

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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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Bag Filter – used to allow no

loss of raw materials

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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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MOTHER EARTH CAN NO LONGER WAIT.

We need to ACT NOW!!!

THANK YOU FOR

LISTENING!

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