Techno economically viable new energy efficient technologies for

cement industries

Dr. Kanagamani ThangavelChief Scientist

Corrosion Science & Engineering DivisionCSIR- Central Electrochemcial Research Institute, Karaikudi.

Types of cement

Ordinary Portland cement (OPC)

Portland pozzolana cement (PPC)

Portland slag cement (PSC)

White Portland cement (WPC)

Sulphate resistance cement (SRC)

Chemical composition of cements Wt%

Compound OPC PPC PSC

Silicon-di-oxide (SiO ) 20–21 28–32 26–30Silicon-di-oxide (SiO2) 20–21 28–32 26–30

Aluminium oxide (Al2O3) 5.2–5.6 5.0–8.0 9.0–11.0

Ferric oxide ( Fe2O3) 4.4–4.8 4.9–6.0 2.5–3.0

Calcium oxide (CaO) 62–63 41–43 44–46

Magnesium oxide (MgO) 0.5–0.7 1.0–2.0 3.5–4.0

Sulphur-tri-oxide (SO3) 2.4–2.8 2.4–2.8 2.4–2.8

Loss on ignition (LOI) 1.5–2.5 3.0–3.5 1.5–2.5

ASTM C150 / C150M - 12 specify the Standard Specification for Portland Cement

Cement production – 1.0 ton- 1.5 tons earth minerals- 1.0 ton of CO2

CaCO3 ---------------���� CaO + CO2

Global warming

3 2

Calcium Calcium Carbon

carbonate oxide -di-oxide

The greenhouse gas effect leads to the ozone layer depletion and global warming.

Cement manufacturing process

Cement Production Processes Raw materials preparation

� Primary and secondary crushing of quarry materials

� Drying the materials � Grinding through either wet or dry process � Energy consumption <5%

Clinker production Clinker production � Energy intensive step� Energy consumption 80%� Wet or dry process

Finish Grinding � Mixed with additives� (Gypsum, anhydrite, pozzolona, fly ash, blast

furnace slag)

Cement Production in India

India – Second largest producers of cement

2003 - 115 million metric tons

Average annual growth rate 8% (1981 – 2003)

2020 - 425 million metric tons 2020 - 425 million metric tons

Energy consumption – Primary energy 1100 to 1700 PJ

-- Final energy 1500 to 2100 PJ

List of Popular Cement Plants in India

� India Cement

� JK Cement Limited

� Jaypee Group

� Century Cement

� L & T Cement � L & T Cement

� ACC Limited

� CCI Cement Plants

� Gujarat Ambuja Cement Plants

700000

800000

900000

1000000

1100000

1200000

1300000

1400000

Statistical comparison of cement production in India

from 1991 to 2008 - Line ChartC

em

en

t P

rod

uc

tio

n

Thousand Tons

A B C D E F G H I J K L M N O P Q R0

100000

200000

300000

400000

500000

600000

080706050403020100999897969594939291

Ce

me

nt

Pro

du

cti

on

Year

Average and best practice energy consumption values for Indian cement plants by process

Top Contributor States in Cement Production

States No. of cement plants Production million

tons

Madhyapradesh 19 26.23

Andrapradesh 20 17.00

Rajasthan 16 35.79

Gujarat 12

Tamilnadu 10

Countries

Export quality Bangaledesh

Nepal

Sri Lanka

Myanmar

UAE

Singapore

Cement industry energy consumption

Year Cement

production

(million metric

tons)

Energy consumption

Primary

energy

PJ

Final energy

PJ

1992 58 261 195

2002 110 466 352

NCCBM : National Council for Cement and Building Materials

Energy Consumption - 25 to 30%

Savings upto - 164 k.cal/kg of clinker

16.4 kWh/ton of cement

Potential cost savings - 4.40 million to 66.20 million annually

Energy Efficient Equipment

Slip power recovery system

Variable voltage and frequency drives

Grid rotor resistance

High efficiency separator

High efficiency grate coolers

Energy Efficient Management and process

control optimization

Plugging of leakages in Kiln and pre-heater circuitPlugging of leakages in Kiln and pre-heater circuit

Raw mill and coal mill circuits

Installation of improved insulating bricks

Effective utilization of hot exit gases

Optimization of Kiln operation

4.8 to 4.2 GJ/t (P.E)

3.6 to 3.1 GJ/t (F.E)

Utilization of waste heat – Generation of electricity

3 to 5.5 MW in 20 surveyed cement plants

200 MW - 45 plants (1 million tons per year)

Alternate and waste fuels – lignite, pet coke, tyres, rice husk,

groundnut shell,

Energy efficient technologies

• Alternate materials for cement

• Activated fly ash cements

• Use of composite cements – binary / ternary • Use of composite cements – binary / ternary

Cements

• Production of nano silica from rice husk ash

Blended cements are produced by the addition ofsupplementary cementitious materials:

Blended cements : Supplementary cementitious materials

S.No Supplementary materials Source industry

1 Fly ash Thermal power station

2 Rice husk ash Rice Industries

3 Blast Furnace slag Iron and steel

IndustriesIndustries

4 Silica fume Ferro silicon industries

5 Bagasse ash Sugar industries

6 Metakaolin Natural clay material

These supplementary cementitious materials possess properties which impart

certain desirable characteristics to the concrete mix which can enhance the

strength and durability of concrete structures

No of thermal power stations in India : approx. 72

Fly ash production in India : 100 – 150 million tons/ year

Fly ash utilization in India : 2 million tons per year

Statistical data on Fly ash

Advantages :

� Larger savings in cement

� Reduced heat of hydration

� Greater durability

� Activation of fly ash : to improve the reactivity

Physical activation

Thermal activation

Blended cements

Thermal activation

Chemical activation

n =2n > 3

OPC

ACTIVATED FLY ASH

Activation Mechanism

Cement

Fly ash

n =1FLY ASH

MECHANISM OF ACTION BY CHEMICALLY ACTIVATED FLY ASHNeutralization of surface silanol group

Si OH + NaOH = Si ONa + H2O ------ (1)

The solubility of Na+ is more than that of Ca2+

This neutralisation repeats on new surfaces, known as corrosion of fly ash.

Gradual destroying of inside silane chain, resulting in [(Si,Al)O4]n disintegration

Si O Si + 2NaOH = 2( Si ONa) + H2O ------ (2)

Si ONa is replaced by Ca2+ , forming sedimentary calcium silicate hydrate.Si ONa is replaced by Ca2+ , forming sedimentary calcium silicate hydrate.

Si ONa + Ca2+ = Si O Ca + Na+

or (CSH) ------- (3)

2( Si ONa)+ Ca2+ = 2( Si O Ca) + Na+

or (CSH) ------ (4)

Repeating the above reactions, it can accelerate fly ash activation.

Parameters RHA BA

Production in India /

year

35 million tons 300 million tons

Quantity of ash

produced / 1000 kg

200 kg 150 kg

SiO2 content 93% (87%) 73 % (64%)

Carbon content for

processed ash

2.1% 4.9%

Critical parameters for processed RHA and BA

processed ash

Grain size 3.8 microns 5.4 microns

Specific surface area 36.47 m2/gm 10.50 m2/gm

Improved properties for 30% RHA and 20% BA

Water permeability 35% reduction 40% reduction

Sorptivity 45% reduction 20% reduction

Chloride diffusion 30% reduction 50% reduction

Chloride permeability 75% reduction 55% reduction

OPC

OPC+PPC

50%

50%

PPC OPC+PSCOPC+PPC

50%

50%

25%

Flow chart for preparation of Binary & Ternary Cements

PSC

PPC

PPC+PSC

OPC+PSCOPC+PPC+PSC

50%

50%

50%

25%

�All the cements are commercially available

�Ternary system showed improvedmechanical properties and betterprotection for steel in concrete.

Binary and Ternary cements

protection for steel in concrete.

�Ternary cements are not cost effective buteffectively durable

Synthesis and Properties on

nano silica concrete• NS – RHA – Precipitation method

� Mechanical Properties…..

� Physical properties……

� Corrosion resistant properties…..

� Ten grams of RHA samples were stirred in 80 ml

distilled 2.0, 2.5 and 3.0 N sodium hydroxide solution,

respectively.

� RHA was boiled in a covered 250 ml Erlenmeyer

flask for 3 h.

� The solution was filtered and the residue was

Synthesis of pure silica from rice husk ash

� The solution was filtered and the residue was

washed with 20 ml boiling water.

� The filtrate was allowed to cool down to room

temperature and added 5 N H2SO4 until pH 2 and

then added NH4OH until pH 8.5 allowed to room

temperature for 3.5 h.

� The filtrate was then dried at 120oC for 12 h.

� Pure silica was extracted by refluxing with 6 N HCI for

4 h and then washed repeatedly using deionised water

to make it acid free.

� It was then dissolved in 2, 2.5 and 3.0 N NaOH by

continuous stirring for 10 h on a magnetic stirrer and

then concentrated H SO was added to adjust pH in

Preparation of nanosilica

then concentrated H2SO4 was added to adjust pH in

the range of 7.5-8.5.

� The precipitated silica was washed repeatedly with

warm deionised water until the filtrate became

completely alkali free.

� The washing process continued by deionised water

repeatedly and dried at 50oC for 48 h in the oven.

SEM micrograph for Nano

silica

40

45

50

55

60

65C

om

pre

ssiv

e S

tren

gth

, M

Pa

3 days

7 days

14 days

28 days

Compressive strength of NS cement mortar

Mix design : 1:2.75

w/c ratio : 0.52

Size : 50 x 50 x 50 mm

0.0 0.5 1.0 1.50

5

10

15

20

25

30

35

Co

mp

ressiv

e S

tren

gth

, M

Pa

% of Nano Silica

SYSTEM Strength (N/mm2)

3 days 7 days 14 days 28 days

Split Tensile Strength of NS admixed

cylinders (ASTM C496-90)

Mix design : 1:2.75

w/c ratio : 0.52

Size : 60 mm dia. x 100 mm height

3 days 7 days 14 days 28 days

CONTROL 1.908 2.76 2.76 2.76

NS1 (0.5 % NS) 1.908 2.97 2.97 2.97

NS2 (1.0 % NS) 2.12 2.97 3.18 3.18

NS3 (1.5 % NS) 1.802 2.97 2.97 2.97

Synthesis of nano silicaNano silica is synthesized from Rice Husk Ash(RHA- an industrial waste) by precipitation method.

Nano Silica

Compressive strength (N/mm2)

Compressive strength of NS cement mortar

SYSTEM 3Days 7 days 14 days 28 days

CONTROL 9 10.8 13.6 24.9

NS1(0.5%NS) 13.2 15.6 21.2 45.3

NS2(1.0%NS) 18.3 20.4 24 61.6

NS3(1.5%NS) 20.1 22.0 23.2 40.8

� The compressive strength of mortar is increased by 2.5 times

after 28 days of curing at 1% NS level. More over irrespective of theperiod of curing (3, 7 and 14 days) the compressive strength ofmortar actually doubled at 1.0% NS level.

� The split tensile strength of mortars showed a marginal increaseat 1.0% NS level.

Nano Silica

� The bulk and apparent density of cement mortars also showed amarginal increase at 0.5%, 1.0% and 1.5 % NS levels.

� Sorptivity results indicated that a considerable decrease (50%)observed at 1.0% NS level when compared to 0.5% NS level.

� RCPT test results showed that a considerable decrease in chargepassed (6%, 8% and 15% for 0.5%, 1% and 1.5 % NS levelrespectively).

Conclusions

� Cement task force

� Energy Audits

� Identification of best practices – cogeneration of

electricity from waste heat

� Increased promotion of blended cements

� Effective utilization of above energy efficient

materials will enhance the economical growth of

our country.

CECRI is there

Not for the PRODUCTION of bridgesBut for the PROTECTION of bridges

Not for the inspection of BARS in hotelsBut for the inspection of REBARS in bridges

Not for the DISINTEGRATION of materials But for the INTEGRATION of National Assets

Not for the DOWNFALL of structures But for the UPLIFTMENT of economy

When we build, let us think that

We build for ever

Let it not be, for the present delight

Nor for the present use aloneNor for the present use alone

Let it be such work as our

descendants will thank us for