csir
TRANSCRIPT
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