News Latter VOL_3.indd - SECAR®, solutions for refractories

No.3 | July 2012
Kerneos Research and Technology Centre (KRTC), Lyon, France
Kerneos India Application Lab (KIAL),Kolkata,India
Calcium aluminate cement is a key component
for both conventional as well as low cement
castables. To ensure consistent placing properties
of castables, it is essential to use a cement of
reliable quality, which can develop regular placing
and hardening properties in castable. New
cements with adapted functionalities offer better
optimisation of the usage qualities of castables.
(Full Paper on Page 3)
Dear Friends,
I am indeed pleased to greet you through this third edition of Secar ® GAZETTE. It’s just
a couple of months since I have taken over the reins of Kerneos India & Middle East
Operations from my predecessor, Jean-Christophe Trassard. I had spent almost two
decades earlier in the refractory industry but this is a new role as a key supplier to the
refractory and construction industries. I look forward to renewing my old association
with friends in the industry as well as nurture new partnerships and associations.
Economists predict that until at least the middle of the next decade, global growth
is likely to slow to approximately 3 percent per year on average – a rate somewhat
below the average of the last two decades. When such a gloomy picture is painted,
what can industries do to sustain business? I can think of only one answer and that’s innovation…innovation in
everything we do.
At Kerneos, innovation is placed very high in our scheme of activities, well acknowledging that it is the key to drive
economic recovery in the short term and ensuring prosperity in the long term. Amongst the many initiatives Kerneos
has taken on a global scale to share innovative ideas and solutions with customers, we have organized a one day
regional workshop at Visakhapatnam in association with the Visakhapatnam chapter of the Indian Ceramic Society
on 9th August 2012 on “Improving Castable Refractories with Calcium Aluminate Cements”. I strongly encourage
key technical hands in the refractory industry to attend the workshop and benefit from the interactive proceedings.
This issue of Secar ® GAZETTE brings you an interesting article on “Role of calcium aluminate cements to optimize
castable placing and hardening”. Also, there are some tips and news, all designed to quench your thirst for useful
technical and industry information. We would appreciate your feedback and inputs that would help us further
improve the contents in the forthcoming editions.
Wish you happy reading!
Segi P. Idicula Managing Director Kerneos India & Middle East Operations

Market Pulse
Tough Times Ahead for the Sponge Iron
Industry
The Sponge Iron industry is facing an
acute shortage of its key raw material –
iron ore.Coupled with this the stringent
government policies and recession in
the user steel industry are making for a
bleak future for the industry in India.
Concerns over environmental pollution,
tough government policies as coal-based
processes are highly energy intensive are
other crucial factors accountable for the
downslide. The global economic crisis is
no less a contributor.
The installed capacity of sponge iron in
India is 35 millon tonnes while production
is around 26 million tonnes. There are
two process routes for manufacture, viz.
through gas or non-coking coal. About
45 per cent of the capacity is gas-based.
The industry is made up of 300 small units
and 10-15 large producers. Essar Steel,
Jindal Steel and Power, JSW Ispat and
Tata Sponge are the top four producers
in India. The present crisis has led to an
outage of capacity to the tune of 10%
to 15%. India is the largest producer of
sponge iron for the last nine consecutive
years contributing to the economy in
terms of taxes and employment. In the
future too, sponge iron will continue to
play an important role in steel making
domestically.
Natural gas has a limited availability
in India, the price is regulated by the
government and allocation is also
restricted to each of the using sectors.
The government is not able to meet the
gas requirements of power companies,
and sponge iron companies are low in
priority. Hence, the tilt is towards coalbased
plants for sponge iron companies.
Proposed New National Steel Policy
The new policy is likely to be finalised
in about a couple of months, the Steel
Secretary, Mr D.R.S. Chaudhary, told
Steel Summit 2012, organised by the
Confederation of Indian Industry. It would
replace the National Steel Policy 2005.
“The new policy will focus on removing
infrastructure bottlenecks, improving
technology and will focus on achieving a
10 per cent growth. That’s the only way
to grow. The more we expedite the new
policy, the more beneficial it will be,” Mr
Chaudhary said.
Currently, the Indian steel sector is
growing at a compounded growth of five
per cent. Steel production is around 72
million tonnes, broadly in line with the
domestic demand. However, the demand
is set to accelerate and touch 200 million
tonnes by 2020.
The Indian steel industry is at the cusp of a
sustained high-growth phase. While low
per capita consumption provides a huge
market potential, the industry is faced
with challenges such as resource scarcity,
delay in clearances and land acquisition
among others.
Tech Edge
SECAR®712 is a new generation 70% Al 2
O 3
cement and is the result of a novel process
developed by Kerneos. It possesses all the
attributes of SECAR®71 and more, a unique
scientific breakthrough: time stable properties!
As a result, SECAR ® 712 achieves new levels of
castable performance:
• Time stability counter balances a natural effect
called ageing and enables stable properties of
cement as well as castable over time. Stability
of working time (both cement and castable) is
observed even after 12 months storage.
• Very low moisture pick-up is obtained in
castables, especially beneficial in low cement
systems.
• Outstanding compressive strength stability (6
hours) is observed even after 12 months.
• SECAR ® 712’s shelf life is longer than 12
months and properties retained for 24 months
in simulated ageing.
• SECAR ® 712 offers the same versatility
as SECAR ® 71 and can be used in the
same castable formulations (CC, MCC,
LCC, ULCC) swapping “one To one”
with SECAR ® 71.
KIAL, Kolkata, India
Kerneos Corner
Refractory Technical Campus at Lyon,
France
Kerneos organized a three day
“Refractory Technical Campus” during
10-12th July’12 at their “Research
& Technology Centre” in Lyon,
France. Prime objectives were to
have better market and technological
understanding of the environment
in which Kerneos products are used
especially in the context of steel plant
applications, better dialogue with
customers about their products and
applications and the implications
for calcium aluminate cements. All
the market managers around the
globe participated in the programme.
Prasanta Dutta from Kerneos India took
part in the programme to decode the
customers’ need in the region.
Workshop at Vizag
Kerneos and the Indian Ceramic Society
(ICS) Vizag would be conducting a one
day workshop on improving castable
refractories with calcium aluminate
cement on August 9, 2012. With a
participation of approx. 150 delegates
the workshop will primarily benefit
the small scale industries producing
refractory castables in and around
Vizag and Rajamundry.
Kerneos is the world leader in calcium
aluminate technology and a key supplier
to refractories, steel and construction
industry.”With state-of-the-art plants
in almost all parts of the continent,
Kerneos is expanding its activities in
India with adaptable products for the
country and production facilities” stated
AK Tambe, Honorary Secretary of ICS
Vizag Chapter.

ROLE OF CALCIUM ALUMINATE CEMENT TO OPTIMISE CASTABLE PLACING
AND HARDENING
INTRODUCTION
Technical managers of many castable
manufacturing companies have the
experience of being called by the customers
or their own marketing team complaining
about too rapid or delayed setting. Often
the installers take care of the quick
stiffening or rapid flow decay with excess
water addition severely compromising the
final performance. For delayed setting
the technical persons need to run to the
installation site with packets of additives
to face the disgruntled customer, who
is then sceptical to meet his installation
schedule. The optimisation of the placing
and hardening properties is not easy
considering several factors, such as effect
of ambient temperature, quality of the
matrix phase components, their interaction
and aging of the mix. This article will discuss
role of calcium aluminate cement, which a
castable manufacturer often suspects first
when he faces such a situation.
Calcium Aluminate Phases And Reactivity:
The mineralogy of a calcium aluminate
cement determines its reactivity to a large
extent. The cement does never consist of
a single phase; rather it is a combination
of several phases. The phase composition
depends upon many parameters, although
the chemistry may be considered the most
important. The reactivity of the different
phases is shown in the table 1 [1], which
shows that the reactivity increases with the
increase of lime %.
Calcium monoaluminate (CA) is the
most desirable phase, as it develops the
highest strength among the phases during
the short time available for hydration of
refractory concrete. It takes time to initiate
setting; however, it develops strength
rapidly after initial set. It has a high melting
point (1600°C). Calcium dialuminate
(CA 2
), although more refractory than
CA, has slower reactivity, however, it can
improve with increase in temperature.
Calcium hexa aluminate (CA 6
) is a non
reactive phase and often it forms as a
reaction product in high purity alumina
castable. Appropriate combination of the
phases is essential to get desired reactivity.
When Calcium Aluminate cements are
placed in water they dissolve and form
ionic species. The relative ratio of C/A ions
depends upon the starting mineralogy.
The kinetics depend upon the ratio of C/A
and the temperature.
CA Ca 2+ + Al(OH) -
4
Table 1: The reactivity of the various calcium aluminate phases
Nucleation and massive precipitation of Table 2: Hydration of calcium monoaluminate
C= CaO, A= Al 2
O 3
hydrates continue following dissolution.
The temperature and solubility of the
Temperature Hydration Reaction
hydrates determine the type of hydrate
27°C 3CA + 12H C 3
AH 6
+ 2AH 3
Importance of regularity:
To get regular reactivity from a cement, which
is essential to get the desired placing properties
of castables, it is essential to have a consistent
mineralogy of the cement. If the process
of cement manufacturing is too variable
to produce a reliable quality, the castable
properties will vary making it impossible to
control the placing and hardening properties
Choice of calcium aluminate cement to
optimise castable placing properties:
One type of calcium aluminate
cement is known to be used in several
applications for long in India. However,
the recent developments allow castable
manufacturers benefit from adapted
products, which are not only suitable for
specific climates, but also optimized for
the castable type, such as conventional
or low cement. Examples are shown with
adapted products such as Secar® 70V for
conventional castables and Secar® 68V
for low cement castables with natural raw
materials and silica fume.
Usage qualities of conventional castables
and Secar ® 70V:
The usage qualities of conventional
castables include long working time,
yet rapid strength development, good
mechanical strength, rheology compatible
with common installation methods i.e.
vibration casting, patching and gunning,
stable placing properties even at high
ambient temperatures. Secar ® 70V, an
adapted cement for conventional castables
addresses all these requirements. Figure 1
shows that Secar ® 70V based 86% alumina
conventional castable (table 3) develops
good flow with lower water addition than
other reference cements and retain some
flowability after 60 minutes unlike other
cements. Although Secar ® 70V-containing
castables develop longer working time, it
G. Bhattacharya*, B. Valdelièvre* and C. Parr.
*Kerneos, Kolkata, India
C 3
A C 12
A 7
CA CA 2
CA 6
C/A 3 1.7 1 0.5 0.2
Reactivity at 20°C Very rapid Fast Slow Very slow None
F
(temperature
+ time)
2CAH 10
C 2
AH 8
+ AH 3
+ 9H
3C 2
AH 8
2C 3
AH 6
+ AH 3
+ 9H
develops strength rapidly (Figure 2). Not
only at the ambient temperature, Secar ®
70V based castables develop higher
mechanical strength throughout the
temperature range from 110°C to 1400°C
(Figure 3).
Table 3: Composition of 86% alumina
conventional castable
Raw materials Size Weight %
Chinese Bauxite 1-5 mm 44
Chinese Bauxite & BFA < 1 mm 35
Calcined alumina 6
Calcium aluminate cement 15
Typical water% 9-10
Vibration flow %
140
120
100
80
60
40
20
®
Secar 70V_9,1% water
B_10% water
C_10.3% water
0
0 30 60
Time mins
Figure 1: Vibration flow as a function of time for
86% alumina conventional castable with Secar ®
70V and other reference cements (B, C) at 35°C
CCS 6h (MPa)
20
18
16
14
12
10
8
6
4
2
0
Secar ® 70V_9,1%
Water
B_10%
Water
C_10.3%
Water
Figure 2: CCS after 6h for 86% alumina castable
with Secar ® 70V and other reference cements
(B, C) 35°C

Compressive Strength MPa
70
60
50
40
30
20
10
0
Secar 70V_9,1% water
B_10% water
C_10,3% water
110°C 800°C 1100°C 1400°C
Figure 3 : CCS as a function of temperature for 86%
alumina castable with Secar ® 70V and other reference
cements (B, C)
Table 4: Composition of bauxite and silica fume based low cement
castable
Raw materials Size Weight %
Chinese Bauxite 1-5 mm 50
Chinese Bauxite & sillimanite < 1 mm 38
Silica fume 6
Secar ® 68V 6
HMP 0.12
Typical water% 4.5-5.5
Usage qualities of low cement castables and Secar ® 68V:
The low cement castables are more
sensitive to water addition levels than
conventional castables. High ambient
temperature conditions, which prevail
in most part of India for a major part
of the year, pose a challenge to get
sufficient flow for casting low cement
castables with low water addition. Not
only the development of flow, but also
its retention is very important to complete
the installation properly. Therefore,
the castables require functionality to
stand the high temperature conditions
to develop sufficient flowability and
long working time for casting. Once the
casting is complete, the castable needs
rapid strength development, so that it
can be demolded and heated up without
any delay. Also, the castable requires
good mechanical strength throughout
the temperature range to meet various
application requirements. Secar ® 68V is
adapted to have these functionalities
in low cement castables with natural
aggregates and fume silica. It develops
appreciable flow with low water addition
even at high ambient temperature and
retains for sufficiently long time for
casting (Figure 4) in common low cement
castable formulations (table 4). Despite,
high flow for long time, the 6h strength
is quite high which shows rapid strength
development (Figure 5). Not only at the
ambient temperature, Secar ® 68V based
low cement castables develop high
strength throughout a large temperature
range (Figure 6).
140
70
3.6
210
Vibration flow %
120
100
80
60
40
Water 5.2%
20
Exclusion zone
Water 4.9%
0
0 20 40 60 80 100 120 140
Time mins
6hr Compressive Strength MPa
60
50
40
30
20
10
0
35.2
22.8
5.2%
4.9%
Water
Water
Water 5.2% Water 4.9%
3.5
3.4
3.3
3.2
3.1
3
2.9
6hr Modulus of Ruture MPa
CCS : MPa
180
150
120
90
60
30
Water 5.2%
Water 4.9%
0 400 800 1200 1600
Temperature °C
Figure 4: Vibration flow as a function
of time for a bauxite based low cement
castable with Secar ® 68V at 35°C with
variation o f water addition
Conclusion:
Calcium aluminate cement is the
most vital component of a castable.
Its reactivity directly controls the key
placing and hardening parameters,
such as flow as a function of time and
Figure 5: CCS and MOR after 6h for a bauxite
based low cement castable with Secar ® 68V
at 35°C with variation of water addition
strength development. The consistency
in reactivity can only be obtained with
the use of very regular cement quality.
However, the cement reactivity varies
with temperature and the role of cement
Figure 6: CCS as a function of temperature
for a bauxite based low cement castable with
Secar ® 68V with variation of water addition
is different for conventional and low
cement castables. The new cements with
adapted functionalities take care of these
requirements of castables in a better way.
References:
[1] C. Parr, “Calcium aluminate cement – what happens when things go wrong?”, presented at IRE
annual conference, Rotherham, UK, 2008
For more details mail : goutam.bhattacharya@kerneos.com
Kolkata Office : KERNEOS INDIA
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Head Office : KERNEOS S.A
8 Rue Des Graviers, 92521 Neuilly Sur Seine Cedex, France, Tel: +33 1 46 37 90 00 Fax: +33 1 46 37 92 00