FIELD OF THE INVENTION
The present invention relates to development of alumina magnesia carbon (AMC)
composite/bricks to enhance lining life of ladle. More particularly, the AMC brick lining at
the ladle bottom impact area favour limiting the wear rate of the bottom lining layer even
at high operating temperature in the range of 1600-1700°C with repeated cycles of heat
making and high impact pouring of molten steel from BOF. Advantageously, also the AMC
lining favour improved permanent linear change (PLC) % on repeated firing due to high
volume of spinel forming and thus enhancing Ladle lining life from conventional 85-90
heats using MgO-C (MC) bricks to over 120 and up to 129 heats and favoured lower wear
rate in the range of 1.7 to 2.0 mm/heat as compared to conventional 2.7 to 3 mm/heat
with improved selective lining arrangement/pattern for ladle comprising AMC bricks for
impact area of ladle bottom. The present invention thus specifically provides for improved
strength and life of the impact area of the bottom lining of steel ladles and thus decreasing
down time due to need for less frequent change of refractory lining, especially of the
impact area of the ladle bottom and resultant improvement in productivity favoring wide
industrial application in steel melting shops/plants.
BACKGROUND ART
It is well known in the existing art of steel melting in large steel plants that for refractory
lining of the steel ladles, magnesia carbon (MC) bricks of different qualities are generally
used for lining different areas of the ladle in order to enhance service life of ladle lining for
larger number of heats in a go. The average lining life of 150 T steel ladles of Rourkela
steel plant (RSP) has been found to be 89 heats conventionally. In order to enhance
availability of steel ladles for higher steel production it is necessary to increase lining life of
steel ladles.
It has been experienced and revealed while exploring the wear profiles of refractory linings
laid on inside of the ladle that the bottom impact pad is one of the critical areas of concern
for steel ladle lining with regard to wear rate due to high impact of liquid metal poured and
repeating cycles of ladle heats at high temperatures. Different qualities of magnesia
carbon bricks have been tried in this area but much improvement could not be achieved.

The Bricks for lining of ladle bottom for the impact pad portion area have to withstand the
impact of stream of liquid steel tapped directly from BOF from a height of 10m. This also
creates severe thermal shock in bricks. Magnesia carbon bricks are very good in slag
corrosion resistance but have moderate thermal shock resistance and thus limiting the
ladle life and poor productivity. In ladles with MgO-C bricks in bottom impact area require
replacement or heavy deposition of castable material for leveling during mid campaign
repairs at about 50 and 70 heats to reach a final life of about 90 heats.
There has therefore been a persistent need in the related art of steel making and allied
processes for developing a type of refractory lining for the inside surfaces of ladle,
particularly the impact area of ladle bottom, directed to enhance the ladle life in terms of
increased number of heats and thus favouring repeating cycles of firing without any mid
campaign repair or replacement of the lining even at high operating temperature of 1600-
1700°C. The process of developing and application of the AMC bricks for lining of the
impact pad portion of the ladle bottom would on one hand reduce surface wear of lining
and progressively improve the physical properties of the refractory lining of ladle through
successive heats and on the other hand reduce wear rate, resist thermal shock and thus
avoiding the down time to thereby substantially enhancing the ladle life (number of heats)
for relining and increasing the productivity of the steel melting shop.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide a alumina magnesia carbon
(AMC) composite/brick adapted specifically for lining bottom impact pad to enhance ladle
life in terms of increased number of heats without lining change or less number of mid
campaign repair.
Another object of the present invention is directed to developing AMC bricks for impact pad
of the ladle bottom in order to withstand high impact load for metal pouring from BOF and
also with stand thermal shock even at high operating temperature range of 1600-1700°C
during repeating cycles of successive heats poured in ladle.
A further object of the present invention is directed to developing AMC bricks for impact
pad of the ladle bottom in order to withstand high impact load and enhanced ladle life
adapted to favour lowering wear rate as compared to conventional MC brick lining.

A still further object of the present invention is directed to developing AMC bricks for
impact pad of the ladle bottom in order to withstand high impact load and enhanced ladle
life wherein spinel formation is suitably controlled by adjusting amount of magnesia and
alumina as well as their particle (grain) size distribution so that the working surface of the
brick expands optimally with repeated heating, thus favoring enhanced ladle/lining life
capable to operate increased number of heats.
A still further object of the present invention is directed to developing AMC bricks for
impact pad of the ladle bottom in order to withstand high impact load and enhanced ladle
life wherein spinel formation is selectively controlled by optimising refractory composition
through repeated heats such that the Permanent Linear Change (PLC %) is maximized for
optimum ladle life through repeating heating cycles.
A still further object of the present invention is directed to developing AMC bricks lined
ladles adapted to withstand high impact load and enhanced ladle life wherein said
optimised composition and brick lining enhance the effective number of heats to up to 129
heats, with selective lining pattern comprising AMC bricks for the ladle bottom impact
area, along with MC bricks having fused magnesia (FM) and sea water magnesia (SWM) of
varied carbon content for different portions of the ladle lining for surroundings.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided Alumina,
magnesia and carbon (AMC) based refractory comprising :
alumina in amount of 50 to 80% by wt.;
magnesia in an amount of 5 to 40% by wt.;
carbon in an amount of 2 to 15 % by wt.; and
liquid binder preferably phenol formaldehyde resin material in an amount of 2 to 8 % by
wt.

Another aspect of the present invention is directed to Alumina, magnesia and carbon
(AMC) based refractory comprising an antioxidant preferably aluminium metal powder in
amount of 0.1 to 5 % by wt.
A still further aspect of the present invention is directed to Alumina, magnesia and carbon
(AMC) based refractory wherein the particle size distribution of Alumina and Magnesia
comprises:
Alumina
3 to 5mm 20-30
1 to 3mm 20-30
0 to lmm 20-30
0 to 0.17mm 20-30
Magnesia
0 to 0.5mm 0-20
0 to 0.1mm 0-20
A still further aspect of the present invention is directed to Alumina, magnesia and carbon
(AMC) based refractory having



According to another aspect of the present invention is directed to Alumina, magnesia and
carbon (AMC) based refractory comprising alumina, magnesia and carbon bricks.
A still further aspect of the present invention is directed to Alumina, magnesia and carbon
(AMC) based refractory having:
bulk density (g/cc) in the range of 3.1 to 3.4
Ap. Porosity (vol %) in the range of 2 to 5
Coked AP (vol % ) in the range of 6 to 12
Coked BD (g/cc) in the range of 3.1 to 3.3;
CCS (kg/cm2) in the range of 400 to 600;

HMOR-1400°C C/30 min (kg/cm2) in the range of 50 to 100 ;
Decarburised area (%) in the range of 30 to 50 ;
Decarburised thickness (mm) in the range of 5 to 10;
PLC (%)-1600°C/2Hr 0f 3 to 6;
According to yet another aspect of the present invention is directed to a process for the
manufacture of alumina, magnesia and carbon refractories/bricks comprising:
selectively mixing said alumina of specified grain size and distribution and in amounts of
80 to 95%, magnesia of specified grain size distribution and in amounts of 5 to 20% with
graphite in amounts of 2 to 15% and liquid resin in amount of 2 to 8% with or without
aluminum metal powder in amounts of up to 5 %;
the mix thus obtained is thereafter kept in a covered area for a specified duration
preferably 12 to 48 hours for aging and pressed at a specified pressure in the range of
500 to 2500 kg/cm2 with de-airing upto 10 to form alumina magnesia carbon
composite/bricks.
A still further aspect of the present invention is directed to said process for the
manufacture of alumina, magnesia and carbon refractory/bricks comprising curing or heat
treating the composite/bricks in the temperature range of 50 to 400°C for a period of 10 to
72 hrs.
Another aspect of the present invention is directed to Steel ladle comprising:
a refractory lining adapted for achieving higher target life comprising at least the bottom
impact area of the ladle being obtained of alumina, magnesia and carbon refractory/bricks.
A still further aspect of the present invention is directed to Steel ladle wherein the
refractory lining comprises of:
the bottom impact area of the ladle obtained of alumina, magnesia and carbon
refractory/bricks as claimed in anyone of claims 1 to 6 and the remainder of the bottom of
the ladle being obtained of MC bricks having FM + SWM (7% C) ;

the side surfaces of the lining comprising of an upper top region obtained of MC bricks
having FM + SWM (9%C) and the lower region covering about 2m of the height being
obtained of MC bricks having FM + SWM (8%C).
The present invention and its objects and advantages are described in further details with
reference to the accompanying example and figures.
BRIEF DESCRIPTON OF THE ACCOMPANYING FIGURES
Figure 1: is the illustration showing the comparative arrangement of the ladle lining for
existing vis-a-vis modified lining patterns with conventional as well as the AMC bricks of
the present invention for ladle bottom impact area, of 150T steel ladle.
Figure 2: is the graphical plot of the PLC% for different compositions used for
manufacturing the AMC bricks according to the invention, to achieve optimum composition
and lining performance on repeating heats at 1600°C for 2hrs.
Figure 3: is showing the lining pattern of trial ladles and the wear rate achieved for
different portions of refractory lining on trial heats including the impact pad portion of ladle
bottom according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to developing a novel alumina magnesia carbon (AMC)
bricks for lining of steel ladle, especially to improve strength, and life of refractory bricks
for the impact pad area of the ladle bottom area and a process for manufacturing said AMC
bricks demonstrating desired higher impact and thermal strength properties of ladle lining
on repeated heat cycles to achieve enhanced ladle life in terms of number of heats. Resin
bonded alumina magnesia carbon (AMC) brick was developed for bottom impact pad with
alternative formulations/chemistry in order to ascertain the optimized composition and end
properties after a number of trials conducted at one of the steel plants of the applicants

where such bricks has been in house. A small capacity (300kg) mixer is installed and used
in Brick plant for making resin bonded mixes. About 2T of AMC bricks are manufactured
for bottom impact pad of each ladle. These AMC bricks along with magnesia carbon (MC)
bricks were installed in ladles in selective specified pattern for conducting trial with
alternative compositions and performances are evaluated for successive repeating cycles
of heats for optimizing ladle life in actual service, with or without the mid campaign
change of bottom impact area.
Reference is first invited to accompanying Figure 1, that illustrates the comparative
arrangement/pattern of the ladle lining for existing vis-a-vis modified lining patterns with
conventional as well as the AMC bricks of the present invention for ladle bottom impact
area, of 150T steel ladle. It may be noted that while the SWM of varied carbon content of
7-9% has been used for the conventional ladle refractory lining, the new pattern makes
use of FM with SWM. The side lining modification has been done to get full potential of
AMC bricks in bottom and finally to achieve higher ladle lining life with selective
provisioning of AMC for the impact area of ladle bottom in the modified lining pattern of
the present invention directed to enhance ladle lining life.
Because of improved performance of bottom impact area, lining life of ladles could be
extended to around 120 heats and thus favouring wide scale production and application of
AMC bricks for bottom impact area of steel ladles as a regular item that is manufactured in
captive brick plant of steel plant.
The present invention is directed to developing a manufacturing process for suitable
formulation of AMC bricks by using specified quality of alumina, magnesia and graphite in
selective proportions to get substantial amount of spinel after reaction at high
temperatures in the range of 1600-1650°C during use. This spinel formation has been
suitably controlled by adjusting amount of magnesia and alumina as well as their particle
(grain) size distribution in such a way that the working surface of the brick expands
optimally with repeated heating.
The different alternative embodiments of the invention directed to the process of
manufacturing AMC bricks involving preparing mix of different compositions of components
are illustrated with the help of following illustrative example:

EXAMPLE:
The process of developing AMC bricks of selective composition and optimized properties
ensuring desired end results.
a. The starting material for the process of manufacturing alumina magnesia carbon (AMC)
bricks according to the present invention comprise the input raw materials comprising
alumina, magnesia, graphite and resin of selective proportion/concentration and
particle/grain size conforming to specified quality as follows:



b. The process of manufacturing alumina magnesia carbon (AMC) bricks involves providing
specified amount of alumina in the range of 50-80% having specified grain size distribution
and also specified amount of magnesia in the range of 5-40% of specified grain size
distribution which are mixed in a mixer with specified amount of graphite in the range of
2-15%, specified amount of aluminium metal powder in the range of 0.1-5% and specified
amount of liquid resin in the range of 2-8%, such that a homogeneous mixture is obtained
for pressing bricks.
c. The process of manufacturing alumina magnesia carbon (AMC) bricks according to the
present invention wherein in said mixing process coarse fractions of refractory grains are
mixed with liquid resin in a high intensity mixer for specified time of 2-20 minutes and
then subjected to further mixing with fine fractions of refractory grains, graphite and
aluminium for specified time duration of 2-30minut.es.
d. The mix so obtained in the mixer is discharged and kept in a covered area for specified
duration of 12 to 48 hrs for aging and pressed in hydraulic or other type of press at
specified pressure in the range of 500-2500kg/cm2 with specified number of de-airing e.g.
0-10 to form alumina magnesia carbon (AMC) bricks.
e. The alumina magnesia carbon bricks thus produced are cured or heat treated in a kiln
following a specified time duration of 10-72 hrs in the temperature range of 50-400°C
regime to get alumina magnesia carbon bricks ready for application in refractory lining of
ladle.
f. The different alternative batch compositions of mix comprising the basic input
ingredients used to produce AMC bricks of the invention for lining of ladle, particularly at

impact area of the ladle bottom in order to achieve desired optimum strength, wear rate
and thermal shock resistance properties are subjected to laboratory scale trial. Different
such formulations of alumina magnesia carbon (AMC) bricks are made with varied amount
of magnesia and antioxidant (aluminium metal powder) and their batch composition
marked as AMC-1, AMC-2 & AMC-3 and corresponding end properties achieved are given
in following Table 1 and Table 2 respectively, said bricks being used in an unique lining
pattern along with Magnesia Carbon bricks (MC) in bottom impact area of steel ladles.



At high operating temperature, the alumina present in the mix reacts with magnesia and
forms MgO.AI2O3 spinel. Such spinel formation increases volume. Permanent linear change
(PLC) after repeated cycles of firing at 1600°C for 2hrs is shown in accompanying Figure
2. It has been observed that linear expansion of the 3 formulations e.g. AMC 1, 2 & 3
demonstrate uniformity of properties with respect to PLC% during the 1st cycle but the
behaviour change on repeated firing through following three successive cycles. It is
further observed that AMC 1 shows relatively higher value of PLC% in the order of 6.33
compared to other formulations identified as AMC 2 and AMC 3.
Four plant scale trials were conducted in 150 ton ladle, were conducted with these bricks
as per modified lining design. In the 1st trial full potential of the lining could not be
attained as the ladle went out of commission/operation due to skull formation after 90
heats. In the 2nd trial, a lining life of 120 heats could be achieved which was highest with
in-house bricks in RSP. Wear profile indicated that there was potential for further heats
with same lining. This life (120 heats) was achieved without changing any brick in bottom
impact area.
In the 3rd trial a new record life of 129 heats has been achieved which is the highest steel
ladle lining life among all the different steel plants of the applicants. In 4th trial ladle
became inoperative due to erosion in well block area after 118 heats, which could otherwise
carry out a few more heats. However, in 3rd and 4th trial, a part of bottom impact area was
replaced after 107 and lOlheats to achieve higher targeted life.
It has also been experienced during the successive trials that in the 1st trial full potential of
the lining life could not be ascertained as the ladle broke down due to skull formation after
90 heats.

However, in the 2nd, 3rd and 4th trials, ladle lining life of 120, 129 and 118 heats are
achieved where bottom impact area of ladle is lined with the alumina magnesia carbon
(AMC) bricks developed and used for the purpose. Both magnesia carbon (MC) and AMC
bricks has been manufactured at in-house brick plant and applied for lining of the 150 ton
ladle for trial. Accompanying Figure 3, shows the lining pattern arranged in refractory
lining of the ladles put on trials. It is further studied from the measurement of remaining
lining thickness, that wear rate per heat is determined to be lower as compared to the
conventional lining pattern using magnesia carbon bricks at the impact area of the ladle
bottom. The corresponding results are indicated in the following Table-3.

It is thus clearly apparent from the Table 3 above that the AMC bricks produced following
the process of the present invention and used in the lining pattern for impact area of 150
ton ladle bottom according to the present invention, is capable to withstand the impact
load of molten metal poured from the BOF, resist the thermal shock as well as controls the
wear rate and thereby enhance the ladle lining life from existing maximum life of 85-90
heats to over 120 heats and up to a maximum of 129 heats. The AMC bricks and its
process of manufacture thus would favour wide scale application in steel ladles of large
capacities used in large steel plants enhancing yield and productivity by extending the
ladle life in terms of number of repeating heats it is able to sustain in continuous
succession, with or without any mid campaign change of the refractory lining, with
advantageous low wear rate of 1.7-2.0 mm/heat, with significant economic advantage.

We Claim:
1. Alumina, magnesia and carbon (AMC) based refractory comprising :
alumina in amount of 80 to 95% by wt.;
magnesia in an amount of 5 to 20 % by wt.;
carbon in an amount of 2 to 15 % by wt.; and
liquid resin material in an amount of 2 to 8 % by wt.
2. Alumina, magnesia and carbon (AMC) based refractory as claimed in claim 1 comprising
an antioxidant preferably aluminium metal powder in amount of 0.1 to 5 % by wt.
3. Alumina, magnesia and carbon (AMC) based refractory as claimed in anyone of claims 1
or 2 wherein the particle size distribution of Alumina and Magnesia comprises:
Alumina
3 to 5mm 20-30
1 to 3mm 20-30
0 to 1mm 20-30
0 to 0.17mm 20-30
Magnesia
0 to 0.5mm 0-20
0 to 0.1mm 0-20
4. Alumina, magnesia and carbon (AMC) based refractory as claimed in anyone of claims
1 to 3 having

Alumina, magnesia and carbon (AMC) based refractory as claimed in anyone of claims
1 to 4 comprising alumina, magnesia and carbon bricks.
6. Alumina, magnesia and carbon (AMC) based refractory as claimed in anyone of claims
1 to 4 having:
bulk density (g/cc) in the range of 3.1 to 3.4;
Ap. Porosity (vol %) in the range of 2 to 5;
Coked AP (vol % ) in the range of 6 to 12;
Coked BD (g/cc) in the range of 3.1 to 3.3;
CCS (kg/cm2) in the range of 400 to 600;
HMOR-1400°C C/30 min (kg/cm2) in the range of 50 to 100;
Decarburised area (%) in the range of 30 to 50;
Decarburised thickness (mm) in the range of 5 to 10;
PLC (%)-1600°C/2Hr of 3 to 6;
7. A process for the manufacture of alumina, magnesia and carbon refractories/bricks as
claimed in anyone of claims 1 to 6 comprising:
selectively mixing said alumina of specified grain size and distribution and in amounts of
50 to 80%, magnesia of specified grain size distribution and in amounts of 5 to 40% with
graphite in amounts of 2 to 15% and liquid resin in amount of 2 to 8% with or without
aluminum metal powder in amounts of upto 5 %;
the mix thus obtained is thereafter kept in a covered area for a specified duration
preferably 12 to 48 hours for aging and pressed at a specified pressure in the range of
500 to 2500 kg/cm2 with de-airing upto 10 to form alumina magnesia carbon
composite/bricks.
8. A process for the manufacture of alumina, magnesia and carbon refractory/bricks as
claimed in claim 7 comprising

curing or heat treating the composite/bricks in the temperature range of 50 to 400°C for a
period of 10 to 72 hrs.
9. Steel ladle comprising:
a refractory lining adapted for achieving higher target life comprising at least the bottom
impact area of the ladle being obtained of alumina magnesia carbon (AMC)
refractory/bricks as claimed in anyone of claims 1 to 6.
10. Steel ladle as claimed in claim 9 wherein the refractory lining comprises of:
the bottom impact area of the ladle obtained of alumina magnesia carbon (AMC)
refractory/bricks as claimed in anyone of claims 1 to 6 and the remainder of the bottom of
the ladle being obtained of magnesia carbon (NIC) bricks having FM + SWM (7% C) ;
the side surfaces of the lining comprising of an upper top region obtained of magnesia
carbon (MC) bricks having FM + SWM (9%C) and the lower region covering about 2m of
the height being obtained of magnesia carbon (MC) bricks having FM + SWM (8%C).
11. Alumina, magnesia carbon (AMC) based refractory, its process of manufacture and
Steel ladle lining obtained thereof substantially as herein described and illustrated with
refernce to the accompanying examples and figures.

Alumina magnesia carbon (AMC) refractory bricks for bottom impact pad to enhance lining
life of ladle. More particularly, the AMC brick lining at the ladle bottom impact area favour
limiting the wear rate of the bottom lining layer even at high operating temperature in the
range of 1600-1700°C with repeated cycles of firing and high impact due to pouring of
molten steel from BOF. Advantageously, also the AMC lining favour improved PLC % on
repeated firing due to high volume of spinel forming and thus enhancing Ladle lining life to
over 120 and upto 129 heats and favoured lower wear rate in the range of 1.7 to 2.0
mm/heat with improved selective lining arrangement/pattern comprising AMC bricks for
impact area of ladle bottom, along with magnesia carbon (MC) having fused magnesia
(FM) and sea water magnesia (SWM) of varied carbon contents for different portions of
ladle. The present invention thus provides for improved strength and life of steel ladles
reducing down time and resultant improvement in productivity.