Title of Invention

AN IMPROVED AL2O3-SIC-C REFRACTORIES BASED LINING PATTERN FOR HOT METAL TRANSFER LADLE TO REDUCE MOUTH JAM AND BOTTOM BUILD-UP AND LADLE WITH LINING

Abstract This invention relates to the development of AI2O3-SiC-C refractories based lining design for hot metal transfer ladle and ladle for hot metal transfer comprising AI2O3-SiC-C refractories based lining structure of predetermined shape to reduce mouth jam and bottom build-up. More specifically, it is concerned with the design of hot metal transfer ladle having lining of AL2O3-SiC-C bricks in mouth area and AI2O3-SiC-C castable in top ring and spout. The new lining design contributes for lesser mouth jam and bottom build-up for easy deskulling. The use of AI2O3-SiC-C refractories based lining reduced greatly the maintenance repairs, allowing lower cost, reducing men hour/power need, saving energy and refractory material, improving the availability and the safety for the operation.
Full Text 2
DEVELOPMENT OF AI2O3-SiC-C REFRACTORIES BASED LINING DESIGN FOR HOT METAL TRANSFER LADLE TO REDUCE MOUTH JAM AND
BOTTOM BUILD-UP
FIELD OF THE INVENTION
This invention relates to the development of AI2O3-SiC-C refractories based lining design for hot metal transfer ladle to reduce mouth jam and bottom build-up. More specifically, it is concerned with the design of hot metal transfer ladle having lining of AI2O3-SiC-C bricks in mouth and bottom conical areas and AI2O3-SiC-C castable in top ring and spout. The new lining design contributes for lesser mouth jam and bottom build-up for easy deskulling. The use of AI2O3-SiC-C refractories based lining reduced greatly the maintenance repairs, allowing lower cost, reducing men hour/power need, saving energy and refractory material, improving the availability and the safety for the operation.
BACKGROUND OF THE INVENTION
In the metal casting industry, it is customary to employ metal casting vessels, such as hot metal transfer ladle, hot metal ladles, etc., as means that serve to transfer various molten metals (hot metals). To prevent heat loss and premature solidification of the metals, the metal casting vessels are prevented from contacting with corrosive metals and/or slags by lining the vessels with heat-insulating refractory bricks.
JP 9145258 describes lining structure of hot metal ladle that prevents exfoliation and damage of a mending material provided by an adding construction, by uniformizing the damaging speed of a lining. The lining structure of hot metal ladle is so constructed that a slag line part and the part below it are lined monolithically with unshaped refractory of a material Al2 O3 - SiO2 -SiC wherein an SiO2 component in the whole of refractory aggregate is made 3-60wt.%. In this case, the rate of the SiO2 component in the whole of the refractory aggregate of a layer is lower than the slag line part in the direction of the height of the side wall

3
which is made larger by 3wt.% or above than that in the slag line part within the sphere of the aforesaid material and, moreover, both of the stag line part and the layer lower than this part are made to contain metal short fibers of 0.5-5wt.% by outer percentage to 100wt.% of the refractory aggregate.
JP 4325466 describes unshaped refractory and stainless hot metal ladle lined inside that is capable of labor saving and resource economization by additional repairing. An unshaped refractory containing by weight excepting water content to be added, 1 to 20% silicon carbide filler, 1 to 15% carbon, 0.5 to 5% alumina cement and 3 to 13% superfine powder constituted of alumina and silica is formed. The unshaped refractory in which its service life is not inferior to that of a shaped refractory, which has heretofore been used as the lining material for a stainless hot metal ladle can be obtained, and heavy operations in accordance with construction can be eliminated.
EP0184634 describes the ladle for receiving and, where necessary, for subsequent treatment and/or transportation of hot, molten, metals which are poured from a preceding melting unit into the ladle, which a lining made of high-temperature-resistant material such as, for example, chamotte bricks which lie adjacent to one another and cover the base and side walls of the ladle and have, at the point of impact of the pouring stream of molten metal, an impact element which projects above the adjacent surface of the lining , characterized in that the impact element is a domed element inset into the lining , of which the domed surface is directed against the pouring stream of molten metal and blends without a step into the surface of the adjacent lining and of which the smallest diameter D or the smallest edge length at the transition to this surface is larger than the diameter (d) of the pouring stream of molten metal at the point of impact.
GB 576246 discloses a ladle for molten metal comprises an outer metallic shell, a refractory lining nesting in a mould of tin or other soft metal and secured in place by a detachable ring, an outlet port in the lower portion of the ladle and a valve. The valve comprises a metallic head covered by a refractory coating and a stem, detachably secured to the head and covered by a refractory coating. Movement

4
of the valve is controlled by a bridge lever, pivoted to the ladle and to the valve stem and a hand lever pivoted to the ladle and connected to the bridge lever by a link. To limit the extent to which the valve may be moved, or to hold the valve against operation an upstanding guide is provided having a number of vertically spaced apart perforations, into any of which a pin may be inserted to contact an edge of the bridge lever.
In summary, previous attempts or approaches have been made to develop suitable preheatable insulating refractory liners. Heretofore no satisfactory preheatable heat-insulating refractory liner has been developed which can overcome the problems aforementioned. The present invention narrated the development of AI2O3-SiC-C refractories based lining designed for hot metal transfer ladle to reduce mouth jam and bottom build-up. More specifically, it is concerned with the design of hot metal transfer ladle having lining of AL2O3-SiC-C bricks in mouth and bottom conical areas and AL2O3-SiC-C castable in top ring and spout.
SUMMARY OF THE INVENTION
In Basic Oxygen Furnace shop of Durgapur Steel Plant, hot metal transfer ladle (Capacity 140T) is used for carrying hot metal (HM) from Mixer to Basic Oxygen Furnace. Study of the existing practice indicated that the newly relined ladles are capable of transferring 140T hot metal but its capacity gradually reduces due to mouth jam and bottom build up by increasing tare weight from initial 40 - 43T to as high as 60 - 65T after reaching a lining life of 100 - 150 heats. At this stage the ladle is not capable of transferring hot metal more than 120 - 125T due to limitation of crane capacity and is declared down for jam removal and refractory repair/maintenance.
Presently 120T of hot metal is charged for attaining Basic Oxygen Furnace heat weight of 118T. For increasing the Basic Oxygen Furnace heat weight to 125 -130T, the amount of hot metal required to be charged was about 125 - 132T. Thus hot metal transfer ladle capacity became a constraint for charging increased quantity of hot metal.

5
In brief, the present invention seeks to alleviate the above-mentioned problems and shortcomings of the present start of the art through the discovery of novel AL2O3-SiC-C refractories based new lining design for hot metal transfer ladle to reduce mouth jam and bottom build-up and methods of use thereof. In a preferred embodiment, the present invention is directed to a AL2O3-SiC-C refractories based lining for a hot metal transfer ladle is capable of transferring hot metal as per ladle capacity due to less increase in tare weight, comprising a liner structure of predetermined shape, the liner structure comprising a molded uniform mixture containing a particulate refractory component comprised of AL2O3-SiC-C refractories.
DETAILED DESCRIPTION OF THE INVENTION
The object of the invention is to develop AL2O3-SiC-C refractories based lining design for hot metal transfer ladle to reduce mouth jam and bottom build-up.
A further object of the invention is to provide design of hot metal transfer ladle having lining of AL2O3-SiC-C bricks in mouth and bottom conical areas and AL2O3-SiC-C castable in top ring and spout.
A further object of the invention is to provide the new lining design that contributes for lesser mouth jam and bottom build-up for easy deskulling.
Yet another object of the invention is to provide new lining design that is capable of transferring hot metal as per ladle capacity due to less increase in tare weight.
Yet another object of the invention is to provide AL2O3-SiC-C refractories based lining that reduces greatly the maintenance repairs, allowing lower cost, reducing men hour/power need, saving energy and refractory material, improving the availability and the safety for the operation.

6
Finally, a last object of the invention is to provide a ladle, which is constructed so as to remain in good repair for a considerable length of time and having parts, likely to become worn or damaged, easily replaceable.
Heating and melting furnaces, smelting and refining furnaces, and the vessels used to carry hot metal and molten steel are all lined with refractories. The main reason why these furnaces and vessels cannot be used continuously is the need for repair and replacement as a result of wear of the refractory lining. In other words, the life of the refractories determines the life of furnaces and vessels. Refractories for iron and steel production are used under very severe conditions, which include not only elevated temperatures, but also thermal shock caused by abrupt temperature changes. Further, they must possess high-temperature strength and wear resistance to the large momentum of impinging and turbulent metal flow. Refractories must also have the chemical stability to withstand attack by hot metal, molten steel, slag, and various fluxes.
Refractories have a high melting point and good heat-insulating properties. Their basic composition comprises chemically stable substances such as magnesia, alumina, and silica, which do not easily react with steel slags or fluxes. When binders are mixed with these refractories, the mixture, when used as it is, is called a monolithic refractory; when pressurized, compacted, and fired, it is called firebrick. When compacted and tempered at a temperature around 250-400 *c under central atmosphere, it is called tempered bricks.
Because of the high temperatures, erosion from the stirred bath, and high corrosiveness of the metallurgical slag, high-alumina and magnesia based castable refractories are preferred for ladle linings. Still, life remains short (30 to 50heats). More recently, higher-temperature-capable oxide/carbon mixtures are being used to provide a balance of reasonable purity, high thermal shock resistance, and low erosion. Alternative refractories having longer life, lower cost, and safer disposal continue to be sought. In addition to use with porous plugs, tyueres, lances, and refractories, opportunities exist for advanced ceramics in ladle recuperators and impact pads. Impact pads are located on the bottom of the ladle and ultimately determine the life of the ladle. Materials

7
with higher strength capability at temperature, improved abrasion resistance, and high-thermal shock resistance are desired.
In almost all metal melting applications, refractory lined steel shell ladles are used to transport molten metal from the melting furnace to the pouring or casting operation. Ladles vary in size from 50-Ton capacity to 350 tons or larger in steel plants.
Within the last few years, steel industries have been under heavy pressure to reduce costs and improve quality in order to compete effectively in what has become increasingly a world market. Industries are continuing to take steps to modernize their production practices and improve their yields. In particular, the drive for clean steel has increased the desirability of transferring hot metal ladles in excess which can be achieved by development of new AL2O3-SiC-C refractories based lining. Among the benefits derived from new AL2O3-SiC-C refractories based lining are:
• The prevention of explosions, which can result from the sudden conversion
of moisture, entrapped in the ladle refractory, to steam when molten metal
is added.
• Elimination of metal solidification in the ladle (skulls) which requires
maintenance time and labor to re- move, and can affect metal quality and
pouring from the ladle.
• Reduced pouring temperatures with the attendant significant savings in
metal heating costs.
• Reduced thermal shock to the ladle lining, thus greatly increasing the lining
life.
• Improved lining life from controlled temperatures during drying of new
linings.
• Reduced temperature losses from molten metal during the continuous
casting or ingot teeming operation.
In recent years advances have been made in the design of Ladle. Through modem design and controlled operating practices, high maintenance costs

8
have been minimized and good life expectancy can be demonstrated from existing installations.
In order to reduce the mouth jam/bottom build up for holding 135 - 140T hot metal a new lining design of hot metal transfer ladle was developed. The ladle lining was modified to:
• Introduction of a new type AL2O3-SiC-C bricks in top 7 rings and lower 5
rings and AL2O3-SiC-C castable in top 3 rings and spout respectively for
easy deskulling.
• Use of 30% AL2O3 insulation brick as safety lining to reduce heat loss and
skull formation.
• Use of 40% AL2O3 high grog brick replacing conventional 38% AL2O3 fireclay
bricks in belly and bottom lining.
Preferably, the formulation of specification for AL2O3-SiC-C bricks/castable for hot metal transfer ladle is shown below in the Table-1.
Table -1: Refractories for top Rings and spout lining in HMT ladle

Type Properties Bricks Castable
AL2O3-SiC-C AL2O3(%) 50 60
SiC+ R.C (%) 12 10
CCS (Kg/Cm2) 350 300
B.D. (gm/cc) 2.80 2.75
Therefore, the new and vastly improved AL2C>3-SiC-C refractories based lining design for hot metal transfer ladle provide means for.
o Application of AL2O3-SiC-C bricks in mouth and bottom conical areas and AL2C>3-SiC-C castable in top ring and spout is a new concept for HM transfer ladle;
o The new lining design contributes for lesser mouth jam and bottom build-up for easy deskulling (Fig-1) and (Fig - 2).

9
o The new lining design is capable of transferring hot metal as per ladle
capacity due to less increase in tare weight. (Fig - 3) o The new lining design has helped increasing ladle availability by reduction of frequency of repair i.e. avg. 148 heats against for conventional ladle 110 heats (Fig - 4).
The new lining design has helped for less down time for repair of ladle compared to conventional ladle.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Referring now to the accompanying drawings, forming a part of this
specification:
Figurei is lining pattern of Modified vs. existing HM Ladle.
Figure 2 is modified lining of hot metal ladle at DSP.
Figure 3 is tare weight vs. life of conventional and modified ladle at DSP.
Figure 4 is repair frequency of conventional and modified ladle at DSP
The hot metal ladle body as shown in figure 4 is composed of (i) the shaft, which tapers outward from the top, (ii) the belly, which is a straight cylinder, (iii) the bosh, which tapers inward toward its bottom and is located immediately under the belly, and (iv) the hearth, at the bottom of the furnace. The shaft, belly, and bosh are lined with modified AL2O3-SiC-C refractories lining and fireclay and the hearth is lined with AL2C>3-SiC-C refractories lining, fireclay and castable insulation.
The main body portion of hot metal ladle is a covered with a fire clay insulation externally and internally lined with modified AL2O3-SiC-C refractories lining. The lining comprises a main body portion and the bottom portion of hardened refractory material, such as fire clay and further the bottom portion comprises of heavy insulation. The new types of AL2O3-SiC-C bricks are placed in top 7 rings and lower 5 rings. And AL2O3-SiC-C castable is placed in top 3 rings and spout. The use of 30% AL2O3 insulation brick was done in as safety lining to reduce heat loss and skull formation. And the Use of 40% AL2O3 high grog brick replacing conventional 38% AL2O3fireclay bricks in belly and bottom-lining.

10
The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive and any changes coming within the meaning and equivalency range of the appended claims are to be embraced therein.

11
We claim:
1. A method of developing AL2C>3-SiC-C refractories based lining liner structure
of predetermined shape for a hot metal transfer ladle to reduce mouth jam and
bottom build-up comprising the steps of: lining the hot metal transfer ladle with
AI2O3-SiC-C bricks and strong refractory material like fire clay.
2. A method as claimed in claimi, wherein AL2O3-SiC-C refractories are placed
in top 7 rings and lower 5 rings of the hot metal transfer ladle.
3. A method as claimed in claimi, wherein AL2O3-SiC-C castable is placed in
top 3 rings and spout.
4. A method as claimed in claimi, where in 30% AL2O3 insulation brick were
used as safety lining to reduce heat loss and skull formation.
5. A method as claimed in claimi, where in 40% AL2O3 high grog brick of
fireclay were used in belly and bottom lining.
6. A ladle for hot metal transfer comprising AL2O3-SiC-C refractories based
lining structure of predetermined shape to reduce mouth jam and bottom build
up.
7. A ladle for hot metal transfer as claimed in claim 6, wherein AL2O3-SiC-C
refractories are placed in top 7 rings and lower 5 rings of the ladle.
8. A ladle for hot metal transfer as claimed in claim 6, wherein AL2O3-SiC-C
castable is placed in top 3 rings and spout of the ladle.
9. A ladle for hot metal transfer as claimed in claim 6, wherein 30% AL2O3
insulation brick were used as safety lining to reduce heat loss and skull
formation.

12
10. A ladle for hot metal transfer as claimed in claim 6, where in 40% AL2O3 high grog brick of fireclay were used in belly and bottom lining.

To,
The Controller of Patents,
The Patent Office, Kolkata.

This invention relates to the development of AL2O3-SiC-C refractories based lining design for hot metal transfer ladle and ladle for hot metal transfer comprising AL2O3-SiC-C refractories based lining structure of predetermined shape to reduce mouth jam and bottom build-up. More specifically, it is concerned with the design of hot metal transfer ladle having lining of AL2O3-SiC-C bricks in mouth area and AL2O3-SiC-C castable in top ring and spout. The new lining design contributes for lesser mouth jam and bottom build-up for easy deskulling. The use of AI2O3-SiC-C refractories based lining reduced greatly the maintenance repairs, allowing lower cost, reducing men hour/power need, saving energy and refractory material, improving the availability and the safety for the operation.

Documents:

00200-kol-2007-correspondence-1.1.pdf

00200-kol-2007-form-26.pdf

0200-kol-2007-abstract.pdf

0200-kol-2007-claims.pdf

0200-kol-2007-correspondence others.pdf

0200-kol-2007-description (complete).pdf

0200-kol-2007-drawings.pdf

0200-kol-2007-form1.pdf

0200-kol-2007-form2.pdf

0200-kol-2007-form3.pdf

200-KOL-2007-(14-03-2012)-ABSTRACT.pdf

200-KOL-2007-(14-03-2012)-AMANDED CLAIMS.pdf

200-KOL-2007-(14-03-2012)-CORRESPONDENCE.pdf

200-KOL-2007-(14-03-2012)-DESCRIPTION (COMPLETE).pdf

200-KOL-2007-(14-03-2012)-DRAWINGS.pdf

200-KOL-2007-(14-03-2012)-FORM-1.pdf

200-KOL-2007-(14-03-2012)-FORM-13.pdf

200-KOL-2007-(14-03-2012)-FORM-2.pdf

200-KOL-2007-(14-03-2012)-OTHERS.pdf

200-KOL-2007-(18-10-2011)-ABSTRACT.pdf

200-KOL-2007-(18-10-2011)-AMANDED CLAIMS.pdf

200-KOL-2007-(18-10-2011)-DESCRIPTION (COMPLETE).pdf

200-KOL-2007-(18-10-2011)-DRAWINGS.pdf

200-KOL-2007-(18-10-2011)-EXAMINATION REPORT REPLY RECIEVED.pdf

200-KOL-2007-(18-10-2011)-FORM 1.pdf

200-KOL-2007-(18-10-2011)-FORM 2.pdf

200-KOL-2007-(18-10-2011)-OTHERS.pdf

200-KOL-2007-CORRESPONDENCE OTHERS-1.2.pdf

200-KOL-2007-CORRESPONDENCE.pdf

200-KOL-2007-EXAMINATION REPORT.pdf

200-KOL-2007-FORM 13.pdf

200-KOL-2007-FORM 18 1.1.pdf

200-kol-2007-form 18.pdf

200-KOL-2007-FORM 26 1.1.pdf

200-KOL-2007-FORM 26 1.2.pdf

200-KOL-2007-FORM 3.pdf

200-KOL-2007-GRANTED-ABSTRACT.pdf

200-KOL-2007-GRANTED-CLAIMS.pdf

200-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

200-KOL-2007-GRANTED-DRAWINGS.pdf

200-KOL-2007-GRANTED-FORM 1.pdf

200-KOL-2007-GRANTED-FORM 2.pdf

200-KOL-2007-GRANTED-SPECIFICATION.pdf

200-KOL-2007-OTHERS.pdf

200-KOL-2007-REPLY TO EXAMINATION REPORT.pdf

Abstract.jpg


Patent Number 253279
Indian Patent Application Number 200/KOL/2007
PG Journal Number 28/2012
Publication Date 13-Jul-2012
Grant Date 10-Jul-2012
Date of Filing 08-Feb-2007
Name of Patentee STEEL AUTHORITY OF INDIA LIMITED
Applicant Address RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 GARAI SWAPAN KUMAR RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
2 GHOSH NIRMAL KANTI RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
3 KUJUR MANISH KUMAR RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
4 CHINTAIAH PURIMETLA RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
5 DATTA PRABIR DURGAPUR STEEL PLANT, DURGAPUR-713203
6 SARKAR SUSANTA RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, P.O.: DORANDA, RANCHI-834002 STATE OF JHARKHAND, INDIA.
PCT International Classification Number C21C1/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA