Title of Invention

"A SIC BASED ALUMINOUS DRY CASTABLE FOR LINING BLAST FURNACE THROUGH/ RUNNERS AND A PROCESS FOR PRODUCING THE SAME"

Abstract A SiC based aluminous dry- castable composition for lining blast furnace troughs/runners, which castable possesses an extended performance life, is easily de-skullable and does not produce any fumes during its application to the troughs/runners of a blast furnace cast house, characterized in that the said castable is of the optimum composition by weight % : AI2O3-7I to 82, Fe2O3-0.6 to 1.0,SiO2-5to 10 SiC-11 to 15,Ca0-0.7to 1.2-andC-l to 2.
Full Text The present invention relates ,to a SiC based aluminous

dry castable for lining blast furnace troughs /runners and a process
for producing the same.
iC-C castable for use as a substitute of "the existing Alumina-
Carbon ramming mass used for lining blast furnace troughs/runners, which hajs a number of drawbacks, such as, a short perf ormance/hjOt metal throughout, not easily de-skullable due to penetration of
i -,:•••
metal and causing generation of fumes (during preheating of \ tills
troughs /runners, polluting the environment in the cast house, The object of the present invention, is to' provide? a
{. '
SiC based aluminous dry castable for lining blast furnace troughs/
runners, which has an extended performance life, can be 'easily
de-skulled increasing thereby the availability period of the
troughs /runners for the casting operation and does not produce
any fumes during heating in the cast hpuseThe typical composition and other particulars of the
existing alumina-carbon ramming mass are g'iven in Table I from which it is noted that the mass contains calcined bauxite as the basic ingredient and carbonaceous materials like pitch, tar and1 molasses as the binder and that the A12O3 content in the mass is low i.e. 57 to 67%, Pe2O3 content is 'high i.e. 3 to 49 and C content is very high i.e. 10 to 12%.
The existing ramming mass develops adequate bond?
strength and packing density only after ramming operations in the
troughs /runners to which it is applied, followed iby heating. Further more if the mass is applied to the troughs/runners at a
temperature exceeding 100°C the tar and pitch components of the
mass start melting and partial volatilizing causing generation of ftmes* Thereafter the polymerization of the hydrocarbons in the tar and pitch starts, and continues up to a temperature rise to 400°C, causing cross linking and strong carbon bonding among the calcined bauxite grains in the mass.
The typical composition and other particulars 'of the invested SiC based aluminous dry oast able are given in Table II, in which the fused alumina (A12O3) grain used as the basic ingredient of the castable is mixed with high alumina cement and microfines of alumina and silica, and the optimum composition of the castable, developed by carrying out extensive laboratory investigations and field trials, contains relatively a high proportion of Al20u i.e« 71 to 82#, a low proportion of Fc i.e» 0*6 to 1.C0i and a very low proportion of C i»e», 1 tp.
The chemical reaction takes place in the castable only during
* mixing of the dry castable with water 'of .quantity 4 Jto 5S£ of
the weight of the dry castable« Owing to the use of high" alumina jcement and microfines of alumina and silica as the binder] material
si. . • • ' * . .
jthe castable forms a thixotropic gel when mixed with water, which gel fills up the voids of the fused Al^t^ grains of the oast able with high curing strength at ambiant temperature* ; ^;,
Furthermore, the bonddag strength of the SiC based aluminous castable when mixed with water, increases steadily with rise in temperature above 800°C, because of the prior mullite formation in the castable at temperature below 800°C and subsequent recrystallisation in the castable with rise inC
I . ,
temperature of the castable above 800°Cj:and upto 1100?C,,,.

Thus the invention provides a SiC based aluminous

castable composition for lining blast furnace troughs/runners, which castable possesses an extended performance life, is easily de-skullable and does not produce any fumes during its application to. the troughs/runners1 of a blast furnace cast house, characterised in that the said castable/ls of the optimum composition by weight % : A1203 - 71 to 82, Pe205 - 0.6 to 1.0, Si02 - 5 to 10, SiC - 11 to 15, CaO - 0.7 to 1.2 and C - 1 to 2.
The invention alsoslgrovides a process for producing a

'SiC based aluminous dry castable composition lining blast furnace troughs/
:runners,- characterised in that the said process comprises the steps :
(a) charging fused alumina of grain size upto 6 mm and
alumina sand of grain size upto 1 mm in a mixer, and mixing the
ingredients therein thoroughly for at least 15 to 30 min;
(b) charging microfine powders of particle size 5 te 10
microns of alumina, silica, high alumina cement arid silicon carbide
in the said mixer in the required quantity for each said ingredient
and mixing the ingredients therein thoroughly for at least 15 to
30 min;
(c) charging powders of an exothermic metal such as A1/S1,
and of a graphitic carbonacious material such as pitch/graphite,
of particle size 5 to 10 microns, together with a deflocculating .
agent such as a phasphate in said mixer in required quantity and
mixing the ingredients charged in the mixer thoroughly for 15 to '
30 min,'the proportion of the ingredients charged into the mixer
in steps (a) to (c) being such as required for producing the
castable of the optimum composition (by weight %) of : Ai 0 -
71 to 82, Fe203 - 0.6 to 1.0, Si02 - 5 to 10, SiC - 11 to 15, CaO - 0.7 to 1.2 and C - 1 to 2.
' Unlike the invented castable, the existing alumina-carbon
ramming mass, being carbon bonded, attains moderate bond strength
with cement when heated moderately, without any further steady Increase in the bond strength of the mix with rise in the
temperature thereof.
The field trials have been conducted on the invented
qastable in a blast furnace cast house of 2-tonne capacity in

rocking runners, following the vibration casting technique. A
straight life throughput of 55,000 T has been obtained, which with minor repairs of the runners could be increased to 75,000 T, as against the throughput of only 6000 - 6500 T attainable by using the existing alumina-carbon ramming mass as the lining material of the runners.
The lining made of the invented castable" could be easily de-skulled with consequent increase in the cast house availability period. The generation of fumes in the cast house using the invented castable as the lining material of runners was found to be negligeble against the volume of fume generation baused by the existing alumina-carbon ramming mass used as liner for the runners.
i;
The techno-economic benefit attained by using the Invented castable in substitution of the existing alumina-carbon ramming mass is quite large.
Table I
Typical composition and other particulars of existing alumi!
Table Removed
B. Other Partioulaian
a) Grain size - Jo* to 4 mm
b) Bulk Density (B.D) (gms/cc) - 2.3 to 2.4
c) Apparent porosity (A.p.)(%) - 20 to 22
d) Crushing Strergth (kg/cm2) at 110°C - 80 to 100
e) Basic ingredient - Calcined Bauxite
t) Binder used - Carbonaceous (Tar/Pitch)
g) Nature of material - Rammable,
Table II
.tf i
Typical composition and other particulars of the Si6 based
Table Removed

B. Other Particulars;

a) Grain size of ingredients upto- 12 nun.
b) Bulk Density (B.D) at 1tO°C/24 hrs (g/cc) 5e
- 2'.85 to 3.:1 min.
c) Apparent porosity (A.p.)(%) - 12 to 16
2
d) Crushing Strength (kg/cm )
at 110°C/24 hrs - 300 to 400
at l400°C/3 hrs - 750 to 900
e) HMOR at 1400O)C,3 hrs. (kg/cm2) in - 65 to 90
oxidising atmosphere.

f) Permanent Liniar Change (PLC) - + 0,5
at 1400°C,2 hrs(%) -
g) Basic ingredient - Fused Alumina.
h) Binder used - High Alumina Cement and
Micrefines of Alumina and Silica.
i) Nature of material - Thlxotropic.

j) Water required for casting .;- 4 to 5%.






We Claim :-
1. A SiC based alutoinous castable for lining blast
furnace 'troughs/runners, which castable possesses at extended
performance life, is easily de-skullable and does not produce
•-\ -f .
any fumes during its application to the troughs/runners of a blast furnace cast house, characterised in that the said castable is of the optimum composition by v/eight % : A1203 - 71 to 82, Fe2O3 - 0.6 to 1.0, SiO2 - 5 to 10, SiC - 11 to 15, CaO - 0.7 to 1.2 and C - 1 to 2.
2. The castable as claimed in claim 1, which, when
mixed v/ith water of 4 to 5% by v/eight of the dry castable, is
capable of forming a thixotropic gel for binding the fused A120,
grains of the castable with high curing strength at ambient
temperature and still higher strength which steadily increases
with rising temperature above 800°C and upto 1100°C.
3. A SiC based aluminous castable for lining blast
furnace troughs/runners, substantially as herein described.
4. A process for producing a SiC based aluminous castable
for lining blast furnace troughs/runners, as claimed in claim 1,
characterised in that the said process comprises the steps:

(a) charging fused alumina of grain size upto 6 mm and
alumina sand of grain ;size upto 1 ,mm in a mixer, and mixing'the
ingredients therein thoroughly for at least 15 to 30 min;
(b) charging microfine powders•of particle size 5 to 10
microns, of alumina, silica, high alumina cement and silicon
carbide; in the said mixer in the required quantity for each

said ingredient and mixing the ingredients therein thoroughly
'|for at least 15 to 30 min
(c) charging powders of an exothermic metal such as Al/Si,

and of a graphitic carbonacious material such as pitch/graphite,
pf particle size 5 to 10 microns, together with a deflocculating agent such as a phasphate in said mixer in required quantity and mixing the ingredients charged in the mixer thoroughly for 15 to 30 min, the proportion of the ingredients charged into the mixer in steps (a) to (c) being such as required for producing the
pastable, of the optimum composition (by weight %} of : A1pO, -71 to 82, FepO,, - 0.6 to 1.0, SiOp - 5 to 10, SiC - 11 to 15,
-^ . ^~
iCaO - 0.7 to 1.2 and C - 1 to 2.
5. A process for producing a SiC based aluminous castable
for lining blast furnace troughs/runners, substantially as wherein described.

Documents:

2278-DEL-1995-Abstract.pdf

2278-del-1995-Claims.pdf

2278-del-1995-complete specifiction (granted).pdf

2278-del-1995-Correspondence-Others.pdf

2278-del-1995-Correspondence-PO.pdf

2278-DEl-1995-Description (Complete).pdf

2278-del-1995-Form-1.pdf

2278-del-1995-Form-2.pdf

2278-del-1995-gpa.pdf


Patent Number 193366
Indian Patent Application Number 2278/DEL/1995
PG Journal Number 29/2004
Publication Date 17-Jul-2004
Grant Date 30-Jan-2006
Date of Filing 11-Dec-1995
Name of Patentee STEEL AUTHORITY OF INDIA LIMITED
Applicant Address RESEARCH & DEVELOPEMENT CENTRE FOR IRON & STEEL, ISPAT BHAWAN LODHI ROAD, NEW DELHI-110002, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 SWAPAN KUMAR GARAI RDCIS , SAIL, P.O. HINOO, DORANDA, RANCHI-834002,
2 PURNIMETLA CHINTAIAH RDCIS , SAIL, P.O. HINOO, DORANDA, RANCHI-834002,
3 AJOY KUMAR DASGUPTA RDCIS , SAIL, P.O. HINOO, DORANDA, RANCHI-834002,
4 SWAPAN ROYCHOWDHURY RDCIS , SAIL, P.O. HINOO, DORANDA, RANCHI-834002,
5 PANKAJ KUMAR ROY CHOWDHURY RDCIS , SAIL, P.O. HINOO, DORANDA, RANCHI-834002,
PCT International Classification Number C04B 35/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA