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Патент USA US3086885

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lice
3,085,875
Patented Apr. 23,1963
2
REFRACTORY COM’PGSHTION AND PROCESS
3 986,87 6
plied in toto immediately after a- furnace is tapped and
cleaned and which ignites at the temperature of the fur
OF MAKING SAME
nace bottom to fuse in place to thus permit re-use of
the furnace within a brief time.
John Sliver Griggs, Olympia Fields, and William 1.. Ross,
Chicago, EL, and Alan R. Fraser, Michigan City, Ind, CR
Another ‘and further object of our invention is the
assignors to Garb-Rite 60., Chicago Heights, lit, a cor
provision of an exothermic mixture which because of
poration of Illinois
market conditions, freight rates, and the like, may the
No Drawing. Filed Dec. 5, 196%), Ser. No. 73,2334
prepared at a predetermined location and shipped to
12 Claims. (£5. ltl6—6i)
various ‘points for mixture with a base material such as
10
The present invention relates to an exothermic re
previously ?led application Serial No. 2,836, ?led January
18, 1960, which application was a continuation-in-part of
application Serial No. 770,606, ?led October 30, 1958,
both now abandoned, and more particularly, relates to
such composition which is useful in repairing basic-lined
steel-making furnaces such as open-hearths, Bessemer
converters, and the like. Our invention also relates to
the process of producing the instant refractory composi
tion.
It is'well known by those skilled in the steel-making
art that repair of an open-hearth furnace lining as now
‘generally practiced presents a time-consuming, expensive
problem, particularly since in ‘all presently-employed tech
niqnes a comparatively long “down-time,” in the order
of several hours, is required. In the operation of an open
hearth furnace, for example, after each ‘few melts (i.e.,
the operation from loading the furnace to tapping the
molten material therefrom), it becomes necessary to re
pair holes which are formed in either the furnace bottom
or the side walls thereof. With all presently known ma
terials such repairs are made while the furnace is un
charged, rand it has been necessary that the repair patch
the completely solidi?ed in place before the next charge
is loaded. In distinction to the usual repair mixes of the
prior art, the present invention is directed to an exo
thermic refractory mix which reduces furnace repair to
dolomite or magnesite in ?nely divided form and in the
proportions and manner of mixing as set forth herein to
be used on location or prepared for use on location where
the supply of base materials such as magnesite or dolo
fractory composition and is a continuation-impart of our
15
mite may be procured from adjacent localities where the
mixture is to be used, whereas, the shipment of the entire
mix, including the base material such as magnesite or
dolomite, because of freight rates or the like might be
prohibitive because of cost.
Other objects, features and advantages of our inven
tion will become apparent to those skilled in this particu
lar art from the following detailed disclosure thereof.
We have developed an exothermic refractory patching
material which consists essentiallyrof la blended mixture
of a ?nely-ground exothermic submixture such as ‘alumi
mm). and magnetite and a ?uxing halide material such
as sodium, potassium or calcium chloride or sodium,
potassium or calcium ?uoride in which crushed magnesite
and/or crushed magnesite and dolomite is added as a
body-producing mate-rial. The submixture provides the
exothermic feature of the present composition, whereas‘
the magnesite, crushed to 2. ~10 mesh particle size,
or the combination of a mixture of magnesite and dolo
mite, provides the main ceramic structural body, it of
course being understood that the submixture, after reac~
' tion, provides a portion of such repair structure.
EXOTHERMIC SUBMIXTURES
Table 1
a matter of only a few minutes with the consequent reduc
tion of down-time to result in considerable economic ad
vantage.
Material
In order to better understand our invention, reference
should ?rst be brie?y had to the construction of the lin
ings in open-hearth furnaces. Such linings are of a basic
refractory nature ranging in thickness from several ‘feet
on the furnace bottom to one foot or more on the side
Particle Percent Weight
Mesh Size
—100
6-20.
Iron oxide (F6304, F0zO3)____
Aluminum _______________________ .l _______ __
___.
—-200
18-40.
Calcium ?uoride_____
____
—100
Dolomite (Oalcined).
____
—20
Silicon _ _ _ _ _ . . _ _ _ _ _ . _ _
_ _ . . _ _ _ _ _ _ . _ _ ..
—100
. 25-9.
30-75.
3%
_
if desired.
walls and form the immediate container for the molten
metal and slag. Such lining must remain solid during
All percentages are by Weight, and 01' a particle size at least as small as
designated.
the operation of the furnace to not only contain the
charge, but likewise to provide a heat-insulation effect 50 An example of ‘speci?c exothermic submixture may be
vfor the various other furnace structural members and the
compounded within the limits of the following table:
furnace environment.
During operation the lining is
subjected to rather severe thermal and mechanical shocks
which result in varying degrees of erosion thereof to pro
duce cracks, holes, etc. In the past, because of the ex
pense, due to non~productive time primarily, the practice
‘has been to neglect repairing the minor cracks and holes
as they immediately form and to wait until a rather sub
stantial hole has ‘developed which must be repaired or
even more serious damage will result to the furnace. By
Table II
Material
Particle Percent
Mesh Size Weight
Aluminum ____________ __
.Iron oxide (Foam, Fe20a)
OaFz (?uorspar) _______ __
Dolomite (Oaloined)__
60 S111
n
' ‘co ______ .4. ___________________ _-
.
—100
12
—200
33
—100
5
—20
49
—100
1 0-3
the use of the present patching mix it now becomes eco
nomically feasible to repair such minor damage in its
13% silicon may be used if the refractory patch material as a whole
contains less than 3% silica.
initial stage ‘as a preventative maintenance procedure be
fore such cracks or openings become so large that major
This submixture is somewhat similar to Table I except
repairs are necessary, in addition to its usefulness in the 65 that
the percentages of the material are specific, although
repair of major deteriorational effects.
In view of the foregoing discussion a primary object
‘of our invention is to provide an exothermic refractory
not critical, with slight variations permitted with respect
to all of the materials.
'
We ?nd only a high level iron oxide is suitable to pro
mixture which is useful for the rapid repair of furnace
duce the desired results in the exothermic mixture as
lining materials.
.
70 set forth in all of the tables and that an iron oxide of
Another object of our invention is to provide an exo
thermic refractory patching material which may be ap—
type Fe2O3 will perform in this combination, but iron
oxide of the type F1230, is the more desirable form of
3,088,876
3
oxide for mom the combinations given and will produce
much more satisfactory results.
The calcium ?uoride is one of the ?ux materials used
and dolomite is the other. Sodium, potassium, calcium
chloride or sodium or potassium ?uoride may be used
with equal success as calcium ?uoride, all of these mate
rials being of the family of halides, and are mixed in the
same proportions, grain size, and manner as is the calcium
possible. While we prefer to progressively mix the mate
rials as outlined bereinabove, a proper mix can be pro
duced by simultaneously mixing together the materials
listed in the tables in the proportions speci?ed and of
the particle size speci?ed in Table II to secure a workable
mixture. If desired, however, instead of simultaneously
mixing all ‘the ingredients together, the proper proportion
ate quantities of aluminum powder and iron oxide can
?rst be mixed together in a tumbling machine so that the
?uoride in the combination of materials.
particles of aluminum powder are quite thoroughly coated
The complete refractory material is ‘formed by the 10 with the particles of iron oxide, and the mixtures thus ob
blending together of the exothermic material with crushed
taincd blended with the balance of the materials com
magnesite and/ or crushed magnesite and dolomite of
prising the composition, provided, this mixing is not too
quantities generally and particle size as given in the fol
violent and it is not conducted for too long a time so as to
lowing table:
remove the iron oxide particles from the aluminum par
Table III
ticles, although, in the quantities given there will be a
3 Percent
considerable quantity of iron oxide remaining to be dis
Aluminum powder, —- 100 mesh or smaller_____'__
2-8
tributed throughout the mass of material forming the total
Iron oxide, -—200 mesh (Fe3O4, Fe2O3) _______ ..-
6-15
Calcium ?uoride, -—100 mesh or smaller ______ __ 0.5-3
Dolomite 1 (calcined) ______________________ __ 15-60
Magnesite 2 (calcined) _____________________ __ 30-70
Silicon (optional) _________________________ __
0-1
1013 -—20 mesh particle size with the further proviso that
at least 60% be particles time enough to pass through a
mix.
The instant mixture is utilized in the dry state and
may either be directly applied into the hole to be repaired .
or ?rst bagged in conveniently combustible containers
which are then deposited in the repair site. Such repair
may be commenced immediately after the furnace has
been
tapped and cleaned, i.e., while it is still hot and
25
—100
screen.
2All mesh
particles
must be capable ‘of passage rthrough a —-10
within a few minutes after such application the repaired
mesh screen.
furnace is again ready for use.
_
3 All percentages ‘are by weight.
The materials comprising the present refractory re
pair composition have been carefully selected With their
An example of a complete refractory repair material
speci?c as to quantity and particle size mixed as herein
after described would be the addition of two parts crushed
magnesite to one part of the exothermic mixture of Table
II which would produce a mixture as follows:
Table IV
chemical and physical characteristics in mind. For ex~
ample, aluminum is a reducing agent and iron oxide is
.an oxidant, and by their combination in the foregoing
percentages, by ?rst mixing the aluminum with the iron
oxide there results a complete coating of the aluminum
.
1 Percent
35 particles by the iron oxide along with a considerable
surplus of oxidizing iron oxide. We prefer to use —-10()
Aluminum powder _________________________ __ 4.13
Iron oxide (Fe3O4, FeZO3) __________________ __ 11.00
mesh aluminum particles in order to provide a relatively
Calcium ?uoride ___________________________ __
large surface area for oxidation which in turn permits a
1.67
uniform exothermic reaction. Iron oxide (Fe3O4) is the
Dolomite (calcined) _______________________ __ 16.60
Magnesite (calcined) _______________________ __ 66.60 40 preferred oxide for use herewith because of its oxidizing
efficiency and the ease with which it adheres to the
1Again, in terms of weight percentages, and of the par
ticle size speci?ed in Table III.
aluminum particles.
'
Another suitable complete mixture and of a somewhat
As indicated above, in the preferred method of making
lower cost, would be a mixture as set forth in Table IV
our composition the calcium ?uoride, or ?uorspar, or
to which an equal part of dolomite is added which results 45 some other halide, which is the necessary ?uxing reagent
during the exothermic reaction, is next added to the
a complete mixture as follows:
aluminum
and iron oxide (preferably Fe3O4) mixture.
Table V
.The ?uorspar, or ?uxing halide, coats both the free or
1 Percent
excess iron oxide and also the iron oxide surrounding the
Aluminum powder _______________ -., _______ __
2.065
Iron oxide (Fe3O4, Fe2O3) _________________ __
5.50‘
Calcium ?uoride _________________________ __
.835
Dolomite (calcined) ______________________ __ 58.30
50
aluminum powder during the blending operations. Such
intimate contact greatly improves the ?uxing problem.
The calcined dolomite is critical to the successful use
of our composition since it provides the uniform supply
Magnesite (calcined) _________ .., ___________ __ 33.30
of the oxides of magnesium and calcium to the reacting
1Again, in terms of weight percentages, and of the par
55 components which is necessary for a good slag forma
ticle size speci?ed in Table III.
tion whereas the magnesite is utilized for initial reaction
In preparing the foregoing mixtures we prefer to ?rst
with such super heated slag to permit the formation of
form the submix-ture by mixing the aluminum powder with
a homogenous basic refractory. Particle size distribution
the iron oxide thereby thoroughly coating the aluminum
of both is controlled to minimize the porosity of the re
particles with the iron oxide and thereafter progressively 60, pair
patch and to assist in the proper chemical reaction.
adding the calcium ?uoride and calcined dolomite in this
The optional silicon added to the patch material as
order. ‘Following this, the magnesite is blended with the
snbmixture to form. the instant exothermic repair mix.
If preferred, additional dolomite may be added to the ex
othermic mixture and then the required magnesite may
‘a whole increases the acidity of the slag considered above.
Such silicon also reacts exothermically to form silica and
thus additionally contributes to the heat generated by
be added to the mixture thus formed. As an alternative, 65 the instant exothermic mix. A suitable high silicon alloy
may be used instead of the metallic silicon, but as indi
the required quantity of dolomite and magnesite may be
premixed and this mixture blended into the exothermic
mixture to form a completed product.
In the blending operation it is preferred that the appa
cated above, if the patch material already contains more
than 3% silica, such addition is unnecessary.
The present mixture ignites at about 2000° F., and
ratus used will produce a tumbling action of the material 70 following ignition the exothermic reaction proceeds to
and that its abrasiveness upon the mixture be held to a
completion in stages through the repair material in ac
minimum for his ‘extremely desirable that the mixture
cordance with the following chemical reaction:
be welleblended and the particles thereof be in intimate
contact to assure complete chemical reaction; on the other
8
F3304“)
F6
be as little disrupted as 75
hand, the particle sizes should
3,086,876
.
5
to yield a homogenous repair patch. This reaction causes
the formation of an unstable slag on the reacting inter
face of the mixture. The unstable slag thus formed is
in a molten state and has been pre?uxed by the Cal-"2
in the mixture causing the immediate absorption unto
itself of the entrained dolomite ?nes producing a low
magnesium oxide unstable liquid slag having a tempera
ture in excess of 3000° R, which liquid unstable slag
immediately attacks the magnesite ?nes, and is thereupon
bonding and may be used to ?ll _a hole of any depth and
size without additional furnace ?ring to insure bonding.
Another desirable advantage of the use of our material
is that it can be used after any heat has been tapped and
the furnace “blown out” to repair inner cracks and small
openings which may develop in the furnace bottom be
fore such cracks or openings become of major concern
and thus keep a furnace in operation by such maintenance
for long periods of time whereas the usual practice is not
transformed into a stable basic slag which coats and
adheres to the magnesite grains, thereby e?ecting a basic 10 to attempt repair of such small damage until greater dam
age results from furnace operations and then discontinue
to basic bond between the magnesite grains and the slag
the furnace operations for a major repair job resulting in
matrix. The composition then solidi?es into a homoge
- greater expense and longer periods of non-production for
nous refractory mass which has an overall refractoriness
a furnace.
in excess of the temperature requirements of an open—
15
Not only can the instant composition be used to repair
hearth furnace bottom, and consisting of partially dif
monolithic furnace linings, but it will be readily apparent
fused grain magnesite completely entrained in a matrix
to those skilled in this art that it can likewise ‘be used to
of dolomitic slag. The bonding slag thus formed by the
bond refractories, such as ?re bricks and ram materials
unstable slag and the magnesite ?nes combined with the
and in other applications where the magnesite bond may
exothermic heat generated by the material, bonds the
patch to the surrounding portion of the furnace bottom 20 be highly advantageous and that the temperatures pro
duced are never high enough to cause damage to any part
thus producing a hom-ogenous patched area of the fur
of the furnace in which the mixture is being used.
nace bottom. Open-hearth usage, that is the application
It will be understood that variations and modi?cations
of steel making temperatures coupled with the pressure
of the molten steel bath in the furnace, may further com 25 may be effected without departing from the spirit or scope
of the novel concepts of the instant invention.
plete the diffusion process between the grains of mag
What is claimed is:
nesite and the matrix whereby both lose their identities,
1. A refractory composition consisting essentially of an
but this step only increases the already high refractoriness
intimate mixture of the following materials in ?nely di
throughout and particularly at patch bottom interface
vided particle size in percentages by weight:
and assists in producing suitable corrosion resistance.
Such elevated temperature, i.e., greater than 2600° F.
Percent
Aluminum _____________________________ __
2-8
likewise causes a diffusion of Fe2O3 formed by re-oxida
Iron oxide ______________________________ __
6-15
tion of the minimiscule particles of metallic iron in the
A halide ?ux forming material _____________ __ 0.5-3
presence of super heated ‘air through the repair patch
to the patch-refractory wall boundary to result in a further 35 Dolomite (calcined) ______________________ __ 10-25
increase in strength not only throughout the patch, but
Magnesite (calcined) _____________________ __ 50-80
also at the patch-wall interface.
Referring to the process in somewhat greater detail,
it should be understood that during the exothermic com~
2. The refractory composition as de?ned by claim 1
wherein up to 1% silicon is added.
3. An exothermic submixture for use in a refractory
bustion process and particularly, during the reaction be
tween the aluminum powder and the iron oxide consider
able exothermic heat is generated in the area immediately
between adjacent magnesite particles and that the tem
perature may range above 3000° F. Such heat permits
the individual magnesite grains to react with the unstable
mix consisting of the following materials in ?ne particle
form in percentages by weight:
Percent
Aluminum ________________________________ __
Iron oxide ________________________________ .__
12
'33
CaF2 (?uorspar) ___________________________ __ .5-5
slag to provide the bonding mechanism ?rst between such 45 Dolomite _________________________________ __ 50
grains on one hand, ‘and it is such heat and resultant
effects that permit the adherence of the repair patch to
the surrounding furnace lining. Such aforesaid tempera—
4. The exothermic submixture as de?ned by claim 3
in which up to 3% powdered silicon is added.
5. An exothermic refractory material as follows:
ture of above 3000° F. occurs substantially only in the
minute areas surrounding each magnesite grain rather 50
Percent
than throughout the entire patch and that therefore the
Aluminum powder, —100 mesh _____________ _..
2-8
average temperature of the reacting patch may be only
Iron oxide (Fe3O4, Fe2O3), ——200 mesh ______ _.. 6-15
slightly above 2000" F.
A halide ?ux producing material, —100 mesh___._ .5-3
Dolomite (calcined of —20 mesh particle size
It should further be understood that in the practice of
55
the present invention the materials forming the exother
with 60% particles of —100 mesh) _______ __ 15-60
mic mix are so selected as to not ignite until the mixture
Magnesite (calcined), -10 mesh ____________ __ 30-70
has been heated to a temperature of approximately 2000°
6. The exothermic mixture as de?ned in claim 5 to
F. It is critical that the exothermic reaction of the alumi
which 1% silicon is added.
num be restrained until the surroundings thereof reach 60
7. An exothermic refractory material as follows:
about 2000° F. since the resultant slag will not wet the
magnesite particles at temperatures much lower than this.
By using the instant composition it is possible to prevent
Aluminum powder _________________________ __
chain exothermic reactions from taking place instanta
Iron oxide (Fe3O4, r6203) _________________ __ 11.00
Percent
4.13
neously throughout the entire mass since the mass is 65 Calcium ?uoride __________________________ __ 1.67
Dolomite (calcined) _______________________ __ 16.60
heated to the critical temperature in depth stages and thus
the exothermic action occurs only as its surrounding
mass reaches the critical temperature from the heat gen
erated in an adjoining mass area.
Magnesite (calcined) ______________________ _.. 66.60
8. An exothermic refractory material as follows:
By the use of the foregoing composition it is possible 70
Percent
Aluminum power _________________________ __ 4.13
to considerably reduce the time required in patching fur
Iron oxide (Fe3O4, Fe2O3) __________________ __ 11.00
nace linings not only because of the rapid setting but fur
ther because it may be used dry and requires no further
preparation. In addition, such patching material is self
A ?ux producing halide ____________________ __ 1.67
Dolomite (calcined) _______________________ __ 16.60
75 Magnesite (calcined) ______________________ __ 66.60‘
3,086,876
9. An exothermic refractory material in ?nely divided
particle size as follows:
Percent
Aluminum ______________________________ __
2.06
Iron oxide _______________________________ __
Calcium ?uoride _________________________ __
5.50
.835
3
composition which consists in progressively blending to
gether a mixture of 4% powdered aluminum, 10% iron
oxide in ?nely divided form, 2% calcium ?uoride, 17%
dolomite of -——20 mesh screen size with at least 60% of
the dolomite of a —»100 mesh screen size, and 67%
magnesite of ‘—lO mesh screen size.
12. A method of making an exothermic refractory
composition which consists in progressively blending to
gether in approximate quantities by Weight of 4.13 percent
10. The method of making an exothermic refractory 10 powdered aluminum, 11 percent iron oxide in ?nely di
Dolomite (calcined) ______________________ __ 58.30
Magnesite (calcined) ______________________ __ 33.30
composition comprising the making of a submixture by
the progressive blending ?rst of powered aluminum and
iron oxide in the approximate proportions of a 12%
aluminum and 33% iron oxide until the aluminum par
vided form, 1.67 percent a halide ?ux producing material,
and 16.60 percent calcined dolomite of —20 mesh screen
size with at least 60 percent of the dolomite of a -—-100
mesh screen size and 66.60 percent calcined magnesite of
ticles are coated with iron oxide, blending a halide ?ux 15 a —10 mesh screen size and adding to the mixture thus
formed an equal quantity of calcined dolomite of the
forming material in 3% proportion of the total submix
screen sizes hereinbefore set forth.
ture with the aluminum ‘and iron oxide mixture, blending
substantially an equal amount of calcined dolomite to
References Cited in the ?le of this patent
form the complete submixture and thereafter blending
20
UNITED STATES PATENTS
magnesite in the mixture thus formed in quantity at least
equal to the submixture and up to 80% of the complete
1,934,263
' Hacks et al ____________ __ Nov. 7, 1933
refractory mixture.
7
>
11. The method of making an exothermic refractory
2,253,955
Hebbe et al ___________ .... Aug. 26, 1941
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