U.S. patent number RE31,589 [Application Number 05/786,037] was granted by the patent office on 1984-05-22 for thermal insulation molten metal.
This patent grant is currently assigned to Foseco Trading A.G.. Invention is credited to Edward J. Jago, Richard C. Phoenix.
United States Patent |
RE31,589 |
Phoenix , et al. |
May 22, 1984 |
Thermal insulation molten metal
Abstract
There is disclosed a material and method for preventing heat
loss from molten metal, one side of this material being impregnated
with heat insulating refractory or exothermic material. The
impregnated side has a porosity of less than about 50 AFS units and
contains a binder.
Inventors: |
Phoenix; Richard C. (Lakewood,
OH), Jago; Edward J. (Berea, OH) |
Assignee: |
Foseco Trading A.G. (Chur,
CH)
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Family
ID: |
27397673 |
Appl.
No.: |
05/786,037 |
Filed: |
April 8, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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851745 |
Aug 20, 1969 |
|
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Reissue of: |
226933 |
Feb 16, 1972 |
03876420 |
Apr 8, 1975 |
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Current U.S.
Class: |
75/709;
106/38.22; 149/14; 164/123; 75/304; 75/959 |
Current CPC
Class: |
B22D
7/10 (20130101); B22D 7/102 (20130101); B22D
41/00 (20130101); C21B 7/14 (20130101); F27B
3/10 (20130101); B22D 41/02 (20130101); F27D
1/0009 (20130101); F27B 2014/0893 (20130101) |
Current International
Class: |
B22D
41/00 (20060101); B22D 7/10 (20060101); B22D
41/02 (20060101); B22D 7/00 (20060101); C21B
7/14 (20060101); F27B 3/10 (20060101); F27D
1/00 (20060101); F27B 14/00 (20060101); F27B
14/08 (20060101); C21B 015/02 (); B22D
007/00 () |
Field of
Search: |
;75/27,96 ;106/38.22
;149/37 ;164/123 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Walsh; Donald P.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of my application Ser. No.
851,745, filed Aug. 20, 1969 and now abandoned.
Claims
We claim as our invention:
1. A material for minimizing heat loss from the exposed surfaces of
molten metal comprising a preformed and self-supporting fibrous mat
in sheet form which may be handled without disintegrating and which
may be cut to size prior to the application of said preformed and
self-supporting mat to the exposed surfaces of molten metal having
an inner metal facing surface and an outer exposed surface, with
only the metal facing surface of said mat being impregnated with a
material selected from the group consisting of heat insulating
refractory materials and exothermic materials, and containing a
binding agent to bind said material to the fibers of the metal
facing surface of said preformed and self-supporting fibrous mat,
said impregnated metal facing surface having an average porosity of
less than about 50 AFS.
2. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 1 which is impregnated on the metal
facing surface of said fibrous mat with a heat insulating
refractory material selected from the class consisting of finely
divided sand, silica flour, silimanite, grog, zirconia, burned
dolomite, refractory silicates, alumina, magnesia, sircon flour and
chromote flour.
3. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 2 wherein at least 50 percent by
weight of the finely divided material passes a 200 BSS mesh.
4. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 1 wherein the metal facing surface
of said mat is impregnated with an exothermic material consisting
essentially of finely divided oxidisable material and an oxidising
agent therefor.
5. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 4 wherein the finely divided
oxidisable material is selected from the class consisting of
particulate aluminum, calcium silicide and ball mill dusts, at
least 5 percent by weight of which passes a 200 BSS sieve.
6. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 4 wherein the oxidising agent is
selected from the class consisting of alkali metal and ammonium
nitrates, chlorates and perchlorates, iron oxide and manganese
dioxide.
7. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 1 wherein the fibre of said fibrous
mat is a refractory fibre selected from the class consisting of
aluminum silicate, calcium silicate and metal fibres.
8. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 1 wherein the fibre of said fibrous
mat is an organic fibre selected from the class consisting of
cotton, jute and acrylonitrile fibres.
9. A material for minimizing heat loss from the exposed surfaces of
molten metal according to claim 1 wherein the binding agent is
selected from the class consisting of natural and synthetic gums
and resins, alkali metal silicates, sulphite lye, colloidal silica
and aluminum phosphates.
10. A material for minimizing loss from the exposed surfaces of
molten metal according to claim 1 wherein the total thickness of
said fibrous mat is between about 6 and about 150 mm thick, and
wherein the impregnation of the metal facing surface extends to a
depth of between about 1 and about 50 mm.
11. A material for minimizing heat loss from the exposed surfaces
of molten metal according to claim 1 wherein the total thickness of
said fibrous mat is between about 12 and about 50 mm thick, and
wherein the impregnation of the metal facing surface extends to a
depth of between about 6 and about 25 mm.
12. A material for minimizing heat loss from the exposed surfaces
of molten metal according to claim 1 which is faced with a layer,
on the impregnated metal facing surface of said mat, selected from
the class consisting of heat insulating refractory materials and
exothermic materials.
13. A material for minimizing heat loss from the exposed surfaces
of molten metal according to claim 12 wherein said facing layer is
less than about 25 mm thick and has a density of between about 0.2
and about 1.5 mm/cc.
14. A material for minimizing heat loss from the exposed surfaces
of molten metal according to claim 12 wherein said fibrous mat is
reinforced by a metal mesh of grid.
15. A process for minimizing heat loss from the exposed surfaces of
molten metal which comprises applying to said exposed metal
surfaces a fibrous mat having only one of its surfaces impregnated
with a material selected from the group consisting of heat
insulating refractory materials and exothermic materials, and a
binding agent to bind said impregnating material to the fibers of
the impregnated surface of said mat, so that the impregnated
surface of said fibrous mat is adjacent to and covers the exposed
metal surfaces, said impregnated surface having an average porosity
of less than about 50 AFS.
16. The process of claim 15 wherein the impregnated surface of the
fibrous mat applied to the exposed surfaces of molten metal is
impregnated with a heat insulating refractory material selected
from the class consisting of finely divided sand, silica flour,
sillimanite, grog, zirconia, burned dolomite, refractory silicates,
alumina, magnesia, sircon flour and chromote flour.
17. The process of claim 15 wherein the impregnated surface of the
fibrous mat applied to the exposed surfaces of molten metal is
impregnated with an exothermic material consisting essentially of
finely divided oxidisable material and an oxidising agent
therefor.
18. The process of claim 15 wherein the fibre of the fibrous mat
applied to the exposed surfaces of molten metal is a refractory
fibre selected from the class consisting of aluminum silicate,
calcium silicate and metal fibres.
19. The process of claim 15 wherein the fibre of the fibrous mat
applied to the exposed surfaces of molten metal is an organic fibre
selected from the class consisting of cotton, jute, and
acrylonitrile fibres.
20. The process of claim 15 wherein the binding agent used to bind
the impregnating material to the fibers of the impregnated surface
of the fibrous mat applied to the exposed surfaces of molten metal
is selected from the class consisting of natural and synthetic gums
and resins, alkali metal silicates, sulphite lye, colloidal silica
and aluminum phosphates.
21. The process of claim 15 wherein the total thickness of the
fibrous mat applied to the exposed surfaces of molten metal is
between about 6 and about 150 mm, and wherein the impregnation of
the impregnated surface extends to a depth of between about 1 and
about 50 mm.
22. The combination comprising an exposed surface of molten metal
and a material for minimizing heat loss from said exposed molten
metal surfaces which comprises a preformed fibrous mat in sheet
form having an inner metal facing surface which is adjacent to and
covers said exposed molten metal surfaces and an outer exposed
surface, with only the metal facing surface of said mat being
impregnated with a material selected from the group consisting of
heat insulating refractory materials and exothermic materials, and
containing a binding agent to bind said material to the fibers of
the metal facing surface of said fibrous mat, said impregnated
metal facing surface having an average porosity of less than about
50 AFS. .Iadd. 23. In a shaped heat article for forming a
molten-metal contacting lining for metallurgical moulds or the like
which comprises a refractory composite consisting essentially of an
inorganic fibrous refractory material and a granular refractory
filler material, an exothermic mixture of a fuel and an oxidising
agent, and a binder, the improvement wherein said fibrous
refractory material is a material selected from aluminosilicate
fibres and said shaped article has a density of about 0.2 to 1.5
grams per cubic centimeter. .Iaddend..Iadd. 24. A shaped heat
insulating article according to claim 23 comprising a fluoride
catalyst for the exothermic mixture. .Iaddend..Iadd. 25. A shaped
heat insulating article according to claim 24 wherein the fluoride
catalyst is cryolite. .Iaddend..Iadd. 26. The article defined in
claim 23, wherein said granular material is one or more materials
selected from the group consisting essentially of alumina,
magnesia, chromite and zirconia. .Iaddend. .Iadd. 27. The article
defined in claim 23, wherein the fuel is one or more materials
selected from the group consisting essentially of aluminum and
magnesium powders. .Iaddend..Iadd. 28. The article defined in claim
27, wherein the oxidising agent is one or more materials selected
from the group consisting essentially of iron oxide or manganese
dioxide. .Iaddend..Iadd. 29. In a shaped heat insulating article
for forming a molten-metal contacting lining for metallurgical
moulds or the like which comprises a refractory composite
consisting essentially of an inorganic fibrous refractory material
and a granular refractory filler material, an exotheric mixture of
a fuel and an oxidising agent, and a binder, the improvement
wherein said fibrous refractory material is a material selected
from aluminosilicate fibres and said shaped article has a density
of about 0.48 grams per cubic centimeter. .Iaddend. .Iadd. 30. In a
shaped heat insulating article for forming a molten-metal
contacting lining for metallurgical moulds or the like which
comprises a refractory composite consisting essentially of an
inorganic fibrous refractory material and a granular refractory
filler material, an exothermic mixture of a fuel and an oxidising
agent, and a binder, the improvement wherein said fibrous
refractory material is a material selected from aluminosilicate
fibres and said shaped article has a density of up to 0.5 grams per
cubic centimeter.
Description
BACKGROUND OF THE INVENTION
The present invention relates to the thermal insulation of molten
metal.
In many cases in the foundry and steel making industries it is
desired to minimize the loss of heat from bodies of molten
metal--for example in ladles and tundishes, or in the heads of
solidifying ingots, or in the risers of castings.
It is customary to line the sides of ingot moulds, casting risers,
ladles and tundishes with a layer of heat insulating material.
However, the maximum insulation attainable by this method is often
considered insufficient, and methods have therefore been proposed
to minimize the heat loss from the horizontal molten metal
surface.
Such methods include the provision of a moulded insulating cover
(for example of plaster, clay, fire-brick) or of a layer of
powdered heat insulating material (for example rice husks). In
addition, it may be desirable positively to supply heat to the
molten metal and the use of an exothermic composition has been
proposed and employed. A further known procedure is to place on the
molten metal surface a mixture of loose powdered exothermic
material and loose powdered heat insulating material contained in a
cardboard or like container to ease handling. However, these
procedures have proved to be unsatisfactory because of the high
inclusion levels of these loose powdered materials in the surface
of the solidified metals. Further, as can be appreciated the loose
powdered materials, because they must be shipped and stored in
containers which may spill or leak, are often difficult to handle
and often lead to an unevenness in the level of application with a
consequent unevenness in the heat insulating properties of the
insulative coating.
It is, therefore, an object of the present invention to provide a
heat insulating material which when applied to the exposed surfaces
of molten metal affords covering for the surface of the molten
metal and a low inclusion level of the insulation material in the
solidified molten metal.
It is also an object of the invention to provide a heat insulating
material for application to the exposed surfaces of molten metal
which is self-supporting and, therefore, easy to handle, ship,
store and apply.
DESCRIPTION OF THE INVENTION
According to the present invention there is provided a material for
minimizing heat loss from the exposed surfaces of molten metal
bodies which comprises a preformed fibrous mat in sheet form having
an inner metal facing surface and an outer exposed surface, with
only the metal facing surface of the mat being impregnated with a
material selected from the group consisting of heat insulating
refractory materials and exothermic materials, and containing a
binding agent to bind these materials to the fibers of the metal
facing surface of the fibrous mat and with this metal facing
surface having a porosity of less than about 50 AFS units.
The insulating material of the present invention because it is
self-supporting (that is, a discrete substance which may be handled
without disintegrating) may be preformed into large sheets and then
cut to the desired size (as for example, by sawing) just prior to
use. In use the insulating material of the present invention is
laid upon the exposed surface of the molten metal with the inner
metal facing impregnated surface downwards. This impregnated
surface provides a refractory facing which covers the molten metal
surface and minimizes heat loss from the molten metal body by
radiation. The outer exposed surface of unimpregnated fibre is
highly thermally insulative.
The fibrous mat may be made from refractory fibrous material, for
example, asbestos, slag and mineral woods, aluminum silicate
fibres, calcium silicate fibres, and metal fibres, or it may be
made of organic fibrous material such as cotton, jute,
acrylonitrile, and other cellulosic or synthetic organic polymeric
fibres of mixtures thereof. In addition, carbonized fibres, e.g.,
carbonized acrylonitrile fibres may also be employed.
The refractory heat insulating impregnating material is preferably
a finely divided refractory (preferably at least 20 percent by
weight passing a 200 BSS mesh, more preferably at least 50 percent
by weight passing a 200 BSS mesh) such as sand, silica flour,
sillimanite, grog, zirconia, burned dolomite, refractory silicate,
alumina, magnesia, zircon flour, chromite flour.
While most any exothermic materials may be employed to impregnate
the metal facing surface of this fibrous mat, however, it is
preferred to use an exothermic of the type employing a finely
divided (preferably at least 5 percent by weight passing a 200 BSS
mesh) oxidizable material such as aluminum calcium silicide,
magnesium or ball mill dust, and an oxidising agent therefor, for
example an alkali metal or ammonium nitrate, chlorate or
perchlorate, or iron oxide (haematite, millscale) or manganese
dioxide.
The binding agent used to bind either or both of the refractory or
exothermic materials to the fibers of the metal facing surface of
the fibrous mat may be any of those normally used in the foundry
materials art, as for example, natural or synthetic gums or resins,
(phenol and ureaformaldehyde, furane), alkali metal silicates,
sulphite lye, colloidal silica, aluminum phosphates. The total
thickness of the fibrous mat is preferably between about 6 and
about 150 mm, more preferably between about 12 and about 50 mm, the
thickness of the impregnated portion of the fibrous mat ranges
correspondingly preferably between about 1 and about 50 mm, more
preferably between about 6 and about 25 mm.
The density of the fibrous mat before the impregnation is
preferably in the range of about 0.008 and about 0.65 gm/cc, more
preferably between about 0.03 and about 0.3 gm/cc, while that of
the impregnated portion is correspondingly preferably in the range
of between about 0.03 and about 1.5 gm/cc, more preferably in the
range of between about 0.05 and about 1.0 gm/cc.
If desired, the fibrous mat may be faced with a layer, adjacent to
the impregnated metal facing surface, of heat insulating refractory
material or exothermic material. Such a facing layer may be formed
of any of the heat-insulating refractory materials and exothermic
materials, with binding agents, all as noted above for the
production of the impregnated layer. The thickness of such a facing
layer is preferably less than about 50 mm, more preferably less
than about 25 mm, and its density is preferably between about 0.1
and about 2.2 gm/cc, more preferably about 0.2 and about 1.5
gm/cc.
If desired, in order to enhance the self-supporting characteristics
of the insulating material of the invention, a metal grid or mesh
or other reinforcing element may be incorporated into the fibrous
mat either during manufacture or by any other convenient method.
Where the material has a facing layer of refractory heat insulating
or exothermic material, the mesh may be situated between such
facing layer and the fibrous mat.
The materials of the present invention may be formed by any
convenient method, but the preferred technique is to form a slurry,
preferably aqueous, of the constituents of the impregnant and of
the binder, place the fibrous mat on a mesh support, bring the
slurry onto the mat and, by the application of pressure or suction,
force the liquid medium of the slurry through the fibrous mat and
away, leaving the slurry solids impregnating the upper portion of
the mat, and if desired, constituting a layer thereover. The
resultant damp slabs may then be stoved to drive off remaining
slurry medium (usually water) after which the slab is ready for
use.
The following examples will serve to illustrate the novel
insulating material of the invention and several methods by which
it may be made. These examples are not, however, intended as
limitations upon the scope of the invention.
EXAMPLE 1
50 grams of slag wool was dispersed in 800 grams of water and
formed to shape on a 60 mesh screen using 20 p.s.i. air pressure. A
slurry was made of 50 grams of a commercial exothermic hot topping
compound (sold under the Registered Trade Mark FERRUX 107) and 2
grams of phenolic resin powder in 200 grams of water and the
mixture filtered through the slag wool pad using 20 p.s.i.
pressure. The duplex pad formed was dried at 200.degree. C. for 2
hours. A good bond existed between the two layers. The exothermic
layer exhibited some friability and the slag wool layer was very
soft.
EXAMPLE 2
50 grams of slag wool was dispersed in 800 grams of water and
formed to shape on a 60 mesh screen using 20 p.s.i. air pressure. A
slurry was made of 45 grams of the exothermic hot topping compound
noted in Example 1, 2 grams of phenolic resin, and 5 grams slag
wool in 300 grams of water. The mixture was filtered through the
slag wool pad using 20 p.s.i. air pressure. The duplex pad was
dried at 200.degree. C. for 2 hours. A good bond existed between
the two layers. The exothermic layer was of good quality, but the
slag wool layer was soft.
EXAMPLE 3
Example 2 was repeated with the addition of 4 percent of phenolic
resin to the slag wool before slurrying. The duplex pad was of good
quality both layers being strong.
EXAMPLE 4
456 grams of slag wool and 18 grams of phenolic resin powder was
slurried in 10,800 grams of water, and filtered through a 60 mesh
screen using a 28 inch vacuum to suck the material through the
screen. 900 grams of the commercial exothermic hot topping compound
noted in Example 1 and 36 grams of phenolic resin powder was
slurried in 5,400 grams of water and filtered through the slag wool
pad. After drying, the duplex slab weighed 521 grams and was 15 mm
thick. Overall density of the slab was 0.63 gm/cc.
Heat flow tests indicated that at 1,410.degree. C. total quantity
of heat transmitted through the specimen amounted to 10.250
joules/cm.sup.2, from 0 to 60 minutes.
EXAMPLE 5
200 grams of papers, 750 grams of slag wool and 50 grams of
phenolic resin powder were slurried and filtered using a 28 inch
vacuum to suck the material through a 60 mesh screen. 900 grams of
an Exothermic Hot Topping Compound mix (of, by weight 2 percent
sodium nitrate, 2 percent sodium cryolite, 10 percent red iron
oxide, 86 percent ball mill dust) was slurried in water together
with 50 grams phenolic resin powder, and 50 grams of slag wool.
This mixture was filtered through the slag wool layer. Total
thickness of the pad was 36 mm of which 9 mm was exothermic and 27
mm slag wool. Average density of the duplex pad was 0.48 gm/cc.
Density of the insulator portion was determined as 0.3 gm/cc. and
that of the exothermic 1.28 gm/cc. Total heat transferred through
the duplex at 1,410.degree. C. was determined at 9100
joules/cm.sup.2 for 0 to 60 minutes.
* * * * *