Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
Technical ~ield:
-
This invention relates to the transfer and pouring of
molten metals such as the pouring of molten iron and steel
~rom a refractory lined bottom pour transfer ladle and the
practice o~ providing a ladle covering compound -from heat
insulation and adsorp~ion of non-metallics from the molten
metal in the ladle.
Description of the Prior Art:
The prior art compounds used in covering molten metals
may be seen in U.S. Patents 3,516,821 o~ June 23, 1~70 to
Neu, 3,607,234 of Sept. 21, 1971 to Kawawa, et al, 3,630,267
of Dec. 28, 1971 to Hlinka, et al, 4,119,468 of Oct. 10, 1978
to Wiley, 4,066,446 of Jan. 3, 1978 to Peck, and 4,261,750
of April 14, 1981 to ~oster. Similar disclosures may be
seen in U.S.S.R. Pàtent 262,923 of Nov. 9, 1970 and Poland
Patent No. 47350 of Augus-t 11, 1969. The materials used --
in-the compounds disclosed in these patents vary :Erom the
gas genera-ting granules of carbon black and chalk and a
wetting agent o~ Patent 3,516,821, the Portland cement,
fluorspar, Chamotte powder, soda ash and coke breeze of ---
U.S. Patent 3,607,234 , the bloatèd (expanded) fire clay
of Patent 4,066,446, the lron ore, iron oxide, sodium nitrate,
lime, sand and ~ine~y divided aluminum of Patent 4,119,468,
the vermiculite or perlite ore and a minimum of acid treated
graphite o~ Patent 4,261,750 to the slag forming substances
o~ the U.S.S.R. and Poland patents which are essentially
28 Portland cement, fluorite, soda and ~`eldspar.
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Summary of tlle Invention
. _
An expanding ladle covering compound for application
to ferrous`and non-ferrous molten me-tals is principally
formed from predetermined amoun-ts of burn-t lime, aluminum
dross, fluorspar and acid -treated graphi-te. Aluminum, clays.
grog, lsyanite, dolomite, perlite, vermiculite, and
diatomaceous earth may be used in place of the alumlnum
dross. The acid treated graphite may be replaced ~y
perlite ore, mica ore, sodium silicate. Baking soda and
crystal ammonia flour may be incorporated in the compound
in known amounts to improve the desired expansion volume.
The compound forms a virgin instant slag with predetermined
absorption abilities enabling it -to retain elements coming
incorporation of exothermic compounds such as disclosed
in Patent 4,261,750 and Patent 3,630,267 discloses the
application of a layer of molten slag of a specified
thickness to the molten me-tal in the ladle.
The present invention provides a compound which
in con-tact with molten metal as an insulating ladle
cover, possesses unusual controllable expansion character-
istics resulting in an expanded ladle covering that is
unusually ef~ective in absorbing non-metallic inclusions
from the metal in the ladle and particularly in i-ts
ability to avoid saturation by the non-metallic inclusions
as the same are moved progressi~ely upward through the
expanded ladle covering compound on the surface o~ the
~7 molten me-tal.
from a molten metal bath with or wi-thout external or mechanical
agi-tation and has the unique ability of an immediate absorp-
tion capability with -the absorbed non-metallic inclusions
progressively moved in the covering compound so as to avoid
satura-tion o-f the same.
Description of the Pre~err~d Embodiment
The ladle covering compound in accordance with one
embodiment o-f the invention will upon being placed in a
cover,ing layer on the molten metal in a ladle without delay
immediately begin a controlled expansion substantially
increasing the thickness of the covering layer and provide
an insulating cover that will substantially maintain the
temperature of the metal for a desirable time. More
importantly, the expanding ladle covering compound provides
an immediate absorption abili-ty with respect to the non-
metallic inclusions in -the molten metal and its controlledl
continuing expansion in addition to increasing its insulating
factor retains its absorbing ability over a desired period
of t,ime su'bstantially greater than the prior art compounds
due to the ability of the ladle covering compound and
its controlled continuous expansion to absorb non~metallic
inclusions from the molten metal without becoming saturated
in the areas thereof in contac-t with the molten metal
and -those areas thereof immediately adjacent thereto.
The ladle co~ering compound continues to a~s~rb
non-metallic inclusions from the metal coming in contact
therewith and are retained in the compound for a sub~
28 stantially greater period of time than has heretofore
,
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believed possible, -thus insuring against non-metallic
reversion. A typical ladle covering compound ~ormed in
accordance with this invention wil-l have an expansion ratio
of from 15% 25% by volume. A typical example of the ladle
covering compound may comprise burnt lime 58% by weight,
aluminum dross 30% by weight, fluorspar 8% by weight and
acid treated graphi-te 4% by weight.
The ladle covering compound o~ the foregoing example
may be advantageously modified by varying the amounts
of the materials comprising the composition. For example,
the burnt lime may be present in amounts between 56% by
weight and 60% by weight, the aluminum dross in amoun-ts
between 22% by welght and 30% by weight, the fluorspar
in amounts between 7% by weight and 9% by weight and the
acid treated graphi-te i~ amounts between 1% and 4% by weight.
A typical batch formed in accordance with a preferred
example of the invention and totaling 3,000 lbs. would
therefore incorporate 1,830 lbs. of burnt lime, 930 lbs.
of alumlnum dross, 230 lbs. of fluorspar and 10 lbs. of
acid treated graphite flakes, These materials are thoroughly
mixed and may be used as mixed in their granular or powder
form for direct application to the hot metal in a ladle.
It will occur to those skilled in the art that the amount
of the ladle covering material placed on the molten metal
also affects the insulation factor and the time factor of
the continuously expanding action of the compound and its
continuing ability to absorb non-metallic inclusions from
28 the metal.
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Alternately, the above-described compound may be formed
in board form by the addition of a suitable bonding material
which may comprise re~in urea ~orm~ldehyde or sodium silicate
or phenolic resins or other glue-like binders as known in
the art.* Appropriately formed boards may be of varying
thicknesses and desirable overall perimeter sizes to
facilita-te handling of the same in placing them on the
molten metal in the ladle. In use such boards rapidly
disintegrate and form the covering layer, which is
immediately capable of absorbing non-metallic inclusions
from the molten metal.
Those skilled in the art will observe that the material
of the ladle covering compound may be varied and one such
variation advantageously improving the expansion time and
volume may comprise burnt lime 58% by weight, magnesium
oxide 1% by weigh-t, silica oxide 3% by weight, fluorspar
7% by weight, iron oxide 1% by weight, aluminum dross 18~o
by weight and aluminum 12,~ by weight.
The modified compound may be altered as to the amounts
2a o~ the several materials o~ the composition to alter the
rate a~d volume oi the expansion resulting within the
~ollowing ranges: burnt lime between about 56% and 60%
by weight, magnesium oxide between about 1% and 2% by weight,
silica oxide between about 3% and 5% by weight, ~luorspar
between about 7~0 and 9% by weight, iron oxide between
about one-hal~ o~ one percen-t and 1,o by weight, aluminum
27 dross between about 14% and 18% by weight, and aluminum
.
* For example 30% by weight.
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such as perlite, acid treated graphite, vermicnlite, kalin
clays and other products that expand under heat, such as
baking soda, crystal ammonia and the like~ The melting
points and the expansion characteristics of each of these
materials is usedin selec-ting the variance in the basic
composition so that the thickness o~ the covering compound,
the length of the continuing expansi.on, and the continuing
ability of the compound to absorb non-metallic inclusions
from the metal may be controlled.
It will occur to those skilled in the art that the
ladle covering compound disclosed herein may be used in
any melting iurnace as an instant artificial slag acting
as a metal refining agent.
It will thus be seen that the ladle covering compound
disclosed herein when positioned on molten metal in a ladle
forms a virgin, instant slag with precalculated absorption
abilities capable of retaining non-metallic elements directed
thereagainst by -the supporting molten metal with or without
external or internal agitation.
~l~hough but two embodiments of -the present invention
have been described in the foregoing specification, it will
be apparen-t to those skilled ;in the art that various
modifications may be made therein without departing from
the spirit of the invention.
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