Note: Descriptions are shown in the official language in which they were submitted.
~5~5~6
This invention relates to a particulate slagging
composition useful for the continuous casting of steels and to
a process for using said particulate slagging composition.
A variety of particulate slagging compositions, also
referred to as "mold powders", "slags", or "fluxes", have been
proposed for the continuous casting of steel, a fairly recent
development in steel mill prac~ice. Such materials protect
the molten metal from air oxidation while usually fluxing or
solubili~ing and thereby removing some oxide impurities present
in the steel melt. Additionally, lubrication of the mold often
can be enhanced by the use of such materials. Typically, the
"~ material is fed or poured on the top surface of the molten metal.
Occasionally this top is referred to as the meniscus.
In the art, the terms "flux", "slag", or "mold powders"
often have been used interchangeably for fritted or preponder-
antly fritted material to be used in continuous castlng service.
For convenience, a particulate slagging composition will be
defined as encompassing all types of materials used to pro~ect
and lubricate the steel during continuous casting. A "vitrifac-
~a tion" will be defined as a totally vitrified ~r~t~ed~material
or mixture of fritted material for the instant purpose. A "flux"
-1- ~
will be a vitrifaction to which there is added non-vitrified
material in small proportion, that is, less than about 30% of the
total flux. Separate from both flux and vitrifaction, are "mold
powders" which shall be defined as essentially raw materials which
have not been vitrified to any appreciable extent. Typically, the
instant particulate slagging compositions without carbon are made
by comminuting the components and/or vitrified components, then
blending if necessary. The exemplified vitreous fluxes shown in
U.S. Patent 3,926,246 and U.S. Patent 4,092,159 feature a portion
~ ~f the fluorine-providing material mixed unfritted with the bal-
ance of the glass formers which are fritted. This is done to
minimize smelter attack during making of the fritted portion of
the particulate slagging composition. ordinarily from 1-10% and
~"~
' preferably 1-5% by weight of powdered graphite is added to make
~ the final continuous casting particulate slagging composition.
Such graphite is for the purpose of minimizing heat loss from the
surface of the molten metal.
Steels now continuously cast in production operations
include various aluminum-killed steel, silicon-killed steel, and
austenitic stainless steel. The problems involved in formulating
a particulate slagging composition for use in continuous casting
' steel have been addressed in previous industry literature. Spe-
cifically, U.S. Patents 3,649,249, 3,704,744, and 3,899,324 show
some of the attempts by others to maximize the performance of the
particulate slagging compositions used.
Recognition has also been given in the industry litera-
ture to a problem concerning the absorption of alumina into the
melted slagging composition during continuous casting. The
alumina comes from the steel being cast. The problem is the most
severe when aluminum-killed steel is being cast. of course,
aluminum-killed steel is the predomlnant type of steel produced
by continuous casters. The absorption of alumina into the partic-
ulate slagging composition leads to an eventual deterioration in
performance characteristics. As the continuous casting run of
steel is extended in time, more and more alumina is absorbed into
the molten particulate slagging composition. After a certain
, 10 optimum casting run length, the molten particulate slagging com-
position's performance so deteriorates that the caster's steel
~ ~ output must be slowed down because the molten composition cannot
transfer heat away from the forming solid steel shell fast enough
to thicken the shell sufficiently. Also, the surface of the steel
1~ being cast shows more and more inclusions because the molten slag-
` ging composition cannot absorb impurities, primarily alumina, from
;the molten steel fast enough. The certain optimum casting run
, length differs for each ind~ividual caster and type of steel being
cast. The amount of protection the molten steel receives from
~0 ` the air while on its way to and in going through the caster influ-
ences the amount of alumina created and later evolved during cast-
` ing. In some casters the optimum casting run length can be as
short as 45 minutes. This length is even shorter than the time
required for a single heat of steel to be cast. In some casters,
with much better protection, the optimum casting run length can
be up to 8 or more hours, representing casting of several heats
; of steel without interruption.
-- 3 --
The performance characteristics of the molten partic-
ulate slagging composition can deteriorate to such an extent that
unacceptable surfaces on the steel being cast result. Also, with
the evolution of more and more alumina into the slag, the viscos-
ity of the molten composition can rise to such a high value that
necessary lubrication of the mold is no longer provided. The
rise in viscosity can hinder the liquid slagging composition's
movemen-t into the space between the mold wall and the forming
solid steel shell. When the gap is unlubricated due to the
absence of liquid slag, the steel shell can seize on the mold
wall and the resulting danger of a breakout becomes unacceptable.
Finally, the heat transfer value can lessen to such an extent
-that not a thick enough solid steel shell is created in the mold
and the chances for a breakout through a smaller hole also become
~ unacceptable. When any of these three things, or a combination
of things, happens the caster must either be shut down immedi-
ately or the casting run interrupted. These shutdowns or inter-
ruptions happen in spite of the fact that the molten pool of
particulate slagging composition covering the molten steel
receives continuous additions of the unmelted particulate slag-
ging composition. Thus, the problem of alumina absorption is
more than just the problem of adding more mold powder, which of
course is itself expensive. The alumina absorption problem, in
fact, leads to shorter, inefficient, costly casting runs on the
~5 , continuous caster.
Previous attempts to deal with this problem have
focused on the so-called "V" ratio. The "V" ratio is generally
- 4
~l5~
defined as the lime to silica ratio. Koenig and Hofmanner in
. United States Patent 3,788,840 require a lime-silica ratio in
the flux powder to be in the range of 0.7 - 1Ø This arrange-
ment is achieved by the addition of quartz powder. Koenig and
` Hofmanner in their '840 patent also require the aluminum oxide
content of the powder to be in the range of 2 - 12% by weight.
~hile helping to improve the performance characteristics of
their flux powder on a continuous casting run, the flux powder
cannot t~ithstand the addition of great amounts of alumina ex-
perienced in an extended run and allow optimum casting to
continue. An advantage of the instant particulate slagging
composition is the greater ability to absorb more alumina,
thus extending the length of the optimum continuous casting
run possible.
One aspect of this invention is a particulate slag-
ging composition for the continuous casting of steel, said
steel tending to evolve alumina into said composi~ion when
said composition is in molten condition during its use in the
continuous casting operation, said slagging composition being
characterized by flowidity of about 4 to 16 inches, fusion
range not substantially above 2300F., a Start-up ADK value
not exceeding 500 seconds, said composition further character-
ized b~ having the following theoretical net oxide anal~sis,
wherein the percentages are weight percentages and are selected
to total 100%:
~ 5
~ Sq~51
:'
Fluxing Ingredients Wt. %
CaO* O - 42
MgO* O - 20
BaO* O - 20
SrO* O - 20
; MnO* O - 20
FeO* O - 18
F* Celemental component of 4 - 16
the fluorine - providing
material~
B203* 0 - 15
Na20 1 - 25
K20 0 - 5
Li20 0 - 5
V25 0 - 1
NiO O - 2
CuO O - 2
ZnO O - 1
TiO2 0 - 5
; Zr2 0 - 3
~ CoO O - 2
Cr203 0 - 2
MoO3 0 - 1
Glass Network Formers
.
SiO2 20 ~ 40
A1203 0 - 12
205 o 10
` B203 included above;
.
516
the ratio of the sum of the theoretical net oxide analysis values
of the starred (*) fluxing ingredients to the theoretical net
oxide analysis value of SiO2 ~this ratio being termed the R' ratio)
being preselected between 1.5:1 and 3:1 for obtaining an Opera-
tional ADK value not substantially in excess of 750 seconds.
Another aspect of this invention is the improvement in
the process for the continuous casting of steel wherein a pool of
molten steel is maintained in the upper end of an open-ended con-
tinuous casting mold, the improvement which comprises establishing
and maintaining on the top of said pool a protective layer of the
particulate slagging composition hereinbefore defined.
Preferably 1 - 10% of finely divided carbon particles
is admixed with the composition.
The vitrifaction or vitrified fraction of the instant
flux is made conventionally in a smelter or the like. Molten
glass from the smelter conventionally is fritted by pouring a
stream of it into water or by fracturing it subse~uent to its
passage between chilled rolls. Often the resulting frit is
milled ~ground) to pass 150 mesh ~Tyler Standard) or finer for
use in continuous casting.
Such rit basically is made from glass network formers
and fluxing agents therefor. Glass network formers include
silica, boria, and alumina, with silica being the principal one.
Phosphorus pentoxide also is a useful glass network former, but
less desirable for steel fluxing, particularly with the particu-
late slagging compositions of this invention. Principal fluxing
5~~
-~ oxides are Group lA and 2A metal oxides, typically, potassium
oxide, sodium oxide, calcium oxide, magnesium oxide, strontlum
oxide, barium oxide, iron oxide (FeO), manganese oxide, and
lithium oxide. Copper oxide, nickel oxide, phosphorus pentoxide
and zinc oxide can also act as fluxing agents, but their use in
particulate slagging compositions is unusual because these four
oxides sometimes degrade the surface of the same types of metal
being cast. In the proportions that they can be used in the
present compositions, the other oxides of Period IV metals having
atomic number of 22-30, inclusive, the oxides of titania, cobalt,
manganese, chromium, vanadium as well as zirconium oxide and
molybdenum oxide act as fluxes. Some people prefer to consider
them as glass modifiers, particularly when they are used in a
greater proportion~ Vanadium, phosphorus and molybdenum oxides
1~ are not recommended for use since they may cause serious problems
with the water added to end the casting run. Fluorine also acts
to dissolve alumina and also to flux generally.
The vitrified part of the instant flux can be one or a
plurality of frits. In the latter case the frits can be agglomer~
"~ 0 ated,- such as by sintering. ~owever, mere mechanical mixing of
the frits is adequate and preferred. The raw glass batch for the
` vitrified portion of the flux, namely the vitrifaction, usually
is in the form of minerals and chemicals of purity satisfactory
for glass making; this is a prudent criterion. The fluorine-
providing material can be si~lple or complex fluoride salts,
typically fluorspar, cryolite, alkali and alkaline earth metal
fluorides, and alkali metal fluosilicates. For use with steel a
:
preferred and most practical fluorine-providing raw material is
fluorspar, either synthetic or na-tural.
An alternate method of practicing this invention is a
mold powder made by intimately mechanical blending of the partic-
ulate raw batch components set forth above as frit ingredients.
The particles of the components are not greater than about 100
mesh in size (Tyler Sieve Series). The blend may be heated to
some extent, but not to the extent that the components start to
fuse together and form a vitrifaction. However, when the mold
powder is placed on the molten pool of steel in the caster, the
mold powder should me]t without residue and thereby avoid the
presence of igneous byproducts which cause surface defects on the
steel cast. The big advantage of a mold powder over a vitrifac-
tion or flux is the lower cost due to the fact that smelting of
the raw batch components is no longer required before use in
casting.
Different properties of the instant particulate slagging
compositions were measured by specific tests. Smelting tempera-
tures were taken by means of an optical pyrometer. The smelting
2~ temperatures were taken at the end of 14 minutes. Flowidity was
` measured by the method set out in U.S. Patent 3,649,249. Alumina
dissolution kinetics (hereafter called ADK) and fusion ranges
were measured by special tests, the procedures for which are
I explained later.
Different types of steel to be cast with the instant
particulate slagging compositions worked better when the composi-
tions have certain measured properties. Fusion range temperatures,
g _
35~l6
:`
as long as the upper limits were below the lowest ~emperatures of
the steel to be cast with the particular compositions, did not
affect the process of casting. A margin of safety of at least a
couple of hundred degrees Fahrenheit is preferred. However, the
type of killed steel is important in selecting the composition
with the right values for alumina dissolution kinetics and flow-
idity. In the case of aluminum-killed steel the flowidity value
must be over 4, but not over 16O The alumina dissolution kinetics
(ADK) should initially be in the lower end of the values for the
~ particulate slagging composition. The initial ADK value shall
hereafter be referred to as Start-up ADK to represent the charac-
teristics of a molten slagging composition at the start of a
casting run, before any appreciable amount of alumina has evolved
into the protective layer of slag. For austenitic stainless
steels and silicon-killed steels, the flowidity values of the
composition can be lower than 3, and its Start-up ADK ordinarily
need not be as favorable; thus the value in seconds for its
"alumina dissolution kinetics" in such instance can be a higher
number, but not exceeding 500 seconds. After sufficient alumina
has been absorbed from the steel being cast to bring the evolved
alumina percentage to 10% of the molten composition, the ADK
value should not exceed 750 seconds. This second ADK value shall
! hereafter be referred to as Operational ADK. Operational ADK
value is defined to be that ADK value obtained, by -the ADK test
procedure later described, from a sample of 225 wt. parts of
completely molten and vitrified slagging composition (exclusive of
any carbon added) in which there has been dissolved 25 wt. parts
-- 10 -- .
.
- of extra alumina (A12O3). In the event that the slagging composi-
tion so tested emits volatile material such as carbon dioxide in
the process of melting same, said 225 wt. parts is the non-
volatile residue.
Accordingly, should some such volatile components be
expected for such testing, the initial weight of unmelted slag-
ging composition should be augmented to account for same. In
this test it is customary to blend the particulate slagging com-
position for test with pulverulent extra Al o prior to melting
same.
The special test procedure used to determine the fusion
ranges in the previous examples required weighing out 3.00 grams
of the sample particulate slagging compositions. A weighed-out
~ sample was put into a pellet mold that would produce a 1/2-inch
(1.27 cm.) diameter pellet in cylindrical form. The mold was then
li put into a hydraulic press and subjected to a pressure of 5,000
pounds per square inch (350 kg./cm ). The pellet formed from the
sample material was placed in the center of a stainless steel
plate, 1/2-inch (1.27 cm.) thick and 2 inches (5.08 cm.) by
~0 ~ 2 inches (5.08 cm.) square. The plate with the pellet on it was
then placed in a furnace capable of supporting the plate in a
precisely level position tto avoid the melted composition from
running off the plate). The furnace was also capable of maintain-
o o o
` ing preselected temperatures between 1500 F. (816 C.) and 2300 F.
`` 25 ' (1260 C.). The sample was left in the furnacé for exac-tly 3-1/2
minutes.
- ' .
-- 11 --
.
~s~
Upon removal, the pellet was examined for any evidence
of softening, primarily rounding of the edges. If there were such
signs, the furnace temperature was taken as the lower fusion range
temperature. If there were no such signs, the furnace temperature
S was increased by 50 F. (17.8 C.) and a new pellet was heated at
the new temperature for exactly 3-l/2 minutes. After the lower
fusion range temperature was determined, the furnace temperature
continued to be increased by 50 F. (17.8 C.) intervals until the
upper fusion range temperature was determined. The upper temper-
ature was evidenced by the sample flowing out into a thin melt,
i.e. a puddle that had lost all cylindrical form.
The special test procedure used to determine alumina
;dissolution kinetics required the preparation of a graphite cruc-
ible without any drain holes. The crucible was prepared by boring
lS a l-l/2-inch (3.76 cm.) diameter by 5 inches (12.70 cm.) deep hole
in a 3-inch (7.62 cm.) diameter by 6 inches (15.24 cm.) in length
pure graphite electrode. Alumina tubing having an outer diameter
of 3/32 inch (.25 cm.) and an inner diameter of l/32 inch (.092
cm.) was cut into a 3/4-inch (1.89 cm.) segment with an abrasive-
~0 coated cut-off wheel. To hold the alumina tubing segment, a
; ` 3/32-inch (.48 cm.) diameter horizontal hole was drilled 1/4 inch
(.64 cm.) from the bottom of a rod .31 inches (0.8 cm.) in diam-
eter and 8.07 inches (20.5 cm.) in length made from electrode
grade graphite.
, A sample of 250 grams of the particulate slagging
, composition was placed in the crucible. The crucible was heated
o o
to a temperature of 2600 F. (1427 C.) by a 7.5 KW Lepel induction
- 12 -
~3~
furnace. While the crucible was being heated, the graphite rod
containing the alumina sample was suspended over the crucible.
This ensured a proper warm-up period which reduced the possibility
of the alumina tube fracturing upon submersion into the composi-
tion. However, the alumina was sufficiently far enough above the
melting composition such that no premature alumina dissolution
occurred.
When the crucible had reached the 2600 F. (1427 C.)
temperature according to an optical pyrometer reading, the alumina
sample was submerged. Within 30 seconds or less, the graphite rod
was withdrawn to check if the alumina sample had fractured. Sharp
irregular breaks usually near the sample tip would have indicated
fracture and the necessity to start the procedure again from the
beginning. If no fracturing was evident, the sample was resub-
merged. At 15-second intervals, the rod was withdrawn to see if
~dissolution had occurred. Dissoluticn occurred when no alumina
! remained in the rod. The test was run three times for each sample
so that an average value could be calculated as the reported test
` result.
Of the two test procedures above, the most important
one for the purposes of the instant invention is the ADK test.
~" ` The present invention is addressed to the control of the alumina~absorption characteristics after the particulate slagging com-
position has been used in a continuous caster for an appreciable
period of time. Because the melted poo] of particulate slagglng
composition is constantly absorbing more and more alumina evolved
fro~ the steel being cast, the characteristics of conventional
` - 13 -
.
slagging compositions change. The most important change is prim-
arily noticed as a change in the Start-up ~DK value to the Opera-
tionai ADK value. This change is usually an increase meaning that
the used slag will no longer absorb as much alumina as fast as
when the casting run started. Industry practice held that when
the "V" ratio (CaO/SiO2~ of the particulate slagging composition
exceeded approximately 1.2, the dissolubility of A1203 in the
melted composition tended to decrease. However, we have found
that when the numerator of the "V" ratio is expanded to include
other divalent fluxing ions, an increase in this ratio correlates
to an increased ability of the slag to absorb alumina throughout
a long optimum continuous casting run. This new ratio with an
expanded numerator we shall call the "R" ratio. Specifically,
the numerator of our "R" ratio is the sum of the theoretical net
oxide values of cao, MgO, BaO, Sro, MnO, FeO. Other divalent
fluxing ions such as Ni, Cu, Zn are not included in our "R" ratio
'`because these divalent fluxing ions have deleterious effects on
the surface of the steel being cast as well as affecting the steel
alloy ratios if the ions are reduced to elemental metal. In
addition, Zn would fume off and present health problems to the
workers near the caster head. The sum of the numerator is by
addition of the percentages of theoretical net oxide analysis
values for the divalent ions in the particulate slagging composi-
~ tion. The denominator of the "R" ratio remains the theoretical
I net oxide analysis value of silica.
A more sophisticated ratio for predicting the effect of
changing net oxide analysis percentages is the R' ratio. The R'
- 14 -
.
ratio shall be defined as the numerator consisting of the sum of
` the theoretical net oxide analysis values of the following compo-
nents of the particulate slagging composition: CaO, MgO, BaO,
SrO, MnO, FeO, B2O3, F, The denominator of the R' ratio will
still remain the theoretical net oxide analysis value of silica.
Finally, the following formula has been empirically
determined to predict the effect on the Start-up alumina dissolu~
tion kinetics value of some of the components used in making up
the particulate slagging compositions. A negative coefficient
1~ alongside the value for the theoretical net oxide analysis value
of the component in the raw ingredients would correspond to a
lesser alumina dissolution ]cinetics value. This lesser value
would represent a shorter alumina dissolution kinetics time which
indicates a molten particulate slagging composition that could
, .
more readily absorb alumina from the steel being cast. The
formula is:
AD~ = 1.894 + (-76.16)(F) + (-15.58)( B203) + (-12.77) (CaO)
+ (12.34)(SiO2) + (-2.562)( 2 3 2
(2.3335)(B2O3) + (-6.033)(F)(X20) +
~0 ~ (4.073)(F)(B2O3) + (7.872)(F)
*X2O represents the sum of Na2O and K2O theoretical net oxide
analysis percentage when the K2O to Na2O ratio is held at
` 1:8.
S This formula should not be expected to give exact alumina dis-
solution kinetic values, but merely estimate the quantitative
' effect on alumina dissolution kinetics for a given quantitative
change in one of the constituents in the formula.
` - 15 -
,
. ~.~ . .
5~
The following examples show ways in which the invention
`~ has been practiced, which should not be construed as limitiny the
invention. In this application, unless otherwise expressly noted,
all parts are parts by weight, all percentages are weight percent-
ages, all temperatures are in degrees Fahrenheit, with Celsius
temperatures in parentheses, and all particle sizes are according
to the Tyler Standard Sieve Series.
Two series of tests were run in all of the examples.
The first series was performed on the vitrifactions or mold
1~ powders after formulation. The values obtained would represent
the properties of the molten particulate slagging compositions at
the Start-up of a continuous casting run of steel. The second
series of tests to determine an Operational ADK value for a
sample prepared by adding to the particulate slagging composition
extra alumina in the amount sufficient to make 10% of the increased
weight of the added-to composition in molten condition be due to
;the addition of extra alumina. Because the increased weight is
that of the added-to composition in molten condition, the tester
must compensate for any weight loss due to volatilization of any `
2~ particulate slagging composition components by using more of the
composition. For instance, in preparing a 250-gram increased
weight sample for the Operational ADK test, if 10% of the partic-
ulate slagging composition is lost due to volatilization upon
melting, the tester would use not 225 grams, but 250 grams. To
this 250-gram amount of particulate slagging composition would be
added 25 grams of alumina to produce the 250 grams final weight
~- of molten, added-to slag in the crucible. The alumina would have
- 16 -
5~6
to be added as a cool raw ingredient to cool vitrifaction or
powders, of course, in order to undergo the flowidity test. The
values obtained after the addition of alumina, termed the
Operational ADK values, would represent the properties of the
molten particulate slagging compositions after an extended optimum
continuous casting run of alumina-evolving steel.
EXAMPLES 1-5
This first group of 5 particulate slagging compositions
were all mold powders. These examples were prepared by intimately
mechanically blending of the particulate raw batch components, none
of which were greater than about 100 mesh in size (Tyler Sieve
Series). The blends were not heated. The mold powders had the
following raw batch composition ingredients (shown by weight
parts):
~ EXAMPLE 1 2 3 4 5
134 12 234 0 16
CaCO3 712 420 0 0 309
CaF2 215 482 399 200 666
` SiO2 263 0 255 0 0
~ ICaolin 229 0 o o o
` Dolomite O 0 0 0 493
, Spodumene 0 0 482 0 0
Nepheline
Syenite 6 563 0 0 779
, Fe34 0 60 91 188 83
4 243 0 0 0 0
:
~ - 17 -
~ . .
5~
E~IPLE 1 - 2 3 4 5
BaC03 0 100 0 0 0
MgO 0 58 -0 0 0
Dehydrated
Borax 0 111 100- 112 154
Li2Co3 o o 86 0 0
NaF 0 0 157 0 0
,` Wollastonite 0 0 0 1500 0
The mold powders had the -following theoretical net
oxide analysis (shown in percent by weight):
EX~lPLE 1 2 3 4 5
``Na2O 5.6 5.9 16.2 1.7 6.0
CaO 37.9 33.8 16.2 41.6 35.1
F 7.2 13.5 14.8 4.8 14.0
~SiO2 26.8 20.6 32.2 37.7 21.4
: A12O3 7.8 11.3 7.2 0 8.2
M~O 0 0 0 0 5.0
j K2O 1.6 0 0 1.6
FeO 0.9 3.8 5.5 9.9 3.8
~0 ~ MnO 13.1 0 0 0 0
' B2O3 4 5 3 9 3.8 4.7
~, BaO 0 4.7 0 0 0
Li2o 0 0 3.9 0 0
~,
'
~ ~ .
~ - 18 -
.. . .
The mold powders had the following R ratio:
E~MPLE 1 2 3 4 5
2.0 2.1 0.7 1.4 2.1
Fusion ranges for the mold powders in F~ with the Celsius value
o
( C.) in parentheses were:
2150- 1900-- 1700- 2100- 1825-
2250 F.2000 2000 2200 1900
(11770 (1038- ( 927- (1149- ( 996-
1232 C.)1093) 1093) 1204) 1038)
The Herty flowidity values in inches before addition of extra
alumina were:
.' 5.0 6.0 6.0 4.0 8.0
The Start-up alumina dissolution kinetics values in seconds before
the addition of alumina were:
' 205 200 310 390 195
, After the addition of extra alumina sufficient to make
,` I up 10% of the final weight, the Herty flowidity values in inches
were:
5.25 4.75 1.75 2.~5 5.25
and the Operational ADK values in~seconds after addition were:
`~ 195 335 2145 495 465
The differences before and after addition of alumina in the Herty
flowidity values in inches were:
~, .
, ~ +0.25 -1.25 -4.25 -1.75 -2.75
`~ ' and differences in ADK values in seconds were: -
' -10 +125 +1835 +105 -t270
` '
.
.~ .
~i.
5~
From these five examples it can be seen that a high R
ratio leads to small changes in the Herty flowidity and ADK times
even after the addition of extra alumina, while a low R ratio as
in Example 3 leads to large changes.
EXAMPLES 6-11
-- The following six particulate slagging compositions were
all mold powders prepared and tested the same way as in Examples
1-5. The raw batch compositions (by weight parts) were:
E~AMPLE 6 7 8 9 10 11 ' .
sio 455 194 194 194 19~ 194
Dehydrated
Borax 165 165 165 165 165 165
2 3 311 311 311 311 311 311
CaF2 142 142 142 142 142 142
: 15 I CaCo3 885 443 0 0 0 0
' K2CO3 43 43 43 43 43 43
'~ ' Wollastonite 0 514 514 514 514 514
, ~i F
3 4 o 241 0
"MnO 0 0 0 0 241 0
~0 I BaCO3 0 0 0 0 0 313
` ~`MgO 0 0 241 0 0 0
The examples had the following theoretical net oxlde
~" analysis (shown in percent by weight):
.,; ,' ',.
~ , ,
, - 20 -
,
~5f~5~6
EXA~LE 6 7 8 9 lO 11
Na2O 15.4 15.4 15.4 15.4 15.4 15.4
CaO 28.8 38.8 22.8 22.8 22.8 22.8
B2O3 7.6 7.6 7.6 7.6 7.6 7.6
SiO2 30.8 30.8 30.8 30.8 30.8 30.8
K2O 1.9 1.9 1.9 1.9 1.9 1.9
F 4.6 4.6 4.6 4.6 4.6 4.6
FeO 0 0 0 16.0 0 0
~InO 0 0 0 0 16.0 0
BaO 16.0
~g 0 0 16.0 0 0 0
The mold powders all had the R ratios of 1.25.
Fusion ranges for the mold powders in F. ~C.~ were:
1875- 1875- 1700- 1650- 1700- 1700-
2000F. 2000 1850 1750 1800 1800
1024- (1024- ~ 927- ~ 899- ~ 927- ~ 927-
1093C.) 1093) 1010) 954) 982) 982)
The Herty flowidity value in inches before addition of extra alumina were:
7.0 7.25 7.75 5.25* 6.75 7.5
The Start-up alumina dissolution kinetics values in seconds before the addi-
tion of extra alumina were:
192 305 405 240* 250 390
*Composition so reactive in carbon crucible that
temperature of test was 2400F. ~1316C.) since
2600F. ~1427C.) could not be attained.
After the addition of extra alumina sufficient to make up 10% of
the final weight, the herty flowidity values in inches were:
.
s~
EX~MPLE 6 7 8 9 10 11
4.0 4.75 4.50 ~.0 3.75 3.75
` and the O erational ADK values in seconds after addition were:
255 425 593 345 330 540
The difference before and after addition of the Herty flowidity
values in inches were:
3.0 2.50 3.25 2.25 3.00 3.75
and differences in ADK values in seconds were:
+63 -55 +188 -15 +50 -15
.
These six examples all show mold powders that would be
satisfactory for use in an extended optimum continuous casting run
of steel.
` EXAMPLES 12-16
. .
` j The following five examples were all vitrifactions that
were formulated to yield the same theoretical net oxide analysis
, as the preceding examples,-except for Example 7. Correspond`ing to
the order of presentation, Example 12 has the same analysis as
., ,~; . .
`does Example 6 and so on, (i.e. 13 corresponds to 8, 14 to 9,
,15 to 10, and 16 to 11). The vitrifactions were prepared by
~ conventionally dry-mixing, fusing, and water quenching of the
` following raw batch ingredients listed by weight parts:
.~ I EX~MPLE 12 13 14 15 16
` ~SiO2 796 870 870 870 836
'. ~
~ - 22 -
. EXP~lPLE 12 13 14 15 16
,
Dehydrated
Borax 289 323 323 323 310
~a CO 544 608 608 608 585
2 3
CaF 248 278 278 278 267
CaCO3 1548 866 866 866 833
2 3 72 84 84 89 81
Fe34 0 0 471 0 0
. MnO 0 0 0 471 0
BaCO3 0 0 0 588
MgO 0 471 0 0 0
. The fluorine actually remaining in the frit was 3.4% by
;weight percent The R ratios for all the examples will correspond
~` to the previous examples the same way as do the theoretical net
`~ 15 oxide analysis values.
.~` !
"~ Fusion ranges for the vitrifactions in F., with the Celsius value .
( C.) in parentheses, were:
~- 1925-o 1725- 1675- 1725- 1700-
. 2050 F. 1950 1800 1800 1875
,
(1052-o ( 941- ( 912- ( 941- ( 927-
1121 C.) 1066) 982) 982) 1024)
.," : .
The Herty flowidity values in inches before addition of extra
alumina were:
6.75 5.5 2.25* 5.75 5.50
, The Start-up alumina dissolution kinetics value in seconds before
the addition of alumina were:
, 450 570 * 303 307
; - 23 -
.
5~
After the addition of extra alumina sufficient to make
up 10% of the final weight, the Herty flowidity values in inches
were: -
3.125 3.75 2.75* 3.50 3.25
and the Operational ADK values in seconds after addition were:
540 670 * 435 390
The differences before and after addition of Herty flowidity were:
-3.625 -1.75 +.50 -2.25 -2.25
and differences in ADK values were:
+90 +100 * ~132 ~83
' ,`
; *Composition so reactive in carbon crucible thattemperature of testO if any, was 2400 F. (1316 C.)
since 2600 F. (1427 C.) could not be attained.
.
~" From these five examples, it can be seen that a high R
'~ 15 ratio leads to small changes in the Herty flowidity and ADK times
~` , even after the addition of 10% alumina.
~ . .
'
.. ;~ ',
~`
.
~ - 24 -
,
.
5~6
!
Fluxinq Ingredients, Continued t ' .
Li2o 0-5
I V25 O- 1.
Nio 0-2
CuO 0-2
ZnO -
2 0-5
Zr2 0-3
CoO 0-2
23 0-2
MoO3 0-1
Glass Network Formers
. sio2 20-40
; A123 0 12
P205 o- 10
¦~ ~23 included above~
the ratio of the sum of the theoretical net oxide analysis
values of the starred (*) fluxing ingxedi.ents to th~ theoretical
~ net oxide analysis value oE sio2 (this ratio being termed the R'
: ratio) being preselected between 1.5:1 and 3:1 for obta.ining an
Operational ADK value not substantially in excess of 750 seconds.
.
` .
