PROCEDE POUR DIMINUER LA TENEUR EN SOUFRE DE PRODUITS AU VANADIUM-CARBONE AJOUTES AUX ACIERS

PROCESS FOR LOWERING THE SULFUR CONTENT OF VANADIUM- CARBON MATERIALS USED AS ADDITIONS TO STEEL

Abrégé anglais

9509
PROCESS FOR LOWERING THE SULFUR
CONTENT OF VANADIUM-CARBON
MATERIALS USED AS ADDITIONS TO STEEL
Abstract of the Disclosure
Vanadium-carbon materials for use as additions
to steel have been produced by the vacuum furnacing of a
mixture of vanadium oxide and carbon. To lower the
sulfur content of such material, which derives essentially
from the sulfur content of the carbon in the mixture, a
relatively small quantity of silicon, silica or tin is
included in the mixture prior to vacuum furnacing.
S P E C I F I C A T I O N
1.

Revendications

9509
WHAT IS CLAIMED IS:
1. In the manufacture of a vanadium and
carbon containing material at least about 80% by
weight being in the form of combined vanadium and
carbon with the predominant proportion of combined
vanadium being in the form of V2C and the atomic
ratio of vanadium to carbon being in the range of
1.49 to 2.42, by vacuum furnacing of a mixture of
vanadium oxide and a carbon source material contain-
ing sulfur, the improvement for lowering the sulfur
content of said material which comprises adding to
said mixture prior to furnacing thereof at least one
material selected from the group consisting of silicon,
silica and tin wherein the aggregate amount of silicon
and tin is from about 1 to 9 times by weight the
amount of sulfur in the carbon constituent in the mix-
ture of vanadium oxide and carbon.
2. A method in accordance with claim 1
wherein said selected material is silicon wherein the
amount of said silicon is from about 1 to 9 times by
weight the amount of sulfur in the carbon constituent
in the mixture of vanadium oxide and carbon.
3. A method in accordance with claim 1
wherein said selected material is silica wherein the
amount of silicon present in said silica is from about
1 to 9 times by weight the amount of sulfur in the
carbon constituent in the mixture of vanadium oxide
and carbon.
4. A method in accordance with claim 1
wherein said selected material is tin wherein the amount
of said tin is from about 1 to 5 times by weight the
amount of sulfur in the carbon constituent in the mix-
ture of vanadium oxide and carbon.
7.

Description

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The present invention is directed to a
method for lowering the sulfur content in materials
containing vanadium and carbon which are produced
by the vacuum furnacing of a mixture of vanadium
oxide and carbon.
Vanadium-carbon materials of the type noted
above are produced by the high temperature vacuum
furnacing of vanadium oxide and carbon as described
for example in U.S. Patent 3,334,992 - J. H. Downing
and R. F, Merkert,
The vanadium-carbon materials disclosed
in the above-noted patent are produced by a method
which includes the steps of mixing of V203 and carbon,
compacting the mixture into briquets and vacuum fur-
nacing the mixture at elevated temperatures, e.g.
1200C to 1400C at a pressure of less than about
300 microns, to produce a product in which is sub-
stantially all in th~ form of combined vanadium and
carbon. This material is widely used as a vanadium
source addition to molten steel. It has been found
that the sulfur content of such vanadium-carbon product
is on the order of about 1/3 sulfur content of the
starting mixture of V203 and carbon, the sulfur content
of the starting mixture being essentially due to the
sulfur content of the carbon source, e.g. coal, carbon
black and the like.
2.
q~

9~09
1~9~13S
Since it is undesirable to add sulfur im-
purities to steel, it is important to lower the
sulfur content of vanadium-carbon materials as des-
cribed above, particularly when low sulfur carbon
materials are not readily available.
It is therefore an object of the present
invention to provide a method for lowering the sulfur
content of vanadium-carbon materials produced by the
vacuum furnacing of a mixture of a vanadium oxide and
carbon.
Other objects will be apparent from the
following description and claims.
A method in accordance with the present in-
vention comprises including in a mixture of vanadium
oxide and carbon which contains sulfur as an impurity,
a minor proportion of at least one material selected
from the group consisting of silicon, silica and tin,
and vacuum furnacing said mixture to provide a material
which is substantially all in the form of combined
vanadium and carbon, i,e. at least about 80% by weight,
and which has a sulfur content substantially lower than
that of the starting mixture.
In the practice of a particular embodiment
of the present invention, a mixture of finely divided
V203 and carbon is prepared and at least one of a
finely divided material selected from the group of
silicon, silica and tin is included in the mixture.
The aggregate amount selected material, when the selected
material is tin, is from about 1 to 5 times the weight of
sulfur in the carbon constituent of mixture. When the
selected material is silicon or silica, the aggregate
amount of the silicon present is about 1 to 9 times the
weight of sulfur in the carbon constituent of the mixture.
The mixture
3.

1~9~35 9509
is thereafter briquetted and subjected to a temperature
in the range of about 1200C to 1400C in a vacuum
furnace wherein the mixture constituents are reacted,
the reaction being completed at a pressure of less than
about 300 microns; the reaction time being sufficient to
cause the carbon and V203 to combine and form a product
~` which is at least 80% by weight in the form of combined
vanadium and carbon. The sulfur content of thus produced
material will be less than about 0.05V/o by weight.
10The following example will further illustrate
the present invention. The mesh sizes in the examples
are U.S. Screen Series.

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EXAMPLE I (895)
A mix was prepared containing 1000 lbs. of
V203 sized _2~, 335 lbs. of petroleum coke containing
0.65% sulfur sized -2~,20 lbs. of Mogul* binder (a
cereal binder comprising gelatinized corn starch) and
23% water based on dry weight. Briquets sized 1-3/4" x 1-1/4
x 1" were prepared from the mix by pressing in a K-G
roll briquet press and drying at 225Fo The resulting
briquets, in the amount of 3 lbs., were charged to a
vacuum furnace having interior working dimensions of
711 x 12" x 40". The pressure in the furnace was re-
duced to 175 microns and the furnace was heated to
1400C. Due to evolution of C0 the pressure rose to
about 1600 microns. After about 8 hours at 1400C.
The pressure dropped to 100 microns and the furnace
contents were then cooled to room temperature under a
positive pressure of argon. The product briquets
analyzed 8.49% combined carbon and 0.18% sulfur.
EXAMPLE II (902)
Essentially the same procedure as in Example
I was followed, except that the mix contained 1.7%
silicon based on the weight of V203 sized 200 M x D.
The resulting briquets contained 7~ 94% combined carbon
and 0.013% sulfur.
EXAMPLE III (903)
Essentially the same procedure as in Example
I was followed, except that the mix contained 0.5% tin
based on the weight of V203 sized 100 M x D. The re-
sulting briquets contained 7.44% combined carbon and
0.042% sulfur.
*Trademark of Corn Products Company

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EXAMPLE IV (905)
: Essentially the same procedure as in
Example I was followed, except that the mix contained
3.6% SiO2 based on the weight of V203 sized 200 M x D.
The resulting briquets contained 9.34% combined carbon
and 0.012% sulfur.