Improvements in or relating to Electric Furnaces.
Year: 1897

page_text: Date of Application in the United Kingdom, 27th July, 1897
Complete Left, 27th July, 1897-Accepted, 5th Mar., 1898
Improvements in or relating to Electric Furnaces.
I, ISAIAH LEWIS ROBERTS, of Niagara Falls, in the County of Niagara, State
of New York, United States of America, Engineer, do hereby declare the nature
of this invention, and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement:-
Metallic carbides have heretofore been produced by the electric arc in a mass
of carbon and oxide by elevating or drawing away one electrode from the other,
and after some carbide has been thus produced on or in one electrode, as in a pot
or crucible, the said carbide comes to be a part of said crucible or electrode, being
electrically connected thereto. Carbides have also been attempted to be made by
bringing the said mixture into contact with highly heated conducting carbon rods
or bars, and also by arranging a number of pieces of conducting carbon end to
end through a mass of carbon and oxide particles forming a continuous conductor,
and by other methods; but my invention relates. to mechanically moving a mass
of oxide and carbon particles between two electrodes and establishing a body of
carbide between them, and moving the latter away from both electrodes con-
tinuously or at such intervals or rate. that the current of electricity is not broken.
This method of producing carbides has several advantages over those mentioned
above, such as saving of electrodes which, in most of the methods, are rapidly
destroyed, and also in that it is continuous and therefore avoids the necessity of
idle furnaces in an intermittent process.
Inasmuch as my process is one in which the carbides are made within the
mixed mass and removed as formed, there is less volatilization of the carbide after
formation than is the case with the stationary are method. In my process the
formation of the carbide takes place in the mass of a non-conducting material, and
therefore little or no heat is lost by radiation.
In order to carry out the above-described process, I make use of the apparatus
shown in the accompanying drawings, in which like letters refer to like parts in
all of them, and in which
Figure 1 is a vertical cross section of my apparatus ;
Figure 2 is a longitudinal cross section;
Figure 3 is a plan cross section ;
Figure 4 shows the position of the electrodes on starting;
Figure 5 is a longitudinal cross section of a modified form of apparatus ;
anoce contion thereof and

page_text: Figure 7 is a vertical cross section along line 7-7 of Figure 5.
To construct the apparatus and practice the process, I proceed as follows:
I construct a sheet iron container, which may be open at one end and closed at
the other, except for the hopper or chute B, Figure 2. Beneath the chute the
endless belt C, Figs. 1 and 2, is arranged, which is held up by the rollers c, c, c, c,
and driven in the direction of the arrows by the driving roller D. The edges of
the belt run beneath the turned under strips of sheet metal d, d, Figure 1, which
prevents leakage of the material. I prefer to make this belt of wire cloth, each
wire previous to being woven being covered with asbestos thread, thus making said
belt impervious to the pulverized carbon and oxide it must carry, and also strong
and capable of withstanding considerable heat. I prefer to make the frame E
and rollers c, c, c, c, of iron.
To operate this apparatus and make carbide I first place two carbon elec-
trodes F, F, in the position shown in Fig. 4. These are pushed through adjustable
stuffing-boxes, H, H, having asbestos packing, which insulates the said electrodes
from the iron casing A. The packing is contained in an adjustable support, as
for instance, a ball and socket joint R, allowing the electrodes to swing inwards
and together, as shown in Figure 4. These electrodes are held by metal holders, I, I,
which are attached to or are made integral with screw spindles J, J, and have
insulated hand-wheels j,j, attached thereto. The said screw spindle passes
through a screw block K, which has an attachment for an electrical conductor.
In order that the electrodes may travel in the same plane when adjusted, their
lower ends are supported upon fixed plates P, having slots r, serving as tracks for
the lower ends of the blocks K. They can be guided upon the plates P by pins S,
moving in the radial slots r. Having inserted the electrodes, I bring the ends
together, as shown in Fig. 4, and fill the container or casing A, with the above
described mixture L, through the hopper or chute B. I then start a small current
at first through the circuit made by the contact of the two electrodes and then
slightly separate them by drawing the hand wheels and supports K, K, toward
each other. This increases the resistance by making an arc, which at once begins
to produce carbide. I then increase the current and continue to separate the
electrodes by manipulating them at the stuffing boxes H, H, and at the same time
increasing the current as fast as the carbide is made in quantity sufficient to
maintain the circuit. When the said electrodes have been forced apart as far as
the mass about them will permit, then the worm screw pulley D, is moved so as
to cause the belt C to move in the direction of the arrows, and this will draw the
mass of molten carbide between the electrodes slightly outward and tend to bring
the electrodes further apart until parallel. The current should then be further
increased and the belt slowly moved until the electrodes are parallel, when the
current should be increased to that quantity suitable to the capacity of the elec-
trodes to carry it without undue heat. If more convenient, the current may be
started between parallel electrodes by placing some pieces of broken carbon between
the ends of them, which will be a temporary conductor until a bridge of carbide
is formed. When this is done, a continuous slab of carbide will be formed, as
shown at M, Figs. 2 and 3. It may have an arched shape, if the belt is properly
speeded, as shown in Fig. 3. The speed of the belt must not be so great as to
break the current. The quantity of the current diminishes as the speed of the
belt increases, because the slab of conductive carbide becomes thinner and the arch
or crescent longer and consequently of higher resistance; and the current
increases as the speed is diminished, because the said slab becomes thicker and
the arch shorter.
The slab M, of carbide may thus be made of any desired thickness or any width
that may be desired or permissible in the apparatus. As the slab M, is drawn
toward the outlet the unconverted mixture under it falls over the driving roller D,
into any receptacle, and may be returned to the chute B, to again go through the
apparatus, while the piece of protruding carbide may be broken off in pieces by

page_text: striking it, and transferred by tongs or other means, while any unreduced
materials adhering thereto may also be removed and returned to the chute B.
The material in the said chute takes the course of the arrows, and being mostly
a cool or fresh mixture, it does not heat the electrodes, but tends to keep them cool
and protects them from the air, and therefore preserves them.
The said slab of carbide extends from one electrode to the other, and is thus
maintained and builded up by the heat of the current which passes on the route
of the least resistance between them. The heat thus added by the resistance to its
passage by the mass of carbide, is preserved and kept insulated by the non-con-
ducting mass above and below it, thus causing the energy of the current to
perform its utmost work. The gases generated by the decomposition of the oxides
escape along the top of the casing and up the flue or stack N.
In the modification shown in Figs. 5, 6, and 7 the electrodes are placed on the
top of the casing in front of the hopper, and project obliquely downward, one of
said electrodes being in advance of the other, and each being provided with a
cap i, to which is attached the circuit wire, and a set screw Q being provided for
securing the electrodes in any desired position.
It is plain that my invention, though specially applicable to the making of
metallic carbides, is not limited in its broader aspects to such production, but may
be used for other, metallurgical operations, as, for instance, for making car-
borundum from silicon oxide and carbon, or the reduction of metallic oxides which
are themselves practically non-conductors but become sufficiently conducting when
reduced.
"6
When in this specification and its claims I use the word ore" I mean to be
understood thereby as meaning not only the bodies technically called ores, but such
bodies as calcium oxide and other oxides.
Though I have shown the belt as suitably extended for the purpose of cooling
the slab before it is removed, yet, in some cases, the belt need only be extended
far enough to form the material which, then in a molten condition, can be
separated and allowed to flow over the returning end of the belt.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. As an improvement in the art of metallurgy, the process of converting or
changing an ore, substantially an insulator of electricity, which consists in estab-
lishing between electrodes within a non-conducting mixture of pulverized or
granulated ore or oxide and a reducing agent, a conducting path of material which
will be heated to incandescence by the passage of a current, passing electricity
through said path and by the heat therefrom converting the adjacent portions of
the mixture into a conductive body, and gradually drawing the mixture between
the electrodes in a direction transverse to the direction of flow of the current
through said path, whereby successive portions of the mixture are successively
brought into the heating field and thereby converted into a conducting body and
caused to act as an incandescent conductor to reduce the adjacent portions of the
mixture, substantially as described.
2. As an improvement in the art of metallurgy, the process of converting or
changing an ore, substantially an insulator of electricity, which consists in estab-
lishing between electrodes within a non-conducting mixture of pulverized ore or
oxide and carbon, a conducting path of material which will be heated to incan-
descence by the passage of a current, passing electricity through said path and by
the heat therefrom converting the adjacent portions of the mixture into a con-
ductive body, and gradually drawing the mixture between the electrodes in a
direction transverse to the direction of flow of the current through said path,
whereby successive portions of the mixture are successively brought into the
heating field and thereby converted into a conductive body and caused to act as

page_text: an incandescent conductor to reduce the adjacent portions of the mixture, sub-
stantially as described.
3. As an improvement in the art of metallurgy, the process of converting or
changing an ore of calcium commingled with carbon, substantially an insulator
of electricity, which consists in establishing between electrodes within a non-
conducting mixture of pulverized or granulated calcium oxide and carbon, a
conducting path of material which will be heated to incandescence by the passage
of a current, passing electricity through said path and by the heat therefrom
converting the adjacent portions of the mixture into a calcium carbide, and
gradually drawing the mixture between the electrodes in a direction transverse
to the direction of flow of the current through said path, whereby successive
portions of the mixture are successively brought into the heating field and thereby
converted into a conducting body and caused to act as an incandescent conductor
to reduce the adjacent portions of the mixture, substantially as described.
4. As an improvement in the art of metallurgy, the process of converting or
changing an ore of calcium commingled with carbon, substantially an insulator
of electricity, which consists in establishing between electrodes within a non-
conducting mixture of pulverized or granulated calcium oxide and carbon, a
conducting path of material which will be heated to incandescence by the passage
of a current, passing electricity through said path and by the heat therefrom
converting the adjacent portions of the mixture into calcium carbide, and grad-
ually passing the mixture between the electrodes in a direction transverse to the
direction of How of the current through said path, whereby successive portions of
the mixture are successively brought into the heating field and thereby converted
into a conducting body and caused to act as an incandescent conductor to reduce
the adjacent portions of the mixture, and maintaining the resulting slab of carbide
within a surrounding cover of unconverted material, substantially as described.
5. The process of producing metallic carbides, which consists in surrounding
horizontal electrodes with a mass of pulverized oxide and carbon, in establishing
a temporary conducting path between said electrodes, in passing the pulverized
mass of oxide and carbon horizontally between the electrodes without breaking
contact with the produced carbide, in gradually widening the said slab of produced
carbide by the gradual withdrawal of the electrodes, and in finally forming carbide
by moving the mixed mass between parallel electrodes extending in the direction
of travel of the mass, thereby forming such slab of carbide of the full width of the
distance between the electrodes, and in supplying sufficient unconverted material
to surround the electrodes and the slab so formed, and in simultaneously moving
said unconverted material onward again with the so formed carbide, substantially
as described.
6. In an apparatus for effecting metallurgical operations, the combination of a
continuous horizontal mechanical conveyor, two electrodes located in proximity
thereto, and means for feeding a mass of material to be treated onto said conveyor
above and below said electrodes, thereby enclosing them in a mass of the material
to be treated in their operation, substantially as described.
7. The combination in an apparatus for effecting metallurgical operations of
an endless, continuous, horizontal, mechanical conveyor, and two horizontally
adjustable electrodes placed in proximity thereto, capable of taking a parallel
position, thereby affecting material moved by said conveyor, substantially as
described.
8. In an apparatus for the treatment of substances by electrical heat, the com-
bination of a conveyor made of wire cloth, the wires of which are severally covered
with asbestos, and two electrodes located in proximity to said conveyor, sub-
stantially as described.
9. The combination in an apparatus for effecting electrical conversion, of a
continuous horizontal, mechanical conveyor, and two horizontal electrodes arranged
in proximity to its upper surface, substantially as and for the purposes described.
10. The combination in an apparatus for affecting electrical conversion, of a

page_text: continuous, horizontal, mechanical conveyor, two horizontal electrodes arranged
in proximity to its upper surface, and means for causing the said electrodes to
travel above said conveyor and in the same horizontal plane, substantially as
described.
11. The combination in an apparatus for effecting electrical conversion, of the
belt C, horizontally adjustable electrodes in proximity thereto, the adjustable
supports R located above the belt and aiding in supporting the electrodes, and the
plates P, located outside of the casing of the apparatus and carrying the moving
holders of the electrodes, substantially as described.
ISAIAH LEWIS ROBERTS.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.