Improvements in or relating to Electric Furnaces Applicable for Making Aluminium and for other Purposes.
Year: 1887

page_text: Date of Application, 29th Mar., 1887.
Specification Accepted, 29th Apr., 1887.
[Communicated from abroad by EUGENE HUTCHINSON COWLES and ALFRED.
HUTCHINSON COWLES, both of Cleveland, County of Cuyhoga, State of Ohio,
United States of America, Inventors.]
Improvements in or relating to Electric Furnaces Applicable for
Making Aluminium and for other Purposes.
I, WILLIAM PHILLIPS THOMPSON F.C.S. of the Agency for Foreign Patent
Solicitors 6, Lord Street Liverpool in the County of Lancaster, and 323 High
Holborn in the County of Middlesex Civil Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
-
This invention relates to furnaces in which the reduction of ores and chemical
compounds, the production of alloys, the refining of metals, and like metallurgical
operations are carried on by means of electricity.
This invention consists in the means by which the varying electrical resistance of
the charge in the furnace is made the primary agency in actuating and controlling the
feeding of the material to be smelted or reduced.
This invention also consists in the means of automatically regulating and controlling
the charging, feeding, and discharging of a furnace of the type hereinafter described
through the agency of the electrical resistance of the charge in the said furnace.
This invention further consists in the construction of the furnace, and in the
combination therewith of the feeding, discharging and resistance regulating apparatus
as hereinafter fully described and claimed; whereby the varying electrical resistance
of the charge in the furnace is made the primary agency in actuating and controlling
the feeding of the material to be smelted, and discharging the products.
Figure 1 in the drawing shows a furnace embodying this invention in vertical
section through the centre, with the automatic feed regulating apparatus attached
thereto.
Figure 2 is a modification of the mechanism for regulating the downward feed of
the charge.
Figure 3 is a side view of the automatic feed mechanism.
By means of this invention a desirable regularity and uniformity of feeding
or charging the furnace is effectually accomplished; and this important for many
reasons, prominent among which may be mentioned the fluctuations of the current
are governed and controlled within definite. limits; the draft upon the motive power

page_text: is made more constant and uniform ;-and the dynamo is relieved from the risks
attendant upon sudden or undue variations in the resistance of the external or
working circuit.
In order to more particularly describe the invention, reference is made to the
accompanying drawings, in which similar letters of reference indicate corresponding
parts in all the figures.
A, is the positive electrode, preferably made of electric light carbon in the form of
a pipe or hollow cylinder. B is the feed hopper, preferably made conical in form,
and having its lower end attached to the top of the positive electrode ( is the
negative electrode, also made of electric light carbon, in the form of a hollow cylinder,
and fastened to the plate D, which is built into the lower portion of the furnace, and
to which plate the negative wire of the circuit is connected, E are the furnace walls,
formed of fire-brick, silica, lime, or other refractory material.
F is a lining or filling of fine charcoal, pulverized lime and carbon, or other suitable
material; this lining surrounds the negative electrode Cand insulates it, and being a
bad conductor of heat as well as of electricity, it prevents the destruction of the lower
part of the walls and the bottom of the furnace, when the furnace is in operation.
G is also a lining of charcoal, lime, and carbon, or other suitable inaterial; this
lining surrounds the zone of fusion between the positive and negative electrodes, and
extends upwards around the said positive electrodes this lining G is similar in
function and character to the lining F, but is made of coarser material to provide for
the escape of the gases given off from the charge at the zone of fusion when heated by
the current, and is in contact, with the terminals of the electric circuit.
T is an escape pipe through which the aforesaid fumes and gases pass from the
upper part of the furnace into the condenser t.
His a plate covering the top of the furnace and having a hole in the top of it
through which the positive electrode can slide freely. I is a lever pivoted in the
bracket attached to the plate H; J is a screw passing through a screw threaded hole
in the opposite end of lever I, and bearing upon the plate H. The lever I is attached
to the feed hopper B, and by means of the screw J the said hopper together with the
positive electrode A attached to it, may be raised or lowered, to increase or decrease
the width of the zone of fusion as required, or to compensate for the wear of the
electrodes. K is a poker or plunger of carbon, placed within the hopper B, and
extending downwards through the electrode A nearly as far as the zone of fusion:
this poker is provided with projections K, for better acting upon the charge, and is
attached at its upper end to the crank of the driving shaft I, by means of the
connecting rod &¹. The driving shaft L is supported in any suitable bearings 1', and
is provided with a gear wheel 1, which engages with a similar gear wheel m of a
motor. As herein shown the motor consists of a weight m³, hung by the cord m
.carried by the drum m² the latter being secured to the shaft M and transmits the
power to the gear 12, through the gear m. A brake wheel m¹ is carried by the motor
shaft, and a crank handle m is provided for winding up the weight when the cord
is run down; instead of a weight and cord, a coiled spring or any other equivalent
mechanism may be used to operate the feed mechanism.
N is a brake lever pivoted at one end in the support n, and supported at the other
end N by means of the spring O, and screw o', which screw passes through a screw
.threaded hole in any suitable fixed support o'; by means of the screw of the tension
of the spring O can be regulated. The brake lever N is provided with a projection ²,
which engages with the serrations of the brake wheel m, when the brake lever is in
its raised position and locks the motor.
:.
P is an electro-magnet placed beneath the outer end of the brake lever. R and S
are the circuit wires attached respectively to the positive and negative electrodes and
the magnet P placed within the circuit.
The essential features of this furnace is, that the resistance is regulated and
preserved constant by the movement of the charge itself, and not by the movement
of the electrodes as at present practised; the action of the furnace is rendered
continuous for a long period, and the time lost in charging and emptying the furnace

page_text: as hitherto constructed is saved. The electrodes act as conductors only for conveying
the current to the charge and the heat is generated in the charge itself by its electrical
resistance, the carbon constituents of the charge becoming incandescent.
The practical operation of the furnace is as follows: The feed hopper is filled with
the material to be reduced, and the current is passed through the wires; this causes
an intense heat at the zone of fusion between the electrodes, the material is there
reduced, and falls through the lower electrode into the lower part of the furnace. The
electro-magnet P is made of just such a power that when the resistance at the zone of
fusion becomes less, and more than the normal amount of current flows through the
said magnet, the end of the brake lever will be drawn down against the tension of
the spring which supports it. This movement of the brake lever, sets free the brake
wheel, and the motor shaft is free to turn and by means of the driving shaft and
crank, to operate the poker in the furnace.
The movement of the poker up and down, forces more of the charge in the hopper
to descend into the zone of fusion and when the resistance is thereby increased to the
normal amount, the current which is proportionately decreased allows the electro-
magnet to let go the brake lever which then stops the movement of the poker. This
operation is again repeated upon fresh portions of the charge of material to be
reduced, which may consist of ore and carbon mixed together, or other equivalent
resistance material being fed downwards from the hopper, and the reduced metal·
withdrawn from the bottom.
It will be seen that with this form of furnace, the charcoal or carbon immediately
surrounding the zone of fusion renews itself as fast as it becomes graphitized; it then
falls down into the lower part of the furnace, or it may be knocked down by moving
the upper electrode, as it is desirable to get rid of it as soon as it becomes a good
conductor of electricity.
The invention is not confined to any specific form or construction of mechanism to
be employed, inasmuch as any mechanical devices may be used which can be actuated
and controlled primarily by the electrical resistance of the charge in the furnace, and
which will operate, through such agency, to control and govern the feeding of said
furnace.
It is well known that an electric lamp has been patented in which it was proposed
to obtain light from a stream of pulverized material caused to flow from a reservoir
through one pole of an electric circuit, and thence to the other pole, in contact with
the atmosphere and that it was proposed to regulate the exit valve of the reservoir
by means of an electro magnet placed in the circuit. The system of automatically
regulating the supply of resistance material between the poles of an electric circuit
by means of an electro-magnet device inserted in the circuit is not broadly claimed.
It is also known that an electric furnace has been constructed in which the length
of the are and the distance between the electrodes is automatically regulated by the
resistance of the arc.
Having now particularly described and ascertained the nature of the said invention,
and in what manner the same is to be performed as communicated to me by my
foreign correspondents I declare that what I claim is :-
1. In an electric furnace the combination of two stationary electrodes of opposite
polarity, a body of material which is a bad conductor of heat and electricity
surrounding the zone of fusion and a feed hopper for the charge to be reduced, and
means for automatically moving the charge between the said electrodes when the
normal resistance is diminished substantially as and for the purpose set forth.
2. In an electric furnace, the combination of two stationary electrodes of opposite
polarity, a body of material which is a bad conductor of heat and electricity
surrounding the zone of fusion, and a feed hopper for the charge to be reduced, a
device for moving the charge between the said electrodes, mechanism for actuating
the said charge moving device, and an electro-magnet placed in the circuit and
adapted to start the said actuating mechanism when the normal amount of the current
is increased, substantially as and for the purpose set forth.

page_text: 3. In an electric furnace, a hollow cylindrical electrode, a feed hopper attached to
one end of the said electrode, a lever pivoted to the stationary top portion of the
furnace for supporting the said feed hopper and electrode, and a screw for regulating
the position of the lever and causing the said electrode to project more or less within
the furnace, substantially as and for the purpose set forth.
4. In an electric furnace, the combination of two vertical electrodes of opposite
polarity, a lining of fine charcoal surrounding the lower electrode, a lining coarse
charcoal surrounding the zone of fusion between the electrodes and extending
upwards round the upper electrode, and the furnace walls for retaining the said
charcoal linings in position, substantially as and for the purpose set forth.
5. In an electric furnace, the combination of the electrodes A and C the feed.
hopper attached to electrode A, the poker working back and forth within the said
hopper and electrode, the driving shaft provided with a crank for actuating the said
poker and with the gear-wheel 1, the motor shaft M, provided with the means for
rotating it, the gear wheel m, and a brake wheel: the brake lever having. the.
projection m2, engaging with the brake wheel: the spring O attached to the said
brake lever at its free end, and the electro-magnet P for disengaging the brake
lever when the normal amount of current passing through the magnet is increased,
substantially as and for the purpose set forth.
6. Insan electric furnace, the combination of the retaining walls, the electrode C,
the fine charcoal lining F, the electrode A, the feed hopper B, the lining of coarse
charcoal G, the condenser t, the lever I pivoted at the top of the furnace for supporting
the said feed hopper and electrode A, and the screw J for adjusting the position of
the electrode A within the furnace, substantially as and for the purpose set forth.
7. An electric, furnace provided with a body of material which is a bad conductor
of heat and electricity, surrounding the zone of fusion and wherein the electrical
resistance of the charge while in the zone of fusion, constitutes the primary agency
whereby the feeding mechanism of the furnace is actuated and controlled, substantially
asiand for the purpose set forth.
8. An electrical furnace provided with a body of material which is a bad conductor
of heat and electricity surrounding the zone of fusion, and wherein the charge forms
part of an electric circuit and is in contact with the terminals of the electric circuit,
and wherein the varying electrical resistance of the said charge due to its temperature
and condition is the agency whereby the action of said furnace feeding or discharging
mechanism is actuated or controlled, substantially as and for the purpose set forth.
9. In an electrical furnace wherein the charge fills the space between the electrodes,
and is in contact therewith, the combination with suitable charging or feeding
apparatus of a body of material which is a bad conductor of heat and electricity
.surrounding the zone of fusion, and an electro-magnetic device actuated and controlled
by a. current dependent for its strength and variation upon the varying electrical
resistance of the charge in said zone of fusion substantially as and for the purpose
specified.
10. In an electrical furnace provided, with a body of material which is a bad
conductor of heat and electricity surrounding the zone of fusion, and wherein the
charge fills the space between the electrodes and is in contact therewith, an electric
circuit which includes the charge in said furnace and also includes suitable feeding
or charging apparatus or mechanism for controlling the same, whereby the electrical
resistance of the charge shall influence and govern the feeding, or charging of said
furnace, substantially as and for the purpose specified..