Year: 1899

page_text: Date of Application (in United Kingdom), 21st June, 1899
Complete Specification Left. 17th Feb., 1900-Accepted, 31st Mar., 1900
Date of Application (in United Kingdom), 21st June, 1899
Complete Specification Left. 17th Feb., 1900-Accepted, 31st Mar., 1900
We, LA COMPAGNIE ELECTRO-MÉTALLURGIQUE DES PROCÉDÉS GIN ET LELEUX, of
28, Rue de St. Petersburg, Paris, in the Republic of France, do hereby declare
the nature of this invention to be as follows:
This invention relates to improvements in electric furnaces of the kind more
especially intended, for the manufacture of carbide of calcium and has for its
object to improve the working of the same and to increase their yield.
"
The improvements hereinafter described relate more especially to furnaces
known as resistance" furnaces comprising a vertical electrode capable of a rising
and falling movement, adjustable at will and a crucible or melting pot with a
fixed hearth or bed-plate constituting the second electrode and serving for the
return of the current. The crucible is mounted on a carriage or suspended from
travelling pullies.
In ordinary furnaces with carbons of high conductivity the heat developed by
the passage of the current or transmitted by the heat from the hearth is frequently
sufficient to raise the electrodes to a red heat and cause their rapid destruction
by combustion in the air.
To overcome this objection the upper electrode according to this invention is
formed of one or more cores of carbon of high electric conductivity, for example
an electrode with four cores square in section may be used but the number and
the sectional form of the cores may be varied. These cores are surrounded by a
mass of carbon agglomerated by means of oil tar, which mass is obtained by crush-
ing the material and roasting in a muffle furnace at a temperature not exceeding
1000 degrees. An electrode is thus formed with an increased external surface
whereby its cooling is facilitated by the surrounding air, while the superficial
material of the electrode has a comparatively low conductivity so as to protect
the cores from the furnace heat; the surface of the material is kept at a tem-
perature below that which is necessary for the combustion of the carbon, which
is a great advantage, the electrode being maintained cool by the current of air
entering from outside the furnace and drawn in by the draught from the chimney
while from the temperature of the hearth the lower portions of the electrode
acquire perceptibly the same electric conductivity so that the current spreads
over the whole section.

page_text: The other electrode is formed by the bed of the furnace; it is arranged to facili-
tate the flow of the product, for example; carbide of calcium, by localizing and
concentrating the calorific action of the current opposite the discharge holes.
With this object in view the bed is formed in two parts separated by a layer of
insulating material such as concrete (of lime or magnesium for example) of a
sufficiently refractory nature and a poor conductor of heat. The two superposed
parts forming the furnace bed are connected by blocks of carbon of relatively
small section and situated immediately adjacent to the outlet or discharge holes.
The passage of the electric current through these carbons maintains at this part
a higher temperature than over the rest of the bed of the furnace thus facilitating
the flow of the carbide.
The furnace bed is supported on a carriage which is made separate from the
bed and merely acts as a support, and is enclosed in a casing con-
stituting the crucible which IS preferably of metal provided with
perforations for dividing the gases which form the rein, into thin
streams, which are collected in channels formed in the walls of the
furnace communicating with the draught chimney, the formation of large bodies
of explosive gases being thus prevented. These gases, which in the case of
carbide of calcium consist chiefly of carbonic oxide combine with the oxygen in
the air, keeping a temperature round the crucible such that it is possible to restrict
the outflow of heat from the crucible and thus prevent waste. The connections
between the electrodes and the conductors which bind them to the pole of the
source of electricity will now be explained.
In the case of the vertical electrode the current enters by an upper conductor
passing thence by cables to an armature formed of plates corresponding in number
to the aforesaid carbon cores in the electrode; the said electrode may be raised
and lowered by a fly wheel and chain and pullies. Over the two internal faces
of each of the carbons a continuous elastic pad is applied formed of thin plates
of red copper which may be silvered; the plates are applied to one side of each
pad and kept in position by means of wedges and keys with screw heads. By
tightening up the screw head the simultaneous locking of the two plates on the
corresponding carbons is thus secured. A similar arrangement is employed to
obtain perfect contact between the carbons and that portion of the pad over the
faces of which there are no plates. Bolts passing through the two carbons and
the two plates ensure a good connection between the electrode on the one hand
and the armature formed by the plates on the other hand.
This arrangement for connecting the parts together has the advantage of pre-
venting any disarrangement of the parts which might arise from unequal expan-
sion of the carbon and the metal forming the leads.
The other connection for connecting the bed of the furnace with the other pole
of the source of electricity is obtained automatically by merely placing the car-
riage with the bed plate thereon in its proper position.
The metal frame of the carriage is insulated from the axles and the wheels.
On the floor of the carriage a plate of copper is placed on which a yielding pad or
mattress formed of cables rests. The weight of the bed ensures good electric
contact between the elements of the said furnace bed and the aforesaid metallic
part to the end of which a wedge is fixed in any suitable manner.
The conductor starting from the second pole of the source of electricity is
divided before reaching the wall of the furnace and is firmly united to the arms
of a conducting part or bracket mounted thereon to which part are attached
brushes constituting spring contacts. The bed plate is placed in circuit by
causing the wedge projecting from the end thereof to enter between the aforesaid
brushes forming the spring contacts:
D
31
T
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents,

page_text: We, LA COMPAGNIE ELECTRO-MÉTALLURGIQUE DES PROCEDES GIN ET LELEUX, of.
28, Rue de St. Petersburg, Paris, in the Republic of France, 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 improvements in electric furnaces of the kind more
especially intended for the manufacture of carbide of calcium and has for its
object to improve the working of the same and to increase their yield.
And in order that our invention may be clearly understood we will describe the
same in detail with reference to the accompanying drawings in which
Figure 1 is a longitudinal section of a furnace constructed according to our
invention, Figure 2 is a transverse section of the same; Figures 3 and 4 shew on
a larger scale the method adopted for connecting one of the electrodes with one
of the electric conductors or leads. Figures 5, 6 and 7 show in detail the means.
employed for connecting the other electrode with the other lead.
The improvements hereinafter described relate more especially to furnaces known
as resistance furnaces and comprises an electrode capable of vertical movement,
and adjustable at will, and a crucible or melting pot with a hearth or bed plate
constituting the second electrode and serving for the return of the current. The
crucible may be mounted on a carriage or be suspended from travelling pullies.
In ordinary electrical furnaces with carbons of high conductivity the heat deve-
loped by the passage of the current or transmitted by the heat from the hearth is.
frequently sufficient to raise the electrodes to a red heat and cause their rapid
destruction by combustion in the air.
To overcome this objection the upper electrode according to this invention is
formed of one or more carbon cores a. of high electric conductivity; in the draw-
ings we have shewn by way of example an electrode with four cores, square in
section, but it will be understood that the number and the sectional form of the
cores may be varied. These cores are surrounded by a mass of carbon agglo-
merated by means of oil tar. The agglomerated mass may be obtained by crush-
ing the material and roasting it in a muffle furnace at a temperature not exceed-
ing 1000 degrees Centigrade. An electrode is thus formed with an increased
external surface whereby its cooling is facilitated by the surrounding air, while
the superficial material of the electrode has a comparatively low. conductivity
so as to protect the cores from the furnace heat. The surface of the material
is kept at a temperature below that which is necessary for the combustion of
the carbon, which is a great advantage, the electrode being maintained cool
by air entering, as shewn by arrows, from outside the furnace, the said air being
drawn in by the draught of the chimney while from the temperature of the
hearth all parts of the lower portions of the said electrode acquire the same
electric conductivity so that the current spreads over the whole of the said lower
portion of the said electrode.
The other electrode is formed by the bed of the furnace, which bed is arranged
so as to facilitate the flow of the product; for example carbide of calcium, by
localizing and concentrating the calorific action of the current opposite the dis-
charge holes d.
With this object in view the bed is formed in two parts ee separated by a
layer of insulating material such as concrete of a sufficiently refractory nature
and a poor conductor of heat, such for example as lime or magnesia. The two
superposed parts c'e¹ forming the furnace bed are connected by blocks of carbon g

page_text: of relatively small section and arranged immediately adjacent to the outlet or
discharge holes d. The passage of the electric current through the carbons g
maintains at this part a higher temperature than over the rest of the bed of the
furnace, thus facilitating the flow of the carbide.
The furnace bed is supported on a carriage h which is made separate from the
bed and merely acts as a support therefor. The said furnace bed is enclosed in a
casing containing the crucible i which is preferably of metal provided with per-
forations for dividing the gases, which form therein, into thin streams, which are
collected in channels k formed in the walls of the furnace and communicating
with the chimney c, the formation of large bodies of explosive gases being thus
prevented. These gases, which in the case of carbide of calcium consist chiefly
of carbonic oxide, combine with the oxygen in the air drawn in, and keep the
temperature round the crucible such that it is possible to restrict the loss of heat
from the crucible and thus prevent waste.
The connections between the electrodes and the conductors with the source of
electricity are as follows:
In the case of the electrode ab which is connected to one pole of the source
of electricity the current enters by the leads m pasing thence by cables n to a
conductor formed of plates ? corresponding in number to the number of cores a
in the electrode; which electrode may be raised and lowered by means of a chain,
as shewn, passing round pullies and connected to a winding device o. Figures 3
and 4 shew the manner of connecting the plates to the carbons a.
Over the two internal faces of each of the carbons (t. is applied a
thin plate of red copper, which may be silvered, against which copper plates
the plates are applied and kept in position by means of wedges and keys s
the said keys being provided with screws on which nuts are screwed and by
means of which nuts the keys s can be caused to force the wedges against the
plates on the adjacent faces of two contiguous carbons a thereby simultaneously
locking the two plates p against the said carbons. A similar arrangement is
employed to obtain perfect contact between the contiguous faces of the carbons a
on which portions of the copper plates q bear, but over the faces of which there
are no plates. Bolts are passed horizontally through each two contiguous
carbons, to which the plates are attached, through which plates the said bolts
also pass so as to ensure a good connection between the electrode on the one hand,
and the conductor formed by the plates on the other hand.
This arrangement for connecting the parts together has the advantage of pre-
venting any disarrangement of the parts which might arise from unequal expan-
sion of the carbon and the metal forming the leads.
The connection of the bed of the furnace with the other pole of the source of
electricity is obtained automatically by merely placing the carriage with the
furnace bed thereon in working position as shewn in Figures 5, 6 and 7.
The metal frame h of the carriage is insulated from the axles and the wheels.
On the floor of the carriage is placed a plate of copper on which is placed a
yielding pad or mattress w formed of cables. The weight of the bed ensures good
electric contact between the elements e and g of the furnace bed and the metallic
part h, v, of the carriage to which is fixed a wedge æ for entering between spring
contacts j.
The lead m starting from the second pole of the source of electricity is divided
or forked just before it reaches the wall y of the furnace and is connected by bolts
or otherwise to the arms of a conducting piece to which are attached laminated
brushes constituting the spring contacts j. The bed of the furnace is placed in
circuit by causing the wedge to enter between the spring contacts j.
Having now particularly described and ascertained the nature of this invention,
and in what manner the same is to be performed, we declare that what we
claim is:
-
1. In an electric furnace the use of electrodes formed by one or more cores of

page_text: carbon of high conductivity surrounded by an agglomerated mass of roasted carbon
so as to avoid superficial combustion and reduce the wear of the electrodes, sub-
stantially as hereinbefore described.
2. In an electric resistance furnace a bed plate made of two superposed parts
separated by an insulating layer of refractory material, the two parts being placed
in communication by carbon blocks arranged adjacent to the discharge holes
sc as to concentrate the heat at the part where the metal is discharged sub-
stantially as herein before described.
3. In an electric resistance furnace the use of a crucible having perforations
therein for dividing the generated gases into streams which enter channels, in the
walls of the furnace, in which they mix with air and so maintain around the
crucible a regulated temperature and restrict calorific emission and consequently
the loss of heat whilst the air admitted maintains cool the external surface of the
electrodes, substantially as herein before described.
4. In an electric resistance furnace the arrangement of wedges and keys for
connecting the adjustable electrode to the conducting plates in connection with
the source of electricity substantially as hereinbefore described.
5. In an electric resistance furnace a bed plate provided with a wedge arranged
to enter between spring contacts so as to complete the electric circuit when the
said bed is placed in working position substantially as hereinbefore described.
6. The combination and arrangement of parts constituting the electric furnace
substantially as hereinbefore described and illustrated by the accompanying
drawings.
n: 17th dass of Wabunt 1900
JOHNSONS & WILLCOX;
47, Lincoln's Inn Fields, London, W.C., Agents.