Improvements connected with Electrical Furnaces.
Year: 1894

page_text: Date of Application, 23rd June, 1894
Complete Specification Left, 16th Mar., 1895-Accepted, 4th May, 1895
Improvements connected with Electrical Furnaces.
A communication from abroad by EDWARD GOODRICH ACHESON, Electrician,
of Main Street, Monongahela City, in the State of Pennsylvania, United
States of America.
1, PHILIP MIDDLETON JUSTICE, of 55 and 56 Chancery Lane, in the County
of Middlesex, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
This invention relates to electrical furnaces, and it has for its object to improve
the construction and arrangement of the mechanical parts of said furnace and also
to improve the arrangement of the materials supplied to the furnace, for the purpose
of utilizing the electric current more economically and producing more extensive
and satisfactory results and thereby to cheapen the product, as well as to improve
the same, and to these ends the invention consists in the various features of
construction and arrangement substantially as hereinafter more particularly
pointed out.
In the accompanying drawings, is illustrated the preferred construction and
arrangements of the furnace, and the materials supplied to the furnace, in which
Fig. is a side view, partially in section, of a furnace embodying my invention.
Fig. 2 is a vertical transverse section of the same.
Fig. 3 is a partial sectional view, showing another arrangement.
Fig. 4 is an end view of the same.
Fig. 5 is a partial sectional view of still another arrangement;
Fig. 6 is an end view of the same, and
Fig. 7 is a detail.
While the furnace is adapted for use in various electro-metallurgical operations
and while it is not limited to the production of any one material, it is more especially
adapted for the production of what is known as "carborundum," a material which
is the invention of my correspondent and the subject of Letters Patent No. 17,911
of 1892, and it is here shown as adapted to such use, the invention being hereafter
described in this connection.
One of the objects of the invention is to provide a furnace wherein the electric
current is restricted to a great extent to a well-defined path or core in its passage
through the furnace, while the material to be treated and operated upon is so
placed or arranged in the furnace as to receive the heat energy from the core
in lines diverging from the direction of the path of the electric current, in contra-
distinction to those furnaces in which the materials being operated upon are inter-
mingled with the electric conducting medium, and are operated upon more or less
directly, the heat energy in this case being produced in immediate contact with and
through the mass of material being treated. Another distinguishing feature of the
invention resides in the fact that the core forming the path for the electric current,
while offering a greater or less resistance to the passage of the current so that it
will become sufficiently heated, is of relatively lower resistance to the electric
current than the resistance of the materials treated, so that not only does the core
form a more direct path for the passage of the electric current, but a path of less
resistance, so that practically a very small portion, if any, of the current diverges
from the path and passes through the material being operated upon. Other features

page_text: of the invention relate to the mechanical construction of the parts, resulting in
some instances from the features above mentioned, and contributing to the more
economical and direct use of the current and resulting in more successful operation-
of the furnace.
The formace comprises a receptacle, which may be of any desirable form, bu
preferably of relatively great dimensions in the direction of the path of the curren:
compared to its cross-section, and is built up of some refractory material, which
also electrically non-conducting, as for instance, fire-brick. There is shown in
the drawing a base A. forming a solid foundation, upon which is erected the
receptacle, having the sides A' and ends A. These side walls A' are constructed
in a manner to form loose joints between the brick or other material composing the
walls, in order to permit the free escape of gases resulting from the operations, the
gases burning at these points of escape art thereby contributing to a greater or
less extent to the heating of the materials operated upon. The end walls are
arranged to furnish a bearing for the electrodes, and these may be variously con-
structed in accordance with the particular form of electrodes used. Thus, for
instance, in Figs. 1 and 2, 1 have shown an electrode comprising a number of
carbon rods 1, passing through openings in the end of the furnace, which openings
are lined, as at a, with some highly refractory material, as asbestos or the like.
The unter emils of these rods are connected together electrically in any suitable way.
us by a terminal plate B', to which the conductor leading from the source of electric
energy S, is connected in any suitable way, the object being to distribute the
electric energy throughout all the rods as evenly as possible, and to provide a large
area of contact between the core and the electrodes in the interior of the furnace.
In the form shown in Figs. 3 and 4, in place of a number of carbon rods, there is
shown a single terminal in the form of a plate or block of carbon or similar con-
ducting material, which is connected to the source of supply in a similar manner.
A preferable construction of electrodes is shown in Figs. 5 and 6 wherein practically
the whole end of the furnace is comprised in the electrode B. This electrode is
composed in the present instance of a number of rectangular bars of carbon
arranged in a suitable confining frame or clamp B2, which in this instance comprises
the metallic bars or plates connected by screw rods, whereby the various
carbon rods may be held in close contact with each other. In order to supply the
current to these rods with the least possible resistance and to evenly and thoroughly
distribute it throughout the mass of the rods, a series of plates B, is made use of
preferably of copper, which are placed between the successive layers of bars, and
are held in intimate contact with the faces of the bars by the frame B, and for
convenience of connecting the electric terminals therewith, these plates are provided
with tongues or extensions, which can conveniently be brought together, as
clearly seen in Fig. 6, and secured to the terminal conductor so that it shall offer
little resistance to the passage of the current, and shall thoroughly distribute it
throughout the mass of the electrode. The electrodes at each end of the furnace
have practically the same arrangement, only one being shown in detail in the
drawing.
In preparing the furnace for operation a path for the passage of the electric
current is provided through the furnace, and it is shown in the form of a core C.
This core is composed primarily of some refractory material which oflers a greater
or less resistance to the passage of the current, but which is of a lower resistance
than the mass of material being operated upon, and while various substances may
be used as a core and it may be in a solid mass or in a granular condition, granular
carbon is preferably used the size of the individual grains varying in accordance
with the size of the furnace and the conditions of the current being used. For
instance, in a furnace where the core is about eight feet in length, and the maximum
value of the energy of the current approximately 100,000 watts the diameter of
the core being approximately ten inches, the individual grains composing the core
are preferably about three-sixteenths of an inch in diameter. It will be understood
that the invention is not limited to these precise dimensions in connection with this

page_text: amount of electric energy, but practice has demonstrated that these proportion
most effective.
Carbon in its various forms may be used as a core, and the relative sizes and
dimensions of the core will vary in accordance with the character of the carbon and
its electrical conductivity. For instance, in forming a core of granulated coke of
the standard quality, made from bituminous coal, the core is made substantially
of the dimensions stated, and it has been found that after once using, the
character of the grains has become changed in the matter of form and electrical
conductivity, to such an extent as to render it desirable to form the core when
constructed of these altered grains of a smaller diameter than when made of the
original coke.
While the core as above described may extend throughout the length between
the electrodes, it is preferable to reduce the size of the particles forming the core
at its ends to improve the contact between the core and the electrodes, making
more intimate contact with the electrodes and aiding in the ready passage of the
current through the core, and there is for this purpose shown at e, a portion of the
particles of the core in a reduced condition.
core.
Moreover, it is exceedingly important to prevent the material to be treated
coming in contact with the electrodes, in order to avoid the formation of incrustations
on the electrodes, which interfere with the free passage of the electric current, and
with this object in view the inner ends of the electrodes enter into the body of the
In order to aid in maintaining intimate contact between the particles of the
core and the electrodes, a weight W, is sometimes applied as indicated in Fig. 1, or
the same results are accomplished to a greater or less extent by arranging the
electrodes in the position indicated in Fig. 3, where the weight of the mass tends
to maintain intimate contact and where it will be seen that the core C is not entirely
surrounded by the mass of material.
Arranged in the furnace and surrounding the core is the mass of materials to be
treated, by being subjected to the influence of the intense heat generated in the
core by the passage of the electric current, and this mass is indicated at D. Or
course, it will be understood that this mass will vary in its composition according
to the purposes and objects for which the furnace is used and the products to be
obtained, and in the present instance in which the furnace is used in the production
of carborundum, this mass comprises a mixture of some carbonaceous material,
asilicious material, a suitable fluxing material, and a substance which will add to
the electrical resistance of the mass, while it acts to render the mass more porous,
Thus, a preferred
and to aid in the escape of the gases throughout the mass.
mixture for the production of carborundum comprises twenty parts by weight of
cual, coke or other form of carbon reduced to small particles, twenty-nine parts of
sand, five parts of common salt, and a sufficient quantity of fibrous material, such
for instance as saw-dust, cork, or the like, in about two parts by weight. These
materials are intimately mixed together and are packed in the furnace so as to
surround the core practically throughout its length.
Generally the mass is placed directly in contact with the surface of the core,
Lut in some instances means may be interposed to separate the core from the mass,
such for instance, as layers of paper or similar material, but these of course, are
destroyed in the ordinary operation of the furnace.
It has been found exceedingly advantageous to use as a carbonaceous material, a
hydrocarbon, such for instance, as anthracite coal, as this is not only exceedingly
cheap, but it is rich in carbon, and the parts which would ordinarily be a waste, in
carrying out my process, in this case are utilised as a fuel to aid in heating the
mass, thereby reducing the electric energy necessary to produce any given amount
of product.
as nearly
From the above it will be seen that the charge of the furnace comprises as its
essentials a conducting core between the electrodes, which core is
elementary in its composition as possible, that is, it should be (when carbon is used)
as pure carbon as can be readily obtained, and it should be in a form to offer le s

page_text: resistance to the passage of the electric current than the surrounding material to
be operated on, and at the same time it should be capable of being bented to an
intense degree without destruction. It is also well understood that in producing a
crystalline product, it is necessary to have some base on which the crystals can
commence to form, and in the electro-metallurgical formation of crystals which in
this case is contemplated, the laws governing the formation of crystals are not
departed from, and the core forms the necessary groundwork for the growth of the
crystals, which are formed in a ring or cylinder around the ass of the core, the
nature of the constituents of the original mixture being destroyed as the crystalline
ylinder increases in its dimensions.
Thus, in the operation of the furnace it will be seen that the electric current
passes through the core connecting the electrodes, and it is necessary to the
successful operation that practically all of the current should be conducted through
the mass of the core, as the passage of the current or any part thereof through
the mixture of the materials is detrimental to the production of the crystalline
products, and when any material amount of current does pass through the mixture.
the successful production of crystals is prevented.
It will be seen that the core becomes heated to a high degree of temperature by
the passage of the current, and the heat therefrom is imparted to the surrounding
mass of material in lines diverging from the lines of the current through the core,
and as before intimated, the combustion of the gases, and to some extent the
carbon in the mixture in that portion of the charge exposed to the air, aids in
heating the mass, and thereby hastening the process and producing a saving in the
amount of electric energy expended for a given output.
Dated this 23rd day of June 1894.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicant.
A communication from abroad by EDWARD GOODRICH ACHESON, Electrician.
of Main Street, Monongahela City, in the State of Pennsylvania, United
States of Americn.
I, PHILIP MIDDLETON JUSTICE of 55 and 56 Chancery Lane in the County
of Middlesex, Chartered Patent Agent, 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 electrical furnaces, and it has for its object to improve
the construction and arrangement of the mechanical parts of said furnace and also
to improve the arrangement of the materials supplied to the furance, for the
purpose of utilizing the electric current more economically, and producing more
extensive and satisfactory results, and thereby to cheapen the product as well as to
improve the same, and to these ends the invention consists in the various features
of construction and arrangement substantially as hereinafter more particularly
pointed out.
In the drawings accompanying the Provisional Specification is illustrated the
preferred constructions and arrangements of the furnace, and the materials supplied
to the furnace, in which :-
.
Fig. 1 is a side view, partially in section, of a furnace embodying the invention.
Fig. 2 is a vertical transverse section of the same.
Fig. 3 is a partial sectional view showing another arrangement.

page_text: Fig. 5 is a partial sectional view of still another arrangement.
Fig. 6 is an end view of the same: and
Fig. 7 is a detail.
While the furnace is adapted for use in various electro-metallurgical operations
and while it is not limited to the production of any one material, it is more
"carborundum," a
especially adapted for the production of what is known as
material which is the invention of my correspondent, and the subject of Letters
Patent No. 17911 of 1892, and it is here shown as adapted to such use, the
invention being hereafter described in this connection.
One of the objects of the invention is to provide a furnace wherein the electric
current is restricted to a great extent to a well defined path or core in its passage
through the furnace, while the material to be treated and operated upon is so
placed or arranged in the furnace as to receive the heat energy from the core in
lines diverging from the direction of the path of the electric current, in contra-
distinction to those furnaces in which the materials being operated upon are
termingled with the electric conducting medium, and are operated upon more or
less directly, the heat energy in this case being produced in immediate contact with
and through the mass of material being treated. Another distinguishing feature
of the invention resides in the fact that the core forming the path for the electric
current, while offering a greater or less resistance to the passage of the current so
that it will become sufficiently heated, is of relatively lower resistance to the
electric current than the resistance of the materials treated, so that not only does
the core form a more direct path for the passage of the electric current but a
path of less resistance, so that practically a very small portion, if any, of the
current diverges from the path and passes through the material being operated
Other features of the invention relate to the mechanical construction of
the parts, resulting in some instances from the features above mentioned, and
contributing to the more economical and direct use of the current and resulting in
more successful operations of the furnace.
upon.
The furnace comprises a receptacle, which may be of any desirable form, but
preferably of relatively great dimensions in the direction of the path of the
current compared to its cross-section, and is built up of some refractory
aterial which is also electrically non-conducting, as for instance firebrick. There
is shown in the drawing a base A, forming a solid foundation upon which is erected
the receptacle having the sides A' and ends A. These side walls A' are
constructed in a manner to form loose joints between the brick or other material
composing the walls in order to permit the free escape of gases resulting from
the operations, the gases burning at these points of escape and thereby contributing
to a greater or less extent to the heating of the materials operated upon. The end
walls are arranged to furnish a bearing for the electrodes, and these may be
variously constructed in accordance with the particular form of electrodes used.
Thus for instance in Figs. 1 and 2 there is shown an electrode comprising a number
of carbon rods B passing through openings in the end of the furnace, which
openings are lined, as at a with soine highly refractory material as asbestos or the
like. The outer ends of these rods are connected together electrically in any
suitable way, as by a terminal plate B', to which the conductor leading from the
source of electric energy S, is connected in any suitable way, the object being to
distribute the electric energy throughout all the rods as evenly as possible, and to
provide a large area of contact between the core and the electrodes in the interior
of the furnace.
In the form shown in Figs. 3 and 4 in place of a number of carbon rods
there is shown a single terminal in the form of a plate or block of carbon or
similar conducting material, which is connected to the source of supply in a similar
A preferable construction of electrodes is shown in Figs. 5 and 6 wherein
practically the whole end of the furnace is comprised in the electrode B2. This
electrode is composed in the present instance of a number of rectangai ir bars of
manner.

page_text: carbun 6ª, arranged in a suitable confining frame or clump 133, which in this
instance comprises the metallic bars or plates, connected by screw rods
whereby the various carbon rods may be held in close contact with each other.
In order to supply the current to these roils with the least possible resistance
and to evenly and thoroughly distribute it throughout the mass of the rods, a
series of plates B is made use of preferably of copper, which are placed between
the successive layers of bars, and are held in intimate contact with the faces
f the bars by the frame B, and for convenience of connecting the electric
terminals there with, these plates are provided with tongnes or extensions
which can conveniently be brought together, as clearly seen in Fig. 6, and secured
to the terminal conductor so that it shall offer little resistance to the passage of
the current, and shall thoroughly distribute it throughout the mass of the electrode.
The electrodes at each end of the furnace have practically the same arrangement,
only one being shown in detail in the drawing.
In preparing the furnace for operation a path for the passage of the electric
current is provided through the furnace, and it is shown in the form of a core C.
This core is composed primarily of some refractory material which offers a greater
or less resistance to the passage of the current, but which is of a lower resistance
than the mass of material being operated upon, and while various substances may
be used as a core and it may be in a solid mass or in a granular condition, granular
carbon is preferably used the size of the individual grains varying in accordance
with the size of the furnace and the conditions of the current being used. For
instance, in a furnace where the core is about eight feet in length, and the maximum
value of the energy of the current approximately 100,000 watts the diameter of
the core being approximately ten inches, the individual grains composing the core
are preferably about three-sixteenths of an inch in diameter. It will be understood
that the invention is not limited to these precise dimensions in connection with this
amount of electric energy, but practice has demonstrated that these proportions
are most effective.
Carbon in its various forms may be used as a core, and the relative sizes and
dimensions of the core will vary in accordance with the character of the carbon and
its electrical conductivity. For instance, in forming a core of granulated coke of
the standard quality, made from bituminous coal, the core is made substantially
of the dimensions stated, and it has been found that after once using, the character
of the grains has become changed in the matter of form and electrical conductivity.
to such an extent as to render it desirable to form the core when constructed of
these altered grains of a smaller diameter than when made of the original coke.
While the core as above described may extend throughout the length between
the electrodes, it is preferable to reduce the size of the particles forming the core
at its ends to improve the contact between the core and the electrodes, making
more intimate contact with the electrodes and aiding in the ready passage of the
current through the core, and there is for this purpose shown at e, a portion of the
particles of the core in a reduced condition.
the core.
Moreover, it is exceedingly important to prevent the material to be treated
coming in contact with the electrodes, in order to avoid the formation of incrusta-
tions on the electrodes, which interfere with the free passage of the electric current,
and with this object. view the inner ends of the electrodes enter into the body of
In order to and in maintaining intimate contact between the particles of
the core and the electrodes, a weight. W is sometimes applied as indicated in Fig. 1,
or the same results are accomplished to a greater or less extent by arranging the
electrodes in the position indicated in Fig. 3, where the weight of the mass tends
to maintain intimate contact, and where it will be seen that the core C is not
entirely surrounded by the mass of material.
Arranged in the furnace and surrounding the core is the mass of materials to be
treated, by being subjected to the influence of the intense heat generated in the
core by the passage of the electric current, and this mass is indicated at D. Of
course, it will be understand that this mass will vary in its composition according

page_text: to the purposes and objects for which the furnace is usel and the products to be
obtained, and in the present instance in which the furnace is used in the production
of carborundum, this mass comprises a mixture of some carbonaceous material, a
silicious material, a suitable fluxing material, and a substance which will add to th:
electrical resistance of the mass, while it acts to render the mass more porous, an
to aid in the escape of the gases throughout the mass. Thus, a preferred mixture
for the production of carborundum comprises twenty parts by weight of coal, coke
or other form of carbon reduced to small particles, twenty-nine parts of sand, five
parts of common salt, and a sufficient quantity of fibrous material, such for instance
as saw-dust, cork, or the like, in ab ut two parts by weight. These materials art
intimately mixed together and are packed in the furnace so as to surround the core
practically throughout its length.
Generally the mass is placed directly in contact with the surface of the
core, but
in some instances means may be interposed to separate the core from the mass, such
for instance, as layers of paper or similar material, but these of course, are
destroyed in the ordinary operation of the furnace.
It has been found exceedingly advantageous to use as a carbonaceous material,
a hydro-carbon, such for instance, as anthracite coal, as this is not only exceedingly
cheap, but it is rich in carbon and the parts which would ordinarily be a waste in
carrying out my process, in this case are utilized as a fuel to aid in heating the
mass, thereby reducing the electric energy necessary to produce any given amount
of product.
1.
From the above it will be seen that the charge of the furnace comprises as its
essentials a conducting core between the electrodes, which core IG as nearly
elementary in its composition as possible, that is, it should be (when carbon is used)
as pure carbon as can be readily obtained, and it should be in a form to offer less
resistance to the passage of the electric current than the surrounding material to be
operated on, and at the same time it should be capable of being heated to an intense
degree without destruction. It is also well understood that in producing
crystalline product, it is necessary to have some base on which the crystals cau
commence to form, and in the electro-metallurgical formation of crystals which in
this case is contemplated, the laws governing the formation of crystals are not
departed from, and the core forms the necessary ground-work for the growth of the
crystals, which are formed in a ring or cylinder around the mass of the core, the
nature of the constituents of the original mixture being destroyed as the crystalline
cylinder increases in its dimensions.
Thus, in the operation of the furnace it will be seen that the electric current
passes through the core connecting the electrodes, and it is necessary to the
successful operation that practically all of the current should be conducted through
the mass of the core, as the passage of the current or any part thereof through the
mixture of the materials is detrimental to the production of the crystalline
products, and when any material amount of current does pass through the mixture,
the successful production of crystals is prevented.
It will be seen that the core becomes heated to a high degree of temperature by
the passage of the current, and the heat therefrom is imparted to the surrounding
mass of material in lines diverging from the lines of the current through the core,
and as before intimated, the combustion of the gases, and to some extent the carbon
in the mixture in that portion of the charge exposed to the air, aids in heating the
mass, and thereby hastening the process and producing a saving in the amount of
electric energy expended for a given out-put.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad by my foreign correspondent, I declare that what I claim is :-
:―
1. In an electric furnace, the combination with the electrodes, of a core of
relatively low resistance, and a mass of material to be operated upon and of greater
resistance surrounding the core, substantially as described.

page_text: 2. In an electric furnace, the combination with the electrodes, of a mass of
material to be operated upon, and a conducting path for the electric current through
the body of the mass, substantially as described.
3. In an electric furnace, the combination with the walls of the furnace and the
electrodes, of a conducting path of refractory material for the electric current, and
is mass of material to be operated upon surrounding the path, the walls of the
furnace being constructed to permit the free escape of the gases from the mass,
substantially as described.
4. In an electric furnace, a mass to be treated comprising a carbonaceous
material, a silicious material, a flux and a fibrous material, substantially as
described.
5. In an electric furnace, a mass to be treated comprising anthracite coal, sand,
salt, and a non-conducting material, substantially in the proportions set forth.
6. In an electric furnace, the combination with a conducting core or path for the
electric current, having its end portions in a fine or reduced condition, of the
electrodes in intimate contact with said end portions of the core, and a mass of
material to be operated upon above the core and adapted to be heated by the beat
generated by the passage of the current through said core, substantially as
described and illustrated in Figures 3 and 4.
7. In an electric furnace, a mass to be treated, meaus for heating the mass
interiorly by the heat produced by the passage of an electric current, the walls
being arranged to be heated exteriorly by the combustion of a part of itself,
substantially as described.
8. In an electric furnace, an electrode comprising bars of conducting material,
interposed plates of conducting material having projections connected together to
form a terminal, and a clamp embracing the bars, substantially as described and
illustrated in Figures 5 to 7.
Dated this 15th day of March 1894
PHILIP M. JUSTICE.