Improvements in Electric Furnaces for Manufacturing Calcium Carbide.
Year: 1898

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Furnaces for Manufacturing Calcium
Carbide.
A communication by CORYDON L. WILSON, CHARLES MUMA, JOHN W. UNGER, HENRY
SCHNECKLOTH, AMOS P. BROSIUS, and JOSEPH C. KUCHEL, all of Holstein, in the
County of Ida and State of Iowa, United States of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, 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
The object of this invention is to provide an electric furnace for reducing lime and
carbon, which furnace shall be of simple, durable and inexpensive construction, and
which may be rapidly and economically operated to produce a resultant product of
calcium carbide of comparatively great purity.
A further object is to provide a furnace of, this class in which lime and carbon
previously compressed into stick form may be fed by hand in any desirable quantity
and at the proper speed to produce the best results without subjecting the operator
to the dangers attendant upon a direct contact with the electrode through which the
lime and carbon is being fed.
This invention consists primarily in the construction of a hollow electrode having
at its upper end an insulator which is provided with openings to communicate with
the openings of the electrode, and the arrangement and combination therewith of
means for raising and lowering the electrode and insulator jointly so that the operator
may by hand feed sticks of lime and carbon into the are between the electrodes and
may also regulate the distance between the electrodes so that the proper distance may
be maintained at all times and the lime and carbon be fed to the are in the
proper quantities and at proper speed to produce the best results.
This invention consists further in the construction, arrangement, and combination
of the various parts of the furnace whereby the objects contemplated are attained, as
ereafter set forth and pointed out in the claims and illustrated in the accompanying
rawings, in which :
Figure 1 shows a perspective view of the complete furnace, with the top thereof
eld elevated.
Figure 2 shows a central vertical section of the furnace ready for operation.
Figure 3 shows a horizontal section of the furnace taken through the line 3—3 of

page_text: Figure 4 shows a horizontal sectional view through the line 4-4 on Figure 2.
Referring to the accompanying drawings the reference numeral 10 is used to
indicate a base for the furnace which is preferably made of brick. At its central top
portion is an electrode 11, which may be of any suitable material.
12 indicates a
pipe leading from the side of the furnace to the underside of said electrode, to serve
as a conduit for an electric cable 13, which leads from a dynamo or other source of
electrical supply to the electrode.
The reference numeral 15 is used to indicate a casing designed to rest on top of
the base and to enclose and contain the mixture of lime and carbon while it is being
reduced. This casing is divided vertically into two parts with hinges 16 at one side
and a latch 17, at the opposite side. By this means the casing may be opened to
discharge its contents of calcium carbide when finished. At its top is a central
opening 18, through which the movable electrode is entered as hereinafter described.
A number of openings 19 have been provided in this top covered by the slides 20,
through which access may be had to the interior of the casing from the top.
The reference numeral 21 is used to indicate the upper sliding electrode. This
is preferably composed of carbon and at its upper end portion is a metal band 22, to
which a cable 23 is connected and which leads to the dynamo or other source of
electrical supply 14. This electrode has a number of longitudinal openings 24,
extending entirely through it. It is preferred to construct this electrode out of a
number of carbons, each having a central opening and the whole held together by
cement or other substance of like character. This arrangement has been illustrated
in the drawings for the reason that this method has been found to be the most
practical from a commercial standpoint. However any kind of material for forming
this electrode may be used and one or more holes or openings extended therethrough
as desired. It is obvious that the construction of the hollow electrode may be varied
in many ways. However any shape of electrode through which a granular substance
may be fed would be the equivalent of the electrode shown.
At the top of this electrode is a metal collar 25, having two hooks 26, at opposite
sides thereof, and 27 indicates an extension of the electrode made of some material
which is a non-conductor of electricity but which is also provided with openings 28
which coincide with the openings in the electrode. The collar 25, serves to hold
this extension 27 to the electrodes and maintain their proper relative positions.
Means have been provided for raising the electrode and also the casing as follows:
The reference numeral 30 indicates a crane designed to be operated manually by means
of the crank 31, and having two cables 32 to pass over pulleys 33 which are located
at the outer end of the arm 34 of the crane. These cables are connected with the
hooks 26, and two additional cables 35 are connected with these hooks and with two
hooks 36 which are fixed to the opposite sides of the top of the casing. These cables
35 are of such a length that the electrode 21, will be drawn upwardly until its lower
end is near the top of the casing, before the said cables 35 will have reached their
limit. Hence the electrode is first drawn upwardly to its limit and further operation
of the crane will elevate the entire casing 15.
In practical operation a layer of previously made calcium carbide in granular form
is first placed on the top of the base and along the sides of the casing, as shown in
Figure 2, and indicated by the reference numeral 37. A number of sticks indicated
by the reference numeral 38 and which are composed of a mixture of lime and carbon
is then taken. These sticks are produced by first reducing lime and coal to a
powder, then commingling them in suitable proportions, and then placing the
mixture in suitable moulds where they are subjected to great pressure sufficient to
form the mixture into comparatively firm sticks. The sticks thus formed are placed
in the openings in the upper electrode and their lower ends rest upon
the lower electrode. In practical use the upper end of this upper electrode
is preferably separated from the furnace proper a considerable distance so that
a floor may be interposed between the operator and the furnace itself, thus
protecting the operator from the intense heat of the furnace. When the current of

page_text: electricity is turned on, it is obvious that an are is formed between the two electrodes,
and that the lime and carbon in this are will be subjected to intense heat and will
thereby be quickly melted. This molten product will obviously intermingle with the
granulated calcium carbide in the furnace and a body of molten calcium carbide will
5 be formed in the interior of the casing. This body of molten material forms itself
an excellent conductor of electricity and as it rises in the chamber the crane is
operated and the upper electrode is slowly elevated in order to maintain a proper
distance between the top surface of the molten material and the under surface
of the upper electrode, as required to form an electric arc.
until the interior of the casing has been filled as much as may be desired, whereupon
This process is carried on
the current is shut off and the crane operated still further to raise the casing 15 off
the base. The product may then slowly cool & may be removed in the usual
manner.
It is obvious that if desired the mixture of lime and carbon may be fed
through the openings in the upper electrode in a powdered form and the labour of
compressing the mixture into sticks or rods may be dispensed with.
It is obvious further that the operator may so regulate and control the supply of
lime and carbon to the arc as to utilize the maximum capacity of the arc at all times.
It is designed to have an electrical current of such a strength that when each of the
openings in the upper electrode is filled with the sticks of lime and carbon and the
electrodes separated about two inches, a perfect are will be produced and the lime and
carbon be melted as rapidly as possible. However a current of electricity will vary
in strength and the length of the arc will also be varied, hence the best results
cannot be produced by having each of the openings in the electrode filled with lime
and carbon at all times. With the electrode shown having a number of openings the
operator may vary the amount of lime and carbon contained in the arc at any one
time by feeding the sticks of lime and carbon through only a part of the holes. When
this is done all of the current of electricity will pass over or through the sticks of
lime and carbon that are placed in the arc and hence the full force of the current
will be passed through a less quantity of lime and carbon and hence the same will be
reduced as rapidly with a comparatively weak current as would a larger number of
sticks with a maximum current. Furthermore the operator is protected from the
possibility of contact direct with the electrical current by means of the block of
insulator at the top of the electrode.
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 by
my foreign correspondents, I declare that what I claim is:-
1. An electric furnace for producing calcium carbide, comprising a base, an
electrode mounted in the base, a second electrode slidingly supported above the base,
and having a number of longitudinal openings extended therethrough, a source of
electrical supply connected with the said electrode, a block of insulating material
fixed to the upper electrode, and also provided with a number of longitudinal openings
arranged to coincide with the openings in the electrode so that a number of sticks of
ime and carbon may be fed manually to the space between the electrodes, said upper
and lower electrodes being so arranged that the said sticks passed through the upper
electrode will rest upon the lower electrode until melted when they are free to run
rom between the electrodes, and means for raising and lowering the electrode and
nsulator jointly, substantially as and for the purposes stated.
2. An electric furnace for producing calcium carbide, comprising a base, an electrode
n the base, a source of electrical supply, a metal casing divided vertically into two
arts, a latch at the opposite side thereof from the hinges, a hook on each part,
lides hinged to the top of the casing to cover openings therein, an electrode having
ne or more vertical openings, a metal band at its top, an electric cable leading
herefrom to the said source of electrical supply, a metal collar at the upper end of
he electrode to the projection above it, hooks at the opposite sides thereof, cables

page_text: for connecting the said hooks with the aforesaid hooks on the casing, an insulator
resting in the said collar and having openings to coincide with the openings in the
electrode, a crane and two cables leading therefrom and to the said hooks in the
collar, all arranged and combined substantially as and for the purposes stated.
Dated this 28th day of March 1898.