Improvements in Apparatus for Electrochemical and Electrothermic Melting Operations, especially for the Production of Calcium Carbide.
Year: 1899

page_text: Date of Application, 18th Aug., 1899
Complete Specification Left, 15th Apr., 1900-Accepted, 4th Aug., 1900
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Electrochemical and Electrothermic
Melting Operations, especially for the Production of Calcium
Carbide.
I, EMIL GRAUER, Director of Factory, and Chemist, of Lauffen on the Neckar,
in the Empire of Germany, do hereby declare the nature of this invention to
be as follows:-
It is known that in connection with electrochemical and electrothermic
melting operations, metal plating, reductions, production of chemical compounds
such as carbides and the like operations the success of the process, or in other
words, the nature of the product, is dependent upon a number of circumstances,
especially upon the piece of work, or the material to be worked being uniformly
introduced between the electrodes, exposed for a certain time to the action of
the current in certain cases constant, and then quickly and uniformly removed
from the circuit, so as to avoid any subsequent injurious action of the current.
The object of this invention is to provide an apparatus by means of which these
conditions of working, which are not fulfilled, or only imperfectly fulfilled with
the electrical furnaces hitherto constructed can be easily met and further-
which is especially important-can be regulated easily and independently of
cach other so that, according to the nature of the raw material, or piece of work
to be dealt with and the quality of the product which it is desired to obtain,
the period of treatment, the quality of the material to be treated, the quickness
of the introduction to and removal from the current circuit, and the distribu-
tion in regard to space and the placing of the material between the electrodes
can be most accurately determined. From this it follows at the same time
that it is also possible to keep within certain limits the effective electrical
resistance which is partially dependent upon the factors mentioned and to pre-
vent or considerably to lessen injurious variations of the working current, as
well as the loss of current arising therefrom.
In one way of carrying out this invention in reference to a furnace for the
production of calcium carbide a lower crucible shaped electrode is moved in a
circular line in relation to an upper fixed tube shaped electrode. The crucible
shaped electrode is removably supported in a vessel on the end of a vertical
shaft supported in a foot-step bearing and passing through an opening in a
horizontal plate or partition, the opening being closed by a packing ring. The
footstep bearing is insulated and arranged eccentrically on a bearing plate on
the end of another lower shaft so that when the latter is rotated the upper
shaft and the crucible electrode are moved in a circle under the tubular elec-
trode. The upper shaft is rotably seated in the footstep bearing but non-rotably
connected with the current conductor which is connected to the shaft at one end
and has a bent arm working to and fro in guides when the lower shaft rotates.
In another form of melting apparatus constructed according to this invention
the lower crucible shaped electrode is fixed and the upper tube shaped electrode

page_text: moves in a circular line in relation to the other. The apparatus for effecting
the motion in this case is the same as in the other and differs therefrom only
in so far that the driving parts engage from above and consequently are differ-
ently seated. The upper electrode is eccentrically fixed below its operating
shaft and insulated therefrom.
The material to be treated, some mixture of lime and carbon for the produc-
tion of calcium carbide is introduced through the hollow upper electrode,
furnished beneath with an opening through which the material can be shaken
on to the lower electrode, that is to say, in the space between the latter and the
former, and, during the process of working, the upper electrode is pushed to-
wards the lower, or--which in effect results therefrom-the lower electrode
constantly in a horizontal direction, somewhat in a circular line towards the
upper one, at a certain but adjustable rate of speed, fresh material constantly
falling through the opening in the upper electrode. The material is thus in-
troduced between the electrodes uninterruptedly in an uniformly thick layer
corresponding in height with the distance between the electrodes and is exposed
during a certain period of time which is dependent upon the quickness of the
relative movement of these electrodes, to the action of current which, in these
circumstances, is almost constant. Thus without injurious preliminary heating
and protected against any educts of the melting process in the form of gas
having objectionable effects, the whole of the material introduced in this way
is at once exposed to the action of the current in such a manner that the voltaic
are cannot be deflected or be short circuited, and moreover, all parts of the
material are subjected to action which is absolutely the same strength through-
out. The cross section of the voltaic are may be rather large correspondingly
to the diameter of the upper electrode, the effective resistance being thus
diminished.
It comes also into consideration that many compounds especially calcium
carbide and other carbides are formed at a lower temperature than that of the
arc lamp whence arises a further advantage of the present apparatus in the
following respect; during the relative movement of the one electrode in relation
to the other, the material introduced through the upper electrode falls on to
the superheated melting material (for example melting carbide material) and
so is partially converted into carbide by the mere effect of the heat of the latter,
without any direct action of the voltaic arc. Hence there is a considerable
economy as regards current. Beyond this, by suitable raising or lowering of
the one or the other electrode this new process allows of a continuous work-
ing with the cutting off or drawing off of the melted product, as also of the pro-
duction of blocks.
Instead of only moving the one electrode in relation to the other, it is of
course possible to move both at the same time towards one another in one of
the ways indicated.
Dated this 18th day of August 1899
Improvements in Apparatus for Electrochemical and Electrothermic
Melting Operations, especially for the Production of Calcium
Carbide.
I, EMIL GRAUER, Director of Factory, and Chemist, of Lauffen on the Neckar,
in the Empire of Germany, do hereby declare the nature of this invention and

page_text: 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 an apparatus for carrying out electro-chemical and
electrothermic melting operations, especially for the production of carbide of
calcium.
Apparatus is already known in which the material to be worked is fed
through hollow electrodes, as also apparatus with which the material is placed
in and out of the range of the electric current by means of movable electrodes.
This invention consists in the combination of these two known kinds of
apparatus and further in the arrangement whereby the movable electrodes are
displaced in accordance with the movement of a crank pin. Moreover, the
movable electrode or electrodes may have a motion around its or their own axis
in addition to the movement imparted by the crank.
The essential feature of the present invention accordingly consists in the
following: The material to be worked for example, a mixture of lime and
carbon is introduced through the hollow upper electrode on to the lower elec-
trode that is to say, into the space between the two opposite electrodes, and
during the process of working, the upper electrode is displaced in relation to
the lower electrode, or, what amounts effectively to the same thing, the lower
electrode is constantly displaced in a horizontal direction in relation to the
upper electrode, in accordance with the movement of a crank pin, at a certain
speed which, however, can be regulated, fresh material falling in connection
herewith through the upper electrode. Further, each single point of the upper
or, it may be, of the lower electrode, describes a certain circle through the
radius of the crank. The radius of the crank is determined by the radius of
the upper electrode. By this movement the material is thus spread outwards
in a constantly changing direction, and only within the zone of the voltaic arc
in a uniformly thick layer corresponding to the distance between the electrodes
and is exposed during a certain period, the duration of which is dependent upon
the rapidity of the relative movements of the electrodes, to the action of a cur-
rent which in these circumstances, is approximately constant.
By this method of working an important advantage is obtained; on the one
hand, the material to be treated is not exposed longer than is necessary to the
temperature of the voltaic are and, on the other hand, only as much material is
worked by the electric current, or in other words by the melting temperature
thereby produced, which prevents any decomposition of the carbide already
formed, as often occurs in other processes, and thus a considerable saving is
effected. The process may be employed in interrupted as well as in continuous
working, as in the first case, by the raising or lowering of the electrodes, cakes
are formed in the manner known or in the second case, the smelting material
is run off or cut off. In Figs. 1 to 8, two forms of the invention are illustrated.
Figs. 1, 2 and 3, are respectively a vertical longitudinal section and two hori-
zontal transverse sections of a furnace arrangement constructed according to
this invention, for the production of carbide of calcium. Figs. 4, 5 and 6 are
horizontal sections showing the movement of the lower electrode in relation to
the upper. Figs. 7 and 8 are longitudinal and transverse sections of another
form of the furnace. The lower electrode which has the form of a crucible,
is displaced horizontally in relation to the upper hollow fixed electrode accord-
ing to the rotary motion of a pin which rotates in a crank-shaft bearing. The
electrode b, which in the case of continuous working may be furnished with an
opening (Fig. 1) for running off or cutting off the smelted material, is re-
movably placed in a receptacle c arranged on the shaft i which for the purpose
of shutting out the air, carries a washer d that lies on the fixed plate e, the
lower end of the shaft resting loosely in a bearing f.
The bearing is insulated and arranged eccentrically on a supporting plate of

page_text: the shaft g, so that when the shaft is rotated the electrode is carried round
in a circle below the electrode a.
Here two arrangements are possible. In the first arrangement the shaft i
which rotates in the bearing f is firmly connected with the current-conductor k,
which on the one hand takes hold of the shaft through the medium of a
shackle embracing the shaft, and on the other hand, reciprocates with its
arm m in a guide 7, when the shaft is rotated. By this arrangement, the
material falling out of the hollow upper electrode is drawn centrifugally into the
smelting area in a constantly changing direction. The constantly changing
direction of the material is secured by the dish being moved in a circle below
the lower opening of the hollow electrode, without rotating on its own axis.
In the modified arrangement Figs. 7 and 8, the shackle is placed loosely on
the shaft, spanning it in an elastic or spring-like manner and in this way
conducts the current to it in the manner of a friction-ring. The shaft is thus
rotatively connected with the current-conductor. In this case the electrode a
beyond the crank movement around the shaft g, may have a further rotary
motion around its own axis. In the form of the shackle as in Figs. 7 and 8,
the lower crucible shape electrode is at the same time fixed by way of example,
whilst the upper hollow electrode a is moved in a circle in relation to the
former. The apparatus for effecting the movement is the same in this case,
only differing in that the actuating mechanism operates from above the smelt-
ing apparatus.
The shaft in this case embraces the electrode a through the medium of a
double fork o and thereby, at the same time enables the electrode to be con-
nected in a simple manner with the supply hopper p.
The opening 7 can if necessary be covered with a disc surrounding the elec-
trode and furnished with a central opening, and in the same manner as the
disc d closes the opening in the plate c (Fig. 1).
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is-
1. Apparatus for carrying out electro-chemical and electrothermic melting
operations, especially for the production of carbide of calcium, the distinguishing
feature of which is the combination of the hollow upper electrode a, formed in
the known manner, as a guide or feeder for the material to be worked, with a
lower electrode 6 in the nature of a crucible or disc, the electrodes being arranged
in different planes, and so that the one electrode is displaced in a horizontal
direction in relation to the other (or both electrodes in relation to one another)
while the work is proceeding, according to the rotary motion of a pin. which
rotates in a crank-shaft bearing, in such a manner that the material conveyed
through the upper hollow electrode is forced to enter the zone of the voltaic
arc uniformly, but only so far and in such quantity as can be worked by the
voltaic are or in other words the current intensity prevailing.
2. The improved apparatus for electro-chemical and electrothermic melting
operations substantially as described with reference to the drawings.
Dated this 19th day of April 1900.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.