Process for the Production of Calcium Carbide in Blast Furnaces.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Process for the Production of Calcium Carbide in Blast Furnaces.
I, FRANZ JOSEF BERGMANN, of 5, Mohnestrasse, Neheim on the Ruhr, in the
German Empire, Manufacturer, do hereby declare the nature of this invention to
be as follows:
The economical production of calcium carbide on a large scale has been retarded
by the use of electric furnaces on account of the unavoidable interruption in the
working.
The present process is designed to reduce the price of calcium carbide, by a
continuous working and the suppression of the electric furnace, and so render the
use of acetylene gas more general for illuminating purposes.
To enable the process to be carried out in blast furnaces, it is necessary to
obtain a temperature of about 3000° C. which is required for the reaction while, at
the same time, by a suitable construction of the furnace, to prevent the material
of which the furnace is built, from becoming destroyed by the high temperature.
The former can be attained by means of an oxygen blast, the latter by the use of
a water jacketed furnace.
As the cheap production of oxygen is of the highest importance for economically
producing calcium carbide, it is necessary to combine with the process for obtain-
ing this latter, a process for producing oxygen.
The temperature obtained by the use of an oxygen blast exceeds by far the
intensity required for the reaction. If, for example, coke and oxygen be used,
the temperature rises to
42000
22.0,25
= 7640°.
By using liquid hydro carbons instead of coke, the temperature is raised to as
much
= 11800°.
308000
108.0,25
From this it will be readily seen that for the purposes of my process pure
oxygen is not required, and impure oxygen obtained by any method may be used,
and such oxygen may even be mixed with atmospheric air.
The arrangement for carrying out my improved process comprises a pair of
furnaces for the alternate decomposition and regeneration of manganese peroxide,
and an air blast combined with both furnaces in such a manner as to alternately
supply air to that furnace in which the regeneration takes place.
Between the oxygen generating apparatus and the calcium carbide furnace, a
gasometer is interposed for collecting the oxygen and regulating the blast.
Where coke is to be used, the arrangement for producing calcium carbide com-
prises a middle part for the reception of the reaction mixture, and two columns at
the sides thereof for the coke. The oxygen, or oxygen mixture, is forced by
means of a blast into the lower part of the furnace and passes horizontally through
the coke, from both sides, and comes into contact with the lime and coal, in the
middle part, through suitable openings.
The essential feature of the improved calcium carbide furnace is that its lower
part forms a double-walled smelting hearth for the circulation of water, whilst its
[Price 8d.1

page_text: upper part is built of refractory material, the temperature therein being a com-
paratively low one.
Water-jacketed furnaces have heretofore been used in connection with the pro-
duction of lead and copper with the best results, under temperatures of 1700 to
1800° as required in such industries. To render these furnaces safe for tempera-
tures of from 3000 to 4000° it is sufficient to pass double the volume of water
through the jacket. If the process is to be carried out with hydro-carbons instead
of coke, the usual form of water-jacketed furnace may be employed. The oxygen
and hydro carbon are introduced by the blast into the lower part of the cylindrical
water jacketed furnace in such a manner as to ensure thorough mixing.
Process for the Production of Calcium Carbide in Blast Furnaces.
I, FRANZ JOSEF BERGMANN, of 5, Mohnestrasse, Neheim on the Ruhr, in the
German Empire, Manufacturer, 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, reference being had to the accom-
panying drawings and to the letters and figures marked thereon, that is to say:-
The production of calcium carbide without the aid of electricity is an exceedingly
difficult matter, and owing to the interruptions in the working when using an
electric furnace, the first outlay is too expensive to bring lighting by acetylene
gas into general use.
I overcome this difficulty so far, by working on the principle of the blast fur-
nace, that is to say by a continuous introduction of the requisite material at the
top, and the removal of the molten material from the bottom.
There are, however, still two difficulties in connection therewith, the first of
which is, that the temperature of a blast furnace, even with a hot blast, never
exceeds 1600 to 1700° C. while 3000° are required for melting calcium carbide
(the exact melting point not having yet been determined); and the second is, that
no materials exist which can resist such temperatures, seeing that not only all
metals, but also all minerals,.ordinarily considered as refractory, melt at such
temperatures.
All these difficulties are, however, entirely overcome by the process and means
about to be described, and which process is based, with but slight differences,
upon the ordinary principle adopted in metallurgy.
The following are the means adopted for carrying out the process: A water-
jacketed furnace, such as used in lead and copper works, is kept in continuous
working, since it does not require frequent repair like those constructed of refrac-
tory materials.
These latter are unable to withstand the melting temperature for calcium car-
bide, whereas a water-jacketed furnace provided with water circulation is
absolutely durable.
As the heating of the water by the metallic walls is in proportion to the differ-
ence in temperature, it is only necessary to cause double the quantity of water to
circulate when raising the temperature from 1600 to 3200° C.

page_text: Now, instead of using an electric current, I employ another means of heating,
and this consists in burning coal and lime in the presence of an oxygen blast
(either pure oxygen, or a mixture of air and oxygen). Hence, the new process of
producing calcium carbide is closely connected with the commercial production of
oxygen.
This production may be effected, for instance, in the following manner.
Manganese peroxide is treated by a simple metallurgical process, by heating
it to a red heat so as to cause it to part with one third of its oxygen, or 12.5 %
of its weight. On afterwards exposing the brown manganese oxide (obtained by
decomposing MnO2) to the action of an air current at a temperature below that of
red heat, it oxidises into peroxide. It is obvious that the heating must be so
regulated as to first obtain oxygen and then again form manganese peroxide.
By this means the required oxygen is obtained for use in the production of the
desired high temperature, whether for use in conjunction with coke, liquid hydro-
carbon, or with any other suitable combustible material.
The oxygen is collected in a gasometer, and the blast can therefore be regulated.
The melting of the mixture into carbide is carried out in a water jacketed
furnace, the construction of which depends upon the fuel (coke, or liquid hydro-
carbon) employed.
The general arrangement of the means is shewn in the drawings in Fig. 1,
wherein A is the water-jacketed furnace into which oxygen is introduced in the
form of, say, a blast, by means of a root blower b. This fan draws in oxygen
from the gasometer d which is supplied from two decomposing furnaces B, B¹, one
of which alternately supplies the oxygen while the other regenerates the manganese
peroxide. A blast fan f supplies atmospheric air to the two furnaces alternately.
These two furnaces are shewn in Fig. 2 in elevation and in transverse section,
respectively, Fig. 3 being a horizontal section and a plan thereof, and Fig. 4 a
longitudinal vertical section.
Both furnaces are similarly constructed, and thus only one need be described.
It comprises a muffle C of refractory material, enclosed by brickwork D, and a
fire grate E, the products of combustion from which pass between the muffle and
the brickwork. The whole furnace is so constructed, and the parts connected
together in such a way by stay bars, or the like, as to effectually prevent any
tendency to displacement.
The manganese peroxide is introduced at a single charge and is spread over
the sieve-like perforated shelves W, W, which are covered with an asbestos sheet
(see Fig. 7) to prevent the granular material falling through the perforations.
The muffle is provided with a pipe H having a valve m through which oxygen is
drawn off, and with a two branch pipe K, K, with valve n for atmospheric air.
If the furnace is employed for the production of oxygen, the valve n is closed,
and the valve m is opened, but for the regenerating process, the position of the
valves is reversed.
During the first period of the process, a high temperature is maintained, while
during the second period the temperature is lowered to 400 or 500° C.
It will thus be seen that a continuous generation of oxygen takes place, although
carried out alternately in the one or the other furnace. The oxygen is collected in
a gasometer which also serves for controlling the regular working of the furnace
during the production of the oxygen.
As has already been mentioned, the water-jacketed furnace may be fed either
with coke, or with liquid hydrocarbon.
The arrangement for coke firing is shewn in Fig. 5 in vertical section, and in
Fig. 6 in horizontal section.
It is advisable to form the material (viz.: a mixture of lime, and coal) for charg-
ing the furnace, into briquettes, and then to introduce them into the blast furnace,
wherein they are gradually melted. Whatever may be the nature of the fuel used,
it is essential that combustion be as complete as possible.

page_text: A suitable arrangement for a coke burning water-jacketed furnace is to divide
the furnace into three parts P, P1 and P2, in the first of which the charge is intro-
duced and the melting effected, and in the last two of which the coke is consumed
in the presence of oxygen.
The lower portion of the middle part P is provided with a water-jacket M, and the
remaining portion is constructed of refractory material. The hearth U is con-
structed of a block of graphite and is supported on the foundation brickwork of
the furnace; the two parts P1, P2 rest on gratings g, g, adapted to support the fuel
and allow the ashes to fall through. The ashes may be removed either by momen-
tarily shutting off the blast, or by fusing them with a suitable medium and then
collecting them in the form of slag.
The oxygen passes from the fan through the pipes 0, 0), and nozzles T, T, into
the burning coke in a horizontal direction, it being necessary to adapt the volume
of oxygen to the quantity and the thickness of the lover of coke so as to insure
complete combustion. The heat thus produced circulates through openings V
in the water jacket M, into the interior of the melting furnace.
The charging hoppers N, N1, N2, of the combustion chambers must be kept
closed so as to avoid loss of oxygen. They are shewn in the drawings as being
provided each with a slide t and with a cover, the latter being closed before open-
ing the slides.
The furnace above described for burning coke is advantageously of rectangular
form, and comprises two coke combustion chambers and two rows of nozzles, but,
if desired, only one such chamber may be provided, and, in such case, the calcium
carbide chamber must be made proportionately smaller.
For liquid fuel, the water jacketed furnace is preferably of cylindrical form,
similar to those used in lead and silver works, and is as shewn in vertical section
Fig. 8, and in horizontal section Fig. 9. The water jacket has 4 to 6 sockets into
which enter tubes R₁ forming, at one and the same time, the mixing and the com-
bustion chambers. The oxygen is supplied through nozzles in connection with an
annular pipe O. The hydro-carbon jet is atomized by these nozzles and mixes
intimately with the oxygen, so resulting in perfect combustion, provided the pro-
portions of the liquid fuel and the oxygen be properly regulated. With this mode
of firing, a higher temperature is obtained than with coke.
By using hydro-carbon, a larger volume of atmospheric air and a smaller volume
of oxygen will be sufficient. In both modes of firing, even allowing for a reduc-
tion of temperature in practice, there will always be considerably more heat than
required, and hence, the use of electricity for melting calcium carbides is rendered
unnecessary.
The economy effected by the introduction of this improved process naturally
depends upon the price of the fuel, but the cheapness of the process is due to its
continuous working.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same may be performed, I declare that what I
claim is:
1. In the production of calcium carbide, without the aid of electricity, the
employment of an oxygen blast in combination with a furnace provided with a
water jacket surrounding the smelting zone.
2. A furnace for carrying out the above claimed process, in which solid fuel is
burned, comprising three chambers, the middle one of which is charged with a
mixture of lime and coal, while the two outer ones are charged with the fuel for
combustion, substantially as described.
3. A furnace for carrying out the above claimed process, in which liquid hydro-
carbon is used as fuel, comprising a single chamber and a suitable blast apparatus,
substantially as described.
4. For obtaining the oxygen necessary for carrying out the herein described

page_text: process, decomposing and regenerating manganese peroxide in the manner herein
described.
5. In the manufacture of calcium carbide, the production of oxygen for use
therein by the employment of two furnaces in combination with an air current,
and in which furnaces manganese peroxide is spread over sieve-like perforated
shelves, as and for the purpose described.
6. The use of the process and apparatus, characterized in Claims 4 and 5, for
the production of oxygen for use in the manufacture of calcium carbide.
Dotad this 91ot dove of Wahnuo 1900
ERNEST DE
PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 5A, Market Street, Nottingham,
Agent for the Applicant.