Process of Manufacture of a Carbide which, by its Decomposition by Water, Produces Acetylene Gas.
Year: 1896

page_text: Belgium.
Date of Application (in United Kingdom), 5th Dec., 1896
Complete Specification Left, 6th Sept., 1897-Accepted, 4th Dec., 1897
PROVISIONAL SPECIFICATION.
A Process of Manufacture of a Carbide which, by its Decomposition by
Water, Produces Acetylene Gas.
I, ALBIN KIESEWALTER, of Limburg on Lahn, Germany, Engineer, do hereby
declare the nature of this invention to be as follows;-
Carbide of calcium is obtained, as is known, by means of an electric current; the
present patent application, however, relates to a process by which carbide can be
obtained in furnaces or ovens capable of giving temperatures from 1300° Cent.
to 1500° Cent.
In order to increase the degree of fusibility of the lime which enters into the
manufacture of the carbide, it is mixed with materials capable on the one hand of
giving off their oxygen when brought to incandescence and on the other hand of
making the lime very fusible at that temperature, for instance, baryta, etc., or salts
which possess only the property of increasing the fusibility of the lime, such as
potash, etc., may be used. After having pulverised the lime, freed of its carbonic
acid by roasting, pulverised coal, coke, charcoal or the like is added, and it is to be
remarked on this head that the lower the temperature of the furnace used, the larger
should be the quantity of pulverised coal or the like to be added.
When the mixture of these materials is sufficiently intimate, baryta, magnesia, etc.,
or potash, soda, etc., are added. Iron ore may also be added in order to increase the
fusibility.
This mixture, which is then treated in a furnace the temperature of which rises
to about 1500° Cent., has the following composition.

page_text: Dolomite can also be substituted for the pure lime and the different materials used
may be combined in any suitable proportions.
The chief point is that the mixture should fuse at the temperature available; the
alkaline earthy metals then part with their oxygen which combines with part of the
carbon added to the mixture so as give off carbonic acid at first, then afterwards
carbonic oxide when the liberation of oxygen is no longer sufficient. When the
escape of carbonic oxide from the retort ceases and when the mixture has the
appearance of a glowing white mass the operation is finished. The whole quantity
of the carbon is combined with the other substances in the state of carbide. The
time occupied by the reaction is about five or six hours.
The new body thus obtained cannot properly speaking be called carbide of calcium,
because its manufacture is not confined exclusively to the use of lime by reason of
the low power of fusibility of the latter; excess of lime in the mixture would render
the fusion of the latter extremely difficult and it would then be necessary to have
recourse to temperatures higher than could be attained in retort furnaces; the
furnaces could not resist these temperatures and besides the process of fusion would
be slow which would materially increase the cost of manufacture.
As the refractory material of which the retorts are made would be attacked by the
substances in fusion and would be finally carried away in the fused mass, it is
necessary that the parts of the retorts in contact with the fused mixture should be
lined with plates of carbon composed according to the well-known method, of coal
du-t, tar and alumina.
These linings wear away little by little and must be replaced as required.
Iron retorts could also be employed but their application would be opposed to the
rapidity of the manufacture and the process would require a considerably longer
time which would increase very largely the cost of production.
The manufacture of the carbide is carried out as follows;-
The materials above specified having been properly pulverised and dried are
introduced into retorts lined with plates of carbon and the retorts are then
hermetically closed.
The vertical tubes of the retorts serve for the escape of carbonic acid and carbonic
oxide which are given off. The progress of the process within the retort may be
observed through an orifice hermetically closed by a pane of glass or the like;
samples of the gas are taken from time to time to ascertain the proportion of carbonic
oxide.
When the escape of carbonic oxide ceases, it can be seen through the orifice
provided for the purpose that the mass within the retort is in a state of fusion and
presents an incandescent lustre..
The carbide is now formed and the retort may be opened. The soft material is
withdrawn by means of a suitable instrument and poured into iron boxes kept in
readiness; in these boxes which close hermetically, the material then cools free from
contact with air. After cooling, it is taken out of the boxes, pulverised and put
into packets and is then ready for sending out and for use.
Dated this 4th day of December, 1896.
SLOAN & LLOYD BARNES
Castle Chainbers, 26 Castle Street, Liverpool.
Agents for the Applicant.

page_text: A Process of Manufacture of a Carbide which, by its Decomposition by
Water, Produces Acetylene Gas.
I. ALBIN KIESEWALTER of Hospital Strasse 6, Limburg a. d Lahn Germany
Chemist and 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 :-
Carbide such as that hitherto produced by means of the electric current in the form
of calcium carbide, can also be produced in retorts or muffled furnaces or in such
furnaces in which the material to be treated is hermetically enclosed both against
the fire gases and also against the outer air, provided that in such furnaces a temper-
ature of from 1300 degrees C. up to 1500 degrees C. is obtainable. The furnaces to
be made use of for this purpose must therefore in order to obtain these temperatures
be specially constructed for this purpose. In the preparation of this carbide in the
aforesaid furnaces it is requisite to remove from the lime the greater part of its
oxygen and to render the same so easily fluxing that it will melt at the above
indicated temperatures in order that it may thus combine with the carbon present.
By the removal of oxygen the lime is rendered already considerably more readily
fluxible. Pure metallic calcium melts at even a low red heat. In order however to
render the lime still more easily fluxible whereby the time required for the operation
is considerably reduced a flux is added to the same such as hydrate of potash,
hydrate of soda, or the like. There can also be made use of as flux salts which act
upon lime as a flux such as common salt and the like but the application of such
salts is preferably avoided as far as possible because through the escaping acid
vapours the iron portions of the furnace are liable to be attacked. Moreover, the earthy
alkalies such as baryta, magnesia and so forth act as fluxes and the same also combine
with carbon to form barium or magnesium carbide and so forth. In order to remove
the oxygen from the lime or the lime mixture, metals are made use of which will
combine with oxygen and volatilise as oxides at a red heat such as zinc, antimony,
and so forth. These granulated metals added to the mixture absorb the oxygen
thereof at a red heat and become volatilized as metallic oxides and are collected as
such in the front of the apparatus or in special condensers so that only a trifling
remainder of them is lost. The recovered metallic oxides can then be reduced in
suitable apparatuses and thus again converted in metal fit for being used again. For
the mixture burnt lime in the form of powder is preferably made use of, after which
is added the granulated metal and then tar or tar oil in order to render the same
plastic. The mixture is then kneaded together by means of a suitable apparatus
such as a pugmill and then formed into blocks. The blocks then formed cohere like
cement and become hard and dry and when in this condition are ready to be treated
in the furnace. A suitable mixture for the preparation of carbide is as follows:-
Lime
45 Parts.

page_text: The combustion of the separate mixtures is determined by the nature of the
materials, and also by the duration of the operation. The above mixtures require
for their complete conversion a period of 6 to 8 hours according as the heat
approximates to 1300 degrees C., or to 1,500 degrees C. Iron ore may also be added
as a flux and de-oxidising material, and ferro-carbonate (FeCO³) is especially
suitable for this purpose. The removal of the oxygen from the lime is in this case
effected by the union of the same with the iron whilst it is in the state of excitation
at the high temperature, whilst on the other hand the carbon unites with the
combined oxygen of the iron to form carbonic oxide or carbonic acid. This alter-
nating action of the iron repeats itself until all the oxygen of the lime is consumed.
The conversion of the mixture first set forth above after conversion of the Hydrates
into Carbonates by absorbtion of CO from the fire gases, at the high temperature
tated is effected according to the following equation:-
Contrary to the assertions in text books hitherto published I have discovered that
calcium carbide contains an atom of oxygen, and that its correct formula is CaOC,.
The carbides CaOC, + KC, are formed, whilst oxide of zinc and carbonic acid escape
and combine to form zinc carbonate which may be collected in a condensing chamber,
whilst CHI, and carbonic acid are liberated and the gas may be made use of for
heating purposes. If water be added to the carbides produced, namely CaOC₂ + K₂ C
the carbides will be decomposed in the well known manner and there are produced
calcium carbonate, carbonate of potash, carbonic acid and acetylene gas. The
carbonic acid which is unable to enter into another combination occurs in the gaseous
condition in the acetylene gas together with any carbonate oxide which may be
formed. If the mixture of the materials has not been entirely thorough it may also
happen in the production of the carbide that together with the above named gases
free hydrogen may also be present in the acetylene gas. The above named mixture
of gases inay be regarded as impurities in the acetylene but the same occur also
in the acetylene gas from carbide which lins been produced by the electric
current.
In order to obtain from the furnace in which the carbide is produced as great an
effect as possible, the inner walls of the retorts or of the receptacles which serve to
hold the materials as far as they can in contact with the materials to be smelted
are lined with carbon so that the acid gases cannot by diffusion render a portion of
the carbon mixture unserviceable for the production of carbide by burning up its
contents of carbon, and on the other hand the clay material which form the retorts
and the like cannot be attacked by the molten mass.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The production and application of carbide by melting together a mixture of
lime and carbon with the addition of salts as fluxes for the purpose of increasing the
fluxibility of the mixture with the use of metals or compounds of metals as reducing
agents.
2. The application of metals for the production of carbide, which are volatilised
as oxides at the high temperature in combination with oxygen, as reducing agent for
the mixture indicated in Claim 1.
3. The application of metallic compounds for the production of carbide, which by
reason of their action when exposed to heat predispose the oxygen in the mixture
set forth in Claim 1 to enter into new volatile combinations.
4. The process of melting together the materials set forth in Claims 1, 2 and 3
for the production of carbide in furnaces in which the material to be smelted is
protected on the one hand against fire gases and on the other against the outer

page_text: air and hermetically closed therefrom, and in which the smelting space for the smelting
together of the carbide mixture as far as the same comes'in contact with the molten
material is protected by means of plates of carbon against the action of the said
material.
Dated this 4th day of Cand
1005
W. P. THOMPSON & Co.,
Patent Agents for the Applicant, 322, High Holborn, London, W.C.