An Improved Process and Apparatus for Producing Caloium Carbide.
Year: 1897

page_text: Date of Application, 30th Nov., 1897-Accepted, 26th Mar., 1898
COMPLETE SPECIFICATION.
An Improved Process and Apparatus for Producing Caloium
Carbide.
I, HERMAN LEWIS HARTENSTEIN, of Bellaire, in the County of Belmont, State of
Ohio, and United States of America, Chemical 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 :-
This invention relates to the carburetting of lime stone, and its object is to
provide a process and apparatus by means of which the carburetting of lime stone
may be carried out on a commercial basis, i.e., with such economy of working and
upon such a scale as to make the same commercially practicable.
My process consists, essentially, in the treatment of crude lime stone by a series
of successive steps, whereby certain impurities of the lime stone are driven off and
the product is then, before parting with its heat, mixed with comminuted or pulver-
ized coke in the presence of a gas or other hydrocarbon fuel between the poles of
an olectrical circuit, the result being the combination of the carbon of the coke
with the calcium of the line stone, and thereby the carburetting of the calcium of
the lime stono.
The chemical reactions by which the carbon of the gas euters into combination
with the limo vary according to the chemical composition of the gna used. Ordinary
illuminating gas is suitable. As there is present an excess of carbon in the form
of coke the oxygen liberated by the decomposition of the lime in the electric
furnace unites with the carbon and hydrogen producing carbon monoxide and some
carbonic acid gas, and also, at the high temperature employed some acetylene.
The calcium freed from its oxygen combines with the excess of carbon and thereby
the calcinm is carburetted.
The apparatus consists in the preferred form of a furnace, the upper portion of
which has a chamber in which the crude lime stone, is calcined preferably by
means of a combustible gas, but the lime stone may be mechanically mixed with a
sufficient quantity of coke to calcine the same and provision inade for supplying air
under pressure to facilitate combustion. This calciuing chamber opens at its lower
end into a second or smelting chamber into which the calcined lime stone feeds
down by gravity. Arranged in the walls of this second chamber are electrodes
forming elements of an electrical circuit. Into this calcined lime stone, while
contained within the second chamber, is forced a suitable proportion of pulverized
coke, preferably by the aid of a combustible gas, the gas serving as the vehicle to
carry the particles of coke and its pressure furnishing the required force to scoure
their incorporation with the mass of burned lime stone. The particles of pulverized
coke being thus intimately mixed with the limo stone serve as conductors through
which the electrical current passes, the particles of lime noting to obstruct or resist
the passage of the current, thus generating and maintaining an intense heat and
rendering tho masa incandescent. The gas serving as the vehicle for the injection
of the pulverised coke is also consumed, adding to the heat and furnishing a
constant supply of the combustible ingredients.
From the foregoing brief description it will be seen that my process is charac-
terized by the fact that the operation upon the lime stone is continuous and that it
is at no time allowed to become cool during the treatment. A further distinguish-

page_text: ing characteristic is the combined effect of the electrical current and of the solid
and gaseous fuel as heating agents upon such lime stone, whereby the same is
highly impregnated with carbon and at such cost and with such rapidity of
operation as to make the same commercially practicable.
The invention, so far as the apparatus is concerned, relates to the novel construc-
tion and combination of its several parts as hereinafter described.
In the accompanying drawings, showing the preferred form of apparatus,-
Figure 1 is a section through the furnace and through a portion of the feeding
apparatus.
Figure 2 is a section partly in elevation at right angles to the view shown in
Figure 1 and taken through the smelting chamber of the furnace which is made
movable, and in duplicate.
Figure 3 is a sectional plan view on the line 3-3 of Figure 2.
Figure 4 is a vertical sectional view through the smelting chamber of the furnace;
and
Figure 5 is a sectional plan on the line 5-5 of Figure 1.
In carrying out my process with the apparatus shown in the accompanying
drawings, I fill the chamber 6 with broken lime stone, intermingled with such
quantity of coke or other solid fuel as will be sufficient to highly heat or calcine
such lime stone. The conformation of this chamber may be as usual and at its
base it is provided with the tuyeres 7 for introducing an air blast. The walls of
this upper chamber may be conveniently supported upon the columus 8, between
which is arranged the track rails 9. Upon these track rails the base, section or
smelting chamber 10 of the furnace is adapted to be moved, being provided with
the wheels 11 to facilitate such movement. In order to expedite repairs or renewals
to the base section of the furnace, which is subjected of course to the highest
degree of heat, I prefer to form duplicate sections, as shown in Figures 2 and 3,
each mounted upon wheels adapted to the track rails and connected at the top of
the plate 12, which serves as a cut off for the material in the chamber 6 when
moving one of the base sections out of line and the other into line with relation
to such upper chamber. The interior walls of the base section are formed by the
linings 13 and the electrodes 14. The latter constitute the poles of an electrical
aircuit, elements of which are indicated by the broken wires 15. It will be
understood that these wires lead to a suitable source of electrical current. The
top of the chamber 6 may be provided with the adjustable damper 16, and near
its top the wall is pierced by the discharge pipe 17 by way of which the gases
liberated by the burning of the lime stone pass off. The external walls and lining
sections of the lower portion of the furnace are pierced by feed apertures forned
of cylinders, each of which is preferably subdivided to form a serios of longitudinal
apertures 18. The arrangement of these cylinders is indicated in Figures 4 and 5,
being shown as piercing the walls at different elovations and arranged in four
horizontal series of four numbers caoh. Each series is in communication through
branch pipes with a supply pipe leading to a trunk 19.
By reference to Figure 5, one of these feed pipes, marked 20, with branches 21,
22, 23, 24 is shown, while the mouths of the remaining feed pipes are indicated in
the boot 25 of the trunk 19. The upper end of the trunk 19 communicates with a
hopper 26 within which a sorew 27 is mounted ou a rotating hollow shaft or
pipe 28, the latter serving to introduce a gas into the trunk 19. The hollow. shaft
or pipe 28 is provided with gears, as 29, 30, to cause its rotation. The bottom
wall 31 of the lower portion 10 of the furnace may be supported on a traveller 32
adapted to a rail 33 located between the rails 9, and such bottom wall may therefore
conveniently be removed at any time to afford access to the base of the smelting
ohamber.
'The complete operation involving the use of my process and the above described
apparatus for carrying the same into effect is as follows: Lime stone,
crushed or broken into pieces of suitable size for treatment, and a suitable
proportion of coke or other solid fuel, are charged into the chamber 6

page_text: the movable base section being preferably in such position as that the table 12
shall close the base of said chamber. The lime stone is calcined in this chamber,
and then the base section of the furnace is moved so as to bring one of the
smelting chambers into communication with the chamber 6, wheroupon the burned
lime in a highly heated condition will feed down into the base chamber by
gravity. The material is thus brought between the electrodes. The carbon
supplying material is then introduced, and preferably in the form of finely pulverized
coke, the same being fed down through the hopper and picked up by the gas
flowing through the pipe 28 under high pressure. This gas, therefore, serves as a
vehicle to carry and force the pulverized coke through the apertures of the feed
pipes and thoroughly intermingle the same with the lime stone. The electrical
current being turned on will find in the molecules of pulverized coke a more or less
perfect conductor, depending upon the particular arrangement of said molecules
with reference to the mass under treatment. The limo stone having low conductivity
offers resistance to the passage of the electrical current and there is thereby
produced an almost infinite number of arcs generating heat and rendering the mass
highly incandescent. The commingled coke and its gaseous vehicle also furnish
heat elements, and the result is the generation of an intense heat which rapidly and
economically effects the reduction of the lime stone, highly carburetted, into a molten
mass, which may be withdrawn through the tap hole 84 at the base of the
chamber.
It will be observed that my process and apparatus secure not only a high
efficiency but also great economy because of the fact that all of the heat produced
is utilized. The lime stone feeding down into the lower chamber by gravity
reaches the base of the chamber in a highly heated condition where it is subjected
to the electrical current, thus conserving heat, while on the other hand the heat
produced in the smelting operation, due to the combined action of the electrical
current and the combustion of the solid and gaseous fuel, is not wasted but, on the
contrary, ascending through the mass of crude lime stone assists in the raising of
its temperature, and therefore in conserving heat energy.
Another highly important foature of my invontion consists, in the continuous,
regular and effective supply of the combustible agent to and incorporating it with
the mass of lime in the smelting chamber.
Difficulties have been encountered in these operations where it has been
attempted to mechanically mix lime with pulverized coke and to convert the
calciuin of the lime into carbide of calcium, bocause of the difficulty of securing a
regular and oven feed of the lime between the poles of the electrical current. The
lime being of very low conductivity offers such resistance to the passage of the
electrical current as to produce a mass resembling slag, which can be removed ouly
with great difficulty, thus rendering the operation very slow and sometimes causing a
suspension or complete interruption antil the furnace can be cleaned. With iny
improved process and apparatus a continuous and therefore profitable working
may be secured.
The particular construction of my apparatus renders comparatively easy the
repair or renewal of its parts and renders the original charging of the furnace ensy
of accomplishment.
While I have described my process as comprehending in the best method of working
the calcining of the lime stone and its smelting by the aid of the electrical current in
conjunction with the combustion of the solid and gaseous fuels as a continuous
operation, still it is evident that if the lime stone wore treated in a separate
apparatus and charged into the smelting chamber, there impregnated with the
carbonaceous and gaseous materials, and subjected to the electrical current, the
essential features of my process would be employed although at greater exponse,
because of the waste heat due to the fact that the lime stone is permitted to cool
after calcination, and to the further waste of electrical energy due to the necessity
of regaining such temperature. This might to some extent be compensated for
by separately heating the lime before charging it into the smelting furnace.,

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. The herein described process of carburetting calcium which consists in calcining
limestone and then forcing into the calcined mass while in a heated condition a
carbonaceous material by the aid of a combustible gas under prossure and
subjecting the mass to the action of an electrical current, substantially as
desoribed.
2. The herein described process of carburetting calcium which consists in mixing,
raw lime stone with a solid fuel and firing the same whereby to drive off its carbon
dioxide, then forcing into the calcined stone a pulverized carbonaceous material and
simultaneously treating the mass with an electrical current, substantially as and for
the purpose described."
3. The herein described process of carburetting calcium which consists in mixing
the lime stone with a solid fuel, firing the mass to drive off its carbon dioxide, then
forcing into the calcined stone while heated a carbonaceous material and
simultaneously subjecting the mass to the action of an electrical current, substan-
tially as and for the purpose described.
4. The herein described continuous process of carburetting calcium, which
consists in mixing raw lime stone with a solid fuel and firing the mass in the
presence of an air blast, then passing the calcined stone in a heated condition
between two electric poles and simultaneously forcing into the calcined stone a
carbonaceous material by the aid of a combustible gas under pressure and
subjecting the mass to the action of an electrical current, substantially as
described.
5. Tho horoin described apparatus, comprising a furnace having a calcining
chamber and a smelting chamber, the latter having separated electrodes arranged
in its walls, feed pipes perforating said walls and arranged in horizontal series, a
plurality of branch pipes connecting with said feed pipes and a trunk connecting
with the several branches and means for forcing a pulverized carbonaceous material
through said trunk, the branches thereof and the several feed pipes into the smelting
chamber, substantially as described.
6. In a smelting furnace, the combination with a smolting chamber having
separated electrodes arranged in its inner walls, pipes or passages piercing said
walls, branch pipes communicating with the outer onds of said feed pipes or
passages, a trunk communicating with the several branches, and means for
dolivering a carbonaceous material into said trunk and a means for delivering a
gascons vehicle under pressure into the trunk whereby to carry the pulvorized
carbonaceous material into the furnace, substantially as described.
7. In an electrical smelting furnace the combination with a calcining chamber
supported in an elevated position and having an opon bottom, of a plurality of
smelting chambers each open at its upper end and capable of being moved into and
out of operative relation to the calcining chambor and each having electrodes in
its walls, substantially as described.
8. In an electric smelting furnace the combination with a calcining chamber
supported in an elevated position, of a track arranged beneath said olevated
portion and between its supports and a baec portion movably mounted on said
track, electrodes mounted in the walls of the movable portion and pipes or
pasanges opening into the chamber thereof adjacent to the electrodes, substantially
as described.
HASELTINE, LAKE & Co.,
45, Sonthampton Buildings, London, W.C.,
Agents for the Applicant.