Apparatus and Process for Condensing the Metallic Vapours Produced in Zinc Furnaces, and Furnace Applicable in Combination with the said Condensing Apparatus.
Year: 1889

page_text: Date of Application, 27th Sept., 1889
Complete Specification Left, 27th June, 1890-Accepted, 2nd Aug., 1890
FRUVIDIUNAL TULERUATION.
Apparatus and Process for Condensing the Metallic Vapours Produced
in Zinc Furnaces, and Furnace Applicable in Combination with
the said Condensing Apparatus.
We, EDUARD GRÜTZNER, "Grubenpräsendant," at the Romagna-Mine near Loslau,
and OSKAR KOEHLER, Mining Director, of Czernitz, both in. Upper Silesia, Germany,
do hereby declare the nature of this invention to be as follows:
Our condensing apparatus is applicable to all kinds of zinc distilling furnaces and
comprises:
A pair of lead-coated tanks placed close together, one after the other, the bottom of
the second tank slanting down towards the further or discharge end, where it has a
collecting trough. Each tank has an inlet and an outlet for cooling water which
circulates constantly.
The first tank contains a condensing vessel made of sheet-metal, and completely
immersed in the cooling water, being preferably suspended from a pair of beams.
Into the second tank dips a cooler, which consists mainly of a rectangular frame
open at the bottom, but closed at the top and at the sides, and provided with vertical
partitions which are gradually placed nearer together towards the farther end of the
cooler and form a kind of labyrinth or zig-zag course for the gases and vapours that
pass between the said partitions. A large syphon tube connects the top of the con-
denser with the top of the cooler.
The further (or discharge) end of the second tank contains a hermetically sealed
safety box situated above the level of the cooling water. This box may be filled with
water through a funnel pipe provided with a stop-cock and serves to intercept com-
munication between the cooler and the atmosphero, being connected on one side with
the gas space of the cooler by a thin syphon pipe reaching nearly to the bottom of
the safety box, and on the other side with the atmosphere or with a furnace by a small
discharge pipe.
The top of the condenser is connected with the distilling apparatus or retorts,
by pipes that are partly detachable and provided with hermetically closing joints.
Before establishing connection between the retorts and the condensing apparatus,
the safety box and the condenser must be filled with water. The connection having
been made and rendered air tight, and the development of gases and vapours in the
retorts having commenced, the water contained in the condenser is pumped into the
second tank by means of a hand pump and a pipe extending nearly to the bottom
of the condenser, until the water level in the condenser is only about 100 millimetres
above the lower end of the said pipe. By this operation a vacuum is produced in the
whole apparatus from the retorts to the safety box, in consequence of which the
volume of vapour and gas entering the apparatus expands and the metallic vapours
are condensed.
Metallic oxides, however, which are carried by the gases from the condenser
into the cooler, fall into the water of the cooler during their zig-zag course (from
the large syphon pipe to the safety box) and settle at the bottom of the second
tank.
If now the water in the safety box is discharged into the tank through a thin pipe
attached to the bottom of the safety box, and then the said pipe again closed by a
stop-cock, the gases will pass from the cooler to the safety box and thence through
a pipe conduit to the furnace of the distilling apparatus or into the chimney of the
same. In either case a suction is produced which sets the condensing apparatus in
full operation.
The distilling furnace, which we prefer to use in combination with our improved
condensing apparatus, is constructed as follows:→
:
It comprises .four or six vertical shafts of elliptical cross section, the said shafts

page_text: being grouped radially around the axis of the furnace and joined together in the
centre, so as to form a single space having four or six radial branches surrounded by
a common wall of fire proof material. This wall, together with the pillar in the
centre of the furnace, is supported by a fire proof brick arch, which separates the
discharging space, or lower part, from the upper part of the furnace.
Each of the vertical shafts contains a vertical retort, likewise of elliptical cross
section, which extends downward through an elliptical opening of the arch and rests
on an iron shoe or socket piece secured to a short pillar of brickwork Each of
these shoes has at the top a hermetically closing socket for the retort, and at the
bottom an oblique outlet towards the axis of the furnace, which outlet is closed
hermetically by a cover. At the top each retort extends slightly above the shaft
and has a hermetically closing lid provided with an opening for introducing the
zine ore, which opening is also provided with a hermetically closing lid. A large
pipe, that extends through the main cover (or is attached to the same) serves to
conduct the volatile products of distillation to the condensing apparatus, and a thin
test pipe, that extends through the lid and is closed at the top with a plug, serves to
examine the condition of the retort or the stage of the process, when required. The
wall, in which the four or six shafts are formed, contains a narrow outer flute which
surrounds the shafts at a short distance from the same and is almost concentric to the
outer parts of the retorts. The furnace thus has two flues, namely the inner flue or
annular space between the retorts and the walls of the shafts, and the outer flue that
is separated from the inner flue by a thin wall or lining of brickwork. The heating
gases are conducted by a horizontal passage to the inner flue, pass around the retorts
and escape through a large number of radial perforations into the outer flue that
communicates by another horizontal passage with the chimney. For charging the
retorts, the shoes and the lower part of each retort, up to the level of the brick arch
are filled with ashes or other suitable bad conductor of heat, after which the retorts
are charged with zinc ores.
Dated this 97th day of September 1880
COMPLETE SPECIFICATION.
Apparatus and Process for Condensing the Metallic Vapours Produced
in Zinc Furnaces, and Furnace Applicable in Combination with
the said Condensing Apparatus.
We, EDWARD GRÜTZNER, Manufacturer, of Loslau, and OSKAR KÖHLER, Manu-
facturer, of Czernowitz, both in Silesia, Germany, do hereby declare the nature of
our invention, and in what manner the same is to be performed to be particularly
described in and by the following statement and with the aid of the accompanying
drawings, of which :-
Fig. 1, is a vertical section and
Fig. 2, a plan of a condensing apparatus embodying our invention; while
Fig. 3, is a vertical section and
Fig. 4, a horizontal section of an improved furnace, or sublimation apparatus.
Our novel apparatus for the condensation of metallic vapours produced in the
manufacture of zinc in sublimation-furnaces of whatsoever system chiefly comprises
two masonry chambers A & B built in the same line with one another and lined with
lead, the latter chamber B having a bottom with a slope of 4: 100 and a collecting
trough P at its lowest part.
Cooling water runs continuously in and out of both chambers.
The chamber A contains the sheet-iron condenser C, which is held down in position
by the iron rods b, 6 (of rectangular section) which are securely anchored in the
masonry, in such a way as to impede the entry of the cooling water.

page_text: The cooler K, which is provided with a labyrinth consisting of compartments which
gradually grow smaller and whose walls gradually approach one another, projects into
the chamber B, its lowest portions reaching about 100 millimetres under the water,
and hanging from iron rods which rest on the walls of the chamber. The surface is
cooled by water.
The condenser C and the cooler K are connected with one another by means of the
tube R, and at the side of the cooler K furthest from C is connected with it by means
of tubes the safety chamber S, by means of which the entry of atmospheric air into
the apparatus may be completely prevented, and this is effected by filling the safety-
chamber S with water through the funnel T.
The condenser C is constructed in such a manner, that it can be connected either
with the upright retorts of the furnaces of our new system (Figs. 3 & 4), or with the
muffles of the furnaces hitherto in use, by the connecting tubes rrrr (of which a
number corresponding to local requirements may be introduced) by means of the sheet-
iron sleeve-tubes hhhh, and this in such a manner that,
1. For connecting with the upright retorts (Figs. 3 & 4), cast iron knee
tubes k.
2. For connecting with the horizontal muffles, after the usual receivers have been
removed, plain cast iron tubes are to be inserted into the above mentioned sleeve-tubes,
and then drawn up and introduced into suitable openings in the lids of the upright
retorts (Figs. 3 and 4) or in the front wall of the muffles and luted with clay.
An unimportant variation in the arrangements which may be dictated by local
circumstances consists in connecting simultaneously two or more retorts or muffles by
means of T tubes instead of the short connecting tubes (Figs. 1 & 2) and the bent
tube (Figs. 3 & 4). In this case, the connections must be made at the proper
place in each branch in such a manner that by attaching a stop-tube, each retort or
mufle may be thrown out of connection, so as to avoid interfering with the working
of the others.
It may be mentioned at this point, that connections between the apparatus and
the retorts must, if the combustion of the zinc vapours is to be avoided, only be
effected, when the safety vessel or chamber S and the condenser (the latter by
means of the tube w reaching nearly to its bottom) have both been previously
filled with water.
After the connection between the retorts or muffles and the condensing apparatus
has been established, as described above, and all points at which leakage might
occur carefully luted up, which is best effected by means of a thin sandy clay,
and after the liberation of vapours and gases has commenced, the water contained
in the condenser is pumped into the vessel or chamber B by means of a hand
pump introduced into the tube w, until the tube w extends only about 100 millimetres
below the surface.
This operation produces a partial vacuum in that part of the apparatus situated
between the retorts or muffles and the safety cap S, and in consequence the vapours
or gases entering (from the retorts) expand and the metallic vapours are condensed
and precipitated.
Metallic oxides (zine dust), which are carried forward mechanically by gases which
traverse the cooler K and the cross tube R, are thrown down as these pass along the
zig-zag course which they have to pursue towards the safety-cap S, and fall through
the water contained in the chamber B on to the bottom of the same.
If now the water be removed by means of the cock n at the bottom of the
safety box S, through the tube n', and the cock n is immediately shut again, a way is
made for the waste gases by means of the tube connection, either towards the
hearth of the furnace or towards its flue-both of which exercise a suction, and the
condensing apparatus is set fully in action.
The stream of gas is so strong as to prevent the entry of atmospheric air at the end
of the tube connections z'.
When at the end. of a certain time (somewhat less than two hours) the material

page_text: in the retorts or muffles has been driven off, the charging of the reforts or
muffles is commenced, the safety cap S being filled with water to prevent the
entry of air.
The charging takes place through specially adapted openings in the covers
of the upright retorts (Figs. 3 & 4) which are provided with small lids d, in
such a manner, as to avoid interrupting the connection between the retorts and the
condenser.
In the case of muffles in the old system of furnaces, the same end may easily
be attained by arranging similar openings with devices for closing them in the working
wall.
After the retorts or muffles have been freshly charged, all leakage points luted up,
and the liberation of metallic vapours has commenced, the safety cap S is again
emptied, as described above, and the condensation of the vapours issuing from the
retorts begins afresh, and they pass as in the case of the previous charge and the other
escaping gases either towards the hearth or towards the Hue.
After the lapse of a few days, a short rest should be made for the purpose of
recovering the metallic products which have collected in the condenser C, the
amount of which is shown at any given moment by the height of the water-an
observation which it is most advisable to make at the time of charging.
For this purpose the safety box S, and the condenser C are filled with water,
the cover is removed from the condenser man-hole M, and the metallic precipitate
which has collected is removed with shovels, for the purpose of subsequently smelting
or refining it.
When the man-hole M has been reclosed by means of the cover, the apparatus is
again set in action in the manner described above.
The zinc oxide which has collected on the sloping bottom of the chamber B under
the cooler K in the form of mud, is raked into the trough P by means of wooden
rakes, when a sufficient time has elapsed, and removed without giving rise to any
interruption of the process.
If owing to any cause it appear advisable to disconnect one or other of the retorts
or muffles, the particular retort or muffle is not recharged. In this case, the safety
cup S and the condenser must be filled with water. The particular sleeve-tube his
loosened at the flange of the connecting tube, and together with the knee k
which projects through the cover of the retort D or the tube which projects through
the working wall of the muffle, removed and replaced by the closed piece belonging to
the tube .
change of the retort or muffle can thus be made without interfering with the
operation of those on either side. The connection with the condenser C is of course
made after it and the safety-cup S have been filled with water.
The small tube p in the partition wall effects the removal of the cooling water from
the chamber A to the chamber B.
As there is usually but little room to spare between the furnaces in zinc works as at
present built, it is one of the advantages of the system here described, that the
condensing apparatus can be built and the operations for which it is designed conducted
outside the furnace room.
it is, however, always advisable to arrange two sets of condensing apparatus in
chambers common to the two on both sides of the furnaces they have to serve.
This novel condensing apparatus possesses the following advantages:
1. From the hygienic point of view:
It prevents the escape of metallic vapours and oxides which may have an injurious
effect on the health of the workmen, such as carbon monoxide.
2. From the point of view of economy:
It decreases the cost of production by diminishing the loss which has hitherto been
unavoidable and has amounted to 20-30%
The full advantage of the condensation-apparatus becomes especially apparent, when
it is combined with the upright retort for zinc distillation shown Figs. 3 & 4 of the

page_text: accompanying drawings: This retort furnace consists of four or six shafts open
towards the centre, each of elliptic section and surrounded by one common wall of
masonry externally braced by iron rails.
The two linings and the column p, the former being built of wedge-shaped-the
latter of ordinary fire-bricks, rest upon the vaulting K which in its turn is also made
of fire-bricks.
For the purpose in view, special bricks of fire-resisting material are built into
the vaulting K; they are made with elliptical holes corresponding to the section
of the retorts R1, R2, R3, &c. in order to permit of the retorts being inserted from
above through them into the collars of the cast-iron shoes S which are supported by
the columns P.
The space below the vaulting K between each of the pillars or columns as also
between them and the outside wall enables the workmen both to carry out, the
luting and to remove the residues from the retorts R.
The dimensions of the retorts as regards height and section depend upon the
amount of ore they are required to hold for metallurgical treatment, and upon local
circumstances.
The retorts are lowered into the vertical compartments from the furnace plat-
form, by means of pulley blocks, and their lower ends are fitted into the collars
of the cast-iron shoes S each of which is previously fitted with an asbestos ring to
render the joint air tight. They are preserved in a vertical position when the wedge-
shaped fire-bricks are stamped in round them with fire-clay mortar at the upper
surface of the furnace, in such a way, that they are rendered incapable of altering
their position in the future.
All leakages are carefully luted with a thin sandy-clay.
After this, the covers D, each of which is provided with three openings
and which are shouldered into the retorts are smeared with clay and placed in
position.
The cast-iron knee-tube one arm of which is flanged into the sleeve-tube h
of the condenser C (Figs. 1, 2) may be drawn out and inserted into the opening g
in the retort cover D, where it is lated as at its connection with the sleeve
tube h.
The short earthenware tube a for observing the progress of the distillation, is also
arranged in the cover D and luted, and a stopper consisting of plastic clay rolled in
linen is to be placed upon it.
When the covers have been laid upon the flanges of the cast-iron shoes S-asbestos
rings being fitted in at the same time, and secured by the screw clamps z, and when
also a small lid & has been fitted loosely into each of the openings o in the large retort-
covers D, the furnace is connected up to the condensing apparatus (Figs. 1 & 2)
and is placed in readiness for the preliminary warming and ultimate operation to
commence.
The temperature of the furnace is gradually raised, either by means of a hearth
arranged at the side, or by laterally intro luced gas firing, until the retorts have reached
al bright red heat, which may be ascertained by removing the small lid d.
The gases of combustion are introduced laterally through two canals y into the furnace,
which in virtue of its construction nowhere presents any waste space, and presents to
them the largest possible retort-surface in the passages. The gases pass through
the lining F by way of the passages or openings i, whose combined sectional area
equals that of the two channels y by which the gases enter; and from there they pass
through and the channel y' to the fireplace of the next furnace, or as the case may
be, to the chimney.
As soon as the retorts R have been raised to a bright red heat, they are charged
from the furnace stage, ashes-a bad conductor of heat-being first introduced
through the opening o in the cover D, (the lid of which (d) has been removed) till it
fills the retorts up to the level of the top of the vaulting, whereupon the ores mixed.
according to sample, and which have been previously unloaded on to the platform, are
charged in, until they fill the retorts nearly up to the lid.

page_text: After this, the small lids d are replaced in the openings o and luted in and the retort
thus closed.
A layer of sandy clay over the retort cover D, which also reaches to and partially
covers the furnace platform or stage, acts as a preventative against subsequent leakage
or injury to the cover D.
As soon as the development of steam begins in the retorts-which is ascertained by
raising or lifting the clay stopper of the small tube x,--the water is removed, first
from the condenser C, and then from the safety-cup S, in the manner already described
above, the working of the apparatus being thus started.
When, after the lapse of 18-24 hours, the contents of the retorts have been
sublimated (which is ascertained by lifting the clay stopper mentioned above) the
charging" is commenced, to which end the safety-cup is filled with water as described
above.
Thereupon the clay luting above and round the smali lid d, is removed, that is to
say, the small lid laid bare, care being taken not to disturb the others. Then the
screw-clampy of the flange S of the cover is lifted off and the residue which falls out
removed in a truck.
Too violent cooling of the retort is avoided by having only one opening, either
above or below uncovered at the same time, so as to avoid the formation of a current
of air.
.
The opening o is employed for the purpose of removing any residues that may remain
hanging round the sides of the retort, the cover being previously attached to the bottom
flange of the shoe S by means of two clamps.
After the two clamps have again been loosened and the cover removed from the
flange, the residue that falls out of the retort is carried away and the cover again
tightly fastened up.
In this way, all entry of air being avoided and any perceptible cooling of the
emptied retort prevented, the charging is recommenced as in the previous instance by
filling up with ashes to the upper level of the vaulting and then with the sampled
mixture of ores from above through the opening or orifice, the cover D again luted
in position, and the layer of clay on top of it is renewed, after which the retort R²
and the remaining retorts are treated in a similar manner.
In this way, the six retorts of a furnace may be charged in about half an hour
without any inconvenience arising to the respiratory organs of the workmen.
By re-emptying the safety-cups (Figs. 1 & 2), the operation is again set going, and
after the lapse of several days, the products may be removed in the manner mentioned
above.
The retorts previously described are made of a plastic fire-clay mixture and receive
a preliminary burning.
For the purpose of attaining long periods of uninterrupted work, it would seem to
be of the highest importance, to make use of bricked retorts. These may easily be
built up from the shoe S as a basis or foundation.
As the zine ores which are generally subjected to metallurgical treatment contain
not only zinc, but also other metallic oxides (oxides of lead, cadmium &c.), the furnace
which is the subject of this description, serves in combination with the condensing
apparatus described at the commencement for reducing this class of ores and the
latter the condensing apparatus-is better and more suited for recovering all the
distillation products than any system hitherto in use.
The new distilling or sublimation furnace offers the following advantages for the
manufacture of zinc in comparison with other methods hitherto in use.
1. A lowering of the cost of labour, as in consequence of its construction, it requires
but little attention, and does not necessitate the employment of specially trained
workmen.
2. A greater output in consequence of the easier charging and emptying of the
retorts in comparison with horizontal muffles, and as a consequence, the avoidance of
loss through the connection with the condensing apparatus.
3. A smaller consumption of fuel in consequence of the more compact.construction.

page_text: 4. A saving of retort and fire resisting materials, since the upright retorts with
walls of equal thickness throughout are not liable to the variations of tension, to
which the muffles hitherto in use with their edges and walls of varying thickness are
exposed, and are consequently less likely to crack; and further because the tenacious
glassy slags formed by the iron contained in the ores cannot accumulate attacking the
walls and taking up space, but must fall regularly (to the bottom) and are easily
removed at the time of charging.
The receivers and vaultings hitherto employed are dispensed with.
5. The inhalation of injurious vapours and oxides by the workmen is prevented, and
the metallic vapours are condensed.
Having thus particularly described the nature of our invention and the means
by which it may be successfully carried out, what we claim is :-
1. Apparatus for condensing the metallic vapours produced in zinc furnaces, com-
prising in its construction a pair of tanks A and B provided with a continuous supply
of cooling water, a condenser placed in the tank A, a cooler K dipping into the
tank B and provided with a series of partitions adapted to form a gradually narrowing
zig-zag course, a tube R connecting the condenser with the cooler K, and a safety
cup or box S adapted to form a water-seal in the outlet from the cooler, substantially
as described.
2. The process for condensing metallic vapours by means of apparatus as described
in claim 1, which consists in connecting the said apparatus with the furnace in the
manner described, then (after the generation of vapours and gases has commenced)
pumping a part of the water, contained in condenser C, into the tank B, thereby
rarefying the air, subsequently emptying the safety box S filled with water and
connecting the discharge pipe 21 of the same with the flue or fireplace of the furnace,
in order to produce a suction, substantially as described.
3. A zinc-furnace comprising (four or six) shafts of elliptic section open towards
the middle and confined within a common exterior wall, cast-iron shoes S, fire-clay
retorts Rarranged in the shafts, covers or lids D and d fitting into the retorts, channels
or passages y acting as conduits for the heating gases, heating ore fire-flues f, external
flucs connected with by means of orifices i, and a chimney flue y', substantially
as described.
Datad this 26th day of June 1800