Improvements in Furnaces for Smelting Zinc Ores or other Materials Containing Zinc, and in the Mode of Operating' therewith.
Year: 1885

page_text: Improvements in Furnaces for Smelting Zinc Ores or other
Materials Containing Zinc, and in the Mode of Operating'
therewith.
I, LUDWIG KLEEMAN of Myslowitz, Silesia in the German Empire, Director of
Mines, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved construction of furnaces for smelting zinc
ores or other materials containing zinc and to the mode of operating with the said
furnaces, which I will proceed to describe with reference to the accompanying
drawings.
The furnace consists of a larger or smaller number of reduction chambers a¹
arranged side by side and separated by partition walls, and having at top closed
charging hoppers g while their lower restricted ends a' communicate with air or
beating chambers h provided with doors in the vaults below the floor.
At the front sides of the chambers a¹ are arranged extensions of suitable height
and width containing the condensing apparatus communicating with a' by means
of correspondingly arranged superposed openings d. At the back of the reduction
chambers a' are situated the combustion chambers b, communicating with the
former by passages c, through which consequently the flames pass, thus representing.
a vertical heating surface communicating from top to bottom with the column of
material contained in the reducing chambers.
The combustion chambers are fed with gaseous fuel passing in from the gas
producers through flues k and k¹, the gas being brought in contact at n with
forced currents of air entering through m; portions of the combustion gases not
required to enter a¹ at c are conducted off through openings i and flues r¹ formed
in the furnace walls, so as to heat these in the manner of retorts.
The mode of operating with this construction of furnace is as follows:
The column of ore or other material in a¹ becomes heated to red heat by the
flames entering through the passages c, and consequently the reducing process or
distillation of the zinc therefrom in the first instance takes place from top to
bottom in the vertical layer immediately adjoining those passages, after which it
proceeds horizontally across the mass to the front side thereof, where in like.
manner it terminates simultaneously along the entire vertical surface. While this.
D
17

page_text: is proceeding in a' the air forced in through 9 into h not only prevents the zinc
vapours from depositing in the part a of the chamber, but also effects a
supplemental reduction of the residuum material situated below the flame
passages c.
In consequence of the arrangement of the parts a¹ b c d, the mode of working is
rather that of a chamber furnace than that of a shaft or blast furnace; yet by the
combination therewith of the blast chamber h and the resulting supplemental
reducing process, resembling in its action that of the shaft or blast furnace, the
total system may be looked upon as a combination of the chamber furnace and
shaft furnace systems.
In the arrangement of zinc smelting furnace shewn respectively in cross section,
sectional front and back views and sectional plan at Figs. 1, 2, 3 and 4, the
extension Z at the front side of a contains the retorts or recipients e entering at
the inner end the openings d of the reducing chamber, and at the outer end fitting
into the tubular recipient f which has external apertures closed by doors y corre-
sponding to each of the retorts, while at bottom it is provided with the arrangements
for collecting and discharging the zinc.
From the top of f two branch passages u u lead on either side into metal
tubes f¹ in which the zinc vapours passing over from fare condensed and deposited
as zinc dust; the lower ends of these tubes communicate by side passages o with
the chamber Z, so that the uncondensed gases issuing from them into the latter,
in entering into combustion and in rising to the chimney flue at top of Z, impart
their heat to the outer surfaces of the retorts and also to the wall of the reducing
chamber.
The arrangement of the condensing apparatus shewn respectively in sectional
elevation, sectional plan and front view at Figs. 5, 6 and 7 has solely for its purpose
the obtaining of zinc powder.
The extension Z to the reducing chamber is in this case dispensed with, and in
order to facilitate cooling and condensation, the parts e¹ and fi are made of sheet
iron; they might however be of brickwork. ƒ³, as in f of the preceding arrange-
ment, is provided with openings closed by doors y; are the escape flues for the
gases. Figa 8 and 9 shew different forms of extended condensation flues for
deposit of zinc dust.
With a may also be combined the known arrangements for obtaining zinc
oxide. c. Fig. 1, is a firegrate arranged underneath ƒ for the purpose of assisting
the action of the combustion of the carbonic oxide gases entering Z through o;
v and w are doors for gaining access to the flues and passages c, i and r; 8 are
openings for the removal of ashes, conveyed through them from the flues r and r¹;
t is a passage communicating with the chimney flue into which lead openings t
for ventilating the vault of the furnace.
The determination whether only one gas producer or two thereof is or are
required for working the furnace depends upon the number and size of the reducing
chambers a¹, upon which also depends the size of the combustion chamber b, that
is, whether this should be made to extend over the back of only one or of two or
more reducing chambers. The number of retorts e to be employed will depend
upon the height of the reducing chamber a¹, and upon its width will depend
whether only a single row or two or more rows of openings d side by side leading
to the condensing apparatus are provided.
If the charging from the top through g is to be avoided as much as possible, the
charging may be effected up to the level of the top retort through the retorts
themselves. :
It will be evident that the success of this mode of operating will in great
measure depend upon the employment of the combustion chambers, because by
this arrangement not only will the production of slag be prevented but also
the presence of too large a quantity of air and carbonic acid at d and the
carrying over of injurious quantities of dust into the condensing apparatus will
be obviated.

page_text: For regulating the nature of the flame and the pressure of the gas, regulating
valves are provided on the air supply pipes and on the gas producers, and plates
are provided at m and over r for controlling the escape of the excess of gases.
Fine grained ores such as roasted zinc blend &c, may be utilised by mixing the
same with coarser ores, or coarse reduction residues in order to bring them into
Buitable condition to be worked.
Under suitable conditions the forced air supply may be replaced by the action of
chimney flues or exhaust fans.
The reducing chambers being entirely independent of each other, it will be
evident that when required only a single one or a pair of them may be used. In
the constructions of furnaces shewn by way of example on the accompanying
drawing, the height chosen for the reducing chambers a¹ is such as would per-
mit of their erection in old zinc smelting works of limited capacity; it will be
evident that any increase of the height of a¹ and consequently also of the com-
bustion chambers and condensing apparatus would result in a corresponding
increase of producing capacity, without necessitating any increase of the horizontal
dimensions.

page_text: I, LUDWIG KLEEMAN of Myslowitz, Silesia in the German Empire, Director of
Mines 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 an improved construction of furnaces for smelting zinc
ores or other materials containing zinc and to the mode of operating with the said
furnaces, which I will proceed to describe with reference to the accompanying
drawings.
The furnace consists of a larger or smaller number of reduction chambers a¹,
arranged side by side and separated by partition walls and having at top closed
charging hoppers g while their lower restricted ends a' communicate with
chambers h provided with doors in the vaults below the floor, for the removal
of the reduction residues.
At the front side of the chambers a¹ are other chambers Z of suitable height
and width containing the condensing apparatus, and communicating with a¹ through
flues or openings d d corresponding to each condensing retort e. At the back of
the reducing chambers a¹ are provided the combustion chambers b which also
communicate with a¹ by a number of superposed flues or openings c.
The combustion chambers 6 are supplied with combustible gas from gas producers
through flues kk, and with air for supporting combustion through flues m, from
which it enters the gas flues at n. Any of the gas and air in combustion that is
not required to enter a¹ through the openings c is led off through side openings i
into flues r and 7 formed in the side walls, whereby these become heated. From
the above arrangement it will be seen that the chambers a¹ being charged with
ore, that part of the column which is contiguous to the flues c of the combustion
chamber will first be heated to red heat, so that the reduction of the ore or the
driving off of the zinc vapours will commence simultaneously along the whole of
this surface from top to bottom, and will extend thence in a horizontal direction
across the column, finishing in like manner at the opposite vertical surface.
In order to prevent the escape of any of the zinc downwards into the ash
chamber, either as vapour or as condensed zinc powder, a supplemental supply of
air blast is introduced at g so as to effect a supplemental reduction of any such
descending zinc.
It may prove beneficial in practice to introduce combustible gas at h instead, of
or together with air.
In the reducing furnace shewn at Figs. 1 to 4 for obtaining zinc, the condensing
retorts e, e, contained in the chamber Z enter with their inner ends into the
openings & and with their outer ends into the tube f forming a receiver common
to all the retorts in one vertical row, and having at bottom arrangements for

page_text: collecting and discharging the condensed zinc. From the upper end of ƒ connecting
flues uu are provided, which divide the current of gases or vapours and lead them
to sheet metal tubes f¹ on either side, which serve to effect the condensation of the
zinc vapours and their deposit as zinc dust, and from the lower ends of which
flues o lead into the chamber Z in order to allow the uncondensed gases to pass
back into this chamber, where, becoming ignited, they ascend to the chimney on
the top thereof and in so doing impart their heat to the retorts e and the front wall
of the reducing chamber a. The air necessary for this combustion is admitted at x,
and if necessary through openings at the sides of the retorts. The escaping
reduction gases might also be led into the top of the chamber Z and be caused to
travel downwards therein.
The arrangements shewn at Figs. 5 to 7 have for their purpose the direct
obtaining of zinc dust. The retorts and retort chamber are here dispensed with;
and the openings d of the reducing chamber a¹ are connected either directly or by
branch pipes et with the condensing chambers f* of rectangular or other section, at
the sides of which are the supplemental condensing apparatus shewn in two modifi-
cations at Figs. 8 and 9, the construction of which may be varied. For facilitating
the cooling, is shewn of sheet metal, but it may also be of brick work. f' is
provided, similarly to f¹ with doors and sight holes y; 1 (Fig. 6) are the discharge
flues for the escaping gases. The reducing chambers a¹ may also be combined with
the known apparatus for producing zinc oxide.
In the arrangement at Figs. 1 to 4, x are fire places under the tubes f¹ for
supplying heat in addition to that supplied by the combustion of the carbonic oxide
introduced into Z at o. v and w are soot hole doors for clearing the flues C, i and
passages r. 8 are openings for the removal of the flue dust that accumulates at
those points from the passages r and r¹; t are openings in the vaults, communi-
cating with a passage t leading to the chimney, for the purpose of ventilating the
vaults. It will be evident that the successful working with this construction of
furnace will in a large measure depend upon the mode of employing the combustion
chambers, because precautions will have to be taken with these to avoid not only
the production of excessive quantities of slag but also the existance among the
combustion gases of detrimental quantities of air and carbonic acid at d, and the
carrying over of detrimental quantities of dust into the condensing apparatus.
While therefore the last named precaution as also the necessary prevention of
detrimental slag formation must determine the gaseous pressure to be employed
in b, it will also be of advantage so to conduct the combustion in b, that the gases
passing thence to a¹ and i consist mainly of carbonic oxide, in view of preventing
the presence at d of detrimental quantities of suspended air and carbonic acid.
The means for attaining this end in the manipulation of the gas producers and
combustion chambers 6 are provided for by the usual regulating devices at the gas
producers and at the air supply m, as also by the discharge of excess of gases at
the top of r, and for this purpose also, the flue m may also be connected with the
flues 7.
The complete independence of the reducing chambers from each other in regard
to the reducing operations, permit of their being either single or combined in sets.
of 2, 3, 4 or more to one and the same furnace, and of their being constructed of
any height suited for the required conditions of working. The height of the
chambers, which determines the number of superposed openings d will also deter-
mine, in combination with the width of the chambers, whether only a single row
of openings d will be sufficient for providing a¹ with the necessary condensing
apparatus, as on the drawing, or whether more than one row will be required, and
the same will also hold good as regards the openings at c.
In the construction of furnaces shewn by way of example, the employment of
existing zinc reducing works has been considered, where the reducing chambers a¹
may be made of any width and height suitable for the particular locality, the
arrangement of the furnaces in groups, as shewn, being intended to economise
space.

page_text: Two or more of the reduction chambers might be arranged in combination with
a single combustion chamber, if circumstances permit of this without detriment to
the action of the furnace.
According to circumstances, the blowing apparatus may be replaced by exhausters
or chimney draught.
As, considering the arrangement of the reducing chambers a¹ their mode of
working may be regarded rather as that of chimney furnaces than as that of shaft
furnaces, the combination of the chambers a' with a' and h may be considered to
constitute them as a combination of shaft and chimney furnaces.
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-Constructing furnaces for reducing zinc ores or other compounds of zinc, with
one or more vertical reducing chambers, one side of which is provided with one or
more vertical rows of openings c communicating with a combustion chamber, while
the opposite side is provided with one or more vertical rows of openings d commu-
nicating with the condensing apparatus whereby the process of reduction is made
to take place progressively in a transverse direction through the charge of the
furnace, substantially as herein described.
2-In the construction of reducing chamber referred to in the preceding claim,
the use of a box or chamber h closing the lower end thereof, and serving to remove
the residues, into which box air or gas is introduced at q for driving off the residual
zinc vapours, substantially as herein described.
3-The use of passages i, connecting the combustion chambers with the heating
flues in the walls of the reducing chambers, in order to utilise the surplus gases
from the combustion chambers for heating the reducing chambers substantially as
herein described.
4-In combination with the construction of reducing chambers referred to in
the first claim, the use of tubes f forming a receiver common to two or more
retorts e arranged above one another in a chamber Z substantially as herein
described.
5-In combination with the condensing apparatus referred to in the preceding
claim, or modifications thereof, the supplemental condensing apparatus such as are
shewn at Figs. 8 and 9 arranged outside the chamber Z for the condensation of the
escaping zinc vapours, with provision of means for leading the reduction gases
escaping therefrom back into the chamber Z for the purpose of heating the same
substantially as herein described.
6-The use in lieu of the condensing apparatus referred to in the preceding
claims of condensing chambers such as f* Figs. 5, 6 and 7 connected either directly
or by branch pipes e, with the reducing chambers a¹, for the purpose of directly
obtaining zinc dust, the said chambers being combined with lateral supplemental
condensing apparatus for completing the condensation of the escaping vapours
substantially as herein described.