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Патент USA US2127727

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Aug. 23, 1938.
2,127,727
K. R. GOH‘RE ET AL
ROTARY HEARTH FURNACE
Filed April _l3, 1937
5 Sheets-Shéet 1
Inventors.
KlLl/ZR. G'b'bre
Jakob Sc]: M216
Paul Jpez'c/zerf
5y 0.0% '
‘
Atlbrneg
Aug.23.'1938.
MGQHREETAL
’
‘2,127,127
ROTARY HEAR'I'H FURNACE
Filed
F1912
April '13. 1937
.
- 3?
28
‘
> 5 Sheets-Sheet
28
Paul
eic?ert
19.9 amm
A flax-neg
Aug. 23,
.
R‘ ‘GQHRE 5-;- AL
2,127,727
ROTARY HEARTH FURNACE:
Filed April 13, 1937
5 Sheets-Sheet 4
‘ In renters.
PM! 5 eicherl
B, OVWM
Attorney
Patented Aug. 23, 1938
,
- ‘ 2,127,727
UNITED STAT ES PATENT‘ OFFICE
2,127,727
ROTARY nnaa'rn FURNACE
Kurt R. Giihre, Jakob Schwalb, and Paul Spel
chert, Franki'ort-on-the-Main, Germany, as
signors to American Lurgi Corporation, New
- York, N.‘Y., a corporation of New York
- Application April 13, 1937, Serial No. 186,576
In Germany September '1, 1935
18 Claims.
(Cl. 266-20)
‘
,
,
.
1 ‘ The present invention relates to rotary hearth ~
?culties may be eliminated in a remarkably
furnaces, and, more particularly, to rotary hearth
furnaces for producing lead from sulphide ores
simple manner.
by means ‘of the roasting reaction process.
As those skilled in the art know, furnaces
having a rotatable hearth of annular form pro
vided the best ‘results in treating sulphide ores
of lead. These rotary hearth furnaces were gen
erally provided with a stationary hood which
10 extended into the close proximity of the exterior
rim _of the hearth. The hood was provided with
one or with a plurality of working openings or
doors for the treating of the charge and charging
and ‘stirring apparatus were provided at both
sides of these working doors. This arrangement
‘
It is an object of the present invention to pro
vide an improved rotary hearth furnace .which
is substantially free from the disadvantages and
inconveniences . connected
with
conventional
hearth furnaces.
Another object of the present invention is to
provide an improved rotary hearth furnace par
ticularly for the production of lead from sul 10
phide ores by means of the roasting reaction
process which substantially eliminates and preé
vents the formation of ?ying dust and of lead
fumes and the losses connected therewith.
A further object of the invention is to pro
vide a rotary hearth furnace for smelting lead
'ores involving an improved control of the air
provided such conditions that even in the case
of relatively small air leakage, the gas velocity
1
in the openings of ,the hood and in the gap blast through the charge.
It is also within the contemplation of the in
‘between the hood and the rim of the hearth was’
sufficient ‘to completely prevent the gases or .vention to provide a novel and improved rab
, fumes formed during the reaction to, escape to
bling and stirring apparatus for breaking up
the exterior. The rotary hearth furnace pro
vided a very substantial progress in the pro
duction of lead from sulphide ores in that it
eliminated the presence of poisonous fumes in
the proximity of thefurnace, increased the out
put and reduced the cost of production. It has
the charge and for the removal of incrustations
zles readily picked up small particles of the
furnaces substantial losses occurred through the
formation of ?ying dust and of lead fumes.
Particularly in proximity to the rabbles employed
for the purpose of breaking up the charge, the
air blast continuously emitted through the noz
a
substantially without vcausing the formation of '
?ying dust and of lead fumes. 1
Moreover, the invention also contemplates an 25
improved arrangement of the hood and its co
operating parts with respect to a rotatable,
hearth of annular shape in order to prevent the
formation. of irregular and eddy currents of air
within the hood and to eliminate the produc
tion of localized overheating of the charge,
formation of ?ying dust and-‘of lead fumes.
The invention likewise contemplates an im
proved rotary hearth furnace which is simple
' been found, however, that even in rotary hearth
v .)
charge and cause the production of clouds of
in construction and which may be built and
flying dust and lead fumes. _ Likewise, the rab
operated on a practical ‘and industrial scale at
bles had to be operated at a relatively high speed
a low cost.
in order to break up the charge and to remove
incrustations on the hearth in the proximity of
Other and further objects and advantages of
the invention will become apparent from, the
following description taken in conjunction with 40
40 the nozzles and the necessary quick movements
‘ i
~
,
Fig. 2 depicts a vertical sectional view of a
modi?ed embodiment of the invention, taken on
the line 2-2 of Fig. 3;
~
‘Fig. 3 shows a section taken on line 3-3 of
hood and the exterior rim of the furnace. ‘Of
We have discovered that all of the above dif
.
rotary hearth furnace embodying the principles
of the present invention;
tion and currents of the air entering through the
working doors and through the gap between the
duced the eiiiciency of rotary hearth furnaces
and prevented to fully realize all of the ad
vantages connected with the employment of the
rotary hearth principle.
.
Fig. 1 illustrates a vertical sectional view of a
45 fumes have been caused by the irregular circula-v 1
course, the losses and' other inconveniences
caused through ?ying dust and lead fumes re
'
the accompanying drawings, in which:
of the rabbles had the detrimental effect of
spraying substantial amounts of lead and to pro
duce additional amounts of ?ying dust and lead
fumes. Further amounts of ?ying dust and lead
55
20
Fig.
_
.
.
Fig. 4 is a vertical sectional view of a further
modified embodiment of the invention taken
on line 4-4401 Fig. 5;
'
.
Fig. 5 illustrates a top elevational view of the
rotary hearth furnace shown in Fig. 4;
Fig. '6 shows a fragmentary top elevational 55
2,127,727
2 .
view having parts in sectionof a portion of the
of the hearth and will set up rotation of the rods
furnace shown in Fig. 1 and illustrating the ar
around their common axis.
rangement for controlling the air blast to the
charge and for cleaning thenozzles;
the rods engages a nozzle, the passage of air
through said nozzle is greatly reduced or com
pletely prevented, so that in the region of the
rabbling apparatus no air blast is blown into the
hearth. A further important advantage of this
Fig. 7 is a similar view of the rabbling mech
anism.~
_
Fig. 8 illustrates a vertical sectional view of a
As soon as one of
further modified embodiment of the invention.
taken on .line 8--8 of Fig. 9; and
Fig.v 9 depicts a top elevational view of the
hearth shown in Fig. 8.
Broadly stated, according to the principles of
the present invention, the formation of ?ying
arrangement is that the engagement and dis
dust and of lead fumes‘ is reduced to a minimum
manual cleaning of the nozzles, which has been
engagement of the rods with the nozzles auto
matically clean the nozzles, in that charge par
ticles which entered the nozzles and incrustations
formed within the nozzles are removed by the
rods and are returned to the hearth. Thus,
or is completely eliminated by providing intermit- . absolutely necessary in prior rotary hearth fur
'tent operation of the nozzles employed for the
introduction of an air blast into the charge un
dergoing treatment. The rotatable and annular
hearth, on which the charge is progressively
20 treated much in the same manner as on an end
less belt, is provided with a large number of
tuyeres or nozzles circumferentially arranged in
the inner wall of the hearth.
Means are pro
vided for making these nozzles inoperative during
25 the time they are in immediate proximity of the
rabbling apparatus.
This removes one of the
, principal causes of flying dust and lead fumes.
, so
In addition to this, the rabbling apparatus is so
constructed and arranged that the breaking up
and the rabbling of the charge is carried out cau
tiously and at a relatively low speed without
causing spraying of the lead. Moreover, the
charging apparatus and the stationary hood lo
cated above the hearth with its gas conduits are
so constructed that the production of dust in
the newly added charge and the volatilization of
lead are greatly reduced and that the small
amounts of ?ying dust accidentally produced are
deposited already within the hood. In this man..
40 ner, the principles of the present invention make
it possible to eliminate all of the causes for the
formation of ?ying dust and for the occurrence
of volatilization of lead.
.
In the elimination of ?ying dust and of lead
45 fumes, the proper control of the nozzles is of
the greatest importance. In prior rotary hearth
furnaces, the nozzles have been generally. freed
from the covering charge materials in the por
tions of the hearth where the rabbles are break
50 ing up the charge so that the air blast from the
corresponding nozzle was blowing over the charge.
Of course, this circumstance greatly increased the
production of ?ying dust and of lead fumes. Ac
cording to the principles of the present inven
tion, this most important cause of the formation
of flying dust is eliminated by shutting off the
nozzles which are in immediate proximity of the
rabbling apparatus. Preferably, the nozzles are
shut off by means of an apparatus consisting of
a plurality _of rods which are rotatably mounted
on a common vertical shaft, for example, in the
form of a star arranged in the plane of the noz
zles. This nozzle controlling apparatus is so ar
ranged within the windbox that its axis of ro
65 tation is substantially in a vertical plane pass
ing through the axis of rotation of the hearth
and through the rabble of the rabbling appara
\ '“ tus.
The rods have such dimensions that the one
which happens to be in proximity to the rabble
70 will just about protrude through the nozzle which
is in the corresponding position. The. distance
of the free end of the rods from each other cor
responds to the distance between the nozzles so
that rotation of the hearth will cause succes
75 sive engagement of the rods-with the nozzles
naces, is completely eliminated and the servicing
and supervision of the furnace are greatly facili
tated.
,
In order to further reduce the formation of
lead fumes in the proximity of the rabbling ap 20
paratus, the invention provides an improved rab
bling apparatus which permits relatively slow
operation of the rabbles. As those skilled in the
art know, the object of the rabbles in the‘ hearth
furnaces of the type contemplated is not merely
to break up the charge but also to remove the
incrustations formed on the back wall of the
hearth in the proximity of the nozzles. This ob
ject can be accomplished only if the rabble
sweeps over all of the surface of the back wall of 30
the hearth during the time the portion of the
rotating hearth is within the reach of the rab
ble. Generally speaking, in the operation of ro
tary ‘hearth'furnaces it is highly' desirable to
maintain relatively fast rotation of ‘the hearth in 35
order to obtain a high output.
Of course, under
these operating conditions it is necessary to make
the rabble relatively wide and to operate. the
same at a high speed, because otherwise it would
be impossible to obtain overlapping of the in 40
dividual rabble strokes on the surface of'the
hearth. The great width and the fast operation
of the rabble, however, has ‘the disadvantage that
substantial amounts of lead are sprayed about
and that simultaneously with the breaking up of 45
the charge very great ‘ quantities of dust are
formed.
In order to eliminate also this cause of the
formation of dust andndiefumes, the presentin
vention provides a plurality of rabbles, generally 50
two, arranged in close proximity of each other.
Preferably, the rabbles are‘relatively narrow and
are operated alternately. This makes it possible
.to operate the rabbles at a relatively low- speed
so that splashing ~or- spraying of the lead is
avoided and a cautious but completely satis
factory breaking up of the charge is obtained.
It is preferred to provide the rabbles at a slight
distance from each other and to operate them
by means of individual eccentrics removably con
nected to a common drive. This makes it possible
to individually disconnect each rabble and to re
8.0
move the same from the charge for the pur
poses of inspection, repair, or replacement.
Thus, the furnace embodying the principles of 65
the invention successfully eliminates the princi
pal causes of the formation of dust and of fumes
and the only remaining possibility of the forma
tion of dust .and of fumes is in the irregular
movement or streaming of the air entering 70
through the working doors and through the gap
‘between the hood and the exterior rim of the
furnace, the so-called'air leakage, or false draft.
Damming up of this air and the formation vof
eddy currents therein may cause picking up of 76
2,127,727
3
increasedpuantities of dust from the charge operating temperatures have vthe disadvantage
dropped'onto the‘ hearth. Moreover, it can easily
that not only the volatilization of lead but also
happen that certain portions of the hearth are “ the formation of slag are greatly increased and
not suiliciently exposed to the’eil’ect of this draft
which may cause localized overheating of the
. charge and consequently volatiiization of sub
stantial quantities- of lead. According to the
principles of the invention. this further source
of the, formation of ?ying dust is eliminated by
the output of metal is considerably lowered. In
rotary hearth furnaces generally, water cooling
is provided for the back wall of the hearth for
the purpose of reducing the working tempera
tures and for carrying away heat from the
charge. This cooling is further supplemented by
the cooling effect of the air entering from the 10
outside underneath the hood. According to the
present invention, the intimate contact of this
air with the charge and thereby emcient cooling
means of ‘the special construction and' arrange
ment of the hood, of the gas outlets through
which the furnace gases leave the hood and of
the charging apparatus so that uniform stream
ing of the gases in the hood is maintained ‘and conditions are‘ obtained by the special arrange
.15 the newly added charge material is not exposed ment and construction of the hood and of the 15
to strong currents of gas.
-gas outlets.’ Since in the prior rotary hearth
Thus, for example, the fresh charge material furnaces the major portion of the air is intro
consisting of well moistened ore mixed in a suit
duced through the working door into the hood,
in the rotary hearth furnace embodying the in
able proportion with coal- may be fed to an an
20 nular charging plate provided within‘ or without vention and employing only one working ‘door, 20
the hood and rotating with the hearth. This this door ‘is located at one side and the gas out
charging plate is only at a slightly higher level let at the other side of the furnace ring so that
than the charge material on the hearth so that
the gas outlet is provided in the portion of the ~
the height of fall from the charging‘ plate to -. hood directly opposite to the working door.
the hearth is very low and is incapable of caus-~ Thus the air entering through the working door 25
ing the production of ?ying dust. In addition is uniformly distributed to both sides and a uni
. to this, premature drying 'out of the charge ma- form gas stream is developed above each half of
terial in, the charging apparatus is prevented by the hearth between each working door and'gas
‘ providing the discharge end of the charging bin outlet without having obstacles in the path of
or hopper feeding the material to the ‘charging these streams and without causing any eddy cur~ 30
plate ‘immediately before the‘ device which rents which facilitate the production of ?ying
throws the material or ore from vthe charging dust. The hood may be made large enough to
plate onto the hearth. This arrangement is considerably reduce the velocity of the gas stream
_
especially preferred in hearth furnaces of large within the hood.
35 size where the charge is fed simultaneously to '
Likewise, and in consideration of the same OF
the hearth at a plurality of points. It is of ad
vantage to provide the charging bin with a plu
principles, in a hearth having a plurality of
working doors, the outlets i'orv the furnace gases
rality of adjustable discharge openings which, if
desired, may be completely disconnected or shut
are preferably provided approximately half way
between two successive working doors. . This
In smaller hearth furnaces where the
charge is fed at a single point, insteadof the
above arrangement, a stationary charging de
makes it possibleto obtain the most favorable 40
conditions for the streaming of the gases and for
vice mounted on the inner or outer side of the
tained that in this manner ‘the formation of fly
ing dust and particularly the volatilization of lead
are still further reduced.» Increasing. the size of 45
the hood has the further advantage that a great
40 oil’.
hood may be employed,1 which is provided with
45 discharge discs and which is completely encased.
In all cases the charge material from the charg
ing plate or disc may’ be conducted through
\' pipes or slide surfaces to the charge material
' on the hearth whereby the possibility of dust
50 formation is still further reduced.
In the case’ when ores causing very high tem
peratures during the operation of the furnace
are employed, it is of advantage to avoid throw
ing the fresh ‘charge material on the charge
the dissipation of the heat.
It has been ascer
part of the ?ying dust possibly formed'is sepa- '
rated from the gases within the hood and falls
directly back on the charge in the hearth. The
separation of dust in hot condition above the 50
hearth can be further promoted by special con
struction or shape of the hood. These conditions
may be obtained, for example, by subdividing
the inner space of the hood in the form of a
‘cyclone separator or ‘by changing the direction 55
charge into the old and partly treated material. or speed of the stream of waste gases within the
hood. Thus, the space within the hood may be
To this purpose the charging of the fresh mate
rial is provided in the region of the working subdivided by means of an inclined annular wall.
55 present on the hearth and to embed the fresh
door so that the freshly added charge falls in
60 proximity of the back wall of the hearth on top
of the broken up charge where the removal of
the slag is approximately finished. By return
ing the portions of the charge which during the
breaking up operation have been displaced to
65 wards the exterior rim of the hearth and into
their former position, this returned charge will
kcover the freshly added and cold charge mate
\i-ial. Preferably, this procedure is carried out
manually by the smelter in charge of the hearth
70 with a scraper, in the same manner as in the
At suitable portions of the wall openings may be
provided for the passage of the gases from the '
lower space or portion of the hood into the upper
space thereof and the gas outlet pipes are con
nected to suitable portions of the upper ‘space.
The dust deposited in the upper space of the
hood is returned to the hearth by means of small 85
slots in said inclined annular wall which are
preferably arranged in the proximity of the
cooled wall of the hearth. The same results,_
to wit: returning the dust to the hearth, may be 70
*obtainecf
by providing a relatively low hood in
conventional manually operated simple lead
,hearths. Thereby the intermediate and the ‘ combination with high and very wide gas outlet
pipes, (Fig. 5) 28 above the hood. These gas
lower portions. of the charge are cooled and ex
cessive temperatures within the charge are outlet pipes act in the manner of a dust chamber
75. avoided. As those skilled in the art know, man so that part of the dust contained in the gases 75
4
2,127,727
is deposited therein and is returned to the charge
In case more than two working doors are em
on the hearth.
For the purpose of giving one skilled in the
art a better understanding of the invention, a
ployed, the number of gas outlet pipes is in
creased accordingly.
In order to maintain the ,
lead bath in the hearth at a substantially uni
preferred embodiment will be described in con
form level throughout the operation of the rotary
junction with the accompanying drawings.
hearth furnace, a circular channel 48 is pro
vided around the hearth. The lead discharged
from the hearth through discharge spout 63
Referring more particularly to Fig. 1, an an
nular hearth I is rotatably mounted by means
of rails 2 on rollers 3.
Hearth I is driven by
means of a motor (not shown) and a. reducing
gear II through a pinion 39 and crown wheel 4.
Nozzles 5 are provided around the circumference
of the hearth and are supplied with blasting air
through a wind box 6 connected to the hearth
15 and rotating therewith. Wind box '6 is in turn
supplied with air through a centrally located
stationary pipe ‘I located underneath the wind
box. Stationary air pipe is connected to a suit
able source of air such as blower, or the like
20 having a conduit discharging into pipe ‘I through
an opening 8. The air pipe is provided with a
man hole 62, through which the inside of the
pipe is accessible for inspection and cleaning.
Hearth I’ is centered and wind box 6 is con
25 nected to pipe ‘I in a substantially air tight man
ner through sliding surfaces 9 and packing seal
III. A support IB bearing the rotatably mounted
rods I‘! and I8 is secured to the upper end of
the stationary air supply pipe ‘I in such a man
30 ner that its axis of rotation is approximately in
the same vertical plane as the rabbles I2 and I3
of a‘ rabbling apparatus I4. This will cause rods
?ows into channel 48 and ?nally arrives into a
collecting and casting receptacle 49. The ore
in admixture with carbonaceousmaterials and in
some cases with other additional reducing
agents, is introduced in conventional manner
onto an annular charging plate 59 rotated with
the’ hearth and is charged from this plate to the
hearth. The outer edge of the hearth is pro
vided with a working plate 64 which facilitates
the removal of slag from the broken up charge.
The relatively high and wide hood, such as
26 in Fig. 1, is particularly advantageous in
smaller furnaces. In rotary hearth furnaces of
larger size the hood may be constructed in the
form illustrated in Figs. 2 and 3. From the illus
tration of this modified embodiment of the in
vention the drive for rotating the hearth, the air
conduits'and the device for controlling the noz
zles have been omitted for the sake of sim
plcity.
The air entering through the working
doors 51 and the furnace gases are conducted
in a regulated stream over the hearth and rise .
into the upper portion of the hood through open
ings 58. The upper portion of the hood is de
?ned by plates 29, 30, 3| and 32. Openings 58
I'I, I8, etc. to successively engage and disen
gage corresponding nozzles in the hearth and
will close the nozzles during the time when they
pass by the rabbles and if necessary also during
hearth portion between the two working doors;
the time the nozzles are in the region or in a
working doors. In this form of the hood the gases
part of the region of the working door. Further
similar devices for intermittently shutting off the
40 nozzles may be provided at other portions of the
‘furnace, if necessary.
_
The operation of these devices for controlling
the nozzles may be more completely understood
by referring to Fig. 6 illustrating a top eleva
45 tional view of the device for closing and clean
ing the nozzles and a sectional view of the
hearth wall taken in the plane of the nozzles. A
. vertical shaft I5 around which rod supporting
member I6 bearing rods I1, I8 and I9 is mount
ed, is rotatably supported in a bracket 20, which
50
is rigidly connected to pipe ‘I. Rod I8 is shown
being within conically shaped nozzle 2I, while.
rod ll just begins to enter nozzle 22 and rod
I9 leaves nozzle 23. The rotation of hearth I
55 will cause the nozzles H to engage and displace
rod I8 until the next rod I‘! completely engages
nozzle 22. Thus. the rotation of the rods and of
their support is caused and is directly controlled
by the rotation of the hearth. This arrange
60 ment has the great advantage of providing posi
tive control and closing of the nozzles and at the
same time deposits and incrustations within the
nozzles are automatically removed and returned
to the hearth and cannot drop into the wind
65 box. In other words, the device provides posi
tive control and automatic cleaning of the noz
zles in a simple and foolproof manner.
Hearth I of the furnace is provided with a
water cooled back wall 24' which rotates with the
hearth. A gas tight joint between back wall
24 and the inner wall 25 of stationary hood 26 is
provided by means of a water or sand seal 21.
The gases are removed from the hood through
wide gas outlet pipes 28 which are mounted in
75 the cover of the hood between two working doors.
are located approximately above the middle of the
whereas the gas outlets 28 are located above the
not only provide good cooling of the charge on
the hood but at the same time due to the change
in the direction of their streaming and in their 40
velocity and due to their re?ection, most of the
dust carried by the gases is precipitated. The
precipitated dust slides downwards along in
clined surfaces 28 and 30 and arrives at a gap
33 through which it drops back on top of the
material on the hearth. Gas outlet pipes 28 are
extended into the upper space of the hood so
that a streaming of the gases is produced simi
lar to that prevailing in cyclone separators
whereby the precipitation of dust is still further
improved. The hearth is provided with a rab
bling apparatus i4 having a pair of rabbles I2
and i 3.
In the modified embodiment of the invention
shown in Figs. 4 and 5 a relatively low hood 26 .
is employed, which will cause substantially higher
velocities of the gases above the hearth. The
precipitation of dust is performed in the very
high and wide gas outlet pipes 28 which in addi
tion may be constructed in the manner of a
cyclone separator. Preferably, the device'con
veying the charge to the hearth is provided in
close proximity to the hearth. A low cooling
sleeve 24 carries a charging ring 34 on which
the ore is deposited by the discharge openings 35 (i5
of the charging bin. Discharge openings 35 and
the conduits associated therewith are of a quad
ratic cross section and extend through cover 52
of the dust collecting hood approximately to the
charging ring. Looking in the direction of hearth 70
rotation, in the back wall of each charging outlet
there is an opening cut out, the free width of
which may be adjusted by means of a slide 36.
Slide-36 may be opened to a smaller or, greater
extent, or may be completely closed by means of 75
5 .
‘ 2,127,727
a threaded spindle 6|. The charge material. is
for intermittently and successively shutting off
the passage of air through said nozzles.
3. A rotary hearth furnace for the production
of lead from sulphide ores comprising an annular
rotary hearth, a‘ stationary hood above said
CR device are accessible through the air pipe which hearth, said hood extending close to the‘ outer
is. preferably provided with man holes, similar to
element 62 in Fig. 1- In the hearth furnaces rim of the hearth, at least one rabble arm ex
illustrated in Figs. 1 and 2, the ‘space above the tending through said hood to said hearth, a
wind box may be open and separated from the windbox in the center of the hearth, a plurality oi."
gas space above the hearth by means of an inner nozzles associated with the inner rim of said 10
wall 25 and 3i, respectively; so that it is possible hearth at spaced intervals of the circumference
to arrange the charging apparatus and the con- ‘ thereof in communication with vsaid windbox,
duits for the cooling water in this space. In some means for maintaining said hearth in continuous
cases it is of advantage to provide a sheet metal rotation, and means for intermittently shutting
ring 31 around the outer wall of the hood whereby off the ‘passage of air through said nozzles during 15
the streaming of air along the outer surface of the time they are in proximity of said rabble
thrown on the hearth by means of a scraper60
shortly after it has been deposited on the charg
ing ring. The wind box and the nozzle cleaning
‘ the hood is regulated and the cooling of the outer
arms.
.
4. A rotary hearth furnace for the production‘
of lead from sulphide ores comprising an an
nular rotary hearth, a stationary hood above said 20
side of the hearth. ’
‘
hearth,
said hood extending close to the outer
Fig. 7 is a detail view of the rabbling apparatus
l4 for actuating rabbles l2 and “I3. .A pair of rim of the hearth, at least one rabble arm extend
ing through said hood to said hearth, a windbox
discs or ecce'ntrics_40 and 4| is provided, support
ing rabbles l2 and I3 displaced by about 180° in the center of the hearth, a plurality of nozzles
with respect to each other. Discs 40 and 4| are associated with the inner rim of said hearth at 25
rotated by means of a motor 42, through a reduc-' spaced intervals of the circumference thereof in
ing gear 43, a shaft 44 and drive wheels 45 and 46 / communication with said windbox, a rotatable
of which one, wheel 46, may be disengaged by member in said windbox, and a plurality of rods
means of a clutch 41. The speed of rotation of radially and equidistantlally mounted on said
30'
discs 46 and 4| and therotation' of the hearth member, said rods being ‘adapted to engage said
are so adjusted that the strokes of the rabbles nozzles during rotation of said hearth and to im
overlap and that all of the surface of the hearth part rotary displacement to said member for in
and the charge therein are uniformly subjected termittently shutting off and to clean said
wall is ftu'ther promoted. A rabbling apparatus
l4 having rabbles l2 and His provided at one
20
25
'
30
‘
to,the rabbling treatment.
'
nozzles.
.
The rotary hearth furnace illustrated in Figs.
35
8 and 9 is similar in construction to the ones
shown in Figs. 1 to '7 and similar reference char
acters are used to denote corresponding parts.
.
5. A rotary hearth furnace for the production 35
of lead from sulphide ores comprising an annular
rotary hearth, a. stationary hood above said
hearth, said hood extending close to the outer
This hearth is provided with‘ a single charging , rim of the hearth, at least one rabble arm ex
40 apparatus 66. The ore is charged from a bunker
66 into a tube 68 through the intermediary of a
discharge plate 61 arranged within a closed hous
ing 66. Tube 68 is carried through hood 26 of the
hearth which extends downwardly almost to the
45 hearth. This hearth furnace is provided with a
single working door 69. Opposite to the working
door 691s located draw-off ‘ill for the hearth,
gases. Thus, the air introduced underneath the
hood through working door 69 is divided into two
branches streaming right and left towards draw
150 off 10 above the twmhalves of the hearth. These
.two branches of‘ streaming air take up the hearth
gases and are again united after leaving the
-
hearth.
.55, 1. A rotary hearth furnace for the production
We
claim:
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of lead from sulphide ores comprising an annular
‘ rotary hearth, a stationary hood above said"
tending through said hood to said hearth, a 40
windbox in the center of the hearth, a plurality
of nozzles associated with the inner rim of said
hearth at spaced intervals of the circumference
thereof in communication with said windbox,
means for maintaining said hearth in continuous 45
rotation, a rotatable member in said windbox, a'
shaft for said member located substantially in
the plane of said rabble arm, and a plurality of
rods radially and equidistantially mounted on
said member, said rods being adapted to be en 50
gaged by said nozzles during ‘rotation of said
hearth and to impart rotary displacement to said
members for successively and intermittently
shutting off and for cleaning the nozzles within
the. region of said rabble arm.
65
6. A rotary hearth for the production of lead
from sulphide ores comprising an annular rotary
hearth, a stationary hood above said hearth ex
tending close to the outer-rim thereof, a windbox
in the center of said hearth, a windpipe communi
cating with said windbox and coaxial therewith,
hearth, a plurality of nozzles operatively asso
ciated with said'windbox and opening. on to the a plurality of tapering nozzles associated with the
hearth, rabble arms extending through said hood inner rim of said hearth at spaced intervals of
to said'hearth, and means for intermittently and the circumference thereof in communication with 65
successively controlling the . passage of air
said windbox, rabble arms extending through
through said nozzles.
_
said hood to said hearth, a rotatable member in
2. A rotary hearth furnace for the production said windbox, a vertical shaft for said member
of lead from sulphide ores comprising an ‘an: mounted on said windpipe substantially in the
nular rotary hearth, a stationary hood above said plane of said rabble arms, and a plurality of rods
70
70 hearth, said hood extending close to the outer radially and equidistantially mounted’ on said
rim of the hearth, a wind-box in the center of the member, said rods being adapted to be engaged by
hearth, at least one rabble arm extending through
said nozzles during rotation of said hearth where
, said hood to said hearth, a plurality of nozzles by a rotary displacement will be imparted to said
associated with the inner rim of said ‘hearth and ‘
members and, the nozzles within the region of
hearth, said hood extending close to the outer
60 rim of the hearth, a windbox in the center of the
“:15
in Communication with said windbox, and means
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2,127,727
said rabble arms will be positively and auto
matically controlled and cleaned.
7. A rotary hearth furnace for the production
of lead from sulphide ores comprising an annular
rotary hearth, -a stationary hood above said
hearth extending close to the outer rim thereof,
a windbox in the center of the hearth, a plurality
of nozzles associated with the inner rim of said
hearth at spaced intervals of the circumference
10 thereof in communication with said windbox, at
least one rabbling device located in proximity
of said hood, a pair of rabble arms associated
means for charging ore to said hearth, means
for discharging lead therefrom, and at least one
working door for handling the charge on the
hearth.
11. A rotary hearth furnace for carrying out 5
a continuous roasting reaction process comprising
an annular hearth of substantially semi-circular
cross section, a stationary hood above the hearth,
a rabbling device including a pair of rabbling
arms alternately actuated by a pair of eccentrics 10
and extending through the hood to the hearth,
a windbox in the center of the hearth, a plurality
with said rabbling device and extending through
an opening in said hood to said hearth in close
proximity to each other, a roller underneath said
of tapered nozzles associated with the inner rim '
able disc for each of said arms for reciprocatingly
the passage of air through the nozzles within the
region of said rabbling arms, means for charging
of said hearth and in communication with said
windbox, means including a rotatable member 15
opening for each of said rabble arms for slidably ' and a plurality of radially arranged rods thereon
supporting the same, means including a rotat
for intermittently and successively shutting off
and alternately actuating said arms, means for
maintaining said hearth in continuous rotation,
ore to said hearth, means for discharging roasted 20
and means for intermittently shutting off the reaction products therefrom, and at least one
passage of air through said nozzles during the working door for handling the charge on the
time they are in proximity to said rabble arms. hearth.
,
8. A rotary hearth furnace for the production
12. A rotary hearth furnace for carrying out
of lead from sulphide ores comprising an annular a continuous roasting reaction process com 25
rotary hearth, a stationary hood above said prising an annular hearth of substantially semi
hearth extending close to the outer rim thereof, - circular cross section, a stationary hood above
a windbox in the center of the hearth, a plurality the hearth, a rabbling device includinga pair
of nozzles associated with the inner rim of said of rabbling arms alternately actuated by a pair‘
30 hearth at spaced intervals of the circumference
of eccentrics ,and extending through the hood to 30
thereof in communication with said windbox, at the hearth, a windbox in the center of the hearth,
least one rabbling device located in proximity of a plurality of tapered nozzles associated with
saidhood. a shaft associated with said device, a the inner rim of said hearth and in communi
pair of eccentrics driven by said shaft, a rabble cation with said windbox, means for controlling
arm for each of said eccentrics having one of its the passage of air through said nozzles in ac 35
ends connected to‘ said eccentric and having its cordance with the rotation of said hearth, an
other end extending through an opening in said annular charging plate arranged at a slight
hood to said hearth, said rabble arms being lo
height above the hearth and rotatingwith said
cated in close proximity to each other, a roller hearth, a charging hopper for depositing charge
underneath said opening for slideably supporting material on said charging plate, and a scraper 40
said arms, means for driving said shaft for recip
for stripping oif said material from said plate
rocatingly and alternately actuating said arms, and to deposit said material on‘ the hearth.
means for maintaining said hearth in continuous
13. A rotary hearth furnace for the produc
rotation, and means for intermittently shutting tion of lead from sulphide ores comprising an
-oif the passage of air through said nozzles during annular rotary hearth,’ a stationary hood above 45
the time they are in proximity to said‘? abble said hearth extending close to the outer rim of
the hearth, a- windbox in the center of the
9.v A rotary hearth furnace for the production hearth, a plurality of nozzles associated with
of lead from sulphide ores comprising an an
the inner rim of said hearth in communication
nular rotary hearth, a- stationary hood above said with said windbox, rabble arms extending
hearth extending close to the outer rim thereof, through said hood to said hearth, means .for
a windbox in the center of ,the hearth, a plurality intermittently shutting o?’ air through said noz
of nozzles associated with the inner rim of said zles during the time they are in proximity of
hearth at spaced intervals of the circumference said rabble arms, partition walls separating said
thereof in communication with said windbox, a hood into an upper and-a lower portion, work
~ rabbling device having at least_two rabble arms ing doors in said lower portion for handling the
extending» through said hood to said hearth in charge on the hearth, gas outlet pipes extend
close proximity to each other, means for recipro
ing into said upper portion, and openings in said
catingly and alternately actuating said rabble partition walls for permitting the passage of
60 arms, means for maintaining said hearth in con
gases from said lower into said upper portion 60
tinuous rotation, and means for intermittently of the hood.
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shutting off the passage of air through said noz
14. A rotary hearth furnace for the-produc
zles during the time they are in proximity of said tion of lead from sulphide ores comprising an
rabble arms.
annuiar‘rotary hearth, a stationaryhood above
10. A rotary hearth furnace for the production said hearth extending close to the outer rim of 65
of lead from sulphide ores comprising an an
the hearth, a windbox in the center of the hearth,
nular rotary hearth, a stationary h od above a plurality of nozzles associated with the inner
said hearth, said hood extending clove to the rim of said‘ hearthin communication with said
outer rim of the hearth, a windbox in the center windbox, rabble arms extending through said
of the hearth, at least one rabble arm extending hood to said hearth, means for intermittently 70
through said hood to said hearth, a plurality of shutting of! air through said nozzles during the
nozzles associated with‘ the inner rim of said time they are in proximity of said rabble arms,
hearth and in communication with said windbox,_ ‘inclined partition walls separating said hood into
means for intermittently and successively shut
an upper and a lower portion, working‘ doors
75 ting off the passage of air through said nozzles. in said lower portion for‘ handling the charge 75
arms.
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2,127,727
on‘the hearth, gas outlet pipes‘ extending into
said upper portion, openings in said partition
walls to establish communication between said
upper and lower portions, and a gap in the
Or lowermost portion of said inclined partition
walls for returning precipitated dust to the
hearth.
15. A rotary hearth furnace for the production of lead from sulphide ores comprising an
10 annular rotary hearth, a stationary hood above
working doors, and adapted to cause the precip
itation of dust therein.
17. A rotary hearth furnace for the produc?
tion of lead from sulphide ores ‘comprising an
annularrotary hearth, a relatively low station
ary hood above said hearth adapted to cause
high gas velocities, a windbox in the center of
the hearth, a plurality of nozzles associated with
the inner rim of said hearth in communication
with said windbox, rabble arms extending
said hearth extending close to the outer rim of
the hearth, a windbox in the center of the
hearth, av plurality of nozzles associated with
the inner rim of said hearth in communication
15 with said windbox, rabble arms extending
through said 'hood to said hearth, means for
intermittently shutting off air through said noz--v
termittently shutting o? air through said nozzles
during the time they are in proximity of said
said hood, said pipes being constructed in the
form of a cyclone separator and being adapted
rabble arms, inclined annular partition walls
dividing said hood into an upper annular por
tion and a lower annular portion, working doors
to precipitate dust therein.
zles during the time they are in proximity of
said rabble arms, working doors in said hood for
handling the charge on the hearth, and high gas
through said hood to said hearth, means for in- ' outlet pipes‘protruding. into the top portion of
“ 20
‘
18. A rotary hearth furnace for the produc
20
tion of lead from sulphide ores comprising an
annular rotary hearth, a relatively low station
in said lower portion for handling the charge
on the hearth, gas outlet pipes extending into ' ary hood above said hearth adapted to cause
said upper portion, openings in said partition high gas velocities, a windbox in the center of
the hearth, a plurality of nozzles associated with 25
25 walls arranged equidistantiaily from said work
ing doors to establish communication between the inner rim of said hearth in communication _
said upper and lower portions, and a gap in the with said windbox,‘ rabble arms extending
lowermost portion of said inclined partition through said hood to said hearth, means for inwalls for returning precipitated dust to the’ termittently shutting 01f air through said noz
zles during the time they are in proximity of 30
v
30 hearth;
said rabble arms, working doors in said hood for
16. A rotary hearth furnace for the produc
tion of lead from sulphide ores comprising an handling the charge on the hearth, high gas
outlet pipes protruding into the top portion of
annular rotary hearth, a relatively low station
ary hood above said hearth adapted to cause said hood located equidistantially from said
high' gas velocities, a windbox in the center of working doors and adapted to cause the deposi
- the hearth, a plurality of nozzles associated with tion of dust therein, a charging hopper for feed
the inner rim of said hearth in communication
ing ore to said. hearth, a ledge rotating with said
with said vwindbox, rabblev arms extending
through said hood to said hearth, means for in
termittently shutting off air through said nozzles
during the time they are in proximity of said
the hearth upon which-the ore is deposited from
said hopper, and an adjustable scraper for scrap 40
ing ore from said ledge on to said hearth.
hearth and arranged at a slight height above
rabblev arms, working doors in said hood for
handling the charge on the hearth,v and high
gas outlet pipes protruding into the top portion
45 of said hood located equidistantiallyfrom said
KURT R. GoHRE.
JAKOB SCHWALB.
PAUL SPEICHERT.
45
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