IMPROVEMENTS IN CALCINING AND SMELTING ORES, AND IN FURNACES AND APPARATUS EMPLOYED IN CONNECTION THEREWITH, WHICH FURNACES ARE ALSO APPLICABLE TO OTHER PURPOSES
Year: 1869

page_text: LETTERS PATENT to Charles William Siemens, of No. 3, Great George
Street, Westminster, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN CALCINING AND SMELTING ORES, AND IN FURNACES AND
APPARATUS EMPLOYED IN CONNECTION THEREWITH, WHICH FURNACES ARE ALSO
APPLICABLE TO OTHER PURPOSES."
Sealed the 30th July 1869, and dated the 21st May 1869.
PROVISIONAL SPECIFICATION left by the said Charles William
Siemens at the Oflice of the Commissioners of Patents, with his
Petition, on the 21st May 1869.
1, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street, West-
minster, in the County of Middlesex, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN CALCINING AND SMELTING ORES, AND IN
FURNACES AND APPARATUS EMPLOYED IN CONNECTION THEREWITH, WHICH FURNACES
ARE ALSO APPLICABLE TO OTHER PURPOSES," to be as follows:-
If iron or other metallic ores contain water of hydration, carbonic
acid, sulphur, or other volatile constituents, they are generally roasted

page_text: or calcined in kilus or upon the bed of a long reverberatory furnace.
The calcining kiln has the advantage of greater simplicity, but is only
applicable to ore in pieces of such size that the flame can circulate
between them, whereas the calcining furnace has to be resorted to in
dealing with ores of small grain or of a friable nature. The latter
process has the advantage that no residual matter resulting from the
combustion of solid fuel is mixed with the ore, and that the temperature
and time of operation can be varied at will, but on the other hand it
involves a considerable amount of attention and manual labour in
turning the ore. To avoid this it has also already been proposed to
calcine the ore in rotating cylinders.
The first part of my Invention consists in effecting the calcination
of metallic ores and also the burning of such substances, as cement,
lime, or plaster of Paris in a drum or cylinder of iron lined with hollow
fire-brick forming longitudinal channels, which is mounted upon rollers
and is made to rotate round its horizontal axis. The ores or substances
to be burnt are introduced through a slanting hopper at one extremity
of the rotating drum, and being worked gradually forward by the
rotation under the influence of heat, they drop in a continuous manner
from the other open extremity into a stationary close receiver or chamber,
whence they can be removed at pleasure. A smoke box communi-
cating with a chimney is fitted to the extremity of the cylinder where
the ores enter, and a current of air is induced by the chimney to pass
through an outer jacket of the smoke box and through the longitudinal
channels in the lining of the drum itself to the ore receiving chamber,
where it is met while in a heated condition by a current or currents of
combustible gas, which has by preference also been previously heated
by passing through a jacket surrounding the receiving chamber. The
flame thus resulting at or near the extremity of the exit of the rotating
drum passes through the same (heating the ore) and thence through
the smoke box to the chimney, being by that time thoroughly deprived
of heat by the cold incoming ore and the incoming air in the smoke
box jacket.
The combustible gases employed may be derived from a blast furnace
or from a gas producer such as described in the Specification to my
former Letters Patent, No. 167 of 1861, and No. 3018 of 1864; or liquid
fuel or solid fuel in form of powder may be employed, which is
forced in by a jet of steam or a current of air under pressure. If the

page_text: volatile substance to be removed from the ore or other substances is
carbonic acid or moisture a sufficient supply of gas must be admitted
to raise its temperature near the exit to the requisite degree, but the
supply of gas may be very much reduced and may even be stopped
ontirely if sulphur is emitted from the ore in considerable quantity.
The sulphurous acid produced in that case may be condensed or utilized
by passing the products of combustion through a scrubber or through
lead chambers on their way to the chimney or to an exhausting appa-
ratus, or a jet of water may be introduced at the bottom of the smoke
box for condensing the gases. By leading the combustible gas or its
substitute of liquid or solid fuel forward through a pipe into the rotating
drum the combustion may be conveniently made to take place at a
point at some distance from the exit end of the drum, in order to expose
the calcined ore finally to the chemical action of the uncombined
oxygen of the air passing in, and to impart additional heat to the air
and gas before entering into combustion. By the accumulative action
thus set up the maximum temperature within the rotating drum may
be raised even to a white heat. If the ores contain such foreign
substances as may be rendered volatile or soluble by the chemical
reaction of another substance under the influence of heat, such other
substance may be charged in with the ore in the requisite proportion.
Thus, for instance, if the iron ore under treatment contains copper,
common salt may be added and the chloride of copper produced may
be separated by levigating the calcined ore, which may be made to
fall through a spout from the revolving drum into a cistern filled with
water, whence it is raised by a Jacob's ladder to the platform or
hopper of the smelting furnace, being at the same time subjected to
the action of a shower bath of fresh water for removing therefrom all
soluble matter, and the copper dissolved in the bath may be separated
from time to time by well known processes.
In cases where the calcined ores have not to be washed but are
intended to be smelted or reduced into the metallic state, I prefer
to place the calcining cylinder above the smelting or reducing furnace,
in order to save the heat residing in the calcined ore for the succeeding
operation. Thus these calciners may be placed on the top of a blast
furnace or over the receiving hopper of the ore reducing apparatus
described in the Specification to.my Patent, No. 1892 of 1868, for the
manufacture of cast steel from the ore.

page_text: If the ore to be calcined contains sulphur or phosphorus, I mix the
same with, say, 10 per cent. of solid carbon such as coke or anthracite
in order to effect its partial reduction. At the same time I direct a
divided current of steam through the mass of highly heated calcined
ore accumulating in the close receiver before alluded to, which steam
being highly superheated will be decomposed in contact with the
heated reduced metal and carbon, liberating nascent hydrogen which
will combine with the phosphorus and sulphur, carrying off these
objectionable admixtures of the ore.
If I want to produce pulverulent metallic iron I combine the
calciner above described with the rotating ore reducing apparatus
described in my former Patent just alluded to, the reduced ore being
made to fall into a closed metallic chamber which is cooled externally
by currents of water or, gases, and which is provided with doors at
the lower extremity for the removal of the pulverulent iron after it
has had time to cool to prevent its taking fire when brought into
contact with the atmospheric air.
The calcining apparatus before described is also particularly applicable
to zinc ores. These ores.may be mixed with carbon and distilled in
the usual manner, but I prefer to employ inclined retorts opening at
both ends so as to admit of being charged and discharged in a con-
tinuous manner. These retorts are arranged in double rows in a
regenerative gas furnace of a special construction resting with their
inclined sides against the central longitudinal wall in the middle of
the furnace. Into this wall passages rise from the four regenerators,
such passages terminating in orifices facing the two opposite working
sides of the furnace, the gas and air passages being arranged alternately.
The heated air and gas in issuing in parallel streams towards the
working side, which is for the time being the front of the furnace, and
rising between the retorts, enter only gradually into combustion and
diffuse a uniform and gentle heat throughout the furnace.
The gases
turn over the middle wall towards the back of the furnace, where after
descending between the second row of retorts they escape promiscuously
through the second set of air and gas passages, and through the second
pair of regenerators downward towards the chimney. On reversing
periodically the furnace valves the direction of the flame through the
furnace is also reversed. Instead of using inclined retorts arranged
for being charged in a continuous manner, one or more tiers of ordinary

page_text: Silesian or Belgian retorts may be so arranged in the furnace that the
ends of the retorts farthest from the two working sides may be supported
upon the before mentioned central wall through which the gases are
introduced and withdrawn alternately. The space below the retorts
where the gases meet serves also to receive pieces of broken retorts
which can be readily removed from time to time through doors in the
front and back of the furnace. The same arrangement of furnace,
having a middle wall into which two sets of alternating gas and air
passages rise with orifices facing the two working sides of the furnace,
is also applicable with great advantage to other purposes, such as
heating gas retorts or heating the pots for melting glass. Two rows of
glass pots being placed upon sieges on either side of the central wall,
and being all covered by a longitudinal arch of fire-brick having suitable
working holes provided on both sides, a very steady heat is produced
affecting each pot in precisely the same manner, no matter how many
pots may be placed in one row. The sieges are inclined toward the
sides of the furnace where spilt glass is removed through foot holes;
the necessity for glass pockets is thereby obvialed and the construction
of the furnace is much improved as regards cost of erection and of
maintenance.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles William Siemens in the Great Seal Patent
Office on the 20th November 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WILLIAM SIEMENS, of No. 3, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of May, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Charles William Siemens, Her special
licence that I, the said Charles William Siemens, my executors, admi-
nistrators, and assigns, or such others as I, the said Charles William
Siemens, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter

page_text: during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN CALOINING AND SMELTING OBES, AND IN FURNACES AND Appa-
BATUS EMPLOYED IN CONNECTION THEREWITH, WHICH FURNACES ARE ALSO APPLICABLE
TO OTHER PURPOSES," upon the condition (amongst others) that I, the said
Charles William Siemens, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that 1, the said Charles William Siemens, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement thereof, reference being had to the accompanying
Drawings, and to the figures and letters marked thereon, that is to
say:
If iron or other metallic ores contain water of hydration, carbonic
acid, sulphur. or other volatile constituents, they are generally washed
or calcined in kilns or upon the bed of a long reverberatory furnace.
The calcining kiln has the advantage of greater simplicity, but is only
applicable to ore in pieces of such size that the flame can circulate
between them, whereas the caleining furnace has to be resorted to in
dealing with ores of small grain or of a friable nature. The latter process
has the advantage that no residual matter resulting from the combustion
of solid fuel is mixed with the ore, and that the temperature and time
of operation can be varied at will; but on the other hand it involves a
considerable amount of attention and manual labour in burning the ore.
To avoid this it has also already been proposed to calcine the ore in
rotating cylinders.
The first part of my Invention consists in effecting the calcination of
metallic ores, and also the burning of such substances as cement, lime,
or plaster of Paris, in a drum or cylinder of iron lined with hollow fire-
brick forming longitudinal channels which is mounted upon rollers and
is made to rotate round its horizontal axis. The ores or substances to be
burnt are introduced through a slanting hopper at one extremity of the

page_text: gas
rotating drum, and being worked gradually forward by the rotation
under the influence of heat they drop in a continuous manner from the
other open extremity into a stationary close receiver or chamber, whence
they can be removed at pleasure. A smoke box communicating with a
chimney is fitted to the extremity of the cylinder where the ores enter,
and a current of air is induced by the chimney to pass through an outer
jacket of the smoke box and through the longitudinal channels in the
lining of the drum itself to the ore receiving chamber, where it is met
while in a heated condition by a current or currents of combustible
which has by preference also been previously heated by passing through
a jacket surrounding the receiving chamber. The flame thus resulting
at or near the extremity of the exit of the rotating drum passes through
the same (heating the ore), and thence through the smoke box to the
chimney, being by that time thoroughly deprived of heat by the cold
incoining ore and the incoming air in the smoke box jacket. The com-
bustible gases employed may be derived from a blast furnace or from a
gas producer such as described in the Specifications to my former Letters
Patents, No. 167 of 1861, and No. 3018 of 1864; or liquid fuel or solid
fuel in form of powder may be employed, which is forced in by a jet of
steam or a current of air under pressure. If the volatile substance to be
removed from the ore or other substances is carbonic acid or moisture a
sufficient supply of gas must be admitted to raise its temperature near
the exit to the requisite degree, but the supply of gas may be very much
reduced, and may even be stopped entirely, if sulphur is emitted from
the ore in considerable quantity. The sulphurous acid produced in that
case may be condensed or utilized by passing the products of combustion
through a scrubber or through lead chambers on their way to the
chimney or to an exhausting apparatus, or a jet of water may be intro-
duced at the bottom of the smoke box for condensing the gases.
Figures 1, 2, and 3 on Sheet 1, of the accompanying Drawings show
one arrangement of my before described rotary calcining apparatus.
Figure shows a longitudinal section of the apparatus; Figure 2 shows
a transverse section on line 2, 2, Figure 1; and Figure 3 shows a trans-
verse section on line 3, 3, Figure 1. Similar letters of reference indicate
similar parts in each of the Figures.
The iron drum or cylinder A provided with a lining of fire-brick B is
supported upon rollers C; C, and caused to rotate at a slow speed by
means of an endless band or chain D (indicated by dotted lines in

page_text: Figure 2) passing round in the forked spokes E fixed to the cylinder and
driven by any convenient motive power; or the drum may be rotated
by any other suitable known contrivance. In the fire-brick lining B are
formed longitudinal channels or passages F, F, communicating at one end
with the jacket G to the smoke box H (from which jacket atmospheric air
is made to enter these passages), and at the other end with the interior of
the chamber I, the end surfaces of the rotating drum A being made to
abutt in a sufficiently air-tight manner against the said smoke box H and
chamber 1. The ore or other material to be calcined is introduced into
the drum through the shoot K, passing through the smoke box H and
the central opening in the plate A' into the interior of the drum, which
also communicates by means of the central opening in the plate A' with
the interior of the smoke box, as shown. By the rotation of the drum
the ore is caused to travel gradually along, the same being effectually
stirred up during its transit by means of the projections B' formed in the
fire-brick lining. The ore receiving chamber I has a jacket L. into which
combustible gas from a gas producer or blast furnace passes through the
opening M, and from which after taking up heat from the ore in the
chamber the gas issues through the perforated pipe N into the exit end
of the drum.
If pulverized or liquid fuel is employed in place of gas an arrangement
of the nature shown in Figure may be employed, where the fuel
is introduced in a continuous stream or in small quantities into the
receiver 1, whence it is blown by preference by a steam jet 2 so as to
issue in a divided condition through the pipe 3 into the end of the
rotating drum A, where it enters into combustion with the heated air
passing in through the passages F, as before described. Here the heated
gas or pulverized or liquid fuel meets with atmospheric air issuing from
the channels F (which air has also become considerably heated in
traversing such channels), and in entering into combustion therewith
produces the requisite heat within the drum for effecting the calcination
of the ore. The hot gaseous products of combustion in being drawn
along towards the charging end of the drum, owing to a current being
induced in the latter by means of a chimney or exhausting apparatus
communicating with the smoke box H, they are made to impart the
greater part of their heat to the incoming ore before escaping into the
smoke box, where a further portion of their heat is absorbed by the
incoming air passing in an upward direction through the jacket G towards

page_text: the passages F. Arrived at the bottom of the smoke box the cooled gases
are brought into contact with fine water spray issuing from the jet O in
the condensing chamber P, similar in arrangement to that described in
my Specification, No. 1892 of 1868, whereby any sulphurous or other
fumes contained therein are condensed, the purified gases passing from
the chamber P through the flue Q to the chimney, while the water
containing the condensed sulphurous acid and other fumes, &c., falls to
the bottom of the chamber P, whence it is caused to pass through a
filtering surface or grating R into the drain S, leaving any condensed
solid matter in the bottom of the chamber B, whence they are removed
from time to time. By extending the pipe N the combustible gas or its
substitute of liquid or solid fuel may be led forward any desired distance
into the rotating drum so as to cause the combustion to take place at a
point at some distance from the exit end of the drum in order to expose
the calcined ore finally to the chemical action of the uncombined oxygen
of the air passing in, and to impart additional heat to the air and gas
before entering into combustion. By the accumulative action thus set
up the maximum temperature within the rotating drum may be raised
even to a white heat. If the ore to be calcined contains sulphur or
phosphorus I mix the same with, say 10 per cent. of solid carbon, such as
coke or anthracite, in order to effect its partial reduction; at the same
time I direct a divided current of steam issuing from the perforated
pipe T in the chamber I through the mass of highly heated calcined ore
accumulating in the chamber, which steam being highly superheated
will be decomposed in contact with the heated reduced metal and carbon,
liberating nascent hydrogen, which will combine with the phosphorus
and sulphur, carrying off these objectionable admixtures of the ore.
ore after being subjected to this action is removed from the chamber
through the opening I. If the ores contain such foreign substances as
may be rendered volatile or soluble by the chemical reaction of another
substance under the influence of heat, such other substance may be
charged in with the ore in the requisite proportion. Thus, for instance,
if the iron ore under treatment contains copper, common salt may be
added, and the chloride of copper produced may be separated by levi-
gating the calcined ore, which may be made to fall througli a spout from
the revolving drum into a cistern filled with water, whence it is raised
by a Jacob's ladder to the platform or hopper of the smelting furnace,
being at the same time subjected to the action of a shower bath of fresh
water for removing therefrom all soluble matter, and the copper dis-
The

page_text: solved in the bath may be separated from time to time by well known
processos.
Figure 4 shows a longitudinal section of an arrangement such as
above described for levigating the calcined ore. The rotating calciner A
with smoke box H and ore receiving chamber I are constructed in a
similar manner to the arrangement shown at Figures 1 to 3. The
chamber I is open at its lower end and dips into the water contained in
the trough U, into which trough the calcined ore consequently falls,
and where it is separated from all soluble impurities. From this Trough
the ore is removed by means of the travelling Jacob's ladder V, which
carries it up to the point W where it is deposited, being subjected on its
way to the action of numerous jets of water falling from the cistern withi
perforated bottom X. The water in the trough U may be made to flow off
and be replaced by fresh water from time to time. In cases where the
calcined ores have not to be washed, but are intended to be smelted or
reduced into the metallic state, I prefer to place the calcining cylinder
above the smelting or reducing furnace in order to save the heat residing
in the calcined ore for the succeeding operation. Thus these calciners
may be placed in the top of a blast furnace or over the receiving hopper
of the ore reducing apparatus described in the Specification to my
Patent, No. 1892 of 1868, for the manufacture of cast steel from the ore.
If I want to produce pulverulent metallic iron I combine the calciner
above described witli the rotating ore reducing apparatus described in
my former Patent just alluded to, the reduced ore being made fo fall
into a closed metallic chamber which is cooled externally by currents of
water or gases, and which is provided with doors at the lower extremity
for the removal of the pulverulent iron after it has had time to cool
to prevent its taking fire when brought into contact with the atmo-
spheric air.
Figures 5 and 6 slow respectively a part longitudinal section and a
section on line 6, 6. Figure 5, of sucli an arrangement of the ore
reducing apparatus. The lower part of the chamber a into which the
pulverulent metallic iron falls from rotating drum b is constructed with
two separate iron receptacles a', a, surrounded by a water jacket c
through which cold water is made to circulate, entering at bottom
through the pipe and passing off at top through the pipe e. Thé
discharge apertures to the chamber's a¹ are kept closed by doors f until
the pulverulent iron has become sufficiently cooled by the circulation

page_text: of the water when the valve is opened and the iron is allowed to fall out
into a truck or other receptacle. The construction of the rotating
reducing drum b is the same as described in my before-mentioned
Specification, No. 1892 of 1868, and need therefore not be further
described.
The calcining apparatus before described is also particularly applicable
to zinc ores. These ores may be fixed with carbon and distilled in the
usual manner, but I prefer to employ inclined retorts opening at both
ends so as to admit of being charged and discharged in a continuous
manner. These retorts are arranged in double rows in a regenerative gas
furnace of a special construction resting with their inclined sides against
the central longitudinal wall in the middle of the furnace. Into this
wall passages rise from the four regenerators, such passages terminating
in orifices facing the two opposite working sides of the furnace, the gas
and air passages being arranged alternately. The heated air and gas in
issuing in parallel streams towards the working side, which is for the
time being the front of the furnace, and rising between the retorts enter
only gradually into combustion and diffuse a uniform and gentle heat
throughout the furnace. The gases turn over the middle wall towards
the back of the furnace, where after descending between the second row
of retorts they escape promiscuously through the second set of air and
gas passages and through the second pair of regenerators downward
towards the chimney. On reversing periodically the furnace valves the
direction of the flame through the furnace is also reversed. Instead of
using inclined retorts arranged for being charged in a continuous
manner one or more tiers of ordinary Silesian or Belgian retorts may be
so arranged in the furnace that the ends of the retorts farthest from the
two working sides may be supported upon the before-mentioned central
wall, through which the gases are introduced and withdrawn alternately.
The space below the retorts where the gases meet serve also to receive
pieces of broken retorts which can be readily removed from time to time
through doors in the front and back of the furnace.
Figures 7 to 9 on Sheet II. of the Drawings show tlie last described
arrangement of my improved zinc furnaces. Figure 7 shows a transverse
section of the furnace; Figure 8 shows a part side elevation, and
The furnace is
Figure 9 shows a part section on line 9, 9, Figure 7.
constructed with two working sides g, g, and a central
wall h, into the opposite sides of which rise the two sets of
longitudinal
passages
for

page_text: combustible gas i and for air from the regenerators j, j', such gas and
air passages being arranged alternately, as shown, and having apertures
facing towards the working sides of the furnace. The two opposite rows
of retorts le, k, of ordinary construction are arranged in several tiers
above each other and rest with their inner ends upon the wall h. The
combustible gas and air issuing from the passages i and i', say, on the
right-hand side of the wall are projected towards the working side of
the furnace and in entering into combustion rise up between the retorts k,
towards the roof of the furnace, where they pass over the top of the wall h
and then descend among the retorts on the other side of the wall, and
finally escape through the passages i, i, on the left-hand side into the
other pair of regenerators j, j'. On reversing the valves of the regenera-
tors this action of the furnace is also reversed. By this arrangement as
before stated a very uniform and gentle heat is diffused throughout the
furnaces. After completion of the process of distillation the contents of
the retorts are discharged through the openings into receptacles
below the ground. The spaces m on the bed of the furnace below the
retorts and gas and air apertures serve to receive any pieces of broken
retorts, &c., which are removed from time to time through apertures n
closed by plugs. Passages o, o, are formed in the middle wall h. of
the furnace, communicating with vertical passages o', communicating at
top with the atmosphere, whereby a current of air is induced in the
passages preventing the overheating of the wall.
Figures 10 to 14 shew two different modifications of the first described
arrangement of zinc furnace, namely, where the retorts are arranged so
as to be charged at the one end and discharged at the other end. In
the modification shewn in the transverse section, part side elevation, and
part longitudinal section respectively at Figures 10, 11, and 12, the
two opposite sets of retorts h, k, rest in inclined positions with their
upper open ends upon the middle wall of the furnace, while the
lower ends pass through the working sides g of the furnace where they
communicate at with the usual condensing chambers, and are pro-
vided with openings for discharging them in a continuous manner,
the ore being introduced into the upper ends of the retorts also in a
continuous manner from the hopper into which it is charged by
trucks running on rails q'. As in the previous arrangement the gas
and air pass into the one side of the furnace through passages i and i'
formed in the middle wall h, and entering into combustion pass througli
apertures formed in the middle wall to the other side of the furnace

page_text: where the products of combustion descend and escape through the other
passages i, i, into the regenerators j.
In the modification shown in transverse section and part elevation,
and part longitudinal section respectively at Figures 13 and 4, the
action of the furnace is the same as in the foregoing one, with the
exception that the retorts, instead of being continually charged
and discharged, are charged periodically, each charge being worked out
and discharged before more ore is introduced. The retorts are for
this purpose by preference arranged vertically as shown, (though they
may also be arranged in inclined positions as in the previous case,) and
are placed with the lower open ends over openings m in the bed m of
the furnace, which openings are closed at the under side by means of
flaps, r, fixed on spindles 7, provided with balance weights, for
keeping the flaps closed until it is desired to discharge the contents of
the retorts, when by raising the arms of the balance weights the flaps
are opened and the ore is caused to fall from the retorts into the spaces s
beneath the furnace. The upper open ends of the retorts pass through
the top of the furnace, and are there closed by means of removable
condensing chambers into which the zine vapors distilled from the
charge of the retorts rise through the aperture t¹. When the distil-
lation of the charge is completed, which is ascertained by means of the
small side apertures, the condensers are removed by means of the
handles t, the flaps are opened, the contents of the retorts discharged
and after again closing the flaps a fresh charge is introduced. The
retorts may either be of small diameter and arranged in two rows as
at k, l, or they may be made of double width in one direction as at k¹.
The arrangement of the furnace is otherwise the same as before des-
cribed and need therefore not be again referred to. The same arrange-
ment of furnace, having a middle wall into which two sets of alternating
gas and air passages rise with orifices facing the two working sides of
the furnace, is also applicable with great advantage to other purposes
such as heating gas retorts or heating the pots for melting glass. For
making gas the same arrangement of furnace may be employed as
described with reference to Figures 7 to 9 by substituting for the
retorts & ordinary gas retorts arranged in the usual manner.
Figure 15 shows a transverse section, and Figure 16 a sectional plan of
an arrangement of the furnace adapted for glass pots. The arrangement
of the furnace with gas and air passages i, i, rising into opposite sides

page_text: of the central wall. is identical with those before described. The glass
pols u,, are arranged in rows on sieges or on the sloping bed m of the
furnace on either side of the wall
holes in the roof of the furnace.
affecting each pot in precisely the
pots may be placed in one row.
towards the sides of the furnace
the foot holes w closed with plugs. The necessity for glass pockets is
thereby obviated and the construction of the furnace is much improved
as regards cost of erection and maintenance.
and are accessible through working
A very steady heat is thus produced
same manner no matter how many
The bed mor the sieges are inclined
where spilt glass is removed through
Having thus described the nature of my Invention, and in what
manner it is to be performed, I wish it to be understood that 1 do not
claim generally the construction of revolving cylindrical calcining
apparatus, as I am well aware that such an arrangement has been
before employed, but what I claim is,-
First. Caleining ores or other substances by introducing them into a
rotating cylinder having a fire-brick lining, containing longitudna!
channels through which atmospheric air is made to circulate in order to
become heated before entering into combustion with currents of gas or
other combustible substances within the rotating cylinder, substantially
as herein-before described.
Second. Effecting the total calcination of metallic ore by bringing the
heated and partially calcined ore finally into contact with heated atmo-
spheric air alone by advancing the point of combustion any desired
distance into the rotating drum.
Third. Constructing caleining apparatus arranged and combined as
herein-before described with reference to Figures 1 to 3 of the accom-
panying Drawings.
Fourth. Introducing pulverized or liquid fuel into the calcining drum
by means of a steam or air jet, substantially as described with reference
to Figure 1 of the Drawings..
Fifth. Combining with such aforesaid caleining apparatus a condensing
chamber arranged and operating substantially as described with reference
to Figure 1 of the Drawings.
Sixtli. Introducing jets of steam among the heated and partially
reduced ore in the receiving chamber of the aforesaid caleining apparatus
for the purposes set forth.

page_text: Seventh. Combining a calcining apparatus constructed as herein-before
described with an ore reducing or smelting apparatus for the production
of cast iron or steel, so that the heat residing in the calcined ore is
utilized in the secondary operation.
Eighth. Constructing the rotating ore reducing apparatus described in
my Specification, No. 1892 of 1868, with a closed receiving chamber
provided with a cold water jacket for cooling pulverulent wrought iron
produced therein, substantially as set forth.
Ninth. Constructing regenerative gas furnaces for heating retorts or
pots with a central wall rising above the bed of the furnace between two
opposite working sides thereof, into which central wall two opposite rows
of alternate gas and air passages rise from the regenerators, their
apertures being so arranged in opposite directions that the gas and air
are projected forward on entering into combustion and are made to rise
between the retorts or pots in the furnace and to pass over the top of
the central wall and after descending on the other side therewith between
a similar set of retorts or pots the gases escape through the other row
of gas and air passages leading to the regenerators, substantially as set
forth.
Tenth. Arranging sloping or vertical retorts for the distillation or
smelting of zinc ore (the ore being charged and discharged at opposite
extremities) in combination with regenerative gas furnaces constructed
as herein-before described.
In witness whereof, I, the said Charles William Siemens. have
hereunto set my hand and seal, this Twentieth day of November,
in the year of our Lord One thousand eight hundred and sixty-
Witness,
THO. TAYLOR,
20, Southampton Bldgs.,
Chancery Lane.
C. W. SIEMENS. (L.S.)