IMPROVEMENTS IN ORE-ROASTING FURNACES
Year: 1883

page_text: LETTERS PATENT to Henry Harris Lake of the firm of Haseltine Lake
:
"
& Co, Patent Agents, Southampton Buildings London for an Invention of
IMPROVEMENTS IN ORE-ROASTING FURNACES" communicated to him from
abroad by Thomas Walker and Jolin F. Carter; both of Philadelphia,
Pennsylvania; United States of America
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 17th August 1883.
HENRY HARRIS LAKE, of the firm of Haseltine Lake and Co, Patent Agents,
Southampton Buildings London "IMPROVEMENTS IN ORE-ROASTING FURNACES
[a communication to him from abroad by Thomas Walker and John F. Carter,
both of Philadelphia, Pennsylvania, United States of America]
.
This invention relates to ore-roasting furnaces and comprises the novel
construction and arrangement hereinafter described.
The object of the said invention is to automatically, continuously, rapidly, and
cheaply de-sulphurize, oxidize, and chloridize properly prepared ores, also to
generate sulphurous acid fumes from pyrites..
In carrying the said invention into practice I provide a shell or wall of the
furnace having a heating-space around the retorts, the said space extending from
the fire-place to the flue or stack. The cylindrical retorts are about horizontal and
extend from front to back of the furnace, the ends of the said retorts being built
into, and supported by, the front and rear wall of the furnace and projecting
through to the respective outer surfaces thereof. Within each retort is a hollow
shaft which passes through each end or head of the retort and is provided within
the retort with rake arms or vanes. These rakes are arranged in series and each
flat tooth is at an angle or partially turned. Each series of every two opposite
sets of teeth is so set that as they revolve, the teeth of one rake will strike the
spaces corresponding to those between the teeth of its opposite rake. In other
words the teeth of each two opposite rakes on each shaft break joint with the
teeth of the. other in their revolution. The slant or partial turn given to each
Price B1
•

page_text: tooth of the rakes corresponds upon each single shaft, so that the operation of
revolving the rakes throws the ore in one direction in each retort. Each section
of comb is composed of the teeth, and a comb bar or back, which latter terminates
in two rings.
These rings are secured to the said hollow shaft by means of circular clamps.
Each of these clamps is composed of two half sections secured around the hollow
shaft by means of ears and bolts cast upon the adjoining ends of each half-section,
upon cach of which are cast ears or lugs to which are bolted the rings of the
comb.
Small projections located upon the interior surface of each clamp set into
corresponding recesses in the hollow shafts, and prevent the clamps from turning
thereon. The hollow shaft in the first retort receives at one end a current of
water through a water supply pipe. This current flows through the shaft and
down through a second water pipe to the hollow shaft in the second retort; thence
through this hollow shaft to a third water pipe thence into and through the hollow
shaft in the third retort, and a fourth water pipe into the hollow shaft in the
fourth retort, thence to and out of the exit-pipe.
All of these pipes join the revolving hollow shafts by suitably packed water-
joints and each pipe has a bend or curve in it. This bend is intended to give or
yield to the vertical expansion and contraction of the furnace to avoid the straining
of the water pipes. Ore passages or openings are made in the front and back walls
of the furnace from one end of each retort to the one beneath it. These openings
are located at a sufficient distance from such ends to ensure the ore which is
dropping down coming in contact with the rakes in the retort to which it has
dropped.
The retorts terminate in the thick brick walls of the furnace and the interior
brick work or brick flooring, is so constructed as to partially enclose each retort
along its side, or lengthwise of the retort, the alternate ends of this vertical series
of brick floors being open, whereby heat passes upward in a zig-zag course from
the furnace fire and finally out of the stack or chimney.
Ench section of brick-work flooring terminates at one end at a short distance from
the end wall of the furnace, thus leaving an opening or heat-passage at that end
through which the heat ascends, the alternate floors terminate at opposite ends,
thus rendering the course of the ascending heat tortuous or zig-zag. Now, these
openings or passages would be long and narrow, if it were not for the fact that
recesses are provided at each side of the furnace opposite each of these openings
simply to enlarge the latter.
1 employ two vertical series of retorts, and a description of one series will
answer for both. The rakes in each series are driven by means of cog-wheels one.
of which is located upon the end of each hollow shaft where that end projects
through the furnace walls. These cog wheels are located on the hollow shafts
between the water-pipes and the furnace-wall. They receive motion from worm-
wheels gearing into them which are located upon vertical shafts, which.shafts are
in turn driven by suitable gear wheels and pulleys. Oil-boxes terminating in cogs
under the said wheels are secured around the said upright shafts at intervals and
envelope the worm-wheels. These boxes and troughs catch and hold the oil used
to lubricate the gear-wheels and worm-gearing.
To carry off the fumes from the retorts into two side dust chambers I provide
passages. As the fumes rise through the said passages, should any fine dust pass
out with the fumes it will be carried into the dust-chambers with the said fumes
in which chambers, as the air-currents are slow, the dust will settle and can then
be collected. Each passage is furnished with an ordinary damper which is turned
from the outside of the furnace walls by means of bars, which bars are attached to
the outer ends of rods upon which the dampers swing. At one end of each retort
I provide one or more air-entrance openings closed by weighted slide-doors so
devised that by pushing the, weight up on a curved rib which fits in a slot in the
weight, the latter will jam and hold the door closed, and by reversing the motion

page_text: of the weight the latter will be freed, opening the door in its descent, and its
weight will hold the slide-door open.
The retorts being subjected to heat will expand and contract. It therefore
becomes necessary to so set the hollow shafts revolving therein as to prevent the
rake-teeth from striking the sides of the retort. To accomplish this each end or
head of each retort is provided with an opening (through which the hollow shaft
passes) of greater diameter than the hollow shaft itself. A large plate encircles the
neck of the shaft immediately outside of the retort head, of such size that whether
the shaft is shifted laterally or vertically this plate will always cover the hole in
the head of the retort. In order to adjust the shaft to such a line as, will free the
revolving rakes, I mount each end of each shaft in a housing. Vertically
adjusting screws bear against the bearings to raise and lower the said shaft, and
lateral adjusting screws shift the pedestal sidewise which will move the shaft.
One adjusting screw passes through a slotted opening in a ledge to admit of lateral
movement with the housing, this movement or adjustment will be very slight.
On that end of the shaft carrying a gear-wheel the supporting housing is located
between the gear-wheel and the end of the retort. Upon the opposite end of the
shaft the housing is located between the joint of the water-pipe and the head of
the retort.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Patent Office on the 16th February
1884.
HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings London "IMPROVEMENTS IN ORE ROASTING FURNACES." :-
A communication to me from abroad by Thomas Walker and John F. Carter,
both of Philadelphia, Pennsylvania, United States of America
This invention relates to ore-roasting furnaces and has for its object to
automatically, continuously, rapidly, and cheaply desulphurize, oxidize, and
chloridize properly prepared ores, also to generate sulphurous-acid fumes from
pyritos.
The said invention comprises the novel arrangement of apparatus hereinafter
described
In the accompanying drawings
Figure 1, is a vertical longitudinal section on the line a a Figure 2 of apparatus
constructed according to this invention
- Figure 2 is a vertical cross-section showing the positions of the retorts, with the
dust-chambers and gas and air exit flues.
Figure 3, is a front view showing the arangement of pulleys, gear wheels and
shafting for revolving the rakes or vanes within the retorts, and the kinked or
bent water-pipes connecting the various hollow shafts which carry the rakes, and
for conveying water from shaft to shaft.
Figure. 4, is a view of the furnace, showing the zig zag direction of the heat-
currents or products of combustion from the furnace-fire around the retorts until
they reach the exit flue or stack.
Figuro. 5, is an end view of one of the retorts projecting through the wall,
showing the closing and adjustable covers over the air-admission openings in the
retort.
Figure. 6 is a longitudinal sectional view of one end of a rake-bearing hollow
shaft, showing the pipe for carrying water therefrom and the means for securing
the said pipe to the end of the said shaft.
Figure. 7, is a view of one of the rake or vane sections detached.
Figure. S is a view partly in section of a portion of one of the hollow
rake-bearing shafts, the ring or clamp which holds the rakes being shown in
cross-section.
Figure..0 is an end view of the bearing in which the journals of the hollow
shafts rest, which bearing is adjustable vertically and laterally.
Figure, 10 is a view of one of the clamps for securing the rakes to the hollow
shaft; and
Figuro. 11 is a plan partly in soction of the housing shown in Figure. 9, the end
cofen hollow shaft being shown therein having upon it a gear-wheel whereby it is
driven.
A indicates tho shell or wall of the furnace; A¹, the heating space around the
retorts B B', & the said space extending from the fire-place C to the flue or
stack C. The cylindrical retorts B B, &c., are about horizontal and extend from
front to back of the furnace, the ends of the said retorts being built into and
supported by the front and rear walls of the furnace, and projecting through to the
respective outer surfaces thereof.
Within each retort is a hollow shaft D, which passes through each end or outer
head of tlie retort, and is provided within the retort with tho rako arms or vanes D',

page_text: These rakes are arranged in series, as shown, and each flat tooth is at an angle, or
partially turned in the manner shown in the end views of these teeth in Figure 1.
Figure. 7 also shows it. It will be observed in Figure. 1 that each series of every
two opposite sets of teeth is so set that as they revolve, the teeth of one rake will
strike the spaces corresponding to those between the teeth of its opposite rake.
In other words, the teeth of each two opposite rakes on each shaft break joint with
the teeth of the other in their revolution. The slant or partial turn given to each
tooth of the rakes corresponds upon each single shaft, so that the operation of
revolving the rakes throws the ore in one direction in each retort.
5
Each section of comb is composed of the teeth and a comb bar or back, which
lätter terminates in two rings D D. (See Figure. 7)
These rings are secured to the hollow shaft by means of the circular clamps E.
Each of these clamps E is composed of two half-sections secured around the hollow
shaft by means of ears and bolts cast upon the adjoining ends of each half-section.
(See Figure. 10.) Upon each half section are cast ears or lugs E¹ E¹, to which are
bolted the rings D of the comb D'. (See Figures 1 and 10.)
Small projections F F, located upon the interior surface of each clamp E extend
into corresponding recesses in the hollow shafts, and prevent the clamps from
turning thereon. The hollow shaft in the retort B receives at one end a current of
water through a water-supply pipe G, (See Figures. 1 and 3.) This current flows
through the shaft and down through a water-pipe G¹ to the hollow shaft in the
retort B¹ thence through this hollow shaft to a water-pipe G¹¹ thence into and
through the hollow shaft in the retort B, the water-pipe G the hollow shaft in
the retort B to and out of the exit-pipe GIV.
All these pipes join the revolving hollow shafts (see enlarged view, Figure 6)
by suitably packed water-joints, and each pipe has a bend or curve in it, such as
is shown in Figure 3 at H, H. This bend is intended to give or yield to the
vertical expansion and contraction of the furnace to avoid the straining of the
water-pipes,
Ore passages or openings are made in the front. and back walls of the furnace
from one end of each retort to the one. beneath it. These openings are located at
a sufficient distance from such ends to ensure the ore which is dropping down
coming in contact with the rakes in the retort, to which it has dropped. (See
I, I, I, Figure 1) The opening 1111 is the ore-entrance opening below the
hopper J, and the opening IV is the opening whence, after being roasted the ore
passes out.
The retorts terminate in the thick brick walls of the furnace, and the interior
brick-work or brick flooring, K K K K, (See Figure 4.) is so constructed as to
partially enclose each retort B, B1, B1, B" along its side, or lengthwise of the
retort, the alternate ends of this vertical series of brick floors being open, whereby
heat passes upward from the furnace-fire in the direction of the arrows shown in
Figure 4, and finally out of the stack or chimney C¹.
Each section of brick-work flooring K, as shown in Figure 4, terminates at one
end at a short distance from the end wall of the furnace, thus leaving an
opening or leat-passage at that end, through which the heat ascends. The alternate
floors K terminate at opposite ends, (see Figure 4) thus rendering the course of
the ascending heat tortuous or zigzag. Now, these openings or passages would be
long and narrow, if it were not for the fact that recesses are made at each side of
the furnace opposite each of these openings simply to enlarge the latter (See
K', K¹, K¹ and K“, K", K", Figure 2). Those recesses marked K¹ are at one end
of the furnace, while those marked K are at the opposite end of the same.
It will be seen that two vertical series of retorts are employed and a description
of one series will answer for both. The rakes in each series are driven by means
of cog-wheels L, L, L, one of which is located upon the end of each hollow shaft,
where that end projects through the furnace-walls. (See Figures 1 and 3.) These
cog-wheels are located on the hollow shafts between the water-pipes G G₁, &c., and
the furnace-wall. They receive motion from worm-wheels gearing into them,

page_text: which are located upon the vertical shafts LL, (sce-Figure. 3,) which shafts L'L's
are in turn driven by suitable gear wheels and pulleys
Oil-boxes M. M, terminating in troughs under the said wheels L L, are secured
around the upright shafts L L at intervals, as shown and envelop the worm-
wheels. These boxes and troughs catch and hold the oil used to lubricate the gear
wheels and worm-gearing.
The system of carrying off the fumes from the retorts into two side dust-chambers
through the passages 0, 0, 0, 0, & is illustrated in Figure 2, each vertical
series of retorts being furnished with a side dust-chamber, N or N. As the fumes
rise through the said passages 0 0, &, should any fine dust pass out with the
fumes, it will be carried into the dust-chambers with said fumes, in which chambers,
as the air-currents are slow, the dust will settle, and can then be collected. Each
passage 00', &., is furnished with an ordinary damper P, which is turned from
the outside of the furnace-walls by means of the bars P₁ P', which bars are attached
to the outer ends of the rods upon which the dampers swing. At one end of cach
retort I provide one or more air-entrance openings, QQ, closed by weighted slide-
doors QQ, so devised that, by pushing the weight up on a curved rib which fits
in a slot in the weight, the latter will jam and hold the door closed and by reversing
the motion of the weight the latter will be freed, opening the door in its descent;
its weight will hold the slide door open (Seo. Figure 5).
The retorts, being subjected to heat, will expand and contract. It therefore
becomes necessary to so set the hollow shafts revolving therein as to provent tho
rake-teeth from striking the sides of the retort. To accomplish this, each end or
head of each retort is provided with an opening, (through which the hollow shaft
passes) of greater diameter than the hollow shaft itself. A large plate encircles
the neck of the shaft, immediately outside of the retort-head, of such size that,
whether the shaft is shifted laterally or vertically, this plate will always cover the
hole in the head of the retort. In order to adjust the shaft to such a line as will
free the revolving rakes I mount each end of each shaft in a housing, or leaving
such as is shown in Figure. 9,. In this figure, D indicates the end of the hollow
shaft and R, R¹ vertically adjusting screws bearing against the bearings S S¹,
respectively to raise and lower the shaft. R" R" indicate lateral adjusting screws
to shift the pedestal sidewise which will move the shaft. The screw R¹ passes
through a slotted opening in the ledge T, to admit of lateral movement with the
housing. This movement or adjustment will be very slight. On that end of the
shaft carrying the cog-wheel L the supporting-housing is located between the gear
wheel and the end of the retort, as shown in Figure 11. This is not shown in
Figure 1, on account of lack of space. Upon the opposite end of the shaft, the
housing is located between the joint of the water-pipe and the head of the rotort.
The operation of the apparatus is as follows:-Fire is built in the furnace C, and
the products of combustion pass under, between, and over each tier of retorts,
through the flues at alternate ends of each tier of retorts, in a zigzag course,
through the heat-space A', in the manner indicated by the arrows in Figure 4, aud,
after being utilized, they pass out through the stack or chimney C, the damper in
which has been opened. The ore, after boing properly prepared, is fed into the top
retort B (see Figure 1.) from the hopper above, through the ore-feed pipe 11. At
the same time the rakes are started by revolving the shafts, to which they are
attached by the means described, and a cooling-current of water is either pumped
or allowed to run by gravity through the series of water-pipes and hollow shafts,
thereby preventing the shafts revolving in the retorts from bending or sagging by
reason of the heat. The feed of ore through the pipe I¹¹ is continuous and the
quantity of ore so fed into retort B is controlled at pleasure.
The motion of the rakes stirs up and thinly spreads the mass of ore, and brings
all the particles thereof into contact with the hot air in the rotort and the heated
walls of the same, theroby presenting a large and ever-changing surface of ore to
the action of the heat and air, the stirring of the ore boing thorough and
regular,

page_text: The "set" of the rake-teeth is such as gradually to drive the roasting ore toward
the opening I. Upon reaching this opening it drops in a continuous stream into
retort B¹. Here the operation of stirring and roasting continues, as before and the
rake-teeth of, this retort drive the ore toward opening.I', where it drops into
retort B, whence it continues in a similar manner through the other retorts and
passages, being roasted and stirred until its final exit through the passage I". The
operation is thus continuous and automatic.
The ore is fed through the pipe I in such quantity as not to choke up or fill
any one or more of the retorts, whereby the action of the rakes spreads the mass
of ore at the same time that the latter is stirred, and every particle of ore is
subjected to the action of the heat. Each end of each retort is furnished with
air-openings QQ. As it is necessary to. introduce air into the retorts to promote
the desulphurizing of the ore and the base metals therein, the air-passage in the
discharge end of retort B11 is opened and the fume-passage from the uppermost
retort into the dust-chamber is opened near the receiving end of the upper retort.
A draught is thus created from the said air-opening up through the series of retorts
into the dust-chamber, and the current of air will travel in the line or course of
this draught against and through the moving mass of ore being treated. Both
air-openings in the retort B, at the end referred to, can be opened if more air
is needed or, if still more air is desired, some of the air-passages in the other retorts
can be opened. If it is found that the ore, say, in the upper retort is being too
rapidly heated and is liable to fuse or mat, the passage from that retort to the
dust chamber can be closed and the corresponding passage in the next lower
retort opened which will result in carrying the air and fumes off before the
latter reach the top retort, thereby reducing the heat in the latter and preventing
the matting of the ore therein.
In case it is desired to reverse the direction of the air-current throughout the
whole series of retorts and carry it from top to bottom, the openings and passages
last described are closed, and the air-openings QQ at the receiving end of retort B
are opened, and the passage leading from the retort B to the dust-chamber from
the delivery end of retort B11 is opened. The air, in this case, will traverse from
top to bottom throughout the whole series of retorts. The air will always traverse
the retorts from any open air-passage to the point where there is an open fume-
passage into the dust-chamber. Both ends of each lower retort may be furnished
with passages into the dust chamber.
As will be seen by Figure. 2, it would appear that the retorts B¹ and B¹¹¹ only,
of each series, are furnished with fume-passages to the dust chambers; but, in fact,
the retorts B and B¹¹ of each series are also so provided; but the fume-passages of
the latter are near the rear of the furnace, and not shown in the view referred to,
which shows only the fume-passages which are set near the front of the furnace-
to wit, the fume-passages of retorts B and B are near the rear of the furnace,
while those of retorts B and B are near the front. The retorts B11 are furnished
with fume-passages into the neighbouring dust-chambers near both the front and
rear ends.
The horizontal arched walls in the two dust-chambers N N' (shown
in Figure 2) are narrow structures simply intended to give strength to the side
walls of the furnace.
Heretofore in roasting ores the ore has been carried through the series of retorts
in a thick mass occupying most of the interior of each retort, and for thorough
roasting, reliance has been placed upon the constant changing of the position of the
particles and bringing them in contact with the walls of the retort, as well as the
heated air passing through the same. This does not always result in a thorough
roasting, as it is difficult to reach all the particles. One of the features of this
invention is to remove this difficulty which is accomplished by carrying the ores
through the retorts in a thin layer, which is kept constantly disturbed by means of
the revolving vanes or stirrers, and subjecting it to heat while in such state. The
ore may be so treated in other apparatus than that herein before described.

page_text: Having thus fully described the said invention as communicated to me by my
foreign correspondents and the manner of performing the same I wish it understood
that I claim in a furnace for roasting ore.
First. The combination of the ore feed pipe 1, the retorts B, B', B¹¹, B¹¹¹, the
vanes or rakes D', D', D' for spreading the ore in a thin sheet, the passages 1, 11, 111
for carrying the ore from one retort to another, the discharge passage IV the dust
chamber N, the air-opening Q, a fume-passage O" into the dust chauber N in the
ore-discharge end of the lower retort B, and a fume passage and an air-opening
from the ore-receiving end of the upper retort B into a contiguous dust-chamber N,
whereby the draught can be directed from the lower retort through the series to
the upper or vice versa, substantially as described
Second. A series of retorts B, B¹, B", B connected one with the other by
suitable ore-passages I, 11, I", the said retorta being provided at one or both ends
with air-passages Q having suitable regulating-covers, Q, and also near one or
both ends with fume conduits or passages O, Ŏ into a dust-chamber N, the said
fumo passages being capable of being closed or opened by dampers or valves P,
whereby by the opening of any fume-passage O, when an air-passage Q has been
opened, a draught will be induced from the air passage to the fume-passage
substantially as described
Third A series of rotorts B, B, B", B" connected one with the other by suitable
ore-passages I, I, I", the fume-passages 0 0¹ & located at the ends of the
successive retorts in each series and connecting the interiors of the retorts with a
suitable dust-chamber N, and provided with suitable mechanism P to regulate the
draught or close the fume-passages, substantially as described.
Fourth A double vertical series of retorts B, B, B", B, the retorte in each
series being connected one with the other by suitable ore-passages I, II, II, and
dust-chambers N N'each adjoining one of the said two series of retorts and being
connected thereto by fume-passages 0, 0, 0, 0, substantially as described.
Fifth. The combination of a retort B, a centrally-revolving longitudinal shaft D,
rakes D' mounted in a series of longitudinal sections rigidly upon the said shaft by
means of the sectional rings E E, the sections of each of the said rings being
joined by ears and bolts, and the bases of the rake-sections being secured to lugs
projecting from the said rings by means of bolt-screws or rivets, substantially as
described.
In witness whereof I the said Henry Harris Lake have hereunto set my hand
and seal this sixteenth day of February in the year of our Lord one thousand
eight hundred and eiglity four.