Improvements in and relating to Ore Roasting Furnaces.
Year: 1892

page_text: Date of Application, 27th Dec., 1892-Accepted, 28th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in and relating to Ore Roasting Furnaces.
I, RICHARD PEARCE, a subject of the Queen of Great Britain, residing at
No. 1712 Sherman Avenue, in the City of Denver, County of Arapahoe and State
of Colorado, one of the United States of America, Metallurgist, do hereby declare
the nature of this invention, and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
The object of this invention is to provide a furnace for desulphurizing and
chloridizing ores and mattes, in which the mass of the material is constantly stirred
and also progressively moved from the inlet to the outlet.
In carrying out my invention, I make use of a turret-like annular furnace,
having one or more continuous annular hearths, and a series of arms radiating
from a common centre and carried around so as to sweep the hearth or hearths
from inlet to outlet, to move the ore continuously and progressively. These arms
are provided with a series of rabbles to stir the ore while it is in motion, and they
are made hollow, and supplied with cool air to reduce their liability of burning out,
the air being supplied also to the rabbles for a like purpose, and escaping into the
furnace and being heated to supply oxygen for calcination.
Having thus stated the principle of my invention, I will proceed now to describe
the best mode in which I have contemplated applying that principle, and then will
particularly point out and distinctly claim the part or improvement which I claim
as my invention.
In the accompanying drawings, illustrating my invention, in the several figures
of which like parts are similarly designated.
Figure 1 is a partly sectional plan view of portion of the furnace.
Figure 2 is a vertical cross section.
Figure 3 is a partly sectional plan view of the entire furnace.
Figure 4 is a vertical section, on a larger scale, of the centre column and the
rotating head carrying the radiating arms.
Figures 5 and 6 are respectively a cross section and an elevation of one of the
arms and rabbles and air feeders, and showing the air-feeders partly in section.
Figure 7 is a transverse section at the mouth of the furnace, and
Figure 8 is a longitudinal section through the discharge-slot of the furnace.
Figure 9 is a plan view, and Figure 10 a sectional elevation illustrating the
slot-guard.
Figure 11 is a sectional elevation of the left hand side of a double or two-
hearth furnace.
Figure 12 is a front view showing details of the door, and Figure 13 is a top
view of the same, both views partly in section.
The furnace is composed of an outer annular wall, a, built up of red brick or
other suitable material and a corresponding inner concentric wall, b, of like
material; and between these walls there is a frilling, c, of suitable material upon
which is laid the hearth, d, and this hearth is composed of fire brick or other
refractory substance. e, is the arch or crown of the furnace sprung from skew-
backs, a, and b, on the outer and inner walls respectively. The outer wall is
provided with wrought iron or other bands a³ and a, to resist the thrust,
respectively of the hearth and arch. The inner wall, b, is made with a continuous
slot or opening f, just above the hearth; and the lower edge of this slot is
protected by angle-irons g, while the upper edge, constituted of the skew-backs is
suspended upon angle-irons h, which in turn are suspended by U-bolts i, which are
supported by I-beams j, and these I-beams rest, at their outer ends, upon shoes k,

page_text: mounted upon the outer wall a, and are supported at their inner ends upon brackets 1,
which are mounted upon a central hollow column, m. Obviously, the I-beams j,
may be arranged otherwise than as just described and as shown in the drawings, in
order to accomplish the purposes for which they are intended, but as shown, the
said I-beams not only serve to support the skew-backs of the inner wall but they
also serve to stay the hollow column, m, from which, as shown, they radiate. The
skew-backs and the hollow column may be further braced and supported by means
of struts n, made fast to the angle-irons h, and the hollow column, and radiating
from the said hollow column. Fire-places o, of suitable number and disposition
are connected with the furnace, and the gases and other products of combustion
are carried off through an opening o² in the crown, as shown in dotted lines
Figure 3, to a dust-chamber o³, and thence to the stack o'. The ore to be treated
is fed into the furnace in any suitable manner through an opening p, (Figure 3)
in the crown, and the roasted ore is discharged from the hearth through an
opening in said hearth at the mouth 9 of the furnace. This mouth of the
furnace is adapted to receive a car, corve or hutch q³ for removing the roasted
ore, which car may be run into and out of the mouth underneath the discharge
opening 9 on rails provided for that purpose. On each side of the mouth of the
hearth a transverse door or guard r is provided, which is adapted to swing freely
in the direction of motion of the stirrer arms, hereinafter referred to, and to close
automatically after said arms have passed, so as to prevent the undue loss of heat-
see details in Figures 3, 7, 12 and 13. The door is shown as hung in bearings rl,
and, suitably supported in the masonry. The invention, however, is not limited
to these details. In case one of the I-beams j should be arranged over the mouth q³
its.end may be supported upon a bar or beam 2 which spans the said mouth and is
supported upon shoes on opposite sides of said mouth, as shown in Figures 7
and 8.
By constructing the furnace in the annular turret-like form, I obtain a maximum
length of furnace and a maximum exposure of the ore to be roasted in a minimum
of space.
The stirrers before referred to are composed of hollow arms s, which radiate
from a common hub s, which encircles the hollow column m. The outer ends s³,
of these arms are made detachable from the inner ends and are connected there-
with by couplings s', which couplings are arranged outside the inner wall b. The
ends of the arms are provided with rabbles t, rigidly suspended therefrom, at
about an angle of eighty (80) degrees with the axes of the said arms, and a
sufficient number of these rabbles is attached to each arm to extend practically
across the width of the hearth so as to cover the whole transverse area of the
hearth. The hub is made hollow and opposite the said hub the hollow column m
is provided with openings m². In connection with the said hollow column is an air
forcing apparatus (not shown) by which air, under pressure of one or more ounces,
may be supplied to the said column. The sections 83, of the arms are provided
with outlets for the air, and by preference these outlets are made as tubes u, which
extend downwardly behind the rabbles so as to supply air to them, whence it
escapes into the furnace and serves for oxidizing purposes in the process of calcina-
tion. In order to close the space between the hollow column and the hollow hubs',
any suitable flexible covering may be employed, and I have shown bands of
canvas v, made fast to the column by metal bands and having their outer ends
provided with metal bands v³, resting upon the hub and held there in any suitable
manner, as by springs vt, which springs may be fastened to the bands ; but I do
not limit my invention to any particular means for closing the space between the
hollow column and the hub. The details of the connection of the hollow column
and the hollow hub are shown more particularly in Figure 4. As will be under-
stood from the foregoing, the arms's project into the hearth through the slot f,
and as will be understood also the outer ends of these arms are exposed to the
highest temperature and consequently the greatest wear; hence by making the
said outer ends detachable from the arms, they and the rabbles may. be readily

page_text: renewed as they are burned or worn out, without the necessity of disassembling
the whole length of arms.
In order to close the slot against the escape of the heat and products of com-
bustion, I provide a sectional shield w, which is suspended from brackets to³ on the
couplings, and through which shield the arms s project into the furnace. This
shield is curved to correspond to the curvature of the inner wall and is pressed up
against the adjacent edges of the slot by any suitable means, as for instance,
weighted bell crank levers w-see Figures 9 and 10. Of course this shield is
carried around by the rotation of the arms.
The circular track y is supported in any suitable manner, as upon girders y
borne by the inner wall and the hollow column. The couplings stare provided
with wheels or rollers y³ which move upon said track and support the arms upon
such track. The arms are provided with a suspended toothed-ring z and this ring
is guided and braced on the inside by guide rollers, which may be mounted upon
the supports y of the track y. A pinion 2 is mounted upon a shaft 3 and engages
the toothed ring 7, and this shaft 3, is connected by gearing 4 with a power
shaft 5.
Obviously, by the rotation of the pinion 2, the arms 8, will be rotated about
the column m, and the rabbles will be caused to traverse the hearth in its entire
circumference, taking in their course the ore from the inlet and progressively
moving it and continuously stirring it from that point to the point of discharge.
As shown in Figure 11, my improved furnace may be constructed in one or
more stories, that is to say, the hearths may be arranged in tiers, or one above the
other; and in such case the upper hearth will, by preference, be supported above
the I-beams j, upon foundation plates 6, and arches 7. In order to transmit power
to the arms of the upper furnace, the lower furnace may have its toothed ring
duplicated at 8, on the upper side of the arms, and this toothed ring 8 will be
engaged by a pinion 9 on a shaft 10, which carries the pinion 2 of the upper
furnace. The upper hearth may be entirely independent of the lower hearth, but
usually there will be communication between them, so that the heat and products
of combustion may pass from the lower to the upper, and the roasted ore from the
upper may pass to the lower. If it be desired to drive the arms of the upper
hearth in the direction the reverse of that in which the arms of the lower hearth
are driven, then one or the other of the toothed rings will be made larger and have
its teeth on the inside instead of the outside. It is apparent that with the same
method of construction and the same transmission of power, any number of hearths
may be built one above the other. Those parts of the double furnace corresponding
with the single furnace as heretofore described, are designated by the same reference
characters.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. An annular or turret-like furnace for roasting ores, consisting essentially of
an outer wall and an inner wall with a hearth between them and a suitable arch or
crown, the inner wall having a continuous horizontal slot arranged above the
hearth, combined with stirrer arms extending into the furnace through the slot and
provided with rabbles, and means to rotate the stirrer arms to cause them and their
rabbles to traverse the furnace from inlet to outlet and thereby progressively move
and constantly agitate the ore, substantially as described.
2. An annular or turret-like furnace for roasting ores, consisting essentially of an
outer wall and an inner wall with a hearth between them and a suitable arch or
crown, the inner wall having a continuous horizontal slot arranged above the
hearth, combined with stirrer arms extending into the furnace through the slot and
provided with rabbles, a shield arranged upon the arms to cover the slot, and means
to rotate the stirrer arms, as and for the purpose described.
3. An annular or turret-like furnace for roasting ores, consisting essentially of an

page_text: outer wall and an inner wall with a hearth between them and a suitable arch or
crown, the inner wall having a continuous horizontal slot arranged above the
hearth, combined with stirrer arms extending into the furnace through the slot and
provided with rabbles, and means to rotate the stirrer arms to cause them and their
rabbles to traverse the furnace from inlet to outlet and thereby progressively move
and constantly agitate the ore, and means to supply air to the stirrer arms and their
rabbles and thence to the furnace, substantially as described.
4. An annular ore roasting furnace made in one or more tiers, each comprising
outer and inner walls, a hearth between these walls, and a crown or arch
over them, the inner wall having a continuous horizontal slot above the hearth,
the upper edge of which slot is constituted of skew-backs for the crown or
arch, angle-bars in which said skew-backs are supported, transverse I-beams and
supports therefor, and bolts suspending said angle-bars from said I-beams, com-
bined with stirrer-arms projecting into said furnace through said slot, and means to
move said arms to cause them to traverse the furnace from inlet to outlet, as and
for the purpose set forth.
Dated this 27th day of December 1892.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.