Improved Apparatus for Roasting Pulverized Ore and other Substances.
Year: 1895

page_text: Date of Application, 7th Feb., 1895
Complete Specification Left, 9th Dec., 1895-Accepted, 7th Mar., 1896
PROVISIONAL SPECIFICATION.
Improved Apparatus for Roasting Pulverized Ore and other
Substances.
I, PAUL NAEF, of 453 Ruby Avenue, Argentine, Kansas, U.S.A., Doctor of
Philosophy, do hereby declare the nature of this invention to be as follows :-
:-
The object of this invention is to provide an apparatus for roasting pulverized
ore and other substances, and which will afford a most intimate contact between the
ore and the air admitted for the combustion of the sulphur contained in the ore.
The invention comprises a rotatable cylinder supported in an inclined position
upon rollers, and caused to revolve by a worm-wheel encircling it and a worm upon
a driving shaft. One end of the cylinder abuts an opening in a chimney or flue
which carries off the gases. The interior of the cylinder is thickly lined with
fire-brick or similar material or substance to prevent loss of heat and contact with
the metal cylinder of the ore. The outlet end of the cylinder is closed by a cap
or end-plate which has a central aperture, through which projects a tube into the.
interior of the cylinder. This tube is surrounded by a larger tube extending
nearly the length of the cylinder and having apertures through it to permit air
entering from the central tube to escape into the cylinder.
Any suitable number of partitions divide the cylinder longitudinally into a
number of chambers and, each partition has apertures through it so that the ore
can pass from one chamber to the other as the cylinder revolves. These partitions
and chambers do not however extend the whole length of the cylinder, inasmuch
as a part thereof nearest the flue, has agitators or projections upon its inner
surface to constantly raise and let fall the ore before it enters the chambers
aforementioned. A chute enters this part of the cylinder to permit the introduction
therein of the ore. The moisture, which is injurious to the metal partitions,-is
evaporated in this part of the cylinder before entering the remaining portion
thereof. Suitable valves are fitted in the outlet end of the cylinder and are opened
successively by a cam as they are brought round by the rotation of the cylinder,
to permit the exit of a portion of the roasted ore.
Dated this 7th day of February 1895.
Improved Apparatus for Roasting Pulverized Ore and other
Substances.
I, PAUL NAEF, of 453 Ruby Avenue, Argentine, Kansas, U.S.A., Doctor of
Philosophy, 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 invention relates particularly to the class of revolving cylindrical roasters
in which the pulverized ore or other material to be roasted or calcined is fed into

page_text: an inclined cylinder at one end and discharged at the other, the ore passing into
and out of the roasting cylinder in a continuous stream, and the object of the
present invention is to provide such a furnace which will afford a most intimate
contact between the pulverent ore and the air admitted for the combustion of the
sulphur, carried by the ores, and will produce as a product, a perfectly roasted ore,
and also concentrated sulphurous acid gas, by reason of the manner in which the air
requisite for the combustion is admitted to the roasting cylinder.
A further object in view is to reduce the first cost of such a furnace and the cost
of repair by a system of iron partitions, and an arrangement of the air inlet ducts
and furnace construction which prevents the destruction of the iron used, from too
high a heat, or the action thereon of sulphuric acid generated in the furnace.
These objects I attain by means of the construction and arrangement hereinafter
described and claimed.
In the accompanying drawings:
Figure 1 is a vertically longitudinal section of a revolving roasting furnace
embodying the present invention. Fig. 2 is an end view of the discharge end of
the same.
Fig. 3 is a transverse section taken on the line x-x of Fig. 1.
Fig. 4 is a transverse section taken on the line
y-y, Fig. 1; and
Figs. 5 and 6 are transverse sections of a roasting cylinder illustrating
modifications in the construction of the partitions.
The roasting cylinder A is constructed of an iron shell A', lined throughout
with fire brick B. It is supported on rollers M, M₁, as many as requisite, the
cylinders being generally about thirty feet in length, and driven by a worm
pinion N, engaging with a rack circle n carried by the cylinder, or otherwise. The
hearing rings for the rollers M and M' are shown at m and m' respectively. The
fire brick lining to the furnace is, with advantage, made of considerable thickness
so as to retain heat and equalize the roasting. On the inside of the brick lining of
the cylinder and extending longitudinally therewith, there are the angle irons a,
attached to the outer iron shell A' by bolts b which pass through holes in the fire
brick lining B. To these angle irons there are bolted or riveted the radial iron
partition plates C. C, which plates, in the first form of construction illustrated, are
bolted or riveted, along their inner edges, to angle irons or flanges attached to or
formed on the central iron tube D.
Each of the plates C is provided with a line of holes, c, and as the cylinder
revolves the partitions successively lift the ore and allow it to fall in a shower
through the holes c, from one of the radial chambers formed by the partitions, into
the next chamber. Thus a shower of ore is produced over the whole cross section
of the cylinder.
The discharge end of the roasting cylinder is closed by a plate d, which plate
also closes in the end of the iron tube D, and the opposite end of the tube D is
closed by a head plate d'. Through the centre of the plate & there is inserted a
smaller pipe E, an air inlet, which pipe extends in nearly, to the farther end of the
encompassing pipe D, and is supported and stayed to the latter by the bolts e'.
Openings e are provided in the pipe D near the discharge end of the cylinder, for
the passage of air from the central pipe into the roasting cylinder as hereinafter
described.
In most cases it is not desirable to allow iron constructions to come in contact
with the ore during the first stage of roasting, for the heat at that point is the
greatest, and further, if the moisture is all driven off from the fresh ore before it
reaches the iron parts of the roaster, the destruction of the latter by sulphuric
acid is avoided. To this end the iron partitions, C, and the central tube D do not
extend entirely through to the receiving end of the roasting cylinder, but stop
short as shown, and the brick lining of the upper end of the cylinder is provided
with longitudinally projecting ledges H which form ore lifters that carry up the
ore as the cylinder slowly revolves, and allow it to fall back in showers.
The upper end of the cylinder fits closely against the face of the stationary

page_text: flue P, which may lead to a chimney stack or to appliances for treating or saving
the sulphurous or other gases produced by the roasting process. A feed chute for
the ore is shown at R and the ore is fed into the cylinder in a steady stream, by
any suitable automatic feeding device in the usual way. In the present case a feed
hopper and chute simply are shown, it not being necessary to illustrate the details
of an automatic feeder.
The successful operation of the roasting furnace requires the exclusion of all air
except such as enters through the air inlet pipe E, and becomes warm before it
reaches the ore, and also calls for a uniform and automatic discharge of the roasted
ore. For this purpose there are discharge openings f, in the discharge end d, of
These
the cylinder, one opcuing for each longitudinal section or apartment.
openings are normally closed by means of the spring pressed doors or covers g,
each of which is hinged to a supporting arm g', and has an outwardly extending
arm i.
is the spring for holding the door against its seat.
G is a stationary rod or cam surface conforming in curvature to the diameter of
the cylinder as will appear from. Fig. 2, and so placed with respect to the end of the
roasting cylinder that it will engage with the rods i and press them back, opening
the discharge holes as they successively approach the bottom position, and old
them open for a short period. After each rod i has passed the stationary cam rod G
the cover closes down on its opening till the furnace has again made a revolution
and the opening remains closed against the admission of cold air. In connection
with each opening there is a slide K which can be pushed in more or less in order
to reduce the size of the opening f. The openings when fully open extend to the
inner edge of the cylinder lining, and by pushing in the slide K it will be seen that
a barrier is formed against the free discharge of all ore resting at that point on the
bottom of the cylinder. Only such ore as can flow over the inwardly projecting
end of the slide plate K can be discharged. Hence the amount of ore in the
furnace can thus be regulated at will according to the character of the ore, which
is a great advantage in securing good roasting.
It will be seen that it is not material how many of the iron partitions the furnace
has. Instead of four as above described there may be five as illustrated by Fig. 5, and
in this case there would be six discharge openings. In Fig. 6 each of the partition
plates C is bent laterally and riveted along its inner edge to the adjacent plate
thus enclosing a central space which performs the function of the tube D in the
first construction.
The operation of the furnace is briefly as follows: The ore being fed in steadily
and continuously through the feed spout R it enters the upper end of the cylinder
and as the latter slowly revolves it is carried up by the ledges H, and later by the
partitions C, and showered through the openings c, thus giving an intimate and oft
repeated contact between the ore particles and the hot air. Finally when the ore
reaches the lower end of the cylinder it discharges through the openings, the
same being automatically opened for a short period of time, as before described,
when they reach the lower part of the cylinder's revolution, and then closed for
the rest of the circle. The air enters only through the centre pipe E and natural
draft alone may be used or it may be forced in by means of a fan or blower.
Passing in to the farther end of the pipe E it then returns through the annular
passage around the pipe E and within the pipe D, or in the case of the construction
illustrated by Fig. 6, through the tight central chamber around the pipe E. The
air then enters the roasting part of the furnace through the holes e. During the
passage of the air along the red hot iron it is heated, and the iron, especially at
the inner end of the flue D where the heat from the roasting of the fresh ore is the
greatest, is cooled and preserved from destruction. A part of the superfluous beat,
which produced by the intense combustion of fresh ore near the feeding end of
the furnace, is thus transported to the discharging end, where in ordinary furnaces
a large volume of cold air meets partially burned ore and reduces the heat below
the roasting temperature. If ore is to be roasted which does not furnish enough

page_text: heat by its own combustion, the air can be heated before it is introduced through
the pipe E.
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) A revolving roasting furnace having a central metal air inlet pipe receiving
air in at one end and with openings therefrom into the roasting cylinder only at the
discharge end thereof, in combination with metal partitions connecting said central
pipe with the cylinder walls, said partitions having holes for the passage of ore
therethrough substantially as and for the purpose set forth.
(2) In a revolving roasting cylinder the combination with an inner air inlet pipe
leading in from the discharging end of the furnace towards the feeding end, of an
outer pipe encompassing the same and forming a return passage for the incoming
air back to the discharging end of the cylinder, substantially as and for the purpose
set forth.
(3) A revolving roasting cylinder having an open section at the feeding end
with lining and ore lifting devices carried thereby of fire brick, in combination
with a metal air inlet pipe, and ore lifting partitions extending through the lower
portion of the cylinder, said air inlet pipe discharging air into the roasting
chamber near the discharging end thereof, substantially as and for the purpose set
forth.
(4) A revolving roasting cylinder having one or more discharge openings in the
end wall thereof with spring pressed doors therefor each hinged to the cylinder
between the opening and the cylinder axis and having a radially and outwardly
projecting arm therefor in combination with a stationary piece so placed as to
engage with said arms and temporarily open the doors substantially as and for the
purpose set forth.
(5) A revolving roasting cylinder having an open section at the feeding end with
lining and ore lifting devices of firebrick, in combination with an air inlet flue and
metal ore lifting devices extending through the lower portion of the cylinder, said
air inlet flue discharging air into the roasting chamber near the discharge end
thereof substantially as and for the purpose set forth.
(6) A revolving roasting cylinder having one or more discharge openings in the
end thereof, said openings extending inward from the surface of the furnace lining,
with movable slides therefor adapted to be moved radially inward, whereby the
amount of ore retained the cylinder can be regulated, substantially as set forth.
Dated this 7th day of December 1895.