Improvements in and relating to Pneumatic Separators.
Year: 1897

page_text: Date of Application, 6th Apr., 1897-Accepted, 22nd May, 1897
COMPLETE SPECIFICATION.
Improvements in and relating to Pneumatic Separators.
We, GEORGE RAYMOND and ALBERT RAYMOND, both of 1402 Monadnock
Block, in the City of Chicago, County of Cook and State of Illinois, United
States of America, Manufacturers, 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 :--
This invention has relation to a separator in which the material to be separated
is carried by a moving air current an 1 the separation is effected by gravity; and
the invention is particularly adapted for use in connection with the treatment of
materials wherein the finished product, or oue grade thereof, is in the form of an
impalpable powder.
We have shown our invention in one forin embodied in an apparatus in which a
pulverizer is employed for grinding or comminuting the material, such pulverizer
having an upward discharge communicating through a stack or trunk with our
improved separator. An exhaust fan is connected with the separator and an air
current, laden with the finely divide 1 material, is caused to pass through such
separator in which the gravity separation is effected. The fan, as shown, carries
the finest material into a dust collector of known construction, wherein such fine
material is collected and the purified air escapes back into the pulverizer. In
another form the pulverizer is omitted and the material is delivered into the
separator by means of an elevating conveyor.
In the accompanying drawings:
Figure 1 is a side elevation of the apparatus described.
Figure 2 is an end elevation; and Figure 3 a plan, showing our separator used
in connection with a pulverizer.
Figures 4 and 5 show our improvements as used without the pulverizer, the
material being delivered to the separator by an elevation conveyor.
It will be understood that our invention is applicable for use in connection with
any kind of pulverizing or grinding machinery. The material to be reduced is
delivered into the pulverizer through the hopper 6 and is discharged upwardly
into the stack or trunk 7 by the rotation of the beaters of the pulverizer. The
material is thus cast mechanically upward for some distance into said stack or
trunk, the coarser particles being arrested by the fingers 7 and returning to the
pulverizing chamber to undergo further reduction. These fingers also scatter the
material and thus enable it to be acted upon by the air. To the upper end of
the stack 7 is attached our separator consisting of the outer conical shell 8 having
the closed cover 9 and the inner conical shell 10 arranged concentric to the shell 8
and forming therewith an annular upwardly expanding chamber 11. The walls of
the inner and outer conical shells are substantially parallel to each other as shown,
and are inclined to a considerable degree upward and outward from the lower
contracted portion, thereby giving to the annular chamber 11 a constant and
material increase in horizontal area. The upper end of the cone 10 terminates
slightly below the cap or cover 9 and from the latter depends a conical deflector 12,
the lower edge of which is preferably carried slightly below the upper edge of the
cone 10. Said deflector may be made adjustable. A suction pipe 13 has a flared
opening 14 communicating with the interior of the separator just below the cap or
cover 9, and centrally of the chamber. The open end of this pipe 14 is preferably
above the lower edge of the conical deflector 12 and the upper edge of the cone 10.

page_text: The suction pipe 13 extends through the cones 10 and 11, as shown in Fig. 2, and
is connected with the eye of an exhaust fan 14%. The latter is connected by the
discharge pipe 15 with a dust collector 16, which may be of the "Cyclone" or
centrifugal type. The purified air from this dust collector is discharged through
the pipe 17, having branches 17ª, which lead back to the pulverizer and deliver
into the stack or trunk 7 near its base, so that the material cast up by the beaters
is thrown above the returning air currents. The dust collector may be provided
with a trapped discharge 18 for the separated material.
In the form of construction shown in Figs. 4 and 5 the pulverizer is omitted and
the material is delivered into the stack or trunk 7 through an inlet spout 19 to
which is connected the elevator conveyor 20. A single separator may thus be
connected to a series of pulverizers or the material may be fed from a hopper
by gravity, the inlet for the material being in this construction above the returns
from the fan.
The operation of the apparatus may now be understood. In the construction
wherein the separator is connected directly to the pulverizer, the material being
fed in through the hopper 6 is caught by the rotating beaters, operating within
the pulverizing chamber, and is broken, ground or comminuted, the material both
coarse and fine being cast upwardly into the stack or trunk 7. Of course the
rotation of the beaters generates a strong current of air which is admitted through
the crevices of the machine, if any there be, but preferably through the
independent supply pipe 21. The material which is too large to be carried upon
an air current returns to the pulverizing chamber for further reduction, and the
fan 14 being also in motion induces a strong current of air through the separator.
This current co-operates with the current produced by the rotation of the beaters
and tends to lift the material from the pulverizing chamber, causing it to pass into
the gradually enlarging or expanding chamber 11. The current is strongest of
course in the lower or narrowest portion of this chamber and as the current
gradually expands the heavier particles drop out and return down the inclined
walls of the separator to the pulverizer, while the finer materials pass up with the
air current over the edge of the cone 10, under the edge of the deflector 12 and
thence over the edge of the expanded mouth 14 and into the pipe 13 thence
through the eye of the fan and to the dust collector. The current, as before
stated, becomes weaker in its upward passage through the chamber 11, owing to
the gradual increase in the area of said chamber, and said current as it passes
therefrom over the upper edge of the cone and under the deflector, becomes
rarefied owing to the large area of this portion of the shell as compared with the
area of the chamber 11, and also to the tendency to a vacuum, created by the action
of the suction fan through the suction pipe 13. The air as it passes from the
chamber 11 into the upper portion of the shell is laden with the particles, but on
becoming rarefied, or thinned, as previously stated, said particles are acted upon by
gravity and fall from the air current.
It will be understood that a gradual separation is taking place from the time
that the material borne on the air current enters the lower end of the separating
chamber 11 of the separator and that this separation continues, the coarse
particles being first dropped out and as the current continues to expand its carrying
power becomes less and the separation proceeds until when the current reaches the
top of the cone and is thence deflected under the depending deflector 12 and passes
up into the pipe 13, all of the material except that which has been reduced to a
powder has been separated by gravity. The particles as they are returned to the
separator are delivered at that point where the blast is the strongest, and any
small particles remaining therewith will be removed by the second manipulation.
The walls of the chamber 11 in which is effected a partial separation are, as
previously stated, in substantial parallelism, and the expansion of said chamber is
due therefore to the employment of conical shells which provide a constant and
material increase in the horizontal area of the chamber and insure a gradual
weakening of the ascending air current without fluctuation.

page_text: Now it will be understood that the fineness of the separation will depend upon
two conditions. First, the diameter of the conc; and, second, the volume of air
which is moving through the separator. The walls of the chamber 11 are
necessarily arranged at such angle as to carry the coarse material back into the
pulverizer and the volume of the air current will be proportional to the degree of
fineness desired of the reduced material. For example, if it be desired to save the
material under treatment in the form of an impalpable powder, then the fan will be
adjusted by means of a wind gate or other familiar appliance so as to move only a
small volume of air and at a low velocity through the chamber 11 and the pipe 13.
In its passage from the chamber to the pipe the air current will part with all of the
material except that which is of the fineness desired. By increasing the volume of
air a slightly coarser material can be separated and so on to any desired degree of
fineness. The current which passes over into the dust collector and through the
fan contains one grade of material which it is desired to save, and all that falls
within the cones 10 and 11 may be returned to the pulverizer, or that which falls
within cone 10 may be trapped off and delivered outside of the separator. The
trapped discharge indicated at 21° in Fig. 2 prevents the air from entering through
the tip of the cone. The reduced material is separated by centrifugal force within
the collector 16 and is discharged through the trap 18 into a suitable receptacle. The
purified air is discharged at the upper end of the collector through the pipe 17 and
branches 17 back into the pulverizer.
It will be understood that instead of having the pipe 13 pierce the walls of the
separator, said pipe might be connected with the top of the separator, as indicated
by the dotted lines in Fig. 1. The purified air discharge 17 is provided with an
opening, at 22, which may deliver into a closed separating chamber so as to trap
any dust which is not separated or caught in the separator 16. The major portion
of the air current, however, returns to the air chamber, through the pulverizer or
tailing spout, the opening 22 serving to relieve the system from surplus air taken in
through the pipe 19 and through the shaft bearings or other crevices of the
apparatus.
Our improved separator may be used with other forms of pulverizer and with
other means for taking care of the finished product; as, for example, our separator
may be applied to various kinds of grinding machines, and instead of the dust
collector shown, other types of collectors or separators may be employed. It is
essential, however, to our system to employ some means for inducing an air current
through the separator which air current serves to carry the material in suspension
and effect its gradual separation by the expansion of said current, this expansion
being carried on until only material of the desired fineness is capable of being
supported by the current. Our invention has therefore to do principally with
what may be termed a vacuum or gravity separation, and while the apparatus
before described is arranged so as to use the same current of air continuously,
if it were possible to separate the finished material from the carrying air
current without loss, this continuity of current would not be essential or even
desirable.
Our invention, it will be further observed works with an induced current of air
and it would not be practicable to use a blast fan instead of suction fan to carry the
material through the separators. Furthermore the air current is in all cases
returned below the material.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. A pneumatic separator consisting of an outer conical shell having a closed
head and an opening in its lower contracted portion into which the material to be
separated is delivered, and an air supply opening below said delivery point, an
inner conical shell concentric with and substantially parallel to the outer shell
and providing a gradually expanding annular separating passage communicating

page_text: with the air supply and material delivery openings, said inner shell being open at
its top and terminating below the said closed head, a deflector depending from the
closed head, a separating chamber in the inner shell the area of which is in excess
of that of the passage with which it communicates, a discharge outlet at the
lower end of said chamber, a suction pipe connected to the latter at or near its
upper end, and an exhaust fan connected to said pipe for inducing a current
through said passage and chamber substantially as and for the purpose set forth.
2. A pneumatic separator consisting of an outer conical shell having a closed
head and an opening in its lower contracted portion into which the material to be
separated is delivered, and an air supply opening below said delivery point, an
inner conical shell concentric with and substantially parallel to the outer shell and
providing a gradually expanding annular separating passage communicating with
the air supply and material delivery openings, said inner shell being open at its
top and terminating below the said closed head, a deflector depending from the
closed head and having its lower end in or near the plane of the top of the inner
shell, a chamber in the inner shell the area of which is in excess of that of the
passage with which it communicates, a discharge outlet at the lower end of said
chamber, a suction pipe connected to the latter at or near its upper end, an exhaust
fan connected to said pipe, and a centrifugal separator or dust collector into which
the suction fan discharges, substantially as described.
3. A pneumatic separator consisting of an outer conical shell having a closed
head and an opening in its lower contracted portion into which the material to be
separated is delivered, and an air supply opening below said delivery point, an
inner conical shell concentric with and substantially parallel to the outer shell and
providing a gradually expanding annular separating passage communicating with
the air supply and material delivery openings, said inner shell being open at its top
and terminating below the said closed head, a deflector depending from the closed
head and having its lower end in or near the plane of the top of the inner shell, a
-chamber in the inner shell the area of which is in excess of that of the passage
with which it communicates, a discharge outlet at the lower end of said chamber, a
suction pipe connected to the latter at or near its upper end, an exhaust fan
connected to said pipe, and a centrifugal separator or dust collector into which the
suction fan discharges, and a return pipe for returning the air current from the
dust collector back to the separator at its air supply opening aforesaid, substan-
tially as described.
4. The combination with a pulverizer having an opening leading upward from
the pulverizing chamber, a pneumatic separator mounted upon the pulverizer and
communicating with the said chamber, said separator consisting of two conical
shells concentrically disposed and having their walls in substantial parallelism, the
outer shell having a closed head and an opening in its lower contracted portion
into which the material to be separated is delivered from the pulverizing chamber,
the inner shell terminating below said closed head and providing a gradually
expanding annular separating passage, a separating chamber in the separator the
area of which is in excess of that of said passage with which it communicates, a
discharge outlet at the lower end of said chamber, a suction pipe connected to the
latter at or near its upper end, an exhaust fan connected to said suction pipe, a
centrifugal separator or dust collector into which the fan discharges, a pipe for
returning the air from the dust collector back to the pulverizing chamber, and a
pipe or passage from the inner shell back into the pulverizing chamber, substan-
tially as described.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.