U.S. patent number 3,877,650 [Application Number 05/443,860] was granted by the patent office on 1975-04-15 for partition for tumbling mills or the like.
This patent grant is currently assigned to Aerofall Mills Limited. Invention is credited to Arthur Selwyn Cornford.
United States Patent |
3,877,650 |
Cornford |
April 15, 1975 |
Partition for tumbling mills or the like
Abstract
A tumbling mill or like apparatus having a generally
horizontally mounted rotary drum along which a charge is caused to
flow from a first zone of the drum to a second zone includes an
intermediate zone at which an additional material is introduced
into the drum to be added to the charge. Deflector means in the
intermediate zone ensure that the charge and additional material
proceed to the second zone, the deflector means providing a trap to
prevent material from passing back to the first zone. The
additional material may be a gas or vapour, or a solid or liquid
material or slurry.
Inventors: |
Cornford; Arthur Selwyn
(Clarkson, Ontario, CA) |
Assignee: |
Aerofall Mills Limited
(Ontario, CA)
|
Family
ID: |
23762474 |
Appl.
No.: |
05/443,860 |
Filed: |
February 19, 1974 |
Current U.S.
Class: |
241/71; 241/72;
241/43; 241/172 |
Current CPC
Class: |
B02C
17/06 (20130101) |
Current International
Class: |
B02C
17/00 (20060101); B02C 17/06 (20060101); B02c
017/06 () |
Field of
Search: |
;241/171,176,180,183,54,57,42,71,72,43 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
579,186 |
|
Sep 1931 |
|
DD |
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590,220 |
|
Jul 1932 |
|
DD |
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Primary Examiner: Lake; Roy
Assistant Examiner: Desmond; E. F.
Claims
What I claim as my invention is:
1. In an apparatus comprising a horizontally mounted rotary drum
along which a charge is caused to flow from an upstream zone of the
drum to a downstream zone which is axially spaced from the upstream
zone, means defining an intermediate zone at which an additional
material may be introduced into the charge, said means
comprising
a plurality of axially spaced transverse drum partitions defining
first, second and third lifting chambers,
the first chamber including inlet means communicating with said
upstream zone for admitting charge from the upstream zone to the
first chamber, outlet means communication with a central region of
the second chamber, and conical deflector means extending axially
across the first chamber for substantially the entire axial length
thereof, said conical deflector means cooperating with said outlet
means for deflecting charge from the first chamber to a central
region of the second chamber,
the second chamber including outlet means communicating with the
third chamber, and annular deflector means extending axially across
the second chamber for substantially the entire axial length
thereof, said annular deflector means defining an annular region of
the second chamber partitioned from the central region,
the second chamber further including peripheral inlet means
communicating with said annular region for the admission of
additional material thereto,
the annular deflector means providing a pair of inner and outer
frusto-conical deflector surfaces cooperating with the outlet means
of the second chamber for deflecting charge from said central
region, and material from said annular region, into the third
chamber,
the third chamber including outlet means communicating with said
downstream zone and conical deflector means extending axially
across the third chamber for substantially the entire axial length
thereof, said conical deflector means cooperating with the outlet
means of the third chamber for deflecting the charge and said
additional material therethrough.
2. Apparatus according to claim 1, wherein the chambers are defined
by first, second, third and fourth drum partitions, the first drum
partition including an annular grid defining said inlet means, and
said outlet means being defined by respective openings in the
second, third and fourth partitions, said grid, said openings, and
said defector means being coaxial with one another and with the
drum.
3. Apparatus according to claim 1, including an annular casing
encircling the external surface of the drum at said intermediate
zone and defining therewith a manifold communicating with said
peripheral inlet means, and means for supplying a gas to the
manifold.
4. Apparatus according to claim 1, including an annular casing
encircling the external surface of the drum at said intermediate
zone and defining therewith an annular chute communicating with
said peripheral inlet means, means for supplying heavier than air
material to the chute, and scoop means connected to the drum and
rotatable therewith for conveying said material to the peripheral
inlet means.
Description
This invention relates to tumbling or grinding mills, rotary kilns,
dryers, and the like, and more generally to apparatus of the kind
having a horizontally mounted or slightly inclined rotary durm
along which a charge is caused to flow. The drum is usually of
cylindrical or conical shape. Such apparatus is extensively used in
the mineral and metallurgical process industries. In the majority
of cases, the drums are fed and discharged continuously and
openings are provided at the axial extremities of the drums for the
ingress and egress of solids and/or fluids such as water, hot gas,
and the like.
In some cases it may sometimes be desired to carry on two or more
stages of the process in sequence within the same drum. One example
of such a requirement is a two-stage grinding process in which
coarse grinding is performed, using large grinding media, in the
upstream end of a ball mill and fine grinding, using smaller
grinding media, is performed in the dowstream end of the mill. A
diaphragm partition is usually used to keep the two sizes of media
separate, the diaphragm partition being provided with slots through
which the charge can pass.
Furthermore, it is usually advantageous to ensure that the charge
will flow through the diaphragm in one direction only, i.e.
downstream. This is usually accomplished by constructing a
partition with two diaphragms spaced several inches apart, the
upstream diaphragm being provided with slots for passage of the
charge and the downstream diaphragm having a central opening of
comparable size to the main feed and discharge openings of the
drum. The space between the diaphragms is divided into a number of
compartments by means of radial vanes or lifters, whose function is
to elevate material as the drum rotates, the lifted material
sliding down the lifter radially towards the centre of the mill
shell. A conical deflector is provided at the axial centre of the
diaphragm to deflect the material from the lifters to the outer,
downstream side of the partition. In other cases it is sometimes
advantageous to discharge process material or charge from a
rotating drum through ports around the periphery of the drum rather
than through an end discharge opening. In such a case, when
grinding media have to be ratained within the shell, it is usual to
provide a single slotted grate diaphragm, without lifters, through
which the material can flow and hence through the peripheral
ports.
It is an object of the present invention to provide an apparatus
with provision for introducing solids or fluids into the rotary
drum, at an intermediate point between the ends of the drum,
without accidental discharge of materials already inside the
drum.
According to the invention there is provided in an apparatus
comprising a horizontally mounted rotary drum along which a charge
is caused to flow from an upstream zone of the drum to a downstream
zone which is axially spaced from the upstream zone, means defining
an intermediate zone at which an additional material may be
introduced into the charge, said means comprising a plurality of
axially spaced transverse drum partitions defining first, second
and third lifting chambers, with deflector means for deflecting the
charge and additional material through the chambers towards the
downstream zone, the deflector means providing a trap for
preventing the passage of material back to the upstream zone. The
additional material may be a gas or vapor, or a solid or liquid
material or slurry.
In order that the invention may be readily understood, two
embodiments thereof will now be described, by way of example with
reference to the accompanying drawings, in which:
FIG. 1 is a side elevation of a tumbling mill having means for
introducing a gas or vapour at an intermediate zone of the
mill;
FIG. 2 is a cross-sectional view of the mill, the section being
taken through the intermediate zone, and certain parts being broken
away to show details of said zone;
FIG. 3 is a longitudinal sectional view showing details of the
intermediate zone;
FIG. 4 is a longitudinal sectional view corresponding to FIG. 3 of
a modified apparatus having means for introducing solids or
slurries at the intermediate zone, and
FIG. 5 is a cross-sectional view corresponding to FIG. 2 of said
modified apparatus.
Referring to FIG. 1, the tumbling mill comprises a horizontally
mounted rotary drum 10 of cylindrical shape, the drum being mounted
on bearings 11, 12, and being rotated about its horizontal axis by
a drive motor 13 through a pinion 14 and spur gear 15. The drum has
an inlet opening and a discharge opening at its opposite ends. The
charge, or material to be processed, is fed into an upstream zone
16 of the drum by way of a charging chute 17, and processed
material is discharged from a downstream zone 18 of the drum by way
of a discharge chute 19, a conical deflector 20 being positioned
adjacent to the discharge opening and combined with grates and
lifters for discharging material into the discharge chute in the
known manner.
Positioned between the upstream and downstream zones 16, 18 is an
intermediate zone 22 into which an additional material, in this
case a gas, may be introduced to be added to the charge. The
details of the intermediate zone are shown in FIGS. 2 and 3.
Essentially, this zone is formed by a plurality of, in this case
four, axially spaced, transverse drum partitions 23, 24, 25, 26,
which define a plurality of chambers, in this case first, second
and third lifting chambers 27, 28, 29. The first partition 23 is
formed by a slotted grid which defines an inlet to the first
chamber 27. Ground material of a suitable size, or slurry or the
like, can pass from the upstream drum zone 16 through the grid into
the first chamber 27. The central portion of the partition 23 is
connected to, or formed integrally with, a conical deflector 30
which extends axially for substantially the full axial length of
the first chamber 27. Radial lifters 31 extending from the conical
deflector 30 serve, as the drum 10 rotates, to lift material in the
chamber 27, which material descends by gravity onto the deflector
to be deflected thereby through a central outlet 32 in the second
partition 24. It will be appreciated that the lifters 31, and the
lifters 21 and 40 referred to below, need not be straight as shown,
but may be curved to suit the flow characteristics of the material
in passage. The second partition 24 is formed with an annular
deflector 33 which extends axially for substantially the entire
axial length of the second chamber 28. This deflector has a
frusto-conical outer surface and a frusto-conical inner surface,
the latter defining a central region 28a of the second chamber 28,
which central region is partitioned by the deflector from the outer
annular region of the chamber. Process material discharged into the
central region 28a of the second chamber strikes the inner
frusto-conical surface of the deflector 33 to be deflected thereby
into the third chamber 29. Lifters 21 are provided in the second
chamber. Their function is to scavenge materials which may be
accidentally deflected from the third chamber and to prevent them
from being discharged via inlet openings 34.
Gas or vapour to be added to the charge is introduced into the drum
by way of the peripheral inlet openings 34 which communicate with
the annular region of the second chamber 28. These openings
communicate with a manifold formed by an annular casing 35 which
encircles the drum. Gas or vapour is supplied to the manifold, at a
pressure which is higher than that existing in the downstream zone
18 of the drum, by way of an inlet duct 36, and since the casing is
stationary, annular seals 37, 38 mounted on the drum prevent
leakage of the gas or vapour as the drum rotates. The flow of gas
may be induced by means of an exhaust fan on the outlet side of the
drum.
Gas from the annular region of the chamber 28 is discharged through
an outlet 39 in the partition 25 into the third chamber 29. Process
material deposited into the third chamber is lifted by radial
lifters 40 extending from a central conical deflector 41, the
deflector 41 extending substantially for the full axial length of
the third chamber and cooperating with a central opening 42 in the
fourth partition 26. The process material, having been lifted is
deposited onto the upper surface of the deflector 41, and is
deflected thereby into the downstream zone 18 of the drum. In this
way, gas or vapour is introduced to the drum to be added to the
charge, the intermediate zone being so arranged as to prevent the
charge from returning from the intermediate zone to the upstream
zone of the drum.
The modification illustrated in FIGS. 4 and 5 differs from the
preceding embodiment in that means are provided for adding a
heavier-than-air material, such as a granular solid or a slurry, to
the charge at the intermediate zone. In these Figures, parts which
have exact counterparts in FIGS. 2 and 3 are denoted by the same
reference numerals. In this case, however, instead of there being
gas or vapour admitted to the drum, a granular solid or a liquid is
fed by a chute 43 into an annular chute 44. The annular chute is
formed by an annular casing which encircles the intermediate zone
of the drum 10. The heavier-than-air material descending into the
chute 44 is scooped up by scoops or buckets 45, lifted, and
deposited into the second chamber 28 of the intermediate zone via
peripheral openings 46. The casing 44, which is stationary,
cooperates with rotary seals 47, 48 to prevent leakage of the
additional material as the drum rotates.
As will be appreciated by those skilled in the art, in certain
applications the axis of the drum may not be truly horizontal, but
may be slightly inclined to the horizontal to assist the flow of
material. Such cases are considered to be within the scope of the
invention. Accordingly, the expression "generally horizontally
mounted rotary drum" as used in the specification and claims is
intended to mean a rotary drum which is mounted so that its axis of
rotation is horizontal or slightly inclined to the horizontal.
Furthermore, it is to be understood that the terms "conical" and
"frusto-conical", as applied to the deflector surfaces of the
"conical deflectors" and the "annular deflector" are not restricted
to shapes which are conical and frusto-conical in the strict
mathematical sense. In the illustrated embodiments the surfaces
described by these terms are essentially flared surfaces of
revolution which are approximately conical and frusto-conical, and
the said terms as used in the specification and claims are deemed
to described such shapes.
* * * * *