U.S. patent number 3,891,546 [Application Number 05/178,638] was granted by the patent office on 1975-06-24 for helical chute concentrator and method of concentrating.
Invention is credited to Ira B. Humphreys.
United States Patent |
3,891,546 |
Humphreys |
June 24, 1975 |
Helical chute concentrator and method of concentrating
Abstract
A concentrator for separation of particulates of different
specific gravities which embodies a downwardly inclined helical
chute receiving a stream of inter-mixed liquid and particulates at
the upper end thereof. The helical chute has an inner low concave
side wall and an abruptly terminated outer side wall defined by an
upstanding abutment originating at the bottom wall of the
chute.
Inventors: |
Humphreys; Ira B. (Denver,
CO) |
Family
ID: |
22653313 |
Appl.
No.: |
05/178,638 |
Filed: |
September 8, 1971 |
Current U.S.
Class: |
209/159; 209/485;
209/459 |
Current CPC
Class: |
B03B
5/626 (20130101) |
Current International
Class: |
B03B
5/62 (20060101); B03B 5/00 (20060101); B03b
003/04 () |
Field of
Search: |
;209/211,459 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miles; Tim R.
Claims
Having thus described and explained the novel construction and
method constituting my present invention, what I desire to claim
is:
1. An apparatus for concentrating and separately collecting from a
mass of intermixed particles of different specific gravities those
particles having like specific gravity comprising, a stationary
downwardly inclined helical chute, means for feeding an
intermixture of liquid and particles of said mass as a stream to
the upper end of said chute, said chute having an inner low concave
side wall terminating only a little beyond the lowermost point of
the chute bottom and an outer side wall defined by an upstanding
abutment projecting at approximately 90.degree. from the chute
bottom, and the bottom of the chute in spaced relationship
lengthwise thereof and in substantially the said lowest portion
thereof being provided with outlet openings for the discharge of a
portion of said stream and the particles therein.
2. An apparatus for concentrating and separately collecting from a
mass of intermixed particles of different specific gravities those
particles having like specific gravity comprising, a stationary
downwardly inclined helical chute, means for feeding an
intermixture of liquid and particles of said mass as a stream to
the upper end of said chute, said chute having a high and concave
outer side wall and an inner low concave side wall terminating
closely adjacent and beyond the lower-most point of the chute
bottom, an abutment affixed to the chute bottom to project
substantially perpendicularly from the chute bottom at a point
inwardly from the outer side wall, said abutment extending through
a portion of the length of said chute to confine the outermost edge
of said stream therewithin, and the bottom of the chute in spaced
relationship lengthwise thereof and in substantially the said
lowest portion thereof being provided with outlet openings for the
discharge of a portion of said stream and the particles
therein.
3. An apparatus for concentrating and separately collecting from a
mass of intermixed particles of different specific gravities those
particles having like specific gravity comprising, a stationary
downwardly inclined spiral chute, means for feeding an intermixture
of liquids and particles of said mass as a stream to the upper end
of said chute, said chute having an interior which is of a concave
shape in cross-sectional configuration and has its lowest portion
transverse any given point in the length of the chute adjacent to
and spaced inwardly from the inner edge of the chute, an abutment
affixed to the chute bottom to project substantially
perpendicularly from the chute bottom at a point inwardly from the
outer side wall at what would otherwise be the approximate deepest
point in said stream, said abutment extending through a portion of
the length of said chute to confine the outer edge of said stream
therewithin, and the bottom of said chute in substantially the said
lowest portion thereof being provided with a plurality of outlet
opendings in spaced relation lengthwise of the chute for the
discharge of a portion of the inner edge of said stream and the
particles therein.
4. The method of concentrating and separately collecting from a
mass of intermixed particles of different specific gravities those
particles having like specific gravity comprising, mixing particles
of said mass with a liquid and causing said liquid with said
particles therein to flow as a stream in a downward helical course,
confining said stream in a manner to give the stream a deep outer
side edge extending at substantially right angles to the helical
course and a low inner side which from a point within the stream is
of decreasing depth outwardly toward the inner edge of the stream
with a considerable portion of said inner stream side being shallow
and terminating at its edge in a depth which is substantially of
only film thickness and the deepest point in said stream being
positioned closely adjacent and inwardly of the outermost side edge
thereof, continuing said stream travel until the particles therein
stratify in accordance with their specific gravities and assume by
reason of their speed and direction of travel such position that
particles of like specific gravities are in side by side zones
extending longitudinally of the stream with those particles having
the greatest specific gravities in a zone at the inner edge of the
stream and with the remaining zones in a direction toward the high
side of the stream being of progressively decreasing specific
gravity, and thereafter separately removing and collecting from
said stream the particles within each of said zones.
Description
The present invention relates to a method and apparatus for
concentrating ores or the like for the purpose of separating and
separately collecting from a mass those particulates or elements
which have approximately the same specific gravity.
The invention herein disclosed and claimed constitutes an
improvement on my earlier inventions subject of U.S. Letters Pat.
Nos. 2,431,559 and 2,431,560, each dated Nov. 25, 1947.
As in the case of my earlier patents, the novel and inventive
concentrating method of my present invention in broad terms is one
wherein the separation of the particles comprising the mass being
worked is accomplished by intermixing the mass with water or some
other liquid and thereafter directing the liquid containing the
particles through or over a path which will permit the particles
within the stream of fluid to effect a stratification by
gravitational fall of the particles in accord with the specific
gravity of the particles.
Likewise, and as in the case of my earlier patents, the inventive
apparatus concept in broad terms comprises a spiral or helical
conduit which may be either open at one side or completely closed
at all of its sides and which causes the liquid carried particles
to follow a curved path so that in accord with the laws of nature
various portions of the stream of particle-carrying liquid will
assume different speeds of travel and will at all times continue
these specific speeds and assume the same pattern throughout the
travel of the stream. From different sections or parts of the
flowing stream the particles carried by that portion of the stream
are removed by suitable mechanical means.
In addition to the concentration or separation of the particles in
accordance with their specific gravities the method also results in
a classification of the particles, that is, a sizing, in each zone
of concentration, of the particles which have been concentrated
into the several zones within the moving stream. More specific
description of this feature of the method will appear
hereinafter.
More specifically, the novel apparatus for practice of the new
inventive method consists of substantially the identical basic
apparatus as is subject of my earlier patents with one important
modification. The modification referred to consists in a very
significant change in the cross-sectional configuration of the
helical chute of the concentrator, which change in configuration
has been discovered to afford a novel and much improved operational
function when it is desired to attain certain results from the
apparatus.
In even more specific terms the structural configuration of the
helical chute of my earlier invention has been changed to the
extent that the outermost side edge of the chute has been
reconstructed and relocated to effect an operational change in the
apparatus.
It is an object of the improvements of the present invention to
provide a helical chute concentrator in which a reduction in liquid
or water requirement of as much as one-third is effected for
concentrators of the same pitch over the water requirements of
devices of the same purpose known and being part of the prior art,
including my own prior inventions.
A further object of this invention is to provide an improved
helical chute concentrator in which an improved and more effective
classification of the finer and lighter particulates is obtained
over the classification and separation achieved by prior art
apparatus.
It is still another purpose of this invention to provide an
improved helical chute concentrator the construction of which
enables the fabrication and operation of an "entwined" or
"double-chute" unit at advantageous pitch inclinations, at which
pitch prior art apparatus was incapable of such double construction
and, consequently, double capacity operation.
With reference to the accompanying drawings in which like numerals
indicate similar parts throughout the several views:
FIG. 1 is a side elevation of apparatus typifying the present
invention.
FIG. 2 is a fragmentary pictorial view of a helical chute typical
of prior art concentrators.
FIG. 3 is a diagramatic view of liquid flow laterally of a chute of
the prior art construction.
FIG. 4 is a view similar to FIG. 2 of a helical chute of the
present invention.
FIG. 5 is a view of a modified form of the helical chute of FIG.
4.
FIG. 6 is a diagramatic view of liquid flow laterally of a chute of
the construction of FIG. 4.
FIG. 7 is a fragmentary elevation of an "entwined" concentrator as
opposed to the single chute of FIG. 1.
FIG. 8 is a top plan view of the "entwined" structure of FIG.
7.
The inventive method and apparatus is not limited to a
concentration of any particular ores or in the working of a mass
made up of any particular constituents, and fully contemplates the
use of reagent additives to produce the usual agglomeration of ore
particulates within the liquid slurry.
For the purpose only of a better understanding of the present
invention, a description of the concentration of a particular sand
containing minerals will be hereinafter given, which is effectively
the same illustration used in connection with my earlier invention.
The mineral-bearing sand selected for illustrative purposes is a
beach sand found in the State of Oregon which contains particles of
gold, chromite, garnets, and silica. The gold particles have the
highest specific gravity; the chromite the next highest; the
garnets the next highest; and the silica the lowest specific
gravity. The chromite and garnet particles have specific gravities
which are very close to one another and the most difficult part of
the concentration will be between the chromite and garnet
particles. As will appear hereinafter in the specific description
of the operation of the invention, a 100 percent pure concentrate
between chromite and garnet particles is not obtained but the
take-off of chromite particles will consist of a concentrate which
consists almost entirely of chromite and garnet particles and
constitutes a concentrate which is sufficiently high in chromite
particles as to make this concentrate a marketable product.
In operation there will be obtained a very high gold concentrate
and both it and the chromite concentrate will be substantially
entirely free of silica, and tailings discharge at the lower end of
the chute will be practically free of gold and chromite.
Another illustration of an advantageous use of the improved
concentrator herein described, and a specific adaptation wherein
the water savings feature of the present invention is of particular
importance and advantage, is in the concentration and separation of
iron ores in the eastern Canada ranges.
Describing the herein illustrated apparatus in detail and using
like reference numerals and characters to designate similar parts
throughout the following description, A designates a frame or
support for the spiral or helical concentrator channelway or
conduit 10.
The drawings illustrate the frame or support as carrying a single
concentrator but it is to be understood that any number could be
provided in accord with the capacity it is desired that the plant
or installation have in the handling of the illustrative
mineral-bearing sands.
The sand or heads, that is the mass of comminuted particles
containing the particles of chromite and other material, is
suitably mixed, in any desired economical manner, with water or
some other suitable liquid and then this liquid with the sand
therein is forced by a pump 12 or otherwise suitably fed through a
pipe 14 the discharge end 16 of which is disposed within the upper
or receiving end 18 of the spiral or helical conduit or channelway
10.
For convenience and economy both in manufacture and assembly the
spiral or helical conduit is made up of a plurality of open-sided
sections each of which is designated as an entirety by B. Each
section at its ends is provided with a flange 20 and by placing the
flanges of the sections in abutment and bolting or otherwise
suitably securing them together as at 22 a conduit of any desired
length can be quickly assembled.
The number of chute sections employed will determine the length of
the chute or conduit and the length of the conduit will be
determined by the particular material being worked and resulting
concentration obtained. It would, of course, obviously be
unnecessary to elongate the chute beyond a point where any
separation and collection of the particles sought to be recovered
is being obtained. It is also to be recognized that a helical chute
may be formed or cast as a single unit.
In the drawings four convolutions of the chute are illustrated and
the discharge end 24 of the chute carries one of the flanges 20 by
which the chute can be readily elongated should it be found
desirable.
The cross-sectional configuration of the helical chute has been
determined to be critical to attainment of prescribed end results.
In prior concentrators the chute, as illustrated in FIG. 2,
consisted of a low inner side 26 and a high outer side 28 such that
the greatest depth of the stream of liquid (slurry) in the chute
occurs at an intermediate point 30 spaced inwardly from the high
outer wall. Point 30 defines in the chute of my prior inventive
concentrator what becomes identified as the "foam line" in
operation of the apparatus. The foam line occurs at the point
transversely of the chute where a division occurs in the lateral
flow patterns of liquid while progressing downwardly
(longitudinally) of the chute. The foam line occurs laterally of
the chute at what is also the approximate deepest point of liquid
stream in the chute. These internal flow patterns are illustrated
by arrows C and D in FIG. 3 of the drawings. Arrows C indicate the
pattern of internal flow from the low side of the chute outwardly
to the foam line, and arrows D illustrate the pattern of internal
flow from the foam line at point 30 outwardly to the highest side
above the chute.
In operation of the helical chute concentrator typifying the prior
art and as illustrated in FIGS. 1 through 3 of the drawings, the
stream of water or other liquid bearing the mixed particulate
material to be concentrated is introduced into the spiral or
helical chute at the upper end 18 thereof through the feed pipe
14.
At separated points along its inner and lower wall 26 the chute is
provided with draw-off holes or openings 32 through which the
concentrated particles having closely similar specific gravities
are progressively discharged to a suitable point of collection, as
will hereinafter more fully appear. These draw-off holes are
illustrated as being circular in shape but they could be oblong or
shaped otherwise without detrimentally affecting the practice of
the method. Each draw-off hole is provided with a movable splitter
disc 32a which enables control of the amount of material discharged
at that point. The number of draw-off holes provided is optional,
but one in each of the chute sections B has been adopted for
convenience in manufacture. The number of draw-off holes and the
spacing of them in respect to one another is optional and would be
varied if need for variation were found by reason of the particular
material being operated upon; or the desire of separating and
collecting a plurality of concentrates of different materials; or
the desirability of the collection, for reworking, of a plurality
of middlings.
The material to be concentrated and separated can be mixed in any
convenient manner with the water or other liquid. In FIG. 1 of the
drawings this is illustrated as being accomplished by supplying
water from any convenient source through a pipe 34 to a hopper 36.
The material to be worked is dumped into the hopper and the
intermixed water and material is drawn from the hopper through the
pipe 14 by the pump 12.
The concentrates which are withdrawn from the take-off or outlet
openings 32 can be collected in any suitable and convenient manner.
In FIG. 1 of the drawings the collected concentrates are
illustrated as being conveyed from the first utilized two take-offs
by pipes 38 and 40 to a main conduit 42 which serves to convey the
concentrates to a point (not shown) for collection.
Similarly the next utilized two take-offs are connected by conduits
44 and 46 to a main conveyor discharge conduit 48 and the remaining
last utilized two take-offs are connected by pipes 50 and 52 to a
conveyor conduit 54.
The specific arrangement for conveying the concentrates to a point
of collection could and probably would vary in accord with the
particular material being sent through the concentrator. The
arrangement illustrated is suitable for working the particular ore
bearing sands hereinbefore referred to, as will be made clear from
the following description of the operation of the method.
The size or volume of the stream of particles carrying liquid in
respect to the cross sectional area of the chute is such that the
chute is not completely filled with the stream. The size of the
stream is regulated so that at its inner and lower edge, where the
stream is running over or on that portion of the chute adjacent its
lower and inner side, it is comparatively shallow with the result
that a thin or shallow zone or film of intermixed solid material
and liquid is moving over the chute at its inner lower side. It is
at this side of the chute and in this shallow part of the stream
that the particles within the stream having the greater specific
gravity concentrate to be periodically drawn off, as will
hereinafter appear.
All parts of this stream or material carrying liquid do not require
the same speed of movement in the passage of the stream down, along
and through the helical or spiral chute. Neither do the comminuted
particles carried by the stream of liquid all acquire the same
speed of travel through and along the chute.
Promptly after the introduction of the solid material carrying
liquid into the chute the particles making up the solid material
will stratify according to specific gravity with the result that
those particles having the greater specific gravity will move to
the bottom of the stream of liquid and these particles also in
response to the force of gravity will move to the inner and lower
side of the chute, with the result that the stream, after traveling
a short distance, is composed of several zones each of which
contains those particles having substantially the same specific
gravity.
Those portions of the traveling stream of liquid which are on the
bottom of the stream and in contact with the bottom of the chute
and at the lower inner side will travel the slowest. The particles
having the greater specific gravity will for the foregoing reasons
sink to the bottom of the traveling stream of liquid and move to
the lower and inner side of the chute.
It will be understood that the water or liquid, like the particles,
responds in its movement to the force of gravity and that as a
result the water on the bottom of the stream will have some
tendency to move from the high to the low side of the stream and
that this movement in response to gravity will set up in the stream
a movement transverse the stream and transverse the forward and
downward movement of the stream. This transverse movement of the
water will assist in moving the particles of high specific gravity
toward the inner lower side of the stream and to the inner lower
side of the chute, all as explained above.
Those particles having the lesser specific gravity will be in the
faster moving portions of the stream of liquid and will travel
therewith and away from the particles having the higher specific
gravities.
As the stream of water with the solid material therein progresses
downwardly through the spiral chute the lighter materials or
particles having the lesser specific gravity will move along with
the faster flowing portion of the stream and the remaining material
will arrange itself within the stream in zones according to the
specific gravities of the several particles making up this
material.
The particles of different specific gravities will arrange
themselves in the zones as described by reason of a natural
stratification which causes those particles having the highest
specific gravities to be positioned in the slowest moving stream or
zone of the stream. These heavier particles will concentrate in
these zones because they will as the stream moves through the chute
gradually work to the inner and lower side of the chute by moving
under the faster moving portion of the stream which is carrying
with it the lighter materials. Actually the comminuted particles
assume a position in the chute and stream which is determined by
their velocity down the chute and this pattern of operation and
concentration is not disrupted or distrubed by the admission of
liquid and material to the upper end of the spiral and the pattern
is altered only progressively by the removal of concentrates from
or through the inner lower side of the chute. The concentrates are
removed and collected progressively in accord with their specific
gravities.
The improvement of the prior art devices which constitute the
present invention is best illustrated in FIGS. 4, 5 and 6 of the
drawings. In FIG. 4 of the drawings there is illustrated a helical
chute configuration which is substantially identical to the
configuration of the chute shown in FIG. 2 illustrative of the
prior art with the important exception of the provision in the
construction of FIG. 4 of an abutment strip 56 which is secured to
the bottom wall of the chute to project upwardly therefrom at a
point in the bottom wall which substantially coincides with point
30 shown in FIG. 2 of the drawings as being the approximate
positioning of the foam line occurring in operation of a helical
chute constructed in accordance with the prior art. The abutment
strip 56 may extend continuously through each segment or section of
the chute, or selectively it may extend through only a portion of
the entire length of the concentrator chute. The abutment strip of
FIG. 4 may be formed of any semi-rigid material such as hard rubber
or the like, and may be permanently, or removably secured to the
bottom of the chute to provide a confining partition for the liquid
material flowing down the chute for purposes to be hereinafter
explained.
In FIG. 5 of the drawings there is shown a helical chute
construction which is modified from the construction typifying the
prior art as is illustrated in FIG. 2 in that the upper outer wall
of the chute is shaped as at 58 to provide a confined abutment
substantially identical in configuration to the abutment strip 56
heretofore described in reference to FIG. 4. In the modified chute
construction of FIG. 5 the length or extent of the upper outer wall
of the prior art chute construction of FIG. 2 is shortened so that
the lateral dimension of the chute bottom from the base of the wall
abutment 58 to the lower inner edge of the chute 26 in this form is
substantially identical to the lateral dimension defined between
the inner base edge of the abutment strip 56 of FIG. 4 to the lower
inner edge 26 of the chute of that same construction.
It has been discovered that certain advantageous results occur by
confining the downwardly flowing stream inwardly of the chute
construction of the prior art in the manner by which the abutment
strip 56 of FIG. 4 or the reconstructed outer wall 58 of FIG. 5
will confine the liquid stream in those particular configurations.
The resulting change in the internal flow laterally of the chute is
illustrated in FIG. 6 of the drawings wherein arrows E and arrows F
represent the internal flow corresponding to arrows C and D,
respectively, illustrated in FIG. 3 of the drawings. What is seen
to result is a substantial reduction in the area of liquid outside
of the foam line over the prior art structure, and it is seen that
the foam line 60 of the chute construction of FIG. 6 is displaced
only a short distance inwardly from the abutment strip 56 thereof
when measured proportionately to the inward relocation of the outer
extremity of the flowing stream in respect to its positioning in
the prior art structure.
By reason of the ability obtained by the heretofore described
modification of the helical chute to relocate the outer extremity
of the flowing liquid stream without any marked change in the
location of the foam line, and hence without any marked reduction
in the principal working area of the stream, it may immediately be
seen that a substantial savings in the quantity of water or other
liquid necessary to be mixed with the particulate material is
accomplished. This ability to reduce water requirements is of vital
importance in many geographical areas where water availability is
minimal and where the cost of it can be an important factor in the
operation of concentrators of the type herein described.
Additionally, any percentage of reduction of water requirements
produces a corresponding reduction in the equipment and power
required to pump liquid in the concentrator apparatus.
In many installations it is desirable, because of limited space
availability, to construct spiral concentrators of the type herein
described in a double or "entwined" arrangement. A fragmentary
segment of such a concentrator assembly is illustrated in FIG. 7 of
the drawings wherein one helical chute 62 is interposed between the
convolutions of a second helical chute 64.
It has also been determined through experience that the most
favorable operational inclination of a helical chute in the
majority of concentrating operations encountered is at a pitch of
131/2 inches, but it has also been found essential, in order to
attain sufficient working room between the helical chutes, to
increase that pitch to 171/2 inches for those helical chutes
assembled in "entwined" or double construction as illustrated in
FIGS. 7 and 8. Thus, in double chute constructions heretofore
optimum operating conditions have been sacrificed in order to
attain a savings in space requirements for assembly of the
concentrators. By utilization of the improved concentrator
construction herein disclosed in FIG. 5 of the drawings, it is seen
that the height and extent of the higher outer side of the chute
has been reduced, and this reduction from the dimensions of the
prior art has been discovered to permit the assembly of an
"entwined" or double construction as illustrated in FIG. 7 at the
optimum pitch of 131/2 inches with retention or provision of
adequate work room between the convolutions which was not available
or attainable under the prior art.
It has been additionally discovered, as is best seen from the
liquid flow diagramatically illustrated in FIG. 6 of the drawings,
that a small fraction of the finest concentrates which are normally
stratified in the outer-most boundary of the liquid stream which,
in the prior art construction, would be beyond or outwardly from
the foam line are substantially retained by the present invention
within the operating area of the flowing stream and are thereby
normally recovered as opposed to being lost in a single pass of the
liquid through the concentrator.
* * * * *