Improvements in Dry Concentrators for the Treatment of Ores.
Year: 1888

page_text: Date of Application, 20th Oct., 1888
Complete Specification Left. 24th June. 1889-Accepted, 27th July, 1889
PROVISIONAL SPECIFICATION.
Improvements in Dry Concentrators for the Treatment of Ores.
I, CHARLES NOE BENJAMIN WETZLAR, of 170 New Bond Street, in the County of
Middlesex, Gentleman, (a communication to me from abroad by William Legrand
Card, of La Crosse, (Wisconsin) in the United States of America, Mining Engineer)
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide simple, efficient, and compact means or
mechanism for the concentration of pulverized ore by the dry (or air) process.
The main elements embodied in a preferred form of machine are, an air chamber,
an ore bed, a vacuum chamber, a refuse chamber, an air box, an exhaust fan, and
various adjuncts thereto; and the invention consists in certain. combinations of two or
more of such elements, and also in particular features of construction of several of
said elements, all as will be hereinafter mentioned.
ог
The machine consists of a suitable framework, adapted to support the working
operative parts of the machine, in which I provide a main or supply hopper which
receives from the sizing screen the material to be operated on, said hopper having a
suitable slide or gate. Between this hopper and the ore bed is a feed hopper which
is preferably arranged or formed in one end of the case of the vacuum chamber, the
wall of said feed hopper having a flange which supports the free end of the cover of
the said vacuum chamber. The bottom of the feed hopper is controlled by an
adjustable slide or feed-gate. The front of the slide or feed gate has a series of
rectangular open slots bordered by downwardly projecting flanges. By this con-
struction, the size of the series of openings in the bottom of the feed hopper can
be varied, as required, and, at the same time, the material is fed across the ore
bed in an interrupted or broken line (and not continuously as heretofore) with
intervals or air spaces which permit the free passage of air and prevent the air
currents from interrupting and destroying the regularity and uniformity of the
feed.
The ore bed has its independent frame arranged upon, and secured to, though
detachable from, a horizontally vibrating frame to which it is usually secured by end
wedges.
The construction of the ore bed is as follows: Any perforated material-preferably
steel wire netting, having openings (or mesh) larger than the screen which has been
used to sort or size the material to be concentrated-is corrugated or bent to form
a series of hills and valleys or alternate reverse inclines, and is then secured to
the bed frame in any suitable manner. For purposes of convenience in construction
I sometimes prefer to construct the bed frame of two sections having serrated or
zig-zag lines of separation, intermatching side bars, said zigzag lines of separation
corresponding to the hills and valleys of the screen. If this construction be not
adopted the side bars of the bed frame should be recessed to receive the edges of the
perforated material.
The rear end of the ore bed has a bridge piece or end plate upon which, by
means of suitable set or thumb screws, is secured an adjustable inclined plate which
projects over the end of the ore bed, and back of said adjustable plate, the bridge
piece being slotted so as to provide a throat or exit for the debris or waste which
passes off from the ore bed.
Within a case or box, which rests upon the frame of the ore bed, is suspended the
cover of the vacuum chamber, its free end resting on the before mentioned flange of
the hopper wall, while its opposite end is adjustablý suspended from a cross piece of
the case or box, by means of a threaded rod. This cover is preferably of glass set in

page_text: a suitable frame as thereby the ore bed is rendered constantly open to inspection-The
ore bed itself is covered by, or constituted of, a layer of shot, or perineable material of
equivalent size.
The function of the corrugated perforated sheet or wire gauze bottom, with its
transverse hills and valleys, is to give to the shot, or other material, constituting the
bed, a vertical jigging motion, while the reciprocation of the frame gives the same
horizontal motion; the function of the adjustable cover of the vacuum chamber is to
increase or decrease the velocity of the longitudinal air currents which pass over the
ore bed, and it will be at once apparent that, as the cover is raised by the screw rod
to increase the angle between the bed and cover, as well as the size of the vacuum
chamber, said air currents must decrease in velocity, while when the cover is lowered
the reverse must occur. The function of the adjustable plate at the end of the ore
bed, and extending over the same, is to increase or decrease the depth of material
retained on the bed accordingly as the character of the material requires it to be
treated in thick or in thin strata to be slowly or rapidly worked off the bed-or
whether a slow or a rapid discharge of the refuse is desired.
Immediately beneath the ore bed supporting and carrying the same, resting on
spring supports and the refuse chamber, is a horizontally vibrating or reciprocating
frame the two side pieces of which are connected at one end by a cross piece having
a transverse slot corresponding with the slot of the ore bed, and said piece is faced on
its under side with a metallic plate which moves over a suitable packing-preferably
felt, applied to the top of the refuse chamber. At the opposite ends, the side pieces
of the vibrating frame are connected by a cross piece from which flexible steel spring
straps extend down to a cross piece on the sills of the main frame, the said straps
being bolted to both the cross piece of the vibrating frame and the main frame.
Arranged over, and bolted to the said cross pieco is a second cross piece from which
flexible steel straps extend together encircling eccentrics or cams on the driving
shaft, whereby the frame and ore bed are vibrated.
The air enters this machine through the air chamber or chamber below the ore bed,
and this chamber might also be called the concentrator chamber as it receives all the
concentrates which pass through the ore bed. The said air chamber is formed with
an inclined bottom to discharge the concentrates, and is divided up near its bottom
into a series of separate shoots by vertical partitions. In order to obtain free access
to this air chamber one side thereof may be partially closed by a detachable door or
side piece and the space above said door, through which the air enters, may be closed
by a wire gauze screen.
In line with the air chamber and likewise below the ore bed, is the refuse chamber
whose bottom is double inclined or hopper-shaped, and has arranged therein a worm
or screw conveyer which discharges the refuse through a port in the side of the said
chamber into an overflow box of such height as to keep the refuse chamber constantly
closed or sealed which is necessary because this chamber in the present application of
the invention is placed between the ore bed and an exhaust fan. In the cover of the
refuse chamber are two slots or ports one of which establishes communication
between the vacuum chamber (over the ore bed) and the other establishes com-
munication between the refuse chamber and an air box interposed between said
chamber and the exhaust fan. This latter port may be provided with a valve to
control the size of or close its port at will.
Located over the refuse box, and communicating therewith, is the air box having a
tube or flue extending from the top thereof to the eye of the exhaust fan. This air
box is provided with two ports the first for admitting at times a continuously
regulated volume of air to the air box, to control the force of the exhaust (or vacuum)
exerted by the fan in the vacuum chamber and through the ore bed; the second to
intermittently, partially, or wholly destroy the vacuum in the vacuum chamber so
that the machine can be made to operate as a gravity concentrator and a simple
screen, alternately, that is to say by the vacuum over and air jets through the bed,
when this second port is closed, and by simply screening when said port is open and

page_text: the vacuum destroyed. The first port which may extend nearly across the air box is
covered with wire gauze and silk netting, or any fine fabric, may also be used to
cover the wire netting and temper the force of the air currents. With this port an
ordinary adjustable gate or slide valve may be used. The second port for the
intermittent currents requires to be of different construction because both the volume
and frequency of the air admitted to destroy or trouble the vacuum in the vacuum
chamber must be altered to suit different material; therefore said port is formed by
means of a transverse slot extending across the rear side of the air box in which are
arranged slides which may be moved to or from each other to increase or diminish
the size of the second port. In order to close this port a valve is used and is
hinged on one side; at its opposito side it is provided with a spring to draw it
to its seat. It is furnished with an adjustable tongue which stands in the path of
a tappet on a rotating shaft by means of which said valve may be intermittently
opened. The equivalent of the valve described would be any of the well known
tappet or puppet valves. A simple construction of the tappet is made by a slotted
shaft receiving an adjustable steel blade secured by set screw. By adjusting this
blade so that the opposite tappets are of equal length a regular intermittent opening
of the valve twice at every revolution of its shaft can be obtained, while by
varying the length of the opposite tappets in the adjustment of the blades the
valve may be held open longer at one lime than at the other, or may be entirely
missed by one tappet so as to be opened only once in each revolution of its shaft.
Thus by a proper manipulation of the valve, and of the three ports, herein before
described, a great variety of changes may be effected in the operation of the machine
so as to adapt it to treat an infinite variety and character of material.
Within the air box, and extending across the same, over the slot or port in the
cover or top of the refuse chamber, and above the bottom of the air box, is a
triangular baffle bar to break up the direct air current from the refuse chamber to
the fan.
Certain of the herein before mentioned parts, viz. the horizontally vibrating frame,
the worm or screw conveyer, the valve binged on one side and provided on the other
with a spring, and the exhaust fan, require motion imparted to them, and for this
purpose any suitable gearing may be employed.
The machine is provided with a main shaft on which is mounted a drum receiving
the power belt and which, through the flexible steel straps, vibrate the frame above
mentioned. This shaft may have a balance or fly-wheels and is provided with two
pulleys one of which, through a belt, drives the fan, while the other, through another
belt, drives the shaft on which is the tappet, and this latter shaft in turn, through a
belt, drives the conveyer shaft. As the speed of the tappet and the conveyer require
to be altered from time to time, according to the material operated on, cone or cluster
pullies are employed..
The devices being of substantially the construction herein described will operate as
follows: Power being applied to drive the exhaust fan, to vibrate the frame, and the
ore bed therein, and to operate the tappet and the conveyer, the valve of the feed
hopper is set to give the desired feed of material to the ore bed. The material, owing
to the described construction of the valve or slide of said feed hopper, flows on the
bed in parallel streams which do not interrupt the flow of the air between the feed
hopper and the ore bed. On reaching the bed the material spreads out and flows
thereover in a regulated stratum where it is subjected to minute up-flowing jets of
air which enter the ore bed from the air chamber and permeate the bed and the
super-imposed stratum of material to be treated, permitting the concentrate to sink by
gravity into and through the bed and fall into the air chamber, whence it escapes and
is collected, as before stated. The passage of the minute air jets into the vacuum,
and thence over the ore bed, through the proper ports, into the refuse chamber, causes
the flow of the debris, waste, or refuse, with it into said refuse chamber wherein the
heavier gritty matters are deposited by gravity to be gradually pushed out of the
refuse chamber into the overflow box by the conveyer, only the lighter and harmless
dust being permitted to enter the fan.
:

page_text: The feed gate or valve of the feed hopper, the vacuum chamber cover, the adjustable
plate, the slot or port between the refuse chamber and the air box, the gate or slide
valve of the port covered with wire gauze, the slides of the port for the intermittent
currents, the adjustable tongue and the tappet operating the valve having all been
adjusted to adapt the machine to the size and character of the material to be operated
upon, the result will be as follows: During the interval that the valve operated by
the tappet is closed, the upflowing jets of air, through the ore bed and super-imposed
pulverized ore, have tho effect stratifying the mass with the heavier or mineral
particles at the bottom and the lighter or gangue particles at the surface, while the
longitudinal flow of the air, caused and regulated by the cover of the vacuum
chamber, carries the surface of the mass (composed of gangue) towards the discharge
end of the vacuum chamber, thus permitting a corresponding quantity of pulverized
ore to enter through the feed gate or valve of feed hopper. But the moment the
valve operated by the tappet is opened, these conditions are partially or wholly
suspended, while the sifting is continuous though less rapid while the stratification is
taking place because, at such time, it is retarded by the air flowing upward through
the ore bed.
1000
ERNEST DE PASS, Fel. Inst. P.A.,
68, Fleet Street, London, Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Dry Concentrators for the Treatment of Ores.
I, CHARLES NOE BENJAMIN WETZLAR, of 170 New Bond Street, in the County
of Middlesex, Gentleman, 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, reference being had to the accompanying drawings
and to the letters and figures marked thereon, that is to say :-
The object of this invention is to provide simple, efficient and compact mechanism
for the concentration of pulverized ore by the dry (or air) process, and will be
readily understood on reference to the accompanying drawings in which:
Figure 1 is a side elevation of a dry concentrator embodying my invention.
Figure 2 is a left hand end view of Figure 1, or the feed end of the machine.
Figure 3 is a view of the opposite end of the machine, or that end where the debris
or waste is discharged.
Figure 4 is a vertical transverse section of the machine, on the line a, a of Figure 1,
looking in the direction of the arrow.
Figure 5 is a similar section on the line bb of Figure 1, looking in the same
direction.
Figure 6 is a vertical longitudinal section of the machine on the line c, c of
Figure 2.
Figure 7 is a detail sectional view illustrating the manner in which the vibrating
bed frame is packed where it rests and moves on the refuse chamber.
Figure 8 is a plan view of the air chamber below the bed, the bed having been
removed to show the vibrating frame, and the air box of the exhaust fan having
been cut through on the line d, d, of Figures 1 and 6.
Figure 9 is a detached plan view of the ore bed and its adjustable cover, and the
feed hopper.
Figure 10 is a bottom view of the ore bed alone.
Figure 11 is an enlarged view of the cam or tappet for actuating a valve.
Figures 12 and 13 are enlarged detail views shewing the construction and
arrangement of the feed gate of the small hopper 6 (see left of Figures 6 and 9.),
Figures 14 and 15 are enlarged detail views showing the construction of the
ore bed.
Like figures refer to like parts wherever they occur.

page_text: are,
The main elements embodied in the preferred form of machine the air
chamber A, ore bed B, vacuum chamber C, refuse chamber D, air box E, exhaust
fan F, and various adjuncts thereto; and the invention consists in certain combinations
of two or more of such elements and also in particular features of construction of
several of said elements, all as will hereinafter more fully appear.
I will now proceed to describe my invention more specifically and will first
indicate the preferred mechanical constructions and combinations of the parts and
their relative arrangement with the purposes thereof, and then the general operation
of the machine as a whole.
In the drawings, 1 indicates the sills, 2 the uprights, and 3 the cross timbers of
any suitable frame adapted to support the operative parts of the machine.
4 is a main or supply hopper which receives, from the sizing screen, the material
to be operated on, sail hopper having a suitable slide or gate 5.
Between the supply hopper 4, and the ore-bed B, is the feed hopper 6, preferably
arranged or formed in one end of the case 23 of vacuum chamber C, the wall 7 of
said feed hopper being of sheet metal having a flange 8 (see Figure 6) which
supports the free end of the cover 24 of the vacuum chamber C.
The bottom of this feed hopper 6 is controlled by a slide or feel gate 9,
adjustable by means of a screw rod 10 (see Figures 6, 9 and 10), or other suitable
device.
This feed hopper 6, as before specified, is preferably formed with the case of
vacuum chamber C and with said case, is detachable from the ore bed B on which
both rest see Figures 8, 9 and 10.
The slide-gate 9 however is preferably attached to the end or cross bar of the bed
frame 13 and has a peculiar construction which is more clearly shown in Figures 12
and 13, that is to say, the front of the slide gate 9 has a series of rectangular open
slots bordered by downwardly projecting flanges 12 (indicated by dotted lines
Figure 13) and shewn in full lines in Figure 12. By this construction the size of
the series of openings in the bottom of tho feed hopper 6, can be varied as required,
and at the same time the material is feed across the ore bed in an interrupted or
broken line (not continuously as heretofore) with intervals or air spaces which
permit the free passage of the air (see arrows Figure 12) and prevents the air
currents from interrupting and destroying the regularity and uniformity of the
feed.
B indicates the orc-bed which has its independent frame 13 arranged upon and
secured to, though detachable from, the horizontally vibrating frame 27 to which it
is usually secured by end wedge 14, (see Figures 1, 6 and 9).
The construction of ore-bed B will be best understood by comparing Figures 6, 9,
10, 14 and 15, and is as follows:
Any perforate metallic material (preferably steel wire netting) having openings
(or mesh) larger than the screen which has been used to sort or size the material
to be concentrated-is corrugated or bent to form a series of hills and valleys, or
alternate reverse inclines, and is then secured in the bed frame 13 in any suitable
manner.
In the case of wire netting, the inclines may be formed by letting into the side
bars of the frame 13, at suitable intervals, transverse metallic strips or bars 15,
(see Figures 6, 10, 14 and 15) over which the wire netting 16 is stretched, and then
drawn down into valleys by means of transverse wires 17 placed over the wire netting
at points between the supporting strips or bars 15, the ends of the wires 17 being
secured to the bed frame 13 as at 18 (Figures 9. 10 and the spring of the wires 17
being prevented by guy-wires 19 extending longitudinally of the bed frame as shown
in Figures 14 and 15.
For purposes of convenience in construction I sometimes prefer to construct the
bed frame 13 of two sections 13 13b, having serrated or zigzag intermatching side
bars (see Figures 1 and 6) the zigzag lines of separation corresponding to the hills
and valleys of the screen. If this construction is not adopted the side bars of
frame 13 should be recessed to receive the edges of the perforate material.

page_text: The rear end of the ore-bed (see Figures 6, 9 and 10) has a bridge piece or end
plate 20 upon which, by means of suitable set or thumb screws, is secured an
inclined adjustable plate 21 which projects over the end of the ore-bed, and back
of said adjustable plate 21, the cross piece 20 is slotted as at 22, to provide a
throat or exit for the debris or waste which pasacs off from the ore bed.
Within the case 23, or box which rests on the frame of the ore-bed, is suspended
the cover 24 of the vacuum chamber C, its free end resting on the flange 8 of hopper
wall 7, while its opposite end is adjustably suspended from a cross piece 25, of case 23,
by means of a threaded rod 26.
This cover 24 of the vacuum chamber C, is preferably of French plate glass
set in a suitable frame, as thereby the ore bed is rendered constantly open to
inspection.
The ore bed itself is covered by, or constituted of, a layer of shot, or equivalent
sized permeable mobile material.
The function of the corrugated perforated sheet or wire gauze bottom 16, with
its transverse hills and valleys, is to give to the shot, or other material constituting
the bed, a vertical jigging motion, while the reciprocation of the frame gives the same
a horizontal motion: the function of the adjustable cover 24 of the vacuum chamber
is to increase or decrease the velocity of the longitudinal air currents which pass
over the ore bed, and it will be at once apparent that as the cover 24 is raised by
the screw rod 26 to increase the angle between the bed and cover, as well as the
size of the vacuum chamber C, said air currents must decrease in velocity, while
when the cover is lowered the reverse must occur; the function of the adjustable
plate 21 at the end of the ore-bed, and extending over the same, is to increase or
decrease the depth of material retained on the bed accordingly as the character of
the material requires it to be treated in thick or in thin strata to be slowly or rapidly
worked off the bed-or whether a slow or a rapid discharge of the refuse is desired.
Immediately beneath the ore-bed B supporting and carrying the same, resting on
the spring supports 33 and refuse chamber D, is the horizontally vibrating or
reciprocating frame 27.
The two side pieces of frame 27 are connected at one end (see right hand Figure 6)
by a cross piece 28 having a transverse slot 29 corresponding with the slot 22 of the
ore-bed, and said piece is faced on its underside (see Figure 7) with a metallic
plate 30 (preferably brass) which moves over a suitable packing 31-preferably of
French felt applied to the top of refuse chamber D. At the opposite ends, the side
pieces of vibrating frame 27 are connected by a cross-piece 32 from which flexible
steel spring supports or straps 33 extend down to a cross piece on the sills of the
main frame, the straps 33 being bolted to both the cross piece 32 of the vibrating
frame 27 and the main frame. Arranged over, and bolted to, cross pieces 32 is a
second cross piece 34, from which flexible steel straps 35 extend to yokes 36 (Figure 8)
which encircle eccentrics or cams on the driving shaft 37 whereby the frame 27
together with the ore bed B is vibrated.
A indicates the air chamber, or chamber below the ore-bed, through which the air
enters the machine, and this chamber might also be called the concentrate chamber,
as it receives all the concentrates which pass through the ore-bed. This air chamber A
is formed with an inclined bottom 66 (see Figures 46 and 8) to discharge the
concentrates, and is divided up near its bottom into a series of separate shoots by
vertical partitions 38. In order to obtain free access to the air chamber A, one side
of said chamber may be partially closed by a detachable door or side piece 39 (see
Figure 1, 4 and 8) and the space above said door 39 through which the air enters
may be closed by a wire gauze screen.
In line with the air chamber A, and likewise below the ore-bed B, is the refuse
chamber D, whose bottom is double inclined or hopper-shaped and has arranged
therein a worm or screw conveyor 41 (see Figures 5 and 6) which discharges the
refuse through a port 42, in the side of chamber D into an overflow bar 43 of such
height as to keep the chamber. box D constantly closed or sealed, which is necessary,

page_text: because this chamber D, in the present application of the invention, is placed between
the ore-bed and exhaust fan F.
In the cover or top of refuse chamber D are two slots or ports, one of which 44,
establishes communication between vacuum chamber C (over the ore bed B) and the
other 45, establishes communication between the refuse chamber D and an air box E
interposed between the refuse chamber D and the exhaust fan F. This latter
port 45 may be provided with a valve 46 to control the size of or close the port 45
at will.
Located over the refuse box D, and communicating therewith, is the air box E,
having a tube or flue 47 (see Figures 3, 5 and 6) extending from the top thereof to
the eye of the fan F.
The air box E is provided with two ports, the first 47* for admitting at times a
continuous regulated volume of air to the air box E to controi the force of the
exhaust (or vacuum) exerted by the fan in vacuum chamber C, and through ore-bed B ;
the second 48 to intermittently, partially, or wholly, destroy the vacuum in the
vacuum chamber C, so that the machine can be made to operate as a gravity
concentrator, and a simple screen, alternately, that is to say, by the vacuum over, and
air jets through, the bed (when the port 48 is closed, and by simply screening when
the port 48 is open and the vacuum destroyed).
Port 47, which may extend nearly across the air box (see Figures 5 and 8) is
covered with wire gauze and silk netting, or any fine fabric may also be used to
cover the wire netting and temper the force of the air currents. With this port an
ordinary adjustable gate or slide valve 49 may be used.
Port 48, for the intermittent currents, requires to be of different construction,
because both the volume and frequency of the air admitted to destroy or trouble the
vacuum in vacuum chamber C, must be altered to suit different material; therefore
said port is formed by means of a transverse slot extending across the rear side of
the air box E (see Figure 3) in which are arranged slides 50 which may be moved
to or from each other to increase or diminish the size of port 48. In order to
close the port 48, a valve 51 is used, said valve being hinged on one side, as at 52,
and provided at the opposite side with springs 53 to draw the valve to its seat, and
having an adjustable tongue 54 which stands in the path of a tappet 55 on a rotating
shaft 56 by means of which said valve 51 may be intermittently opened.
equivalent of the valve shown and described would be any of the many well known
tappet or puppet valves.
The
A simple construction of the tappet 55 is shewn in Figure 11 which is made by
slotting the shaft 56 for the reception of an adjustable steel blade which can be
secured by a set screw 57.
It will be seen that by adjusting this blade so that the opposite tappets are of
equal length, a regular intermittent opening of the valve, twice at every revolution
of shaft 56, can be obtained, while by varying the length of the opposite tappets, in
the adjustment of the blade, the valve 51 may be held open longer at one time than
at the other, or may be entirely missed by one tappet, so as to be opened only once
in each revolution of the shaft 56. It will also be seen that by a proper manipulation
of the valve, and of ports 45, 47%, and 48, a great variety of changes may be had
in the operation of the machine so as to adapt it to treat an infinite variety and
character of material.
Within the air box E, and extending across the same over the port 45, and above
the botton of said air box, is a triangular baffle bar 65, to break up the direct air
current from refuse chamber D to fan F. Any suitable exhaust fan F may be
employed, the one chosen for purposes of illustration is the well known Sturtevant
Exhaust Fan, which need not be further described.
Of the devices described, certain parts require motion, viz.-the horizontally
vibrating frame 27, the conveyor 41, the valve 51, and the exhaust fan F, and for
such purpose any suitable gearing may be used.
In the drawings I have shown a main shaft 37, provided with a drum 57, which

page_text: receives the power belt, and which, through flexible steel straps 35, vibrate the
frame 27. This shaft 37, may have balance or fly wheels 58, and is provided with
two pulleys, one of which 59, through a belt 60, drives the fan F, while the other 61,
through a belt 62, drives the shaft 56 of the tappet 55, and the latter shaft in turn,
through a belt 63, drives the shaft of the conveyor 41. As the speed of the
tappet and the conveyor require to be altered from time to time, according to the
material operated on, cluster pullies have been shown for that purpose, but they,
and their equivalents, are so well understood that no description of them is
necessary.
The devices being of substantially the construction specified will operate as
follows. Power being applied to drive the exhaust fan F, vibrate the frame 27 and
the ore bed therein, and operate the tappet 55 and the conveyor 41-the valve 9 of
feed hopper 6 is set to give the desired feed of material to the ore-bed. The
material, owing to the specified construction of valve or slide 9, flows on the bed in
parallel streams which do not interrupt the flow of the air between the hopper 6
and the ore bed. On reaching the bed the material spreads out and flows thereover
in a regulated stratum where it is subjected to minute up-flowing jets of air which
enter the orc-bed from air chamber A and permeate the bed and the superimposed
stratum of material to be treated, permitting the concentrate to sink by gravity into
and through the bed, and fall into an air chamber A whence it escapes and is
collected, as before specified. The passage of the minute air jets into the vacuum
chamber, and thence over the ore-bed B through ports 22, 29, 44 into refuse
chamber D, causes the flow of the debris, waste, or refuse with it into said refuse chamber
wherein the heavier gritty matters are deposited by gravity to be gradually pushed
out of the chamber D into the overflow box 43, by conveyor 41, only the lighter and
harmless dust being permitted to enter the fan F.
The feed gate 9, vacuum chamber cover 24, plate 21, port 45, gate 49 of port 17*,
slides 50 of port 48, adjustable tongue 54, and tappet 55 on shaft. 56; operating
valve 51, having all been adjusted to adapt the machine to the size and character of
the material to be operated upon, the result will be as follows:-During the interval
that the valve 51 is closed, the upflowing jets of air through the ore bed B and
superimposed pulverised ore, have the effect of stratifying the mass with the heavier
or mineral particles at the bottom, and the lighter or gangue particles at the surface,
while the longitudinal flow of the air caused and regulated by the cover 24 carries
the surface of the mass (composed of gangue) towards the discharge end of the
chamber C, thus permitting a corresponding quantity of pulverized ore to enter
through the feed gate 9, but the moment the valve 51 is opened these conditions are
partially or wholly suspended-while the sifting is continuous, though less rapid,
while the stratification is taking place because at such time it is retarded by the
air flowing upward through the ore bed.
Having now particularly described and ascertained my invention, and in what
manner the same is to be performed I claim -
1. The construction and use of a dry concentrator for ores, consisting of a feed
hopper with adjustable feed apertures, a vibrating permeable ore bed having over
it an adjustable cover and having under it a discharge shoot for ore, and an inlet
for air, a refuse chamber with worm-conveyor and overflow chamber, an air-box
with an adjustable valve, and a puppet valve, and an exhaust fan, arranged and
operating substantially as described with reference to the accompanying drawings.
2. Making the vibrating ore bed with adjustable cover and with its perforated
or meshed bottom corrugated so as to give vertical and horizontal movements to
the shot or other small mobile bodies which are laid upon it and present instertices
for passage of air upwards and of ore downwards, substantially as described.
3. The refuse chamber having a downwardly directed inlet from the ore bed and
an upwardly directed adjustable outlet to the air box, a worm conveyor and an
overflow chamber substantially as described.

page_text: 4. The air box with baffle, with adjustable air inlet and with spring puppet valve
operated by tappet, substantially as described.
Dated this 24th day of June 1889.
ERNEST DE PASS, Fel. Inst. P.A.,
68, Fleet Street, London, Agent for the Applicant.