Year: 1888

page_text: Date of Application, 24th July, 1888
Specification Accepted, 24th Aug., 1888
I, ALVAN PERRY GRANGER, of the City of Denver, State of Colorado, United
States of America, Inventor, 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 relates to pneumatic ore separators or that class of machines in which
a current of air is employed in conjunction with mechanical devices to effect the
separation of the gangue from the mineral or mineral-bearing rock. The invention
relates more particularly to the precipitator or board on which the material to he
separated is agitated and from which the gangue is drawn by the air current; to the
combination with the board of a dressing-plate; to devices concerned in the control
of the air current; to the passages for the air current; to the adjusting devices; to
features of construction by which the effects of adjustment are more readily observed by
the operator to the construction of the sizing screen, when the machine is a serial
one, in which different sizes are operated upon in the different sections of the machine,
and to other matters as will be hereinafter explained. The nature of my improvements
will be fully understood from the following description of the accompanying drawings
which illustrate a serial form of machine.
In said drawings,
Figure 1 is a front side elevation of a serial dry ore separator adapted for grading
or sizing the ore and concentrating the several grades separately, parts being broken
away for better illustration.
Figure 2 is an end view of the machine looking towards the left of Figure 1.
Figure 3 is a transverse, vertical section in the line x-x of Figure 1.
Figure 4 is a fragmentary, horizontal section taken above the dressing plate and
eccentric shaft or in the line x-x of Figure 5.
Figure 5 is a vertical section of a single division of the machine taken in the
indirect line x-x of Figure 3.
Figure 6 is a fragmentary detail of which the front section is in the line y-y of
Figure 3.
Figure 7 is a fragmentary, perspective, rear view showing the connection of the
suction fans with the housing of the machine.
Figure 8 is a broken part of a feed roller showing a practicable arrangement of
recesses therein.

page_text: Figure 9 is a fragmentary, rear elevation broken away to reveal the recessed food
roller in place and showing other details.
Figure 10 is a plan view of one form of the curbed opening of the precipitator
enlarged.
A A are frame uprights; B B are transverse partitions; CO are vertical walls or
housings attached to the frame; C is an inclined board forming the bottom of a
hopper C from which the ore is delivered to the concentrating devices; C³ is an
inclined board upon which falls the gangue from the concentrating devices; is
another inclined board beneath the board Cs and forming with the latter an inclined
air passage which is downwardly prolonged from its upper end into communication
with the suction fan D; E is a nearly horizontal precipitator placed between the
hopper and the cantboard 03; F is a "dressing plate" placed over the precipitator;
G is a yoke formed lever pivoted to the frame uprights for regulating the vertical
position of the foot of the precipitator; H is an inclined, rotating shaft on which are
secured a succession of ore grading, tubular screens; II are the several screens
referred to JJ are imperforate shells surrounding the screens and K is the drive
shaft located across the foot of the machine and provided with fast and loose pulleys
K' K2 and a bevelled friction wheel K which engages with a similar wheel L' on the
longitudinal, eccentric shaft L. M is a horizontal shaft mounted across the foot of
the machine for rotating the screen, for which purpose it is driven by a belt m from the
shaft K and is provided with a pinion which meshes with the wheel H¹ on
the shaft H. N is a feed shaft or roll arranged to allow the passage of material from
the hopper C to the head of the precipitator while at the same time preventing any
considerable passage of air along with the said material to be screened, said roll being
shown as driven by a belt n from the screen shaft H at the head of the machine. The
fans D, one for each compartment or division of the machine, are mounted on a
longitudinal shaft D₁ and are driven by a belt or belts d from the eccentric shaft L.
Over the inclined series of screens 11 is a housing O and at the head of the series of
screens is a feed hopper P which delivers into the first screen of the series through a
hollow trunnion H2 on the end of the screen shaft, which trunnion has lateral openings
h within the said first screen of the series.
The illustrated rotary, serial screen mechanism for sizing the ore is constructed to
deliver the largest size of ore at the head of the machine and the smaller sizes
successively toward the foot of the machine. This sizing mechanism consists of a
series of conical screens II mounted on the same inclined shaft and having their
larger ends towards the head of the machine. They are made of slotted metal held
concentric with the shaft H by circular end boards h¹. These boards close the
lower ends of the several screens I preventing the passage of material over their tails.
External to each screen I and concentric therewith is secured, in any suitable way, an
imperforate, tubular, metal shell J which is arranged at its foot to discharge directly
into the next screen I of the series past the margin of the adjacent board /. At the
foot of each screen I the latter is provided with a series of lateral openings from
which lead tubes h³ through the shell J in position to discharge the contents of the
screen from which they lead, into the subjacent hopper C². The material which
passes through the slots (or other form of screening passages) in the screen falls upon
the surrounding shell J and passes on from said shell between the tubes into the
next screen I. Correctly speaking therefore, the material which rides over the
screen instead of that which passes through it is that part of the ore which each
screen delivers into the hopper beneath it. No screen is present in the last com-
partment of the machine, but the shell J about the next preceding screen is prolonged
to deliver into said last compartment or hopper, as sufficiently indicated by dotted
lines in Figure 1.
Any other suitable screening device, sizing mechanism or means for feeding the ore
through the several divisions of a serial machine may be employed in place of that
above described without departing from my invention as concerned in the con-
structions hereinafter set forth.
The bottom board C₁ of the hopper C declines from the front to. the rear of the

page_text: machine and the frame is open beneath said bottom board, as shown in Figures 2 and 3.
The converging walls of the hopper C² in each machine or division of a serial machine
only proximate, as shown in Figure 3, and in the delivery opening thus formed is
arranged suitable means for permitting a regular passage of ore downwardly while
proventing any considerable current of air to be created through the same passage
by the action of the fans to be hereafter referred to. In the present instance such
means is shown to consist of a continuons, rotating feed roll N which makes a close
joint with both the edge of the board C' and the terminal bar or cleat c of the outer
housing C. If said roll be of unyielding or incompressible material, as wood, for
example, it will, as shown, be peripherally recessed, as by holes n' bored radially
therein, into which the ore drops from the hopper and which discharge successively as
the roll is rotated on its axis. This roll, may, however, be made of rubber or provided
with a rubber or other compressible covering which will allow the ore to pass beneath
the roll as the latter is rotated, the compression produced by the passing ore answering
to the holes n' illustrated in the unyielding form of roll shown in the drawing.
Beneath the feed roll N is located the rear end or head of a precipitator E which has a
rapid reciprocatory or vibrating motion in a direction from front to rear of the machine.
To facilitate this rapid motion and at the same time to practically cut off the admission of
air at the head of the precipitator said head of the precipitator is suspended from the
cleate by a sheet of metal e external to the feed roll N, so that the material delivered by
the latter falls properly upon the precipitator. At its front end or foot the precipitator is
supported by a similar sheet of metal el fastened at its upper edge to a transverse
cleate on the under side of the precipitator, and at its lower edge to a cleat or bar e³.
Said bar is in length only equal to the width of one division of the machine and is
vertically movable to afford vertical adjustment of the foot of the precipitator. This
adjustment is effected at will by means of two connected levers G, one for each side of
the precipitator, pivoted to the proximate faces of the adjacent frame uprights A, the
levers being connected together in order that both shall move in harmony and hold
the movable end of the precipitator level transversely. As an additional improvement
the levers G are made of a single piece of flat bar iron bent to horseshoe form and
having their curved connection directed inwardly beneath the hopper C³ so as to be
out of the way of disturbance when once set, as well as in favorable position for
manipulation when required to be moved. Incidentally the levers in this position may
balance the precipitator but they are held sufficiently by the threaded bolts g' which
form their pivots or they may be otherwise held in their set position. The free ends
of the levers G connect by vertical rods y with opposite ends of the bars and rise
past the edges of the precipitator, as seen in Figures 2, 4 and 6, so that the latter can
be freely vibrated between them. The construction of the precipitator as here shown
and as particularly claimed as a distinct improvement will be hereinafter described.
For the purposes of the claims herein made which do not specify the distinctly novel
form of the precipitator it is to be understood that the said claims are not restricted
to that form.
Over each precipitator is placed a plate F, here called a (dressing-plate" because
it is concerned in controlling the air current by which the dressing is performed on
the precipitator. This plate F may be of any suitable material, but, as a separate
improvement it is described as consisting, in part at least, of glass in order to afford a
view of the material upon the precipitator while the machine is at work. As here
shown the dressing-plate is partly of glass and partly of wood, F1 F1 being opposite
side bars supporting a glass portion F of the dressing-plate by means of sheet metal
strips (Figures 5 and 6) and F³ being a wooden part of the plate at its rear margin
which connects the opposite side bars F¹. At their rear ends the side bars F¹ are
prolonged in their upper portions, as seen at f1 (Figures 3 and 4), and these prolonged
ends rest on pins or other suitable supports f² near the point of suspension of the
precipitator beneath the plate F, in order that in the adjustment of these parts at their
opposite ends their movements may be made from practically coincident centres of
motion. Both the precipitator and the superposed dressing plate are retained
laterally in place by the frame uprights and partitions B the lateral space between

page_text: which they loosely fill. The precipitator is, however, provided with side cleats e
which form marginal walls therefor and which riso into rabbets f³ in the outer
and under faces of the bars F¹, as more clearly seen in Figures 5 and 6. The front
ends of the plates F are severally adjustable vertically, either with the subjacent
precipitators or independently of the latter, by means of screw-threaded nuts f
(Figure 6) on the rods g and brackets attached to the side bars F¹ and resting
on the nuts f. These brackets are preferably slotted or otherwise arranged to
bear on the rear faces of the rods g in order to prevent forward movement of
the plates F. At their rear ends said plates F have attached to them vertical
spring plates of sheet metal the upper edges of which bear against the bottom
board of the hopper C in front of the feed roll N so as to close off the ingress of
air at this point. From a point closely adjacent to the under surface of the head of
each precipitator E the board C³ declines forwardly reaching from one partition
wall B to the opposite one, and at its lower edge said board is provided with a hinged
flap valve c' extending preferably entirely across the compartment. This valve cis
raised and lowered to regulate the extent of its opening by suitable means, as, for
example, a corde which passes out through a hole of the housing and is wound up on
a screw or pin c³ to hold the valve in a required position.
Each compartment of a serial machine is provided with a separate suction fan Dand
the fans are shown to be of different capacities or powers, the stronger being located
at or near the head of the machine and the weaker towards and at the foot of the
machine. The different capacities of the fans are indicated in the drawings by their
differing width, in dotted lines of Figure 1. The air passages C leading to the fans D
accumulate the gangue which falls from the cant-board e until the amount overcomes
the suction and forces the flap valve c* in the usual manner of such devices.
So.
Returning to the precipitator E 1 remark, first, that it may, for the general purposes
of my invention, be in its details of different construction from that here described.
The improved form and construction herein shown and claimed as a separate
improvement is substantially as follows:-In general the precipitator is a board E
having a number of holes e through it, downwardly through which holes the
particles of gangue are drawn from the surface of the mass of material on said board.
These particles of gangue are brought to the surface of the ore mass on the board by
the rapid reciprocation of the latter by short strokes in its own plane, or substantially
This reciprocation is produced by a short-throw eccentric on the shaft L,
preferably opposite the middle of the precipitator board, and a suitable eccentric strap
or its equivalent which communicates the throw of the eccentric to the board E.
The holes e are more numerous in the board at the head thereof than in that at the
foot of the serial machine and their number is graduated in these and the intermediate
boards proportionately to the relative force or quantity of air required to accomplish
the work of dressing. Each hole e' is surrounded by a curb e' which projects a short
distance above the surface of the board and, as a further improvement, said curbs are
oblong and diamond shape in plan view, as seen in Figures 4 and 10, to facilitate the
passage of the ore about them. The construction adopted as most convenient, is to
make the holes themselves diamond shaped and to force the two bent or curved
plates e into the holes, to form the said curbs and side walls thereof. These apertures e
are also desirably arranged in alternation with each other, as seen in Figure 4.
In the construction here shown, the board E (say 3 feet and 6 inches or 4 feet long
from head to foot and 20 to 22 inches wide) has a plain, flat unapertured part eat its
head or rear end extending a distance of say 12 inches. The apertured part e comes
next, extending say 12 or 15 inches. Next follows an unapertured portion eo which
has a transverse depression presenting, first, a longitudinal declivity ell extending
say 3 inches and dropping the surface of the board about one-eighth or three-
sixteenths of an inch at its lowest point. From this lowest point the surface rises
longitudinally to the board to about its original plane by an ascent extending say 15
or 16 inches. The object of the depression mentioned is to provide for the accumu-
lation of a mineral bed" over or upon which the air dressing is effected. The
declivity for said bed may, if desired, extend above the lower line of curbed

page_text: apertures eº or as far back toward the rear end of the precipitator as may be thought
best. The entire surface of the board E is covered with a coat of corundum, secured
by means of shellac or otherwise, for the purpose of giving a durable rough surface
which facilitates precipitation. The board or precipitator is slightly and adjustably
inclined downwardly from head to foot so that in the constant vibration of the board
the ore slowly passes forward thereon. The ore received at the head of the precipitator
is, by the shaking action, uniformly spread or distributed upon the plain or un-
apertured part e of the board, and owing to the same fact of shaking the precipitation
of the mineral to the bottom and the ascent of the gangue to or towards the surface of
the mass, at once begins and continues during the passage of the ore over the board.
The air drawn inward by the suction fan D finds ingress to the space between the
precipitator and the dressing plate F only at the foot of the precipitator and it
consequently passes up along the surface of the ore on the board E till it reaches the
holes through which it passes downwardly to the fan. In this movement of the air
over the precipitator it picks up the particles of gangue which have risen to the
surface of the mass of ore thereon and removes them through the holes whence they
fall upon the inclined board C³ and move with the air current through the adjustable
valve c¹. Beyond this valve the air is deflected backwardly and upwardly through
the passage C, the lower end of which is purposely made wider, as shown, in order to
lessen the suspensive force of the air current at this point and thereby release the
gangue, which finds escape through the valve c*.
In the operation of the mineral bed formed in the depression of the precipitator the
dressing action is performed exclusively upon the surface of the mass, the gangue
being withdrawn from the top, as described, and the mineral being delivered over the
foot of the board into any suitable receptacle, not shown. In this forward movement
of the mineral the bed is being constantly changed and renewed and never becomes
exhausted or impaired.
The inclination of the precipitator will be generally or invariably greater than the
acclivity leading from the bottom of the depression to the foot of the board in order
that the desired forward movement of the ore and minerál may take place in
opposition to the force of the oppositively moving air current. The force of the air
draft will be of itself adjusted by the valve c¹ but with a given air draft the movement
of the ore upon the precipitator will be regulated by adjustment of the inclination of
the latter. The dressing plate will commonly stand at its lower end about seven-
eighths of an inch from the surface of the precipitator, but at the head of the
precipitator it will usually stand about five-sixteenths of an inch distant therefrom.
The inclination of the precipitator and that of the superposed dressing plate, one or
both, will be varied by the adjusting devices hereinbefore described in regulation of
the air current and the transparent part of the dressing plate enables the operator to
watch the action going on upon the precipitator and to thereby avoid loss of mineral
or imperfect concentration through the better adjustment of the tension of the air
current which he is able to effect by such observation while making the adjustment
and when the machine is in operation.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :--
1 The combination, in a rotary ore sizing mechanism, of a series of conical screens
mounted on a single inclined axis and arranged with their larger ends towards the
more elevated end of the axis, a series of imperforate, rotating, tubular shells severally
surrounding and concentric with said screens, the lower end of each shell being arranged
in line with the succeeding screen whereby it may discharge directly into said screen,
a head closing the lower end of each screen and a series of tubular passages leading
laterally from the foot of each screen through the surrounding shell, substantially as
described.
2: The combination, in a pneumatic ore separator, of a vibratory precipitator
having curbed apertures, a dressing plate supported over the precipitator with an air
passage between them which is open at their feet, a suction fan communicating with

page_text: said space through the apertures of the precipitator, a feed passage for the ore delivering
upon the head of the precipitator, and a feed regulator applied to said passage adapted
to restrain the admission of air with the ore, substantially as described.
3-A vibratory precipitator having apertures provided with projecting curbs and
having a depression or depressions in its surface for the formation of a mineral bed
thereon, substantially as described.
4: The combination of an apertured, inclined and reciprocating precipitator having
its angle of inclination adjustable about an axis at its head, a dressing plate arranged
over the precipitator and also adjustable as to its inclination about an axis near that
of the precipitator, and a suction fan in communication with the space between the
precipitator and the dressing plate, through the apertures in the precipitator,
substantially as described.
5: The combination of an apertured, inclined and reciprocating precipitator having
its angle of inclination adjustable about an axis at its head, a dressing plate supported
on an axis near that of the precipitator, devices for adjusting the precipitator and the
dressing plate, both together and independently, and a suction fan communicating with
the space between the precipitator and dressing plate through the apertures in the
precipitator, substantially as described.
6-The combination of an inclined, reciprocating precipitator provided with curbed
apertures and with a depression for the formation of a mineral bed thereon, a dressing
plate supported above the precipitator and a suction fan communicating with the space
between the precipitator and dressing plate through the holes in the precipitator, sub-
stantially as described.
7: A precipitator for ore separators provided with apertures having curbs which
entirely surround said apertures and which converge at acute angles at their ends and
which have their greater length in the direction in which the material to be separated
moves over the precipitator, substantially as described.
8: The combination with an adjustable precipitator, of joined levers connected with
the opposite sides of the precipitator whereby both sides of the precipitator may be
simultaneously and equally adjusted, substantially as described.
9: The combination, of a precipitator, a superposed dressing-plate, a transverse,
vertically movable bar and flexible plate supporting the foot of the precipitator, and a
lever connected with the transverse bar and having adjustable engagement with the
dressing plate, substantially as described.
10: The combination of a precipitator, an enclosed space having an inclined bottom
board beneath the precipitator provided with a discharge passage at its lower margin,
an upwardly inclined air passage beneath said board provided with an outwardly
opening valve at its lower end, and a suction fan communicating with the upper end
of said air passage, substantially as described.
11 The combination with a frame, a supply hopper and a precipitator beneath
the hopper (an open space being provided within the frame between the hopper and
precipitator) of a transparent dressing plate over the precipitator, and devices for
regulating the precipitator, located at the open side of the machine whereby the effects
of adjustment may be observed while being made, substantially as described.
Dated 2nd day of October 1887
ALVAN PERRY GRANGER.
Haseltine, Lake & Co.,
45, Southampton Buildings,
London, W.C.,
Agents for the Aunlicant.
ALVAN PERRY GRANGER.
Haseltine, Lake & Co.,
45, Southampton Buildings,
London, W.C.,
Agents for the Aunlicant.