IMPROVEMENTS IN PNEUMATIC MACHINERY OR APPARATUS FOR THE SEPARATION OF MINERALS AND OTHER MATERIALS OF DIFFERENT DENSITIES."
Year: 1881

page_text: LETTERS PATENT to Benjamin Woolley Hart, of Kildare Terrace, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN PNEUMATIC
MACHINERY OR APPARATUS FOR THE SEPARATION OF MINERALS AND OTHER
MATERIALS OF DIFFERENT DENSITIES."
PROVISIONAL SPECIFICATION left by the said Benjamin Woolley Hart at
the Office of the Commissioners of Patents on the 15th November 1881.
BENJAMIN WOOLLEY HART, of Kildare Terrace, in the County of Middlesex.
"IMPROVEMENTS IN PNEUMATIC MACHINERY OR APPARATUS FOR THE SEPARATION
OF MINERALS AND OTHER MATERIALS OF DIFFERENT DENSITIES."
My Invention relates to machines or apparatus of the class described in the
Specification of my former Letters Patent, dated April 1, A.D. 1879, No. 1291,
which machines are commonly known as air jigs or pneumatic ore separators, and
are used for the separation of associated materials of different densities. The
machine or apparatus, as described in the said Specification, is constructed with a
peculiarly shaped box, which is widest at its rear or hopper end, its sides extending
froin this rear end parallel to each other for a short distance, and then converging
to the front of the box which is comparatively narrow. The said box is provided
with a sieve bed which forms an inclined plane from the back to the front of the
box. The admission of air to the space below the sieve bed is effected and
controlled by the aid of suitable valves which act to produce the puffs of air
required for jigging the material on the sieve bed.
According to my present Invention I modify the construction of the above
described apparatus as follows, that is to say:-
The box is shaped on its exterior sides, substantially as in my said former
apparatus, but instead of being open at the top, the said box is closed by a cover of
suitable thickness provided with apertures at the sides for the escape of the lighter
portions of the ore or other material, and there is an aperture at the lower or small
end of the said box for the discharge of the dense or heavy portions from the sieve
Price Gd 1

page_text: bed. By thus covering the box or bed the air forced through the sieve bed or
bottom is to a certain extent confined, so that its pressure is exerted more
advantageously than heretofore in separating the ores or other materials on the
sieve bed according to their specific gravity.
I further modify the said apparatus by diminishing the space below the sieve
bed. For this purpose I construct the portion of the box below the sieve bed with
only a narrow passage or space for the air immediately under the bed, and
extending from the hopper end to the discharge end of the box. I may accomplish
this result by placing in the central portion of the part below the sieve bed a block
of wood or other suitable material, of such dimensions as to fill the said space with
the exception of the aforesaid narrow air passage; and I prefer also to form an air
channel from the rear to the front of the box below the said block.
According to another part of my Invention the central portion of this block is
nised by a platform or cushion placed thereon to the level of the sieve bed, thus
dividing into two parts the passage or space for the air between the sieve bed and
the block.
The cover of the box is supported on the raised platform or cushion.
The under part of the cover is made hollow on each side, forming two troughs
convergent at the lower or discharge end of the box.
Another part of my present Invention consists in the division of the said troughs
transversely into a series of covered cells or compartments provided with apertures
at the outer sides for tho escape of the lighter portions of the ore or other material,
and communicating with each other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Benjamin Woolley Hart in the Great Seal Patent Office on the
13th May 1882.
BENJAMIN WOOLLEY HART, of Kildare Terrace, in the County of Middlesex.
"IMPROVEMENTS IN PNEUMATIC MACHINERY OR APPARATUS FOR THE SEPARATION
OF MINERALS AND OTHER MATERIALS OF DIFFERENT DENSITIES."
My Invention relates to machines or apparatus of the class described in the
Specification of my former Letters Patent, dated April 1, A.D. 1879, No. 1291,
which machines are commonly known as air jigs or pneumatic ore separators, and
are employed for the separation of associated materials of different densities.
and
The said Invention is illustrated in the accompanying Drawings, in which,-
Figure 1 is a central vertical section of a machine embodying my improvements;
Figure 2 is a transverse vertical section of portions of the same on the line x, x,
Figure 1.
Figure 3 is a plan of the said machine with the cover and sieve bed removed.
Figure 4 is a plan or top view; and
Figure 5, an underside view of the said cover.
Figure 6 is a vertical section of the said cover on the line y, y, Figure 4, looking
in the direction of the arrow.
Like letters indicate the same parts throughout the Drawings.
a represents the main frame of the machine, and b is the box supported
thereon. This box, as in the machine or apparatus described in the said former
Specification, is widest at its rear end or part adjacent to the hopper c, and its
sides b' converge from this rear end to the front of the box, which is comparatively
narrow, as shewn in Figure 3. The said box is provided with a sieve-bed d
which preferably consists of wire gauze, and which forms an inclined plane from
the back to the front of the box. The admission of air to the space below
this sieve-bed may be effected and controlled by the aid of suitable valves, which
act to regulate the pressure of air required for jigging the material on the said
sieve-bed. I prefer to use a "Root's blower" for compressing the air in my improved
machine, for the reason that such a blower produces intermittent currents.
At
According to my present Invention, instead of leaving the box open at the top,
as described in my said former apparatus, the said box is closed by a cover c.
the sides the said cover may be cut away or formed with openings of suitable
dimensions to permit the discharge over the box sides b' of the lighter portions of
the crushed or stamped mineral or other material under treatment. One or more
apertures at b* of suitable dimensions are provided at the front or small end of the
said box for the discharge of the denser or heavier portions from the sieve-bed d.
By thus covering the said sieve-bed the air forced through the same is to a certain
extent confined, so that its pressure is exerted more advantageously than heretofore
in separating the minerals or other materials on the sieve-bed, according to their
specific gravity or density.
I further modify the said apparatus by diminishing the air-space below the sieve-
bed. For this purpose I may so construct the portion of the box below the said
sieve-bed that there will be only a narrow passage or space for the admission of air
immediately under the bed, and extending from the hopper end to the discharge or
small end of the box; or I may accomplish this result by placing in the box ba
block of wood or other suitable material, whose central portion f¹ extends
upward into contact with the sieve bed d, leaving on either side a passage g for
the air beneath the sieve-bed. In other words, the elevated portion f' of the said

page_text: block divides into the two parts g, g, the air passage or space between the sieve-
bed and the said block f. h represents an air channel, which may be formed in the
lower surface of the block f from the rear to the front of the box to provide for the
passage of air directly to the front or narrow end of the said box.
The cover c of the box is supported upon the central raised portion f¹ of the
block f. The thickness or depth of this cover is less at the two sides than at the
central part e¹, so that two converging channels or troughs i, i, corresponding in
position with the aforesaid air spaces are formed at the sides of the box for the
downward passage of the mineral or material under treatment, the lighter grains of
which travel downward in these passages till they escape therefrom at a higher or
lower position by the side openings hereinafter described, according to their size,
while the heavier or denser grains pass onward to the discharge opening or openings
at the front of the box, being thus separated from the lighter portions or grains
according to their specific gravity. The downward movement of the lighter
portions of the material under treatment, a greater or less distance according to
size, obviates the necessity for employing auxiliary machinery, such as that known
as sizing machinery, and heretofore generally recognized as indispensable in the
treatment of minerals whereof the grains differ in size as well as in specific
gravity.
The under surface of the cover which constitutes the upper side of the said
channels is constructed, as shown most clearly in Figure 6 of the Drawings, that is
to say, it is formed with a series of cells or compartments j closed at their ends
nearest the centre of the cover c by the sides of the part e', but open or provided
with openings at their outer sides to permit the discharge of the lighter portions
of the mineral or other material over the sides of the box b. The said cells or
compartments, which diminish in width from the rear-to-the-front-of-the-machine,
cominunicate with each other, and are preferably formed with an inclined upper
surface, as shown. The said cells may however have their upper surface parallel
with their under surface if desired. By thus forming the cover with cells or com-
partments I provide for arresting or retarding the downward flow of the lighter
mineral or other material, so that it will more readily escape at the sides of the
box by the aforesaid openings. In the Drawings I have shown the cover c
constructed in two parts, but it will be obvious that the said cover may be formed
in one piece.
,, represent small plates or stops, which form partitions or divisions in the
openings between the sides of the box and the sides of the cover, so as to further
check the downward flow of the lighter particles of the nineral or other material
along the said openings, and thereby increase their tendency to escape over the
sides of the box. Between the lower edge of each of these stops and the sieve-bed
there is a space, as shown in Figure 2, to permit the continuous downward flow of
the heavier material upon the said bed.
To equalize the distribution of the air passing from the air chest / to the sieve
bed, I in some cases prefer to cause it to pass through a perforated plate, as shown
at m, Figure 1.
In some cases I secure to the front or discharge end of the box b an inclined
discharge spout or chute for conducting the mineral or other material to any
suitable receptacle. This spout I preferably provide with a valve, so that the
discharge of the material may be increased or diminished, or entirely stopped.
Having thus fully described my said Invention, and the manner of performing
the saine, I wish it understood that I do not restrict myself to a box or apparatus
of the shape shewn in the accompanying Drawings, nor to the combination of the
cover with a box which has converging sides, or which has channels or troughs
separated from each other by a central block or partition, nor do I now claim the
construction of a box with a sieve-bed and converging sides; but I claim,-
First. The employment of a covered sieve-bed with suitable discharge apertures
for the separation of materials of different densities by the action of compressed air,
as above specified.

page_text: Second. A machine or apparatus provided with a sieve bed for the separation of
materials of different densities by compressed air, and constructed with converging
sides enclosing covered passages separated by a central portion or partition, which
passages are so formed that the separation of the materials is effected as they travel
forward on the sieve bed in the manner above specified.
Third. The combination with the box and the sieve-bed of the block provided
with the central raised portion ƒ¹, substantially as above set forth and for the purpose
specified.
Fourth. The cover constructed and arranged substantially as herein set forth for
the purposes specified.
Fifth. A machine or apparatus for the separation of minerals and other materials
of different densities, consisting of the parts constructed and combined, substantially
as shewn in the Drawings, and operating in the manner herein set forth.
In witness whereof, I, the said Benjamin Woolley Hart, have hereunto set my
hand and seal, this Eleventh day of May, in the year of our Lord One
thousand eight hundred and eighty two.
B. W. HART. (L.S.)