SUCTION DISCHARGE FOR PARTICLE SORTER

DECHARGE DE PARTICULES PAR ASPIRATION

English Abstract

ABSTRACT OF THE DISCLOSURE
THIS INVENTION provides a concentrating method and apparatus
for use on particulate material. The method comprises feeding
a thin stream of the material past at least one suction nozzle
and removing selected particles of the stream by rapidly
applying a suction to the suction nozzle by injecting a first
burst of gas into a suitable venturi within the nozzle.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A concentrating method comprising:
feeding a thin stream of particulate material past
at least one suction nozzle; and
removing selected particles of the stream by
rapidly applying a suction to the suction nozzle by inject-
ing a first burst of gas into a suitable venturi in the
suction nozzle.
2. A method as claimed in claim 1 in which the stream
is supported on a perforated belt.
3. A method as claimed in claim 2 in which the
removal of the selected particles is assisted by a second
burst of gas directed through the belt into the suction
nozzle substantially simultaneously with the first burst of
gas.
4. A method as claimed in claim 1 in which the stream
is concentrated at least twice by passing it past at least
two suction nozzles in series.
5. Apparatus for removing selected particles from a
stream of particulate material, comprising:
a suction nozzle adapted to be located adjacent
to a stream of particulate material;
a venturi connected to the suction nozzle;
means for injecting a burst of gas into the venturi
to create a suction in the suction nozzle to suck particulate
material from said stream; and
a detection device operably connected to said
injecting means, said detection device including means for
detecting particles having a predetermined characteristic
and means for activating said injecting means when said
particles are adjacent to the suction nozzle.
6. Apparatus as claimed in claim 5 which includes a
compressed gas nozzle spaced from but directed into the
suction nozzle, the compressed gas nozzle being adapted to
be located below a mesh belt carrying the stream of particulate
material.
7. Concentrating apparatus including at least one

apparatus as claimed in claim 5.
8. Concentrating apparatus including at least one
apparatus as claimed in claim 6.
9. Concentrating apparatus as claimed in claim 7 or
8 for use in diamond recovery and utilizing x-ray irradiation
techniques for detecting diamonds.

Description

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THIS I~EI'~TION relates to a concentrating ~ethod and
apparatus of the type wherein selected particles of a stream of
particulate feed material are removed therefrom to provide a
concentrate and a tails fraction.
Such an apparatus has been used in the recovery of
diamonds from a particulate mater;al. The apparatus comprises
a mov-ing, endless belt on which a stream of material may be
supported. I~hen a diamond is detected, using x-ray fluorescent
techniques for example, a suction nozzle is operated to remove
the diamond and some nf the surrounding material from the stream.
In this way a concentrate is provided which may be ~urther
treated to ~ive a final product consisting of diamonds only.
An object of this invention is to provide an improved
method and apparatus suitable for diamond recovery as described
above. It should, however, be noted that while the description
in this specification is directed towards diamond recovery, this
should not be considered as a restriction to the invention which
may find a wide variety of applications.
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According to the invention a concentrating method
comprises:- ~
feeding a thin stream of particulate material past
at least one suction nozzle; and
removing selected parti-cles of the stream by rapidly
applying a suction to the suction nozzle by injecting a first
burst of gas into a suitable venturi in the suction nozzle.
Further according to the invention thE stream is
supported on a perforated belt and the removal of the selected
particles is assisted by a second burst of gas directed through
the belt into the suction nozzle substantially simultaneously
with the first burst of gas.
Further according to the ;nvention the stream is con-
centrated at least twice by passiny it past at least two suction
nozzles in series.
According to another aspect oF the invention ap~aratus
for removing selected particles From a stream of particulate
material comprises a suction nozzle connected to a Yenturi and
means for injecting a burst of gas ;nto the venturi to create a
suction in the suction nozzle.
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Further according to this aspect oF the invention the
apparatus includes a compressed gas nozzle spaced from buk
directed into the suction nozzle, the compressed gas nozzle
being adapted to be located below a mesh belt carrying the stream
of particulate materiali and the gas is compressed air.
The invention also provides for concentrating apparatus
including the apparatus as defined above, and particularly but not
exclusively diamond concentrating apparatus utilizing x-ray techniques
for detecting diamond particles.
lo - An embodiment of the invention, described by way of
! example only, follows with reference to the accompanying drawings
in which:-
Figure 1 shows in elevation an apparatus for
concentra~.ing diamondi~erous materiali and
Figure 2 shows a suction nozzle of the invention.
In this embodiment of the invention a method oF and
apparatus for concentrating diamondiferous particulate material
using kno~t~n x-ray techn;ques is provided. The method will then
become apparent when the use of ~he apparatus is discussed.
An endless mesh belt 1 about l5 centimetres wide is
supported by front and rear rollers numbered 2 and 3 respectlYely.
Diamondiferous particulate material is fed onto the helt by means
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of a sui-table hopper 4 at a position adjacent the rear roller
such that the material and the belt move in direction x at a
speed of about two metres per second.
The belt and material moYe consecutively under two
sets of similar apparatus each comprising known x-ray irradia-
tion and fluorescent detection units numbered 5 ~nd 6 respect-
ively. Immediately after each detection unit is apparatus 7
for removing a diamon.i which has been detected as well as some
of the surrounding gangue material.
Each of these apparatuses 7 comprises an elongated
suction n,ozzle 8 of rectangular cross-section spaced a small
distance above the belt and connected to a concentrate container
(not shown). A small distance from the orifice of the suction
nozzle is a c~mpressed air-operated venturi 9 which is controllc~
by a suitable fast acting valve 10. This venturi is adapted to
create a low pressure and hence a suction at the orifice of the
suction nozzle.
Below the mesh belt, directed therethrough and into the
suction nozzle, is a compressed air nozzle 11 connected via a
second fast acting valve to a source of compressed air.
Both of the compressed air valves are operated simultan- ,
eously by the x-ray fluorescent detection circuit. The compressed
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air nozzle blows a short burst of air throllgh the mesh belt to
decrease the efFective weight of the particles on that portion
of the belt. These particles are picked up by the suction in
the suction nozzle created by a burst of compressed air passing
through the venturi. Once the particles have moved past the
venturi they are subjected to a positive air pressure and air
current which carries -them into the concentrate container. The
bursts of compressed air are of about 5 milliseconds in duration.
As there are two sets of appara-tus the particulate
stream is subiected to the concentration process twice thus pro
viding a primary and a secondary concentrate.
The use of the compressed air nozzles is not essential
but enables the apparatus to operate on heavier particles than is
the case if they are -not present. It is to be appreciated that
1~ the burst of air from these nozzles has a maximum effect on the
particles at the position furthest removed from the suction nozzle
where the effect of the suction created by the venturi is at a
minimunl. Pre~erably the pressure of the air should not be
sufficient to result in a large amount of water from the wet feed
material bein~ injected into the suction nozzle.
Experimental results indicate that the method and
apparatus work with any particle sizes up to 10 millimetres.

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This invention may be used in conjunction with
a small but continuous suction to be applied to the suction
nozzle and for this to be supplemented by the venturi-
created suction described above.
Other embodiments and methods are envisaged
within the scope of the invention including its application
to other particulate materials and detecting devices.
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