Note: Descriptions are shown in the official language in which they were submitted.
25 The Prior Art
Heavy media separation generally involves the
immersion of a raw product in a fairly quiescent fluid
having a density intermediate between the densities of
WO 94114541 ' PCTIBE93100081:.~~~.
G
the two fractions to be separated. wen though heavy
media vessels come in many sizes shapes and capacities, ,
the basic principle cf separation remains the same upon
immersions into the separatory fluid, the less dense
fraction floats whereas the more dense fractions sinks.
Barrels, cones, cylinders and rectangular bath have all
served as heavy media separatory vessels. However, the
most common vessel shape within heavy media separatior_
is that of a horizontal scrolled barrel.
~0 uS 4,234,415 discloses an apparatus for separating
mixed solids of different specific gravid es by means of
a liquid medium. The apparatus comprises a barrel in
the form of a cone and which is not scrolled where the
separation takes place.
15 Solid particles are removed from said barrel by
means of a cone provided with scrolls linked together,
said cone acting in no way as system for separating
solids. In said apparatus, medium flows substantially
only through the opening having the minimum cross-
20 section of the cone wherein the separation takes place,
whereby the velocity cf medium increases from the inlet
of medium and solids to be separated towards said
opening.
Such an increase of velocity means that heavy solid
25 particles are able to flow together wit?: the float
through said opening.
Moreover, due to the lack of scrclls in the
separating cone, float particles remains embedded with
sink particles so that some float particles are removed
~0 tocrether with the sink fraction or particles.
There are also no disclosure cf a cur rain in the
separation barrel, curtain preventing float particles
Trom crossing into the sink evacuation cone or barrel.
Scrolled barrels may be generally classified as
35 mono- or bi-directional. Mono-directional barrels are
~O 94/14541 PCT/BE93100081
3
constructed in such a manner that both the floats and
the sinks move in the same direction and exit on the
same end of the barrel. ~i-directional barrels have
floats and sinks moving in opposite directions relative
to one another and consequently the floats and sinks
each exit at opposite ends of the barrel. In a bi-
directional barrel the floats at the surface of the bath
stream across the length of the barrel mid-section
until they reach their point of overflow at the
discharge end of the floats overflow cone, whereas the
sinks at the bottom of the bath are screwed in the
opposite direction by means of scrolls until they reach
the discharge end of the sinks evacuation cone.
The large majority of heavy media barrels on the
market today are mono-directional. On certain
materials, bi-directionality has its distinct advantages
and embodiments of the present invention relates to bi
directional barrels.
In a bi-directional barrel the raw feed is
introduced near the place where the sinks are evacuated.
In this case, the only practical way of evacuating the
sinks is by means of a scrolled cone. But all such bi
directionai barrels sink evacuation cones are faced with
a very annoying problem which up to now has never been
solved in a satisfactory way namely, how to prevent a
small percentage of floats from working their way toward
the sinks side of the barrel and eventually reporting
with the sinks being screwed up the sinks evacuation
cone.
One solution to this problem '_nvolves injecting
medium at various points in the sinks evacuation cone so
as to flush back down into the barrel any floats that
tend to work their way toward the sink side of the
barrel. Another solution involves two curtains or
barriers running the full length of the central barrel
CA 02152068 1999-06-22
4
mid-section. ThE~se curtains are designed to prevent floats
from getting caught up in the barrel scrolls and thus
working their way toward the sink side of the barrel. Both
of these solut_Lons fail to assure a relatively perfect
segregation of floats from sinks.
A BRIEF DESCRIPTION OF THE INVENTION
Heavy media separation generally involves the
immersion of a raw product in a fairly quiescent fluid
having a density intermediate between the densities of the
two fractions t:o be separated. Upon immersion into the
separation fluid the less dense floats whereas the more
dense fraction sinks. This invention relates to heavy media
scrolled barrel;, and more specifically to heavy media bi-
directional scrolled barrels. It assures that particles
which float on t:he surface of a heavy media bi-directional
barrel do indeed report to the float side of this barrel
and in no way have the possibility of reporting incorrectly
to the opposite sink side of said barrel.
The system according to the present invention is
a system for set>arating solid particles in two fractions by
means of a medium, the specific gravity of said medium
situating inbet:ween the specific gravity of a first
fraction, namely the float fraction, and the specific
gravity of the second fraction, namely the sink fraction,
said system comprising:
(a) a longitudinal scrolled barrel containing a liquid
bath in which the separation takes place,
(b) means associated with said barrel for driving it
rotatively along its longitudinal axis,
CA 02152068 1999-06-22
(c) means for feeding or injecting into said barrel both
the solid particles to be separated as well as the
medium effecting this separation,
(d) means for z°emoving the sink fraction,
(e) means for z°emoving the float fraction,
(f) means for insuring a substantially uniform liquid
level in the bath, and
(g) means to prevent float particles from crossing into
the means for removing the sink fraction, and thus
from reporl:ing with the sink fraction, the said means
consisting of at least one curtain having an upper
edge, a lower edge and lateral edges, the upper edge
being at a level higher than the liquid level in the
bath and the lower edge being at a level permitting
below said lower edge the passage of sink particles
into the means for removing sink particles,
characterized in that lateral edges of the curtain are
agenced so as tc> close the passage between the barrel and
the means for removing the sink fraction in the vicinity of
the liquid leve:L in the bath and in that the means for
removing the sink fraction is a second scrolled barrel
attached to and communicating with the barrel in which
separation takes place or a scrolled part of the barrel in
which separation take place.
According to an embodiment, the means for
evacuating the sink fraction is comprised of a second
scrolled barrel attached to and communicating through an
open end with the barrel in which separation takes place,
said second barrel having at its end adjacent to the open
end of the barrel in which separation takes place an inner
diameter greater than or equal to the inner diameter of
CA 02152068 1999-06-22
6
that open end of the first barrel in which separation takes
place adjacent to said second barrel.
The curtain, for example, encloses an end opening
of the first barrel, such enclosure preventing float
particles in the first barrel from crossing into the second
barrel, or the lateral edges have an end which is adjacent
to a part of a surface adjacent to the junction of the
first barrel with the second barrel or the lateral edges
have an end adjacent to a part of the surface of the flange
linking the first barrel to the second barrel.
According to a particularity of said embodiment
the curtain consists of a central plate provided at each of
its lateral ends with a section directed towards the first
barrel, the freE: end of the section adjacent to the first
barrel bearing a layer of an elastomeric material
The cL.rtain is advantageously held in place by
the means for feeding solid particles and/or medium into
the first barrel. The system can include at least one pipe
for injecting medium into the first barrel selected from
the group consisting of the first barrel and the second
barrel.
According to another embodiment of the invention,
it may comprises a means for assuming a flow of medium
underneath the curtain from its sink side to its float
side. The system could also include means for creating a
higher pressure of the medium on that side of the curtain
nearest a point of discharge of the first fraction.
According to another embodiment of the system
according to the invention, the first barrel is
cylindrical, while the second comprises a part with an
inner space, the shape of which is a truncated cone
CA 02152068 1999-06-22
7
extending between two ends, the diameter of the end
adjacent to the first barrel being greater than the
diameter at the other end. The central axis of said first
and second barrels, which is preferably the rotational
axis, forms an angle less than ten degrees with the
horizontal.
According to a characteristic of an embodiment,
the first barrel at its end opposite to the end adjacent to
the second barrE:l, is provided with a further third barrel
having an inner space which bears the shape of a truncated
cone extending between two ends, the diameter of the end
adjacent to th.e first barrel being greater than the
diameter at th~~ other end. Said other end acts as a
discharge for evacuating the float fraction and a part of
the medium.
According to another embodiment of the system
according to thE= invention, the second barrel is provided
with an element linking at least a part of its scrolls in
such a way that it prevents the liquid from flowing freely
through the linked part of its scrolls. For example, the
element covers at least a part of its scrolls in such a way
that its prevents the liquid from floating freely through
the covered part of its scrolls. In this way, the liquid in
the bath is not disturbed.
In said embodiment, both the first and second
barrels have elements which maintain the level of the
liquid in the bG.th, these elements being either in the form
of a cone or a doughnut, with or without an opening for
removing medium or floating particules from the bath.
The sE:cond scrolled barrel has two basic forms.
The first form allows for the eventual evacuation of the
CA 02152068 1999-06-22
8
sinking solid particles by continuing their movement in the
same direction as in the first scrolled barrel. The second
form allows for the eventual evacuation of said solid
particles by reversing their movement relative to the
direction of their movement in the first scrolled barrel.
In both forms of this second scrolled bagel, the
inner diameter of this second barrel is advantageously
greater than the: inner diameter of the first barrel. This
gives the second barrel an even greater capacity for
removing sinking solid particles. As the sinking solid
particles exit i~he first barrel, they fall downward into
the second barrel where they are eventually evacuated from
the bath. This downward movement implies far less wear,
abrasion and energy relative to other evacuation devices
which all lift t:he sinking solid particles out of the bath.
Since -the inner diameter of this second barrel is
advantageously greater than the inner diameter of the first
barrel, it is pc>ssible to insert curtains which serve, for
example, in the event of separation, to prevent any
floating solid particles from crossing over and reporting
with the sinking solid particles.
Another embodiment of the invention is
characterized in that the second barrel is attached to the
first barrel and is scrolled with respect to the first
barrel in such a way that the evacuation of solid particles
through the second barrel is effected by continuing their
movement in the same direction as in the first barrel, in
which the second barrel is provided with an element linking
at least a part. of its scrolls) in such a way that it
prevents the liquid from flowing freely through the linked
part of scroll(s), the system being provided with two
CA 02152068 1999-06-22
9
curtains closing partly the gap between the first barrel
and the element, the curtains extending down in the bath
for preventing floating particles in the bath from crossing
and reporting with the solid particles passing into the
second barrel.
Another system according to the invention for
treating either solid particles in a liquid bath or a
liquid by mean~~ of solid particles, is comprised of a
single scrolled barrel which is comprised further of two
parts: a first part containing a liquid bath wherein the
separation takes place, and a second part provided with a
means for preventing the freeflow of liquid from out the
bottom of the bath, while at the same time allowing for the
free passage of solid particles through the bottom of the
bath, the barrel being provided with an inner annular
protrusion separating the barrel into the two parts.
According to an embodiment of this system, an element
covers or links at least part or parts of the scrolls or
scroll of the barrel in such a way that it prevents the
liquid from flowing freely through the linked or covered
scrolls or scroll.
Still another system according to the invention
which is particularly suitable for treatment such as
scrubbing is comprised of a single barrel which is
comprised of three parts: namely, a central part wherein
the treatment takes place, a first end part for feeding
solid particles into the central part and which is provided
with means for preventing the freeflow of liquid from out
of the bath and at the same time allowing for the free
passage of solid particles into the central part, a second
end part for evacuating solid particles from the central
CA 02152068 1999-06-22
freeflow of liquid from out of the bottom of the bath while
at the same time allowing for the free passage of solid
particles from 1=he central part through the bottom of the
bath and means :Eor assuring a substantially uniform liquid
level in the bath.
According to an embodiment of said last
embodiment, the barrel is provided with two elements, a
first element linking parts of scrolls or scroll of its
first end part in such a way that it prevents liquid from
10 flowing freely through the linked parts of scrolls or
scroll of said first end part, while the second element
links parts of scrolls or scroll of its second end part in
such a way that it prevents liquid from flowing freely
through the linked parts of scrolls or scroll of said
second end part.
In a preferred embodiment of said last
embodiment, the barrel is provided with an annular
protrusion having such a height that the free end of said
protrusion directed towards said longitudinal axis is
located at a di;~tance from said longitudinal axis which is
at most equal to the distance separating the free ends of
the parts of the: scrolls adjacent to the said inner annular
protrusion, the said inner annular protrusion separating
the central part from the second end part. The barrel is
provided with a:n element linking parts of its scrolls in
its second end part in such a way that it prevents liquid
from flowing freely through the linked parts of scrolls of
said second end. part, and in such a way that a gap is
formed between the said element and the protrusion, said
system being provided with two curtains closing partly said
gap, said cur~~ains extending down in the bath for
CA 02152068 1999-06-22
11
gap, said curtains extending down in the bath for
preventing floating particles from crossing and reporting
with the solid particles passing through the gap.
Advantageously, the barrel is rotated along its
longitudinal axis.
The invention relates as well to a process for
separating solid particles in two fractions by means of a
medium, the specific gravity of said medium situating
inbetween the specific gravity of a first fraction, namely
the float fraction and the specific gravity of the second
fraction, namely the sink fraction.
In said process the solid particles to be
separated as well as medium are fed into a scrolled barrel
or a first part: of a barrel wherein said particles are
separated into a float fraction and a sink fraction. The
float fraction as well as medium stream towards one end of
the scrolled barrel, while at the same time the scrolled
barrel is rotated so as to move the sink fraction towards
the opposite end of the scrolled barrel and furthermore so
as to bring said sink fraction into a second scrolled
barrel attached to and communicating with the first barrel
or into a second part of said barrel. A curtain is
preferably positioned at or near the junction of the two
barrels or party that is, between that end of the first
barrel or nearest to the second barrel or part and that end
of the second barrel nearest to the first barrel or part.
Said curtain serves to prevent the passage of the float
fraction into that part of the second barrel or second part
located between said curtain and the end opposite to the
end to which thE: float fraction stream. The float fraction
as well medium are evacuated at the end of the first barrel
CA 02152068 1999-06-22
12
opposite to the end adjacent to the second barrel or part,
while, as a result of the rotation of the second barrel,
the sink fraction is evacuated at the end of the second
barrel or part opposite to the end to which the float
fraction stream. A higher pressure of the medium is created
on that side of the curtain nearest the means for removing
the sink fraction.
In said process, preferably at least one
parameter selected from among the group consisting of the
speed of rotation of the barrels, the flow rate of the
medium, the feed rate of medium into the first or second
barrels or part:>, the feed rate of solids into the first
barrel or part, etc is controlled so as to obtain a sink
fraction containing less than 0.01% by weight of particles
having a specific gravity lower than the specific gravity
of the medium and at the same time to obtain a float
fraction containing less than 0.01% by weight of particles
having a specific gravity higher than the specific gravity
of the medium.
BRIEF DESCRIPTION OF THE DRAWINGS
- Figure 1 is a. side view with cross-sections of a system
according to 'the invention;
- Figure 2 is a. view along line II-II of the system shown
in Figure 1;
- Figure 3 is a top view with cross-sections of the system
shown in Figure 1;
- Figure 4 is .a view along the line IV-IV of the system
shown in Figure 1;
CA 02152068 1999-06-22
12a
- Figure 5 is a view along the line V-V of the system
shown in Figure 1;
- Figures 6A anal 6B are schematic views of a plant using
an embodiment of the system shown in Figure 1;
~O 94/14541 PCT/BE93/00081
L
13
- Figure 7 is a side view with cross-sections of
another embodiment of a system according to the
invention;
Figure 8 is a cross-section view along the line
VIII-VIII of the system shown in Figure 7;
- Figure 9 is a side view of still another embodiment
of a system according to the invention;
- Figure i0 is a cross-section view along line X-X of
the system shown in Figure 9;
- Figure 11 is a cross-section view along line XI-XI
of the system shown in Figure 10;
- Figure 12 is a side view with cross-sections of a
system according to the invention preferred for
scrubbing solid particles;
- Figure 13 is a side-view of the system of Figure 12
but for the separation of sinking solid particles
from floating solid particles;
- Figure 14 is a cross-section view along line XIV-
XIV of the system of Figure 14;
- Figure 15 is a side view of a further embodiment of
a system according to the invention;
- F figures 16 and i7 are cross-section views ai.ong the
lines XVI-XVI and XVII-XVII of the system of
figure 15, and
- Figure 18 is a cross-section side view of a further
embodiment.
Description of Embodiments
Figure 1 shows a system for separating solid
. 30 particles in two fractions by means of a medium, the
specific gravity of which being comprised between the
specific gravit~r of a first fraction - the floating
fraction and the specifi c gravity of the second fraction .
- the sinking fraction.
WO 94/14541 ~ ~ PCTlBE93/00081"",
14
The system of figure 1 comprises .
(a) a first longitudinal scrolled barrel 1 in whic h the .
separation takes places, said barrel stretching
between a first open end 2 and a second open end
and being provided with five scrolls 41,42,43,44,45
having a right-handed pitch;
(b) means 5 for feeding a mixture medium and solid
particles to be separated;
(c) means 6 for evacuating through an opening 7 the
sink fraction out of the system;
(d) a discharge 8 associated with said barrel 1 for
removing through an opening i0 the float Fraction
as well as the medium;
(e) means 9 associated with said barrel 1 for driving
it rotatively along a longitudinal axis A-A.
The opening 10 of the discharge 8 has a lower edge
101 located at a level 1 lower than the level L of the
lower edge 71 of the opening 7 for the removal of the
sink fraction.
The means 9 rotates clockwise R1 the barrel 1 so as
to ensure the movement of the sink fraction towards the
means 5 for removing the sink fraction (arrow S).
The barrel ? is supported by 10 pneumatic wheels
13 , 14 , five wheels 13 being located on the left side of
the barrel l, while the five other wheels 14 being
located on the right of barrel 1.
Said wheels 13,14 are mounted on shafts 15,16, the
axis B-B, C-C of which are parallel to the central axis
A-A of the barrel 1. Said shafts are held in place by
ball bearings 17 located at the free end of the uprights
18. Shaft i5 is driven by a motor 19, such as an
electrical motor or a diesel motor via pulley 20
connecting sheave 2i secured on shaft 16 with sheave 22.
secured on shaft 23 of the motor 19. Due to the
rotation of the shaft 23 of the motor 19, wheels 13 are
O 94/14541 ~ PCT/BE93/00081
driven so that due to the friction of said wheels 13 on
. barrel 1, the latter is turned along its longitudinal
axis A-a. The means 5 for feeding the mixture of medium
and solid particles to be separated consists of an
5 injector 24 held in position by structure 25. This
injector 24 is inclined so that particles present in
said injector 24 move in the direction of barrel 1. The
free end 26 of said injector 24 is within the inner
separatory space of the barrel i. Near to this free end
10 26, the injector 24 supports a curtain 27 consisting of
a central plate 28 provided at each of its lateral
edges 29 with a section 30 directed towards that end of
barrel 31 connecting to barrel 1.
Like barrel 1, barrel 31 is scrolled. Said barrel
15 31 attaches to and communicates with barrel 1, thereby
acting as means 6 for evacuating the sink fraction.
Said second barrel 31 comprises a first cylindrical part
32 attached by means of a flange 33 to the cylindrical
barrel 1 and a second part 34 with an inner space having
the shape of a truncated cone. Said cone stretches
between two ends 7,341. The diameter D of the cross
ection of the cone 34 at its end 341 adjacent to the
first barrel 1 is greater than the diameter d of the
gross-section of said cone 34 at its other end 7. Said
diameter D corresponds to the diameter of the inner
cross-section of the cylindrical part 32 which is
greater than the diameter E of the inner cross-section
of barrel 1. Said diameter D is advantageously greater
than 1.1 x E, and is preferably comprised between 1.15
~0 x E and 1.25 x E.
in the embodiment as shown, the central axis of the
second barrel 3i correst~onds to the central axis of the
first barrel 1 and is the rotation axis of said barrels.
The sections 30 of the curtain 27 are provided at
their lateral free ends with a layer 35 of an
WO 94/14541 PCTBE93/0008
slastomeric material. Said layers 35 are in very close
proximity to a part of the flange 33 which creates the
junction between the first barrel _ and the second
barrel 31.
5 The upper edge 36 of curtain 27 is at a level X
higher than the level 1 of the point of discharge 10 of
the float fraction and the medium, while the lower edge
37 of curtain 29 is at a level Y permitting the passage
of said sink fraction from barrel 1 to the opening 7 for
10 the evacuation cf the sink fraction.
Said curtain 27 acts therefore as a means to
prevent float particles from crossing into the part of
said second barrel located between said means and the
opening for removing the sink fraction.
15 In order to ensure that float particles near the
curtain 27 will move towards the opening 10 through
barren 1, the curtain 27 features pipes 38 for supplying
medium in the neighbourhood of the curtain 27 and on the
side adjacent to the first barrel 1.
In order to ensure a good separation that only sink
particles pass underneath the curtain 27, medium is
advantageously fed through pipe 129 into that part of
barrel 6 located. between the opening 7 and the curtain
27. In this way a flow of medium underneath the curtain
from its sink side to its float side can be created.
The first scrolled barrel 1 is provided at its end
3 opposite to the end 2 adjacer_t to the second scrolled
barrel 31 with a third barrel 39 which does not have any
scrolls. Said third barrel 39 has an inner space having
the shape of a truncated cone. Said third cone 3° is
attached to and communicates with the first barrel 1.
Said barrel 39 extends t~etween two ends, the
diameter F cf the cross-section of the cone ~t its end
adjacent to the first barrel 1 being greater than the
diameter ~:~ of the cross-section of the cone at its
,rWO 94/14541 PCT/BE93/00081
i~ T
other end. Said barrel 39 has a central axis which
corresponds to the central axis A-A of the barrel 1.
Openings 7 and 10 const~.tute respectively the
discharge for the sink fraction and the discharge for
the float fraction.
The central axis A-A of the barrels forms
advantageously an angle from 1 to 10°, for example 5°
with the horizontal. In order to obtain said
inclination, blocks 50 are placed under the support 55
of the system. the inclination is such that the level
P of the axis at the end of the barrel 1 adj acent to the
barrel 39 is lower than the level Q of the axis at the
end of the barrel 1 adjacent to the barrel 31.
Two pneumatic wheels 51 roll against the outer
surface of the flange 33. Said wheels are mounted on
shafts 52 supported by ball bearings secured at the end
of uprights 54. The axis T of said shaft 52 extends in
a radial direction with respect to the central axis A-A
of the barrel.
Due to the rotation of barrels 1,31 the sink
barticles move towards opening 7 (arrow S).
The system according to t:~e invention is ideally
suited for separating particles with a size from 3 mm up
to 300 mm or even more. These particles cover a broad
range of materials such as non-ferrous metals, plastic,
diamonds, vegetables, etc. The specific gravity of the
medium may be as low as 1.0 and as high as 3.5. The
actual medium is usually water-based with very fine
coi.loidal particles in suspension. Suspension-creating
materials such as clay, sand, magnetite and ferrosilicon
are typically used.
After filing the barrels with medium up to the
level 1, a mixture of medium and solid particles are
?5 conveyed into the barrel 1 by means of an injector 24.
WO 94/14541 .,. ~,_ PCT/BE93/00081",
2~.~~ ~ 1$
The particles are separated i~: said barrel 1 into a
float fraction and a sink fraction. The barrels are
rotated so that due to the rotative screwing effect of
the scrolls, the sink =raction is moved towards the
opening 7 of barrel 31. More specifically, the sink
fraction falls from barrel 1 i:~to barrel 31 and from
there it exits through opening 7. The evacuation of the
sink fraction does not influence the medium in barrel 1.
The curtain 27 blocks float particles from crossing over
into barrel 31 and eventually from joining the sinks
exiting through opening 7. Advantageously medium is
injected in the neighbourhood ef the curtain 27 in the
direction of opening 10 so as to prevent float particles
from congregating near the curtain 27.
Many parameters may be controlled so as to obtain
a satisfactory separation, such as the speed of rotation
of the barrels, the density and viscosity of the medium,
the feed rate of medium into the first or second
barrels, the feed rate of solids into the first barrel,
etc. The curtain 27 assures that r_o float particles
will report with the sink particles being evacuated
through opening 7. More specifically the curtain 27
assures that the percentage of floats in sinks will not
be greater than the percentage ef sinks in Moats, and
that, under normal operating conditions, it becomes
feasible to obtain a sink fraction containing less than
0.01 ~ by weight of particles having a specific gravity
lower than the specific gravity of the medium and at the
same time to obtain a float fraction containing less
than 0.01 ~ by weight of particles having a specific
gravity higher than the specific gravity of the medium.
A prototype of the system according to the
nvention was built. With respect to this prototype as
represented in Figure 1, the characteristics of barrel
.... 1 were as follows diameter E approximately 2.4 meters,
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1
19
diameter D approximately 3.0 meters, diameter d
approximately 1.25 meters, diameter G approximately l.i
meters. The length of barrel 1 was approximately
4.0 meters, while the length of barrel 6 was
approximately 2.0 meters and the length of barrel 8 was
approximately 1.0 meters. The angle a was approximately
3 degrees. The pitch of the scrolls was 1.5 meters and
the number of the scrolls was five. The speed of
rotation of the barrels was varied from 6 to 12 rpm.
Fifty tons per hour of non-ferrous metal particles were
fed to the barrels of which approximately 50 o were
floats and 50 °s were sinks. The medium consisted of
water and atomized ferrosilicon. The specific gravity
of separation was approximately 2.20. Samples of both
floats and sinks were collected over a two-week period
and after analysis they were found to be without any
trace of misplaced material.
Figures 6A and 6B are shematic views of plant using
an embodiment of a system according to the invention.
Said plant comprises .
(a) a conveyor belt 100 for feeding the mixture of
solid particles to be treated,~said mixture comma
from a fragmentizer, for example, as in the case of
a non-ferrous metal application;
(b) an air separator 101 for treating the particles
coming from conveyor belt 100. The function of
this air separator, for example, as in the case of
a non-ferrous metal application, is to remove very
light porous material fabric, textile, foam,
simulated leather, dust and other such materials
which should not enter into the dense medium
circuit;
(c) the system according to the invention (indicated by
99) in which the particles free from this
undesirable light fraction are fed together with
WO 94/14541 ~ ~ ~ ~ ~ PCT/BE93/0008~
the medium through means (injector) 5 and in which
said particles are separated into a sink fraction
and a float fraction;
(d) a chute 102 for collecting medium as well as float
5 particles and for distributing them on a vibratory
screen 103;
(e) a vibratory screen 103 supported by air cushions
105 which in turn are supported by a steel
structure 106, said vibratory screen 103 consisting
.0 of a first section known as a dewatering section
i07a and a second section known as a rinse section
107b;
(f) a medium tank 110 for collecting the medium flowing
through the first section 107a of the vibratory
15 screen 103;
(g) a rinse tank 111 for collecting the rinse water
flowing through the second section 107b of the
vibratory screen 103;
(h) a chute 112 for collecting medium as well as
20 particles and for distributing them on a vibratory
screen 113;
(i) a vibratory screen 113 supported by air cushions
105 which in turn are supported by a steel
structure 10&, said vibratory screen 113 consisting
of a first section known as a dewatering section
114a and a second section known as rinse section
114b;
(j ) a medium tank 115 for collecting the medium flowing
through the first section 114a of the vibratory
screen 123;
ik) a rinse tank 116 for collecting the rinse water
glowing through the second section il4b of the
vibratory screen 113.
'T'he float particles on screen 103 travel first over
the dewatering section 107a and then over the rinse
WO 94/14541 ~~t j ' PCT/BE93/00081
21
c~
section 107b, and finally they exit screen 103 at that
( end opposite chute 102 ~cf arrow fp), whereas the sink
particles on screen 113 travel first over the dewatering
section 114a and then over the rinse section 114b, and
S finally they exist screen 113 at that end opposite chute
112 ( c f arrow f s ) .
Part of the medium collected in tank 110 is
injected through pipe 131 into barrel 1 by means of the
injector S. A second part of said medium is injected
through pipes 38 on the float side of the curtain 27 to
prevent the accumulation of floats near the curtain.
Finally a third part of said medium is injected through
pipe 129 on the sink side of the curtain 27 so as to
create a flow of medium underneath the curtain from its
sink side to its float side. These three parts of the
medium in tank 110 are all pumped out of said tank by
means of the primary medium pump 130. In this way the
primary medium pump 130 also restores to the system the
medium overflowing barrel 8.
A regulation system such as a valve 132 is mounted
on pipe 129 so as to regulate the flow of medium
underneath the curtain 27 from its sink side to its
float side. This assures that onlv sink particles pass
underneath the curtain to its sink side.
The medium collected in tank li5 is pumped by means
of the secondary medium pump 133 through pipe 134 into
the second barrel 6 so as to restore to said barrel the
medium being screwed out together with the sink
particles.
The apparatus 101 comprises a series of trays such
as descending, cascading, vibratory trays 117,118,119.
As the particles drop from one tray to the next, they
are subjected to a current of air so as to deflect the
lighter particles of dust, textile and foam, as in the
case cf a r_on-ferrous metal application, for example,
WO 94/14541 1 , . PCT/BE93/0008~
22
from the heavier particles which are then to report for
further separation to the system according to the
invention 99. The current of air is produced by means
of an injection system comprised for example of special
air nozzles 120 which in turn are fed by a ventilator.
according to a preferred embodiment, each tray has its
own air nozzle and each air nozzle has an openincr whose
length corresponds to the width of the tray. As soon as
the particles to be separated fail from a particular
tray, they are immediately subj ected to a current of air
deflecting the lighter particles in a direction
generally opposite to the movement of the heavier
particles on the trays. The light particles are
deflected in such a manner that they are no longer able
to fall back onto a tray and they fall instead into a
collection bin 125 situated generally underneath the
trays. The collection bin 125 is situated in a sealed
housing 150 which communicated through an opening 151 to
the tray system 101 and which communicates as well as
through an opening 152 to the ventilator which feeds the
air nozzles. Preferably an air filtration unit is
incorporated into the circuit.
The embodiments of Figures 7 to 10 described
hereafter are particularly suitable for heavy media
separation, but are also suitable for other uses, such
scrubbing, treatment cf liquids as waste water with
solid such as lime, dolomite, calcium carbonate.
figure ? shows a system for separating solid
particles in two fractions by means of a medium, the
~0 specific crravity of which being comprised between. the
specific gravity of the first fraction -tine =loating
fraction, and the specific gravity of the second
fraction - the sinkincr fraction. '
The system comprises .
.._ tai a first longitudinal scrolled barrel 201 in which
~O 94/14541 ~ PCT/BE93/00081
23
the separation takes place, said barrel being
provided with five scrolls 241,242,243,244,245
having a right-handed pitch;
(b) means 205 for feeding a mixture medium and solid
particles to be separated;
(c) means 206 for evacuating through an opening 207 the
sink fraction out of the system;
(d) a discharge 208 in the form of a cone associated
with said barrel 201 for removing through an
opening 210 the float fraction as well as medium,
and
(e) means 209 associated with said barrel 201 for dri-
ving it rotatively along a longitudinal axis A-A.
The opening 210 of the discharge 208 has a lower
edge 301 located at a level LL lower than the level LLL
of the lower edge 271 of the opening 272 through which
the mixture is fed into the barrel 201.
The means 209 rotates clockwise R1 the barrel 201
so as to ensure the movement of the sink fraction
towards the means for remowing the sink fraction
( arrow S ) .
The barrel 201 is supported by pneumatic tyres 213.
Seven tyres 21.3 are located on the left side of the
barrel 201 while seven other tyres 214 being located on
the right side of barrel 201.
Said tyres 213 are mounted on shaft 215, the axis
B-B of which are parallel to the central axis A-A of the
barrel 201. Said shafts are held in place by ball
bearings 217 located at the free end of uprights 218.
One shaft as driven by a motor (not shown) such as an
electrical motor or a diesel motor, via pulley
connecting a sheave secured on shaft with a sheave
secured on the shaft of the motor. Due to the rotation
of the shaft of the motor, tyres 213 are driven so that
due to the friction of said tyres 213 on barrel 201,
WO 94/14541 PCT/BE93/0008
24
the latter is turned along its longitudinal axis A-A.
The means 205 for feeding the mixture of medium and
solid particles to be separated consists of an injector
224 held in positicn by a structure225. This injector ,
224 is inclined so that particles present in said
injector 224 move in the direction of barrel 201, said
inj ector 224 is within the inner separatory space cf the
barrel 201.
Like barrel 201, barrel 231 is scrolled. paid
0 barrel 231 attaches to and communicates with barrel 201,
thereby acting as means 206 fcr evacuating the sink
fraction.
~n the embodiment as shown, the central axis o~ the
second barrel 231 corresponds to the central axis c~ the
15 first barrel 201 and is the rotation axis of said
barrels.
The barrel 231 is attached to barrel 201 by means
of scrolls 232,233 of barrel 231. Barrel 201, i.e. its
outer surface, acts as element for linking scrolls of
20 barrel 231 so as to define a passage 234 wherein scrolls
stretch so as to prevent the freeflow of medium through
said passage and the opening 207.
The second barrel ~31 is provided with an end wall
or doughtnut 236 showing the opening ~72 t::.rough which
25 the solid particles to be treated are fed through the
injector 224, said end wall or doughnut 235 acting as
means for preventing any flow of -medium out of the
barrel 231 in a directicn opposite to barrel 201.
Thus, the freeflow cf medium M out of the system is
0 cnly possible through opening 210, while the removal of
medium through opening 207 with sinking particles is not
free as it depends on the rotation speed of the barrels
201,231.
~n the embodiment of = figure 7, barrel 3 is provided
25 with scrolls having a right-handed pitch, while barrel
O 94/14541 PCT/BE93/00081
231 is provided with scrolls having left-handed pitch
ti. e. barrels 201 and 231 have scrolls with opposite
handed pitch). The evacuation of sinking particles is
thus cbtained by reversing their movement relative to
their movement in the first barrel.
In the embodiment shown, the central axis A-A is
horizontal so that for evacuating the sink fraction out
of the system, it is not necessary to raise upwardly the
said sink fraction.
10 Barrel 231 has an inner diameter which is greater
than the outer diameter of the barrel 201 so that the
sinking particles escaping barrel 201 fall into barrel
231, whereby the sinking particles do not disturb the
. treatment of solid particles into barrel 201.
15 When the system of Figure 7 is used for separating
sinking solid particles from floating particles, the
system is advantageously provided with curtains 239
extending down in the bath for preventing floating
particles F from crossing and reporting with the solid
20 particles passing through the bottom of the bath BA into
the barrel 231, i.e. all the floating particles F are
evacuated through the opening 210.
The curtains are attached to arm 240 attached to
the injector 224. The curtains are comprised of an arc
25 section of a cylinder, one end edge 391 contacts the
doughnut 226 while the other end of which contacts the
element or first barrel 201.
Figure 9 is a view of a system similar to that
shown in Figure 7, except that barrel 231 is attached to
barrel 201 by means of a flange 237 and forms an
extension of barrel 201.
An inner cvlinder 238 covers the free end of
scrolls of the second barrel 231 so as to define a
passage 234 wherein scrolls stretch, said passage acting
as means for evacuating sinking solid particles.
WO 94/14541 PCT/BE93/00081-
~~ 26
The end of the cylinder 238 opposite to the end
adjacent to barrel 201 is provided with a doughnut 236
having an opening 272 through which the solid particles
are fed in barrel 201 together with medium by means of
.. the injector. Said doughnut acts as means for
preventing medium to flow freely out cf the barrel 231
through the opening 272, as the level LLL of the lower
edge 271 of the opening 272 is located upwardly with
respect to the lower edge 301 cf the opening 210.
Said doughnut and the cone 208 act as means for
assuring a substantially uniform level of the bath, i . a .
for assuring a maximum level of the bath BA.
In said embodiment, the sinking particles are
evacuated through opening 207 by continuing their
movement S2 in the passage 234 in the same direction S
as in the first scrolled barrel.
As solid particles deposit on the inner surface of
the cylinder 238, said inner surface is advantageously
provided with scrolls 381 having a pitch opposite to the
pitch of the first barrel 201, so that, when the barrels
201, 231 rotate, the sinking particles deposited on
barrel 201 move (S) towards the gap G formed between the
cylinder 238 ar_d the barrel 201, while the sinking
particles deposited on the inner surface of the cylinder
238 also move (Si opposite to S) towards said gap G,
i.e. so that the sinking particles fall into the barrel
231.
The solid particles falling in the barrel 231 are
then moved towards the opening 207 through the scrolls
of said barrel 231.
The parts c~ the scrolls 311 of the barrel 231 '
located in the gap G have advantageously such a height
h that a curtain 239 is able to stretch from the outer '
surface of the cylinder 238 towards the first barrel,
.... preferably to the flange 237.
~WO 94/14541 PCTlBE93/00081
27
The embodiments cf Figures 7 and 9 overcome the
difficulties surrounding the evacuation of solids from
a liquid bath. It allows ~.arge quantities of solid
particles to be evacuated simply and efficiently with a
small initial capital cost, requiring little energy or
power, and incurring little wear or abrasion. In fact,
in its such embodiments, it even allows solid particles
to be removed from a liquid bath without having to lift
the particles out of the bath and at the same time
without disturbing the dynamics of the bath in any
significant way. The present invention, in these
embodiments, in evacuating solid particles from a liquid
bath, does not require any upward movement of the solid
particles relative to the bath, and it does not require
that the solid particles be lifted to some point above
the bath.
As in the system of Figure 7, two curtains 239 (arc
section of a cylinder, the inner diameter of which is
equal to or greater than the inner diameter of barrel
201 and than the inner diameter of cylinder 238) are
secured to the injector 224 by means of arms 240. Said
curtains contact the flange 237 and the cylinder 238 and
extend down in the bath BA for preventing =loating
particles from crossing and reporting with the sinking
solid particles. Advantageously, the edges of the
curtains making contact consist of an elastomeric
material.
Figure 12 is a view of another embodiment of a
system according to the invention, which is also
suitable and preferred for the scrubbing cf the solid
particles.
The system comprises a scrolled barrel 201
comprising three parts, a central part 1000 wherein the
treatment takes place, a first end part 1001 for feeding
solid particles into the central part and a second end
WO 94/14541 PCT/BE93I00081~
28
part 1002 for evacuating solid particles through the
bottom cf the bath of the central part 1000.
Scrolls of the first end part 1001 are linked by a
cylinder 1003 so as to define a passage 341. The
scrolls stretching in the said passage 341 preventing
the Treeflow from out of the bath BA through said
passage.
The cylinder 1003 is provided with a doughnut 1004
so as to crevent any flow of medium from cut the inner
space 351 of cylinder 1003 in a direction opposite to
the central part _000.
Scrolls of ~he second end part 1002 are linked by
a cylinder 1005 so as to define in said end part a
passage 342. Scrolls stretching in the passage prevent
the freeflow of medium through said passage 342.
The cylinder 1005 is provided with a doughnut 1006
having an opening 210 through which medium and float
fraction are possibly discharged.
The cylinders 1003 and 1005 are provided with
scrolls 1007 so as to ensure that any sinking particles
deposited thereor_ will move towards the central part
1000 so as to be treated again or so as to be evacuated
through passage 342.
Barrel 1 is provided with a scrolled extension 1008
with a wail 1009 in which the solid particles to be
treated and possibly medium for the treatment are fed by
means of the injector 224.
Cylinder 1005 is also provided with an extension
1010 in order ~o avoid that medium and floating
particles F flowing through the opening 210 are mixed
again with the medium and sinking particles S flowing
through the opening 207.
The means for driving into rotation barrel 201 are
for example similar to that disclosed for the system of
Figure ?.
WO 94/14541 ~ ~ p PCT/BE93/00081
29
The system of Figure 13 is similar to that shown in
Figure 12, except that it is provided with curtains for
preventing floating particles from crossing over and
reporting rote the sinking solid particles removed
' _ through the passage 342. Such a system is thus
particularly suitable For separating sinking solid
particles from floating particles.
The barrel is provided with an inner annular
protrusion 1011 which forms a separation between the
central part 1000 and the second end part (evacuation)
1002, a gap G being so created between said annular
protrusion 1011 and the cylinder 1005. The height hI of
the protrusion 1011 is advantageously lower to the
height h2 of the passage 342 and therefore to the height
h2 of the scrolls of the second end part 1002.
The scrolls of the central part 1000 have a height
equal to the height of the scroll in the second end
part, except that said height decreases in the
neighbourhood of the annular protrusion 1011.
The inner surface of cylinder 1005 is, in the
~:eighbourhood cf the annular protrusion 1011, not
crovided with scroll so as to form a contact surface for
curtains 239 fer preventing floating particles from
crossing and retorting with the sinking solid particles .
The system is provided with two curtains attached
to an arm 1012 of a structure, said arm 1012 stretching
through the opening 210 through which floating particles
are removed. The curtains 239 close partl y the gap G
formed between she annular protrusion 1011 and the
~0 cylinder 1005 ar~d extend down into the bath BA. The
curtains 239 iirL the form cf an arc section of a cone)
have two opposite edges 391, 392, a first contacting the
surface 1013 of the crotrusion directed towards the
longitudinal axis A-A of tine barrel while the other
contacts the _nner surface 1014 of the cylinder 1005,
WO 94/14541 PCT/BE93/00081-
t ~ 30
contacts the inner surface 1014 of the cylinder 1005,
which is not provided with scrolls.
Figure 15 is a view of a Further embodiment
according to the invention.
T_n this embodiment, tine system comprises .
- a scrolled barrel 201 in which the separation takes
place ;
- an injector 224 for feeding the barrel 201 with
medium and particles to be treated ;
- a cone 208 attached to and communicating with the
barrel 201, said cone having an opening 210 for
evacuating floating particles and medium;
- a barrel 206 attached to and communicating with the
barrel 201 for the evacuation of sinking particles
and medium, and
- means for driving rotatively the barrels so that
floating particles (M) and sinking particles (S)
flow in opposite direction.
Scrolls of barrel 206 are linked together by means
of a cylinder 1005 which is provided with a doughnut
1009 with a central opening 1020 through which injector
224 passes so as to feed barrel 201 with particles to be
treated.
Said cylinder 1005 and doughnut 1009 prevent the
freeflow of medium and sinks out of the system.
Barrel 201 is provided with an inner annular
protrusion 1012 having a part 1021 reducing
progressively the inner cross-section or/and diameter
of barrel 201 and provided with the scrolls 1022
intended to raise sinks with respect to the bottom of
barrel 201. Such an inner protrusion due to the raise
of sinks and due to the reduction of cross-section of
barrel 201 (reduction of the velocity of medium towards
barrel 206) acts already as means for preventing as much
as possible floats to retort with sinks.
~WO 94/14541 PCT/BE93/00081
31
So as to ensure an excellent separation, the system
.s further provided with a curtain 27 having an upper
edge at a level higher than the level cf the bath, a
lower edge at a level allowing the passage of sinks and
.. lateral edges contacting a surface of barrel 201 but
preferably a part 1023 of the protrusion 1012, part '_023
which is free of scrolls. For example, part 1023
increases prcgressively the cross-section or diameter of
the barrel 206 with respect to the minimum cross-section
iG or diameter due to the protrusion 1012, so that sinks
passing over the upper edge 1024 of the protrusion slip
or glide on said part 1023 towards barrel 206. Part
1023 forms thus a slope which is contacted by the
lateral edges of the curtain 27, the form of which is a
15 section of a circle.
The maximum height h1 of the protrusion 1012 with
respect to barrel 201 is advantageously equal to,
preferably greater than, the height h2 of the scrolls of
the barrel 206.
20 Figure 18 shows an embodiment similar to that shown
in Figure 12. Said embodiment is advantageously
provided with a curtain 27 such as shown -n the
embodiment of figure 13.
In the embodiment of Figure 18, cylinder 1003 is
25 closed by two doughnuts 1004a, 1004b, whereby there is
no treatment bath BA in the inner space of said
cylinder, whereby there is also no need to provide said
cylinder with any scrolls.
Cylinder 1005 is provided with a doughnut 1006 with
30 an opening 210 located in the inner space of barrel 201.
Said doughnut 1006 is advantageously attached to the end
cf the cylinder 1005 directed towards to injector 224 or
cylinder 3.003, whereby there is no need to provide
cylinder 1005 with scrolls. However, in specific
?5 embodiment cyl-nder 1005 may be provided with scrolls so
WO 94/14541 PCTBE93/0008~
32
as to facilitate the evacuation of medium and floats (F?
through opening 210 into cylinder 1005.
?,n advantage to use doughnut 1006 and 1004b located
~n the barrel 201 is to limit the weight cf treatment
bath in the barrel 201 and therefore to limit the power
reauired for the rotation thereof.
When using a curtain 27, said curtain 27 will, yor
example, extend between the doughnut 1006 and an annular
crotrusion such as disclosed in Figure 13 or in Figure
1 0 15 .
