Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FLOTATION ARRANGEMENT AND runnlop
BACKGROUND
The invention relates to a flotation arrangement.
The invention further relates to a method for flotation.
There are needs for improving the effectiveness of the
flotation in processes for liberating valuable minerals
form mineral ore.
BRIEF DESCRIPTION
Viewed from a first aspect, there can be provided a flota-
tion arrangement, comprising a mill arranged for producing
slurry, a flotation section comprising at least one flota-
tion unit, provided with a feed system for receiving slur-
ry to be handled in said flotation unit, an overflow means
for removing flotation concentrate, an outlet for removing
underflow. The flotation unit comprises a fluid bed device
comprising devices for creating a fluid bed and/or a froth
device comprising devices for creating a froth layer,
wherein particles are fed for interaction with the froth
layer in the froth layer, under the froth layer to close
proximity thereof, or above the froth layer, or any combi-
nations thereof. The flotation section is followed by a
first classification unit, and the flotation section (12)
is arranged for receiving, from the mill, slurry feed from
which particles under 300 pm are not removed. The flota-
tion section is operably connected to an inlet of the
first classification unit for classification of said un-
derflow exiting from the flotation section into a fine un-
derflow stream (F) and a coarse underflow stream that is
tailings.
Thereby a flotation arrangement where it is handled a
broad particle size distribution of particles containing
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both finer and coarser particles is achieved. It is sur-
prisingly discovered that a very effective flotation of
coarser particles containing valuable minerals is achieved
due to fact that said coarser particles are combined with
finer particles. Some portion of finer particles, however,
containing valuable minerals arrives in underflow of flo-
tation, from where they are recovered in first classifica-
tion unit. Additionally, the arrangement allows upgrading
of the fine particles.
Viewed from a second aspect, there can be provided a meth-
od for flotation, the method comprising
- creating a slurry feed in a mill,
- feeding the feed from which particles under 300 pm are
not removed from the mill to a flotation section compris-
ing at least one flotation unit, wherein the flotation
unit (1) comprises a fluid bed device comprising devices
for creating a fluid bed and/or a froth device comprising
devices for creating a froth layer, wherein particles are
fed for interaction with the froth layer in the froth lay-
er, under the froth layer to close proximity thereof, or
above the froth layer, or any combinations thereof,
- removing a flotation concentrate as an overflow from the
flotation section,
- removing an underflow from the flotation section,
- feeding the underflow to a first classification unit,
and
- classifying the underflow into a fine underflow stream
and a coarse underflow stream in the first classification
unit.
Thereby a method for flotation handling a broad particle
size distribution of particles containing both finer and
coarser particles is achieved. It is surprisingly discov-
ered that a very effective flotation of coarser particles
containing valuable minerals is achieved due to fact that
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said coarser particles are combined with finer particles.
Some portion of finer particles, however, containing valu-
able minerals arrives in underflow of flotation, from
where they are recovered in a first classification unit.
Additionally, the method allows upgrading of the fine par-
ticles.
The arrangement and the method are characterised by what
is stated in the independent claims. Some other embodi-
ments are characterised by what is stated in the other
claims. Inventive embodiments are also disclosed in the
specification and drawings of this patent application. The
inventive content of the patent application may also be
defined in other ways than defined in the following
claims. The inventive content may also be formed of sever-
al separate inventions, especially if the invention is ex-
amined in the light of expressed or implicit sub-tasks or
in view of obtained benefits or benefit groups. Some of
the definitions contained in the following claims may then
be unnecessary in view of the separate inventive ideas.
Features of the different embodiments of the invention
may, within the scope of the basic inventive idea, be ap-
plied to other embodiments.
In one embodiment, the flotation unit comprises devices
for creating a fluid bed. An advantage is that valuable
particles are floated and at least most of fine particles
are recovered. This allows an immediate disposal of coarse
tailings. Another advantage is that the fine particles can
processed downstream in standard flotation equipment with
a higher separation efficiency.
In one embodiment, the flotation unit comprises devices
for creating a froth layer, wherein particles are fed for
interaction with froth layer in the froth layer, under the
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froth layer to close proximity thereof, or above the froth
layer, or any combinations thereof. An advantage is that
the size of the flotation unit may be reduced, a high
throughput per flotation unit volume may be achieved, and
an immediate interaction with froth/bubbles leading to a
potentially higher recovery.
In one embodiment, the flotation unit comprises the devic-
es for creating a fluid bed and the devices for creating a
froth layer, wherein particles are fed for interaction
with froth layer in the froth layer, under the froth layer
to close proximity thereof, or above the froth layer, or
any combinations thereof. An advantage is that the recov-
ery of coarse valuable minerals to concentrate may be max-
imized.
In one embodiment, the classification unit comprises a
classification cyclone. An advantage is that simple struc-
ture without moving parts can be achieved.
In one embodiment, the fine underflow stream from the
first classification unit is arranged to be fed to a flo-
tation system comprising at least one flotation vessel. An
advantage is that valuable minerals may be recovered.
In one embodiment, the flotation vessel is a fluid bed de-
vice comprising devices for creating a fluid bed. An ad-
vantage is that recovery of near-floating particles may be
improved with added buoyancy of fluid bed.
In one embodiment, the flotation vessel is a device com-
prising devices for creating a froth layer, wherein parti-
cles are fed for interaction with froth layer in the froth
layer, under the froth layer to close proximity thereof,
or above the froth layer, or any combinations thereof. An
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advantage is that recovery of particles may be improved
due to immediate addition to the froth layer.
In one embodiment, the flotation system comprises at least
5 three flotation vessels arranged in series such that the
outlet for removing underflow of a preceding flotation
vessel is connected to the inlet of a following flotation
vessel. An advantage is that valuable minerals in the un-
derflow may be recovered.
In one embodiment, the flotation vessel comprises the de-
vice comprising an inlet connected for receiving feed to
be handled in said flotation vessel and arranged to a low-
er part of the flotation vessel, an overflow means for re-
moving flotation concentrate, arranged to an upper part of
the flotation vessel, and an outlet for removing under-
flow, arranged to a lower part of the flotation vessel. An
advantage is that a high recovery may be achieved due to a
high energy input and good mixing properties.
In one embodiment, the flotation vessel comprises a me-
chanical agitator for agitating surry in said vessel. An
advantage is that separation of particles containing valu-
able minerals from other particles may be intensified.
In one embodiment, the flotation vessel comprises a me-
chanical agitator for creating bubbles in said vessel. An
advantage is that separation of particles containing valu-
able minerals from other particles may he intensified.
In one embodiment, the flotation vessel comprises a closed
vessel for a pressurized flotation, wherein flotation con-
centrate is removed by pressure from the vessel. An ad-
vantage is that a high recovery may be achieved since
there are no losses in the froth.
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In one embodiment, the flotation vessel comprises devices
for pneumatical gas addition. An advantage is that a bet-
ter product grade and/or improved recovery of fine parti-
cles may be achieved.
In one embodiment, at least one of the flotation vessels
is a froth separation device comprising devices for creat-
ing a froth layer, comprising an inlet connected for re-
ceiving feed to be handled in said flotation vessel and
arranged to an upper part of the flotation vessel, an
overflow means for removing flotation concentrate, ar-
ranged to an upper part of the flotation vessel, and an
outlet for removing underflow, arranged to a lower part of
the flotation vessel. An advantage is that a high product
grade may be achieved.
In one embodiment, the flotation vessel comprises a down-
comer for slurry infeed, the downcomer equipped with a
nozzle for feeding pressurized flotation gas in slurry
therein. An advantage is that a high recovery may be
achieved resulting from a localized high energy input.
Another advantage is that especially fines recovery may be
enhanced.
In one embodiment, the downcomer comprises an outlet noz-
zle configured to induce a supersonic shockwave into the
slurry as it exits the downcomer. An advantage is that
flotation of fine and ultrafine particles comprising for
example mineral ore or coal may be improved.
In one embodiment, the arrangement comprises a second sep-
aration unit arranged for preventing large particles en-
tering in the first classification unit. An advantage is
that particles containing valuable minerals but too large
for entering in the fine underflow stream may be recov-
ered.
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In one embodiment, the second separation unit is arranged
before the flotation unit for preventing large particles
entering in said flotation unit and the first classifica-
tion unit. An advantage is that it is possible to avoid
feeding in the flotation unit particles containing valua-
ble minerals but too large for entering in the fine under-
flow stream.
In one embodiment, the second separation unit is arranged
between the flotation unit and the first classification
unit. An advantage is that particles containing valuable
minerals but too large for entering in the fine underflow
stream may be recovered.
In one embodiment, the second separation unit comprises a
grizzly or a grating. An advantage is that a simple struc-
ture of the separation unit may be achieved.
In one embodiment, the second classification unit is con-
nected to the mill for returning large particles back to
the mill for further grinding. An advantage is that large
particles containing valuable minerals may be grinded in
size that may enter in the fine underflow stream.
In one embodiment, the flotation unit is deployed in an
open-circuit configuration. An advantage is that a config-
uration that is simple, has reduced energy usage and low
capex and running costs may he achieved.
In one embodiment, the flotation unit is deployed in a
closed-circuit configuration. An advantage is that recir-
culation of particles may enhance recovery of valuable
minerals.
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BRIEF DESCRIPTION OF FIGURES
Some embodiments illustrating the present disclosure are
described in more detail in the attached drawings, in
which
Figure 1 is a schematic view of an arrangement and a meth-
od,
Figure 2 is a schematic view of another arrangement and
method,
Figure 3 is a schematic view of a flotation system and a
method,
Figure 4 is a schematic view of another flotation system
and a method, and
Figure 5 is a schematic view of a third flotation system.
In the figures, some embodiments are shown simplified for
the sake of clarity. Similar parts are marked with the
same reference numbers in the figures.
DETAILED DESCRIPTION
Figure 1 is a schematic view of a flotation arrangement
100 and a method.
The arrangement 100 comprises a mill 2 arranged for pro-
ducing slurry, and a flotation section 12 comprising at
least one flotation unit 1.
The mill 2 may be e.g. an autogencus grinding mill, or a
semi-autogenous grinding mill, or a high-pressure grinding
roll.
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In the embodiment shown in Figure 1, the flotation section
12 includes one flotation unit 1. In another embodiments,
there may be two, three or even more flotation units in
the flotation section. If there are plurality of flotation
units, they all may be of same type, or alternatively,
there may be at least two types of flotation units.
The flotation unit 1 comprises a feed system 3 arranged to
receive slurry to be handled in said flotation unit 1 from
which slurry particles under 300 pm are not removed. The
location of the feed system 3 depends on the type of the
flotation unit 1. Thus, the feed system 3 may be located
to a lower part, to an upper part or to a mid-part of the
flotation unit 1.
The flotation unit 1 further comprises an overflow means 4
for removing flotation concentrate from said flotation
unit, and an outlet 5 for removing underflow from said
flotation unit.
In embodiments comprising plurality of flotation units,
the units are in series such that a first of the of flota-
tion units 1 is arranged to receive slurry to be handled
in the flotation section 12, and the outlet 5 of a preced-
ing flotation unit 1 is connected to the feed system 3 of
a following flotation unit 1. The last one of the plurali-
ty of flotation units 1 is arranged to remove underflow
from the flotation section 12.
The arrangement 100 further comprises a first classifica-
tion unit 6 comprising an inlet 7. The inlet 7 is arranged
for receiving underflow from the flotation section 12. The
first classification unit 6 is adapted for classification
of the underflow into a fine underflow stream F and a
coarse underflow stream that is tailings.
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In an embodiment, the flotation unit 1 comprises a fluid
bed device comprising devices for creating a fluid bed in
the flotation unit 1. In another embodiment, the flotation
unit 1 comprises a froth device that has devices for cre-
5 ating a froth layer in the flotation unit 1. The froth
layer may interact with particles of the product stream.
In an embodiment, the product stream is arranged to be fed
in the froth layer, under the froth layer to close proxim-
ity thereof, or above the froth layer, or any combinations
10 thereof. The term "close proximity" means distance of 20
cm or less from the froth layer in this description.
In an embodiment, the product stream is arranged to be fed
in the froth layer, under the froth layer not more than 2
cm therefrom, or above the froth layer, or any combina-
tions thereof.
In an embodiment, the flotation unit 1 comprises both the
devices for creating a fluid bed and the devices for cre-
ating a froth layer.
In an embodiment, the first classification unit 6 compris-
es a cyclone. In another embodiments, the first classifi-
cation unit 6 comprises, in addition to or as an alterna-
tive to a cyclone, one or more of a non-mechanical sedi-
mentation classifier, e.g., a settling cone; a mechanical
sedimentation clas-sifier, e.g., a rake classifier or a
spiral classifier; a free-settling classifier; and a hin-
dered-settling classifier, e.g., a hydrosizer.
In an embodiment, the fine underflow stream F is fed from
the first classification unit 6 to a flotation system 20
comprising at least one flotation vessel 21. The flotation
system 20 is discussed more detailed in connection with
Figures 3 and 4.
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Figure 2 is a schematic view of another arrangement and a
method.
In an embodiment, the arrangement comprises a second sepa-
ration unit 13 that is arranged for preventing large par-
ticles entering in the first classification unit 6. The
large particles may contain valuable minerals, but they
are too large for entering in the fine underflow stream F.
In an embodiment, such as shown in Figure 2, the second
separation unit 13 is arranged between the flotation unit
1 and the first classification unit 6. In another embodi-
ment, the second separation unit 13 is arranged before the
flotation unit 1 for preventing large particles entering
also in the flotation unit 1.
In an embodiment, the second classification unit 13 com-
prises a grizzly or a grating.
In an embodiment, such as shown in Figure 2, the second
classification unit 13 is connected to the mill 2 so that
large particles can be returned to the mill 2 for further
grinding.
Figure 3 is a schematic view of a flotation system and a
method and Figure 4 is a schematic view of another flota-
tion system and method. The flotation system 20 is ar-
ranged in fluid communication with the first classifica-
tion unit 6 described in this description so that the fine
underflow stream F created in the first classification
unit 6 is fed to the flotation system 20 that comprises at
least one flotation vessel 21.
In an embodiment, the first classification unit 6 is oper-
ated in an open-circuit configuration, i.e. without recir-
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culation of material back into the first classification
unit 6.
In an embodiment, the flotation vessel 21 is one of the
following:
a fluid bed device comprising devices for creating a fluid
bed, or
a device comprising devices for creating a froth layer,
wherein particles are fed for interaction with froth layer
in the froth layer, under the froth layer to close proxim-
ity thereof, or above the froth layer, or any combinations
thereof, or
a device comprising devices for pneumatical gas addition,
or
a closed vessel for a pressurized flotation, wherein flo-
tation concentrate is removed by pressure from the vessel,
or
a device (such as shown in Figure 3) comprising an inlet
22 connected for receiving feed to be handled in said flo-
tation vessel and arranged to a lower part of the flota-
tion vessel 21, an overflow means 15 for removing flota-
tion concentrate, arranged to an upper part of the flota-
tion vessel (21), and an outlet 25 for removing underflow,
arranged to a lower part of the flotation vessel 21. The
term 'close proximity" means distance of 20 cm or less
from the froth layer in this description.
In an embodiment, the flotation system 20 comprises at
least three flotation vessels 21 arranged in series such
that the outlet 25 for removing underflow of a preceding
flotation vessel 21 is connected to the inlet 22 of a fol-
lowing flotation vessel 21. In an embodiment, all the flo-
tation vessels 21 in the flotation system 20 are of same
type. In another embodiment, there are at least two types
of flotation vessels 21 in the flotation system 20.
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In an embodiment, the flotation vessel 21 comprises a me-
chanical agitator for agitating surry in said vessel. Ad-
ditionally, or alternatively, a mechanical agitator may be
used for creating bubbles in the vessel.
In an embodiment, (such as shown in Figure 4) the flota-
tion vessel 21 is a froth separation device comprising de-
vices for creating a froth layer, wherein an inlet 22 con-
nected for receiving feed to be handled in said flotation
vessel is arranged to an upper part of the flotation ves-
sel 21, an overflow means 15 for removing flotation con-
centrate is arranged to an upper part of the flotation
vessel 21, and an outlet 19 for removing underflow is ar-
ranged to a lower part of the flotation vessel 21.
In an embodiment, the flotation vessel 21 comprises at
least one downcomer that feeds slurry in the vessel. The
downcomer is equipped with a nozzle for feeding pressur-
ized flotation gas in slurry therein. Additionally, the
downcomer comprises an outlet nozzle that is configured to
induce a supersonic shockwave into mixture of gas and
slurry as it exits the downcomer.
Figure 5 is a schematic view of a third flotation system.
As already disclosed, in an embodiment the flotation ves-
sel 21 is a closed pressurized vessel where pressurized
flotation may take place and wherefrom the flotation con-
centrate is removed by pressure. In an embodiment, no
froth is created in the vessel, but loaded bubbles are
collected before a froth is generated.
An inlet 22 may be arranged to a lower part of the flota-
tion vessel 21, an overflow means 15 may be arranged for
removing flotation concentrate to an upper part of the
flotation vessel 21, and an outlet 19 for removing under-
-Flow may he arranged to a lower part of the flotation yes-
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sel 21. The flotation vessels 21 may be installed on the
same level (as shown), since flowing from a vessel to next
vessel takes place by virtue of pressure created in the
vessels.
In an embodiment, an outlet 19 for removing underflow may
be arranged to an upper part of the flotation vessel 21.
In an embodiment, the pressurized vessel comprises a me-
chanical agitator. One example of this kind of vessel is
known as "Direct Flotation Reactor- (DFR).
It is to be noted here that all the flotation vessels 21
arranged in the flotation system 20 may be of same type,
or alternatively, there may be at least two types of flo-
tation vessels.
The invention is not limited solely to the embodiments de-
scribed above, but instead many variations are possible
within the scope of the inventive concept defined by the
claims below. Within the scope of the inventive concept
the attributes of different embodiments and applications
can be used in conjunction with or replace the attributes
of another embodiment or application.
The drawings and the related description are only intended
to illustrate the idea of the invention. The invention may
vary in detail within the scope of the inventive idea de-
fined in the following claims.
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REFERENCE SYMBOLS
1 flotation unit
5 2 mill
3 feed system
4 overflow means
5 outlet
6 classification unit
10 7 inlet of classification unit
12 flotation section
13 second separation unit
15 overflow means
flotation system
15 21 flotation vessel
22 inlet of flotation vessel
outlet for underflow
100 arrangement
fine underflow stream
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