Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a method for clean-
ing the matrix of a magnetic separator, the cleaning being
carried out by means of a -fluid medium.
Furthermore, the invention is also related to an
apparatus for carrying out the method and, finally, to a method
for operating the apparatus.
Magnetic separators working on the basis of the hold-
back principle are, as a rule, used for treating of flows with
relatively high throughputs, e.g., such within the range of
20 to 200 tons/hour and are, in addition, particularly suitable
for sorting weakly magnetic materials. The operation of such
hold-back-wet magnetic separators is characterized by the fact
that a possibly high magnetic field is generated in a definite
working volume, in the so-called separation space, or within
the internal space of the coil, e.g., by the application of
poles. Within this working volume, there are induction poles
arranged in the form of suitable magnetizable ferromagnetic
bodies which, due to their high permeability, distort the mag-
netic field so that strong inhomogeneities are created and re-
~0 quired gradients will be formed at a number of advantageous
spots in the volume of the separation space. The arrangement of
Eerromagnetic bodies within the corresponding separation space
i5 termed as a "matrix". When a sludge charged with susceptible
particles is led through the matrix, the magnetic material con-
tained in the sludge is held back on the ferromagnetic bodies
as a result of high, local, magnetic forces. Subsequently,
this material held back is washed out of the matrix, as a rule,
by means of a forceful water jet.
In the case of discontinuously or intermittently work-
ing separators, the above operation is carried out by periodic-
ally switching-off the magnetic field so that the magnetic mat-
erial could be washed out of the matrix in this switched off
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state. Under practical conditions, however, continuously working
separators are always increasingly used, e.g., the Jones-separa-
tor or the caroussel separator.
In the case of such continuously operating separators,
the magnetic material, together with the matrix, is first removed
from the magnetic field, then washed out so that the cleaned
matrix be ready for the next operation through the magnetic field.
In accordance with the type of the magnetic material, it may be
required -that the magnetic material be cleaned from the attached,
non-magnetic material particles by means of a wash process carried
out within the magnetic field.
Besides, it is a frequently occurring requirement to
prol~cts
obtain intermediate pr~t. This is carried out by washing out
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a portion of magnetic material, together with the attached deads,
within the magnetic field at a reduced washing energy.
On the practical level, the following are used as in-
duction poles:
- plates with overhanging edges
- profile rods
- loose balls or other spherical bodies
- expanded/stretched/metal packages
- iron network packages
Resulting from their filigree structure, the last
named packing materials, namely:
- balls
- expanded metals
..
- iron network packings
are highly suitable for the enrichment of particularly weak
magnetic materials and/or particles with particularly fine grain
structure, for, in the case of a great number of induction poles
positioned at a small distance, even the smallest par-ticles being
present with the smallest number have the possibility to get
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within the region of high magnetic forces and to get held back.
On the other hand, it is difficult, if not impossible,
to wash out these particles by means of the usual cleaning of the
matrix carried out with a forceful water jet, for the dense pack-
ages of balls, expanded metal, and similar will break the flow
of the cleaning medium, and they let it through the space between
the great number of induction poles only at a very low rate, and
quasi without any energy. In this manner, the cleaning of the
matrix will be incomplete, for the jet-energy of the incompres-
sible cleaning fluid de_reases with the distance from the noæzle,
and as a result, it will only be efficient at the peripheral zones
of the induction pole, while within the deeper laying regions,
it will be broken by the filter-like packages of the induction
poles and become inefficient.
Also, the attempt to eliminate this drawback by using
larger amounts of liquid gave a moderate result, and even this
maderate result was associated with the following drawbacks:
1. A larger path-time portion, associated with
a corresponding decrease in throughput power
of the separator, is required for the clean-
ing, and
2, the large Liquid volumes made it necessary
to use more expensive clarifying and separating
apparatus in order to separate the obtained
solid material from the cleaning liquid.
The present invention proposes to eliminate the
drawbacks of the known processes for washing out the magnetic
separation space of hold-back separators and to obtain, in an
economical manner, both qualitative and quantitative improvement
in the operation of magnetic separators working on the h~ld-back
principle.
The above is resolved by using a compressible medium
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as an additional cleaning medium. When flowing through the matrix,
the compressible medium, advantageously oil-free compressed air,
undergoes a drop in pressure which is substantially lower than
that of the liquid, and - when expanding - it conveys a portion
of its energy to the liquid. As a result, the liquid intrudes
intensively the interspace between the induction poles. In this
proaess, a much better and much quicker cleaning effect is ob-
tained than that in the known washing processes utilizing liquid
alone.
In a preferred embodiment of the process according to
the present invention, the cleaning was carried out with a mixture
of a liquid and a gaseous media.
In this process, a method consisting of applying the
compressible medium at elevated pressure through the matrix
may also be used.
The process may advantageously also be modified in
such a manner that both media be used with a shift in phase.
For example, the introduction of the compressible med-
ium can be carried out somewhat after the liquid has been intro-
~0 duced and it can even be contimled after the fluid medium has
already been stopped.
In this case, and in accordance with the invention,
one can proceed in such a manner that the phases shifted in time
be at least partially overlapped.
It may also be expedient to form the cleaning process
in such a manner that the duration of the phases be different
from each other. For example, at the end of the washing process
with the liquid, an impulse of short dura-tion with compressed
air may result in the effect required.
However, the:duration of the compressed air introduc-
tion may be both longer or shorter than that of the liquid.
How the details of the process in the invention should
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be modified in order to obtain the optimum cleaning of the
matrix of a hold-bacX separator remain, in accordance with the
separation requirements present, to the discretion of the
specialist.
Furthermore, an improvement is obtainable in the pro-
cess according to the invention by introducing the compressible
medium under pulsating pressure. In this process, it may also
be advantageous to introduce additional vibrations to the matrix
during cleaning.
An apparatus for carrying out the process comprises
an entry chamber, attached mostly sealed to the entry end of
the matrix which has attachments for introducing the cleaning
media.
In a preferred embodiment of this apparatus, the
entry chamber is provided with a slider which provides for a
sealed connection between the stationary entry chamber and
movable matrix.
Furthermore, for the operation of the apparatus, a
process may also be advantageously used in which the entry
chamber moves together with the movable matrix during the
washing process, the entry chamber being lifted from the matrix
at the end of the washing process, and being brought back into
th~ initial position.
In this process a technique may be used in which the
mo-tions o the entry chamber and the matrix are automatically
controlled according to a function program and in accordance
with the operation of the control elements for the washing
media.
In accordance with a further aspect of the present
invention, there is provided a method for cleaning magnetic
material from the matrix of a magnetic separator, said matrix
being cleaned with a fluid and, additionally, with a compress~
ible medium, characterized in that each o the two media is used
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in chronological phase displacement, the ~luid medium being
applied first.
In accordance with a further aspect of the present
invention, there is provided a method for cleaning of magnetic
material retained by a ferromagnet matrix of a magnetic separa-
tor comprising the steps of cleaning the matrix to wash free
the magnetic material in a high pressure rinse, said cleaning
including the steps of first introducing a liquid medium into
a cleaning chamber and then separately introducing at a later
time a compressed gaseous medium under high pressure and without
prior mixing with the liquid medium directly into the cleaning
chamber lying in sealed relationship directly above the matrix
such that the liquid passing downwardly through the matrix
receives additional kinetic energy as a result of the introduc-
tion of the high pressure gaseous medium.
In accordance with a further aspect of the present
invention, there is provided a method for cyclically cleaning
ma~netic material retained by a ferromagnetie matrix during
rotation of a rotatable magnetic separator comprising the steps
o~: providing a charging chamber for sealed attachment to the
rotating separation chamber containing the matrix: and separately
introducing a liquid eleaning medium for cleaning into a top oE
~e char~ing chamber and separately introducing a gaseous medium
into the top of the eharging chamber w~len the liquid medium is
p~esent.
In accordance with a further aspect of the present
invention, there is provided an apparatus for separating magnetic
material, comprising: a separating chamber having a ferromagne-
tic matrix associated therewith for attracting magnetic material;
a charging chamber connected in gas sealing fashion directly to
a charging side of the separating chamber and matrix, means
connected directly to the charging chamber for the separate
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introduction of a liquid medium and the separate introduction
of a compressed gaseous medium directly into the charging
chamber without prior mixing.
In drawings which illustrate preferred embodiments
of the present invention:
Figure 1 is a plan view of one embodiment of a
magnetic separator according to the present
invention, and
Figure 2 is a cross-section of a further embod:iment
of a magnetic separator in the same category,
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as well as a matrix with applied entry
chamber.
The magnetic separator in Figure 1 comprises two pairs
of magnetic poles (1-2, 3-4) in the "S-~" - "N-S" arrangement.
Between the pairs of magnetic poles 1-2 and 3-4, a
ring-shaped sludge tank arrangement rotates in the direction of
arrow R. The tank arrangement 5 is subdivided into cell-like
separation spaces 5', 5". As shown as an example, these cells
are filled up with packages of ferromagnetic bodies 13. It is
such an individual cell 5', 5`' filled up with ferromagnetic bod-
ies that is termed as a "matrix". The ferromagnetic bodies form-
ing the induction poles may be, e.g., grooved plates, or spheri-
cal, ball-shaped or other loose, filling bodies or, as also
known, fillings consisting of stretched metal, iron network,
etc.
Reference numerals 6 and 6` designate the two entry
stations in which the material to be treated, along with the
fluid carrier medium,is introduced into matrix 5`, 5" as the
latter is being moved along. Entry stations 6, 6` are always
within the entry region of a magnetic field present between one
of the pairs of magnetic poles 1-2, 3-4. At the exit region
of the magnetic field, stations 7, 7' are pro~ided for washing
at medium pressure, while outside the magnetic ~ield washing
stations 8, 8` are positioned in which the magneticmaterial hold
back in separation spaces 5`, 5" of the matrix is cleaned com-
pletely. Each of stations 8, 8` for high pressure cleaning are
provided with a connection 9 for the fluid cleaning medium and
with a connection 10 for the compressible medium.
Figure 2 shows a magnetic separator of the same func-
tion class, in cross-section. In Figure 2, magnetic poles 1,2 -
corresponding to "S-~" - are provided with magnetizing winding
11. Tank arrangement 5 rotates about rotational axis 12 between
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magnetic poles 1, 2. As seen, one individual matrix 5" is filled
up with magnetic bodies 13. Downward, matrix 5" is closed with
porous bottom part 14. selow it, recipient 15 is located in
which the cleaned material is collected.
Entry chambers 16 are positioned above matrix 5" into
which one connection 17 discharges the fluid cleaning medium and
one connection, the compressible medium. setween matrix 5" and
entry chamber 16 is located a slider 19 serving-as a sealing ele-
ment, the slider 19 providing a sealed connection between the
stationary entry chamber 16 and the movable separating space S"
of the matrix. The slider, via entry chamber 16 is elastically
pressed against the upper edge of matrix 5" by means of spring
arrangement 20.
The apparatus operates in the following manner: between
each pair of poles 1-2, 3-4 '`South-North/North-South" correspond-
ingly, which generates a strong magnetic field, rotates indivi-
dual cell-like separation spaces 5', 5" which, in turn, as a
magnetic induction pole, is provided with a filling or package
of ferromagnetic bodies 13, termed as matrix. In accordance
with the state of art, grooved plates, loose balls or other
loose bodies made of magnetizable iron, as well as packages of
stretch metal, ironwool, etc., may be used as such ferromagnetic
bodies 13. Tank arrangement 5 rotates in the direction of arrow
R and is driven, at approximately constant speed, by a driving
mechanism, not illustrated in the drawing.
When matrix 5" enters one of the magnetic fields be-
tween poles 1-2, 3-4, it will simultaneously come within the
region of one of the two entry stations 6, 6' and it will, toget-
her with the material to be separated, be acted upon by a sus-
pension of magnetic and non-magnetic particles in a carrying-
liquid. In this process, the bulk of the non-magnetic particles
will be washed away through the matrix into the outElow, while
624
the magnetically susceptible particles, as magnetic material,
will be held back on the ferromagnetic bodies in the internal
of the matrix. Shortly before coming out of the magnetic field,
the matrix passes through station 7, or 7' for washing at medium
pressure. Here, the magnetic concentrate will be washed free
from the attached non-magnetic particles and sometimes, depend-
ing on the energy of the cleaning process, an intermediate pro-
duct will be removed as a magnetic material.
After rotating out of the region of one o the magnetic
fiel~ completely, matrix 5', 5" arrives at one o~ stations 8, 8'
for washing at high pressure. Here, the magnetic material held
back by the separator will be washed out of the matrix by means
of a liquid cleaning medium and - in accordance with the inven-
tion - additionally by a compressible medium at elevated pres-
sure. The liquid or compressible cleaning media will flow out
of the input chamber, positioned tightly at the upper edge of
the matrix, - either simultaneously or subsequently, and at
elevated pressure - through the package of ferromagnetic bodies
and will clean their interspaces rapidly and thoroughly from the
magnetic material attached.
The non-expected effect of the invention is based on
the fact that the compressible medium expands toward the bottom
14 of the separation space of the matrix, thereby carrying over
at least the main part of the kinetic energy set free to the
fluid cleaning medium existing in the spaces between the ferro-
magnetic bodies. In this manner, the cleaning process will be
` `intensified to an unusual extent, and will be reduced in time,
and - as experiments have shown - an incomparably better clean-
ing is obtained in a shorter time than that which has been
possible,to date utilizing exclusively a fluid medium, particular-
ly when the structure of the matrix is dense~
In this process, as it has already been mentioned
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above, it remains to the average specialist to coordinate the
pressure conditions of both cleaning media, as well as the dura-
tion of their application, to each other in an optimum manner.
In some cases, excellent results have already been obtained when,
at the end of the cleaning process with the fluid medium a short
and sometimes pulsating pressure impulse of the compressible med-
ium, i.e., oil-free compressed air, was applied. In addition,
it was also found in these experiments that the introduction of
compressed air of pulsating pressure results in a particularly
good and unexpectedly efficient cleaning effect. Other experi-
ments in which it was the matrix that obtained vibrations during
the cleaning process led also to unexpectedly good results.
A particular advantage of the process, as well as the
apparatus, according to the present invention, consists of the
fact that, in the case of a magnetic separator of corresponding
type which is already present, it may be additionally carried
out or applied as a supplementary improvement. In the case of
old magnetic separator plants, it becomes possible to obtain a
substantial rationalization effect at relatively low costs by
way of increasing the operation results both qualitatively and
quantitatively.
~ either the process nor the apparatus according to the
invention is restricted to the preferred embodiments shown in
the drawings and described above. The same could be modified
and optimalized according to existing apparatus or work-shop
or technical conditions and still come within the scope of the
present invention,so long as they satisfy one of the following
claims.
