GB1598557A - Method and device for cleaning off the matrix of a magnetic separator - Google Patents

Description

(54) A METHOD AND A DEVICE FOR CLEANING OFF THE MATRIX OF A MAGNETIC SEPARATOR (71) We, KLocKNER-HUMBoLDT- DEUTE AKTIENGESELLSCHAFT of Deutz Mulheimer-Strasse 111, 5 Koln 80, Federal Republic of Germany, a German Body Corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the fol lowing statement: The invention relates to a method of cleaning off the matrix of a magnetic separator whereby the matrix is cleaned off by a liquid medium.

Magnetic separators operating according to the principle of retaining material are normally made use of in order to handle relatively large throughput quantities, for example in the region of 20 to 200 tonnes per hour and are moreover suited particularly to grading weakly magnetic minerals. The mode of operation of these wet magnetic retention separators is characterized by the fact that the highest possible magnetic field is produced in a certain operating volume, the socalled separating chamber inside a coil. Induction poles are located inside this operating volume in the form of suitable magnetizable ferromagnetic bodies which distort the magnet field as a result of their high permeability such that considerable inhomogeneity arises and thus the required gradients are produced at a plurality of preferred points in the volume of the separating chamber.The arrangement of the ferromagnetic body in an appropriate separating chamber is called the "matrix".

When passing the slurry laden with susceptible particles through the matrix, the magnetic material contained in the slurry is held back by the ferromagnetic bodies as a result of the high local magnetic forces. This material held back is then normally rinsed out of the matrix with a strong jet of water.

This takes place in discontinuously or batch operating separators in the following manner: the magnetic field is switched off periodically and the magnetic material is rinsed out of the matrix in the switched off state. However in practice continuously operating separators are coming more and more to the fore, such as the Jones separator or the carousel separator.

In these continuously operating separators the magnetic material is moved out of the magnetic field and washed out together with the matrix, and the cleaned matrix is ready again for the next passage through the magnetic field. According to the type of magnetic material, it may be necessary moreover for the magnetic material to be cleaned of adhering non-magnetic proportions of material by means of a washing process in the region of the magnetic field.

Moreover, there is often the necessity of obtaining middlings. This takes place also by rinsing out at reduced rinsing energy a part of the magnetic material having the tailings sticking to it, still inside the magnetic field.

In practice the following are used as induction poles: Plates having projecting edges Profiled rods Loose spheres or other loose sperical bodies Expanded metal briquettes Iron mesh. packing materials The last-mentioned filling bodies: Spheres Expanded metal Iron mesh are decidedly well suited to enriching particularly weak magnetic materials and/or particles having a particularly fine grain structure, owing to their filigree structure, because, with a plurality of indiction poles at a small spacing, even the smallest particles arising in a small number have the opportunity of being held back and arriving in a region of higher magnetic force.

On the other hand, however, rinsing out these particles by means of normal cleaning of the matrix is difficult with a strong jet of water, if not even impossible, because the tight packing of spheres, expanded metal and the like breaks up the flow of the cleaning medium and only lets it through at a low speed almost without energy through the spaces between. the plurality of induction poles. In this way cleaning of the matrix remains incomplete because the jet energy of the incompressible cleaning liquid reduces with the distance from the jet and, as a result, is only effective at the edge regions of the induction poles, while in the deeper regions, this energy is broken up by the filter-like packing of the induction poles and is thus made ineffective.

Even the attempt to compensate for this advantage by using large quantities of liquid brought little success and moreover was paid dearly for with the following disadvantages: 1. A large proportion of distance time is used for cleaning with the correspondence reduction in the throughput of the separator is necessary and 2. The large quantities of liquid make for more expensive clarifying and separating apparatus necessary in order to separate the solid obtained from the cleaning liquid.

The invention seeks to overcome the disadvantages of the known method in order to rinse out magnetic separating chambers in retention separators and thus to achieve both a qualitative and quantitative improvement in the mode of operation of these magnetic separators operating according to the retention principle in an economical manner.

According to the invention, there is provided a method of cleaning the matrix of a magnetic separator comprising using both a liquid medium and a compressible medium under elevated pressure as the cleaning media, the use of the two being out of phase but overlapping at least partially.

Preferably the liquid medium is used first.

The compressible medium, preferably oilfree compressed air, experiences a substantially lower fall in pressure when passing through the matrix than the liquid and transmits a part of its kinetic energy, during its expansion, to the liquid which, as a result intensively penetrates the intermediate chambers of the induction poles. Thus a substantially better and faster cleaning effect takes place than in the known rinsing process using only liquid.

In an advantageous refinement of the method, cleaning off may be carried out, for example, with a mixture of liquid and gaseous media.

Thus, moreover, use may be made of the measure according to which the pressure of the compressible medium is greater than the pressure of the liquid medium.

For example feed of the compressible medium may take place some time after feed of the liquid and in some cases it may be continued after the liquid medium has already been cut off.

Of course, the time-shifted phases overlap at least partially.

It may also be advisable to design the cleaning process so that the duration of the phases is of a different length. For example, a short compressed air surge towards the end of the liquid rinsing process may achieve the desired effect.

Addition of compressed gas may be longer or shorter however than addition of liquid.

It is left to the expert's judgement, in accordance with the requirements for dressing present in each case, as to the details of modification of the method according to the invention for the purpose of optimizing cleaning of the matrix of a retention separator.

The liquid medium and the compressible medium may be fed to a feed chamber in engagement with the feed side of the matrix through a slide element so as to seal it off.

The invention wili now be described in greater detail, by way of example, with reference to the drawings in which: Figure 1 shows in plan view, a magnetic separator to which the method in accordance with the invention can be applied, and Figure 2 shows another magnetic separator in the same category as well as a matrix with a feed chamber set thereon and in section.

The magnetic separator according to Figure 1 has two magnet pole pairs with four magnet poles (1-2; 34) in "S "N-S" arrangement.

A circular container arrangement 5 rotates between the pairs of magnet poles 1-2; 34 in the direction of the arrow R. This container arrangement 5 is subdivided into cell-like separated chambers 5'; 5". As has been shown in an exemplary manner, these are filled with packing material of ferromagnetic bodies 13.

This type of individual cell 5'; 5" filled with ferromagnetic bodies is called a "matrix". In the ferromagnetic bodies forming the induction poles, it is a question, for example, of grooved plates or spherical, ball-shaped or other loose filling bodies, or, as already known, it is a question of fillings made of expanded metal, iron mesh etc. Two feed stations are designated 6 and 6', in which the material to be treated is fed intoAhe passing matrix 5', 5" with its liquid carrier medium. The feed stations 6, 6' are located in each case in the entry region of a magnetic field prevailing between one of the magnet pole pairs 1-2; 34.At the outlet region from the magnetic field are provided stations 7, 7', in each case for medium pressure rinsing, and finally the rinsing stations 8, 8' can be seen outside the magnetic fields, in which rinsing stations the complete cleaning of the magnetic material retainedin the separating chambers 5', 5" of the matrix takes place. The stations 8, 8' for high-pressure rinsing each have a connection 9 for the liquid cleaning medium and each have a connection 10 for the compressible medium.

Figure 2 shows a magnet separator of the same function type in section.

The magnet poles 1,2 corresponding to "S N" can be seen with the energizing windings 11.

The container arrangement 5 rotates around the axis of rotation 12 between these magnet poles 1,2. The filling of one individual matrix 5 with the ferromagnetic bodies 13 can be seen.

The matrix 5" is closed below by a porous base 14. Below it is located the collecting channel 15 in which the rinsed out material collects.

The feed chamber 16, into which opens a connection 17 in each case for the liquid cleaning medium and a connection 18 for a compressible medium, is located above the maxtrix 5". A slide element 19 is located between the matrix 5" and the feed chamber 16 as a sealing element; it makes the sealed connection between the fixed feed chamber 16 and the movable separating chamber 5", of the matrix. The slide element is pressed resiliently against the upper edge of the matrix 5 ' from across the feed chamber 16, by means of a spring arrangement 20.

The operation of the arrangement is as follows: The container arrangement 5 rotates continuously between every two pole pairs 1-2; 34; corresponding to "South-North/North-South", these pole pairs producing a strong magnetic field between them. This container arrangement S is subdivided into individual cell-like separating chambers 5', 5", these having a filling or packing of ferromagnetic bodies 13 in turn as magnetic induction poles, and this is called a matrix. In accordance with the state of the art these ferromagnetic bodies 13 can be grooved plates, loose balls or other loose bodies for example, made of soft magnetic iron or packing materials made of expanded metal, steel wool etc. The container arrangement 5 rotates in the direction of the arrow R driven at approximately constant speed by a drive arrangement not shown in greater detail.When a matrix 5" enters one of the magnetic fields between the poles 1-2; 34, then the latter arrives at the same time in the region of one of the two feed stations 6, 6' and is acted upon by the material to be separated, a suspension of magnetic and non-magnetic particles in a carrier liquid. Thus the majority of the non-magnetic part is rinsed through the matrix as pairings, while the magnetically susceptible particles are held back as a magnetic material by the ferromagnetic bodies inside the matrix. Shortly before the outlet from the magnetic field the matrix passes station 7 or 7' for medium pressure rinsing. The magnetic concentrate is washed clear of the non-magnetic material sticking to it there are - according to the energy of the cleaning process - in some cases magnetic middlings may be extracted.

After complete movement of a matrix 5', 5" out of the region of one of the magnetic fields the matrix reaches one of the stations 8, 8' for high-pressure rinsing.

The magnetic material caught by the separator is rinsed out of the matrix by means of a liquid and additionally by means of a compressible cleaning medium at increased pressure.

Liquid and compressible cleaning medium respectively flow in an at least partially overlapping manner, at increased pressure out of the feed chamber, bearing onthe upper edge of the matrix so as to form a seal, through the packing of the ferromagnetic bodies and rapidly and thoroughly cleans its intermediate chambers of the magnetic material sticking to them.

The surprising effect of the invention rests on the fact that the compressible medium ex pands towards the lower side 14 of the separ ating chamber of the matrix and thus the kinetic energy released is transmitted at least for the most part to the liquid cleaning medium located in the spaces between the ferromagnetic bodies. As a result, the cleaning process is intensified in an unusual manner and is also shortened in terms of time. As tests have shown, a much better cleaning process occurs in a shorter time than was possible previously with exclusive use of a liquid cleaning medium, particularly with a dense structure of the matrix.

Thus as has already been mentioned above, it is the technical expert's task to decide on the optimum pressure ratios of both rinsing media as well as the duration of their use.

In some cases, this has led to excellent results when a short and possibly pulsating pressure surge in the compressible medium, i.e. with oil-free compressed air, is used at the end of the rinsing process with a liquid rinsing medium.

In these tests, it has been proved moreover that the addition of compressed air at pulsating pressure brought about a particularly good and surprisingly effective cleaning effect.

Other tests in which oscillations were introduced into the matrix during the rinsing process also brought surprisingly good results.

A particular advantage of the method as above described and of the corresponding device is moreover founded on the fact that the method can be carried out and the apparatus arranged in an existing magnetic separator of the appropriate type subsequently, as an additional improvement. As a result, it is possible to achieve a considerable rationalization effect at relatively low cost in fairly old magnetic separator systems by qualitatively and quantitatively increasing the results of operation.

WHAT WE CLAIM IS: 1. A method of cleaning the matrix of a magnetic separator comprising using both a liquid medium and a compressible medium under elevated pressure as the cleaning media, the use of the two being out of phase but overlapping at least partially.

2. A method according to Claim 1, wherein the liquid medium is used first.

3. A method according to Claim 1 or 2 wherein the pressure of the compressible medium is greater than the pressure of the liquid medium.

4. A method according to Claim 1,2 or 3, wherein each of the two media come into use for different time periods.

5. A method according to Claim 3 or 4, wherein the duration of the phases is of different length.

6. A method according to any one of Claims 1 to 5, wherein the liquid medium and the com- pressible medium are fed into a feed chamber in engagement with the feed side of the matrix through a slide element so as to seal it off.

7. A method of cleaning the matrix of a magnetic separator substantially as described

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. 5". A slide element 19 is located between the matrix 5" and the feed chamber 16 as a sealing element; it makes the sealed connection between the fixed feed chamber 16 and the movable separating chamber 5", of the matrix. The slide element is pressed resiliently against the upper edge of the matrix 5 ' from across the feed chamber 16, by means of a spring arrangement 20. The operation of the arrangement is as follows: The container arrangement 5 rotates continuously between every two pole pairs 1-2; 34; corresponding to "South-North/North-South", these pole pairs producing a strong magnetic field between them. This container arrangement S is subdivided into individual cell-like separating chambers 5', 5", these having a filling or packing of ferromagnetic bodies 13 in turn as magnetic induction poles, and this is called a matrix. In accordance with the state of the art these ferromagnetic bodies 13 can be grooved plates, loose balls or other loose bodies for example, made of soft magnetic iron or packing materials made of expanded metal, steel wool etc. The container arrangement 5 rotates in the direction of the arrow R driven at approximately constant speed by a drive arrangement not shown in greater detail.When a matrix 5" enters one of the magnetic fields between the poles 1-2; 34, then the latter arrives at the same time in the region of one of the two feed stations 6, 6' and is acted upon by the material to be separated, a suspension of magnetic and non-magnetic particles in a carrier liquid. Thus the majority of the non-magnetic part is rinsed through the matrix as pairings, while the magnetically susceptible particles are held back as a magnetic material by the ferromagnetic bodies inside the matrix. Shortly before the outlet from the magnetic field the matrix passes station 7 or 7' for medium pressure rinsing. The magnetic concentrate is washed clear of the non-magnetic material sticking to it there are - according to the energy of the cleaning process - in some cases magnetic middlings may be extracted. After complete movement of a matrix 5', 5" out of the region of one of the magnetic fields the matrix reaches one of the stations 8, 8' for high-pressure rinsing. The magnetic material caught by the separator is rinsed out of the matrix by means of a liquid and additionally by means of a compressible cleaning medium at increased pressure. Liquid and compressible cleaning medium respectively flow in an at least partially overlapping manner, at increased pressure out of the feed chamber, bearing onthe upper edge of the matrix so as to form a seal, through the packing of the ferromagnetic bodies and rapidly and thoroughly cleans its intermediate chambers of the magnetic material sticking to them. The surprising effect of the invention rests on the fact that the compressible medium ex pands towards the lower side 14 of the separ ating chamber of the matrix and thus the kinetic energy released is transmitted at least for the most part to the liquid cleaning medium located in the spaces between the ferromagnetic bodies. As a result, the cleaning process is intensified in an unusual manner and is also shortened in terms of time. As tests have shown, a much better cleaning process occurs in a shorter time than was possible previously with exclusive use of a liquid cleaning medium, particularly with a dense structure of the matrix. Thus as has already been mentioned above, it is the technical expert's task to decide on the optimum pressure ratios of both rinsing media as well as the duration of their use. In some cases, this has led to excellent results when a short and possibly pulsating pressure surge in the compressible medium, i.e. with oil-free compressed air, is used at the end of the rinsing process with a liquid rinsing medium. In these tests, it has been proved moreover that the addition of compressed air at pulsating pressure brought about a particularly good and surprisingly effective cleaning effect. Other tests in which oscillations were introduced into the matrix during the rinsing process also brought surprisingly good results. A particular advantage of the method as above described and of the corresponding device is moreover founded on the fact that the method can be carried out and the apparatus arranged in an existing magnetic separator of the appropriate type subsequently, as an additional improvement. As a result, it is possible to achieve a considerable rationalization effect at relatively low cost in fairly old magnetic separator systems by qualitatively and quantitatively increasing the results of operation. WHAT WE CLAIM IS:

1. A method of cleaning the matrix of a magnetic separator comprising using both a liquid medium and a compressible medium under elevated pressure as the cleaning media, the use of the two being out of phase but overlapping at least partially.

2. A method according to Claim 1, wherein the liquid medium is used first.

3. A method according to Claim 1 or 2 wherein the pressure of the compressible medium is greater than the pressure of the liquid medium.

4. A method according to Claim 1,2 or 3, wherein each of the two media come into use for different time periods.

5. A method according to Claim 3 or 4, wherein the duration of the phases is of different length.

6. A method according to any one of Claims 1 to 5, wherein the liquid medium and the com- pressible medium are fed into a feed chamber in engagement with the feed side of the matrix through a slide element so as to seal it off.

7. A method of cleaning the matrix of a magnetic separator substantially as described

herein with reference to the drawings.