GB2076699A - A method and an apparatus for cleaning the matrix of a magnetic separator - Google Patents

Abstract

A method of cleaning the matrix 5 of a magnetic separator of attracted magnetic material comprises cleaning the matrix in a neutral region outside the magnetic field 1-2, 3-4 in at least two successive stages 8,9,8',9'. Different cleaning agents, e.g. water, compressed air, or different quantities or pressures thereof may be used in the different stages for optimum cleaning. A continuous rotating arrangement of matrices 5',5'' is shown. <IMAGE>

Description

SPECIFICATION A method and an apparatus for cleaning the matrix of a magnetic separator The invention relates to a method and apparatus for cleaning the matrix of a magnetic separator of attracted magnetic material when the matrix is outside the magnetic field.

The difficulty in cleaning the matrix of a magnetic separator operating on the principle of retaining a residue increases the smaller the passage ways between the ferro-magnetic elements which form the matrix and the smaller the grain spectrum of the solid particles, for example of slurries comprising ore, and the higher the proportion of cohesive components in the pulp.

Another factor is that the induction poles have a certain magnetic remanence when types of ferrous metal are used which are not entirely weak magnetically and this remanence provides forces which counteract the process of removing the attracted material.

Once a matrix has been guided out of the magnetic field, the attracted magnetic material is usually rinsed out in the so-called neutral region using a cleaning agent.

This rinsing process, which is a process of cleaning off attracted material from the matrix, is all the more difficult to implement the closer the packing of the induction poles in the matrix. This is because the packing provides a number of obstacles to the jet of any cleaning agent as a result of which the jet energy falls rapidly and is unable to have any satisfactory cleaning effect in deeper areas of the matrix.

The suggestion has already been made that a compressible medium should be used in addition to a liquid medium for the purpose of cleaning magnetic material from the matrix of a magnetic separator, the matrix being primarily cleaned with the liquid medium. In this case, either simultaneously or successively, liquid and gaseous cleaning agents flow out of a feed chamber, abutting the upper edge of the matrix so as to provide a seal, at an elevated pressure through the packing of the ferro-magnetic elements and thoroughly clean the intermediate spaces of any magnetic material sticking thereto (German Auslegeschrift 26 50 925).

The invention seeks to modify and improve on known methods and apparatus for cleaning the matrix of a magnetic separator.

To this end it is desired to achieve a method and apparatus which make it possible for the cleaning intensity to be adapted flexibly to an optimum extent to all of the levels of difficulty which occur in practice. In order to achieve this optimum situation, after each level of difficulty has been determined, only that amount of cleaning agent and that quantity of cleaning energy is used which is in fact required in order to ensure that the magnetic separator continues to operate correctly.

According to a first aspect of the invention, there is provided a method of cleaning the matrix of a magnetic separator of attracted magnetic material in a location outside the magnetic field, wherein the attracted magnetic material is cleaned off from the matrix in a neutral region in at least two successive stages.

The invention has the advantage of being able to clear away a fair proportion of the attracted magnetic material without difficulty in the first stage, as seen in the direction of movement of the matrix, the only material not yet removed remaining because of the special difficulties which have been described. This residue of attracted magnetic material which is difficult to remove is however much easier to clear away in the second cleaning stage, because of the extensive initial cleaning of the matrix in the first stage, than was the case when there was only a single stage. The method also has the advantage of being uncomplicated. The same cleaning agent may be used in the various stages, if necessary in different quantities and at different pressures.

The advantage of this measure is that the first stage may be operated with a slightly larger quantity of cleaning agent for example under slightly lower pressure and the second stage may be operated with a smaller quantity of cleaning agent under a slightly higher pressure which results in an optimum cleaning action and at the same time economic use of cleaning agent and energy.

Different cleaning agents may be used in the stages.

This means that a liquid cleaning agent may be used in a first stage, for example, and a gaseous cleaning agent may be used in a second stage.

However it is also possible for water to be used in a first stage and water and air to be used in a second stage as cleaning agents.

Given the wide variety of possible embodiments, then depending on the degree of difficulty in each case the method may be adapted flexibly to each individual case.

Thus, at least one cleaning station may be operated continuously and while another cleaning station may be operated intermittently.

This provision take optimum account of those cases in which dirt periodically adheres to the inside of the matrix in such a manner as to disrupt continuous operation of the magnetic separator and the fact that the cleaning intensity of the first stage would be sufficient most of the time to ensure satisfactory operation. The method therefore manages to reduce the problem of achieving optimum efficiency of the cleaning off process, economic use of energy, and low costs, to a common denominator.

According to a second aspect of the invention, there is provided apparatus for cleaning the matrix of a magnetic separator of attracted magnetic material in a location outside the magnetic field, wherein at least two cleaning stations are provided in a neutral region for cleaning the attracted magnetic material from the matrix in two successive stages. Each of these stations may be equipped with means for the supply of at least one cleaning agent and with means for collecting the magnetic material which has been removed during the cleaning process.

Apart from the chief advantage that such an arrangement is uncomplicated and efficient there is a further advantage of being able to fit the apparatus to magnetic separators which are already in operation and thus eliminate any cleaning problems in an uncomplicated fashion.

The second cleaning station, as seen in the direction of movement, may have a stationary feed chamber adjoining the feed side of the matrix, this feed chamber being in approximately pressuretight connection with the matrix via a sliding seal.

This arrangement, known per se from German Offenlegungsschrift 26 50 925 which has already been mentioned above, makes it easy to pass any desired cleaning agents through the matrix at an elevated pressure and thus to optimise the cleaning process easily.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 shows a magnetic separator operating by the residue techniques in plan view having cleaning stations in accordance with the invention.

Figure 2 shows an operational plan of the apparatus in accordance with the invention for a magnetic separator, the plan being shown as a block circuit diagram.

A circular container arrangement 5 rotates between pairs of magnet poles 1--2; 3--4 in the direction of the arrow R. The container arrangement 5 is sub-divided into cell-like compartments forming individual matrices 5', 5".

These compartments are equipped with a packing 13 comprising ferro-magnetic elements as is shown purely schematically in the drawings. The ferro-magnetic elements, which form the induction poles, may be grooved plates or spherical, ball-like or other similar filling elements or, as is also known, the filling may comprise expanded metal, iron meshing, ironwool etc. Feed stations associated with each pole pair 1--2; 3--4 are designated 6, 6' and in these the material which is to be treated, for example a pulp containing particles of ore, is fed into the matrices 5', 5" as they pass.These feed stations 6, 6' are located in each case in the inlet region of a magnetic field formed between one of the pairs of magnetic poles 1-2; 3-4. The stations 7, 7' respectively, which carry out pressure rinsing with an agent, are provided in the outlet region of each magnetic field and the non-magnetic material adhering to the attracted magnetic material is washed clean by means of these stations. If necessary, weakly magnetic middlings are also rinsed away at these stations. Outside the magnetic fields, in the socalled neutral region, approximately equally spaced between the magnetic pole pairs 1-2; 3-4 are arranged two cleaning stations 8, 9; 8', 9' respectively.The first station 8, 8' as seen in the direction of rotation in accordance with the directional arrow R has a connection 10, 10' for the supply of a cleaning agent. In this example the first cleaning station 8, 8' is operated continuously using water as the cleaning agent. The second station 9, 9', as seen in the direction of rotation has two supply lines 11, 12; 1 1', 12' for two different cleaning agents. In this example, the supply lines 11, 11' are provided for the supply of water and the supply lines 12, 12' are provided for the supply of compressed air.

Operation of the arrangement is as follows: The container arrangement 5 rotates continuously in the direction of the arrow R between the two pole pairs 1-2; 3-4 respectively corresponding to South/North North/South, which produce a strong magnetic field between them. The container is sub-divided into individual cell-like compartments 5', 5 which constitute a sequence of matrices because of their being filled in each case with a variety of ferro magnetic poles.When a matrix 5', 5 enters one of the magnetic fields between the poles 1-2; 3-4, then straight away it enters the region of one of the feed stations 6, 6' and is fed with the material which is to be treated, for example a suspension of magnetic and non-magnetic particles.

Thus, for the most part non-magnetic material is rinsed through the matrix, while magnetic material is retained on the ferro-magnetic induction poles of the matrix. Before it passes out of the magnetic field each matrix passes a station 7 or 7' which carries out rinsing under pressure with rinsing agent and washes the attracted magnetic material. The magnetic concentrate held back in the matrix is cleared of non-magnetic material adhering to it and, depending on the energy set for this particular cleaning process, magnetic middlings may be extracted as an intermediate product.

On further rotation in the direction of arrow R, a matrix 5t, 5 reaches the so-called neutral region approximately at an equal distance from the pairs of magnet poles 1-2; 3-4 and in this region there is no longer any magnetic field. The matrix 5', 5" first of all reaches one of the first cleaning stations 8, 8' in this neutral region. The greater part of the attracted magnetic material adhering to the matrix is cleaned off in this station by means of intensive rinsing with water, and the extracted product is collected.

However in the case of very fine material with a cohesive component and with ferro-magnetic elements in the matrix which have a filigree structure there is a residue left in the matrix which has not been cleaned off. It is the object of the second cleaning station 9, 9' to act on this residue and ultimately clear it away. A liquid and/or a compressible cleaning agent pass out of this second cleaning station, either at the same time or in succession, a flow through the packing 1 3 comprising the ferro-magnetic elements and clear the intermediate spaces rapidly and thoroughly of the residue of magnetic material adhering thereto.

This is because the second cleaning process may have a considerably greater efficiency because the majority of the magnetic material has already been removed by the preceding cleaning process.

Figure 2 shows the magnetic separator system and its operation in the form of a schematic and operational flow diagram. The magnetic separator shown in plan view in Figure 1 should be imagined in the condition where the circular container arrangement 5 is cut at one point and pivoted into a straight line.

In Figure 2 the same elements have been provided with the same reference numerals for the sake of simplicity. The container arrangement 5 moves from left to right in the direction of the arrow R. Thus, first of all, one of the cell-like matrices 5' arrives at the supply station 6 in the region of the magnetic field 20, between poles which have not been shown for the sake of simplicity. The material which is to be separated is fed from the pulp supply paint 21 as indicated by the arrow 22. Non-magnetic material runs through the matrices 5' into a collecting arrangement 23.

As it passes the washing station 7, the magnetic material retained in the matrices 5' is subjected to a washing process with water, indicated by the arrow 24 and is therefore cleared of any nonmagnetic material adhering to it. At the same time a weakly magnetic material, so called middlings, is extracted and re-cycled by means of a pump 25 to the pulp feed 22 through the line 26. The matrices 5', still laden with the washed magnetic material, pass out of the magnetic field 20 into a so-called neutral region and reach the first cleaning station 8. This cleaning station 8 has a supply point 10 for a cleaning fluid, which rinses off a fair proportion of the attracted material, as it passes through a matrix 5', using powerful water jets for example and supplies the attracted material to a collecting device 27 for magnetic material.As it moves further, one of the matrices 5' reaches the second cleaning station 9 which also has a supply point 11 for a fluid cleaning agent. This cleaning fluid is raised to an elevated pressure level by a pressure increase pump 28, thus increasing the intensity of the cleaning process. The second cleaning station 9 also has a supply point 12 for compressed air which is fed from a compressed air source 29.

Whereas the first cleaning station 8 is operated continuously in the example shown, the second cleaning station 9 has a timer circuit which actuates the controi elements 33 and 34 at intervals of time which can be set as desired means of a timing element 30, the switch device 31 and the control lines 32, and this leads to intermittent operation of the second cleaning station 9 for example.

In the second cleaning station 9 there is also a feed chamber 35 which abuts the upper edge of each matrix 5' as it moves past in a manner so as to seal it, this feed chamber 35 ensuring that both the liquid and the compressible cleaning agent may be passed through the packing of the ferro magnetic elements at an elevated pressure.

The operating cycle which has been described above continues when the cleaned matrices 5" reenter the supply station 6', washing station 7', first cleaning station 8' and second cleaning station 9' and is repeated periodically.

The example shown and described merely constitute schematic embodiments of the invention. Similar refinements or modifications which lie within the expert's judgement, such as the arrangement of more than two cleaning stations for example, the design and sequence of supply devices for liquid or gaseous cleaning agents as well as their optional use in any desired sequence also fall within the invention.

Claims (12)

1. A method of cleaning the matrix of a magnetic separator of attracted magnetic material in a location outside the magnetic field, wherein the attracted magnetic material is cleaned off from the matrix in a neutral region in at least two successive stages.

2. A method according to Claim 1, wherein the same cleaning agents are used in these stages.

3. A method according to Claim 2, wherein the cleaning agents are used in different quantities and at different pressures.

4. A method according to Claim 1, wherein different cleaning agents are used in the stages.

5. A method according to Claim 4, wherein a liquid cleaning agent is used in a first stage and a gaseous cleaning agent is used in a second stage.

6. A method according to Claim 4, wherein water is used in a first stage and water and compressed air is used in a second stage as the cleaning agents.

7. A method according to any one of the preceding claims wherein at least one cleaning station is in operation continuously and one other cleaning stage is in operation intermittently.

8. Apparatus for cleaning the matrix of a magnetic separator of attracted magnetic material in a location outside the magnetic field, wherein at least two cleaning stations are provided in a neutral region for cleaning the attracted magnetic material from the matrix in two successive stages.

9. Apparatus according to Claim 8, wherein each of the cleaning stations is equipped with means for supplying at least one cleaning agent and with means for collecting the magnetic material which is removed during cleaning.

10. A magnetic separator according to Claim 8 S 9, wherein the second cleaning station i.e. the second station as seen in the direction of movement of the matrix, has a stationary feed chamber adjoining the feed side of the matrix, the stationary feed chamber being connected to the matrix approximately in pressure tight manner via a sliding seal.

11. A method of cleaning the matrix of a magnetic separator substantially as described herein with reference to the drawings.

12. A magnetic separator substantially as described herein with reference to the drawings.