SE434016B - MAGNETIC SEPARATOR FOR SEPARATION OF SOLID MAGNETIC PARTICLES FROM A SLIP - Google Patents

Description

15 20 25 30 35 40 7712967-4 the rotating drum is partially immersed in a slurry liquid.

Recently, a wet magnetic, high-intensity separator has been developed for wet separation and the most commercially successful is the so-called "Jones Separator". A typical embodiment of the Jones separator has been described in U.S. Patent No. 3,326,374, issued June 20, 1967, and is circularly formed with a series of vertically oriented, grooved plates arranged in a round ring which rotate horizontally through alternating magnetic fields. In this way, a magnetic field is introduced into the grooved plate sections as they pass a magnetic pole, whereupon they reach a point of field strength zero between the poles of opposite polarity and again a strong magnetic field at the next magnetic pole. A slurry is fed to the grooved plates in the area of a magnetic pole, so that magnetic particles stick to the walls of the plates. A water flushing device provides rinsing away of non-magnetic material, and then, at a location with low or no magnetic field strength, the magnetic particles are removed from the plates by water flushing under high pressure. The magnetic and non-magnetic particles are collected in separate gutters. The magnetic pole pieces are usually placed on opposite sides of the knurled plate sections, and to create strong magnetic fields, the magnetic pole pieces usually consist of electromagnets.

Such a flow through separators is thus provided with a horizontal rotor with a ring supported by a grooved plates, the rotor being rotatably mounted on a vertical axis. From a mechanical point of view, especially in the case of very large machines, the suspension bearings for such a vertical shaft pose a significant problem. If you do not ensure that all material is removed from the knurled plates during each cycle, there is also a tendency for some material to accumulate between the plates, thereby reducing the efficiency of the machine. Unless it is ensured that all separated particulate matter is below a certain minimum É particle size, e.g. less than 1 mm, other difficulties can also arise, since larger particles get stuck either on top of the grooved plate sections or between the plates. An attempt to overcome some of these problems is disclosed in U.S. Pat. No. 3,375,925, issued April 2, 1968. A number of loosely bonded, individually movable pole pieces are proposed, such as vertically oriented, helical rods or ball bearings. However, it has been found that these pole pieces already adhere to each other after a short period of time due to rust problems and coating accumulations, whereby the advantage of loose, unbound pole pieces is completely lost. Numerous attempts have also been made to provide a system in which a rotor is rotatably mounted in a vertical plane. Such a system is described in U.S. Patent 3,690,454, issued September 12, 1972. Here, too, soft iron balls are used as induction pole pieces, whereby these balls must be freely movable except when they are under the influence of the magnetic field. The idea is that the balls should be captured in the magnetized area for each rotation of the drum. In the practical operation of these machines, however, it has been found necessary in the Soviet Union to arrange a separate lifting device for raising the steel balls to an upper area, where they are brought into contact via a trough with a magnetized area on the rotating drum.

The object of the present invention is therefore to provide an improved design of a wet magnetic separator, whereby the above-mentioned difficulties can be avoided.

According to the invention, the rotor of such a wet magnetic separator is mounted on a horizontal shaft instead of on a shaft vertically oriented in a conventional manner. The rotor has an annular separator portion formed by a pair of spaced apart annular sidewalls, and a plurality of radial, non-magnetic material partitions extend between these sidewalls so as to form a series of separate compartments which are magnetically insulated. apart with open inner and outer ends. Induced magnetic pole pieces are placed in each compartment in such a way that particulate matter can pass through resp. compartment. At least one magnet is located in the immediate vicinity of one of the annular side walls, and preferably a magnet is arranged adjacent to each side wall. They may be located at either an upper or a lower region of the rotor to generate a magnetic field in each compartment as it passes the magnet.

Inlet means are arranged to inwardly feed a slurry into each compartment through an open end thereof, then resp. compartments are located within the magnetic field of the magnet. The feed inlet should be located at the leading edge of the magnetic field, with the magnetic particles immediately adhering to the surfaces of the induced pole pieces, while non-magnetic particles pass through the compartment. Gatherings are located below the compartments in this area for collecting the non-magnetic particles passing therethrough.

Inlet means are also arranged to supply downwards a first flushing liquid to an upwardly facing compartment opening before the compartment leaves the above-mentioned magnetic field. These means preferably consist of a water coil device operating at low pressure and serve to remove non-magnetic material, which is held by the adhered magnetic particles. 10 15 20 25 30 35 40 7712967- 4 Collection gutters are also located under the compartments in these areas to collect an intermediate product separately. This intermediate may contain a certain amount of magnetic particles, which may be returned to the slurry to be fed.

Additional inlet means are provided at a location located about 1800 degrees from the magnet and where the magnetic field has substantially no field strength, for supplying a second flushing fluid to an upper, open end of the compartment. These inlet means are preferably designed as a spray nozzle for spraying water or a water-air mixture under high pressure, so that magnetic particles are removed from the surfaces of the induced pole pieces. Gutters are also placed under the compartments in these areas for separate collection of the magnetic products.

In order to be able to arrange the gutters, etc. in the vicinity of the inner ends of the compartments, the annular separator portion is connected to the rotor hub by means of an axially displaced web portion. The hub may, for example, be connected to one side wall of the annular separator portion by means of a disc-like web or radial spokes.

Since the magnets are in the vicinity of the flat annular end portions of the rotor, the magnetic pole pieces may have flat surfaces in the vicinity of the rotor. The magnets can be placed on one or both sides of the rotor and can be mounted either at an upper or at a lower area.

Preferably, the magnets are mounted in pairs with opposite poles on either side of the rotor and with the opposite poles connected by an annular yoke of mild carbon steel to form a closed magnetic circuit. The magnets can consist of either electromagnets or permanent magnets, whereby the use of permanent magnets in this apparatus for + is considerably simplified thanks to the end surfaces of the flat poles. A particularly advantageous permanent magnet for this purpose consists of a ceramic permanent magnet, for example made of barium ferrite. According to a preferred embodiment, a ceramic permanent magnet can be used, which has north and south polarity on the same side.

For effective operation, the non-magnetic partitions should be relatively thick, preferably at least 2.5 cm or several times thicker.

This ensures a sufficient separation of the magnetic effect in the different compartments, so that each compartment can function substantially independently of adjacent compartments. The induced pole pieces may be made of magnetic permeable steel, e.g. mild carbon steel, stainless steel ("4OO series¶, low carbon steel, etc. and have the shape of knurled plates, wedge wire, screw- i 10 l5 20 25 30 35 40 ..........._.- In particular, when using a permanent magnet with north and south polarity reaching the same side, knurled plates are particularly advantageous as induced pole pieces, .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ... They also allow an unobstructed flow of the solids and a simpler cleaning of the magnets with pressurized water.The induced pole pieces preferably have a number of sharp edges, corners or surfaces, which cause convergence of the power lines in the effective magnetic field in which the pole pieces are placed.

When individual objects, such as steel balls, are used as induced pole pieces, these are held in position in the separator compartments by inner and outer screens, through which the article material can pass. By ensuring a certain free space in each compartment, the balls will move during the rotation of the rotor, whereby they are kept clean and do not stick to each other.

This in turn prevents the passages from being clogged by the material moving through the compartments, and enables substantially extended operating time without interruption.

As mentioned above, the magnets can be placed near either an upper or a lower portion of the ring. When the magnets are located at the upper portion of the ring, the slurry is fed through the upper, outer, arcuate region of the ring, the non-magnetic material being discharged through an inner, arcuate region, while the magnetic material is attracted to the induced pole pieces in the separator compartment. When the compartment reaches the lower position outside the magnetic field, the magnetic particles are flushed away by a water or air-water jet coming from an inner, arcuate area. The flushing out of magnetic particles thus always takes place upstream in relation to the feed flow. The high-magnet material, which can accumulate on top of the induced pole pieces during the introduction of the slurry, will be at the bottom after the rotation of the ring 1800, so this accumulated material is washed away first. Consequently, the risk of the separator being clogged by high-magnetic particles is further reduced. coarser material, which is too large to pass through the gaps between the induced pole pieces, at the same time as the magnetic fraction.

The machine is suitable for separating a number of different materials, and it can be used, for example, for the production of a magnetic concentrate when the magnetic material is the desired product, for example a concentrate of ores, such as hematite or chromite, with relatively low magnetic susceptibility. Alternatively, it can be used in collecting and removing magnetic impurities from non-magnetic materials, e.g. removal of magnetic contaminants, such as brolite, garnet or iron oxides, from ceramics, chemicals, oils and steel waste. It is particularly advantageous in separating weak magnetic contaminants from industrial waste. For this purpose, a permanent magnet is particularly suitable, as it provides extremely low operating costs. In addition, larger contaminant particles in such industrial waste will not interfere with the operation of the machine, since they are always removed by the countercurrent separation of the magnetic particles.

The invention is described in more detail below with reference to the accompanying drawings, in which Fig. 12 Fig. 3 shows the separator in side view and partly in section; Fig. Shows the separator end view; shows a vertical section through the round ring; an alternative embodiment of the separator in side view Fig. 4 shows and partly in section; Fig. 5 shows a section along the line V-V in Fig. 4; Fig. 6 shows in plan view some details of an alternative embodiment; Fig. 7 shows a section through the embodiment according to Fig. 6; Fig. 8 corresponds to Fig. 6 and schematically illustrates the lines of force of the magnetic field; Fig. 9 shows a vertical section through a further embodiment of the separator; and Fig. 10 shows the embodiment according to Fig. 9 in side view and partly in section.

As shown in Figs. 2 and 3, this apparatus has a rotor 10 rotatably mounted on a horizontal axis 11. The rotor comprises two spaced apart annular plates 12 of mild carbon steel between which are inserted a number of radial, truncated, wedge-shaped partitions 13 of non-magnetic material, so that a number of magnetically insulated separator compartments "C" are formed. These partitions can, for example, be made of stainless steel, aluminum, copper, etc. The compartments pair open outer and inner ends 32 resp. 31. At an inward distance from the outer ends 32, screen net portions 15 are arranged, and at an outward distance from the inner ends 31, screen net portions 14 are arranged. These screens 14 and 15 retain a plurality of steel balls 16 between them. These steel balls can advantageously be ordinary ball bearings with a diameter between 0.6 and 2.5 cm. They form a magnetic collection zone and form induced pole pieces under the action of a magnetic field. As shown in Fig. 3, the compartments "C" are not completely filled by the balls 16. Thus, at the position for feeding the slurry 16, the balls 16 rest on an outer screen 15 with a space adjacent the inner screen 14.

At the position of the discharge of the magnetic particles, the balls 16 have been moved within the compartment so that they rest on the inner screen 14 with a free space next to the outer screen 15. This is an important feature when using balls as induced pole pieces. The spheres create a tortuous path for the flowing slurry and thereby provide a highly efficient collection of magnetic particles.

If the beads are left in this position during all steps of the process, they are quickly bonded together by materials from the slurry that have penetrated into the small spaces between the beads. In the apparatus according to the invention, however, the balls are in considerable movement during each rotor revolution, and this prevents the accumulation of material in the spaces between adjacent balls. This improves the separation efficiency from the outset, and this high separation efficiency can be maintained for long operating periods.

Additional partitions, namely an outer partition 18 and an inner partition 19, are arranged radially on each side of resp. partition wall 13. These partitions 18,19 may consist of simple radial plates, as shown in Fig. 1, or have a triangular cross-section which contributes to an even supply of slurry and flushing water to the compartments.

The annular separator ring section of the rotor is attached to a hub portion 20 and is displaced in such a way that a free space arises near the inner ends 31 of the compartments 31. The hub 20 is mounted on a rotatable shaft 11, which in turn is supported in a bearing bracket 21. The shaft can be driven by an electric motor (not shown) by means of a sprocket 22.

A permanent magnet device 23 is mounted next to a lower part of the rotor 10 with a north pole permanent block 24 on one side and a permanent magnet block 25 on the other side. The polytes are so small spaces are formed between the polytes and the surfaces of the rotor. of mild carbon steel, the poles 24 and 25, forming a south pole position, connect a yoke 26 to free space 27 between the yoke and the sides of the poles. The yoke serves as the magnetic circuit and thereby amplifies the magnetic flux. The yoke has a hole 28 which allows water and non-magnetic and deflection plates 58 are provided between the poles. particles passing through the space 27 for guiding the material coming from the rotor out through the hole 28.

A feed inlet pipe 29 is connected to a feed head 30 so that the material to be fed enters the compartments C via the inner ends 31 approximately at the lowest rotational position. The fed material should enter the area of the leading edge of the magnet 23, and as the material passes through the compartment C, the magnetic particles adhere to the steel balls 16, while the liquid and the non-magnetic material pass directly through the compartment and out through the outer end 32, where it is collected in a non-magnetic collecting channel 33 and removed via a line 34. A spray water head 35 operating at low pressure is likewise placed in the vicinity of resp. open compartment end 31 in a lower area and is arranged to supply rinsing water for rinsing away non-magnetic material, which is stuck on or between the magnetic particles. The rinsing water should be supplied while it is still under the direct action of the magnets 23, so that the rinsing does not remove any magnetic particles. In this embodiment, the rinsing water is collected by the gutter 33, but it will be appreciated that if a separate collection of an intermediate product is desired, a separate gutter and a special outlet can be provided for this purpose under the spray water head 35.

Next to the rotor and diametrically opposite the magnet 23 there is a device for supplying water or air-water jets under high pressure. The spray nozzles 36 are located at an area with minimal influence from the magnetic field created by the magnets 23, so that the magnetic particles can be easily removed from the beams 16. The spray water and the detached magnetic particles are collected in a chute 56 and removed from the machine via a line 57.

Fig. 4 shows an alternative embodiment of the separator, the magnets 37 being located in the vicinity of the upper region of the rotor, diametrically opposite the position in Fig. 1. These magnets comprise a north-pole permanent magnet block 38 on one side of the ring 10 and a corresponding south pole 39 on its opposite side. The poles are connected to a yoke 40 of mild carbon steel to form a space 41 between the yoke and the sides of the magnets. The feed inlet pipe 42 and the feed head 43 are located at the upper part of the ring 10 at the leading edge of the magnet, the feed head 43 extending through an opening in the yoke and the slurry being fed through the outer open ends 32, while the non-magnetic material and water flow out through the inner , open the ends 31 for collection by the chute 59 and the conduit 60. The rinsing water head 53 is also located at the upper region of the ring 10 within the field of the magnet 23 and extends through the yoke so that the rinsing water enters through the outer end 32 and flows out through the inner end. 31 to be collected by the chute 59. If desired, the chute 59 can be replaced by a pair of chutes located side by side, one chute being below the feed device 43 for collecting non-magnetic particles, while the other is below the rinsing water head 53 for the collection of intermediate products. The nozzles 10 15 20 25 30 35 40 7712967-4 9 46 for supplying water or air-water jets under high pressure are in this exemplary embodiment located in the inner area at the lower part of the ring 10, these jets being injected downwards through the inner ends 31 and flows out together with the magnetic particles through the outer end opening 32 to the chute 44, from where the material is removed via the conduit 45.

With the wide partitions 13 it may also be desirable to arrange wedge-shaped flow deflectors in the vicinity of the ends of the partitions.

They may, for example, comprise an outer wedge-shaped deflector 54 and an inner wedge-shaped deflector 55, as shown in Fig. 4. These are preferably made of the same material as the partitions and have the task of directing the flow to resp. compartment C and reduce splashes and prevent the accumulation of material on the ends of the partitions.

Figs. 6, 7 and 8 show a further arrangement of magnets and induced pole pieces, wherein the magnets can be located at either an upper or a lower region of the ring 10. Again, the magnets are located on opposite sides of the ring 10 and each of these magnets is in the form of a block of oriented barium ferrite. Each block is oriented in such a way that half of the block is a south pole 47 and the other half is a north pole 48. A permeable plate 49 of steel is attached to each magnetic block so that the magnetic circuit closes, and this arrangement gives those in fig. 8 schematically show the magnetic flow lines.

A magnetic arrangement of this type can give a magnetic field strength of about 8000 Gauss in the area between the induced pole pieces.

In this magnetic arrangement, in order to prevent knurled short circuit of the magnetic flux, it has been found advantageous to use plates 51 as induced pole pieces. Knurled plates are in and 3,830,367.

The plates are arranged in compartments separated by non-magnetic intermediate wells and are described in more detail in the US patent walls 50. The material to be separated flows down into the space 52 between the plates 51, the magnetic particles collecting on the grooved surfaces of the plates. It will be appreciated that all other parts of the separator, incl. the feed and coil devices as well as the output devices, may be the same as those described in connection with Figs. 1-5.

In the special permanent magnet configuration according to Fig. 6, the magnetic particles during the feed through the feed head will be under the influence of the south pole and orient themselves on the grooved plates under this south pole influence. As the tray moves to the area of the North Pole, the magnetic particles will reorient under the influence of the new magnetic field, so that non-magnetic particles can easily ___. , __..__.._.-._ ..._ ..-_ _..

Figs. 9 and 10 show another embodiment with the magnets adjacent to the upper part of the rotor. The rotor rotatably mounted on a horizontal shaft 61 comprises a mild carbon steel disc member 62 which is attached to the end of the shaft 61 and a ring 65 which is spaced from the outer portion of the disc member 62 to form an annular separator space. 64 in between. This space is limited by outwardly directed, funnel-like, annular portions 66, which form a widened inlet 67.

The space is divided into a number of separate compartments by means of radial partitions 71. Each compartment contains steel balls 68, which are retained in resp. compartments by means of screens 69,70 arranged at the outer and inner ends. A pair of magnets 63 are mounted on either side of the separator compartments and, as shown in Fig. 10, are inclined downward in the direction of rotation relative to the vertical center line of the rotor. The area under the magnets is enclosed by a housing 72 with an outlet 73 at the bottom thereof. Immediately above the magnets 63 is arranged a feed cover 74 with a feed inlet pipe 75 arranged therein.

Below the inlet 75, a collector 76 is arranged to receive the non-magnetic material which is not adhered to the balls 68 in the device formed by the magnets 63 for spraying water downwards through the separator compartments (from the inner field. Spray nozzles 77 for high pressure jets are to the outer end ) when these are at a distance from the magnetic field.

By means of these jets, the magnetic particles are removed from the steel balls 68 and transported out through the discharge hole 73. Additional spray nozzles can also be arranged in the area of the magnets.

Although the above detailed description relates exclusively to embodiments with permanent magnets, those skilled in the art will appreciate that these permanent magnets can be replaced by electromagnets of known type, e.g. those described in U.S. Pat. No. 3,830,367. The invention is further illustrated by the following examples: Example 1 A separator made according to Figs. 9 and 10 was tested, the feed material being uranium ore containing branerite and uraninite as the main uranium components. The ore was ground to a fineness of less than 150 mesh (according to US sieve standard), with 90.4% üDderSte9 325 mesh- It contained o, os1% U3o8. A slurry of this ground ore containing 25% solids was fed to the separator. The ore was separated into 1.3.7% magnetic particles and 86.3% non-magnetic particles. The magnetic current contained 0.493% U3O8 or 83.4% of the amount of U3O8 contained in the feed material. The non-magnetic current contained 0.0656% of U 3 O 3 or 16.6% of said amount of U 3 O 8.

Example gel 2 The same separator as in Example 1 was used for the separation of ferrous minerals from bauxite. The treated ore contained over 60% -10 microns of solid particles with an iron content of 9.4% (Fe2O3). The main pollutants were iron spar, ferrotitanium oxides, iron oxides, biotite, muscovite, garnet, etc.

This ore was fed to the separator as a slurry containing 20% solids. The ore was separated into 14.0% magnetic particles and 86.0% non-magnetic particles, the magnetic stream containing 48.2% Fe 2 O 3 or 7.1% of the original amount of Fe 2 O 3.

The non-magnetic current contained only 3.1% of Fe2O3 or 28.2% of the amount of Fe2O3.

Claims (10)

Magnetic separator for separating solid magnetic particles from a slurry, comprising a rotor (10) rotatably mounted on a horizontal axis (ll) with an annular separator portion formed by a pair of mutual separate annular side walls (12), the separator portion having open inner and outer ends (31 and 32, respectively); induced pole pieces placed in said separator portion in such a way that the particulate material can pass radially therethrough; at least one magnet (23) located in close proximity to an upper or lower region of one of said annular side walls (12) substantially on its vertical diameter for generating a magnetic field in the part of the separator portion passing the magnet; feeding means (30) for feeding the slurry radially downwards to said separator portion through one of said open ends when the separator portion is in the magnetic field of said magnet (23); first supply means (35) for supplying a first flushing liquid radially to said separator portion adjacent to said feed means (30) within said magnetic field of said magnet (23); second supply means (36) for supplying a second flushing liquid radially to said separator portion outside the magnetic field; 3 'a first collecting device (33) for particulate non-magnetic material located below said separator portion in the area of the magnetic field and a second collecting device (56) for particulate magnetic material located below the separating portion at a location located below said second supply means (36); characterized in that a series of radial partitions (13) of non-magnetic material extend between the annular side walls (12) of the rotor (10) for dividing the separator portion into a series of magnetically insulated, radial separator compartments with open interiors (31) and outer (32) ends; - said pole pieces are constituted by magnetically permeable steel balls (16) or knurled plates (51), which are retained in said separator compartment, and - said first supply means (35) are arranged to supply said first flushing liquid radially downwards to the separator compartment. said second supply means (36) are arranged to supply said second flushing liquid downwards to the separator compartments at a location located about 1800 from the magnet (23), so that said second flushing liquid passes through the separator compartments in a direction opposite to the slurry input in the separator compartments. Separator according to claim 1, characterized in that said compartment partitions (13) are wedge-shaped and form substantially rectangular separator compartments therebetween. Separator according to claim 1, characterized in that two collecting means (33) are arranged below the separator compartments present in the magnetic field, one collecting means being located below said input means (30) for collecting non-magnetic material, while the other is located under said first flushing liquid supply means (35) for collecting an intermediate product. Separator according to one of Claims 1 to 3, characterized in that the induced pole pieces consist of magnetically permeable steel balls (16), which are enclosed in resp. compartments of inner and outer retaining screens (l4, l5). Separator according to one of Claims 1 to 3, characterized in that a pair of electromagnets are placed on opposite sides of the annular separator portion. 1712957-4 1H Separator according to claim 1, characterized in that a pair of permanent magnets (24,25) are placed on opposite sides of the annular separator portion. Separator according to claim 6, characterized in that the magnets (24; 25) are connected to a magnetically permeable, steel locomotive (26), A separator according to claim 6, characterized in that each magnet is permanently oriented, one half being a south pole (47) and the other half being a north pole (48). Separator according to one of Claims 1 to 3, characterized in that the magnets (37) are located in the immediate vicinity of an upper region of the rotor (10) on its vertical axis. Separator according to one of Claims 1 to 3, characterized in that the magnets (23) are located in the immediate vicinity of a lower region of the rotor (10) on its vertical axis.