Method for continuous magnetic separation of weakly magnetic materials and device for its implementation

Method for continuous magnetic separation of weakly magnetic materials and device for its implementation

The invention relates to the field of magnetic separation of weakly magnetic materials by magnetic properties, in particular, in mining, chemical and other industries.

A known method of continuous magnetic separation of weakly magnetic materials, which includes feeding the enriched material into the gap between elongated ferromagnetic bodies, the vertical plane of symmetry of which is perpendicular to the magnetic field, and the side surfaces of the ferromagnetic bodies turned to the gap have a curved profile in cross section; moving the material towards the place of removal of non-magnetic particles from the gap into the non-magnetic separation product; removing magnetic particles from the stream of enriched material and moving to the place of their removal from the gap into the magnetic separation product; removal of non-magnetic particles remaining in the stream of enriched material into a non-magnetic separation product.

The disadvantage of this method is the movement of the enriched material from the place of its supply into the gap between the ferromagnetic bodies in the direction to the place of removal of non-magnetic particles from the gap into the non-magnetic separation product. As a result, in order to remove magnetic particles from the stream of enriched material, and then divert them to sufficient removal to prevent mutual contamination of magnetic and non-magnetic separation products, it is necessary to create a field of magnetic forces of appropriate length perpendicular to the direction of movement of the material, which requires large energy expenditures.

This method is implemented in a device that consists of

     

  • of a magnetic system with inclined tips, the surfaces of which are turned to the interpolar gap, have a curved profile in cross section;
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  • a tilt camera installed between them;
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  • devices for feeding into the chamber the material intended for enrichment;
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  • devices for removing magnetic and non-magnetic separation products;
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  • moreover, the walls of the chamber, which are parallel to the magnetic field, are at the same time parallel to the direction from the device for feeding the enriched material to the device for removing the non-magnetic separation product.

The principle of operation of the device is as follows.
The material intended for enrichment enters the inclined chamber and moves down along its lower longitudinal wall to the device for removing the non-magnetic separation product. Due to the given orientation of the magnetic field and the curved surface of the pole pieces, magnetic forces are generated in the chamber directed perpendicularly upward from the material’s trajectory. Under the action of this force, magnetic particles exit upward from the material flow and move to the device to remove the magnetic separation product. Non-magnetic particles that remain in the material stream enter the device for removing the non-magnetic product.

The disadvantage of this device is the placement of the above chamber walls parallel to the direction from the device for feeding intended for the enrichment of the material to the device for separating a non-magnetic separation product. This placement of the walls of the chamber requires additional energy to direct the magnetic particles to the device for isolating the magnetic product.

The prototype of the proposed method includes

     

  • feeding the material intended for enrichment into the gaps between the elongated ferromagnetic bodies, the longitudinal inclined edges of which have a curved profile in cross section, and the general plane tangent to these edges is oriented at right angles to the direction of the magnetic field;
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  • removal of magnetic particles from a stream intended to enrich the material into a magnetic separation product;
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  • removal of non-magnetic particles through the gaps between the ferromagnetic bodies into the non-magnetic separation product, and the supply and further
    the material intended for enrichment is moved at an acute angle to the common tangent to the longitudinal inclined edges
    ferromagnetic bodies of the plane towards the place of removal of non-magnetic particles into a non-magnetic separation product.

During wet enrichment, water is supplied in contact with the pulp stream intended for enrichment of the material and on one side of the tangent plane common to the ferromagnetic bodies in the direction to the place where the magnetic particles are removed into the magnetic separation product.
The disadvantage of the prototype of the proposed method is to move the stream intended for enrichment of the material at an acute angle to the plane common to ferromagnetic bodies, located tangentially to their longitudinal inclined edges, towards the place of removal of the non-magnetic separation product. Such a movement necessitates the removal of magnetic particles from the stream of enriched material and the direction of the trajectory of their movement to the place of removal of the magnetic separation product. Carrying out a turn in the trajectory of motion requires energy to overcome the inertia forces of the magnetic particles and, in the case of wet enrichment, the pressure head of the pulp, which tend to push the magnetic particles into the gaps between the ferromagnetic bodies, from where they will necessarily enter the non-magnetic separation product.

The prototype of the claimed device consists of a magnetic system, between the pole tips of which are installed elongated ferromagnetic bodies separated by gaps, the upper longitudinal inclined edges of which have a curved profile in cross section, and the general plane tangent to these edges is oriented
at right angles to the direction of the magnetic field; devices for feeding material intended for enrichment, which is placed above the common tangent to the longitudinal inclined edges of the ferromagnetic plates by a plane; walls and partitions designed to specify the inclination of the trajectory of the enriched material relative to this common tangent plane; devices for removing non-magnetic and magnetic separation products, moreover, the surfaces of the walls and partitions that specify the inclination of the trajectory of the enriched material are placed at an acute angle to the common tangent plane of the ferromagnetic bodies.

In the case of wet enrichment, the prototype is equipped with a device for supplying water, which is placed on the same side with respect to the tangent plane common to the ferromagnetic bodies as the device for supplying the enriched material.
The principle of operation of the prototype is as follows. The enriched material is fed into the gaps between the elongated ferromagnetic bodies located in the magnetic field. For a given orientation of the ferromagnetic bodies relative to the magnetic field at and above their rounded edges, a magnetic force directed from the gaps is created.
This force keeps the magnetic particles from moving down through the gaps under the action of inertia and gravity, and during wet enrichment, also the velocity pressure of the pulp, and they move above the gaps above the longitudinal inclined edges of the ferromagnetic bodies to the device for removing the magnetic product. Non-magnetic particles not experiencing
supporting action of magnetic forces, move down through the gaps between the ferromagnetic bodies and enter the device to remove the non-magnetic separation product.
The disadvantage of the prototype of the claimed device is the placement of the surfaces of the walls and partitions, which specify the inclination of the trajectory of the enriched material, at an acute angle to the common tangent plane of the ferromagnetic bodies. With this arrangement of walls and partitions, the material supplied to the enrichment, and with it the magnetic particles, are sent through the gaps between the ferromagnetic bodies into the non-magnetic separation product. The consequence of this is the need for additional energy expenditure to rotate the trajectory of the movement of magnetic particles in the direction to the place of removal of the magnetic product.

The basis of the invention is the task to improve the method of continuous magnetic separation of weakly magnetic materials and the device for implementing this method by creating conditions for eliminating the energy costs of overcoming the inertia forces and high-speed pressure of the pulp, which tend to push the magnetic particles into the gap
between ferromagnetic bodies. This would reduce energy costs without reducing the extraction of magnetic particles into the magnetic separation product.

The solution to this problem is achieved by the fact that in the method of continuous magnetic separation of weakly magnetic materials, which includes

     

  • the supply of enriched material to the gaps between the elongated ferromagnetic bodies, the longitudinal inclined edges of which have a curved profile in cross section, and the general plane tangent to these edges is oriented at right angles to the direction of the magnetic field; removal of non-magnetic particles down through the gaps between the ferromagnetic bodies into a non-magnetic separation product;
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  • the removal of magnetic particles into the magnetic separation product, according to the invention, the supply and further movement of the material intended for enrichment is carried out towards the place of extraction of magnetic particles into the magnetic separation product parallel to the longitudinal inclined edges of the elongated ferromagnetic bodies at an angle of 30 * to the vertical.

During wet enrichment, water is supplied into the gap between the ferromagnetic bodies in the gap between the ferromagnetic bodies in contact with the pulp stream of the material intended for enrichment, but on the opposite side, with respect to the tangent plane common to the ferromagnetic bodies, in the direction to the place where the non-magnetic particles are removed into the non-magnetic separation product.

The solution of this problem is also achieved by the fact that in the device for implementing the method of continuous magnetic separation of weakly magnetic materials, which consists of

  • magnetic system with pole pieces;
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  • installed between them at least two elongated parallel inclined ferromagnetic bodies placed relative to each other with gaps, the longitudinal inclined edges of which have a curved profile in the cross section and a common plane that touches them, oriented at right angles to the direction of the magnetic field;
     

  • devices for feeding material intended for enrichment, which is placed above a common tangent to the longitudinal inclined edges of the ferromagnetic
    plates by plane;
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  • walls and partitions designed to specify the inclination of the path of movement of the enriched material relative to this common tangent plane;
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  • devices for removing non-magnetic and magnetic separation products, according to the invention, the surface of the walls and partitions that define the inclination of the trajectory of the enriched material, are placed parallel to the common tangent to the ferromagnetic bodies of the plane at an angle of 30? 100 to the vertical.

In the case of wet enrichment, the device is equipped with a device for supplying water, which is placed under a common plane tangent to the ferromagnetic bodies.
Along the lateral surfaces of the ferromagnetic plates along the entire height of the separation channel, adjacent adjacent plates of non-magnetic material are installed.
The causal relationship between the features of the invention and the achieved result (creating conditions that can reduce the magnetic field induction without reducing the extraction of magnetic particles into the magnetic separation product) is as follows. When feeding and moving the enriched material parallel to the longitudinal inclined edges of ferromagnetic bodies with a curved profile in cross section, the particle inertia does not have a component that acts against the magnetic force directed from the gap and forces magnetic particles to enter the gaps between the ferromagnetic bodies, after which they can move on into the non-magnetic separation product. The same applies to the velocity pressure of the pulp on the particles during the wet separation process. In this case, there is a need to move water through gaps below the edges of ferromagnetic bodies, above which the pulp moves. Without this water, the pulp flow would necessarily expand, creating precisely those components of the velocity head that would force the magnetic particles to overcome the magnetic forces and enter the gaps between the ferromagnetic bodies.

Thus, when the enriched material is fed parallel to the longitudinal inclined edges of the ferromagnetic bodies, but above the tangent plane common to them, and in the case of wet enrichment, even when the water is supplied to the gaps between the ferromagnetic bodies below this plane, there are no inertia forces and velocity pulp pressure, which would be sent to the gaps. Due to this, only the downward gravity forces the magnetic particles to move towards the gaps between the ferromagnetic bodies. In comparison with the prototype, this makes it possible to reduce the induction of the magnetic field without reducing the extraction of magnetic particles into the magnetic product, or with the same induction of the magnetic field to achieve greater extraction of magnetic particles.
It was established experimentally that the rational angle of inclination of the longitudinal inclined edges of the ferromagnetic bodies to the vertical is 30 *. At a smaller angle, non-magnetic particles do not have time to leave the flux of magnetic particles and enter the magnetic product, polluting it. At a larger angle of inclination, the speed of movement of the material through the gaps between the ferromagnetic bodies decreases, as a result of which the enrichment rates deteriorate.
The orientation of the parallel ferromagnetic bodies relative to the magnetic field is defined by the fact that the common plane, which touches the longitudinal inclined edges of the ferromagnetic bodies, is placed at right angles to the magnetic field. With this orientation, the magnetic force is directed from the gaps between the ferromagnetic bodies. The physics of this phenomenon is described in detail in the literature? 2, 4 ?.

Due to the fact that the longitudinal inclined edges have a curvilinear profile in their cross section, for example, rounded, ellipsoidal, and so on, the gaps do not create magnetic forces directed towards the ferromagnetic bodies, which would be sufficient to attract and retain magnetic particles on the walls of the gaps? 4 ?
To implement the method, a laboratory separator was developed and manufactured. It consists of a magnetic system and a separation channel located between its pole tips. The latter has two longitudinal inclined ferromagnetic plates placed in vertical planes with a thickness of 10 mm and a length of 200 mm. The planes of the ferromagnetic plates are oriented perpendicular to the surfaces of the pole pieces of the magnetic system. The plates are installed with a gap of 10 mm relative to each other. The upper longitudinal edges of the plates are rounded in cross section and have a common plane that touches them, inclined at an angle of 300 to the vertical. The radius of curvature is 5 mm. Non-ferromagnetic material plates are attached to the rounded edges of the ferromagnetic plates, which cover the zone of action of the greatest attractive magnetic forces. Plates forming the bottom and the ceiling of the separation channel are hermetically attached to ferromagnetic and non-ferromagnetic plates. These last two plates are parallel to the plane touching the rounded edges of the ferromagnetic plates.

A device for feeding the pulp of the enriched material is placed above the gap above the longitudinal edges of the inclined ferromagnetic plates rounded in cross section. Its lower and upper walls (bottom and ceiling) are parallel to the common tangent plane to the ferromagnetic bodies. Below these edges is a device for supplying water to the gap between the ferromagnetic plates. Near the lower ends of the inclined ferromagnetic plates are devices for removing a non-magnetic and magnetic separation product. Due to the given orientation of the surfaces of the separation channel and the pulp feeding device, the latter moves along the gap parallel to the longitudinal inclined edges of the ferromagnetic plates and does not create high-pressure forces that would aim to direct the magnetic particles
into the gap between the plates.
Owing to the given orientation of the ferromagnetic plates relative to the magnetic field at the level of their edges rounded in the cross section, magnetic forces directed from the gap arise, which are described in detail in the literature? 2, 4 ?. Non-magnetic particles under the action of gravity freely enter the gap between the plates and move there further to the device for removing the non-magnetic separation product. Magnetic particles are held by magnetic forces from entering the gap between the ferromagnetic plates and move above the gap to the device for removing the magnetic separation product.
Manganese ore with a particle size of 4–0 mm with a manganese content of 21.4% was enriched in a laboratory separator. Concentrated ore pulp was fed into the separation channel at a speed of 0.2 m / s.
Non-magnetic quartz, under the influence of gravity, fell into the gap between the ferromagnetic plates and moved further into the device for removing the non-magnetic separation product. Magnetic manganese, which was supported by magnetic forces, moved over the gap that separates the ferromagnetic plates, above their inclined longitudinal edges to the device for removing the magnetic separation product.
In order to assess the effectiveness of the proposed method and device, the enrichment of the same manganese ore was also carried out on a laboratory separator, which is the prototype of the claimed and was made according to the patent. In accordance with this patent, the pulp was fed into the separator not in parallel, but at an acute angle to the common tangent to the longitudinal inclined edges of the plane’s ferromagnetic bodies. Ferromagnetic bodies are tilted at an angle of 80 to the vertical. Magnetic particles passed into the water, which was supplied from the same side of the mentioned tangent plane as the pulp. The test results are shown in the table.
According to the above data, the inventive separator gave the same enrichment results as its prototype, but with induction one and a half times smaller (0.6 T instead of 0.9 T). This confirms the effectiveness of the new enrichment method and device for its implementation. In the case of enrichment according to the patent when placing inclined longitudinal edges
ferromagnetic bodies at an angle of 300 to the vertical, magnetic particles in the magnetic product were hardly removed.
 


The separator includes a magnetic system 1, in the interpolar gap of which one or more rows of elongated inclined ferromagnetic bodies are installed in the form of plates 2 placed with gaps 3 relative to each other. The planes of the plates are vertical and parallel to the magnetic field. As an example, the figures show one row of plates. The upper longitudinal inclined edges of the 4 plates are rounded in cross section. Non-magnetic plates 5 are adjacent to these edges, which cover the area where the attracting magnetic forces are greatest. The plates and the distance spacers separating them in this case are made as a whole.
The device 6 for feeding the pulp of the enriched material is placed above the longitudinal rounded in longitudinal cross-section of the inclined longitudinal edges of the ferromagnetic bodies. Below these edges there is a device 7 for supplying water to the gaps between the ferromagnetic plates.

The lower and upper surfaces of the pulp feeder and the distance gaskets between the ferromagnetic and non-magnetic plates, defining the inclination of the path of the enriched material, are placed parallel to the common tangent plane to the ferromagnetic bodies at an angle of 30 * to the vertical.
Near the lower ends of the inclined ferromagnetic plates there are devices for removing non-magnetic 8 and magnetic 9 separation products.
Along the lateral surfaces of the ferromagnetic plates along the entire height of the separation channel, adjacent plates 10 of non-magnetic material are installed.
The pulp from the device 6 enters the gaps between the non-magnetic plates 5 above and parallel to the longitudinally rounded cross-sectional edges of the inclined ferromagnetic plates. Below these edges, water is supplied from the device 7 into the gaps between the ferromagnetic plates.
Non-magnetic particles (white) under the influence of gravity fall down and are transported through the gaps between the ferromagnetic plates to the device 8 for removal of the non-magnetic separation product.
The magnetic particles (black) are supported by magnetic force, which is directed from the gaps between the ferromagnetic plates, and is transported along the gap between the non-magnetic plates by pulp, in which the number of non-magnetic particles is gradually reduced, to the device 9 for removing the magnetic product.
Non-magnetic plates 5 may not be used if there are no strict requirements for the purity of the magnetic product. This allows you to increase the extraction of magnetic particles in the magnetic product and simplify the design of the separator. In this case, the role of non-magnetic plates is played by weakly magnetic particles, which are pulled from the curved surface of the longitudinal inclined edges of the ferromagnetic bodies. These particles are attracted from the part of the material that moves over the ferromagnetic plates, not over
the gaps between them.

The causal relationship between the essential features of the device and the achieved result is that the device allows you to implement the essential features of the proposed method of enrichment of weakly magnetic materials.
When wet enrichment, the lower and upper surfaces of the pulp feeder, as well as the lower and upper inner surfaces of the separation channel (in the figures, these are the surfaces of the spacers between the plates facing the inside of the channel) determine the direction of movement of the pulp, and, therefore, enriched
material relative to the common tangent to the plane’s ferromagnetic bodies. Therefore, they are placed parallel to this plane at an angle of 30 * to the vertical.
When dry enrichment is parallel to the common tangent plane to the ferromagnetic bodies, there can be only the lower surface of the power supply device, along which the enriched material slides before entering the separation zone. In this case, only this surface determines the direction of movement of the material. Moving in
the separation zone above the gap between the ferromagnetic plates of the enriched material is not supported by any rigid surface. Non-magnetic particles, after they exit the stream of enriched material down into the gap between the ferromagnetic bodies, become an enrichment product, not an enriched material.
The direction of their movement does not affect the process of separation of the rest of the enriched material. Therefore, the movement of non-magnetic particles after entering the gap between the ferromagnetic bodies can be carried out on the surface with any desired angle of inclination.

Due to the described arrangement of the surfaces of the power supply device and the separation chamber, which determine the direction of movement of the enriched material, the magnetic particles inside the separation chamber move parallel to the longitudinal rounded edges of the ferromagnetic bodies and do not have such a component of their velocity that would be directed into the gaps between the ferromagnetic plates. The absence of such a component of the speed allows, in comparison with the prototype, to reduce the magnetic force necessary to keep the magnetic particles from entering the fumes between the ferromagnetic plates, from where they would inevitably come into a non-magnetic separation product. A decrease in magnetic force leads to a decrease in energy consumption with the same extraction of magnetic particles in the magnetic separation product.
When wet enrichment, according to the method, water must be supplied below the longitudinal inclined edges of the ferromagnetic bodies, which is achieved using the appropriate installation of a device for its supply.
Thanks to the installation of plates of non-magnetic material along the side surfaces of the ferromagnetic plates, their abrasive wear is eliminated, and, consequently, the profile distortion of their rounded surfaces is eliminated. This allows you to save a picture of the magnetic forces acting in the separation space. Non-magnetic plates may
Easily removable for easy replacement.
The width of the gap between the ferromagnetic plates depends on the size and magnetic properties of the particles of the enriched material.
The separator can be mass-produced using standard equipment.

INFORMATION SOURCES:
● Pat. US No. 2056426, priority 05.02.36;
● Pat. Of Ukraine No. 15096 A, priority dated March 29, 93 .;
● Pat. USA No. 5568869 A, priority dated 10.29.96.
● Svoboda J., Magnetic Methodth for the Treatment of Minerals, Elsevier Science Publishers B.Y.,
Amsterdam – Oxford – New York – Tokyo, 1987 – p. 286.
AUTHORS: TURKENICH A. M., TURKENICH R. I.
© 2007 MHT