Patent Application
20140374325
The present invention relates to devices and methods for separating feebly magnetic granular materials, which may be either paramagnetic or diamagnetic in nature, for the purpose of isolating specific material from a heterogeneous batch.
In various applications, it is necessary to isolate a specific granular component from a mixed or impure feedstock based its magnetic properties. The magnetism of minerals ranges from ferromagnetic (e.g., iron) to paramagnetic (e.g., aluminum) to diamagnetic (e.g., graphite). In the production of very high-purity quartz (SiO2) for semi-conductors, for example, it's necessary to separate the diamagnetic SiO2 component from paramagnetic mineral impurities. It has been demonstrated that, for the best separation of paramagnetic and diamagnetic materials, a high intensity magnetic field with high field gradients is required.
U.S. Pat. No. 4,882,043 to Jung (hereinafter referred to as “Jung '043”), which is incorporated herein by reference, teaches a roll-type magnetic separator. As depicted in
The “bucking mode” assembly is illustrated in
In the roll-type separator described in Jung '043, a drive motor rotates the roll, such that the bands of diamagnetic material will spin. off the roll surface along a tangent thereto, while the paramagnetic material will cling to the roll longer (as shown in
Table 1 in the upper right of
The present invention addresses these inefficiencies by replacing the rotating roll 201 with one or more stationary inclined magnetic blocks, By making better use of gravitational forces to separate the heterogeneous materials 204, the present invention eliminates the need to generate centrifugal forces through the rotation of a roll 201. This design thereby enables much greater utilization of the system's magnetic energy, while also saving the energy of the motor drive needed to rotate a roll 201.
In the present invention, the magnet arrangement is in the form of a magnetic block, wherein the magnets are composed of rectangular elements of high strength permanent magnets and soft-magnetic strips rather than disks. The magnetic parts are glued together with a high strength glue.
In order to accommodate production rates, the magnets are packaged in blocks, which may be optimized for any particular product. The blocks are mounted on holders that are inclined to receive the product by gravitational feed under adjustable angles to control residence time. The magnet block is mounted on a holder that may be constructed of a weekly magnetic stainless steel. A plurality of splitters in a horizontal spaced relationship are used to separate the different trajectories of diamagnetic and paramagnetic materials.
The magnet system may be equipped with another permanent magnet at the feeder side that eliminates ferromagnetic particles as they would stick and render useless the magnet blocks. As the granular products slides down the magnetic surfaces fed by gravity, the diamagnetic product is laterally separated from the paramagnetic product and is also pushed into different trajectories so that they can be collected in different compartments.
A further advantage of this arrangement is to be able to reduce the layer thickness of the product feed to approach a monolayer and prevent masking of grains that would result in multiple submissions to the magnets.
The foregoing summarizes the general design features of the present invention. In the following sections, specific embodiments of the present invention will be described in some detail. These specific embodiments are intended to demonstrate the feasibility of implementing the present invention in accordance with the general design features discussed above. Therefore, the detailed descriptions of these embodiments are offered for illustrative and exemplary purposes only, and they are not intended to limit the scope either of the foregoing summary description or of the claims which follow.
As shown in
The magnetic separator 10 further comprises a hinged mounting bracket 17, comprising a horizontal base 18 rotably connected by a hinge mechanism 19 to a ramp holder 20. The ramp 14 is supported by the ramp holder 20 at an adjustable angular inclination 13 with respect to the base 18.
The magnetic separator 10 further comprises a material feeder 21 that distributes the admixture 11 by gravity onto the top of the ramp 14 substantially uniformly across the width of the ramp 14. The admixture 11 separates laterally across the ramp 14 to form bands of paramagnetic material 13, along the spacer strips 16, alternating with bands of diamagnetic material 12, along the magnetic elements 15. The bands of paramagnetic 13 and diamagnetic 12 material slide down the ramp 14 and fall from the bottom of the ramp 14 at different trajectories, such that the trajectory of the diamagnetic material 22 has a greater horizontal component than the trajectory of the paramagnetic material 23.
The magnetic separator 10 further comprises one or more first product receptacles 24, such that each first product receptacle 24 is horizontally and laterally positioned to receive one or more of the falling bands of diamagnetic material 22. The separator 10 also comprises one or more second product receptacles 25, such that each second product receptacle 25 is horizontally and laterally positioned to receive one or more of the falling bands of paramagnetic material 13.
The separator also comprises a magnetic filter 26 in the material feeder 21. The magnetic filter 26 removes ferromagnetic material from the admixture 11 so that no ferromagnetic material reaches the ramp 14.
The apparatus is used for separating a diamagnetic material 12 from a dry admixture 11 by adjusting the angular inclination 13 of the base 18 to accommodate a required feed rate of the admixture 11 and feeding the admixture 11 by gravity at the required feed rate onto the top of the ramp 14 substantially uniformly across the width of the ramp 14, so that the admixture 11 separates laterally across the ramp 14 to form bands of paramagnetic material 13, along the spacer strips 16, alternating with bands of diamagnetic material 12, along the magnetic elements 16. The hands of paramagnetic and diamagnetic material slide down the ramp 14 and fall from the bottom of the ramp 14 at different trajectories, such that the trajectory of the diamagnetic material 22 has a greater horizontal component than the trajectory of the paramagnetic material 23. The falling bands of diamagnetic material 22 are collected in one or more first product receptacles 24, each of which is horizontally and laterally positioned to receive one or more of the falling bands of diamagnetic material 22. The falling bands of paramagnetic material 23 are separately collected in one or more second product receptacles 25, each of which is horizontally and laterally positioned to receive one or more of the falling bands of paramagnetic material 23.
Optionally, multiple separators 10 can be arranged in linear arrays, as depicted in
Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that many additions, modifications and substitutions are possible, without departing from the scope and spirit of the present invention as defined by the accompanying claims.
