BÄCKLUND, Erik (PI 280, Skellefteå, S-931 99, SE)
Claims
1. A method to separate different materials from each other, such as, for example, elements and/or their compounds, characterised in that the material is pre-treated in a cyclone device (10) that comprises a restricted outlet (21) for a gaseous medium and an outlet (14) for material treated in the cyclone, whereby the cyclone device breaks the material down into smaller fractions and changes the electrostatic charges of the materials, and in that the different materials are subsequently separated from each other by means of electrostatic separation.
2. The method according to claim 1, characterised in that the electrostatic separation takes place in direct association with the output flow of material from the cyclone.
3. An arrangement to separate different materials in a mixture of materials from each other, whereby the mixture of materials (A-C) comprises at least two different materials, characterised in that the arrangement comprises a cyclone device (10) with a restricted outlet (21) for gaseous medium and an outlet (14) for material treated in the cyclone device, and in that the arrangement comprises an arrangement (70) for electrostatic separation.
4. The arrangement according to claim 3, characterised in that the arrangement (70) for electrostatic separation comprises at least two electrodes (E1,E2) that have different electrical charge. 5. The arrangement according to claim 4, characterised in that the electrodes (E1,E2) have the form of plates and diverge from each other when considered in the direction of flow of the material.
6. The arrangement according to any one of claims 3-5, characterised in that the arrangement comprises a collection arrangement (80). 7. The use of a method according to either claim 1 or 2 to separate different materials in a mixture from each other.
8. The use of an arrangement according to any one of claims 3-6 to separate different materials in a mixture from each other. |
A method for separating elements and/or their compounds from each other
The present invention relates to a method for separating elements and/or their compounds from each other.
Background to the Invention
There is a great need in a number of different contexts of separating different materials from each other. The recovery of metals from dressed ore and the recycling of materials at recycling plants can be mentioned as examples of such contexts. There are innumerable other areas in which a simple and cheap method for separating different minerals or materials from each other is required.
Object of the Invention
It is an aim of the invention to demonstrate a method for separating different elements or their compounds from each other. The elements or their compounds are, according to the invention, pre-treated in a cyclone that includes a vortex collector with an outlet that is restricted, and the different elements or their compounds are subsequently separated from each other by means of electrostatic separation.
Brief description of the drawings
Figure 1 is a longitudinal section through a cyclone that can be used for carrying out the method according to the invention. Figure 2 is an enlargement of a detail shown in Figure 1. Figure 3 is a schematic illustration of the invention.
Detailed description of the device displayed and of methods as examples of the invention
Figure 1 shows a cyclone that can be used for the method according to the invention. It has a body with a cylindrical part 11 with a tangential inlet from an inlet line 12. The cylindrical part is contiguous with a conical part 13 with a bottom outlet 14. A vortex collector in the form of a cylindrical pipe 15 that may have a conical end 16 extends downwards through the cover 17 of the cylindrical part and acts as an air outlet to the atmosphere. The axial position of the vortex collector can be adjusted as has been indicated in the drawing by the lifting jacks 18,19. A restriction for the outlet is formed by a cone 20
such that a ring-shaped exit slit 21 is formed, and such that this slit can be adjusted by changing the axial position of the cone 20 relative to the pipe 15 with the screw 22.
When air or another gas is blown into the inlet line 12 by a fan, not shown in the drawing, a downwardly moving vortex is formed that subsequently turns and forms a central upwardly moving vortex that is collected by the vortex collector 15. The dashed-dotted lines 30 show the boundary between excess pressure on its outer surface and negative pressure on its inner surface.
The bottom outlet 14 is shown in more detail as Figure 2, and it is there made clear that the material 31 that is added to the inlet air in the inlet line 12 is deposited onto the conical wall and is transported downwards and out of the outlet. The drawing of the dashed-dotted lines 30, which are also present in Figure 1, makes it clear that there is excess pressure along the wall while there is negative pressure in the centre of the outlet, such that air flows inwards, as is shown by the arrow 32, which is why it is an alternative that material can be introduced there instead of in the inlet air line 12. The outlet 14 can be modified such that it becomes ring-shaped. The cyclone and its properties are not described in more detail here, since a cyclone of this type is described in more detail in US 5,236,132; US 5,598,979; and US 6,517,015 B2. Reference is made to these documents.
It is general for the invention that a mixture of materials A,B,C is added to a cyclone 10 in accordance with that which has already been described, whereby the cyclone arrangement breaks the mixture of materials into smaller fractions, dries the mixture of materials and changes (increases) the electrostatic charge of the materials. The milled mixture of materials A-C that is discharged from the cyclone arrangement is treated further by means of electrostatic separation in which at least two electrodes E1,E2 with different electrical potentials are used. Electrodes with flat shapes, for example, may be used, with a supply voltage that can be varied such that the equipment can be adjusted for different operating conditions.
The case that has just been described is shown schematically in Figure 3 where a mixture of materials A-C is added to a cyclone device 10. When the mixture of materials A-C leaves the cyclone device 10 it has been further crushed and dried, while at the same time the electrostatic charges of the material A-C has been changed through the charges being
increased to different degrees. The mixture of materials A-C that has been treated by the cyclone device 10 has been denoted in Figure 3 with the reference number 50. An intermediate step that may be used has been denoted with the reference number 60. An arrangement 70 for electrostatic separation, which comprises electrodes E1,E2, is subsequently used to separate the materials A-C into three different piles 81-83, as is illustrated in Figure 3. The detailed design and construction of the arrangement can naturally be varied in many different ways within the scope of the innovative concept.
The electrostatic separation arrangement 70 shown in Figure 3 comprises two electrodes El and E2 that have flat shapes. The electrode El constitutes in the example shown a negative pole, and the electrode E2 a positive pole. The difference in potential between the electrodes is naturally adapted to the different materials that are to be separated and their electrostatic charges. The electrodes El and E2 shown diverge from each other when considered in the direction of fall of the materials. This is to ensure that the desired fall pattern of the particles in the materials is achieved when separating the materials, as is indicated in the drawing.
Positively charged material particles that are emitted from the cyclone arrangement 10 thus arrive in the pile of material 81 , negatively charged material particles that are emitted from the cyclone device 10 arrive in the pile of material 83, and uncharged or weakly charged material particles arrive in the pile of material 82 of a collection arrangement 80. The fall pattern of the particles is indicated schematically with dashed lines in Figure 3.
It should be realised that the electrostatic separation arrangement can be constructed in many different ways within the scope of the present innovative concept.
Example
Wet dressed ore is added to the cyclone device 10. The mixture of materials can be finely crushed and dewatered in the same operation by means of the cyclone device 10 and the finely crushed material can achieve, for example, a particle size of approximately
0.05 - 0.15 mm. The material content of the dressed ore is crushed and dried during its treatment in the cyclone device and the materials that leaves the cyclone device is triboelectrically charged, whereby the desired properties can be finely adjusted through regulation of the operating parameters of the cyclone device.
The triboelectrical charge arises as a result of friction between the crushed and dried particles of material in the cyclone arrangement. Certain particles acquire a positive charge while other particles acquire a negative charge due to the electron transfer that occurs between different materials. Triboelectricity arises during static contact between materials with different dielectric constants (permittivities) when an electron transfer occurs between the materials. Electrons thus pass from the material that has the higher permittivity to the material with lower permittivity. The transfer of electrons continues until the polarity of the two surfaces is the same. If the two materials subsequently are suddenly separated, and the electrons do not have any opportunity to compensate, a positive charge will remain on the material that has donated electrons while at the same time a negative charge will remain on the material that has accepted electrons.
The dried, crushed and electrostatically charged particles of material that leave the cyclone device 10 through its bottom outlet 14 are subsequently separated from each other by means of electrostatic separation in the manner described above.
It is advantageous to carry out the electrostatic separation directly after the particles of material have left the cyclone since the electrostatic charge of the particles of material decreases successively with time. The detailed design and operating parameters of the electrostatic separation arrangement must, of course, be adapted to the current operating conditions.
It should be realised that not only dry but also wet mixtures of material can be separated with the method according to the invention. The invention can be applied in innumerable other areas.
The possibility of combining the present method with magnetic separation is available.
Electrostatic separation of mixtures of material that previously were very difficult to separate electrostatically is made possible by the method according to the invention. The crushing effect of the cyclone device and its ability to change charge can be regulated by, among other factors, the degree of closure of the outlet 21. The cyclone device is adjusted such that the degree of fineness of the crushing and the degree of charging or the change in
the electrostatic properties of the material are adapted to the subsequent requirements for electrostatic separation.
Thus the invention is not limited to that which has been revealed and described. Changes and modifications of this are conceivable within the scope of the attached claims.