The present invention relates to a method for separating different elements and/or their compounds from each other.
Ceramic linings are used in the metallurgical industry in ovens, ladles, converters and other vessels. Ceramics based on, for example, magnesium oxide, aluminium oxide or zirconium oxide may be used. The surface layer is subject to wear and is infiltrated in its cracks and pores by the molten metal and/or the slag. When the bricks are removed, they are normally deposited in storage due to the contamination they have acquired. Magnesium oxide has a value of SEK 4-10/kg and zirconium oxide has a value of SEK 50-100/k, and thus a method for recovering a part of the oxide would be of major economic value. Titanium white is an oxide of titanium that is used as a pigment. The new deposits of ilmenite that are currently being surveyed consist to a major part of eluvial sand that is contaminated with chrome oxide, which must be removed in order to obtain pigment. The removal of chrome oxide is an expensive process, and a simpler and cheaper method would be of major economic value. There are innumerable other areas in which a simple and cheap method for separating different minerals is required. It is known through U.S. Pat. No. 6,517,015 B2 that it is possible to increase the paramagnetic susceptibility of; for example, granite in a cyclone.
It is an aim of the invention to accomplish a method for separating different elements or their compounds from each other. The elements or their compounds are, according to the invention, pretreated 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 magnetic separation.
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
Magnesite bricks removed from a steel oven (an LD converter) were crushed to give a particle size of approximately maximum 35 mm and magnetically separated such that the major part of the metallic iron and a portion of the iron oxide were separated. The pre-crushed material was then added to the air that was blown in through the inlet 12 to a cyclone of the type that has been described. The material was crushed to a particle size of approximately maximum 3 mm in the cyclone, and it exited through the outlet 14. This material was separated by a commercially available strong magnetic separation plant into six different fractions by the use of different field strengths. The fraction that was removed first at the lowest field strength contained a total iron content of 30% in the form of iron and iron oxide, while the last fraction contained a weight percentage of iron oxide of 0.2%. Thus it is possible to separate mineral particles that have different mineral compositions. New magnesite bricks also contain 0.2 weight percentage of iron oxide as a contaminant and for this reason the last fraction can be reused for the manufacture of magnesite bricks. It proved to be the case that the paramagnetic susceptibility of the MgO alone had risen from close to zero to 600×10−6 cmg/s by the treatment in the cyclone, while the paramagnetic susceptibility for the iron oxide had risen from approximately 1,000×10−6 to approximately 10,000×10−6 cmg/s. The difference in paramagnetic susceptibility between the original MgO and the original iron oxide is too small to be able to separate the minerals, while the difference after the treatment is more than sufficient for strong magnetic separation.
This experiment shows that high-value ceramic material can be recycled despite very severe infiltration of another mineral than the ceramic mineral or minerals, and that the separated ceramic material can be reused to produce high-value ceramic material. The properties of the cyclone can be varied in order to adapt it to the input material and the desired output material through a testing carried out by one skilled in the arts of the axial positions of the vortex collector 15 and the size of the exit restriction 21.
Naturally occurring ilmenite sand was processed in the cyclone two times and subsequently subjected to magnetic separation. In this manner, sand particles that did not contain chrome oxide were separated from sand particles that did contain chrome oxide in that the different sand particles were magnetised to different degrees. This separation could not be carried out by strong magnetic processing of the sand in its natural state. The moist sand was also dried in the cyclone. A certain degree of crushing of the sand is also achieved and this crushing can be regulated in the same way as in Example 1. It is possible that the sand needs to be processed only once during production, following adjustment of the cyclone by one skilled in the arts. The examples given above are only examples of the invention. The invention can be applied in innumerable other fields. It is generally the case for the invention that a mixture of materials A, B, C, D is added to a cyclone device 10 according to the previous description, whereby the cyclone device breaks the mixture of materials down into smaller fractions and dries the mixture of materials, and it modifies (increases) the magnetic properties of the materials. The milled mixture of materials A-D that leaves the cyclone device is further processed, with or without intermediate steps such as transport or sieving, etc., by means of magnetic separation in which a number of magnets M1,M2,M3,M4 of different strengths are used. It is appropriate to use electromagnets, the field strengths of which can be adjusted.
That which has just been described is shown schematically in
It is possible with the method according to the invention to carry out magnetic separation of mixtures of materials that would previously have been impossible to separate due to the similar magnetic properties of the materials. The crushing effect of the cyclone device and its ability to modify magnetisations can, among other things, be regulated with the aid of 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 modification of the magnetic properties of the materials are adjusted according to the demands of the subsequent magnetic separation.
Thus, the invention is not restricted to the illustrated and described embodiments, since changes and modifications are possible within the scope of the accompanying claims.
Number | Date | Country | Kind |
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SE 0401164-9 | May 2004 | SE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SE05/00638 | 5/2/2005 | WO | 11/1/2006 |