the purpose of the process can be seen clearly in all the embodiments illustrated . to begin with , material 1 to be sorted , comprising a mixture of particles of varying electrical conductance , is fed in from above . in these purely diagrammatic drawings , the particles 2 with high electrical conductance are shown as solid triangles , while the particles 3 with low electrical conductance are represented by outline circles . at the end of the process , the particles 2 with high conductance and the particles 3 with low conductance are separate and reappear in different positions . firstly , a charging means 11 can be seen at the top left - hand side , whereby the material 1 to be sorted is transferred to a channel conveyor 15 . the function of the conveyor 15 , which may be a vibrating channel , is to even out the flow of material and possibly extract undesirable components from the outset . instead of a channel conveyor 15 there may be a conveyor belt 15 b as in the fig4 or fig7 embodiment . ferrous metals may , for example , be taken out in this area , as they might cause trouble during the subsequent separation of non - ferrous metals from plastics and other electrically non - conductive or hardly conductive materials in accordance with the invention . on the one hand , ferrous metals can be removed relatively easily owing to their ferromagnetic properties , and there are many known devices that may be used for this purpose . on the other hand , these very properties of extremely strong magnetism interfere with further differentiation . the channel conveyor 15 or conveyor belt 15 b then feeds the material 1 to be sorted , in its still unsorted condition , to a conveyor 20 . in the embodiments in fig1 - 3 , this is a belt 20 a and in the fig4 - 5 or fig6 - 9 versions , this is a channel conveyor 20 b . from this position onwards , there is a difference between the embodiments ( a ) in fig1 ( b ) in fig2 - 3 , ( c ) in fig4 - 5 and 6 - 9 , and ( d ) fig1 - 14 . in fig1 the conveyor belt 20 a comprises an upper run 21 and a lower run 22 and moves over two drums 23 , 24 . it is driven and moves counter - clockwise in the view shown , with the upper run 21 of the belt going to the left in the direction 26 . the feed point 28 , around which the particles of material 1 fed from the channel conveyor 15 land on the surface of the conveyor belt 20 a , is above the right - hand drum 24 in fig1 . the magnetic system 30 is located inside the drum 24 but eccentrically from its axis and very precisely below the feed point 28 . it may , for example , be constructed in accordance with de 4 323 932 ci or in a different , traditional form . the system 30 shown is shaped as a cylindrical drum with a horizontal axis of rotation and with the drum turning clockwise . the direction 36 in which the surface of the magnetic system 30 moves in the area below the feed point 28 , i . e . below the conveyor belt 20 a , is thus exactly opposite the direction 26 in which the conveyor belt 20 a moves in that area . a particle of either higher or lower electrical conductance which drops off the channel conveyor 15 onto the conveyor belt 20 a will therefore be subject to the effect of two forces above the belt 20 a : firstly the flows induced by the magnetic lines , tending to pull it to the right in fig1 and secondly the frictional forces of the belt 20 a , tending to move it to the left . if the particle is relatively highly conductive , the magnetic forces will prevail and will convey it in a parabolic trajectory to the right , into a collecting container 41 standing in that position . if the ratio of the electrical conductance of a particle to its density is very low and the extracting force therefore weak , the particle is carried along by the conveyor belt and will then drop into a second collecting container 42 , which is kept ready at the end of the conveyor in the region of the drum 23 . any particles which are hooked together , lie on top of each other or impede each other will spend a certain time above the still rotating magnetic system 30 , and thus under the influence of the two above - mentioned forces . the forces naturally act in different directions on such particles , causing them to be disentangled and finally conveyed away in the correct directions . even if a particle has started moving in the wrong direction , possibly through a small particle of one kind being entrained by a larger particle of the other kind , the effect of the two forces acting over a corresponding distance and thus a corresponding time is to reverse the movement , so that the entrained particle can move in the right direction once freed from the other particle . thus , incorrect separation is still reversible up to a certain point , unlike the situation when a separating wall is used . if the particle is a ferrous metal , i . e . a ferromagnetic material , it is attracted by the magnetic system . it moves with the conveyor belt and hence with the less conductive particles and is thus separated from the non - ferrous metals . if desired , it may be separated from the less conductive particles , as it tends to remain on the belt through magnetic attraction . however ferrous metals can be extracted differently , and this is preferably done at a preliminary stage . in fig2 the mode of operation is the same as in fig1 although the conveyor belt 20 a with its upper run 21 and lower run 22 is guided around three drums 23 , 24 and 25 and is held by the two outer drums 23 and 24 . the magnetic system 30 is located — again eccentrically — in the largest , central drum 25 . unlike the first embodiment , the direction of movement 26 of the conveyor belt shown here is to the right , while the direction of movement 36 of the surface of the magnetic system 30 is to the left , i . e . in the opposite direction . here , the feed point 28 for the particles 2 , 3 of material 1 to be sorted is located slightly more centrally on the conveyor belt 20 a , though also above the magnetic system 30 . the conveyor belt , or the forces exerted thereby , thus has a somewhat longer - lasting effect on the electrically conductive particles 2 , which were moved more or less directly into a parabolic trajectory in the first embodiment . in the fig3 embodiment , the mode of operation is substantially the same as in fig2 . here the magnetic system 30 is constructed so that it substantially fills the largest , central drum 25 . in addition , the left - hand drum is installed vertically adjustably , so that the inclination of the upper run 21 of the conveyor belt 20 a can also be adjusted , possibly according to the nature of the mixture of material fed in for sorting . an embodiment , which is not illustrated , should be mentioned , where the respective directions of movement 26 and 36 of the conveyor belt 20 a and the surface of the magnetic system 30 are at an angle to each other in addition to the movement in opposite directions . this may sometimes be of interest , as a third type of particle can be extracted if another force component is included . in the embodiment in fig4 and 5 , the direction of relative movement 26 and 36 of the conveyor 20 and the surface of the magnetic system 30 respectively is also different , though this is for particularly appropriate extraction of non - ferrous metals rather than for extraction of a third type of particle . as described above , the material 1 to be sorted is first taken to the feed point 28 by a conveyor belt 15 b . at the feed point 28 , the as yet unsorted material drops onto a channel conveyor 20 b . this can be made to convey the particles 2 , 3 of material 1 lying on it , e . g . by means of a vibrator ( not shown ) or simply by suitably slanting and inclining the conveyor . the magnetic system 30 is again arranged below the channel conveyor 20 b . in this case however , its axis of rotation is parallel with the direction in which the particles are conveyed on the conveyor 20 b . consequently the direction of movement 36 of the magnetic system 30 — or more specifically of its surface — is perpendicular to the direction of movement 26 of the material 1 on the conveyor 20 . in this way , the non - ferrous metals are thrust laterally downwards in this same direction of movement 36 by the conveyor 20 , or here the channel conveyor 20 b , and drop into a collecting container 41 standing next to the conveyor 20 b . the other components of the material 1 however travel to the end of the conveyor 20 b and only drop into a collecting container 42 when they reach the end . in the diagrammatic section and elevation in fig4 this process can be seen as taking place and how it would appear from the right in fig5 . as indicated in the drawing , the conveyor 20 or the channel conveyor 20 b is also displaceable and adjustable both vertically and laterally . with this precise adjustment it may even be possible to separate different non - ferrous metals from each other on the conveyor 20 , e . g . to separate aluminum and tin , which practitioners have hitherto thought impossible . the vertical adjustability and lateral displaceability of the channel conveyor relative to the magnetic system 30 may in fact bring the forces acting on the different components of the material 1 into play in such a way that certain forces are sufficient to push a specific type of material down from the conveyor and leave another type on it . the embodiment in fig6 to 9 is similarly designed to that in fig4 and 5 . a second magnetic system 38 is additionally provided therein , with a direction of movement 39 for the surface above the conveyor 20 , which is in this embodiment a channel conveyor 20 b . in this way , the effect of the two magnetic systems 30 and 38 on the particles moving between them is made much more equal . this is partly because the second magnetic system 38 above the channel conveyor 20 b can now reliably influence rolling or rebounding particles of material 1 , which could hitherto still evade action by the first magnetic system 30 or which were difficult to sort because of their rebounding action and other particular irregularities . the stronger effect of the two magnetic systems is shown graphically by the larger angles in fig9 . the axes of the two magnetic systems 30 and 38 are parallel with each other and also with the conveying direction on the conveyor 20 b . they could possibly be at certain angles , especially if additional , possibly complex sorting effects seem appropriate . thus , particle separation may even be carried out with waste materials including lead being sorted so that the lead containing particles are separated from the others . it might even be possible to sluice out non - ferrous metals such as gold or silver from sand . the embodiment in fig1 and 11 , like that in fig4 and 5 , has a channel conveyor 20 b with a non - level base 27 . in this case however , the non - level base 27 is not only slightly raised at the center , but the whole base is curved upwardly like a segment of a circle . hence the particles come particularly close to the magnetic field , which is thus utilized more effectively . the drum 30 , which is immediately below the particles , rotates transversely to their conveying direction , so that particles of one type gather in the relatively acute angle formed between the base 27 and one sidewall , and particles of the other type gather at exactly the opposite side . here again , parts of the sidewall may of course be specifically left out , so that particles can be channeled out if this seems appropriate and if the materials definitely contain no particles , which would then tend to cling to the drum surface . fig1 and 13 show another embodiment in which a conveyor belt 20 a rather than a channel conveyor moves , its conveying direction 26 likewise being perpendicular to the direction of movement 36 of the drum surface . similar advantages are obtained with the belt construction . in the embodiment shown in fig1 fluid from a fluid supply means 50 , e . g . air from an appropriate nozzle , is additionally applied to the particles 2 , 3 above the magnetic system . in this way , more detailed specifications for the sorting of the particles can be followed . this version may be combined with any of the other embodiments .