4:20 PM - 4:35 PM
[PCG21-15] A novel principle to separate and identify groups of solid particles in general using a facile magnetic circuit
Keywords:Diamagnetic material, , magnetic volume force,, magnetic separation,, paramagnetic material,, niobium magnet
The separation proceeds by a recently proposed mechanism . An external field B induces a small magnetization in a diamagnetic particle which is proportional to three parameters, namely χ, B and mass of particle m. The particle will translate in the direction of monotonically decreasing field by a field gradient force, because magnetization is induced in a opposite direction with respect to B. Considering an energy conservation rule, the variance of terminal velocity vT observed between the particle outside the field is uniquely determined by intrinsic χ value of material ; here particles are released at the same position. Accordingly, the released particles will be separated into different groups of materials as they translate in the direction of decreasing field . In a preliminary experiment, the Nd circuit was enclosed in a transparent vacuum chamber with the heterogeneous particles. The image of the translating particle was observed by a hi-vision camera that was set outside the chamber; χ value of individual particle was determined from vT that was obtained from the images. The short microgravity condition was produced inside a small box (inner area: 550 x 430 x 300 mm), which was used in a shaft having a height of 180 cm (duration < 0.5 s ) ; it is possible to reduce the effective size of the apparatus
Using a conventional mass spectrometer, it is difficult to identify the material of a solid particle without consuming the sample. In the case of an infrared optical analysis, material composition of the particle interior is difficult to detect when its diameter is larger than 100 microns. The proposed method of magnetic separation can overcome the above-mentioned limitations of the conventional methods. Hence the method may serve as a supplemental tool of material analysis in the future. The prototype apparatus developed in the present study has a rigid and compact structure, and operated by a simple principle that can be easily examined; its power consumption is small, and finally, analysis is completed without consuming sample. So far, the spec of the machine seems to be suitable for a remote sensing mission.
In the present report, the validity of the proposed method is examined based on the numerical data obtained in the extending experiments, where magnitude of field gradient is considerably enhanced. In order to put the system to a practical use, it is necessary to improve the resolution in separating two different materials that have small variance of χ values.
References  Hisayoshi, Uyeda Terada (2016) Sci Reps, 6, 38431; YouTube "Magnetic separation of general solid particles realised by a permanent magnet"
 Uyeda, Hisayoshi, Kanou, (2010) J. Phys. Soc. Jpn. 79, 064709,