Sorting substances of different hardnesses - by encrusting softer substance with magnetic particles and subjecting product to magnetic field

摘要

A process for sorting substances of different surface hardness consists of adding magnetic particles to the substances treating the whole so as to encrust the less hard substance with a part of the magnetic particles, eliminating the particles which have not entrusted and subjecting the product to the action of a magnetic field. The encrusting is pref. carried out in a fragmentation appts. of the group operating by compression, percussion, shearing, chopping, cutting. It may be carried out at a temp. above ambient to modify the superficial hardness. The process can be used in all cases where economical sorting of natural or artificial substances, metallic or non-metallic, is required. Mixtures of copper, lead or aluminium, lead resulting from the granulation of recovered electric cables are easily treated. It is most useful when only the hardest substance is to be isolated because that is not encrusted and does not have to be further treated.