Selective magnetic separation of uranium and gold

Energetic and kinetic criteria for the selective magnetic separation of a useful mineral from a system containing several mineral species are derived, based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. It is shown that both criteria give similar predictions of the onset of coagulation and of the selectivity of magnetic separation. The best quality of magnetic concentration is achieved at a pH value that lies outside the interval between points of zero charge (PZC) of the minerals present, and the highest recovery of the useful mineral is achieved when the working pH value is as close as possible to the PZC of the valuable mineral. The magnetic field must be chosen in such a way that heterocoagulation between the useful mineral and the gangue is suppressed and homocoagulation of the valuable mineral particles is promoted. The predictions of the model are shown to be in very good agreement with the experimental results.