Method of magnetizing nonmagnetic materials

A method for separating particles of a nonmagnetic material from an aqueous mixture comprising the steps of:

• rendering the surfaces of said particles magnetic by contacting with a magnetizing reagent comprising water containing particles of a magnetic material, each of said magnetic particles having a two layer surfactant coating including an inner layer and an outer layer, said inner layer covering said magnetic particle and being a monomolecular layer of a first water soluble, organic, heteropolar surfactant containing at least 3 carbon atoms and having a functional group on one end which forms a bond with said magnetic particle and a hydrophobic end, and said outer layer coating said inner layer and being monomolecular layer of a second water soluble, organic, heteropolar surfactant containing at least 3 carbon atoms and having a hydrophobic end which is bonded to the hydrophobic end of said first surfactant and a functional group on the other end capable of bonding with said nonmagnetic particles;
• and
• subjecting the mixture to a magnetic separation to cause said magnetized particles to be separated therefrom.