Nonmagnetic particles

Most iron-ore-concentrating drums are applied ia a multidmm configuration in order to obtain maximum rejection of nonmagnetic particles. In cobbing service, two dmms are typical but as many as four have been used. These dmm concentrators incorporate a repulping box ahead of each dmm in order to provide the next dmm with a feed that can accomplish nonmagnetic rejection. 

Finishers. Magnetic finishing dmms are designed to produce the highest possible iron content in the concentrate. Typically, the feed size has been reduced to a nominal size of —74 fim (—200 mesh) or —44 fim (—325 mesh) in a ball mill circuit. The feed tank and feed arrangement of the finisher separator is usually of the semicountercurrent design. The objective is to disperse the feed particles in order to obtain maximum rejection of nonmagnetic particles. Both 762 and 914 mm dia dmms have been used in finisher appHcations. Dmm covers frequendy are not used in finisher constmction because of the material size. 

D assemblies of magnetic nanoparticles are formed if solntions of the corresponding particles are slowly reduced in volume or by careful destabilization of a solution by letting slowly diffuse a nonsolvent into the solution to get an oversaturation. Such procedures are in principle well known as crystallisation techniques also for nonmagnetic particles. 3D assemblies of up to several micrometers of cobalt," nickel," FePt," " or CoPtj" have been generated by one of these traditional routes. 

Magnetic Head Pulley. This equipment uses the principle of magnetic particles pinning on the carrier, which carries the particles into the magnetic field (see Figure 17). After separation, ferrous metallic and nonmagnetic particles are carried onto conveyor belts and, subsequently, to bins or hoppers. This... 

Prior to their encapsulation, the magnetic nanoparticles must be thoroughly dispersed, which is a much more difficult task than with nonmagnetic particles. Indeed, the prevention of agglomeration is due to balancing not only the gravitation-... 

A FIGURE 10.8 Magnetic and nonmagnetic particies Magnetic particles attract one another, excluding nonmagnetic particles. This behavior is analogous to that of polar and nonpolar molecules. 

M FIGURE 10.9 Polar and nonpolar molecules A mixture of polar and nonpolar molecules, like a mixture of magnetic and nonmagnetic particles, separates into distinct regions because the polar molecules attract one another, excluding the nonpolar ones. Question Can you think of some examples of this behavior ... 

Briefly, two major strategies have been envisioned one that uses preformed nonmagnetic particles, and the other incorporating the magnetic material (i.e., iron oxide) during the polymerization process leading to the composite particle formafion. 

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