NdFeB based permanent magnets how to Separate

It is believed that permanent magnets have been used for compasses by the Chinese since ~2500BC. However, it was only in the early twentieth century that high carbon steels and then tungsten / chromium containing steels replaced lodestone as the best available permanent magnet material. These magnets were permanent magnets due to the pinning of domain walls by dislocations and inclusions. The movement of dislocations within a material is often hindered by the same factors that effect the motion of domain walls and as a consequence these steels are mechanically very hard and are the origin of the term hard magnetic. These magnets had an energy product of approximately 8kJm-3.
Magnetic materials encompass a wide variety of materials, which are used in a diverse range of applications. Magnetic materials are utilised in the creation and distribution of electricity, and, in most cases, in the appliances that use that electricity. They are used for the storage of data on audio and video tape as well as on computer disks. In the world of medicine, they are used in body scanners as well as a range of applications where they are attached to or implanted into the body. The home entertainment market relies on magnetic materials in applications such as PCs, CD players, televisions, games consoles and loud speakers.
It is difficult to imagine a world without magnetic materials and they are becoming more important in the development of modern society. The need for efficient generation and use of electricity is dependent on improved magnetic materials and designs. Non-polluting electric vehicles will rely on efficient motors utilising advanced magnetic materials. The telecommunications industry is always striving for faster data transmission and miniaturisation of devices, both of which require development of improved magnetic materials.


Hazards

The greater force exerted by rare earth magnets creates hazards that are not seen with other types of magnet. Neodymium magnets larger than a few centimeters are strong enough to cause injuries to body parts pinched between two magnets, or a magnet and a metal surface, even causing broken bones.[2] Magnets allowed to get too near each other can strike each other with enough force to chip and shatter the brittle material, and the flying chips can cause injuries. There have even been cases where young children that have swallowed several magnets have had a fold of the digestive tract pinched between the magnets, causing injury or death.[3] The stronger magnetic fields can be hazardous also, and can erase magnetic media such as hard disks and credit cards, and magnetize the shadow masks of CRT type monitors at a significant distance.


References:
2.) Swain, Frank (March 6, 2009). "How to remove a finger with two super magnets". The Sciencepunk Blog. Seed Media Group LLC. Retrieved 2009-06-28.
3.) Magnet Safety Alert". U.S. Consumer Product Safety Commission. Retrieved 7 August 2009.