Great thanks to Matt Newby at First4Magnets in Nottinghamshire for taking time to share his knowledge of magents with me. Some of the questions I asked him were:
Do magnets occur naturally or are they all man made? How are magnets formed? How much energy goes into magnetising? Can magnets be demagnetised and remagnetised? Does a magnet weaken over time?
The below are from my notes. Any errors are mine.
Though there are natural elements with magnetic properties such as haematite, magnets as we understand them, are made. They are formed within a strong electro-magnetic field. The first permanent magnet created was called Alnico. It weakens over time and is magnetically fragile so its use was replaced by Ferrite magnets which are a bit stronger and resist demagnetisation more.
However in 1972, the Neodymium magnet was created which is powerful in comparison with negilible demagnetisation over a 100 years. In effect, its a true permanent magnet. The discovery of Neodymium magnets is mirrored by the advances in consumer electronics. Every speaker, phone and microphone has tiny neodymium magnets inside.
There is another permanent magnet called Samarium Cobalt which can actually function at higher operating temperatures than Neodymium but its not as strong.
Neodymium is a rare earth metail that is mined in the Far East. It occurs within a compound from which it needs to be extracted. The magnet is made of neodymium, iron, boron and trace elements which are powder compressed under high pressure into a mould which is then subjected to a very high magnetic field. After this its cooled, plated, coated, shaped and magnetised again.
Neodymium magnets are difficult to recycle. But, as permanent magnets they are easy to re-use.
The neodymium magnets I've got for this project have a 5.5kg pull and are somewhere between awesome and frightening. They are so magical and amazing it would seem crazy to throw away a magnet ever again.