Refining
Refining involves separation of an element from its ore through the removal of impurities. So as to decrease the cost of transportation of the huge quantity of ore needed to refine, refining is often done at the mine itself. Refinement occurs through physical separation of the REEs by various chemical techniques, sometimes involving thousands of steps. Unfortunately, all REEs and their respective ores are different and require different chemical techniques for refining (depending on melting point and vapor pressure, as well as other physical properties of the element).
Typical techniques for refinement include milling, where ore is ground down to fine particles and then separated in a variety of ways, followed by cracking, where the it undergo a series of chemical treatments. Due to the large number of steps the REEs must go through to be purified requiring many different chemicals and reagents for these processes, there is a huge amount of toxic and radioactive waste generated from byproducts, which must be handled either through recycling, or by pumping it to a holding tank. The waste presents various health and environmental issues that must be dealt with at the mining site.
