Recycling REEs in Magnets
Each of the following methods is suited for magnets of differing composition found in various devices and in different environments. They are as follows: Direct re-use, Reprocessing, Hydrometallurgical, Pyrometallurgical, and Gas-phase extraction.
Direct Re-use is the most economical method as it requires very little energy and generates no waste. It is useful for only large magnets in electric vehicles and wind turbines
Reprocessing of Alloys is especially suited for hard drives (magnets with little compositional variations), generates no waste r and requires minimal energy input. It is not suited for oxidized magnets.
Hydrometallurgical Method: Applicable to all types of magnet compositions, and oxidized alloys, but it requires many steps, generates large amounts of waste chemicals and consumes large amounts of water
Pyrometallurgical Methods: (Electrostatic refining; Liquid Metal Extraction; Glass Slag Method; Direct Melting).
These processes are applicable to all magnet compositions, generate no water waste, and require fewer processing steps than Hydrometallurgical methods. Direct melting of alloys facilitates the extraction of REE in metallic state. The processes use large amounts of energy and generate considerable solid waste. They cannot be used on oxidized magnets.
Gas Phase Extraction Methods: Applicable to all types of magnet compositions, oxidized and non-oxidized alloys and generates no wastewater. Process consumes large quantities of Chlorine gas and generates corrosive Aluminum Chloride.
Recycling REEs in Nickel Metal Hydride Batteries
Hydrometallurgical methods:
Possible to recycle and market different waste fractions (i.e. cathodes, anode materials, metal casings), requires minimal energy input, however dismantling and separating components requires many steps and consumes large quantities of chemicals.
Pyrometallurgical methods: A well-developed process that recovers energy from plastic castings and other organic components, but furnace is a major investment: REEs are extracted from slag and require additional separation.
Recycling REEs in Lamp Phosphors
Direct Re-use: This is a very simple method requiring no chemical processing. However, it is only suited to one type of fluorescent lamp since different phosphor mixtures are used in different lamps and phosphors deteriorate over the lifetime of the lamp.
Separation of phosphors in individual components: A relatively simple process that consumes limited amounts of chemicals. Pure phosphor fractions are very difficult to obtain, separation may change phosphor particle size and phosphors deteriorate over the lifetime of the lamp.
Recovery of REE content: Provides pure earth oxides that can be used in other applications, is applicable to all phosphor mixtures. Process requires many steps and consumes large amounts of chemicals and generates large quantities of water.
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