In the production of fertilisers and commodity metals large amounts of stabilised waste is generated. Conventionally, manufacturing is targeted at the recovery of economically and technically most attractive key elements while the inorganic waste stream will gather all the other added-value chemical quantities. For example, substantial amounts of rare earth metals, which are increasingly used in various modern technologies including cleantech and photonics are present in phosphogypsum, the voluminous waste of the worldwide fertiliser industry. The waste heaps, while generally stabilised against weathering, appear usually granular or even as powder-like fines. Thus they represent a readily comminuted raw material for innovative mechanical, hydrometallurgical, biohydrometallurgical and pyrometallurgical techniques to recover considerable amounts of valuable metals and metal concentrates.
Keywords: phosphogypsum, fertilisers hydrometallurgy, rare earth metals, leaching, sorption, anaerobic, sulphides