A rather negatively-oriented article recently highlighted the developments in the Rare Earth Mineral industry in China. Unfortunately the article is rather light on technical details, choosing to highlight the environmental impacts. According to the article there have been many ‘pirate’ operations extracting Rare Earth Elements (REE), and extraction techniques include in situ leaching where chemicals are pumped into soil to dissolve and extract the elements from the soil. It is mentioned that other extraction techniques are in use and under development with lower impacts.
As posted earlier, LKAB in Sweden is studying the recovery of REE from iron ore tailings, and NW Russia have existing commercial operations doing this. The waste chemical mentioned in the article on China, “ammoniacal nitrogen” sounds like a potential resource for fertiliser production, or at least can be treated in an analogous manner to the treatment of sulphate in mining waste water being studied in the SEESIMA project WP5.
An article with more technical detail on the Chinese REE industry can be found here, This article focuses on the ion absorption type of REE deposits, which are only found in China. Although only representing less than 3% of China’s REE deposits, they have a higher content of medium and heavy REE and simpler extraction, being easily extracted by ion exchange with ammonium sulphate solutions. This is the basis for the in situ leaching processes, which avoided the environmental impact of open excavation.