REPROCESSING OF MINING WASTES : METAL RECOVERY AND ENVIRONMENTAL MITIGATION

Anne-Gwénaëlle Guezennec*, M. Save, F. Bodenan

Water, Environment & Ecotechnologies Division, BRGM - 3, av. Claude Guillemin, BP 36009, 45060 Orléans Cedex 2, France - +33 (0)2 38 64 31 36, [email protected]

ABSTRACT

Supplying and securing the mineral resources with minimum environmental footprint is a serious challenge, especially for the European Union which accounts for 25 to 30% of the world’s metal consumption but produces only approximately 3% of the world’s ore. European dependency on metal import is growing every year despite efforts in the development of recycling technologies and in material science. These tensions point out the need to associate the development of the recycling industry to the identification of new potential sources which could be used for the recovery of rare and valuable materials in order to close the gap in raw materials supplying. In this context, old waste deposits related to past mining and metallurgical activities are regularly cited as potential significant reserves of valuable metals. Following the rich mining history of France, there are currently some 300 mineral deposits mined or significantly explored. These are often associated with large quantities of ‘tailings’ which can be the source of major environmental and sanitary impacts. The paper focuses on one of these sites, a former Pb-Ag mine, and investigates the use of conventional mineral processing techniques as well as more sophisticated one (MGS) for metal recovery together with environmental mitigation. A laboratory study was first carried out to assess the metal recovery potential and to determine the required operational conditions. In a second step a continuous piloting operation was designed including separation, classification and concentration stages. Four tons of tailings were treated, which enable to determine the recovery of Pb and associated metals. A simple classification stage at 100 µm enables to recover 46% of lead in 8.6% of the initial mass of waste. Further concentration operations on the finest fraction (< 100 µm) increase the lead content up to 48% and the silver one up to 380 ppm.

KEYWORDS

Tailings, Lead, Silver, MGS, decontamination