Mineral precipitation experiments from an acid mine river: Rio Tinto, South West Spain

T Buckby, S Black, M L Coleman, M E Hodson

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The Rio Tinto region, in south west Spain, is a highly significant historical mining area within the Iberian Pyrite Belt. The Rio Tinto flows over approximately 70 - 80 km south from its source, in the Sierra Aracena, to the Huelva Estuary before emptying into the Gulf of Cadiz. The river flows through a floodplain of mining waste, draining an area of approximately 1,670 km(2). The Rio Tinto has a low pH (1.9-3.8), a deep red-brown colour and high dissolved metal contents [Fe (7200 ppm) Mg (1200 ppm), Al (2000 ppm)], along its entire 70 - 80 kin length. Both biotic and abiotic processes operate in the Rio Tinto system to produce Fe-bearing precipitates. The iron-oxidising bacteria Thiobacillus ferrooxidans and Leptospirillum ferrooxidans catalyse the oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+), which results in the precipitation of ferric (oxy)hydroxides. Additional Fe-bearing minerals such as copiapite [Fe2+Fe43+(SO4)(6)(OH)(2 .)20H(2)O] and coquimbite [Fe-2(3+)(SO4)(3 .)9H(2)O], precipitated on the floodplain are thought to result from evaporation. Controlled analogue laboratory-based experiments have been successfully conducted to simulate the chemical processes occurring in the Rio Tinto. Furthermore, the precipitates produced in the laboratory are similar, both mineralogically and chemically, to those observed on and around the floodplains of Rio Tinto. Laboratory experiments indicate mineral precipitates act as secondary storage reservoirs for the absorption of metals, which are subsequently released during flooding events.

Original languageEnglish
Title of host publicationWater-Rock Interactions
EditorsR Cidu
Place of PublicationLeiden
Number of pages4
Volume1 and 2
ISBN (Print)90-2651-824-2
Publication statusPublished - 2001
Event10th International Symposium on Water-Rock Interaction - BILLASIMIUS
Duration: 10 Jul 200115 Jul 2001


Conference10th International Symposium on Water-Rock Interaction

Cite this