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Environmental assessment of mining related contamination - An integrated study combining mineralogy, geochemistry and biogeochemistry

English title mining related contamination - An integrated study combining mineralogy, geochemistry and biogeochemistry
Applicant Spangenberg Jorge
Number 103678
Funding scheme Project funding (Div. I-III)
Research institution Institut de Minéralogie et Géochimie Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geochemistry
Start/End 01.08.2004 - 31.03.2007
Approved amount 133'604.00
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Keywords (9)

ACID MINE DRAINAGE; TAILINGS IMPOUNDMENTS; PORPHYRY COPPER; CHUQUICAMATA; EL TENIENTE; HEAVY METALS; lipids; stable isotopes; organic acids

Lay Summary (English)

Lead
Lay summary
Tailings impoundments are well-known as producers of Acid Mine Drainage (AMD). The primary objective of the project was to study the mineralogy (XRF, XRD, DXRD, microscopy) and hydrogeochemistry (major and trace ions by ICPMS, HPIC, d2H(water); d18O(water), d34S(sulfate), d18O(sulfate)) of fresh tailings impoundments from the giant Cu-Mo porphyry deposits Chuquicamata (containing 86 Mt of Cu) and El Teniente (containing 75 Mt of Cu) in Chile. This study focuses on the first changes of the tailings chemistry to understand the formation and evolution of AMD. The adquired knowledge will help to prevent the formation of AMD in similar systems. At Talabre/ Chuquicamata, oxidation of sulfides in the tailings started rapidly after deposition due to the dry-out of the tailings. The pH dropped down from 10 (fresh tailings) to 4 paste pH of 5 years old tailings. Capillary transport formed at the surface an assemblage of water-soluble, heavy metal bearing sulfates. Renewed deposition cover this oxidized layer and change the environment from oxidizing to reducing environment. At Caren/El Teniente, the water-saturation of the tailings inhibited strong alteration of sulfides in the wet winter season. Only a slight drop-down of the pH with the age of tailings of the pH can be observed (pH 9.2 from fresh tailings to pH 7.9 at the oldest tailings, and from the surface to deeper levels). During the hot summer season, evaporative dry-out of the tailings surface accelerated the oxidation of sulfates at the surface and resulted in lower pH values than in the winter season and the precipitation of efflorescent salts, e.g. mirabilite.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute
Smuda Jochen

Associated projects

Number Title Start Funding scheme
115921 Geochemical processes in freshly deposited tailings from porphyry copper ore - An environmental study different climatic regions of Chile 01.04.2007 Project funding (Div. I-III)
66739 Environmental assessment of mining related contamination - An integrated study combining mineralogy, geochemistry and biogeochemistry 01.05.2002 Project funding (Div. I-III)

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