Soil Contaminated with Hazardous Waste Materials at Rio Tinto Mine (Spain) Is a Persistent Secondary Source of Acid and Heavy Metals to the Environment

Autor: Sandra Fernández-Landero, Juan Carlos Fernández-Caliani, María Inmaculada Giráldez, Emilio Morales, Cinta Barba-Brioso, Isabel González
Jazyk: angličtina
Rok vydání: 2023
Předmět:
Zdroj: Minerals; Volume 13; Issue 4; Pages: 456
ISSN: 2075-163X
DOI: 10.3390/min13040456
Popis: Mineralogical analysis and laboratory-based leaching tests coupled with speciation modeling were undertaken to quantify the potential for short-term acid generation and the release of trace elements from soils heavily contaminated with mine waste at Rio Tinto. Three different waste materials were considered as case studies: roasted pyrite, copper slags, and leached sulfide ores. The results showed elevated values of net acid generation (up to 663 mmol H+/kg), the major pools being potential sulfidic acidity and acidity retained in jarosite. Remarkable contents of As and toxic heavy metals were found especially in the slag-contaminated soil. Copper, Zn, and Pb were the most abundant metals in the acid leach solutions resulting from mine soil-water interaction, with peak values of 55.6 mg L−1, 2.77 mg L−1, and 2.62 mg L−1, respectively. Despite the high total contents of trace elements occurring in soil, the mobile fraction was limited to maximum release values of 12.60% for Cd and 10.27% for Cu, according to the test leaching. Speciation calculations indicated that free metal ions (M2+) and sulfate species (MSO40) accounted for most of the dissolved load. Acid soil drainage is a secondary source of acid and heavy metals in the mine site and, therefore, an effective land reclamation program should ensure that acidity and metal mobility are reduced to environmentally sustainable levels.
This research was supported by the Regional Government of Andalusia (Spain) and the European Regional Development Fund Andalusia 2014–2020 through Project P-18-TP-3503, in collaboration with DSM Soluciones Medioambientales.
Databáze: OpenAIRE
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