Geochemical behavior of ultramafic waste rocks with carbon sequestration potential: a case study of the Dumont Nickel Project, Amos, Québec.
The geochemical behavior of ultramafic waste rocks and the effect of carbon sequestration by these waste rocks on the water drainage quality were investigated using laboratory-scale kinetic column tests on samples from the Dumont Nickel Project (RNC Minerals, QC, Canada). The test results demonstrated that atmospheric CO2dissolution induced the weathering of serpentine and brucite within the ultramafic rocks, generating high concentrations of Mg and HCO3-with pH values ranging between 9 and 10 in the leachates that promote the precipitation of secondary Mg carbonates. These alkaline pH values appear to have prevented the mobilization of many metals; Fe, Ni, Cu, and Zn were found at negligible concentrations in the leachates. Posttesting characterization using chemical analyses, diffuse reflectance infrared Fourier transform (DRIFT), and scanning electron microscope (SEM) observations confirmed the precipitation of secondary hydrated Mg carbonates as predicted by thermodynamic calculations. The formation of secondary Mg carbonates induced cementation of the waste particles, resulting in the development of a hardpan.
Research Institute in Mining and Environment (RIME), UQAT (Université du Québec en Abitibi-Témiscamingue), 445 boulevard de l'Université, Rouyn-Noranda, Québec, J9X 5E4, Canada.
El Hadji Babacar
EH
Kandji
Research Institute in Mining and Environment (RIME), UQAT (Université du Québec en Abitibi-Témiscamingue), 445 boulevard de l'Université, Rouyn-Noranda, Québec, J9X 5E4, Canada. benoit.plante@uqat.ca.
Benoit
B
Plante
Research Institute in Mining and Environment (RIME), UQAT (Université du Québec en Abitibi-Témiscamingue), 445 boulevard de l'Université, Rouyn-Noranda, Québec, J9X 5E4, Canada.
Bruno
B
Bussière
Department of Geology and Geological Engineering, Université Laval, Québec, Québec, G1V 0A6, Canada.
Georges
G
Beaudoin
RNC Minerals, 42 Rue Trudel, Amos, Québec, J9T 4N1, Canada.
Pierre-Philippe
PP
Dupont
D057965:Carbon Sequestration; D008906:Mining; D009532:Nickel; D011792:Quebec
D009532:Nickel
Alkaline drainage; Carbon sequestration; Hydrated magnesium carbonate; Kinetic column test; Prediction; Ultramafic waste rock