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Five sulfide mine tailings coming from the Joutel mine tailing ponds (Quebec, Canada) were tested by the humidity cell test (30 to 52 cycles duration) and the column test (11 to 12 cycles duration). The objectives of this study were twofold. First, there was the determination of the tailings acid generation potential for site reclamation. Second, there was the kinetic test comparison for understanding the tailings geochemical behavior under different test conditions. The samples used had a wide diversity in terms of acid-generation potential, particle size distribution, and parameters influencing reaction rates. Leachates produced remained at a near neutral pH for the duration of the tests. Evolution of the main elements involved in the dissolution processes demonstrated neutralization by carbonates as a response to the acid generated by sulfide oxidation. Depletion rates given by sulfates are higher for the humidity cell tests when compared to those obtained for the column tests. This is consistent with most studies to date, the humidity cell test being considered as more severe. However, by taking the ratio between cumulative elements coming from neutralization and the ones coming from oxidation, similar curves (named herein oxidation -neutralization curves) for all tests were obtained. These results show that overall geochemical behavior of the tailings is similar at near neutral pH for both types of tests. With this interpretation method, the acid-generation potential of the Joutel tailings were tested and compared to the static test results to constrain their uncertainty zone with regard to the studied tailings. The tailings geochemical behavior (carbonate dissolution response to sulfide oxidation) at near neutral pH condition appears slightly dependent of test conditions under certain hypothesis. [ABSTRACT FROM AUTHOR]

Abstract: Sorption phenomena are known to play significant roles in metal mobility in mine drainage waters. The present study focuses on sorption phenomena controlling Ni concentrations in contaminated neutral drainage issued from the waste rock piles of the Tio mine, a hematite–ilmenite deposit near Havre-Saint-Pierre, Québec, Canada exploited by Rio Tinto Iron and Titanium. Batch sorption tests were conducted on waste rock samples of different composition and degree of alteration, as well as on the main mineral phases purified from the waste rocks. Sorbed phases were submitted to sequential extractions, XPS and DRIFT studies for further interpretation of sorption phenomena. The results from the present study confirm that sorption phenomena play a significant role in the Tio mine waste rocks, and that the main sorbent phases are the residual ilmenite ore in waste rocks, as well as plagioclase, the main gangue mineral. Sequential extractions suggest that most sorption sites are associated with reducible fractions, and XPS results indicate that Ni is sorbed as the hydroxide Ni(OH)2. The results from the present study provide useful information on sorption phenomena involved in the Tio mine waste rocks and enable further interpretation of Ni geochemistry in contaminated neutral drainage. [ABSTRACT FROM AUTHOR]