Investigation of metal mobility in gold and silver mine tailings by single-step and sequential extractions

Abstract

Metal leachate from mine tailings has the potential to release toxic metals into the surrounding environment. A single-step extraction procedure mimicking rainwater and a three-step BCR sequential extraction procedure (acid, reducing and oxidizing conditions) were applied to gold (GMT) and silver (SMT) mine tailings. Major (Al, Ca, Fe, Mg, and Mn) and trace metals were monitored to better understand the mobility and geochemistry of these metals when exposed to various environmental leaching conditions. Rainwater extraction released only small quantities of metals, while the three-step BCR extraction was more effective in mobilizing metals from the tailings. Under the acidic conditions of BCR step 1, Ca, Mg, Cd, Cu, and Mn were released in high concentrations. The dissolution of Fe, Ca, and Mg were dominant along with Pb in step 2 (reducing conditions). In step 3 (oxidizing conditions), Fe was the most dominant species together with Co, Cu, Ni, and Se. A high fraction of Al, Be, Cr, Li, Mo, Sb, Tl, and V remained in the residue. From SMT, larger quantities of As, Ca, Cd, and Zn were released compared to GMT. The BCR extraction could be applied to tailings to predict the potential release of toxic metals from mine wastes; however, excessive amounts of Ca and Fe in the tailings could cause carry-overs and incomplete extraction and carry-overs, resulting in a misinterpretation of results.

Evaluation of surface water quality in basins of the Chilean Altiplano-Puna and implications for water treatment and monitoring

“…Mining activities significantly pollute rivers (Fan et al, 2022 ; Kumkrong et al, 2022 ). This is the case for the Río Lluta basin.…”

Ensuring the Quality of the Analytical Process in a Research Laboratory

“…Secondly, the requirement to choose a CRM with characteristics as close as possible to the studied material [8,9] is often not feasible if an appropriate CRM is not commercially available. Some of the methods for characterization of mine tailings or coal combustion by-products are reported to be verified by analyzing CRM of soils or lake sediments [2,10,11]. However, soil material differs in matrix composition, state of the analytes, or their speciation and concentration ranges from the target material, and it limits the possibility of fully studying the method behavior [11].…”

Comparative assessment of phytoavailable cadmium by using various extractants in texturally different contaminated soils during the growth of maize crop

“…Single and sequential extraction techniques in soils and sediments are widely used for analyzing the metal fractions and predicting their mobility and bioavailability (Jalali and Hurseresht, 2020;Kumkrong et al, 2022;Mbodji et al, 2022). The single extraction approach aims to dissolve a phase whose elemental content is readily mobilizable and, ideally, correlates with the bioavailability in plants.…”

“…The single extraction approach aims to dissolve a phase whose elemental content is readily mobilizable and, ideally, correlates with the bioavailability in plants. In the sequential extraction methods, a sample is subjected to a series of progressively harsher chemicals to dissolve forms that are becoming more and more resistant to dissolution (Kumkrong et al, 2022;Mbodji et al, 2022). Single extraction technique can be used to provide useful information on bioavailability and toxicity fractions of potentially harmful Cd metal that is present in the soil for plant uptake (Milicevic et al, 2017;Jalali and Hurseresht, 2020).…”

“…Metals bound to various mineral or organic phases can potentially be estimated more accurately using sequential extraction techniques (Abedin et al, 2012;Álvarez-Quintana et al, 2022). Sequential extraction methods are time-consuming and laborious methods as compared to single extraction method which uses a single extractant to extract the trace metal (Kumkrong et al, 2022;Mbodji et al, 2022). Several single extraction techniques which are using single extracting solvents such as neutral salts NaNO3, NH4AOc, and CaCl2 are used to evaluate the mobility and availability of Cd metal fractions in soil (Jalali and Hurseresht, 2020;Ma et al, 2020;Sihlahla et al, 2020).…”