Hydrogeochemical Behavior of Reclaimed Highly Reactive Tailings, Part 1: Characterization of Reclamation Materials

Abstract

The production of solid mine wastes is an integral part of the extraction and metallurgical processing of ores. The reclamation of highly reactive mine waste, with low neutralizing potential, is still a significant challenge for the mining industry, particularly when natural soils are not available close to the site. Some solid mine wastes present interesting hydro-geotechnical properties which can be taken advantage of, particularly for being used in reclamation covers to control acid mine drainage. The main objective of this research was to evaluate the use of mining materials (i.e., tailings and waste rock) in a cover with capillary barrier effects (CCBE) to prevent acid mine drainage (AMD) from highly reactive tailings. The first part of the project reproduced in this article involves context and laboratory validation of mining materials as suitable for a CCBE, while the companion paper reports laboratory and field results of cover systems made with mining materials. The main conclusions of the Part 1 of this study were that the materials studied (low sulfide tailings and waste rocks) had the appropriate geochemical and hydrogeological properties for use as cover materials in a CCBE. Results also showed that the cover mining materials are not acid-generating and that the LaRonde tailings are highly reactive with pH close to 2, with high concentrations of metals and sulfates.

Hydrogeochemical Behavior of Reclaimed Highly Reactive Tailings, Part 2: Laboratory and Field Results of Covers Made with Mine Waste Materials

“…The TR were highly acid-generating, while the mine waste cover materials (TG-low-sulfide tailings, WP-potentially acid-generating waste rocks, and WL-non-acid-generating waste rocks) were non-acid-generating. The hydrogeological properties of materials were similar to those found in the literature for other tailings and waste rocks [22]. The contrast between the k sat values of the fine and coarse materials was nearly three orders of magnitude, and thus expected to create the desired capillary barrier effects.…”

“…Material characterizations for the reactive tailings (TR) and cover materials (i.e., low-sulfide tailings and waste rocks) were presented in Part 1 of this study [22]. Table 1 summarizes the most important mineralogical, geochemical, hydrogeological, and physical parameters of each material.…”

“…A total of 18 cycles (504 days) were applied to the laboratory column. Effluents from the column were recovered after a maximum flush time of 48 hours for each cycle and submitted to various physicochemical analyses [22].…”

“…A total of 18 cycles (504 days) were applied to the laboratory column. Effluents from the column were recovered after a maximum flush time of 48 hours for each cycle and submitted to various physicochemical analyses [22]. The laboratory column was equipped with 5TM and GS3 sensors and an Em50 data logger (version 4, Decagon Devices, Pullman, WA, United States) that recorded the volumetric water content (θ) at various depths in the tailings and waste rocks, respectively (Figure 2).…”

“…The periphery of the excavation was filled with waste rock to give the cells the shape of an inverted truncated pyramid. The interior sides of the cell were sloped (2H:1V) to obtain the desired size and geometry, lined with a geomembrane (Figure 3a), and a drainpipe was installed at the bottom to recover water drainage from the cell (see [22] for more details). The cell was filled with the same materials as the laboratory column from the bottom to the top: TR (1.00), WP (0.30), TG (0.60), and WL (0.30 m) (Figure 3b,c).…”