Buffering Copper Tailings Acid Mine Drainage: Modeling and Testing at Fushë Arrëz Flotation Plant, Albania

Abstract

The beneficiation process of sulfide ores has the inevitable consequence of generating huge amounts of tailings highly enriched in sulfur, thus inducing acid mine drainage (AMD) and the release of potentially toxic elements. The aim of the work was to define the most suitable procedures for buffering acid drainage waters through the addition of commercial CaCO3 paste, provided by UNICALCE. High- and low-pyrite tailing samples were collected at the copper enrichment plant of Fushë Arrëz (Northern Albania copper mining district). They were used for leaching and buffering tests, whose leachates and precipitation products were characterized by ICP-MS, chromatographic, XRD and TEM analyses. In addition, a geochemical model was developed in order to predict the pH trend of the leachate as a function of the addition of CaCO3. The results show the good buffering capacity of CaCO3, accurately predicted by the geochemical model. A drastic reduction in metals in the solution can be easily attained for low-pyrite samples, whereas high amounts of buffering agent are required to reach similar metals concentration reduction in high-pyrite. Precipitates are dominated by oxyhidroxides, followed by sulfates and hydrosilicates, but TEM showed also the presence of nanocrystalline and amorphous phases.

Recycling Feldspar Mining Waste as Buffering Agent for Acid Mine Drainage Mitigation

“…In order to compare the FLS results with the buffering tests conducted with calcite on the similarly acidic mine leachate waters from Fushe Arrez (Albania: samples FA3 and FA5) by Cocomazzi et al [21], the buffering curves were adjusted to 100% CaCO3, using the FLS CaCO3 content (Figure 5b). In these conditions of equivalent calcium carbonate, FLS is more efficient than the calcite buffer used in Cocomazzi et al [21]: both FS5 and FS11 require lower amounts of buffer to exceed the pH 6 threshold than FA3, even though the initial pH is lower; FS5, too, requires much less equivalent FLS buffer than FA4, whose initial pH is just slightly lower. The results confirm that feldspar provides a minor but clearly detectable contribution to buffering.…”

Chemometrics of the Environment: Hydrochemical Characterization of Groundwater in Lioua plain (North Africa) using Time Series and Multivariate Statistical Analysis

“…Alkalinity is commonly related to hardness, as the main alkalinity source often comes from carbonate rocks (limestone), made up mostly of CaCO3 [58,59]. It is known that the process of buffering calcite is dominant in the pH range of 6.5-7.5 [60].…”