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

Alex Kalonji-Kabambi,Bruno Bussière,Isabelle Demers

doi:10.3390/min10070596

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.

Highlights

In recent decades, stricter regulations have forced the mining sector to better protect the environment both during and after operations
The three main cover with capillary barrier effects (CCBE) layers are: (1) the capillary break layer (CBL), which consists of a coarse-grained material that acts as a capillary break; (2) the moisture-retaining layer (MRL), which is made of a fine-grained material and is aimed at controlling fluid movement; and (3) the drainage layer (DL), which is made of a coarse-grained material, prevents evaporation, and favors water lateral drainage [10]
The main objective of this research was to study the hydrogeochemical behavior of highly reactive tailings protected by a CCBE made entirely of low sulfide mine wastes

Summary

Introduction

Stricter regulations have forced the mining sector to better protect the environment both during and after operations. One important environmental issue of the mining sector is the generation of acid mine drainage (AMD) from mine wastes such as tailings and waste rocks [1,2,3,4]. In order to control AMD generation, most current reclamation methods seek to control one or more of the main components involved: atmospheric oxygen, sulfide minerals, and water [5,6,7,8]. Oxygen barriers are recognized as the one of the most efficient approach to control the AMD generation [9] among which cover with capillary barrier effects (CCBE) made of multiple layers of soils or other geological materials is one of the preferred options. The three main CCBE layers are (from bottom to top): (1) the capillary break layer (CBL), which consists of a coarse-grained material that acts as a capillary break; (2) the moisture-retaining layer (MRL), which is made of a fine-grained material and is aimed at controlling fluid (gas and water) movement; and (3) the drainage layer (DL), which is made of a coarse-grained material, prevents evaporation, and favors water lateral drainage [10].

Objectives

Methods

Discussion

Conclusion