Stability of As- and Mn-sludge after neutral mine water treatment using Fe(VI) vs electrocoagulation.

The electrocoagulation (ECG) and ferrate (Fe(VI))-based processes are increasingly acknowledged as efficient for the simultaneous removal of As and Mn from synthetic and real mine effluents. Prior to design of full-scale applications, more information on the physicochemical, mineralogical, and environmental characterization of the produced sludge is required. The main objective of this study was to characterize and evaluate the leaching potential of problematic elements in As- and Mn-rich sludge produced during ECG or Fe(VI) treatment of circumneutral surrogate mine water.

Modeling the geochemical evolution of mine waters during mixing.

This study focuses on assessing the hydrogeochemical processes influencing the mobility of dissolved metal and metalloid species during mine effluent mixing. Field samples were collected to characterize effluents at an active gold mine located in the Abitibi Greenstone belt in western Québec, Canada. Controlled laboratory mixing experiments were further performed with real effluents.

Microbially Induced Calcium Carbonate Precipitation as a Bioremediation Technique for Mining Waste.

Mining waste represents a global issue due to its potential of generating acidic or alkaline leachate with high concentrations of metals and metalloids (metal(loid)s). Microbial-induced calcium carbonate precipitation (MICP) is an engineering tool used for remediation. MICP, induced via biological activity, aims to precipitate calcium carbonate (CaCO) or co-precipitate other metal carbonates (MCO).

Valorization potential of N-rich zeolite and moving bed biofilm reactor (MBBR) biomass in the revegetation of non-acid generating gold mine tailings.

Treatment of ammonia nitrogen (NH-N) in mine effluents generates N-rich residual materials, such as moving bed biofilm reactor (MBBR) biomass and spent zeolite. Using them as substitutes for mineral fertilizers in revegetation of mine tailings avoids disposal and contributes to a circular economy. The study evaluated the effect of MBBR biomass and N-rich zeolite amendments on above- and below-ground growth and foliar nutrient and trace element concentrations of a legume and several graminoid species grown on non-acid generating gold mine tailings.

Influence of ozone microbubble enhanced oxidation on mine effluent mixes and Daphnia magna toxicity.

The mining industry often must mix different kinds of water on the mine site during pre-treatment or post-treatment before the final discharge of the treated water to the environment. Microbubble ozonation has proven to be efficient in the removal of contaminants of concern from mine water, such as metals, metalloids, and nitrogen compounds, which can persist in the environment and entail toxicity issues. This study evaluated the efficiency of ozone microbubbles combined with lime precipitation on contaminant removal and its impact on toxicity for Daphnia magna with five different mine effluent mixes from an active mine site located in Abitibi-Témiscamingue, QC, Canada.

Improvement of water recovery from phosphate sludge at the M'Dhilla Mine, Tunisia.

In Tunisia, phosphate beneficiation from ores by the Gafsa Phosphate Company (GPC) is a water-intensive process that generates large amounts of sludge. Responsible mining minimizes water use and prioritizes its recycling and reuse to limit the impact on water resources. Recovery of water from the phosphate sludge (PS) using the densification with adapted flocculants-a low-energy consuming process-is plausible for efficient management of water resources.

Electro-Fenton treatment of contaminated mine water to decrease thiosalts toxicity to Daphnia magna.

Treatment of organic contaminants using the electro-Fenton (EF) process is efficient but generates toxic by-products. The aim of the present study was to assess the residual toxicity associated to the treatment of real mine effluents using EF and to perform a preliminary techno-economic analysis to compare the costs of different techniques. Two mine effluents from northern Quebec with different concentrations of thiosalts (ME and ME) were tested for acute toxicity to Daphnia magna, before and after EF treatment.

Passive multi-unit field-pilot for acid mine drainage remediation: Performance and environmental assessment of post-treatment solid waste.

This study evaluated the performance of a passive multi-unit field-pilot operating for 16 months to treat acid mine drainage (AMD) from a coal mine in Colombia Andean Paramo. The multi-unit field-pilot involved a combination of a pre-treatment unit (550 L) filled with dispersed alkaline substrate (DAS), and six passive biochemical reactors (PBRs; 220 L) under two configurations: open (PBRs-A) and closed (PBRs-B) to the atmosphere. The AMD quality was 1200 ± 91 mg L Fe, 38.

Passive treatment of acid mine drainage from the Sidi-Kamber mine wastes (Mediterranean coastline, Algeria) using neighbouring phosphate material from the Djebel Onk mine.

Passive abiotic treatment of acid mine drainage (AMD) was investigated using phosphate mining residuals (raw low-grade phosphate ore, phosphatic limestone wastes, and phosphate mine tailings) from the Djebel Onk mine, Algeria. Laboratory batch tests were performed using the main expected lithologies of phosphate materials in contact with synthetic AMD, which had a low pH (3.08) and contained high concentrations of Fe (600 mg/L), Mn (40 mg/L), Mg (10 mg/L), Zn (20 mg/L), Cu (25 mg/L), As (50 mg/L), and sulfate (3700 mg/L).

Behaviour of flotation tailings from a rare earth element deposit at high salinity.

Various rare earth element (REE) deposits hosted by carbonatite complexes have been identified in southern (Montviel, Niobec) and northern Quebec (Eldor deposit). During the winter in Quebec, the use of road salts to facilitate transportation on the mine site and/or avoid water freezing during mine operation may be necessary. The sources of salinity can be diverse on a mine site: process water, precipitation, alteration of minerals in the soil.

Electro-Fenton beyond the Degradation of Organics: Treatment of Thiosalts in Contaminated Mine Water.

Electro-Fenton (EF) is an emerging technology with well-known outstanding oxidation power; yet, its application to the treatment of inorganic contaminants has been largely disregarded. Thiosalts are contaminants of emerging concern in mine water, responsible for delayed acidity in natural waterways. In this study, EF was used to treat thiosalts in synthetic and real mine water.

Removal of nickel from neutral mine drainage using peat-calcite, compost, and wood ash in column reactors.

The effectiveness of compost, peat-calcite, and wood ash to remove Ni from a circum-neutral-contaminated mine water was tested in continuous flow experiments. Materials were compared in 4.8-L columns at hydraulic residence times (HRT) of ∼ 16.

Manganese removal processes and geochemical behavior in residues from passive treatment of mine drainage.

Efficiency of Mn passive treatment from mine drainage (MD) is limited, in the presence of Fe, because of the wide stability field of dissolved Mn(II) species. Physicochemical and mineralogical characterization, as well as static leaching tests at pH 7 (CTEU-9) of four samples were performed to assess Mn immobilization processes from MD and post-treatment stability of residues. Samples consisted of half-calcined dolomite, from three column reactors that treated Mn in MD.

Assessment of the leaching potential of flotation tailings from rare earth mineral extraction in cold climates.

Increasing use of rare earth elements (REEs) in modern technologies and existing or expected imbalances between demand and supply have led many countries, including Canada, to consider the exploitation of their own REEs primary sources. The objective of this study is a thorough characterization of the flotation tailings generated during the pre-concentration of REEs from a carbonatite type deposit with the aim of predicting their geochemical behaviour over time. These tailings were characterized based on physicochemical and mineralogical properties.

Performances of stabilization/solidification process of acid mine drainage passive treatment residues: Assessment of the environmental and mechanical behaviors.

Residues from passive treatment of acid mine drainage (AMD) have variable chemical stability and could regenerate contaminated drainage. Stabilization/solidification (S/S) can prevent contaminant leaching. Residues were collected from a tri-step AMD field passive treatment system, operated for 6 years at the reclaimed Lorraine mine site, Quebec, Canada.

Environmental behavior of metal-rich residues from the passive treatment of acid mine drainage.

In closed or abandoned mine sites, passive systems are often used for acid mine drainage (AMD) treatment. They generate metal-rich residues with variable chemical stability, which is rarely reported. The objective of the present study was to evaluate the potential mobility of contaminants (metals and sulfates) from AMD post-treatment residues to better anticipate their fate and enable their proper management.

Treatment efficiency of iron-rich acid mine drainage in a tri-unit pilot system.

Treatment efficiency of iron-rich acid mine drainage (AMD; pH 3, and 2 and 4 g/L Fe) was tested in a laboratory tri-unit pilot-scale reactor (2.65 m) for 1 year. The first unit consisted of a passive biochemical reactor (PBR1), filled with reactive mixture (50% of manure, sawdust, maple chips, compost, urea, sediment, and sand; 50% of calcite), with the aim to neutralize acidity and to partially remove metals.

Effect of the electrocoagulation process on the toxicity of gold mine effluents: A comparative assessment of Daphnia magna and Daphnia pulex.

Mine effluents must meet discharge criteria for both physicochemical parameters and toxicity. While chemical precipitation is efficient for the treatment of metallic elements in mine effluents, the removal of sulfates, as a source of salinity and potential toxicity, is limited by gypsum solubility. This study evaluated the efficiency of electrocoagulation (EC), an emerging process to treat mine water, in removing sulfates and acute toxicity in two gold mine effluents (E1 and E2), before and after treatment (Fe-electrodes, 30 min at 20 mA/cm, and pH near neutrality).

Salinity and low temperature effects on the performance of column biochemical reactors for the treatment of acidic and neutral mine drainage.

Passive biochemical reactors (PBRs) represent a promising option for the treatment of mine drainage. In this study, the influence of temperature (22 and 5 °C), salinity (0 and 20 g/L) and hydraulic retention time (HRT) on the efficiency of PBRs for the treatment of acidic and neutral mine drainage (AMD and NMD) was evaluated. To do so, eight 11 L PBRs were set-up and operated with vertically upward flow.

Stability of metal-rich residues from laboratory multi-step treatment system for ferriferous acid mine drainage.

Passive systems are often used for the treatment of acid mine drainage (AMD) on closed and abandoned mine sites. Metal-rich residues (solid precipitates) with variable chemical composition and physical properties can be generated. Their characterization is required to better anticipate the potential fate, including stability for disposal, potential recovery, or reuse.

Removal efficiency of As(V) and Sb(III) in contaminated neutral drainage by Fe-loaded biochar.

Performance of raw and two Fe-loaded biochars, produced either by evaporation (E-product, 26.9% Fe) or precipitation (P-product, 12.6% Fe), was evaluated in batch and column testing for As(V) and Sb(III) removal from contaminated neutral drainage (CND).

A review of the implications and challenges of manganese removal from mine drainage.

Manganese (Mn) is the third most abundant transition metal in the Earth's crust. Decades of increasing worldwide mining activities have inevitably led to the release of large amounts of this metal into the environment. Mine drainage, either acidic or neutral, often contains high levels of Mn, which have potentially detrimental effects on ecosystems and receiving water bodies.

Production, characterization, and potential of activated biochar as adsorbent for phenolic compounds from leachates in a lumber industry site.

There is growing interest in low-cost, efficient materials for the removal of organic contaminants in municipal and industrial effluents. In this study, the efficiency of biochar and activated biochar, as promising adsorbents for phenol removal, was investigated at high (up to 1500 mg L) and low concentrations (0.54 mg L) in synthetic and real effluents (from wood-residue deposits in Québec), respectively.

Performance assessment of laboratory and field-scale multi-step passive treatment of iron-rich acid mine drainage for design improvement.

Multi-step passive systems for the treatment of iron-rich acid mine drainage (Fe-rich AMD) perform satisfactorily at the laboratory scale. However, their field-scale application has revealed dissimilarities in performance, particularly with respect to hydraulic parameters. In this study, the assessment of factors potentially responsible for the variations in performance of laboratory and field-scale multi-step systems was undertaken.

Metals and metalloids treatment in contaminated neutral effluents using modified materials.

Circumneutral surface water and groundwater can contain hazardous concentrations of metals and metalloids that can threaten organisms in surrounding ecosystems. Extensive research has been conducted over the past two decades to prevent, limit, and treat water pollution. Among the currently available treatment options is the use of natural and residual materials, which is generally regarded as effective and inexpensive.