Minerals

Editorial

4 pages, 205 KiB

Open AccessEditorial

Editorial for Special Issue “Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management”

by Carlito Baltazar Tabelin, Kyoungkeun Yoo and Jining Li

Minerals 2021, 11(8), 902; https://doi.org/10.3390/min11080902 - 20 Aug 2021

Cited by 3 | Viewed by 2293

Abstract

Climate change is one of the most pressing problems facing humanity this century [...] Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

Research

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19 pages, 9732 KiB

Open AccessArticle

The Role of Mineral Assemblages in The Environmental Impact of Cu-Sulfide Deposits: A Case Study from Norway

by Yulia Mun, Sabina Strmić Palinkaš and Kåre Kullerud

Minerals 2021, 11(6), 627; https://doi.org/10.3390/min11060627 - 12 Jun 2021

Cited by 3 | Viewed by 3297

Abstract

Metallic mineral deposits represent natural geochemical anomalies of economically valuable commodities but, at the same time, their weathering may have negative environmental implications. Cu-sulfide mineral deposits have been recognized as deposits with a particularly large environmental footprint. However, different Cu deposits may result [...] Read more.

Metallic mineral deposits represent natural geochemical anomalies of economically valuable commodities but, at the same time, their weathering may have negative environmental implications. Cu-sulfide mineral deposits have been recognized as deposits with a particularly large environmental footprint. However, different Cu deposits may result in significantly different environmental impacts, mostly depending on weathering conditions, but also on geological characteristics (mineralogy, geochemistry, host-rock lithology) of the Cu mineralization. This study presents new mineral and geochemical data from the Repparfjord Tectonic Window sediment-hosted Cu deposits and the Caledonian volcanogenic massive sulfides (VMS) deposits. The deposits share similar mineral features, with chalcopyrite and bornite as the main ore minerals, but they differ according to their trace element composition, gangue mineralogy, and host lithology. The studied sediment-hosted Cu deposits are depleted in most toxic metals and metalloids like Zn, As, Cd, and Hg, whereas the Røros Caledonian VMS mineralization brings elevated concentrations of Zn, Cd, In, Bi, As, and Cd. The conducted leaching experiments were set to simulate on-land and submarine weathering conditions. A high redox potential was confirmed as the main driving force in the destabilization of Cu-sulfides. Galvanic reactions may also contribute to the destabilization of minerals with low rest potentials, like sphalerite and pyrrhotite, even under near-neutral or slightly alkaline conditions. In addition, the presence of carbonates under near-neutral to slightly alkaline conditions may increase the reactivity of Cu sulfides and mobilize Cu, most likely as CuCO₃ (aq). Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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13 pages, 2286 KiB

Open AccessEditor’s ChoiceArticle

Performance Evaluation of Fe-Al Bimetallic Particles for the Removal of Potentially Toxic Elements from Combined Acid Mine Drainage-Effluents from Refractory Gold Ore Processing

by Elham Aghaei, Zexiang Wang, Bogale Tadesse, Carlito Baltazar Tabelin, Zakaria Quadir and Richard Diaz Alorro

Minerals 2021, 11(6), 590; https://doi.org/10.3390/min11060590 - 31 May 2021

Cited by 18 | Viewed by 4009

Abstract

Acid mine drainage (AMD) is a serious environmental issue associated with mining due to its acidic pH and potentially toxic elements (PTE) content. This study investigated the performance of the Fe-Al bimetallic particles for the treatment of combined AMD-gold processing effluents. Batch experiments [...] Read more.

Acid mine drainage (AMD) is a serious environmental issue associated with mining due to its acidic pH and potentially toxic elements (PTE) content. This study investigated the performance of the Fe-Al bimetallic particles for the treatment of combined AMD-gold processing effluents. Batch experiments were conducted in order to eliminate potentially toxic elements (including Hg, As, Cu, Pb, Ni, Zn, and Mn) from a simulated waste solution at various bimetal dosages (5, 10, and 20 g/L) and time intervals (0 to 90 min). The findings show that metal ions with greater electrode potentials than Fe and Al have higher affinities for electrons released from the bimetal. Therefore, a high removal (>95%) was obtained for Hg, As, Cu, and Pb using 20 g/L bimetal in 90 min. Higher uptakes of Hg, As, Cu, and Pb than Ni, Zn, and Mn also suggest that electrochemical reduction and adsorption by Fe-Al (oxy) hydroxides as the primary and secondary removal mechanisms, respectively. The total Al³⁺ dissolution in the experiments with a higher bimetal content (10 and 20 g/L) were insignificant, while a high release of Fe ions was recorded for various bimetal dosages. Although the secondary Fe pollution can be considered as a drawback of using the Fe-Al bimetal, this issue can be tackled by a simple neutralization and Fe precipitation process. A rapid increase in the solution pH (initial pH 2 to >5 in 90 min) was also observed, which means that bimetallic particles can act as a neutralizing agent in AMD treatment system and promote the precipitation of the dissolved metals. The presence of chloride ions in the system may cause akaganeite formation, which has shown a high removal capacity for PTE. Moreover, nitrate ions may affect the process by competing for the released electrons from the bimetal owing to their higher electrode potential than the metals. Finally, the Fe-Al bimetallic material showed promising results for AMD remediation by electrochemical reduction of PTE content, as well as acid-neutralization/metal precipitation. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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14 pages, 2286 KiB

Open AccessArticle

Genomic Analysis of a Newly Isolated Acidithiobacillus ferridurans JAGS Strain Reveals Its Adaptation to Acid Mine Drainage

by Jinjin Chen, Yilan Liu, Patrick Diep and Radhakrishnan Mahadevan

Minerals 2021, 11(1), 74; https://doi.org/10.3390/min11010074 - 13 Jan 2021

Cited by 16 | Viewed by 3535

Abstract

Acidithiobacillus ferridurans JAGS is a newly isolated acidophile from an acid mine drainage (AMD). The genome of isolate JAGS was sequenced and compared with eight other published genomes of Acidithiobacillus. The pairwise mutation distance (Mash) and average nucleotide identity (ANI) revealed that [...] Read more.

Acidithiobacillus ferridurans JAGS is a newly isolated acidophile from an acid mine drainage (AMD). The genome of isolate JAGS was sequenced and compared with eight other published genomes of Acidithiobacillus. The pairwise mutation distance (Mash) and average nucleotide identity (ANI) revealed that isolate JAGS had a close evolutionary relationship with A. ferridurans JCM18981, but whole-genome alignment showed that it had higher similarity in genomic structure with A. ferrooxidans species. Pan-genome analysis revealed that nine genomes were comprised of 4601 protein coding sequences, of which 43% were core genes (1982) and 23% were unique genes (1064). A. ferridurans species had more unique genes (205–246) than A. ferrooxidans species (21–234). Functional gene categorizations showed that A. ferridurans strains had a higher portion of genes involved in energy production and conversion while A. ferrooxidans had more for inorganic ion transport and metabolism. A high abundance of kdp, mer and ars genes, as well as mobile genetic elements, was found in isolate JAGS, which might contribute to its resistance to harsh environments. These findings expand our understanding of the evolutionary adaptation of Acidithiobacillus and indicate that A. ferridurans JAGS is a promising candidate for biomining and AMD biotreatment applications. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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17 pages, 5269 KiB

Open AccessArticle

Optimization of the Mix Formulation of Geopolymer Using Nickel-Laterite Mine Waste and Coal Fly Ash

by Alberto Longos, Jr., April Anne Tigue, Ithan Jessemar Dollente, Roy Alvin Malenab, Ivyleen Bernardo-Arugay, Hirofumi Hinode, Winarto Kurniawan and Michael Angelo Promentilla

Minerals 2020, 10(12), 1144; https://doi.org/10.3390/min10121144 - 21 Dec 2020

Cited by 26 | Viewed by 5108

Abstract

Geopolymer cement has been popularly studied nowadays compared to ordinary Portland cement because it demonstrated superior environmental advantages due to its lower carbon emissions and waste material utilization. This paper focuses on the formulation of geopolymer cement from nickel–laterite mine waste (NMW) and [...] Read more.

Geopolymer cement has been popularly studied nowadays compared to ordinary Portland cement because it demonstrated superior environmental advantages due to its lower carbon emissions and waste material utilization. This paper focuses on the formulation of geopolymer cement from nickel–laterite mine waste (NMW) and coal fly ash (CFA) as geopolymer precursors, and sodium hydroxide (SH), and sodium silicate (SS) as alkali activators. Different mix formulations of raw materials are prepared to produce a geopolymer based on an I-optimal design and obtained different compressive strengths. A mixed formulation of 50% NMW and 50% CFA, SH-to-SS ratio of 0.5, and an activator-to-precursor ratio of 0.429 yielded the highest 28 d unconfined compressive strength (UCS) of 22.10 ± 5.40 MPa. Furthermore, using an optimized formulation of 50.12% NMW, SH-to-SS ratio of 0.516, and an activator-to-precursor ratio of 0.428, a UCS value of 36.30 ± 3.60 MPa was obtained. The result implies that the synthesized geopolymer material can be potentially used for concrete structures and pavers, pedestrian pavers, light traffic pavers, and plain concrete. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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19 pages, 3772 KiB

Open AccessArticle

Co-Disposal of Coal Gangue and Red Mud for Prevention of Acid Mine Drainage Generation from Self-Heating Gangue Dumps

by Zhou Ran, Yongtai Pan and Wenli Liu

Minerals 2020, 10(12), 1081; https://doi.org/10.3390/min10121081 - 2 Dec 2020

Cited by 9 | Viewed by 2651

Abstract

The seepage and diffusion of acid mine drainage (AMD) generated from self-heating coal gangue tailings caused acid pollution to the surrounding soil and groundwater. Red mud derived from the alumina smelting process has a high alkali content. To explore the feasibility of co-disposal [...] Read more.

The seepage and diffusion of acid mine drainage (AMD) generated from self-heating coal gangue tailings caused acid pollution to the surrounding soil and groundwater. Red mud derived from the alumina smelting process has a high alkali content. To explore the feasibility of co-disposal of coal gangue and red mud for prevention of AMD, coal gangue and red mud were sampled from Yangquan (Shanxi Province, China), and dynamic leaching tests were carried out through the automatic temperature-controlled leaching system under the conditions of different temperatures, mass ratios, and storage methods. Our findings indicated that the heating temperature had a significant effect on the release characteristics of acidic pollutants derived from coal gangue, and that the fastest rate of acid production corresponding to temperature was 150 °C. The co-disposal dynamic leaching tests indicated that red mud not only significantly alleviated the release of AMD but also that it had a long-term effect on the treatment of acid pollution. The mass ratio and stacking method were selected to be 12:1 (coal gangue: red mud) and one layer was alternated (coal gangue covered with red mud), respectively, to ensure that the acid-base pollution indices of leachate reached the WHO drinking-water quality for long-term discharge. The results of this study provided a theoretical basis and data support for the industrial field application of solid waste co-treatment. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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20 pages, 25293 KiB

Open AccessArticle

The Use of Mining Waste Materials for the Treatment of Acid and Alkaline Mine Wastewater

by Jacek Retka, Grzegorz Rzepa, Tomasz Bajda and Lukasz Drewniak

Minerals 2020, 10(12), 1061; https://doi.org/10.3390/min10121061 - 27 Nov 2020

Cited by 19 | Viewed by 6771

Abstract

The mining of metal ores generates both liquid and solid wastes, which are increasingly important to manage. In this paper, an attempt was made to use waste rocks produced in the mining of zinc and lead to neutralizing acid mine drainage and alkaline [...] Read more.

The mining of metal ores generates both liquid and solid wastes, which are increasingly important to manage. In this paper, an attempt was made to use waste rocks produced in the mining of zinc and lead to neutralizing acid mine drainage and alkaline flotation wastewater. Waste rock is a quartz-feldspar rock of hydrothermal origin. It is composed of, besides quartz and potassium feldspar (orthoclase), phyllosilicates (chlorite and mica), and sulfides (chiefly pyrite). To determine its physicochemical parameters and their variability, acid mine water and flotation wastewater were monitored for 12 months. Acid mine drainage (AMD) is characterized by a low pH (~3), high zinc concentration (~750 mg·L⁻¹), and high sulfate content (~6800 mg·L⁻¹). On the other hand, the determinations made for flotation wastewater showed, among others, a pH of approximately 12 and ca. 780 mg·L⁻¹ of sulfates. AMD and flotation wastewater neutralization by the waste rock was shown to be possible and efficient. However, in both cases, the final solution contained elevated concentrations of metals and sulfates. Premixing AMD with alkaline flotation wastewater in the first step and then neutralizing the obtained mixture with the waste rock was considered the best solution. The produced solution had a circumneutral pH. However, the obtained solution does not meet the legislative requirements but could be further treated by, for example, passive treatment systems. It is noteworthy that the proposed approach is low cost and does not require any chemical reagents. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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11 pages, 1217 KiB

Open AccessArticle

Assessment of Native and Endemic Chilean Plants for Removal of Cu, Mo and Pb from Mine Tailings

by Pamela Lazo and Andrea Lazo

Minerals 2020, 10(11), 1020; https://doi.org/10.3390/min10111020 - 17 Nov 2020

Cited by 8 | Viewed by 3064

Abstract

In Chile, 85% of tailings impoundments are inactive or abandoned and many of them do not have a program of treatment or afforestation. The phytoremediation of tailings with Oxalis gigantea, Cistanthe grandiflora, Puya berteroniana and Solidago chilensis have been tested in [...] Read more.

In Chile, 85% of tailings impoundments are inactive or abandoned and many of them do not have a program of treatment or afforestation. The phytoremediation of tailings with Oxalis gigantea, Cistanthe grandiflora, Puya berteroniana and Solidago chilensis have been tested in order to find plants with ornamental value and low water requirements, which enable reductions in molybdenum (Mo), copper (Cu) or lead (Pb) concentrations creating an environmentally friendly surrounding. Ex-situ phytoremediation experiments were carried out for seven months and Mo, Cu and Pb were measured at the beginning and at the end of the growth period. The capacity of these species to phyto-remedy was evaluated using the bioconcentration and translocation factors, along with assessing removal efficiency. Solidago chilensis showed the ability to phytoextract Mo while Puya berteroniana showed potential for Cu and Mo stabilization. The highest removal efficiencies were obtained for Mo, followed by Cu and Pb. The maximum values of removal efficiency for Mo, Cu and Pb were 28.7% with Solidago chilensis, 15.6% with Puya berteroniana and 8.8% with Cistanthe grandiflora, respectively. Therefore, the most noticeable results were obtained with Solidago chilensis for phytoextraction of Mo. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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18 pages, 2198 KiB

Open AccessArticle

A Methodology Based on Magnetic Susceptibility to Characterize Copper Mine Tailings

by Elizabeth J. Lam, Rodrigo Carle, Rodrigo González, Ítalo L. Montofré, Eugenio A. Veloso, Antonio Bernardo, Manuel Cánovas and Fernando A. Álvarez

Minerals 2020, 10(11), 939; https://doi.org/10.3390/min10110939 - 22 Oct 2020

Cited by 5 | Viewed by 3486

Abstract

This paper intends to validate the application of magnetic techniques, particularly magnetic susceptibility, as sampling tools on a copper tailings terrace, by correlating them analytically. Magnetic susceptibility was measured in both the field and laboratory. Data obtained allowed for designing spatial magnetic susceptibility [...] Read more.

This paper intends to validate the application of magnetic techniques, particularly magnetic susceptibility, as sampling tools on a copper tailings terrace, by correlating them analytically. Magnetic susceptibility was measured in both the field and laboratory. Data obtained allowed for designing spatial magnetic susceptibility distribution maps, showing the horizontal variation of the tailings. In addition, boxplots were used to show the variation of magnetic susceptibility and the concentration of the elements analyzed at different depths of the copper tailings terrace. The degree of correlation between magnetic and chemical variables was defined with coefficient R2. The horizontal and vertical variations of magnetic susceptibility, the concentration of elements, and the significant correlations between them show a relationship between magnetic susceptibility and the chemical processes occurring in the tailing management facility, such as pyrite oxidation. Thus, the correlation functions obtained could be used as semiquantitative tools to characterize tailings or other mining residues. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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22 pages, 4350 KiB

Open AccessArticle

Chemical Treatment of Highly Toxic Acid Mine Drainage at A Gold Mining Site in Southwestern Siberia, Russia

by Svetlana Bortnikova, Olga Gaskova, Nataliya Yurkevich, Olga Saeva and Natalya Abrosimova

Minerals 2020, 10(10), 867; https://doi.org/10.3390/min10100867 - 30 Sep 2020

Cited by 21 | Viewed by 3400

Abstract

The critical environmental situation in the region of southwestern Siberia (Komsomolsk settlement, Kemerovo region) is the result of the intentional displacement of mine tailings with high sulfide concentrations. During storage, ponds of acidic water with incredibly high arsenic (up to 4 g/L) and [...] Read more.

The critical environmental situation in the region of southwestern Siberia (Komsomolsk settlement, Kemerovo region) is the result of the intentional displacement of mine tailings with high sulfide concentrations. During storage, ponds of acidic water with incredibly high arsenic (up to 4 g/L) and metals formed on the tailings. The application of chemical methods to treat these extremely toxic waters is implemented: milk of lime Ca(OH)₂, sodium sulfide Na₂S, and sodium hydroxide NaOH. Field experiments were carried out by sequential adding pre-weighed reagents to the solutions with control of the physicochemical parameters and element concentrations for each solution/reagent ratio. In the experiment with Ca(OH)₂, the pH increased to neutral values most slowly, which is contrary to the results from the experiment with NaOH. When neutralizing solutions with NaOH, arsenic-containing phases are formed most actively, arsenate chalcophyllite Cu₁₈Al₂(AsO₄)₄(SO₄)₃(OH)₂₄·36H₂O, a hydrated iron arsenate scorodite, kaatialaite FeAs₃O₉·8H₂O and Mg(H₂AsO₄)₂. A common specificity of the neutralization processes is the rapid precipitation of Fe hydroxides and gypsum, then the reverse release of pollutants under alkaline conditions. The chemistry of the processes is described using thermodynamic modeling. The main species of arsenic in the solutions are iron-arsenate complexes; at the end of the experiments with Ca(OH)₂, Na₂S, and NaOH, the main species of arsenic is CaAsO₄⁻, the most toxic acid H₃AsO₃ and AsO₄³⁻, respectively. It is recommended that full-scale experiments should use NaOH in the first stages and then Ca(OH)₂ for the subsequent neutralization. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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11 pages, 3399 KiB

Open AccessArticle

Effects of Ferrous Sulfate Addition on the Selective Flotation of Scheelite over Calcite and Fluorite

by Moon Young Jung, Jay Hyun Park and Kyoungkeun Yoo

Minerals 2020, 10(10), 864; https://doi.org/10.3390/min10100864 - 30 Sep 2020

Cited by 5 | Viewed by 2415

Abstract

The addition of ferrous sulfate as a depressant for Ca-bearing minerals such as calcite and fluorite during scheelite flotation was investigated to recover scheelite from tungsten mine tailings, using Hallimond-tube flotation tests, zeta-potential measurement and Fourier-transform infrared (FT-IR) analyses. The flotation tests indicate [...] Read more.

The addition of ferrous sulfate as a depressant for Ca-bearing minerals such as calcite and fluorite during scheelite flotation was investigated to recover scheelite from tungsten mine tailings, using Hallimond-tube flotation tests, zeta-potential measurement and Fourier-transform infrared (FT-IR) analyses. The flotation tests indicate that the selectivity of scheelite recovery was the largest over calcite and fluorite under the following conditions: 0.5 g sample, 50 g/ton AF65, 1 × 10⁻³ M sodium oleate, 1200 g/ton SF2 (sodium silicate and ferrous sulfate) depressant with the 8:2 ratio of sodium silicate and ferrous sulfate, 50 mL/min air injection rate, 5 min flotation time, and pH 8. The selectivity of scheelite flotation increased when the amount of SF2 depressant addition increased to 1200 g/ton, but it decreased by adding 1400 g/ton SF2, which would result from the precipitation of iron components. In the zeta potential results, the zeta potentials of scheelite with the collector show similar results regardless of the addition of SF2, while the change of zeta potentials of calcite and fluorite by adding NaO collector diminished when SF2 was added. In FT-IR analyses, the spectrum of NaO in scheelite results was observed regardless of the addition of SF2, while the spectra of NaO in calcite and fluorite results disappeared when SF2 was added. These results suggest that the addition of SF2 prevents the adsorption of NaO on the surface of calcite and fluorite. Therefore, the addition of SF2 could enhance the selectivity of scheelite flotation over calcite and fluorite. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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15 pages, 1990 KiB

Open AccessArticle

Evaluation of Efficiencies of Locally Available Neutralizing Agents for Passive Treatment of Acid Mine Drainage

by Casey Oliver A. Turingan, Giulio B. Singson, Bernadette T. Melchor, Richard D. Alorro, Arnel B. Beltran and Aileen H. Orbecido

Minerals 2020, 10(10), 845; https://doi.org/10.3390/min10100845 - 24 Sep 2020

Cited by 10 | Viewed by 4141

Abstract

Acid mine drainage (AMD) generated from the mining industry elevates environmental concerns due to the pollution and contamination it causes to bodies of water. Over the years, passive treatment of AMD using alkalinity-generating materials have been widely studied with pH neutralization as its [...] Read more.

Acid mine drainage (AMD) generated from the mining industry elevates environmental concerns due to the pollution and contamination it causes to bodies of water. Over the years, passive treatment of AMD using alkalinity-generating materials have been widely studied with pH neutralization as its commonly observed mechanism. During the treatment process, heavy metal removal is also promoted by precipitation due to pH change or through adsorption facilitated by the mineral component of the materials. In this study, four materials were used and investigated: (1) a low grade ore (LGO) made up of goethite, calcium oxide, and manganese aluminum oxide (2–3) limestone and concrete aggregates (CA) composed of calcite, and (4) fly ash consisting of quartz, hematite, and magnetite. The performance of each alkalinity-generating agent at varying AMD/media ratios was based on the change in pH, total dissolved solids (TDS), oxidation reduction potential (E_H); and heavy metals (Fe, Ni, and Al) removal and sulfate concentration reduction. Concrete aggregate displayed the most significant effect in treating AMD after raising the pH to 12.42 and removing 99% Fe, 99% Ni, 96% Al, and 57% sulfates. Afterwards, the efficiency of CA at various particle sizes were evaluated over 1 h. The smallest range at 2.00–3.35mm was observed to be most effective after 60 min, raising the pH to 6.78 and reducing 94% Fe, 78% Ni, and 92% Al, but only 28% sulfates. Larger particles of CA were able to remove higher amounts of sulfate up to 57%, similar to the jar test. Overall, CA is an effective treatment media for neutralization; however, its performance can be complemented by a second media for heavy metal and sulfate removal. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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12 pages, 4056 KiB

Open AccessArticle

Characterization of Slag Reprocessing Tailings-Based Geopolymers in Marine Environment

by Jie Wu, Jing Li, Feng Rao and Wanzhong Yin

Minerals 2020, 10(9), 832; https://doi.org/10.3390/min10090832 - 22 Sep 2020

Cited by 8 | Viewed by 2704

Abstract

In this study, copper slag reprocessing tailings (CSRT) were synthesized into geopolymers with 40%, 50% and 60% metakaolin. The evolution of compressive strength and microstructures of CSRT-based geopolymers in a marine environment was investigated. Except for compressive strength measurement, the characterizations of X-ray [...] Read more.

In this study, copper slag reprocessing tailings (CSRT) were synthesized into geopolymers with 40%, 50% and 60% metakaolin. The evolution of compressive strength and microstructures of CSRT-based geopolymers in a marine environment was investigated. Except for compressive strength measurement, the characterizations of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) were included. It was found that marine conditions changed the Si/Al ratio in the sodium-aluminosilicate-hydrate (N-A-S-H) gel backbone, promoted the geopolymerization process, led to more Q⁴(3Al), Q⁴(2Al) and Q⁴(1Al) gel formation and a higher compressive strength of the geopolymers. This provided a basis for the preparation of CSRT-based geopolymers into marine concrete. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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13 pages, 3293 KiB

Open AccessArticle

Effects of Backfilling Excavated Underground Space on Reducing Acid Mine Drainage in an Abandoned Mine

by Kohei Yamaguchi, Shingo Tomiyama, Toshifumi Igarashi, Saburo Yamagata, Masanori Ebato and Masatoshi Sakoda

Minerals 2020, 10(9), 777; https://doi.org/10.3390/min10090777 - 31 Aug 2020

Cited by 9 | Viewed by 2960

Abstract

Three-dimensional groundwater flow around an abandoned mine was simulated to evaluate the effects of backfilling the excavated underground space of the mine on reducing the acid mine drainage (AMD). The conceptual model of the groundwater flow consists of not only variable geological formations [...] Read more.

Three-dimensional groundwater flow around an abandoned mine was simulated to evaluate the effects of backfilling the excavated underground space of the mine on reducing the acid mine drainage (AMD). The conceptual model of the groundwater flow consists of not only variable geological formations but also vertical shafts, horizontal drifts, and the other excavated underground space. The steady-state groundwater flow in both days with high and little rainfall was calculated to calibrate the model. The calculated groundwater levels and flow rate of the AMD agreed with the measured ones by calibrating the hydraulic conductivity of the host rock, which was sensitive to groundwater flow in the mine. This validated model was applied to predict the flow rate of the AMD when backfilling the excavated underground space. The results showed that the flow rate of the AMD decreased by 5% to 30%. This indicates that backfilling the excavated space is one of the effective methods to reduce AMD of abandoned mines. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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16 pages, 3014 KiB

Open AccessArticle

Immobilization of Lead and Zinc Leached from Mining Residual Materials in Kabwe, Zambia: Possibility of Chemical Immobilization by Dolomite, Calcined Dolomite, and Magnesium Oxide

by Pawit Tangviroon, Kenta Noto, Toshifumi Igarashi, Takeshi Kawashima, Mayumi Ito, Tsutomu Sato, Walubita Mufalo, Meki Chirwa, Imasiku Nyambe, Hokuto Nakata, Shouta Nakayama and Mayumi Ishizuka

Minerals 2020, 10(9), 763; https://doi.org/10.3390/min10090763 - 28 Aug 2020

Cited by 26 | Viewed by 4357

Abstract

Massive amount of highly contaminated mining residual materials (MRM) has been left unattended and has leached heavy metals, particularly lead (Pb) and zinc (Zn) to the surrounding environments. Thus, the performance of three immobilizers, raw dolomite (RD), calcined dolomite (CD), and magnesium oxide [...] Read more.

Massive amount of highly contaminated mining residual materials (MRM) has been left unattended and has leached heavy metals, particularly lead (Pb) and zinc (Zn) to the surrounding environments. Thus, the performance of three immobilizers, raw dolomite (RD), calcined dolomite (CD), and magnesium oxide (MO), was evaluated using batch experiments to determine their ability to immobilize Pb and Zn, leached from MRM. The addition of immobilizers increased the leachate pH and decreased the amounts of dissolved Pb and Zn to different extents. The performance of immobilizers to immobilize Pb and Zn followed the following trend: MO > CD > RD. pH played an important role in immobilizing Pb and Zn. Dolomite in RD could slightly raise the pH of the MRM leachate. Therefore, the addition of RD immobilized Pb and Zn via adsorption and co-precipitation, and up to 10% of RD addition did not reduce the concentrations of Pb and Zn to be lower than the effluent standards in Zambia. In contrast, the presence of magnesia in CD and MO significantly contributed to the rise of leachate pH to the value where it was sufficient to precipitate hydroxides of Pb and Zn and decrease their leaching concentrations below the regulated values. Even though MO outperformed CD, by considering the local availability of RD to produce CD, CD could be a potential immobilizer to be implemented in Zambia. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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21 pages, 6192 KiB

Open AccessArticle

Effectiveness of Fly Ash and Red Mud as Strategies for Sustainable Acid Mine Drainage Management

by Viktoria Keller, Srećko Stopić, Buhle Xakalashe, Yiqian Ma, Sehliselo Ndlovu, Brian Mwewa, Geoffrey S. Simate and Bernd Friedrich

Minerals 2020, 10(8), 707; https://doi.org/10.3390/min10080707 - 10 Aug 2020

Cited by 18 | Viewed by 4007

Abstract

Acid mine drainage (AMD), red mud (RM) and coal fly ash (CFA) are potential high environmental pollution problems due to their acidity, toxic metals and sulphate contents. Treatment of acidic mine water requires the generation of enough alkalinity to neutralize the excess acidity. [...] Read more.

Acid mine drainage (AMD), red mud (RM) and coal fly ash (CFA) are potential high environmental pollution problems due to their acidity, toxic metals and sulphate contents. Treatment of acidic mine water requires the generation of enough alkalinity to neutralize the excess acidity. Therefore, red mud types from Germany and Greece were chosen for the neutralization of AMD from South Africa, where this problem is notorious. Because of the high alkalinity, German red mud is the most promising precipitation agent achieving the highest pH-values. CFA is less efficient for a neutralization and precipitation process. An increase in temperature increases the adsorption kinetics. The maximum pH-value of 6.0 can be reached by the addition of 100 g German red mud at 20 °C to AMD-water with an initial pH value of 1.9. German red mud removes 99% of the aluminium as aluminium hydroxide at pH 5.0. The rare earth elements (yttrium and cerium) are adsorbed by Greek red mud with an efficiency of 50% and 80% at 60 °C in 5 min, respectively. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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16 pages, 4914 KiB

Open AccessEditor’s ChoiceArticle

Effective Treatment of Acid Mine Drainage with Microbial Fuel Cells: An Emphasis on Typical Energy Substrates

by Chenbing Ai, Zhang Yan, Shanshan Hou, Xiaoya Zheng, Zichao Zeng, Charles Amanze, Zhimin Dai, Liyuan Chai, Guanzhou Qiu and Weimin Zeng

Minerals 2020, 10(5), 443; https://doi.org/10.3390/min10050443 - 15 May 2020

Cited by 32 | Viewed by 7430

Abstract

Acid mine drainage (AMD), characterized by a high concentration of heavy metals, poses a threat to the ecosystem and human health. Bioelectrochemical system (BES) is a promising technology for the simultaneous treatment of organic wastewater and recovery of metal ions from AMD. Different [...] Read more.

Acid mine drainage (AMD), characterized by a high concentration of heavy metals, poses a threat to the ecosystem and human health. Bioelectrochemical system (BES) is a promising technology for the simultaneous treatment of organic wastewater and recovery of metal ions from AMD. Different kinds of organic wastewater usually contain different predominant organic chemicals. However, the effect of different energy substrates on AMD treatment and microbial communities of BES remains largely unknown. Here, results showed that different energy substrates (such as glucose, acetate, ethanol, or lactate) affected the startup, maximum voltage output, power density, coulombic efficiency, and microbial communities of the microbial fuel cell (MFC). Compared with the maximum voltage output (55 mV) obtained by glucose-fed-MFC, much higher maximum voltage output (187 to 212 mV) was achieved by MFCs fed individually with other energy substrates. Acetate-fed-MFC showed the highest power density (195.07 mW/m²), followed by lactate (98.63 mW/m²), ethanol (52.02 mW/m²), and glucose (3.23 mW/m²). Microbial community analysis indicated that the microbial communities of anodic electroactive biofilms changed with different energy substrates. The unclassified_f_Enterobacteriaceae (87.48%) was predominant in glucose-fed-MFC, while Geobacter species only accounted for 0.63%. The genera of Methanobrevibacter (23.70%), Burkholderia-Paraburkholderia (23.47%), and Geobacter (11.90%) were the major genera enriched in the ethanol-fed-MFC. Geobacter was most predominant in MFC enriched by lactate (45.28%) or acetate (49.72%). Results showed that the abundance of exoelectrogens Geobacter species correlated to electricity-generation capacities of electroactive biofilms. Electroactive biofilms enriched with acetate, lactate, or ethanol effectively recovered all Cu²⁺ ion (349 mg/L) of simulated AMD in a cathodic chamber within 53 h by reduction as Cu⁰ on the cathode. However, only 34.65% of the total Cu²⁺ ion was removed in glucose-fed-MFC by precipitation with anions and cations rather than Cu⁰ on the cathode. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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14 pages, 2188 KiB

Open AccessArticle

Forecast of AMD Quantity by a Series Tank Model in Three Stages: Case Studies in Two Closed Japanese Mines

by Chiharu Tokoro, Kenichiro Fukaki, Masakazu Kadokura and Shigeshi Fuchida

Minerals 2020, 10(5), 430; https://doi.org/10.3390/min10050430 - 11 May 2020

Cited by 10 | Viewed by 2788

Abstract

There are about 100 sites of acid mine drainage (AMD) from abandoned/closed mines in Japan. For their sustainable treatment, future prediction of AMD quantity is crucial. In this study, AMD quantity was predicted for two closed mines in Japan based on a series [...] Read more.

There are about 100 sites of acid mine drainage (AMD) from abandoned/closed mines in Japan. For their sustainable treatment, future prediction of AMD quantity is crucial. In this study, AMD quantity was predicted for two closed mines in Japan based on a series tank model in three stages. The tank model parameters were determined from the relationship between the observed AMD quantity and the inflow of rainfall and snowmelt by using the Kalman filter and particle swarm optimization methods. The Automated Meteorological Data Acquisition System (AMeDAS) data of rainfall were corrected for elevation and by the statistical daily fluctuation model. The snowmelt was estimated from the AMeDAS data of rainfall, temperature, and sunshine duration by using mass and heat balance of snow. Fitting with one year of daily data was sufficient to obtain the AMD quantity model. Future AMD quantity was predicted by the constructed model using the forecast data of rainfall and temperature proposed by the Max Planck Institute–Earth System Model (MPI–ESM), based on the Intergovernmental Panel on Climate Change (IPCC) representative concentration pathway (RCP) 2.6 and RCP8.5 scenarios. The results showed that global warming causes an increase in the quantity and fluctuation of AMD, especially for large reservoirs and residence time of AMD. There is a concern that for mines with large AMD quantities, AMD treatment will be unstable due to future global warming. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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Review

Jump to: Editorial, Research

38 pages, 1516 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Mine Waste Rock: Insights for Sustainable Hydrogeochemical Management

by Bas Vriens, Benoît Plante, Nicolas Seigneur and Heather Jamieson

Minerals 2020, 10(9), 728; https://doi.org/10.3390/min10090728 - 19 Aug 2020

Cited by 69 | Viewed by 15229

Abstract

Mismanagement of mine waste rock can mobilize acidity, metal (loid)s, and other contaminants, and thereby negatively affect downstream environments. Hence, strategic long-term planning is required to prevent and mitigate deleterious environmental impacts. Technical frameworks to support waste-rock management have existed for decades and [...] Read more.

Mismanagement of mine waste rock can mobilize acidity, metal (loid)s, and other contaminants, and thereby negatively affect downstream environments. Hence, strategic long-term planning is required to prevent and mitigate deleterious environmental impacts. Technical frameworks to support waste-rock management have existed for decades and typically combine static and kinetic testing, field-scale experiments, and sometimes reactive-transport models. Yet, the design and implementation of robust long-term solutions remains challenging to date, due to site-specificity in the generated waste rock and local weathering conditions, physicochemical heterogeneity in large-scale systems, and the intricate coupling between chemical kinetics and mass- and heat-transfer processes. This work reviews recent advances in our understanding of the hydrogeochemical behavior of mine waste rock, including improved laboratory testing procedures, innovative analytical techniques, multi-scale field investigations, and reactive-transport modeling. Remaining knowledge-gaps pertaining to the processes involved in mine waste weathering and their parameterization are identified. Practical and sustainable waste-rock management decisions can to a large extent be informed by evidence-based simplification of complex waste-rock systems and through targeted quantification of a limited number of physicochemical parameters. Future research on the key (bio)geochemical processes and transport dynamics in waste-rock piles is essential to further optimize management and minimize potential negative environmental impacts. Full article

(This article belongs to the Special Issue Novel and Emerging Strategies for Sustainable Mine Tailings and Acid Mine Drainage Management)

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