Special Issue "Mine Waste Characterization, Management and Remediation"

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A special issue of Minerals (ISSN 2075-163X).

Deadline for manuscript submissions: closed (31 December 2013)

Special Issue Editors

Guest Editor
Prof. Dr. Karen Hudson-Edwards (Website)

Department of Earth and Planetary Sciences Birkbeck, University of London London WC1E 7HX UK
Interests: mine waste characterization; management and remediation; environmental mineralogy; mineral-microbe interactions; mineral dissolution; sulfate minerals; biogeochemical cycles; economic geology
Guest Editor
Prof. Dr. Bernhard Dold (Website)

SUMIRCO (Sustainable Mining Research & Consult EIRL), Casilla 28, San Pedro de la Paz 4130000, Chile
Interests: economic geology; mineralogy; geochemistry; geomicrobiology; biogeochemical cycles; biogeometallurgy; mine waste management; mine waste characterization and prediction; sustainability; hydrogeology; sustainable georesources management

Special Issue Information

Dear Colleagues,

Mining is a vital part of the Global economy, but the extraction of metals, metalloids and other mineral products generates vast quantities of liquid and solid wastes. These wastes can pose risks to ecosystems and humans because they can contain high concentrations of potentially toxic elements. These risks can be mitigated by implementing appropriate management or remediation schemes. Although there are a large number of such schemes available, there is still a need to research the processes, products and effectiveness of their implementation, as well as the nature of the mine wastes themselves. This special issue aims to bring together studies in the areas of mine waste characterization, management and remediation, to review the current state of knowledge and to develop improvements in current schemes. We welcome studies in all of these areas, including schemes involving bacteria and phytoremediation.

Dr. Karen Hudson-Edwards
Prof. Dr. Bernhard Dold
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. For this special issue, the Article Processing Charge (APC) will be waived. English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • mine waste
  • acid mine drainage, neutral mine drainage, basic mine drainage
  • tailings, metallurgical slags and waste rock
  • bioremediation
  • phytoremediation
  • permeable reactive barriers
  • passive and active treatment schemes
  • mine waste management
  • prediction and prevention
  • characterization

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial Mine Waste Characterization, Management and Remediation
Minerals 2015, 5(1), 82-85; doi:10.3390/min5010082
Received: 28 October 2014 / Accepted: 6 January 2015 / Published: 19 January 2015
PDF Full-text (627 KB) | HTML Full-text | XML Full-text
Abstract
Mining is a vital part of the Global economy, but the extraction of metals, metalloids, and other mineral products generates vast quantities of liquid and solid waste. Currently the volume is estimated at several thousand million tons per annum, but is [...] Read more.
Mining is a vital part of the Global economy, but the extraction of metals, metalloids, and other mineral products generates vast quantities of liquid and solid waste. Currently the volume is estimated at several thousand million tons per annum, but is increasing exponentially as demand and exploitation of lower-grade deposits increases. The high concentrations of potentially toxic elements in these wastes can pose risks to ecosystems and humans, but these risks can be mitigated by implementing appropriate management or remediation schemes. Although there are a large number of such schemes available, there is still a need to research the processes, products, and effectiveness of implementation, as well as the nature of the mine wastes themselves. This Special Issue is aimed at bringing together studies in the areas of mine waste characterization, management, and remediation, to review the current state of knowledge and to develop improvements in current schemes. Fourteen manuscripts are published for this Special Issue, and these are summarized below.[...] Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)

Research

Jump to: Editorial, Review

Open AccessArticle Evolution of Geochemical and Mineralogical Parameters during In Situ Remediation of a Marine Shore Tailings Deposit by the Implementation of a Wetland Cover
Minerals 2014, 4(3), 578-602; doi:10.3390/min4030578
Received: 27 February 2014 / Revised: 23 June 2014 / Accepted: 24 June 2014 / Published: 8 July 2014
Cited by 4 | PDF Full-text (7382 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We present data of the time-evolution of a remediation approach on a marine shore tailings deposit by the implementation of an artificial wetland. Two remediation cells were constructed: one in the northern area at sea-level and one in the central delta area [...] Read more.
We present data of the time-evolution of a remediation approach on a marine shore tailings deposit by the implementation of an artificial wetland. Two remediation cells were constructed: one in the northern area at sea-level and one in the central delta area (above sea-level) of the tailings. At the beginning, the “sea-level” remediation cell had a low pH (3.1), with high concentrations of dissolved metals and sulfate and chloride ions and showed sandy grain size. After wetland implementation, the “sea-level” remediation cell was rapidly water-saturated, the acidity was consumed, and after four months the efficiency of metal removal from solution was up to 79.5%–99.4% for Fe, 94.6%–99.9% for Mn, and 96.1%–99.6% for Zn. Al and Cu concentrations decreased below detection limit. The “above sea-level” remediation cell was characterized by the same pH (3.1) and finer grain size (clayey–silty), and with some lower element concentrations than in the “sea-level” cell. Even after one year of flooding, the “above sea-level” cell was not completely flooded, showing on-going sulfide oxidation in between the wetland cover and the groundwater level; the pH increased only to 4.4 and metal concentrations decreased only by 96% for Fe, 88% for Al, 51% for Cu, 97% for Mn, and 95% for Zn. During a dry period, the water level dropped in the “sea-level” cell, resulting in a seawater ingression, which triggered the desorption of As into solution. These data show that the applied remediation approach for this tailings deposit is successful, if the system is maintained water-saturated. Metal removal from solution was possible in both systems: first, as a result of sorption on Fe(III) hydroxide/and/or clay minerals and/or co-precipitation processes after rise of pH; and then, with more reducing conditions, due to metal sulfides precipitation. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater
Minerals 2014, 4(3), 603-620; doi:10.3390/min4030603
Received: 10 March 2014 / Revised: 17 June 2014 / Accepted: 18 June 2014 / Published: 8 July 2014
Cited by 3 | PDF Full-text (1567 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, [...] Read more.
Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, and goethite in sea water (common secondary minerals in coastal tailings) was investigated. The aim of the investigation was to establish As retention and transport under a marine flood scenario, which may occur due to climate change. Natural and synthetic minerals with co-precipitated and adsorbed As were contacted with seawater for 25 days. During this period As, Fe, Cl, SO4, and pH levels were constantly measured. The larger retention capability of samples with co-precipitated As, in relation with adsorbed As samples, reflects the different kinetics between diffusion, dissolution, and surface exchange processes. Ferrihydrite and schwertmannite showed good results in retaining arsenic, although schwertmannite holding capacity was enhanced due its buffering capacity, which prevented reductive dissolution throughout the experiment. Arsenic desorption from goethite could be understood in terms of ion exchange between oxides and electrolytes, due to the charge difference generated by a low point-of-zero-charge and the change in stability of surface complexes between synthesis conditions and natural media. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Jarosite versus Soluble Iron-Sulfate Formation and Their Role in Acid Mine Drainage Formation at the Pan de Azúcar Mine Tailings (Zn-Pb-Ag), NW Argentina
Minerals 2014, 4(2), 477-502; doi:10.3390/min4020477
Received: 28 February 2014 / Revised: 12 May 2014 / Accepted: 19 May 2014 / Published: 30 May 2014
Cited by 7 | PDF Full-text (7430 KB) | HTML Full-text | XML Full-text
Abstract
Secondary jarosite and water-soluble iron-sulfate minerals control the composition of acid mine waters formed by the oxidation of sulfide in tailings impoundments at the (Zn-Pb-Ag) Pan de Azúcar mine located in the Pozuelos Lagoon Basin (semi-arid climate) in Northwest (NW) Argentina. In [...] Read more.
Secondary jarosite and water-soluble iron-sulfate minerals control the composition of acid mine waters formed by the oxidation of sulfide in tailings impoundments at the (Zn-Pb-Ag) Pan de Azúcar mine located in the Pozuelos Lagoon Basin (semi-arid climate) in Northwest (NW) Argentina. In the primary zone of the tailings (9.5 wt % pyrite-marcasite) precipitation of anglesite (PbSO4), wupatkite ((Co,Mg,Ni)Al2(SO4)4) and gypsum retain Pb, Co and Ca, while mainly Fe2+, Zn2+, Al3+, Mg2+, As3+/5+ and Cd2+ migrate downwards, forming a sulfate and metal-rich plume. In the oxidation zone, jarosite (MFe3(TO4)2(OH)6) is the main secondary Fe3+ phase; its most suitable composition is M = K+, Na+, and Pb2+and TO4 = SO42−; AsO42−. During the dry season, iron-sulfate salts precipitate by capillary transport on the tailings and at the foot of DC2 (tailings impoundment DC2) tailings dam where an acid, Fe2+ rich plume outcrops. The most abundant compounds in the acid mine drainage (AMD) are SO42−, Fe2+, Fe3+, Zn2+, Al3+, Mg2+, Cu2+, As3+/5+, Cd2+. These show peak concentrations at the beginning of the wet season, when the soluble salts and jarosite dissolve. The formation of soluble sulfate salts during the dry season and dilution during the wet season conform an annual cycle of rapid metals and acidity transference from the tailings to the downstream environment. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Characterization of Green Liquor Dregs, Potentially Useful for Prevention of the Formation of Acid Rock Drainage
Minerals 2014, 4(2), 330-344; doi:10.3390/min4020330
Received: 26 February 2014 / Revised: 14 April 2014 / Accepted: 14 April 2014 / Published: 22 April 2014
Cited by 6 | PDF Full-text (1143 KB) | HTML Full-text | XML Full-text
Abstract
Using alternative materials such as residual products from other industries to mitigate the negative effects of acid rock drainage would simultaneously solve two environmental problems. The main residual product still landfilled by sulphate paper mills is the alkaline material green liquor dregs [...] Read more.
Using alternative materials such as residual products from other industries to mitigate the negative effects of acid rock drainage would simultaneously solve two environmental problems. The main residual product still landfilled by sulphate paper mills is the alkaline material green liquor dregs (GLD). A physical, mineralogical and chemical characterization of four batches of GLD was carried out to evaluate the potential to use it as a sealing layer in the construction of dry covers on sulphide-bearing mine waste. GLD has relatively low hydraulic conductivity (10−8 to 10−9 m/s), a high water retention capacity (WRC) and small particle size. Whilst the chemical and mineralogical composition varied between the different batches, these variations were not reflected in properties such as hydraulic conductivity and WRC. Due to relatively low trace element concentrations, leaching of contaminants from the GLD is not a concern for the environment. However, GLD is a sticky material, difficult to apply on mine waste deposits and the shear strength is insufficient for engineering applications. Therefore, improving the mechanical properties is necessary. In addition, GLD has a high buffering capacity indicating that it could act as an alkaline barrier. Once engineering technicalities have been overcome, the long-term effectiveness of GLD should be studied, especially the effect of aging and how the sealing layer would be engineered in respect to topography and climatic conditions. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Mapping Changes in a Recovering Mine Site with Hyperspectral Airborne HyMap Imagery (Sotiel, SW Spain)
Minerals 2014, 4(2), 313-329; doi:10.3390/min4020313
Received: 31 October 2013 / Revised: 2 April 2014 / Accepted: 10 April 2014 / Published: 16 April 2014
Cited by 2 | PDF Full-text (5241 KB) | HTML Full-text | XML Full-text
Abstract
Hyperspectral high spatial resolution HyMap data are used to map mine waste from massive sulfide ore deposits, mostly abandoned, on the Iberian Pyrite Belt (southwest Spain). Mine dams, mill tailings and mine dumps in variable states of pyrite oxidation are recognizable. The [...] Read more.
Hyperspectral high spatial resolution HyMap data are used to map mine waste from massive sulfide ore deposits, mostly abandoned, on the Iberian Pyrite Belt (southwest Spain). Mine dams, mill tailings and mine dumps in variable states of pyrite oxidation are recognizable. The interpretation of hyperspectral remote sensing requires specific algorithms able to manage high dimensional data compared to multispectral data. The routine of image processing methods used to extract information from hyperspectral data to map geological features is explained, as well as the sequence of algorithms used to produce maps of the mine sites. The mineralogical identification capability of algorithms to produce maps based on archive spectral libraries is discussed. Trends of mineral growth differ spectrally over time according to the geological setting and the recovery state of the mine site. Subtle mineralogical changes are enhanced using the spectral response as indicators of pyrite oxidation intensity of the mine waste piles and pyrite mud tailings. The changes in the surface of the mill tailings deserve a detailed description, as the surfaces are inaccessible to direct observation. Such mineralogical changes respond faithfully to industrial activities or the influence of climate when undisturbed by human influence. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Long-Term Acid-Generating and Metal Leaching Potential of a Sub-Arctic Oil Shale
Minerals 2014, 4(2), 293-312; doi:10.3390/min4020293
Received: 19 February 2014 / Revised: 8 April 2014 / Accepted: 10 April 2014 / Published: 14 April 2014
Cited by 3 | PDF Full-text (835 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Shales are increasingly being exploited for oil and unconventional gas. Exploitation of sub-arctic oil shales requires the creation of gravel pads to elevate workings above the heaving effects of ground ice. These gravel pads can potentially generate acidic leachate, which can enhance [...] Read more.
Shales are increasingly being exploited for oil and unconventional gas. Exploitation of sub-arctic oil shales requires the creation of gravel pads to elevate workings above the heaving effects of ground ice. These gravel pads can potentially generate acidic leachate, which can enhance the mobility of metals from the shale. To examine this potential, pyrite-bearing shale originating from sub-Arctic gravel pad sites were subjected to leaching tests for 600 days at initial pH values ranging from 2 to 5, to simulate potential real world conditions. At set times over the 600 day experiment, pH, oxidation reduction potential (ORP), dissolved oxygen and temperature were recorded and small liquid samples withdrawn and analysed for elemental concentrations using total reflection X-ray fluorescence spectrometry (TRXRF). Six of eight shale samples were found to be acid generating, with pH declining and ORP becoming increasingly positive after 100 days. Two of the eight shale samples produced increasingly alkaline leachate conditions with relatively low ORP after 100 days, indicating an inbuilt buffering capacity. By 600 days the buffering capacity of all samples had been consumed and all leachate samples were acidic. TRXRF analyses demonstrated significant potential for the leaching of S, Fe, Ni, Cu, Zn and Mn with greatest concentrations found in reaction vessels with most acidic pH and highest ORP. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
Open AccessArticle Diavik Waste Rock Project: Evolution of Mineral Weathering, Element Release, and Acid Generation and Neutralization during a Five-Year Humidity Cell Experiment
Minerals 2014, 4(2), 257-278; doi:10.3390/min4020257
Received: 30 January 2014 / Revised: 29 March 2014 / Accepted: 1 April 2014 / Published: 10 April 2014
Cited by 6 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
A five-year, humidity-cell experiment was used to study the weathering evolution of a low-sulfide, granitic waste rock at 5 and 22 °C. Only the rock with the highest sulfide content (0.16 wt %) released sufficient acid to overcome a limited carbonate acid-neutralization [...] Read more.
A five-year, humidity-cell experiment was used to study the weathering evolution of a low-sulfide, granitic waste rock at 5 and 22 °C. Only the rock with the highest sulfide content (0.16 wt %) released sufficient acid to overcome a limited carbonate acid-neutralization capacity and produce a substantial decline in pH. Leached SO4 and Ca quickly increased then decreased during the first two years of weathering. Sulfide oxidation continued to release acid and SO4 after carbonate depletion, resulting in an increase in acid-soluble elements, including Cu and Zn. With the dissolution of Al-bearing minerals, the pH stabilized above 4, and sulfide oxidation continued to decline until the end of the experiment. The variation in activation energy of sulfide oxidation correlates with changes in sulfide availability, where the lowest activation energies occurred during the largest releases of SO4. A decrease in sulfide availability was attributed to consumption of sulfide and weathered rims on sulfide grains that reduced the oxidation rate. Varying element release rates due to changing carbonate and sulfide availability provide identifiable geochemical conditions that can be viewed as neutralization sequences and may be extrapolated to the field site for examining the evolution of mineral weathering of the waste rock. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
Open AccessArticle Effects of the November 2012 Flood Event on the Mobilization of Hg from the Mount Amiata Mining District to the Sediments of the Paglia River Basin
Minerals 2014, 4(2), 241-256; doi:10.3390/min4020241
Received: 28 February 2014 / Revised: 1 April 2014 / Accepted: 2 April 2014 / Published: 9 April 2014
Cited by 4 | PDF Full-text (13391 KB) | HTML Full-text | XML Full-text
Abstract
The Mount Amiata mining district (southern Tuscany, Italy) was, for decades, one of the world’s largest mercury (Hg) producing regions, where mining activity lasted until the 1980s. The Paglia River drains the eastern part of the district and is also the main [...] Read more.
The Mount Amiata mining district (southern Tuscany, Italy) was, for decades, one of the world’s largest mercury (Hg) producing regions, where mining activity lasted until the 1980s. The Paglia River drains the eastern part of the district and is also the main western tributary of the Tiber River. Recent studies show that, still today, high total Hg contents severely affect the downstream ecosystems of these rivers. In November 2012, a major flood event occurred in the Paglia River basin, which drastically changed the river morphology and, possibly, the Hg concentrations. In the present work, stream sediment was sampled before and after the flood to evaluate possible changes in sediment total Hg concentrations as a consequence of this event. The comparison between pre- and post-flood Hg concentrations shows that Hg content increased up to an order of magnitude after the flood, suggesting that this event triggered Hg mobilization in the basin rather than its dilution. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessArticle Thermal Treatment of Mercury Mine Wastes Using a Rotary Solar Kiln
Minerals 2014, 4(1), 37-51; doi:10.3390/min4010037
Received: 20 November 2013 / Revised: 24 January 2014 / Accepted: 24 January 2014 / Published: 28 January 2014
Cited by 5 | PDF Full-text (1833 KB) | HTML Full-text | XML Full-text
Abstract
Thermal desorption, by a rotary kiln of mercury contaminated soil and mine wastes, has been used in order to volatilize mercury from the contaminated medium. Solar thermal desorption is an innovative treatment that uses solar energy to increase the volatility of contaminants, [...] Read more.
Thermal desorption, by a rotary kiln of mercury contaminated soil and mine wastes, has been used in order to volatilize mercury from the contaminated medium. Solar thermal desorption is an innovative treatment that uses solar energy to increase the volatility of contaminants, which are removed from a solid matrix by a controlled air flow system. Samples of soils and mine wastes used in the experiments were collected in the abandoned Valle del Azogue mine (SE, Spain), where a complex ore, composed mainly of cinnabar, arsenic minerals (realgar and orpiment) and stibnite, was mined. The results showed that thermal treatment at temperatures >400 °C successfully lowered the Hg content (2070–116 ppm) to <15 mg kg−1. The lowest values of mercury in treated samples were obtained at a higher temperature and exposition time. The samples that showed a high removal efficiency (>99%) were associated with the presence of significant contents of cinnabar and an equivalent diameter above 0.8 mm. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
Open AccessArticle Primary Phases and Natural Weathering of Smelting Slag at an Abandoned Mine Site in Southwest Japan
Minerals 2013, 3(4), 412-426; doi:10.3390/min3040412
Received: 12 October 2013 / Revised: 26 November 2013 / Accepted: 28 November 2013 / Published: 13 December 2013
Cited by 5 | PDF Full-text (2906 KB) | HTML Full-text | XML Full-text
Abstract
Artisanal metallurgical slag produced more than 50 years ago at a mine site in southwest Japan is rich in toxic metals and metalloids. Some of the slag remains on a waste dump and could contaminate the surrounding area through the dissolution of [...] Read more.
Artisanal metallurgical slag produced more than 50 years ago at a mine site in southwest Japan is rich in toxic metals and metalloids. Some of the slag remains on a waste dump and could contaminate the surrounding area through the dissolution of heavy metals and metalloids during weathering. To assess this risk, this study has investigated the behavior of the toxic elements in the smelting slag during weathering. Most of the potentially toxic elements are contained in willemite and/or matte drops. Maximum metal and metalloid concentrations in the slag are 28.1 wt % Fe, 22.7 wt % Zn, 1.63 wt % Cu, 3450 mg/kg Sn, 826 mg/kg Pb, 780 mg/kg As, and 116 mg/kg Cd. Zn is mainly contained in willemite, whereas other metals and metalloids are mainly concentrated in matte drops. The willemite and matte drops are converted to Fe-hydroxides during weathering, indicating that potentially toxic metals and metalloids contained in these phases are released by weathering processes. Therefore, weathering of the artisanal metallurgical slag, containing large amounts of willemite and matte drops, may pollute the surrounding environment. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Review

Jump to: Editorial, Research

Open AccessReview Evolution of Acid Mine Drainage Formation in Sulphidic Mine Tailings
Minerals 2014, 4(3), 621-641; doi:10.3390/min4030621
Received: 26 February 2014 / Revised: 21 April 2014 / Accepted: 21 April 2014 / Published: 8 July 2014
Cited by 11 | PDF Full-text (1925 KB) | HTML Full-text | XML Full-text
Abstract
Sulphidic mine tailings are among the largest mining wastes on Earth and are prone to produce acid mine drainage (AMD). The formation of AMD is a sequence of complex biogeochemical and mineral dissolution processes. It can be classified in three main steps [...] Read more.
Sulphidic mine tailings are among the largest mining wastes on Earth and are prone to produce acid mine drainage (AMD). The formation of AMD is a sequence of complex biogeochemical and mineral dissolution processes. It can be classified in three main steps occurring from the operational phase of a tailings impoundment until the final appearance of AMD after operations ceased: (1) During the operational phase of a tailings impoundment the pH-Eh regime is normally alkaline to neutral and reducing (water-saturated). Associated environmental problems include the presence of high sulphate concentrations due to dissolution of gypsum-anhydrite, and/or effluents enriched in elements such as Mo and As, which desorbed from primary ferric hydroxides during the alkaline flotation process. (2) Once mining-related operations of the tailings impoundment has ceased, sulphide oxidation starts, resulting in the formation of an acidic oxidation zone and a ferrous iron-rich plume below the oxidation front, that re-oxidises once it surfaces, producing the first visible sign of AMD, i.e., the precipitation of ferrihydrite and concomitant acidification. (3) Consumption of the (reactive) neutralization potential of the gangue minerals and subsequent outflow of acidic, heavy metal-rich leachates from the tailings is the final step in the evolution of an AMD system. The formation of multi-colour efflorescent salts can be a visible sign of this stage. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessReview Submarine Tailings Disposal (STD)—A Review
Minerals 2014, 4(3), 642-666; doi:10.3390/min4030642
Received: 26 February 2014 / Revised: 24 May 2014 / Accepted: 9 June 2014 / Published: 8 July 2014
Cited by 8 | PDF Full-text (918 KB) | HTML Full-text | XML Full-text
Abstract
The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the [...] Read more.
The mining industry is a fundamental industry involved in the development of modern society, but is also the world’s largest waste producer. This role will be enhanced in the future, because ore grades are generally decreasing, thus leading to increases in the waste/metal production ratio. Mine wastes deposited on-land in so-called tailings dams, impoundments or waste-dumps have several associated environmental issues that need to be addressed (e.g., acid mine drainage formation due to sulphide oxidation, geotechnical stability, among others), and social concerns due to land use during mining. The mining industry recognizes these concerns and is searching for waste management alternatives for the future. One option used in the past was the marine shore or shallow submarine deposition of this waste material in some parts of the world. After the occurrence of some severe environmental pollution, today the deposition in the deep sea (under constant reducing conditions) is seen as a new, more secure option, due to the general thought that sulphide minerals are geochemically stable under the reduced conditions prevailing in the deep marine environment. This review highlights the mineralogical and geochemical issues (e.g., solubility of sulphides in seawater; reductive dissolution of oxide minerals under reducing conditions), which have to be considered when evaluating whether submarine tailings disposal is a suitable alternative for mine waste. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
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Open AccessReview Recent Developments in Microbiological Approaches for Securing Mine Wastes and for Recovering Metals from Mine Waters
Minerals 2014, 4(2), 279-292; doi:10.3390/min4020279
Received: 11 March 2014 / Revised: 3 April 2014 / Accepted: 10 April 2014 / Published: 14 April 2014
Cited by 11 | PDF Full-text (756 KB) | HTML Full-text | XML Full-text
Abstract
Mining of metals and coals generates solid and liquid wastes that are potentially hazardous to the environment. Traditional methods to reduce the production of pollutants from mining and to treat impacted water courses are mostly physico-chemical in nature, though passive remediation of [...] Read more.
Mining of metals and coals generates solid and liquid wastes that are potentially hazardous to the environment. Traditional methods to reduce the production of pollutants from mining and to treat impacted water courses are mostly physico-chemical in nature, though passive remediation of mine waters utilizes reactions that are catalysed by microorganisms. This paper reviews recent advances in biotechnologies that have been proposed both to secure reactive mine tailings and to remediate mine waters. Empirical management of tailings ponds to promote the growth of micro-algae that sustain populations of bacteria that essentially reverse the processes involved in the formation of acid mine drainage has been proposed. Elsewhere, targeted biomineralization has been demonstrated to produce solid products that allow metals present in mine waters to be recovered and recycled, rather than to be disposed of in landfill. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)
Open AccessReview Environmental Risk of Metal Mining Contaminated River Bank Sediment at Redox-Transitional Zones
Minerals 2014, 4(1), 52-73; doi:10.3390/min4010052
Received: 21 December 2013 / Revised: 21 January 2014 / Accepted: 22 January 2014 / Published: 29 January 2014
Cited by 9 | PDF Full-text (1092 KB) | HTML Full-text | XML Full-text
Abstract
Diffuse metal pollution from mining impacted sediment is widely recognised as a potential source of contamination to river systems and may significantly hinder the achievement of European Union Water Framework Directive objectives. Redox-transitional zones that form along metal contaminated river banks as [...] Read more.
Diffuse metal pollution from mining impacted sediment is widely recognised as a potential source of contamination to river systems and may significantly hinder the achievement of European Union Water Framework Directive objectives. Redox-transitional zones that form along metal contaminated river banks as a result of flood and drought cycles could cause biogeochemical changes that alter the behaviour of polyvalent metals iron and manganese and anions such as sulphur. Trace metals are often partitioned with iron, manganese and sulphur minerals in mining-contaminated sediment, therefore the dissolution and precipitation of these minerals may influence the mobility of potentially toxic trace metals. Research indicates that freshly precipitated metal oxides and sulphides may be more “reactive” (more adsorbent and prone to dissolution when conditions change) than older crystalline forms. Fluctuations at the oxic-anoxic interface brought about through changes in the frequency and duration of flood and drought episodes may therefore influence the reactivity of secondary minerals that form in the sediment and the flux of dissolved trace metal release. UK climate change models predict longer dry periods for some regions, interspersed with higher magnitude flood events. If we are to fully comprehend the future environmental risk these climate change events pose to mining impacted river systems it is recommended that research efforts focus on identifying the primary controls on trace metal release at the oxic-anoxic interface for flood and drought cycles of different duration and frequency. This paper critically reviews the literature regarding biogeochemical processes that occur at different temporal scales during oxic, reducing and dry periods and focuses on how iron and sulphur based minerals may alter in form and reactivity and influence the mobility of trace metal contaminants. It is clear that changes in redox potential can alter the composition of secondary iron and sulphur minerals and influence the sorption of toxic trace metals and susceptibility to dissolution when further redox potential changes occur. However further work is needed to determine: (i) The extent to which different duration and frequency of wet and dry cycles influences the dissolution and precipitation of iron and sulphur minerals in mining contaminated river bank sediment; (ii) The temporal effects on mineral reactivity (sorption capacity and susceptibility to dissolution); (iii) The key biogeochemical processes that control the mobility of contaminant trace metals under these dynamic redox potential conditions. Full article
(This article belongs to the Special Issue Mine Waste Characterization, Management and Remediation)

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