| 1. |
|
|
| 2. |
- Alakangas, Lena, et al.
(författare)
-
Estimation of temporal changes in oxidation rates of sulphides in copper mine tailings at Laver, Northern Sweden
- 2010
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 408:6, s. 1386-1302
-
Tidskriftsartikel (refereegranskat)abstract
- Tailings containing pyrrhotite were deposited in an impoundment at a copper mine at Laver, Northern Sweden, which operated between 1936 and 1946. Since then the oxidation of sulphides has acidified recipient water courses and contaminated them with metals. Measurements from surface water sampled in 1993, 2001 and 2004-05 from a brook into which the tailing impoundment drains indicate that the amounts of sulphide-associated elements such as Cu, S and Zn released into the brook have decreased over time, while pH has increased. The mass transport of S in the brook during 1993 and 2001 corresponded well with the amount of S estimated to be released from the tailings by oxidation. Secondary precipitates such as covellite and gypsum, which can trap sulphur, were shown in earlier studies to be present in only low amounts. The annual release of elements from the tailings was estimated from the volume of tailings assumed to oxidise each year, which depends on movement of the oxidation front with time. The results indicate that the oxidation rate in the tailings has decreased over time, which may be due to the increased distance over which oxygen needs to diffuse to reach unoxidised sulphide grains, or their cores, in the tailings.
|
|
| 3. |
|
|
| 4. |
- Alakangas, Lena, et al.
(författare)
-
Literature review on potential geochemical and geotechnical effects of adopting paste technology under cold climate conditions
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this literature review is to summarize the recent research regarding geochemical and geotechnical stability of paste tailings, identify knowledge gaps and future research needs. The present study has been conducted by the Division of Geosciences and Environmental Engineering together with the Division of Mining and Geotechnical Engineering at Luleå University of Technology on behalf of Boliden Mineral, LKAB and Outotec.A survey conducted by MEND (Mine Environment Neutral Drainage) in 2006 on the environmental effects related to the use of paste tailings summarizes that only a few studies had been performed about long-term effects on the surface and groundwater quality. Instead, the focus had been on the additives and the strength of the paste. It is still uncertain how the paste technology affects the long-term environmental stability from a geochemical point of view. Concerns regarding the stability of paste with high sulphide content are still relevant. Studies performed indicate that sulphide oxidation occurs within cemented paste as well as on the surface of non-cemented paste and cracks formed on the surfaces could induce oxidation. For cemented paste, metals released by sulphide oxidation might be sequestered due to high pH induced by the alkaline additives, but anion such as Se has been shown to be mobilized. The leachate has been shown to be near-neutral initially, but the neutrality decreases with time and probably metals sequestered in the matrix will also be released. Again, it should be noted that no long term study was performed on leaching of paste, cemented or uncemented. The longest leaching study was performed for one year. Arsenic has been proven to be retained in Ca-arsenates in cemented paste, but the long term stability of these precipitates is relatively unknown. Expanded secondary phases e.g. gypsum and ettringite have been observed to form when there is sulphate in the process or drainage of water. These phases could crack the paste, but, on the other hand, can also fill former cracks when deposited in layers. The effects of the formation of these phases are relatively uncertain in a long-term perspective. Presence of different elements such as ammonium, sulphates and metals in the water has been shown to negatively affect the curing process and therefore water is suggested to be treated before use. The presence of carbon dioxide during the paste formation could also affect the curing process, but could sequester metals in carbonate phases.Geotechnical and rheological properties of paste is well defined and documented. Several case studies have been found in literature providing valuable information about the details of the works being carried out. However, a difficulty has been noted during the investigation of the effects of cold climate conditions when current practice is applied in the colder parts of the world. It is not certain how some specific and vital parameters are going to be affected by cold temperatures. Parameters such as deposition slopes and deposition scheme, strength development of the paste are expected to be responsive to cold climate conditions. There are predictions about which properties are going to be affected in what way, but there is also a need to establish a scientific base for discussion. These have been highlighted as research needs and information gaps at the end of the report.
|
|
| 5. |
- Alakangas, Lena, et al.
(författare)
-
Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes
- 2013
-
Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 20:11, s. 7907-7916
-
Tidskriftsartikel (refereegranskat)abstract
- Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m3 tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH < 2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH > 9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation
|
|
| 6. |
- Alakangas, Lena, et al.
(författare)
-
Norrbottens malm- och mineralresurs och dess potentiella betydelse för innovation, samhälle och miljö
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Gruvindustrins betydelse för samhällsutveckling och infrastruktur i Sverige och inte minst i Norrbottens län är mycket stor. De geologiska förutsättningarna att hitta nya brytvärda förekomster i Norrbotten är goda. Länet är tillsammans med Västerbotten en av Europas viktigaste regioner för utvinning av metaller. Det syns också i den nyligen framtagna regionala mineralstrategin för Norrbotten och Västerbotten. Visionen för den regionala mineralstrategin: ”Genom långsiktigt hållbart nyttjande av Norrbottens och Västerbottens läns mineralresurser har ytterligare tillväxt skapats i regionen och hela Sverige. Vi har utvecklat och stärkt vår ställning som ledande gruv- och mineralnation.”Eftersom framtidspotentialen för gruvnäringen är mycket god men okunnigheten hos både allmänhet och beslutsfattare om näringens betydelse för innovation och samhällsutveckling är stor, kopplat med en utbredd oro för miljöpåverkan, måste dessa viktiga framtidsfrågor belysas. Med finansiering från Länsstyrelsen i Norrbotten bedrevs därför under första hälften av 2014 en förstudie som syftade till att sammanfatta kunskapsläget om framtidens gruvindustri i Norrbotten. Resultaten av förstudien redovisas i den här rapporten. En viktig slutsats är att det under nästa strukturfondsperiod (med start 2015) behövs ett framtidsinriktat forskningsprogram för att belysa de möjligheter som finns. Denna förstudie utgör grund för en kommande ansökan till strukturfonderna. Kompetensen som finns vid Luleå tekniska universitet, Sveriges centrum för gruvrelaterad forskning och utbildning, bör användas för att studera troliga framtidsmöjligheter och hur de ska kunna användas för att få en så positiv utveckling som möjligt för länet. Projektet bör innehålla följande tre huvudinriktningar, som naturligtvis hör ihop:Vilka malm- och mineralresurser finns det potential för i Norrbotten, och vilka kommer sannolikt att exploateras i framtiden?Vad kommer den exploateringen att ha för betydelse för innovation och samhällsutveckling?Vad kommer den exploateringen att få för miljöeffekter och hur ska man göra för att minska miljöbelastningen?En annan slutsats är att nedlagda gruvområden inte måste ses som förstörd natur. Betydande mervärden som gruvturism skulle kunna skapas om vilja, kreativitet och beslutsamhet finns. Detta är ett givet utvecklingsområde där småföretag och entreprenörer kan göra stor insats om de politiska och myndighetsmässiga förutsättningarna finns. Dessa aspekter skulle också kunna belysas i det föreslagna forskningsprogrammet eller i ett eget projekt.
|
|
| 7. |
- Alakangas, Lena, et al.
(författare)
-
Pilot-scale studies of different covers on unoxidised sulphide-rich tailings, northern Sweden : oxygen diffusion
- 2010
-
Ingår i: Mine Water and the Environment. - Ostrava : VSB - Technical University Ostrava, Faculty of Mining and Geology, Institute of Environmental Engineering. - 9788024817675 ; , s. 347-350
-
Konferensbidrag (refereegranskat)abstract
- The efficiency of five cover systems to decrease oxygen intrusion into sulphide-rich tailings was studied in pilot-scale test cells (5x5x3 m(3)). The covers consisted of clayey till, sewage sludge, fine-grained apatite concentrate or Trisoplast (a mixture of a polymer, bentonite and tailings sand) as sealing layers and unspecified till as protective cover. In one reference cell, tailings were uncovered. Oxygen concentrations below the entire covers were highest below the Trisoplast and apatite layers, and lowest below the sewage sludge layer. Effective diffusion coefficients (D-eff) and oxygen fluxes were estimated in the covers with non-oxygen-consuming sealing layers (clayey till and apatite). For the protective covers the Deff ranged between E-09 and E-07 m(2)/s, and for the sealing layers between E-10 and E-09 m(2)/s, and for the entire covers between E-10 and E-08 m(2)/s. Seasonal variations in D-eff were larger within the covers than between the different cover systems. Oxygen fluxes through the entire covers with clayey till and apatite ranged between 0.2 and 4 mole m(2)/year, which was a reduction of more than 99% compared to uncovered dry tailings.
|
|
| 8. |
- Alakangas, Lena, et al.
(författare)
-
Project: ERA-MIN project "Tools for sustainable gold mining in EU"
- 2014
-
Annan publikation (populärvet., debatt m.m.)abstract
- This research identifies and evaluates environmental impacts and economical challenges of gold mining in Finland, Sweden, Portugal, Romania, Poland and Ireland. The focus of this project is in gold exploration, mineral processing, water treatment, waste management, environmental monitoring, risk assessment and socio-economic impacts of gold mining. Finasieras av Vinnova
|
|
| 9. |
- Alakangas, Lena
(författare)
-
Project: Kolarctic ENBI EnviMIne
- 2014
-
Annan publikation (populärvet., debatt m.m.)abstract
- The objectives of the project are to develop a methodology for environmentally safe mine closure under specific conditions in the Barents region by cross border cooperation, exchange experiences and scientific knowledge.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Alakangas, Lena, et al.
(författare)
-
Simulation of pyrite oxidation in fresh mine tailings under near-neutral conditions
- 2012
-
Ingår i: Journal of Environmental Monitoring. - 1464-0325 .- 1464-0333. ; 14:8, s. 2245-2253
-
Tidskriftsartikel (refereegranskat)abstract
- Sulphidic residual products from ore processing may produce acid rock drainage, when exposed to oxygen and water. Predictions of the magnitude of ARD and sulphide oxidation rates are of great importance in mine planning because they can be used to minimize or eliminate ARD and the associated economic and environmental costs. To address the lack of field data of sulphide oxidation rate in fresh sulphide-rich tailings under near-neutral conditions, determination and simulation of the rate was performed in pilot-scale at Kristineberg, northern Sweden. The quality of the drainage water was monitored, along with oxygen and carbon dioxide concentrations. The chemical composition of the solid tailings was also determined. The field data were compared to predictions from simulations of pyrite oxidation using a 1-D numerical model. The simulations' estimates of the amount of Fe and S released over a seven year period (52 kg and 178 kg, respectively) were in reasonably good agreement with those obtained by analysing the tailings (34 kg and 155 kg, respectively). The discrepancy is probably due to the formation of secondary precipitates such as iron hydroxides and gypsum; which are not accounted for in the model. The observed mass transport of Fe and S (0.05 and 1.0 kg per year, respectively) was much lower than expected on the basis of the simulations and the core data. Neutralization reactions involving carbonates in the tailings result in a near-neutral pH at all depths except at the oxidation front (pH < 5), indicating that the dissolution of carbonates was too slow for the acid to be neutralized, which instead neutralized deeper down in the tailings. This was also indicated by the reduced abundance of solid Ca at greater depths and the high levels of carbon dioxide both of which are consistent with the dissolution of carbonates. It could be concluded that the near-neutral pH in the tailings has no decreasing effect on the rate of sulphide oxidation, but does reduce the concentrations of dissolved elements in the drainage water due to the formation of secondary minerals. This means that sulphide oxidation rates may be underestimated if determined from drainage alone.
|
|
| 13. |
- Jia, Yu, et al.
(författare)
-
Degradation of digested sewage sludge residue under anaerobic conditions for mine tailings remediation
- 2014
-
Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 72:9, s. 3643-3654
-
Tidskriftsartikel (refereegranskat)abstract
- Previous studies showed that 85 % of total organic matter (TOM) in digested sewage sludge (biosolids) used as a sealing layer material over sulfide tailings at the Kristineberg Mine, northern Sweden had been degraded 8 years after application, resulting in a TOM reduction from 78 % to 14 %. To achieve a better understanding of the field observations, laboratory studies were performed to evaluate biodegradation rates of the TOM under anaerobic conditions. Results reveal that the original biosolid consisted of ca. 60 % TOM (48.0 % lignin and 11.8 % carbohydrates) that had not been fully degraded. The incubation experiments proved that 27.8 % TOM in the biosolid was further degraded anaerobically at 20-22 C during the 230 d incubation period, and that a plateau to the biodegradation rate was approached. Based on model results, the degradation constant was found to be 0.0125 (day-1). The calculated theoretical gas formation potential was ca. 50 % higher than the modeled results based on the average degradation rate. Cumulated H2S equated to 0.65 µmoL*g-1 of biosolid at 230 d. However, the large sulfurous compounds reservoir (1.76 g SO42- kg-1 biosolid) together with anaerobic conditions, can generate high concentrations of this gas over a long-term perspective. Due to the rate of biodegradability identified via anaerobic processes, the function of the biosolid to serve as an effective barrier to inhibit oxygen migration to underlying tailings, may decrease over time. However, a lack of readily degradable organic fractions in the biosolid and a large fraction of organic matter that was recalcitrant to degradation suggests a longer degradation duration, which would prolong the biosolid material’s function and integrity.
|
|
| 14. |
- Lu, Jinmei, et al.
(författare)
-
Evaluation of the application of dry covers over carbonate-rich sulphide tailings
- 2013
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 244-245, s. 180-194
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, four ten years test areas with covered tailings were geochemically evaluated. Three areas were covered with a fly ash and an overlying sludge layer, and one only with a sludge cover, originating from paper mills. The accumulation of As, Fe and Pb in sludge layers, originating from air-borne dust and the depletion of K, Na and P from both cover layers were observed. High release of elements from tailings was observed in the comparison profile due to oxidation and weathering of tailings. In only sludge covered area, the leaching of elements from tailings decreased. In the profiles with thin ash (20 cm and 30 cm), most elements were retained in tailings with pH 7-9. In the profile with the thickest ash (50 cm), elements such as As, Cd, Cu, Mg, Mn, Pb, S and Zn were depleted in the uppermost tailings with pH above 11 and retained deeper in the zone with pH 7-8, which implied that large quantities of fly ash increased the oxidation and weathering of tailings and mobility of elements. Elements excluding K, never reached the groundwater in high concentrations in the covered areas, while the comparison area had high Ca, K, Mn and S concentrations
|
|
| 15. |
- Lu, Jinmei, et al.
(författare)
-
Metal mobilization under alkaline conditions in ash-covered tailings
- 2014
-
Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 139, s. 38-49
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings
|
|
| 16. |
- Nason, Peter, et al.
(författare)
-
Alternative Waste Residue Materials for passive in-situ prevention of sulfide-mine tailings oxidation : A Field Evaluation
- 2014
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 267, s. 245-254
-
Tidskriftsartikel (refereegranskat)abstract
- Novel solutions for sulfide-mine tailings remediation were evaluated in field-scale experiments on a former tailings repository in northern Sweden. Uncovered sulfide-tailings were compared to sewage-sludge biosolid amended tailings over 2 years. An application of a 0.2 m single-layer sewage-sludge amendment was unsuccessful at preventing oxygen ingress to underlying tailings. It merely slowed the sulfide-oxidation rate by 20%. In addition, sludge-derived metals (Cu, Ni, Fe, and Zn) migrated and precipitated at the tailings-to-sludge interface. By using an additional 0.6 m thick fly-ash sealing layer underlying the sewage sludge layer, a solution to mitigate oxygen transport to the underlying tailings and minimize sulfide-oxidation was found. The fly-ash acted as a hardened physical barrier that prevented oxygen diffusion and provided a trap for sludge-borne metals. Nevertheless, the biosolid application hampered the application, despite the advances in the effectiveness of the fly-ash layer, as sludge-borne nitrate leached through the cover system into the underlying tailings, oxidizing pyrite. This created a 0.3 m deep oxidized zone in 6-years. This study highlights that using sewage sludge in unconventional cover systems is not always a practical solution for the remediation of sulfide-bearing mine tailings to mitigate against sulfide weathering and acid rock drainage formation
|
|
| 17. |
- Nason, Peter, et al.
(författare)
-
Assessing the impact of sewage sludge on a formally remediated tailings impoundment in relation to the transport of metals in groundwater
- 2011
-
Ingår i: Mine Water - managing the Challenges. - Aachen, Germany : RWTH Aachen University, Institute of Hydrogeology. - 9783000355431 ; , s. 429-434
-
Konferensbidrag (refereegranskat)abstract
- In 2009 sewage sludge was applied to an already successfully remediated saturated and dry covered sulphide tailings impoundment in northern Sweden as a vegetation substrate. The aim of this study was to identify the dispersion, magnitude and duration of sludge-borne constituents released. Readily leachable sludge-borne constituents (DOC, Fe, Co, Cr, Ni, Pb and Zn) created a contamination plume which affected the impoundment groundwater within the first year of application. The majority of the plume originated from the water-saturated area of the impoundment that was only covered with a 10% surface area of sludge. The dry-composite covered area of the impoundment, which contained a 70% sludge cover, did not contribute to the contamination plume due to the efficiency of the cover at reducing water infiltration and contamination dispersal. The constituents were transported along the dominant groundwater flow direction, underneath the dry covered area of the impoundment, to the effluent of the impoundment groundwater system due to inflowing uncontaminated groundwater from an adjacent till slope. All metal and DOC concentrations in the impoundment groundwater returned to pre-sludge application concentrations within two years, due to successful plant establishment on the sludge.
|
|
| 18. |
- Nason, Peter, et al.
(författare)
-
Impact of Sewage Sludge on Groundwater Quality at a Formerly Remediated Tailings Impoundment
- 2014
-
Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 33:1, s. 66-78
-
Tidskriftsartikel (refereegranskat)abstract
- Sewage sludge can be a suitable, organic-rich substrate to promote vegetation ofsulfide-mine tailings, but it may contain contaminants, that, when oxidized, canadversely affect underlying groundwater systems. The geochemical impact of asurface application of 12,000 metric tons of anaerobically-digested sewage sludge on the groundwater quality of a remediated sulfide-tailings impoundment in northern Sweden was evaluated to determine if sludge-borne metals and nitrate were released to the underlying groundwater system. Two years of data from a field-scale groundwater monitoring programme initiated just before the sludge application was compared to groundwater data from 1998-2006. Grass was successfully established within two years. However, until that occurred, elevated concentrations of sludge-borne metals (Cu, Ni, Pb, Zn) were released to the underlying groundwater. In addition, the release of nitrate likely exacerbated metal concentrations by providing an oxidant for pyrite in the underlying tailings. The release was periodic due to the establishment of the grass, which immobilized metals and nitrate in the sludge. Metals bound asorgano-metallic complexes, due to dissolved organic carbon released from the sludge, migrated across the tailings impoundment. Model simulations indicate that the plume will take six years to exit the groundwater environment. Though the impacts are relatively short-term, this type of application should be reconsidered in the future.
|
|
| 19. |
- Nason, Peter, et al.
(författare)
-
Sewage sludge as a sealing layer for the remediation of sulphide-bearing mine tailings : ageing and degradation of the barrier material
- 2011
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Using sewage sludge as an organic barrier to mitigate oxygen diffusion to underlying sulphidic tailings was performed in experimental pilot-scale test cells, northern Sweden and was proved to be successful over an 8 year period (Nason et al., 2010). However, degradation and ageing of the sewage sludge may limit its function in the long-term as indicated by surface applications of sewage sludge, as the exposure of the material to atmospheric oxygen may cause aerobic degradation of the organic matter fraction (Peppas et al., 2000), nitrification (Cravotta, 1998) and subsequent structural disintegration (Ahlberg, 2006). A pilot-scale test cell with a 0.3m sewage sludge sealing layer capped by a 1.2m protective layer of glacial till was used to cover tailings. Quantification of the changing properties of the sewage sludge after an 8 year period occurred using temperature data and solid sludge and leachate geochemistry. It was found that all layers were frozen between December to April and that a perched water table formed above the sealing layer from April to August (Shcherbakova, 2006). The subsequent lack of contact of the sludge with oxygen minimised aerobic degradation of the organic fraction, prevented nitrification and created an anoxic environment in the sludge. Nitrate in the leachate was <1mg/l and the subsequent lack of acidification created a neutral pH in the sludge and underlying tailings. Elevated alkalinity (360-600 mg/l) and low sulphate (9-67 mg/l) in the leachate indicated that sulphate reduction by anaerobic degradation of the organic matter had occurred in the sludge. On average, the organic fraction was reduced by 80%, but was most prevalent at the sludge to tailings interface where 92% of the organic matter had been lost since deposition. Mass balance calculations of the sludge revealed a 19.6% total loss of volume due to the organic matter degradation and leaching of Cd, Cu, Hg, Zn and P that were elevated in the original sludge material. No structural degradation as experienced by surface applications such as shrinkage or cracking occurred as the barrier was not exposed to oxygen. The integrity and function of the sub-surface sewage sludge layer was less compromised compared to a surface layer as degradation was dominated by anaerobic processes. However, organic degradation rates were high and it is recommended that this type of application is effective only as a medium-term solution for mitigating oxygen diffusion to underlying sulphidic tailings and for preventing acid rock drainage. Ahlberg, G. (2006). Göteborg University. Doctoral Thesis: 20. Cravotta, C. A. 1998. Ground Water 36(1): 9-19. Nason et al., 2010. IMWA 2010: Nova Scotia, Canada, Cape Breton University Press. Peppas et al., 2000. Minerals Engineering 13(5): 563-574. Shcherbakova, E. 2006. Luleå University of Technology. Doctoral Thesis
|
|
| 20. |
- Nason, Peter, et al.
(författare)
-
The effectiveness of using sewage sludge as a sealing layer on sulphide-rich mine tailings : a pilot-scale experiment, northern Sweden
- 2010
-
Ingår i: Mine Water in Innovative Thinking. - Sydney, Nova Scotia : Cape Breton Univ. Press. - 9781897009475 ; , s. 155-158
-
Konferensbidrag (refereegranskat)abstract
- En utvärdering av effektiviteten av att använda avloppsslam som tätskikt för att hindra syre spridning till underliggande avfall genomfördes under perioden 2001-2009 med pilotskala celler i norra Sverige. Lakvattnet dränering av ett oskyddat bearbetningsavfall kontroll cell och en cell med en 0.25m tätskikt av avloppsslam analyserades utifrån 2003-2009. En första hög koncentration spola av lösta element förekom i båda cellerna. Svavel och kraftiga koncentrationer metal gradvis minskat i både celler men skillnaderna i halter var flera storleksordningar lägre för slammet saneras cellen. Cd-Fe-Zn koncentrationer i kontrollen ökat över tid på grund av svaveloxidering. Konsumtionen av syre i avloppsslam som skapats minskas förhållanden på de underliggande bearbetningsavfall. Förhöjda metallhalter lakas ur slammet i bearbetningsavfall därefter kvar i den anrikningssand och var inte förhöjda i utflödet lakvattnet lösningen.
|
|
| 21. |
- Nason, Peter, et al.
(författare)
-
Using sewage sludge as a sealing layer to remediate sulphidic mine tailings : a pilot-scale experiment, northern Sweden
- 2013
-
Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 70:7, s. 3093-3105
-
Tidskriftsartikel (refereegranskat)abstract
- At the Kristineberg mine, northern Sweden, sulphidic mine tailings were remediated in an 8-year pilot-scale experiment using sewage sludge to evaluate its applicability as a sealing layer in a composite dry cover. Sediment, leachate water, and pore gas geochemistry were collected in the aim of determining if the sludge was an effective barrier material to mitigate acid rock drainage (ARD) formation. The sludge was an effective barrier to oxygen influx as it formed both a physical obstruction and functioned as an organic reactive barrier to prevent oxygen to the underlying tailings. Sulphide oxidation and consequential ARD formation did not occur. Sludge-borne trace elements accumulated in a reductive, alkaline environment in the underlying tailings, resulting in an effluent drainage geochemistry of Cd, Cu, Pb and Zn below 10 μg/L, high alkalinity (810 mg/L) and low sulphate (38 mg/L). In contrast, the uncovered reference tailings received a 0.35-m deep oxidation front and typical ARD, with dissolved concentrations of Cd, Zn and sulphate, 20.8 μg/L, 16,100 μg/L and 1,390 mg/L, respectively. Organic matter degradation in the sludge may be a limiting factor to the function of the sealing layer over time as 85 % loss of the organic fraction occurred over the 8-year experimental period due to aerobic and anaerobic degradation. Though the cover may function in the short to medium term (100 years), it is unlikely to meet the demands of a long-term remedial solution
|
|
| 22. |
- Pérez Rodríguez, Nathalie, et al.
(författare)
-
The role of bacterial consortium and organic amendment in Cu and Fe isotope fractionation in plants on a polluted mine site
- 2014
-
Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 21:11, s. 6836-6844
-
Tidskriftsartikel (refereegranskat)abstract
- Copper and iron isotope fractionation by plant uptake and translocation is a matter of current research. As a way to apply the use of Cu and Fe stable isotopes in the phytoremediation of contaminated sites, the effects of organic amendment and microbial addition in a mine spoiled soil seeded with Helianthus annuus in pot experiments and field trials were studied. Results show that the addition of a microbial consortium of ten bacterial strains has an influence on Cu and Fe isotope fractionation by the uptake and translocation in pot experiments, with an increase in average of 0.99‰ for the δ65Cu values from soil to roots. In the field trial, the amendment with the addition of bacteria and mycorrhiza as single and double inoculation enriches the leaves in 65Cu compared to the soil. As a result of the same trial, the δ56Fe values in the leaves are lower than those from the bulk soil, although some differences are seen according to the amendment used. Siderophores, possibly released by the bacterial consortium, can be responsible for this change in the Cu and Fe fractionation. The overall isotopic fractionation trend for Cu and Fe does not vary for pots and field experiments with or without bacteria. However variations in specific metabolic pathways related to metal-organic complexation and weathering can modify particular isotopic signatures.
|
|
| 23. |
- Rodríguez, Nathalie Pérez, et al.
(författare)
-
Copper and iron isotope fractionation in mine tailings at the Laver and Kristineberg mines, northern Sweden
- 2013
-
Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 32, s. 204-215
-
Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that Cu and Fe isotopes are fractionated by dissolution and precipitation reactions driven by changing redox conditions. In this study, Cu isotope composition (65Cu/63Cu ratios) was studied in profiles through sulfide-bearing tailings at the former Cu mine at Laver and in a pilot-scale test cell at the Kristineberg mine, both in northern Sweden. The profile at Kristineberg was also analysed for Fe isotope composition (56Fe/54Fe ratios). At both sites sulfide oxidation resulted in an enrichment of the lighter Cu isotope in the oxidised zone of the tailings compared to the original isotope ratio, probably due to preferential losses of the heavier Cu isotope into the liquid phase during oxidation of sulfides. In a zone with secondary enrichment of Cu, located just below the oxidation front at Laver, δ65Cu (compared to ERM-AE633) was as low as -4.35 ± 0.02‰, which can be compared to the original value of 1.31 ± 0.03‰ in the unoxidised tailings. Precipitation of covellite in the secondary Cu enrichment zone explains this fractionation. The Fe isotopic composition in the Kristineberg profile is similar in the oxidised zone and in the unoxidised zone, with average δ56Fe values (relative to the IRMM-014) of -0.58± 0.06‰ and -0.49 ± 0.05‰, respectively. At the well-defined oxidation front, δ56Fe was less negative, -0.24 ± 0.01 ‰. Processes such as Fe(II)-Fe(III) equilibrium and precipitation of Fe-(oxy)hydroxides at the oxidation front are assumed to cause this Fe isotope fractionation. This field study provides additional support for the importance of redox processes for the isotopic composition of Cu and Fe in natural systems.
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
- Villain, Lucile, et al.
(författare)
-
Evaluation of the effectiveness of backfilling and sealing at an open-pit mine using ground penetrating radar and geoelectrical surveys, Kimheden, northern Sweden
- 2014
-
Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 73:8, s. 4495-4509
-
Tidskriftsartikel (refereegranskat)abstract
- At Kimheden, a small copper mine in northern Sweden, reclamation of the two open pits was investigated using ground penetrating radar and geoelectrical multiple-gradient array measurements. The pits had been backfilled with waste rock, with a dry cover being applied on top in 1996 in order to reduce the influx of oxygen to the sulphidic mine waste and the subsequent production of acid mine drainage. The dry cover consists of a sealing layer of clayey till and a protective layer of unsorted till. As geochemical sampling in the drainage from the pits had previously revealed the continued release of contaminating oxidation products, the purpose of the geophysical survey undertaken in 2010 was to identify deficiencies in the cover or other pathways for oxygen to reach the waste rock. The radar images did not reveal any damage in the sealing layer but risks of deterioration of the cover in the long term were identified with both the radar and geoelectrical data. The radar localised regions of thinner protective layer where the sealing layer could be exposed to frost action. The geoelectrical measurements indicated the existence of seepage through the dry cover that presented a risk of erosion of the sealing layer. 2-D inversion of geoelectrical data also imaged some pathways of groundwater around the main pit. The results from the geophysical investigations were used together with other site data in order to show that both deficiencies in the cover and superficial fractures in the pit walls may explain an ongoing influx of oxygen to the mine waste.
|
|
| 28. |
- Villain, Lucile, et al.
(författare)
-
Geochemical evaluation of mine water quality in an open-pit site remediated by backfilling and sealing
- 2010
-
Ingår i: Mine water & innovative thinking. - : Cape Breton University Press. - 9781897009475 - 9781897009475 ; , s. 515-518
-
Konferensbidrag (refereegranskat)abstract
- En geokemisk utvärdering av gruvvattenkvaliteten i ett efterbehandlat dagbrott, Kimheden, genomfördes år 2009. Kimheden är en liten koppargruva som är belägen i Västerbotten, Norra Sverige, som var i produktion under 70-talet för Boliden AB. Den återfylldes av gråberg och förseglades med lerig morän 1996. Ytvatten- och grundvattenprover togs på plats under sommaren 2009. Det har dessutom genomförts regelbunden provtagning av områdets huvudvattendrag av Boliden AB sedan 1983. Resultaten visar att metall koncentrationerna minskade samt att pH-värdet ökade efter genomförd efterbehandling, vilket indikerar en fördelaktig utveckling av vattenkvaliteten.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Villain, Lucile, et al.
(författare)
-
The effects of backfilling and sealing the waste rock on water quality at the Kimheden open-pit mine, northern Sweden
- 2013
-
Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742 .- 1879-1689. ; 134, s. 99-110
-
Tidskriftsartikel (refereegranskat)abstract
- Evaluating the water quality at reclaimed mines affected by acid mine drainage is an essential step in assessing and improving the performance of mitigation techniques. At the Kimheden copper mine in northern Sweden, reclamation involved the progressive backfilling of waste rock into the two small open pits and, in 1996, the application of a till dry cover that included a sealing layer. The data from both the long-term water quality monitoring by the mining company and the repeated sampling of the surface water and groundwater in 2009 and 2010 were used to assess the success of the reclamation in mitigating the acid mine drainage production from the mine waste. A substantial decrease in the concentrations of copper, zinc and sulphate ions by 95%, 81% and 81%, respectively followed by a rapid stabilisation of element concentrations was observed at the outlet of the receiving stream since early reclamation times. This trend initially suggested successful results for the reclamation, though another explanation for the diminution of contaminant release through depletion of the limited sulphidic source could not be neglected. However, in spite of the decrease, post-reclamation metal concentrations in the stream are still not satisfactory for the discharge of the mine drainage into the natural environment, indicating that the mitigation measures were insufficient. Seepage from one of the pits in 2009 had dissolved copper, aluminium and zinc concentrations of 1.6 mg/L, 4.4 mg/L and 0.45 mg/L, respectively and a pH of 3.0. Relatively high dissolved oxygen concentrations in the groundwater of the backfill in 2009 and 2010 (> 2 mg/L) suggest that the mixed outcome of the mitigation actions is due to on-going oxidation in the backfilled waste rock despite the dry cover. Moreover, stream discharge and dissolved sulphate and magnesium used as natural tracers in the drainage showed that water management in the form of ditches is not appropriate. In particular, due to poor sealing of the ditches, whilst a measurable part of the contaminated drainage in the collecting ditch is leaking to groundwater and dispersing in the surrounding natural areas, the water discharged to a treatment pond at the outlet of the stream is mostly uncontaminated background water.
|
|
| 32. |
- Öhlander, Björn, et al.
(författare)
-
Fractionation of trace metals in a contaminated freshwater stream using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss
- 2012
-
Ingår i: Geochemistry. - : Geological Society of London. - 1467-7873 .- 2041-4943. ; 12:4, s. 303-312
-
Tidskriftsartikel (refereegranskat)abstract
- Four metal speciation and fractionation techniques – DGT (diffusive gradients in thin films), 1-kDa ultrafiltration, 0.22-µm membrane filtration and aquatic moss – were simultaneously applied to a small, contaminated freshwater stream in northern Sweden to investigate differences and similarities between the methods regarding trace metal speciation and their dependence on geochemical water properties. The investigated metals comprise Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn. The normal DGT devices with Chelex cation exchanger were used. Shoots from the aquatic moss Fontinalis antipyretica L ex Hedw. were collected in a non-polluted brook and transplanted to the sampling site for exposure. It was evident that 0.22-µm membrane filtration, 1-kDa ultrafiltration and DGT generally measured different metal fractions where <1-kDa ultrafiltered concentrations were lower than DGT labile concentrations which in turn were lower than <0.22-µm concentrations. The differences between DGT and <1-kDa concentrations indicate the occurrence of labile colloids discriminated by ultrafiltration. Strong correlations between DGT and <1 kDa concentrations were found for Al, Cu, Cd, Co and Zn. Despite a rigorous sample cleaning, retention of particulate matter on the moss samples was revealed by a significant correlation between metal concentrations in moss and particulate Fe. Generally, elevated trace metal concentrations were found in moss exposed at the sampling site compared to reference moss from the non-polluted brook. No significant correlations were found between DGT-labile concentrations and moss concentrations.
|
|
| 33. |
- Öhlander, Björn, et al.
(författare)
-
Management of Sulfide-Bearing Waste, a Challenge for the Mining Industry
- 2012
-
Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 2:1, s. 1-10
-
Forskningsöversikt (refereegranskat)abstract
- Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.
|
|
| 34. |
|
|
| 35. |
|
|
