1. |
- Alakangas, Lena, et al.
(författare)
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Pilot-scale studies of different covers on unoxidised sulphide-rich tailings in northern Sweden : the geochemistry of leachate waters
- 2006
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 25:3, s. 171-183
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Tidskriftsartikel (refereegranskat)abstract
- Leachate water quality from covered and uncovered unoxidised sulphide-rich tailings in six pilot-scale (5x5x3 m3) test cells was monitored during 2004 and 2005. The covers consisted of a layer of clayey till, sewage sludge, apatite or Trisoplast (a commercial mixture of tailings, bentonite, and a polymer). All layers were protected by an unspecified till except in one reference cell, where the tailings were left open. All leachate waters showed near-neutral pH as a result of neutralization by calcite in the tailings and by Ca(OH)2 added prior to deposition. Average dissolved sulphur concentrations in the leachates were ≈ 600 mg L-1, except in the cell with sewage sludge (300 mg L-1). The source of sulphur was mainly pyrite oxidation, but residual sulphur probably remained from the enrichment process. The near-neutral pH favoured precipitation of metal-(oxy)hydroxides with subsequent removal of trace elements such as Cd, Cu and Pb (< 15 μg L-1) from the solutions. High concentrations of Co, Mn, Ni, and Zn were found in leachates from the apatite, Trisoplast, and uncovered tailings cells. High As concentrations were found in the leachates in the sewage sludge and clayey till cells. The lowest metal concentrations, redox potential, and highest pH were found in the sewage sludge cell. Decreased elemental metal concentrations during 2004 suggest improved performance over time.
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3. |
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4. |
- Hällström, Lina P.B.
(författare)
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Mobility of Be, Bi, F, Ga, Ge and W in Surface Water and the Water Quality Impact on Epilithic Diatoms Downstream of the Historical Yxsjoberg Mine Site, Sweden
- 2022
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Ingår i: Mine Water and the Environment. - : Springer Nature. - 1025-9112 .- 1616-1068. ; 41:3, s. 731-747
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Tidskriftsartikel (refereegranskat)abstract
- There is a potential risk that the geochemical cycles of several critical metals will be affected when mining of these metals increases to meet the demand of green technology. The geochemistry of Be, Bi, Ga, Ge, and W, herewith called CM5, is lacking, yet is necessary to ensure responsible mine waste and water management. Beryllium, Bi, and W are all considered immobile, but in previous studies of skarn tailings in Yxsjoberg, Sweden, all three elements were mobilized. The tailings are enriched in CM5, together with pyrrhotite, calcite, and fluorite. The mobility and environmental impact of CM5 and F in surface waters downstream of the Yxsjoberg mine site, Sweden, were studied using monthly water samples from seven locations and analysis of diatoms at five of these locations. Bismuth, Ge, and W were present at low concentrations, transported in the particulate phase, and likely settled in the sediments hundreds of meters from the tailings. Beryllium and F were present at high concentrations and dominantly transported in the dissolved phase. At these pH conditions (5.6), Be should form insoluble hydroxides; however, elevated concentrations of dissolved Be were observed more than 5 km from the mine site. Diatoms downstream of the mine site were negatively affected by the mine drainage. The release of low quality neutral mine drainage will continue for hundreds of years if remediation actions are not undertaken since only a small portion of the tailings have weathered during 50-100 years of storage.
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5. |
- Jia, Yu, et al.
(författare)
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Metal Mobilization in Tailings Covered with Alkaline Residue Products : Results from a Leaching Test Using Fly Ash, Green Liquor Dregs, and Lime Mud
- 2015
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 34:3, s. 270-287
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Tidskriftsartikel (refereegranskat)abstract
- The in situ dynamics of repeated percolation of rainwater through unoxidized mine tailings was simulated using a modified column test to predict long-term weathering characteristics. Fly ash, green liquor dregs, and lime mud waste materials from the paper mill industry were used in the column tests to assess the effect of alkaline paper mill residue on pH buffering and controlling the mobility of metals and semi-metals from the tailings. The experiment was continued for 15 cycles, each comprising reaction, leaching, and idle steps (1 week per step). The cumulative percolated water through the tailings represented a liquid:solid ratio of 1.6. The leached content of inorganic elements decreased with time in both the covered and the uncovered tailings. The presence of the alkaline materials consistently reduced the mobility of most contaminants (e.g. Cd, Co, Cr, Mn, Ni and Zn), but not As. The leachate was modeled using PHREEQC. XRD analysis of the remaining tailings samples after termination of the test showed detectable variations in mineral composition. The alkaline residue products all fulfilled the requirements as a cover material from a geochemical prospective, with the exception of As. The green liquor dregs and lime cover increased the pH of the tailings more rapidly than did the fly ash.
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6. |
- Karlsson, Teemu, et al.
(författare)
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A Test of Two Methods for Waste Rock Drainage Quality Prediction: Aqua Regia Extraction and Single-addition Net-acid Generation Test Leachate Analysis : [两种废矿石排水质量预测方法: 王水提取法和单添加净产酸实验 (NAG) 滤出液分析法] [Ein Test von zwei Methoden zur Qualitätsvorhersage von Haldensickerwässern: Königswasseraufschluss und Sickerwasseranalyse über den Nettosäurebildungspotentialtest bei einmaliger Zugabe]
- 2021
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Ingår i: Mine Water and the Environment. - : Springer. - 1025-9112 .- 1616-1068. ; 40:3, s. 736-751
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Tidskriftsartikel (refereegranskat)abstract
- The mobility of contaminants from mine waste can be assessed using different extraction methods. Aqua regia (AR) extraction is the most commonly used method in Finland. Another method is the analysis of leachate from net acid generation (NAG) tests, which is primarily designed for acid production potential assessment. We investigated the performance of single-addition NAG test leachate analysis and AR extraction in drainage quality prediction, using waste rock and drainage water samples from several Finnish waste rock sites. Our objective was to improve interpretation of the AR and single-addition NAG test leachate analysis results in drainage quality prediction. The AR extraction effectively reflected elements that occurred in elevated concentrations in drainage water, though it over-predicted Al, As, Cd, Co, Cu, and Ni in some circumneutral drainages, and Cr in general. The single-addition NAG test leachate analysis also performed well in assessing the mobility of contaminants including Al and Cr at acid mine drainage sites. As the contaminants tend to precipitate in neutral NAG test solution, the usability of the method in neutral mine drainage cases should be further investigated. Furthermore, the conclusions presented in this study are limited to waste rock samples collected from the surface of piles; future work will examine waste rock history, dump cores, drainage quality changes, etc. in more detail.
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7. |
- Mäkitalo, Maria, et al.
(författare)
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An Evaluation of Using Various Admixtures of Green Liquor Dregs, a Residual Product, as a Sealing Layer on Reactive Mine Tailings
- 2016
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 35:3, s. 283-293
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Tidskriftsartikel (refereegranskat)abstract
- Green liquor dregs (GLD), a residual product from sulfate paper mills, was blended with tailings, fly ash, and bark sludge with the aim of improving the material’s physical properties so that it could function as a sealing layer in dry covers on sulfidic mine waste. Geotechnical and geochemical investigations, including weathering cell tests, were carried out on GLD with admixtures to assess their effectiveness. Due to its alkaline character, GLD was shown to have the potential to improve leachate quality by decreasing metal mobility when blended with tailings. The admixtures showed favorable sealing layer properties such as high water retention capacity and low hydraulic conductivity. However, caution must be exercised when the dregs are blended with tailings containing large amounts of As and Mo, since increased leaching of these elements may be expected.
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8. |
- Nason, Peter, et al.
(författare)
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Biodegradation of Biosolids Under Aerobic Conditions : Implications for Cover Materials for Sulfide Mine Tailings Remediation
- 2016
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 35:3, s. 273-282
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Tidskriftsartikel (refereegranskat)abstract
- Sewage sludge residue (biosolids) was investigated for its potential as a long-term tailings cover. Biosolids may prevent oxygen diffusion into underlying sulfide tailings through microbial aerobic biodegradation of organic matter. Biosolids were investigated at laboratory-, pilot-, and field-scale using analysis of total organic matter (TOM) mass reduction and O2, CO2, CH4 concentrations to quantify the biodegradation rate. A 156-day, open microcosm experiment, in which the loss of biosolids mass over time at differing temperatures, mimicking ambient (20–22 °C), mesophilic (34 °C), and thermophilic (50 °C) conditions, indicated that TOM biodegradation was best in the mesophilic temperature range, with 14.8, 27.2, and 26.7 % mass depletion at ambient, mesophilic, and thermophilic conditions, respectively. The data was correlated to field-scale data that evaluated biodegradation rates via decreasing O2 and increasing CO2 concentrations. Field biodegradation rates were less than laboratory rates because lower mean annual temperatures (0.6–0.7 °C) diminished microbial activity. A calibrated model indicates that 20 % of a field application of biosolids will degrade within 2 years. However, the rate declines with time due to exhaustion of the most readily degradable organic fraction. If biodegradation cannot be maintained, the long-term effectiveness of biosolids as a covering material for mine tailings remains a concern.
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9. |
- Nason, Peter, et al.
(författare)
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Impact of Sewage Sludge on Groundwater Quality at a Formerly Remediated Tailings Impoundment
- 2014
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 33:1, s. 66-78
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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.
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10. |
- Nhantumbo, Clemencio, et al.
(författare)
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A Simplified Model to Simulate pH and Alkalinity in the Mixing Zone Downstream of an Acidic Discharge
- 2018
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 37:3, s. 552-564
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Tidskriftsartikel (refereegranskat)abstract
- A modelling methodology was developed that simulates the resulting pH and alkalinity in the mixing zone when acidic water is discharged into a river. The input to the model are the: pH, alkalinity, flow, and temperature of both the river water and the acidic discharge. Two different scenarios were simulated: (1) a change of pH in the acidic discharge, assuming constant flow; and (2) a change in the flow of the acidic discharge, assuming constant pH. The model incorporates the effect of carbonic acid and the modelled values agree well with the laboratory results. The model setup was subsequently used to predict the anticipated effect of contamination of the Zambezi River in Mozambique. The results indicate that the river will be impacted if the average pH of the water in the tributaries coming from the mining area is below 3. The model could be used by water managers to predict the potential impact of acidic discharges in poorly monitored rivers.
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11. |
- Nigéus, Susanne, et al.
(författare)
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Instrumentation of Sealing Layers Made of Two Different Amendments (Green Liquor Dregs and Bentonite) to Till for Reclamation of Sulfidic Mine Waste
- 2023
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Ingår i: Mine Water and the Environment. - : Springer Nature. - 1025-9112 .- 1616-1068. ; 42:3, s. 441-448
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, a dry cover solution is commonly used to stop sulfide oxidation and the production of acid rock drainage from unattended sulfidic mine waste. Recycling a non-hazardous industrial residue, such as green liquor dregs (GLD) generated during pulp production, in this cover solution is beneficial for both the mining industry where there is a great need for cover materials and the pulp production industry. The objectives of this field study were to install and evaluate the instrumentation of sealing layers made of GLD- and bentonite-amended till, and to evaluate the practical aspects of two different methods of installation: monitoring wells and pits. This practical field study demonstrated that it is difficult to properly seal the drill holes after installing the probes in observation wells and suggests that a better (easier and less costly) alternative for future instrument installation in a sealing layer might be to excavate a pit in the protective layer after installation of the soil cover and then drill the probes into the sealing layer from that pit.
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12. |
- Nigéus, Susanne, et al.
(författare)
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The Drivers of Hydraulic Conductivity in Green Liquor Dregs Amended Till: Application to Reclamation of Acid Generating Mine Sites
- 2023
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Ingår i: Mine Water and the Environment. - : Springer. - 1025-9112 .- 1616-1068. ; 42, s. 59-69
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Tidskriftsartikel (refereegranskat)abstract
- The mining industry produces massive amounts of waste that in contact with oxygen can result in leaching of metals. Access to a suitable cover-material for the mine waste is sometimes limited, creating a driving force for recycling industrial residues for these purposes. Green liquor dregs (GLD), an industrial residue from paper and pulp production, has the potential to be used in a sealing layer as an amendment to till. Though hydraulic conductivity is commonly used to evaluate the quality of the sealing layer, field application from laboratory investigations is challenging as many factors, apart from vast variations in the physical properties of both the till and the GLD, control hydraulic conductivity. In this study, 5–20 wt.% of GLD from two different paper mills, with different total solid contents and particle size distributions, were mixed with a silty till with varying total solid contents to investigate how the materials’ dry density, initial water content, and compaction affects the hydraulic conductivity. We found that the initial water content of the materials was the most important factor. With a drier till and GLD, more GLD should be added to attain the lowest hydraulic conductivity possible. The compaction was not found to notably affect the mixtures’ hydraulic conductivity.
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13. |
- Sartz, Lotta, 1979-, et al.
(författare)
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Mixing of acid rock drainage with alkaline leachates : Formation of solid precipitates and pH-buffering
- 2016
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Ingår i: Mine Water and the Environment. - : Springer. - 1025-9112 .- 1616-1068. ; 35:1, s. 64-76
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Tidskriftsartikel (refereegranskat)abstract
- Three metal-rich, acidic mine waters (from Bersbo and Ljusnarsberg, Sweden) were mixed with alkaline fly ash leachates in various proportions, representing a pH titration. Changes in pH and the loss of metals in solution due to precipitation of solid phases were tracked. Mineral equilibria and changes in pH and alkalinity were simulated using the geochemical code PHREEQC and the MINTEQv4 database, and the measured and simulated pH responses were compared. The formation of solid precipitates corresponded to fairly well-defined pH-buffering regions, reflecting the mine water compositions (notably the levels of Fe, Al, and Mn). Zn precipitation had a distinct buffering effect at near-neutral pH for the mine waters not dominated by iron. The formation of solid Mg phases (carbonate, as well as hydroxide) was indicated at high pH (above 9), but not formation of solid Ca phases, despite high sulfate levels. The phases that precipitated were various amorphous mixtures, mostly of the metals Fe, Al, Mn, Zn, and Mg. For the Fe-rich mine water, pH was poorly simulated with a simple MIX model, while alkalinity predictions agreed reasonably well with measured data. For the Al-rich mine waters, the simulated pH responses agreed well with the measurements. In an additional step, geochemical simulations were performed where selected proxy phases for major elements were forced to precipitate; this significantly improved the pH and alkalinity predictions. This approach may be more efficient than performing mixing experiments and titrations.
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14. |
- Sartz, Lotta, et al.
(författare)
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Treatment of Acidic and Neutral Metal-Laden Mine Waters with Bone Meal Filters
- 2013
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 32:4, s. 293-301
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Tidskriftsartikel (refereegranskat)abstract
- Bone meal was used to treat two different mine waters: acidic (pH 4.5) mine water containing high concentrations of Fe and Al and neutral/slightly alkaline (pH 7) mine water. Original primary contaminants in both waters were Pb and Zn. The contaminants were dissolved in the acidic mine water and mostly suspended in the neutral mine water. Flow through the filter treating the acidic mine water was relatively low (0.1 L/min), but increased towards the end of the test period. Removal of Pb and Cu was very good in the acidic mine water (around 80 %); removal of Zn was slightly less (60 %) due to the final pH (approximate to 6-6.5). Flow through the filter treating the neutral mine water was initially significantly higher (5 L/min) and the removal of Pb and Zn was less compared to the acidic mine water (50 % for Pb and 35 % for Zn). The major reason for the difference in metal removal in the two mine waters was the difference in Fe and Al sorption sites, flow rate, and pH; in order for the bone meal to dissolve and form metal phosphate, the pH has to be <7.
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15. |
- Thomas, Rimon, et al.
(författare)
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Natural radioactivity and element characterization in pit lakes in Northern Sweden
- 2022
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1025-9112 .- 1616-1068 .- 1932-6203. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Northern Sweden has been the object of intense metal mining in the last decades producing several water-filled open-pits, or pit lakes. Most of these pit lakes have been limed to maintain a good water quality and to prevent generation of acidic water that could leach the exposed rocks and release metals into water. The aim of this work was to examine the concentration of stable elements and naturally occurring radionuclides in water and sediment samples from pit lakes originating from non-uranium mining activities in Northern Sweden. Surface water and surface sediments were collected from 27 pit lakes in Northern Sweden. Water quality parameters, concentration of stable elements and radionuclides were measured by a water probe, ICP-MS and XRF, and alpha and gamma spectrometry, respectively. Furthermore, a multivariate statistical analysis (PCA) was performed on the water samples and sediments. In general, the quality of the surface water was good, but some lakes had low pH values (2.5–5.7), and high concentrations of Fe (up to 200 mg/L) and other metals (e.g. Zn, Cu). When relating the metal concentrations in sediments in pit lakes with the concentration found in natural lakes, some sites had relatively high levels of Cu, As, Cr and Pb. The activity concentration of 210Po, and U and Th isotopes in water and sediment samples were at environmental levels, as was the ambient dose equivalent rate at these sites (range 0.08–0.14 μSv/h).
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17. |
- Westerstrand, Magnus, et al.
(författare)
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Geochemical effects of increased production on recirculated process water at the Kiirunavaara iron mine, Northern Sweden
- 2011
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 30:4, s. 252-262
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Tidskriftsartikel (refereegranskat)abstract
- Understanding process water characteristics and variations is important for ensuring high quality processing of iron ore. Large amounts of water are used during refinement, and the water is often recirculated to save energy. Water quality is important for processes such as flotation and agglomeration but recirculation of process water and changes in production can alter water quality significantly. This study was undertaken to better understand the origin of dissolved components in the process water and water quality variations in process water geochemistry at the Kiirunavaara magnetite ore mine, based on analyses from 1989 to 2008. Long-term trends at single sampling stations in the process chain, as well as changes along the process chain, were studied. Ca, S, Na, and Cl are the major elements in the process water, accounting for over 80% of the dissolved concentration. Ca has the highest concentrations with a mean of 183 mg/L and a maximum of 303 mg/L in the clarifying pond. At all investigated sampling stations (influent water and water in the sorting plant, concentration plant, pelletizing plant, and clarifying pond), dissolved elemental concentrations increased during the studied time period. This increase was mainly caused by increased production. The high concentrations of Ca and S probably result from sulfide oxidation and calcite buffering in the drainage area. The high N concentrations come from undetonated explosives while the main source of Na and Cl is fluid inclusions. If production continues to increase, higher concentrations in the process water should be anticipated.
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18. |
- Åhlgren, Kristina, 1976-, et al.
(författare)
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Chemistry of Acidic and Neutralized Alum Shale Pit Lakes 50 Years After Mine Closure, Kvarntorp, Sweden
- 2020
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Ingår i: Mine Water and the Environment. - : Springer. - 1025-9112 .- 1616-1068. ; 39:3, s. 481-497
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Tidskriftsartikel (refereegranskat)abstract
- Several large pits were left after alum shale was mined from 1942 to 1966 in the Kvarntorp area of Sweden. Of these, the pit lakes Polen and Norrtorpssjon are the focus of this study. They have elevated levels of Na, K, Mg, Ca, Al, Mn, Fe, and sulphate, as well as trace elements, from weathering of the exposed shale. Both lakes had a stable pH below 4 until 1996 when the pH in Norrtorpssjon started to increase, exceeding 8 in 2010, due to inflow of leachates from alkaline waste dumped in an adjacent waste deposit, similar to a large scale anoxic limestone drain (ALD). Iron and Al concentrations decreased as the pH increased, indicating formation of particulate species which accumulate as sediments. The Co, Ni, and Zn concentrations also decreased, probably due to association with the solid phases, while Cu was less affected by the increase in pH, possibly due to formation of complexes with dissolved organic matter. Vanadium concentrations show limited solubility, while Mo concentrations increased at higher pH. Uranium concentrations decreased from above 80 mu g/L to below 10 mu g/L before rising to 30-35 mu g/L due to the formation of soluble carbonate complexes at higher pH levels. The elevated levels of Li, Sr, and U indicate that weathering has continued despite the pH change. Both pit lakes are stratified, but no seasonal overturn has been observed. Long-term behaviour of this large-scale ALD and its implications are also discussed.
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