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A laboratory investigation was conducted to identify principal variables-initial mixing water content, porosity, and binder content- impacting undrained shear strength (qu) of stabilized sulfur-rich silty soil. An equation for predicting qu of stabilized soil was established based on the experimental data. Initially, samples were prepared with soils sample with different initial water and binder contents. Multicem, a binder consisting of a mix of cement and cement kiln dust, was added to the samples. Three different percentages of Multicem were mixed at five different soil water contents to measure qu of stabilized mixtures to understand how water content and porosity levels in the samples affect the performance of the binder and their combined impact on the strength of the samples. The soil-binder mixtures were compacted and subsequently cured in laboratory-controlled environment. The prepared samples were tested in uniaxial compression test apparatus. The results evidenced that binder content and corresponding porosity affect the strength of specimens at an equal water content. The results showed that at equal initial mixing water content, the qu of a sample increased by increasing binder content. Furthermore, it was observed that increase of binder content has a reverse effect on porosity. It was appeared lowering the soil water content, initially increased the strength until an optimum water content. Further lowering water content increased the porosity and consequently decreased qu of samples. Moreover, a ratio of porosity/volumetric binder content was chosen to evaluate the impact of these two variables on strength of samples. This study showed that qu is an exponential function of porosity/binder volumetric content ratio which depends on initial mixing water content of mixtures. It was shown at water content lower than the optimum, results of stabilization are more effective than in soil at higher water contents. Therefore, reducing the water content and ther, Validerad;2024;Nivå 1;2024-08-13 (signyg);Full text license: CC BY 4.0

Purpose: The effect of thin-layer capping with activated biochar on sediment-to-water flux was investigated. For the first time, the diffusion of both polycyclic aromatic hydrocarbons (PAHs) and arsenic (As) were studied simultaneously. The fate of As was investigated, under successive dysoxic and oxic conditions, in order to assess and discuss potential trade-off effects when using biochar as an active sorbent for capping of multi-contaminated sediments. Methods: Sediments from the Bureå bay (Sweden), contaminated with PAH and metal elements including As and Hg, were capped with activated biochar and/or bentonite in simple microcosm test systems in the laboratory. The contaminant transport from sediment through the capping to water body was studied by sampling metals in the water phase above the cap over time, or PAH in a heptane layer over water, at regular time intervals. Results: Consistently with the limited previous studies, reductions were observed (e.g., 60–65% for 15-PAH, 100% for chrysene) in sediment-to-water PAH fluxes upon biochar-based thin-layer capping. However, the most important novel finding revealed ambiguous effects of biochar capping on redox-sensitive elements, in particular As. Under the microcosm conditions of the experiment, where pH was affected by the capping material, biochar treatments favoured As mobility under oxic conditions, directly and/or via effects on Fe speciation. While capping limited the diffusion of As under dysoxic conditions, this also favoured greater As mobility under oxic water conditions compared to no capping. Conclusion: Design and monitoring of capping of PAH contaminated sediments should account for potential negative effects on co-occurring contaminants., Validerad;2024;Nivå 2;2024-04-02 (hanlid);Funder: Research Council of Norway (GBV20200775, GBV20210140);Full text license: CC BY 4.0

A laboratory investigation was conducted to identify principal variables-initial mixing water content, porosity, and binder content- impacting undrained shear strength (qu) of stabilized sulfur-rich silty soil. An equation for predicting qu of stabilized soil was established based on the experimental data. Initially, samples were prepared with soils sample with different initial water and binder contents. Multicem, a binder consisting of a mix of cement and cement kiln dust, was added to the samples. Three different percentages of Multicem were mixed at five different soil water contents to measure qu of stabilized mixtures to understand how water content and porosity levels in the samples affect the performance of the binder and their combined impact on the strength of the samples. The soil-binder mixtures were compacted and subsequently cured in laboratory-controlled environment. The prepared samples were tested in uniaxial compression test apparatus. The results evidenced that binder content and corresponding porosity affect the strength of specimens at an equal water content. The results showed that at equal initial mixing water content, the qu of a sample increased by increasing binder content. Furthermore, it was observed that increase of binder content has a reverse effect on porosity. It was appeared lowering the soil water content, initially increased the strength until an optimum water content. Further lowering water content increased the porosity and consequently decreased qu of samples. Moreover, a ratio of porosity/volumetric binder content was chosen to evaluate the impact of these two variables on strength of samples. This study showed that qu is an exponential function of porosity/binder volumetric content ratio which depends on initial mixing water content of mixtures. It was shown at water content lower than the optimum, results of stabilization are more effective than in soil at higher water contents. Therefore, reducing the water content and ther, Validerad;2024;Nivå 1;2024-08-13 (signyg);Full text license: CC BY 4.0

Purpose: The effect of thin-layer capping with activated biochar on sediment-to-water flux was investigated. For the first time, the diffusion of both polycyclic aromatic hydrocarbons (PAHs) and arsenic (As) were studied simultaneously. The fate of As was investigated, under successive dysoxic and oxic conditions, in order to assess and discuss potential trade-off effects when using biochar as an active sorbent for capping of multi-contaminated sediments. Methods: Sediments from the Bureå bay (Sweden), contaminated with PAH and metal elements including As and Hg, were capped with activated biochar and/or bentonite in simple microcosm test systems in the laboratory. The contaminant transport from sediment through the capping to water body was studied by sampling metals in the water phase above the cap over time, or PAH in a heptane layer over water, at regular time intervals. Results: Consistently with the limited previous studies, reductions were observed (e.g., 60–65% for 15-PAH, 100% for chrysene) in sediment-to-water PAH fluxes upon biochar-based thin-layer capping. However, the most important novel finding revealed ambiguous effects of biochar capping on redox-sensitive elements, in particular As. Under the microcosm conditions of the experiment, where pH was affected by the capping material, biochar treatments favoured As mobility under oxic conditions, directly and/or via effects on Fe speciation. While capping limited the diffusion of As under dysoxic conditions, this also favoured greater As mobility under oxic water conditions compared to no capping. Conclusion: Design and monitoring of capping of PAH contaminated sediments should account for potential negative effects on co-occurring contaminants., Validerad;2024;Nivå 2;2024-04-02 (hanlid);Funder: Research Council of Norway (GBV20200775, GBV20210140);Full text license: CC BY 4.0

Using non-hazardous industrial residues in mine waste remediation is beneficial not only for the mining industry where substantial amounts of the waste generated have potential to produce acid rock drainage and pollute the environment, but also the providing industry, minimizing the waste landfilled. In this study green liquor dregs (GLD), residue from 15 different paper mills were characterized to valorize it as a potential product as a cover material. In another part of the study, one of the GLDs and a local till were characterized to determine the optimal mixture of GLD amended till to be used in a field application at the closed Näsliden Mine in northern Sweden. The study concluded 10% GLD-amended till to be the optimal recipe and was successfully applied at the Näsliden mine waste dump. However, the great variability in the characteristics of GLD creates challenges if it is to be valorized as a product., Validerad;2024;Nivå 2;2024-04-02 (hanlid);Funder: Boliden Mineral AB; RISE Processum AB;Full text License: CC BY 4.0This article has previously appeared as a manuscript in a thesis., GLAD, Paperchain

Using non-hazardous industrial residues in mine waste remediation is beneficial not only for the mining industry where substantial amounts of the waste generated have potential to produce acid rock drainage and pollute the environment, but also the providing industry, minimizing the waste landfilled. In this study green liquor dregs (GLD), residue from 15 different paper mills were characterized to valorize it as a potential product as a cover material. In another part of the study, one of the GLDs and a local till were characterized to determine the optimal mixture of GLD amended till to be used in a field application at the closed Näsliden Mine in northern Sweden. The study concluded 10% GLD-amended till to be the optimal recipe and was successfully applied at the Näsliden mine waste dump. However, the great variability in the characteristics of GLD creates challenges if it is to be valorized as a product., Validerad;2024;Nivå 2;2024-04-02 (hanlid);Funder: Boliden Mineral AB; RISE Processum AB;Full text License: CC BY 4.0This article has previously appeared as a manuscript in a thesis., GLAD, Paperchain

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., Validerad;2023;Nivå 2;2023-11-09 (hanlid);Funder: Boliden Mineral AB; RISE Processum AB;Full text license: CC BY

The oxidation of sulfide minerals in mine wastes is a possible threat to the environment as it might have potential to generate acid rock drainage (ARD). A common method to reduce ARD is to apply a dry cover on the mine waste deposit. Considering the massive amounts of mine waste produced in Sweden (104-million-ton in year 2018) there is a great need for suitable dry cover materials. Using non-hazardous industrial residues in the dry cover would be beneficial for both the mining industry and the providing industry as stricter waste management legislation incentivizes them to develop their waste management strategies. The objective of this study was to investigate if an addition of Green Liquor Dregs (GLD), a residue from pulp production, can decrease the hydraulic conductivity and increase the water retention capacity (WRC) of three different tills, with the purpose of improving the performance of a dry cover material on a mine waste deposit. Another objective was to investigate how the hydraulic conductivity and WRC are affected by the contents of fines and clays in the tills. The study concludes that the water retention capacity of the tills improves with GLD addition, however, the hydraulic conductivity did not decrease enough to reach the in Sweden required < 10−8 m/s. Even though, GLD could still successfully be used in the reclamation of mine sites as the high WRC can be seen as the most important factor in deterring acid rock drainage by keeping the sealing layer close to saturation. This study further indicates that there are other factors than the particle size distribution of the materials that controls the hydraulic conductivity of the mixtures, such as initial water content, dry density, and compaction effort., Validerad;2023;Nivå 2;2023-07-20 (sofila);Funder: Boliden Mineral ABLicens fulltext: CC BY License

In this study, a mixing procedure of sulfur-rich soil and cement-based binder to enhance the soil’s unconfined compressive strength (UCS) was tested in field conditions for geotechnical applications. The focus was to evaluate uniformity of industrial size soil-binder mixture, blended by existing method. This paper outlined sampling strategy and the number of samples needed for a valid uniformity evaluation. Moreover, this study emphasized the difference between field mixing and laboratory mixture preparation by comparing UCS of stabilized soil samples in the field and UCS of corresponding samples mixed and prepared in the laboratory environment. In the field, soil and cement were blended in two to four stages with 5% and 7% cement—the percentages being based on the soil’s dry weight under field conditions. Samples were taken from the field mixtures after each stage. Since the number of samples needed to be representative of mixture characteristics for large-scale mixing is not standardized, this field experiment included two phases. The first phase was dedicated to finding a sampling strategy for a large soil pile along with measuring UCS of collected samples. In the second phase, sample collection was conducted based on the results of sampling strategy from the first phase. In the laboratory, samples with percentages of binder similar to the amount of binder in the field were also prepared. Both field and laboratory samples were prepared using the tapping method in the laboratory for UCS test. Samples were cured under similar conditions for 28 days. The results showed that the uniformity of mixture improved after each additional mixing stage. In addition, while spots with low UCS were observed in the second mixing step, these spots were eliminated in the third mixing step, and results of the UCS tests were comparatively uniform. Moreover, comparison of the samples revealed that the UCS of the laboratory mixture is higher than that of the field mixture. This showed, Validerad;2023;Nivå 2;2023-04-14 (hanlid);Funder: Interreg Botnia-Atlantica program, Sustainable treatment of coastal deposited sulfde soils (STASIS)

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., Validerad;2023;Nivå 2;2023-11-09 (hanlid);Funder: Boliden Mineral AB; RISE Processum AB;Full text license: CC BY

In this study, a mixing procedure of sulfur-rich soil and cement-based binder to enhance the soil’s unconfined compressive strength (UCS) was tested in field conditions for geotechnical applications. The focus was to evaluate uniformity of industrial size soil-binder mixture, blended by existing method. This paper outlined sampling strategy and the number of samples needed for a valid uniformity evaluation. Moreover, this study emphasized the difference between field mixing and laboratory mixture preparation by comparing UCS of stabilized soil samples in the field and UCS of corresponding samples mixed and prepared in the laboratory environment. In the field, soil and cement were blended in two to four stages with 5% and 7% cement—the percentages being based on the soil’s dry weight under field conditions. Samples were taken from the field mixtures after each stage. Since the number of samples needed to be representative of mixture characteristics for large-scale mixing is not standardized, this field experiment included two phases. The first phase was dedicated to finding a sampling strategy for a large soil pile along with measuring UCS of collected samples. In the second phase, sample collection was conducted based on the results of sampling strategy from the first phase. In the laboratory, samples with percentages of binder similar to the amount of binder in the field were also prepared. Both field and laboratory samples were prepared using the tapping method in the laboratory for UCS test. Samples were cured under similar conditions for 28 days. The results showed that the uniformity of mixture improved after each additional mixing stage. In addition, while spots with low UCS were observed in the second mixing step, these spots were eliminated in the third mixing step, and results of the UCS tests were comparatively uniform. Moreover, comparison of the samples revealed that the UCS of the laboratory mixture is higher than that of the field mixture. This showed, Validerad;2023;Nivå 2;2023-04-14 (hanlid);Funder: Interreg Botnia-Atlantica program, Sustainable treatment of coastal deposited sulfde soils (STASIS)

The oxidation of sulfide minerals in mine wastes is a possible threat to the environment as it might have potential to generate acid rock drainage (ARD). A common method to reduce ARD is to apply a dry cover on the mine waste deposit. Considering the massive amounts of mine waste produced in Sweden (104-million-ton in year 2018) there is a great need for suitable dry cover materials. Using non-hazardous industrial residues in the dry cover would be beneficial for both the mining industry and the providing industry as stricter waste management legislation incentivizes them to develop their waste management strategies. The objective of this study was to investigate if an addition of Green Liquor Dregs (GLD), a residue from pulp production, can decrease the hydraulic conductivity and increase the water retention capacity (WRC) of three different tills, with the purpose of improving the performance of a dry cover material on a mine waste deposit. Another objective was to investigate how the hydraulic conductivity and WRC are affected by the contents of fines and clays in the tills. The study concludes that the water retention capacity of the tills improves with GLD addition, however, the hydraulic conductivity did not decrease enough to reach the in Sweden required < 10−8 m/s. Even though, GLD could still successfully be used in the reclamation of mine sites as the high WRC can be seen as the most important factor in deterring acid rock drainage by keeping the sealing layer close to saturation. This study further indicates that there are other factors than the particle size distribution of the materials that controls the hydraulic conductivity of the mixtures, such as initial water content, dry density, and compaction effort., Validerad;2023;Nivå 2;2023-07-20 (sofila);Funder: Boliden Mineral ABLicens fulltext: CC BY License

Hydraulic conductivity is often used as a measure to evaluate the effectiveness of a sealing layer material on top of mine waste. However, the most important soil parameter minimizing the oxygen diffusion to the mine waste is the water retention capacity (WRC) of the sealing layer, as a high saturation corresponds to a low oxygen diffusion rate. This study shows that an amendment of Green Liquor Dregs (GLD), an industrial residue, to a till increases its WRC and has therefore potential to be a more accurate method to evaluate the effectiveness of a sealing layer than hydraulic conductivity., Funder: Boliden Mineral AB

Hydraulic conductivity is often used as a measure to evaluate the effectiveness of a sealing layer material on top of mine waste. However, the most important soil parameter minimizing the oxygen diffusion to the mine waste is the water retention capacity (WRC) of the sealing layer, as a high saturation corresponds to a low oxygen diffusion rate. This study shows that an amendment of Green Liquor Dregs (GLD), an industrial residue, to a till increases its WRC and has therefore potential to be a more accurate method to evaluate the effectiveness of a sealing layer than hydraulic conductivity., Funder: Boliden Mineral AB

Cover systems can efficiently limit acid mine drainage generation from sulfidic mine wastes by controlling oxygen diffusion. Their performance relies on their high degree of saturation, as oxygen diffusion is substantially reduced in water or saturated medium. However, natural soils available in the mine vicinities do not necessarily have the hydrogeological properties required for the construction of sealing layers. A common strategy is to improve the characteristics of local soils using bentonite amendment, but this usually induces high costs and environmental footprint. An alternative is to reuse (or valorise) waste materials, such as mine wastes or industrial wastes like green liquor dregs (GLD). Blends of till and GLD can have advantageous properties regarding water retention capacity and hydraulic conductivity. In this study, the effective oxygen diffusion coefficient De of till-GLD blends was evaluated using 81 diffusion tests. Various quantities and different types of GLD were tested. The diffusion coefficient was found to vary greatly depending on the degree of saturation. Even though the GLD contained naturally a substantial amount of water, a high water content of the till was still required to reach a low De. Measurements were also compared with modified Millington-Shearer predictive model which could generally predict the diffusion coefficient within an acceptable range. Results also indicated that the till-GLD mixes should not be exposed to evaporation as significant performance loss may rapidly occur upon drying. Main experimental results are presented in this paper together with recommendations in terms of cover design using till-GLD mixes.

This report is the outcome of the SIP STRIM project StopOx-Utilization of industrial residuals for prevention of sulfide oxidation in mine waste implemented at Applied geochemistry, Luleå University of Technology running from 2015 to 2018. Boliden Mineral has been partner and co-funder of the project. Other partners in the project were Cementa, Dragon Mining, MEROX, Nordkalk, and SP Processum. The overall aim of the project was to develop prevention technologies to reduce the sulfide oxidation in mine waste, during and after operation, and thereby reduce the generation of acid mine drainage. The StopOx project has been focusing on sulfidic mine waste from the Boliden area which were disposed of and are causing acid mine drainage or have the potential. Industrial residues/products were supplied by BillerudKorsnäs, Cementa, MEROX, and Nordkalk. The report consists of chapters based on three subprojects. Chapter 1. Introduction Chapter 2. Inhibition technology with aim to minimize waste rock oxidation during operations by using residues from other industries (passivation of sulfidic surfaces by the formation of secondary minerals) Chapter 3. The suitability of green liquor dregs as substitutes for or additives to till in a sealing layer as part of a cover system Chapter 4. Weathering of waste rock under changing chemical conditions The research described in chapters 2 and 3 was performed by Ph.D. students and will continue until 2021, while the subproject in chapter 2 ended in 2018.

This report is the outcome of the SIP STRIM project StopOx-Utilization of industrial residuals for prevention of sulfide oxidation in mine waste implemented at Applied geochemistry, Luleå University of Technology running from 2015 to 2018. Boliden Mineral has been partner and co-funder of the project. Other partners in the project were Cementa, Dragon Mining, MEROX, Nordkalk, and SP Processum. The overall aim of the project was to develop prevention technologies to reduce the sulfide oxidation in mine waste, during and after operation, and thereby reduce the generation of acid mine drainage. The StopOx project has been focusing on sulfidic mine waste from the Boliden area which were disposed of and are causing acid mine drainage or have the potential. Industrial residues/products were supplied by BillerudKorsnäs, Cementa, MEROX, and Nordkalk. The report consists of chapters based on three subprojects. Chapter 1. Introduction Chapter 2. Inhibition technology with aim to minimize waste rock oxidation during operations by using residues from other industries (passivation of sulfidic surfaces by the formation of secondary minerals) Chapter 3. The suitability of green liquor dregs as substitutes for or additives to till in a sealing layer as part of a cover system Chapter 4. Weathering of waste rock under changing chemical conditions The research described in chapters 2 and 3 was performed by Ph.D. students and will continue until 2021, while the subproject in chapter 2 ended in 2018.

Sul dic mine waste le unattended and in contact with oxygen oxidize and have potential to produce acid rock drainage (ARD). A typical method in Sweden to stop sul de oxidation is to apply a dry cover on top of the mine waste. Using the non-hazardous industrial residue Green Liquor Dregs (GLD) in the cover is useful for the mining industry and the industry providing the residue and a large bene t for the environment. In this study, the e ectiveness of a mixture of till and 10 wt. % of GLD in a dry cover was studied by monitoring temperature, oxygen- and moisture content. e conclusion is that the sealing layer in una ected by frost, the oxygen concentrations are decreasing with time, but not in depth and the sealing layer with GLD-till mixture seem to be nearly saturated., paperChain, GLAD - MISTRA Closing the loop

Sul dic mine waste le unattended and in contact with oxygen oxidize and have potential to produce acid rock drainage (ARD). A typical method in Sweden to stop sul de oxidation is to apply a dry cover on top of the mine waste. Using the non-hazardous industrial residue Green Liquor Dregs (GLD) in the cover is useful for the mining industry and the industry providing the residue and a large bene t for the environment. In this study, the e ectiveness of a mixture of till and 10 wt. % of GLD in a dry cover was studied by monitoring temperature, oxygen- and moisture content. e conclusion is that the sealing layer in una ected by frost, the oxygen concentrations are decreasing with time, but not in depth and the sealing layer with GLD-till mixture seem to be nearly saturated., paperChain, GLAD - MISTRA Closing the loop

Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

Mining has been and still is an important industry in Sweden. Leaching from sulfidic mining waste is however a serious environmental issue that can bring acidity and metals in solution. Simultaneously, green liquor dreg (GLD) with potential to decrease oxygen transport to the waste and neutralize acid leachate, is generated by the pulp and paper industry and deposited in landfills. The aim of the project is to promote valorisation of GLD, identify hinders and create a database providing information about the material and its variability to enhance establishment of circular economy for the pulp and paper mill waste.

Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing tailings as a full-scale remediation approach. The performance and effectiveness of the sealing layers with high water content for an oxygen barrier and low hydraulic conductivity for a sealing layer in preventing the formation of acid rock drainage were evaluated 5 years after the remediation. The leaching behavior of the covered tailings was studied using batch leaching tests (L/S ratio 10 L/kg). The leaching results revealed that, in general, the dregs- and ash-covered tailings released relatively lower concentrations of many elements contained in acid rock drainage compared to those from the uncovered tailings. A change in the chemical composition and mineralogical state of the tailings was observed for the tailings beneath the covers. The increase in pH caused by the alkaline materials promoted metal precipitation. Geochemical modeling using PHREEQC confirmed most of the geochemical changes of the covered tailings. Both the ash and dregs showed potential to function as sealing materials in terms of their geochemical properties. However, mobilization of Zn and Ni from the lower part of the dregs-covered tailings was observed. The same phenomenon was observed for the lower part of the ash-covered tailings. Ash showed advantages over dregs as a cover material; based on geochemical studies, the ash immobilized more elements than the dregs did. Lysimeters were installed below the sealing layers, and infiltrating water chemistry and hydrology were studied to monitor the amount and quality of the leachate percolating through., Funding Agencies:European Union Structural Funds Northern Sweden Soil Remediation Center, EDF Objective 2 (Contract MCN IO) 43173 Sveriges Ingenjör Environmental Fund Center of Advanced Mining and Metallurgy (CAMM)

Godkänd; 2015; 20160525 (sussir), Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes

Godkänd; 2015; 20160525 (sussir), Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes

Godkänd; 2014; 20140416 (andbra), Användning av restprodukter för förhindrande sulfid oxidation i reaktivt gruvavfall - en förstudie

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., Validerad; 2014; 20140424 (makmar)

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., Validerad; 2014; 20140424 (makmar)

Godkänd; 2014; 20140416 (andbra), Användning av restprodukter för förhindrande sulfid oxidation i reaktivt gruvavfall - en förstudie

This study focuses on the effect of green liquor dregs (GLD) and fly ash (FA) on geotechnical stabilization of tailings, using shear strength test.The objectives were to evaluate thickening of tailings using GLD to paste to improve its water retention and to reduce waste percolation, to identify optimal proportion of additives regarding geotechnical stabilization of tailings, and to study the role of FA in the decrease of porosity and thus to reduce oxygen diffusion via hardening process.The results showed that GLD is a potential material for tailings stabilization by decreasing water percolation and improving water retention property. However, the paste of GLD amended tailings withstands low shear strength. The addition of FA to the paste greatly improves shear strength which is up to 2-3 times higher. Moreover, the fly ash hardening process effectively reinforces the strength of GLD amended tailings paste. Longer curing period (3 months) for specimens leads to up to 2-3 folds higher strength compared to that of 1 month. Hydraulic conductivity is reduced as a result of GLD and FA addition, since the porosity of the tailings decreased. If reduced porosity, improved water retention capacity and no cracks are ensured in the tailings, oxygen diffusion can be limited., Godkänd; 2012; 20120608 (yuojia)

Green liquor dregs (GLD) are the largest waste fraction retrieved at the sulphate pulp mill. GLD has a low hydraulic conductivity and is alkaline which opens the possibility of using it for construction of sealing layers. Two sites have been sampled where the GLD age is known. The effect of aging on the material properties specifically the ability to function as a barrier against oxygen and its capacity to buffer in the long term was studied. The mechanical strength has also been evaluated to asses if it can withstand the pressures from the cover layer. Suction tests showed that the capillarity forces in GLD bind water strongly to the particles preventing it from drying. The high water content in GLD and the strength of the water bounding are major advantages for the use in sealing layers to create a water saturated layer preventing oxygen penetration. GLD is therefore believed to be an excellent barrier material in the sealing layer. The GLD’s buffering capacity is high and the results indicate that it will last for a long time which is consistent with its large reservoir of lime. The shear strength increased when the GLD is placed in field conditions., Godkänd; 2012; 20120608 (ysko)

This study focuses on the effect of green liquor dregs (GLD) and fly ash (FA) on geotechnical stabilization of tailings, using shear strength test.The objectives were to evaluate thickening of tailings using GLD to paste to improve its water retention and to reduce waste percolation, to identify optimal proportion of additives regarding geotechnical stabilization of tailings, and to study the role of FA in the decrease of porosity and thus to reduce oxygen diffusion via hardening process.The results showed that GLD is a potential material for tailings stabilization by decreasing water percolation and improving water retention property. However, the paste of GLD amended tailings withstands low shear strength. The addition of FA to the paste greatly improves shear strength which is up to 2-3 times higher. Moreover, the fly ash hardening process effectively reinforces the strength of GLD amended tailings paste. Longer curing period (3 months) for specimens leads to up to 2-3 folds higher strength compared to that of 1 month. Hydraulic conductivity is reduced as a result of GLD and FA addition, since the porosity of the tailings decreased. If reduced porosity, improved water retention capacity and no cracks are ensured in the tailings, oxygen diffusion can be limited., Godkänd; 2012; 20120608 (yuojia)

Green liquor dregs (GLD) are the largest waste fraction retrieved at the sulphate pulp mill. GLD has a low hydraulic conductivity and is alkaline which opens the possibility of using it for construction of sealing layers. Two sites have been sampled where the GLD age is known. The effect of aging on the material properties specifically the ability to function as a barrier against oxygen and its capacity to buffer in the long term was studied. The mechanical strength has also been evaluated to asses if it can withstand the pressures from the cover layer. Suction tests showed that the capillarity forces in GLD bind water strongly to the particles preventing it from drying. The high water content in GLD and the strength of the water bounding are major advantages for the use in sealing layers to create a water saturated layer preventing oxygen penetration. GLD is therefore believed to be an excellent barrier material in the sealing layer. The GLD’s buffering capacity is high and the results indicate that it will last for a long time which is consistent with its large reservoir of lime. The shear strength increased when the GLD is placed in field conditions., Godkänd; 2012; 20120608 (ysko)

Sibelius repeatedly maintained that tempo fluctuations in his music ought to be barely perceptible. Dealing with the subtle tempo modulations in the one-movement Seventh Symphony is thus not surprisingly one of the most challenging aspects of performing the piece. The present study addresses the matters of time and tempo from a variety of perspectives: harmony, compositional process, metronome markings. Throughout, the piece reveals itself as an organism evolving through and in time. First, we look at ways in which harmonic interruptions and sonic echoes are used to create at once continuity and discontinuity in the musical narrative. Borrowing terms from literary studies, we examine the importance of aposiopesis and stylems (a term whose use is owed to Antonin Servière) in the symphony. Each of these forms of interruption exerts a contrary force on the forward thrust of the piece that affects one's experience of time. Second, we examine Sibelius's compositional process by looking at the evolution of the piece from sketch to final form. This analysis reveals the composer stripping away cadences, strategically inserting pedal points, shifting tempo markings to avoid structural downbeats, all to achieve an elasticity and fluidity of time where the perception of tempo changes is blurred. Third, we look at Sibelius's metronome markings. While they contain helpful information, they also withhold information, particularly about the first 93 bars of the piece. We take stock of what this absence reveals about the structure of the piece and about problems in performance related to time and tempo. The ending of the piece receives separate treatment as it is particularly revelatory of Sibelius's compositional process. Here, what the composer discarded sheds light on the enigmatic but highly poetic final version of the ending of the piece. Finally, we offer in the appendix a performance history of the Seventh Symphony. The difficulty of programming this concise but epic work ac

Purpose Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20A degrees C, 30A degrees C and 40A degrees C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions For all extractants, mobilisation was most efficient at elevated temperature (40A degrees C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in, QC 20111228

Sluttäckning av deponier utförs i syfte att minimera inläckage av vatten och syre till avfallet. Principen är att ”det som inte läcker in inte heller kan rinna ut”. Förutom vattentransport ska sluttäckningen bidra till att minimera utläckage av metan som bildas i deponier med organiskt avfall. Sluttäckningen ska dessutom utformas så att den ska fungera under hundratals år. Skyddsskiktets frysmotstånd är en viktig funktion som kan påverka sluttäckningskonstruktionens funktion och livslängd. Trots detta läggs idag relativt lite fokus på hur den utformas med avseende på tjäle och metanoxidation. Traditionellt består sluttäckningens skyddsskikt av en sandwichkonstruktion som inkluderar ett skydds- och växtetableringsskikt. Med genomtänkt materialval kan skyddsskiktet utformas så att det med god marginal kan skydda tätskiktet från tjäle. Målsättningen med projektet är att visa att alternativa material kan fylla en viktig funktion i skyddsskiktet med avseende på metanoxidation och frysmotstånd. I projektet jämförs konventionellt skyddsskikt bestående av morän med skyddsskikt där morän kombineras med alternativa material. Olika materials värmeledningsförmåga togs fram baserat på litteraturstudier och tidigare erfarenheter. Modellering av frysmotstånd utfördes för fem befintliga deponiers skyddsskikt. Frysmotståndet jämfördes sedan med skyddsskikt som består av morän. En moräntäckning (finjordshalt < 30 %) på 1,2 m ger inte tillräckligt frysmotstånd vid en köldmängd på ca 600°dygn. Medelköldmängd 600°dygn i ett 30-årsperspektivpå motsvarar en linje mellan Karlstad och Gävle. Genom att ersätta 0,5 m morän med kompostjord, klarar skyddsskiktet drygt 2400°dygn även om moränkvaliteten inte uppfyller kriteriet på finjordshalt på > 30 % För att uppskatta gasförlusterna genom täckskiktet samlades information om mängd deponerat avfall, uppsamling av deponigas, nedbrytningshastighet och gasbildningspotential från några deponier. Baserat på sammanställningen och en utförd litteraturs, Godkänd; 2011; 20111220 (tomede)

Sluttäckning av deponier utförs i syfte att minimera inläckage av vatten och syre till avfallet. Principen är att ”det som inte läcker in inte heller kan rinna ut”. Förutom vattentransport ska sluttäckningen bidra till att minimera utläckage av metan som bildas i deponier med organiskt avfall. Sluttäckningen ska dessutom utformas så att den ska fungera under hundratals år. Skyddsskiktets frysmotstånd är en viktig funktion som kan påverka sluttäckningskonstruktionens funktion och livslängd. Trots detta läggs idag relativt lite fokus på hur den utformas med avseende på tjäle och metanoxidation. Traditionellt består sluttäckningens skyddsskikt av en sandwichkonstruktion som inkluderar ett skydds- och växtetableringsskikt. Med genomtänkt materialval kan skyddsskiktet utformas så att det med god marginal kan skydda tätskiktet från tjäle. Målsättningen med projektet är att visa att alternativa material kan fylla en viktig funktion i skyddsskiktet med avseende på metanoxidation och frysmotstånd. I projektet jämförs konventionellt skyddsskikt bestående av morän med skyddsskikt där morän kombineras med alternativa material. Olika materials värmeledningsförmåga togs fram baserat på litteraturstudier och tidigare erfarenheter. Modellering av frysmotstånd utfördes för fem befintliga deponiers skyddsskikt. Frysmotståndet jämfördes sedan med skyddsskikt som består av morän. En moräntäckning (finjordshalt < 30 %) på 1,2 m ger inte tillräckligt frysmotstånd vid en köldmängd på ca 600°dygn. Medelköldmängd 600°dygn i ett 30-årsperspektivpå motsvarar en linje mellan Karlstad och Gävle. Genom att ersätta 0,5 m morän med kompostjord, klarar skyddsskiktet drygt 2400°dygn även om moränkvaliteten inte uppfyller kriteriet på finjordshalt på > 30 % För att uppskatta gasförlusterna genom täckskiktet samlades information om mängd deponerat avfall, uppsamling av deponigas, nedbrytningshastighet och gasbildningspotential från några deponier. Baserat på sammanställningen och en utförd litte, Godkänd; 2011; 20111220 (tomede)

Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only similar to 50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH center dot HCl, or citrate were not efficient in mobilizing As from the soils., QC 20110113

In an adaptive sampling strategy based on multi-stage sampling, information gathered in earlier stages is used to choose what information to search for in the next stage. This should be the information that has the greatest probability to best improve the basis for the decisions to be made. Based on literature this paper discusses how to use this strategy to improve investigations of contaminated soil by assessing decision uncertainty. The measurement error, the number of samples and choice of interpolation method are among the factors that have large effect on the usability of the outcome of a multi-stage sampling investigation using interpolation. In the light of increased usage of field-portable test instruments the interaction of measurement error and number of samples needs to be further investigated. Other issues that need attention are how to measure the quality of the basis for decision and how to decide when the quality is good enough., Godkänd; 2010; Bibliografisk uppgift: 1 CD-ROM; 20130102 (andbra)

In an adaptive sampling strategy based on multi-stage sampling, information gathered in earlier stages is used to choose what information to search for in the next stage. This should be the information that has the greatest probability to best improve the basis for the decisions to be made. Based on literature this paper discusses how to use this strategy to improve investigations of contaminated soil by assessing decision uncertainty. The measurement error, the number of samples and choice of interpolation method are among the factors that have large effect on the usability of the outcome of a multi-stage sampling investigation using interpolation. In the light of increased usage of field-portable test instruments the interaction of measurement error and number of samples needs to be further investigated. Other issues that need attention are how to measure the quality of the basis for decision and how to decide when the quality is good enough., Godkänd; 2010; Bibliografisk uppgift: 1 CD-ROM; 20130102 (andbra)

The impact of water saturation level (oxidizing-reducing environment) on As and metal solubility in chromium, copper, arsenic (CCA)-contaminated soil amended with Fe-containing materials was studied. The soil was mixed with 0.1 and 1 wt% of iron grit (Fe(0)) and 1, 7 and 15 wt% of oxygen scarfing granulate (OSG, a by-product of steel processing). Solubility of As and metals was evaluated by a batch leaching test and analysis of soil pore water. Soil saturation with water greatly increased As solubility in the untreated as well as in the Fe-amended soil. This was related to the reductive dissolution of Fe oxides and increased concentration of As(III) species. Fe amendments showed As reducing capacity under both oxic and anoxic conditions. The cytotoxicity of the soil pore water correlated with the concentration of As(III). The Fe-treatments as well as water saturation of soil were less significant for the solubility of Cu, Cr and Zn than for As. The batch leaching test used for waste characterization substantially underestimated As solubility that could occur under water-saturated (anaerobic) conditions. In the case of soil landfilling, other techniques than Fe-stabilization of As containing soil should be considered.

Godkänd; 2009; 20091007 (ysko)

Godkänd; 2009; 20090824 (chma)

Leaching tests have become popular tools to assess the environmental effect of materials containing pollutants e.g. wastes, construction materials, soils. Batch (EN 12457-3) and column (prEN 14405) leaching tests are both standardised. The standardisation regulates how the test should be performed i.e. the procedure, the amount of material to be used and how to handle the leachate. However, standardisation is often misinterpreted as quality insurance that the results of the test are relevant for any type of material and application. The EN 12457-3 test has thanks to the standardisation and its relatively low price become the most popular tests used to assess if waste material could be used in constructions. Basically waste materials fulfilling acceptance criteria for landfill for inert waste are often regarded as acceptable to reuse in the society.The aim of the presentation is to discuss the risk of using tests without a critical assessment of their relevance and limitations. Materials containing sulphides, iron and arsenic are specially challenging to assess as the standard batch leaching test underestimates the risk for leaching.The leaching of arsenic was underestimated by the EN 12457-3 test and the effect of open filtration, sample preparation and test conditions are discussed. The results showed that a material fulfilling criteria for landfill for inert waste leached more arsenic than was acceptable at a landfill for hazardous waste. In the second example, the documented generation of acidic leachate from blast furnace slag in field conditions has never been observed in the laboratory. The main hypothesis is that the development of unsaturated conditions caused the oxidation of sulphidic minerals in the blast furnace slag heap and generation of acid leachate.The selection of appropriate leaching tests should be done with regard to the real conditions that are to be assessed. Standardisation does not mean that the test is automatically adapted to the need. A r, Godkänd; 2009; Bibliografisk uppgift: Værtspublikationsredaktører: Jacques Mehu; 20090824 (chma)

Godkänd; 2009; 20091007 (ysko)

Godkänd; 2009; 20090824 (chma)

Leaching tests have become popular tools to assess the environmental effect of materials containing pollutants e.g. wastes, construction materials, soils. Batch (EN 12457-3) and column (prEN 14405) leaching tests are both standardised. The standardisation regulates how the test should be performed i.e. the procedure, the amount of material to be used and how to handle the leachate. However, standardisation is often misinterpreted as quality insurance that the results of the test are relevant for any type of material and application. The EN 12457-3 test has thanks to the standardisation and its relatively low price become the most popular tests used to assess if waste material could be used in constructions. Basically waste materials fulfilling acceptance criteria for landfill for inert waste are often regarded as acceptable to reuse in the society.The aim of the presentation is to discuss the risk of using tests without a critical assessment of their relevance and limitations. Materials containing sulphides, iron and arsenic are specially challenging to assess as the standard batch leaching test underestimates the risk for leaching.The leaching of arsenic was underestimated by the EN 12457-3 test and the effect of open filtration, sample preparation and test conditions are discussed. The results showed that a material fulfilling criteria for landfill for inert waste leached more arsenic than was acceptable at a landfill for hazardous waste. In the second example, the documented generation of acidic leachate from blast furnace slag in field conditions has never been observed in the laboratory. The main hypothesis is that the development of unsaturated conditions caused the oxidation of sulphidic minerals in the blast furnace slag heap and generation of acid leachate.The selection of appropriate leaching tests should be done with regard to the real conditions that are to be assessed. Standardisation does not mean that the test is automatically adapted to the need. A r, Godkänd; 2009; Bibliografisk uppgift: Værtspublikationsredaktører: Jacques Mehu; 20090824 (chma)

Investigations of polluted brownfield sites and sample analyses are expensive, and the resulting data are often of poor quality. Efforts are needed, therefore, to improve the methods used in investigations of brownfield sites to both reduce costs and improve the quality of the results. One approach that could be useful for both of these purposes is the triad strategy, developed by the US Environmental Protection Agency, in which managing uncertainty is a central feature. In the investigations reported here, a field study was conducted to identify possible ways in which uncertainties could be managed in practice. One example considered involves optimizing the uncertainty by adjusting the sizes of samples and the efforts expended in analytical work according to the specific aims of the project. In addition, the potential utility of several toxicity assessment methods for screening sites was evaluated. As well as presenting the results of these assessments, in this contribution we discuss ways in which a flexible work strategy and screening methods inspired of the triad philosophy could be incorporated into the Swedish approach to remediate brownfield sites. A tiered approach taking advantage of field and screening methods is proposed to assess brownfield sites focusing on the response and acceptable uncertainty that are required for the task., Validerad; 2007; 20071010 (chma)