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Biography [eng]

Green liquor dregs-amended till to cover sulfidic mine waste.

The mining industry produces massive amounts of waste that without treatment and in contact with oxygen can result in acid rock drainage (ARD) and increased leaching of metals. In Sweden, the common way to manage the mine waste after closure is to apply a soil coverage on top of the waste deposition. The purpose of the soil cover is to hinder the oxygen transport to the waste rock underneath. This is achieved by minimizing the water transport to the waster rock and by creating a water saturated layer on top of the waste rock to deter the oxygen diffusion through the air in the pores. The access to a suitable cover-material is however limited and can lead to extensive costs for the mining company. This creates a great driving force for alternative solutions, e.g. bentonite amendment to till. However, bentonite production is costly both economically and environmentally due to time- and resource- consuming production. Recycling of industrial residues as a cover material is another option. The recycling is beneficial for many parts, i.e. the industry producing the residue, the mining industry that will use the residue and the society in its strive for zero waste. An industrial residue that has potential to improve the sealing layer qualities of a local till is Green Liquor Dregs (GLD), a residue from pulp production in a paper mill.

The study can be devided into a laboratory part and a field part. In the laboratory part 5 to 20 wt. % of GLD from different paper mills, were mixed with three tills with varying particle size distributions (PSD) and total solid content (TSC). The objectives of the study were to investigate if GLD addition can improve a till so it can be used in a sealing layer, how the fines- and clay content in the tills affects the hydraulic conductivity (HC) and the water retention capacity (WRC) of the till-GLD mixtures, and how the initial water content will affect the HC in the different mixtures.

In the field part a pilot cell and an experimental surface consiting of till and 10 wt. % GLD has been constructed. the soil cover has been instrumented with oxygen provbes, temperature probes, soil moisture probes and pore pressure probes to evaluate the effectivness of the cover to prohibit oxygen diffusion to the waste rock underneath.

Biography [swe]

Tillsatts av grönlutslam i morän för täckning av sulfidhaltigt gruvavfall.

Gruvindustrin producerar massiva mängder avfall som utan behandling och i kontakt med syre kan resultera i surt lakvatten (ARD) med ökad utlakning av metaller som följd. I Sverige är det vanliga sättet att hantera gruvavfallet efter stängning att applicera en torrtäckning ovanpå gråbergsdeponin. Syftet med torrtäckningen är att förhindra syretillförseln till gråberget under. Detta uppnås dels genom att minimera vattentransporten till gråbeget och att skapa ett vattenmättat lager ovanför gråberget för att därmed förhindra syrediffusionen via luften i porerna. Tillgången till ett lämpligt täckmaterial  är dock begränsat och kan leda till stora kostnader för gruvbolaget. Det skapar en stor drivkraft för alternativa lösningar, där tillsats av bentonit till moränen är ett exempel. Bentonitproduktionen är dock dyr både ekonomiskt och miljömässigt på grund av tids- och resurskrävande produktion. Återvinning av industriella restprodukter som täckmaterial är ett annat alternativ. Återvinningen är fördelaktig för många parter, men framförallt industrin som producerar restprodukten, gruvindustrin som kommer att använda produkten och samhället i sin strävan efter noll-avfall. En industriell restprodukt som har potential att förbättra tätskiktets kvalitet hos en lokal morän är grönlutslam (GLS), en restprodukt från massaproduktionen.

Studien kan delas upp i en laborationsdel och en fältdel. I laborationsdelen av studien tillsattes 5 till 20 viktprocent GLS från olika pappersbruk, till tre morän med varierande partikelstorleksfördelning (PSD) och torrsubstans (TSC). Syftet med laborationstudien var att undersöka om (i) GLS-tillsatsen kan förbättra en morän så att den kan användas i ett tätskikt, (ii) hur silt- och lerinnehållet i moränerna påverkar den hydrauliska konduktiviteten och vattenhållningsförmågan av morän-GLS-blandningarna, och (iii) hur den ursprungliga vattenhalten kommer att påverka den hydrauliska konduktiviteten i de olika blandningarna.

I fältdelen har en pilotcell och en experimentsyta där ett tätskikt av morän och 10 viktprocent GLS har byggts upp. Täckningen har instrumenterats med syresonder, temperatursonder, fuktighetsmätare och portrycksmätare för att utvärdera täckningens effektivitet i att förhindra syrediffusionen till gråberget.

Publications (10 of 18) Show all publications
Nigéus, S., Maurice, C., Lindblom, J. & Josef, M. (2023). Dimensioning and Construction of a Sealing Layer Made of Green Liquor Dregs Amended Till—Remediation of Sulfidic Mine Waste. Mining, Metallurgy & Exploration, 40(6), 2281-2292
Open this publication in new window or tab >>Dimensioning and Construction of a Sealing Layer Made of Green Liquor Dregs Amended Till—Remediation of Sulfidic Mine Waste
2023 (English)In: Mining, Metallurgy & Exploration, ISSN 2524-3462, Vol. 40, no 6, p. 2281-2292Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
Mine waste, ARD, Industrial residues, Green liquor dregs, Field application, Cover system
National Category
Geochemistry Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-102377 (URN)10.1007/s42461-023-00860-9 (DOI)2-s2.0-85178956202 (Scopus ID)
Projects
GLADPaperchain
Funder
Örebro University, 730305EU, Horizon 2020, 730305Mistra - The Swedish Foundation for Strategic Environmental Research, 730305
Note

Validerad;2024;Nivå 2;2024-04-02 (hanlid);

Funder: Boliden Mineral AB; RISE Processum AB;

Full text License: CC BY 4.0

This article has previously appeared as a manuscript in a thesis.

Available from: 2023-11-10 Created: 2023-11-10 Last updated: 2024-04-02Bibliographically approved
Nigéus, S., Maurice, C. & Lindblom, J. (2023). Hydrogeological Properties of Till Amended with Green Liquor Dregs (GLD): Recycling of an Industrial Residue for Reclamation of Acid Generating Mine Sites. Geotechnical and Geological Engineering, 41, 3625-3639
Open this publication in new window or tab >>Hydrogeological Properties of Till Amended with Green Liquor Dregs (GLD): Recycling of an Industrial Residue for Reclamation of Acid Generating Mine Sites
2023 (English)In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 41, p. 3625-3639Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Green liquor dregs, Circular economy, Mine reclamation, Sealing layer, Hydraulic conductivity, Water retention capacity
National Category
Geochemistry
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-97625 (URN)10.1007/s10706-023-02477-7 (DOI)000995722600002 ()2-s2.0-85150399672 (Scopus ID)
Funder
VinnovaSwedish Energy AgencySwedish Research Council FormasEU, Horizon 2020, Nº 730305 (project Paperchain)
Note

Validerad;2023;Nivå 2;2023-07-20 (sofila);

Funder: Boliden Mineral AB

Licens fulltext: CC BY License

Available from: 2023-05-29 Created: 2023-05-29 Last updated: 2023-11-10Bibliographically approved
Nigéus, S., Maurice, C. & Lindblom, J. (2023). Instrumentation of Sealing Layers Made of Two Different Amendments (Green Liquor Dregs and Bentonite) to Till for Reclamation of Sulfidic Mine Waste. Mine Water and the Environment, 42(3), 441-448
Open this publication in new window or tab >>Instrumentation of Sealing Layers Made of Two Different Amendments (Green Liquor Dregs and Bentonite) to Till for Reclamation of Sulfidic Mine Waste
2023 (English)In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 42, no 3, p. 441-448Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer Nature, 2023
Keywords
ARD, Dry cover, Field application, Industrial residues, Monitoring, Reclamation
National Category
Geochemistry Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-101257 (URN)10.1007/s10230-023-00949-z (DOI)001050490600001 ()2-s2.0-85168392670 (Scopus ID)
Funder
EU, Horizon 2020, Paperchain
Note

Validerad;2023;Nivå 2;2023-11-09 (hanlid);

Funder: Boliden Mineral AB; RISE Processum AB;

Full text license: CC BY

Available from: 2023-09-07 Created: 2023-09-07 Last updated: 2023-11-10Bibliographically approved
Nigéus, S. (2023). Recycling of green liquor dregs in cover application on acid generating mine waste. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Recycling of green liquor dregs in cover application on acid generating mine waste
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The mining industry generates massive amounts of waste that without treatment and in contact with atmospheric oxygen can cause the formation of acid rock drainage (ARD). In Sweden, the most common reclamation measure for mine waste is to apply a multi-layer cover on top of the waste deposit. The access to suitable cover-materials is, however, limited and can lead to extensive costs for the mining companies. This creates a driving force for alternative solutions, e.g., bentonite amendment to till. As bentonite production is costly both economically and environmentally, recycling of industrial residues to produce sealing layer material is an attractive option. The recycling is beneficial for the industry generating the residue, the mining industry using the residue and the society in its strive for zero waste. An industrial residue that has potential to improve the sealing properties of local till is green liquor dregs (GLD), a residue from pulp production. The main objective of this study was to, by laboratory studies and field application and evaluations, investigate if green liquor dregs amended till can be used as a sealing layer material on top of acid generating mine waste. The conclusion from the laboratory study is that the hydraulic conductivity does not decrease significantly with GLD addition to the silty till. However, the water retention capacity, which can be seen as the major important feature of a sealing layer to be used on top of sulfidic mine waste by keeping the layer close to saturation, shows significant improvements with GLD addition. In the field study the GLD amended till was applied successfully from a soil mechanical point of view (e.g., the compaction degree after application). The early results from the monitoring of the sealing layer indicate results comparable to the more frequently used bentonite amendment in a sealing layer, with soil moisture values reaching close to saturation. However, this study also concludes that the great variation in GLD, especially regarding its soil mechanical properties such as water content, makes it difficult to use compared to commercial products. The material used in the laboratory investigations in the planning phase of a project might behave differently than the one that is delivered to the minesite for reclamation.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2023
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Other Environmental Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-102378 (URN)978-91-8048-436-7 (ISBN)978-91-8048-437-4 (ISBN)
Public defence
2024-03-12, E632, Luleå tekniska universitet, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2023-11-10 Created: 2023-11-10 Last updated: 2024-03-01Bibliographically approved
Nigéus, S., Maurice, C. & Lindblom, J. (2023). The Drivers of Hydraulic Conductivity in Green Liquor Dregs Amended Till: Application to Reclamation of Acid Generating Mine Sites. Mine Water and the Environment, 42, 59-69
Open this publication in new window or tab >>The Drivers of Hydraulic Conductivity in Green Liquor Dregs Amended Till: Application to Reclamation of Acid Generating Mine Sites
2023 (English)In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 42, p. 59-69Article in journal (Refereed) Published
Abstract [en]

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.

Abstract [es]

La industria minera produce cantidades ingentes de residuos que, en contacto con el oxígeno, pueden dar lugar a la lixiviación de metales. El acceso a un material de recubrimiento adecuado para los residuos mineros es a veces limitado, lo que impulsa el reciclado de residuos industriales para estos fines. Los residuos de licor verde (GLD), un residuo industrial procedente de la producción de papel y pasta de papel, tiene el potencial de utilizarse en una capa de sellado como enmienda al laboreo. Aunque la conductividad hidráulica se utiliza habitualmente para evaluar la calidad de la capa de sellado, la aplicación sobre el terreno a partir de investigaciones de laboratorio es un desafío, ya que muchos factores incluyendo las grandes variaciones en las propiedades físicas tanto del suelo como del GLD, controlan la conductividad hidráulica. En este estudio, 5-20 % en peso de GLD de dos fábricas de papel diferentes, con diferentes contenidos totales de sólidos y distribuciones de tamaño de partículas, se mezclaron con un sedimento limoso con diferentes contenidos totales de sólidos para investigar cómo la densidad seca de los materiales, el contenido inicial de agua y la compactación afectan a la conductividad hidráulica. El contenido inicial de agua de los materiales resultó el factor más importante. Para un sedimento y un GLD más secos, debería añadirse más GLD para alcanzar la menor conductividad hidráulica posible. No se observó que la compactación afectara notablemente a la conductividad hidráulica de las mezclas.

Abstract [zh]

采矿业产生的大量废弃物与氧气接触会导致金属的浸出, 很难获取合适的材料来对采矿废料进行覆盖密封处理, 进而促进了工业废料回收利用工作的进行. 绿液渣 (Green Liquor Dregs, GLD) 是纸浆生产过程中产生的工业废渣, 具有作为冰碛土改良剂来应用到密封层中的潜力. 渗透系数常用来评价密封层的密封程度, 但由于受许多因素控制影响, 要将实验室有关冰碛土和GLD研究的成果在现场应用并不容易, 其中就包含了两者物理性质在实验室和现场会产生巨大的差异. 本研究将来自两个不同造纸厂, 质量百分比在5~20%, 总固体含量和粒径分布不同的GLD, 与不同总固体含量的粉砂状的冰碛土混合, 研究材料的干密度, 初始含水量和压实度对渗透系数的影响. 研究发现渗透系数最重要的影响因素是初始含水量. 冰碛土和GLD混合物越干燥, 要达到尽可能低的渗透系数添加的GLD越多, 而压实度对混合物渗透系数影响并不明显. 

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Industrial residue, Circular economy, Sealing layer, Optimum water content, Compaction effort
National Category
Geochemistry
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-95516 (URN)10.1007/s10230-023-00919-5 (DOI)000925358900001 ()2-s2.0-85147341211 (Scopus ID)
Funder
VinnovaSwedish Energy AgencySwedish Research Council FormasMistra - The Swedish Foundation for Strategic Environmental Research
Note

Validerad;2023;Nivå 2;2023-04-18 (joosat);

Available from: 2023-02-06 Created: 2023-02-06 Last updated: 2023-11-10Bibliographically approved
Nigéus, S., Maurice, C. & Lindblom, J. (2022). Water Retention Capacity as a Measure to Evaluate the Effectiveness of a Green Liquor Dregs-Amended Till to Cover Sulfidic Mine Waste. In: James Pope; Christian Wolkersdorfer; Rachel Rait; Dave Trumm; Hana Christenson; Karoline Wolkersdorfer (Ed.), IMWA 2022 Conference - "Reconnect": Proceedings of the International Mine Water Association Conference. Paper presented at 2022 Conference of the International Mine Water Association (IMWA 2022), November 6-10, 2022, Christchurch, New Zealand (pp. 337-344). International Mine Water Association 2023
Open this publication in new window or tab >>Water Retention Capacity as a Measure to Evaluate the Effectiveness of a Green Liquor Dregs-Amended Till to Cover Sulfidic Mine Waste
2022 (English)In: IMWA 2022 Conference - "Reconnect": Proceedings of the International Mine Water Association Conference / [ed] James Pope; Christian Wolkersdorfer; Rachel Rait; Dave Trumm; Hana Christenson; Karoline Wolkersdorfer, International Mine Water Association 2023 , 2022, p. 337-344Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
International Mine Water Association 2023, 2022
Keywords
Green Liquor Dregs, Sealing layer, Water retention capacity, Industrial residue, Recycling, Circular economy
National Category
Other Earth and Related Environmental Sciences
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-96174 (URN)978-3-9825293-0-1 (ISBN)
Conference
2022 Conference of the International Mine Water Association (IMWA 2022), November 6-10, 2022, Christchurch, New Zealand
Funder
VinnovaSwedish Energy AgencySwedish Research Council FormasEU, Horizon 2020, 730305
Note

Funder: Boliden Mineral AB;

Available from: 2023-03-17 Created: 2023-03-17 Last updated: 2024-02-07Bibliographically approved
Kronsell, I., Nigéus, S., Virolainen, A., Jia, Y., Pabst, T. & Marurice, C. (2020). Amelioration of permeable soil with green liquor dregs for the construction of sealing layers for mine waste storage facilities. In: R. Cardoso, C. Jommi, E. Romero (Ed.), 4th European Conference on Unsaturated Soils (E-UNSAT 2020): . Paper presented at 4th European Conference on Unsaturated Soils (E-UNSAT 2020), 19-21 October, 2020, Lisboa, Portugal. EDP Sciences, Article ID 06006.
Open this publication in new window or tab >>Amelioration of permeable soil with green liquor dregs for the construction of sealing layers for mine waste storage facilities
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2020 (English)In: 4th European Conference on Unsaturated Soils (E-UNSAT 2020) / [ed] R. Cardoso, C. Jommi, E. Romero, EDP Sciences, 2020, article id 06006Conference paper, Published paper (Refereed)
Abstract [en]

Mining of sulfidic ore generates acidic waste which often leads to the generation of acid rock drainage (ARD) having an adverse impact on aquatic flora and fauna. Engineered multilayer cover is one of the commonly used methods to prevent oxygen from being transported to mine waste. The sealing layer has a key function in the cover, thanks to its high water retention capacity and a low hydraulic conductivity, which enable the layer to remain near water saturation, effectively hindering oxygen diffusion. When adequate material is not available improvement of local soil material with a sealing agent is principally the only option to produce sealing layer material. Apart from bentonite clay, Green Liquor Dregs (GLD), a waste from the pulp and paper industry, have the ability to reduce the oxygen diffusion when mixed to granular soil, improving the water retention capacity of the blend. Experience from the development of Till/GLD-blends for the construction of sealing layers is compiled to address issue related to soil amelioration using waste with focus on material variation and quality control. The presentation focuses on the opportunities and challenges for the establishment of a circular system based on reutilization of a waste, herein GLD for improvement of soil’s geotechnical property.

Place, publisher, year, edition, pages
EDP Sciences, 2020
Series
E3S Web of Conferences, E-ISSN 2267-1242 ; 195
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-82775 (URN)10.1051/e3sconf/202019506006 (DOI)000659488200137 ()2-s2.0-85097132804 (Scopus ID)
Conference
4th European Conference on Unsaturated Soils (E-UNSAT 2020), 19-21 October, 2020, Lisboa, Portugal
Funder
Mistra - The Swedish Foundation for Strategic Environmental ResearchEU, Horizon 2020, 730305, H2020-MSCA-RISE-2017, 778120
Available from: 2021-02-04 Created: 2021-02-04 Last updated: 2021-06-30Bibliographically approved
Alakangas, L., Kaasalainen, H., Maurice, C., Nyström, E. & Nigéus, S. (2019). StopOx: Utilization Of Industrial Residuals For Prevention Of Sulfide Oxidation In Mine Waste. Luleå: Luleå University of Technology
Open this publication in new window or tab >>StopOx: Utilization Of Industrial Residuals For Prevention Of Sulfide Oxidation In Mine Waste
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2019 (English)Report (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2019. p. 83
Keywords
mine waste, sulfide oxidation, ARD, inhibition, dry cover, seconday minerals
National Category
Environmental Engineering
Research subject
Applied Geochemistry; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-75754 (URN)978-91-7790-448-9 (ISBN)978-91-7790-449-6 (ISBN)
Funder
Vinnova, 2014-01860
Available from: 2019-08-29 Created: 2019-08-29 Last updated: 2024-04-12Bibliographically approved
Nigéus, S. (2018). Green liquor dregs-amended till to cover sulfidic mine waste. (Licentiate dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Green liquor dregs-amended till to cover sulfidic mine waste
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Alternative title[sv]
Tillsatts av grönlutslam i morän för täckning av sulfidhaltigt gruvavfall
Abstract [en]

The mining industry produces massive amounts of waste that without treatment and in contact with oxygen can result in acid rock drainage (ARD) and increased leaching of metals. In Sweden, the common way to manage the mine waste after closure is to apply a dry coverage on top of the waste deposition. The access to a suitable cover-material is however limited and can lead to extensive costs for the mining company. This creates a great driving force for alternative solutions, e.g. bentonite amendment to till. However, bentonite production is costly both economically and environmentally due to time- and resource- consuming production. Recycling of industrial residues as a cover material is another option. The recycling is beneficial for many parts, i.e. the industry producing the residue, the mining industry that will use the residue and the society in its strive for zero waste. An industrial residue that has potential to improve the sealing layer qualities of a local till is Green Liquor Dregs (GLD), a residue from pulp production in a paper mill. In this study 5 to 20 wt. % of GLD from two different paper mills, with varying total solid content (TSC) and particle size distributions (PSD), were mixed with three tills also with varying PSD and TSC. The objectives of the study were to investigate if GLD addition can improve a till so it can be used in a sealing layer, how the fines- and clay content in the tills affects the hydraulic conductivity (HC) and the water retention capacity (WRC) of the till-GLD mixtures, and how the initial water content will affect the HC in the different mixtures. The HC of the mixtures based most of the tills studied improved, but not enough to reach the required 10-8 m/s. Only the material based on a more clayey silty till had an HC below 10-8 m/s, even if it increased with the addition of GLD. The WRC, on the other hand, shows promising results, especially for 15 wt. % GLD addition. An increase in WRC is seen the more GLD is added. However, due to compaction difficulties more than 20 wt. % addition is not recommended. There is a difference in both HC and WRC between the mixtures based on the different tills, and a characterization of the till as a bulk material and its mixture with GLD is suggested before using it in mine remediation purposes. The HC of the till is affected by the content of fines and especially clay. The results from the WRC is more complicated and a mineralogical study on the GLD and the clay fraction of the tills is recommended. This study also shows that the initial water content of the materials rather than dry density has an impact on the HC of the mixtures. The initial water content determines the degree wet of optimum that in this and previous studies has shown to greatly affect the HC. A drier till and GLD leads to that more GLD should be added to the mixture when reaching for optimal HC. Even if the study did not result in low enough HC in most of the cases, the WRC shows promising results and is the most important parameter minimizing the oxygen diffusion to the mine waste. The greatest challenge when working with GLD is, however, its heterogeneity which makes it difficult to predict how it will behave in a sealing layer. Even though, the recycling of GLD in mine waste remediation should be strived for as it is beneficial for both the industry that provides the residue and the mining company. It is also a great profit for the environment as it minimizes the waste disposed and reduce use of natural resources.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Geotechnical Engineering Environmental Sciences Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-68654 (URN)978-91-7790-144-0 (ISBN)978-91-7790-145-7 (ISBN)
Presentation
2018-09-06, E632, Luleå University of Technology, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-10-29Bibliographically approved
Nigéus, S. & Maurice, C. (2018). Monitoring a field application of a Green Liquor Dregs-till mixture in a sealing layer on top of sulfidic mine waste. In: 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity. Paper presented at 11th ICARD IMWA MWD Conference “Risk to Opportunity” (ICARD 2018), September 10-14, 2018, Pretoria, South Africa. (pp. 57-63).
Open this publication in new window or tab >>Monitoring a field application of a Green Liquor Dregs-till mixture in a sealing layer on top of sulfidic mine waste
2018 (English)In: 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity, 2018, p. 57-63Conference paper, Published paper (Refereed)
Abstract [en]

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.

Keywords
Mine waste, ARD, Industrial residues, Green Liquor Dregs, Field application, Monitoring
National Category
Environmental Engineering
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-71890 (URN)9780620806503 (ISBN)
Conference
11th ICARD IMWA MWD Conference “Risk to Opportunity” (ICARD 2018), September 10-14, 2018, Pretoria, South Africa.
Projects
paperChainGLAD - MISTRA Closing the loop
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2019-01-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1367-7080

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