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Nyström, E., Kaasalainen, H. & Alakangas, L. (2019). Prevention of sulfide oxidation in waste rock by the addition of lime kiln dust. Environmental Science and Pollution Research
Open this publication in new window or tab >>Prevention of sulfide oxidation in waste rock by the addition of lime kiln dust
2019 (English)In: Environmental Science and Pollution Research, ISSN 0944-1344Article in journal (Refereed) Epub ahead of print
Abstract [en]

During the operation of a mine, waste rock is often deposited in heaps and usually left under ambient conditions allowing sulfides to oxidize. To focus on waste rock management for preventing acid rock drainage (ARD) formation rather than ARD treatment could avoid its generation and reduce lime consumption, costs, and sludge treatment. Leachates from 10 L laboratory test cells containing sulfide-rich (> 60% pyrite) waste rock with and without the addition of lime kiln dust (LKD) (5 wt.%) were compared to each other to evaluate the LKD’s ability to maintain near neutral pH and reduce the sulfide oxidation. Leaching of solely waste rock generated an acidic leachate (pH < 1.3) with high concentrations of As (21 mg/L), Cu (20 mg/L), Fe (18 g/L), Mn (45 mg/L), Pb (856 μg/L), Sb (967 μg/L), S (17 g/L), and Zn (23 mg/L). Conversely, the addition of 5 wt.% LKD generated and maintained a near neutral pH along with decreasing of metal and metalloid concentrations by more than 99.9%. Decreased concentrations were most pronounced for As, Cu, Pb, and Zn while S was relatively high (100 mg/L) but decreasing throughout the time of leaching. The results from sequential extraction combined with element release, geochemical calculations, and Raman analysis suggest that S concentrations decreased due to decreasing sulfide oxidation rate, which led to gypsum dissolution. The result from this study shows that a limited amount of LKD, corresponding to 4% of the net neutralizing potential of the waste rock, can prevent the acceleration of sulfide oxidation and subsequent release of sulfate, metals, and metalloids but the quantity and long-term stability of secondary minerals formed needs to be evaluated and understood before this method can be applied at a larger scale.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Preventive measures, Acid rock drainage, Sulfidic waste rock, Sulfide oxidation, Waste rock management, Neutralization, By-products, Lime kiln dust
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-75275 (URN)10.1007/s11356-019-05846-z (DOI)31273653 (PubMedID)
Available from: 2019-07-10 Created: 2019-07-10 Last updated: 2019-08-05
Nyström, E., Kaasalainen, H. & Alakangas, L. (2019). Suitability study of secondary raw materials for prevention of acid rock drainage generation from waste rock. Journal of Cleaner Production, 232, 575-586
Open this publication in new window or tab >>Suitability study of secondary raw materials for prevention of acid rock drainage generation from waste rock
2019 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 232, p. 575-586Article in journal (Refereed) Published
Abstract [en]

Prevention and mitigation of acid rock drainage (ARD) from mine wastes are crucial for limiting environmental impact. However, preventive measures are often too expensive, potentially harmful to the environment or not applied early enough. This study aimed to test the potential of different secondary raw materials for maintaining a circumneutral pH (6–7) in a sulfide oxidation environment, allowing secondary minerals to form on reactive sulfide surfaces to prevent release of acid, metals and metalloids, and thereby ARD generation. Five materials (blast furnace slag, granulated blast furnace slag, cement kiln dust, bark ash, lime kiln dust) were selected based on their alkaline properties, availability and yearly yield. High sulfidic (>50 wt%, sulfide) waste rock from an active Cu–Zn–Au–Ag open pit mine in northern Sweden was leached in small-scale laboratory test cells under ambient condition for 4–8 weeks before adding secondary raw materials on the surface in an attempt to prevent ARD generation. During 52 subsequent weeks of leaching, the pH and electrical conductivity in the leachate from the waste rock varied between 1.7-4.6 and 2.1–22.8 mS/cm, respectively. All secondary raw materials were able to increase the pH to circumneutral. However, blast furnace slag, granulated blast furnace slag and cement kiln dust were not able to maintain a circumneutral pH for an extended time due to self-cementation or carbonation, whereas bark ash (1 wt%) and lime kiln dust (5 wt%) prevented acidity, metal and metalloid leaching. Materials such as cement kiln dust and bark ash contained elevated concentrations of, e.g., Cd and Zn, but the release of metals and metalloids was generally low for most elements, except for Cl, K and Na, most likely due to salt dissolution.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-74010 (URN)10.1016/j.jclepro.2019.05.130 (DOI)2-s2.0-85066824424 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-17 (svasva)

Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-27Bibliographically approved
Nyström, E. (2018). Suitability of industrial residues for preventing acid rock drainage generation from waste rock. (Licentiate dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Suitability of industrial residues for preventing acid rock drainage generation from waste rock
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Alternative title[sv]
Lämplighet av industriella restmaterial för att förhindra bildning av surt lakvatten från gråberg
Abstract [en]

One of the main and most challenging environmental problems related to mining is the generation of acid rock drainage (ARD), a leachate characterized by low pH and elevated concentrations of sulfate, metals, and metalloids formed when sulfide-bearing minerals are subjected to oxygen and water. During the operation of a mine, waste rock is often deposited in heaps and usually left under ambient conditions, enabling sulfides to oxidize. Generated ARD is commonly treated actively with alkaline material in an attempt to raise the pH and precipitate metals, with subsequent formation of sludge, which requires additional treatment. To focus on the treatment of waste rock rather than the ARD could prevent the generation of ARD; reduce the lime consumption, costs, and sludge treatment. This thesis aims to identify and evaluate the potential of different industrial residues to maintain circumneutral pH in a sulfide oxidation environment, allowing secondary minerals to form on the reactive sulfide surface to prevent sulfide oxidation and generation of ARD.

Five different industrial residues (blast furnace slag, granulated blast furnace slag, cement kiln dust, bark ash, and lime kiln dust) were selected in a feasibility study performed prior to this study. The selection was based primarily on their alkaline properties, availability, and early yield. The waste rock was selected due to its high content of sulfides (>50%) and potential to generate ARD. Initial characterization of the industrial residues included combining mineralogical and chemical composition with batch testing (L/S 10). Sulfide oxidation in the leaching of the waste rock accelerated after week 29 resulting in high concentrations of major elements such as Al, Fe and S but also extremely high concentrations of e.g. As, Cu, Mn, Pb, Sb and Zn despite their relatively low content in the waste rock. Leaching was conducted during 14-153 weeks. The initial characterization implied that all of the studied industrial residues has the potential to prevent ARD generation. However, the enrichment and leachability of Pb in the cement kiln dust, as well as Cr and Zn in the bark ash, suggested the presence of elements of potential concern that could limit the use of the materials. When the industrial residues were added to the waste rock surface in small-scale laboratory test cells, blast furnace slag, granulated blast furnace slag, and cement kiln dust self-cemented and failed to maintain circumneutral pH, whereas bark ash (1wt.%) prevented acidity, metal and metalloid leaching. However, the use of bark ash may prove problematic due to the release of Cl, K, and Na likely related to salt dissolution. Lime kiln dust (5wt.%), the most promising of the industrial residues, maintained a circumneutral pH throughout the time of leaching, with an overall decrease of metal and metalloid concentrations by more than 99.9%. Results from investigations of secondary minerals formed combined with element release during the leaching period suggest that the addition of LKD to the waste rock led to decreasing concentrations of S in the leachate due to decreased sulfide oxidation, which subsequently led to gypsum dissolution. Moreover, the addition of LKD to the waste rock generated a lower amount of secondary minerals compared to when no addition was made.

The results from these studies increase the understanding of advantages and limitations of using selected industrial residues in the treatment of mine waste. Moreover, it shows that a rather small amount of alkaline material, corresponding to 4% of the net neutralizing potential of waste rock, can prevent the acceleration of sulfide oxidation and subsequent release of sulfate, metals, and metalloids. However, the quantity and long-term stability of the formed secondary minerals need to be evaluated and understood before this method can be applied at larger scale.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-68490 (URN)978-91-7790-132-7 (ISBN)978-91-7790-133-4 (ISBN)
Presentation
2018-06-19, E632, 10:00 (English)
Opponent
Supervisors
Available from: 2018-04-25 Created: 2018-04-24 Last updated: 2018-06-12Bibliographically approved
Nyström, E., Kaasalainen, H. & Alakangas, L. (2017). Prevention of Sulfide Oxidation in Waste Rock using By-products and Industrial Remnants: a Suitability Study. In: Wolkersdorfer, C.; Sartz, L.; Sillanpää, M. & Häkkinen, A (Ed.), Mine Water & Circular Economy: A Green Congress. Paper presented at 13th International Mine Water Association Congress – “Mine Water & Circular Economy – A Green Congress”, Lappeenranta, Finland, 25-30 June 2017 (pp. 1170-1178). , 2
Open this publication in new window or tab >>Prevention of Sulfide Oxidation in Waste Rock using By-products and Industrial Remnants: a Suitability Study
2017 (English)In: Mine Water & Circular Economy: A Green Congress / [ed] Wolkersdorfer, C.; Sartz, L.; Sillanpää, M. & Häkkinen, A, 2017, Vol. 2, p. 1170-1178Conference paper, Published paper (Refereed)
Abstract [en]

Prevention and mitigation of acid rock drainage from mining are decisive for limiting environmental impact. Five by-products and industrial remnants (lime kiln dust, blast furnace slag, granulated blast furnace slag, cement kiln dust and fly ash) were investigated for their suitability to prevent acidity and metal(loid)s during leaching from highly sulfidic (50wt%, sulfide) waste rock in small scale laboratory test cells. Variations in pH and electrical conductivity in leachate allowed differentiation between the different materials. Lime kiln dust (5wt%) and fly ash (1 and 2.5wt%) were observed to be the most suitable materials to prevent acidity and metal(loid)s leaching.

National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-66362 (URN)
Conference
13th International Mine Water Association Congress – “Mine Water & Circular Economy – A Green Congress”, Lappeenranta, Finland, 25-30 June 2017
Available from: 2017-11-02 Created: 2017-11-02 Last updated: 2017-11-24Bibliographically approved
Nyström, E. (2015). Aktivitet: EGU General Assembly 2015 (ed.). Paper presented at .
Open this publication in new window or tab >>Aktivitet: EGU General Assembly 2015
2015 (English)Other (Other (popular science, discussion, etc.))
National Category
Geochemistry
Research subject
Tillämpad geokemi
Identifiers
urn:nbn:se:ltu:diva-36397 (URN)25127a53-7258-4246-9e1f-afacbb2f9b1b (Local ID)25127a53-7258-4246-9e1f-afacbb2f9b1b (Archive number)25127a53-7258-4246-9e1f-afacbb2f9b1b (OAI)
Note
Evenemang (konferens etc): EGU General Assembly 2015 : 12/04/2015 - 17/04/2015; Startdatum: 14/04/2015; Slutdatum: 14/04/2015; Roll: Deltagare; Typ: Organiserade av och deltagande i konferenser, workshops, kurser, seminarier - Deltagande i workshop, seminarium, kursAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Nyström, E. & Alakangas, L. (2015). Prevention of sulfide oxidation in sulfide-rich waste rock. In: (Ed.), : . Paper presented at EGU General Assembly 2015.
Open this publication in new window or tab >>Prevention of sulfide oxidation in sulfide-rich waste rock
2015 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-74344 (URN)
Conference
EGU General Assembly 2015
Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-06-11
Alakangas, L., Maurice, C., Macsik, J., Nyström, E., Sandström, N., Andersson-Wikström, A. & Hällström, L. (2014). Kartläggning av restprodukter för efterbehandling och inhibering av gruvavfall: funktion tillgång och logistik (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Kartläggning av restprodukter för efterbehandling och inhibering av gruvavfall: funktion tillgång och logistik
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2014 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2014. p. 86
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-24560 (URN)b78d91cf-a10d-4643-8e64-6ad24e133129 (Local ID)b78d91cf-a10d-4643-8e64-6ad24e133129 (Archive number)b78d91cf-a10d-4643-8e64-6ad24e133129 (OAI)
Projects
Användning av restprodukter för förhindrande sulfid oxidation i reaktivt gruvavfall- en förstudie
Note

Godkänd; 2014; 20140416 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-05-21Bibliographically approved
Alakangas, L., Maurice, C., Nyström, E. & Siren, S. (2014). Project: Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes. Paper presented at .
Open this publication in new window or tab >>Project: Utilization of Industrial Residuals for Prevention of Sulphide Oxidation in Mine Wastes
2014 (English)Other (Other (popular science, discussion, etc.))
Keywords
Prevention, sulfid oxidation, mine waste
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-36030 (URN)313a3b5c-2a71-4ec4-8dc3-c5474d419b91 (Local ID)313a3b5c-2a71-4ec4-8dc3-c5474d419b91 (Archive number)313a3b5c-2a71-4ec4-8dc3-c5474d419b91 (OAI)
Note

Publikationer: Evaluation of mixtures of green liquor dregs and till for application as a sealing layer on sulfidic mine wastes; Status: Pågående; Period: 01/09/2014 → 31/12/2016

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-21Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5101-9156

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