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Publications (10 of 14) Show all publications
Kaasalainen, H., Lundberg, P., Aiglsperger, T. & Alakangas, L. (2019). Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock. Environmental science and pollution research international, 26(20), 20712-20730
Open this publication in new window or tab >>Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock
2019 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 26, no 20, p. 20712-20730Article in journal (Refereed) Published
Abstract [en]

The best available technology for preventing the formation of acid drainage water from the sulfidic waste rock at mine closure aims to limit the oxygen access to the waste. There is, however, a concern that contaminants associated with secondary minerals become remobilized due to changing environmental conditions. Metal(loid) mobility from partially oxidized sulfidic waste rock under declining and limited oxygen conditions was studied in unsaturated column experiments. The concentrations of sulfate and metal(loid)s peaked coincidently with declining oxygen conditions from 100 to < 5 sat-% and to a lesser extent following a further decrease in the oxygen level during the experiment. However, the peak concentrations only lasted for a short time and were lower or in the similar concentration range as in the leachate from a reference column leached under atmospheric conditions. Despite the acid pH (~ 3), the overall quality of the leachate formed under limited oxygen conditions clearly improved compared with atmospheric conditions. In particular, the release of As was two orders of magnitude lower, while cationic metals such as Fe, Cu, Mn, and Zn also decreased, although to a lesser extent. Decreased sulfide oxidation is considered the primary reason for the improved water quality under limited oxygen conditions. Another reason may be the immobility of Fe with the incorporation of metal(loid)s in Fe(III) minerals, in contrast to the expected mobilization of Fe. The peaking metal(loid) concentrations are probably due to remobilization from solid Fe(III)-sulfate phases, while the relatively high concentrations of Al, Mn, and Zn under limited oxygen conditions were due to release from the adsorbed/exchangeable fraction. Despite the peaking metal(loid) concentrations during declining oxygen conditions, it is clear that the primary remediation goal is to prevent further sulfide oxidation.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Metal mobility, Mine closure, Mine waste, Remediation, Waste rock, Water quality
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-74538 (URN)10.1007/s11356-019-05115-z (DOI)000473172800058 ()31104229 (PubMedID)2-s2.0-85066092530 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-12 (johcin)

Available from: 2019-06-14 Created: 2019-06-14 Last updated: 2019-11-22Bibliographically approved
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 international, 26(25), 25945-25957
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 international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 26, no 25, p. 25945-25957Article in journal (Refereed) Published
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)000483698500046 ()31273653 (PubMedID)
Note

Validerad;2019;Nivå 2;2019-09-24 (johcin)

Available from: 2019-07-10 Created: 2019-07-10 Last updated: 2019-11-22Bibliographically approved
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)000477784000052 ()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: 2019-11-22Bibliographically approved
Kaasalainen, H., Stefánsson, A. & Druschel, G. K. (2017). Geochemistry and speciation of Fe(II) and Fe(III) in natural geothermal water, Iceland. Applied Geochemistry, 87, 146-157
Open this publication in new window or tab >>Geochemistry and speciation of Fe(II) and Fe(III) in natural geothermal water, Iceland
2017 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 87, p. 146-157Article in journal (Refereed) Published
Abstract [en]

The geochemistry of Fe(II) and Fe(III) was studied in natural geothermal waters in Iceland. Samples of surface and spring water and sub-boiling geothermal well water were collected and analyzed for Fe(II), Fe(III) and Fetotal concentrations. The samples had discharge temperatures in the range 27–99 °C, pH between 2.46 and 9.77 and total dissolved solids 155–1090 mg/L. The concentrations of Fe(II) and Fe(III) were determined in the <0.2 μm filtered and acidified fraction using a field-deployed ion chromatography spectrophotometry (IC-Vis) method within minutes to a few hours of sampling in order to prevent post-sampling changes. The concentrations of Fe(II) and Fe(III) were <0.1–130 μmoL/L and <0.2–42 μmoL/L, respectively. In-situ dialysis coupled with Fe(II) and Fe(III) determinations suggest that in some cases a significant fraction of Fe passing the standard <0.2 μm filtration method may be present in colloidal/particulate form. Therefore, such filter size may not truly represent the dissolved fraction of Fe but also nano-sized particles. The Fe(II) and Fe(III) speciation and Fetotal concentrations are largely influenced by the water pH, which in turn reflects the water type formed through various processes. In water having pH of ∼7–9, the total Fe concentrations were <2 μmoL/L with Fe(III) predominating. With decreasing pH, the total Fe concentrations increased with Fe(II) becoming increasingly important and predominating at pH < 3. In particular in waters having pH ∼6 and above, iron redox equilibrium may be approached with Fe(II) and Fe(III) possibly being controlled by equilibrium with respect to Fe minerals. In many acid waters, the Fe(II) and Fe(III) distribution may not have reached equilibrium and be controlled by the source(s), reaction kinetics or microbial reactions

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-66309 (URN)10.1016/j.apgeochem.2017.10.021 (DOI)000416485300013 ()2-s2.0-85034833730 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-29 (andbra)

Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2017-12-14Bibliographically 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: 2019-11-22Bibliographically approved
Kaasalainen, H., Stefansson, A. & Druschel, G. K. (2016). Determination of Fe(II), Fe(III) and Fetotal in thermal water byion chromatography spectrophotometry (IC-Vis). International Journal of Environmental Analytical Chemistry, 96(11), 1074-1090
Open this publication in new window or tab >>Determination of Fe(II), Fe(III) and Fetotal in thermal water byion chromatography spectrophotometry (IC-Vis)
2016 (English)In: International Journal of Environmental Analytical Chemistry, ISSN 0306-7319, E-ISSN 1029-0397, Vol. 96, no 11, p. 1074-1090Article in journal (Refereed) Published
Abstract [en]

Determination of iron speciation in water is one of the major challenges in environmental analytical chemistry. Here, we present and discuss a method for sampling and analysis of dissolved Fe(II), Fe(III), and Fetotal concentrations in natural thermal water covering a wide range of temperature, pH, chemical composition, and redox conditions. Various methods were tried in the collection, preservation, and storage of natural thermal water samples for the Fe(II) and Fe(III) determinations, yet the resultant Fe speciation determined was often found to be significantly affected by the methodology applied. Due to difficulties in preserving accurate Fe speciation in natural samples for later laboratory analysis, a field-deployed on-site method using ion-chromatography and spectrophotometry was developed and tested. The IC-Vis method takes advantage of ion chromatographic separation of Fe(II) and Fe(III), followed by post-column colour reaction and spectrophotometric detection, thus allowing analysis of Fe(II) and Fe(III) in a single 15-minute run. Additionally, Fetotal can be determined after sample oxidation. The analytical detection limits are ~2 µg L−1 (LOD) using 200–1000 µL injection volumes and depend on the blank and reagent quality. The power of this method relies on the capability to directly determine a wide range of absolute and relative concentrations of Fe(II) and Fe(III) in the field. The field-deployed IC-Vis method was applied for the determination of Fe(II) and Fe(III) concentrations in natural thermal water with discharge temperatures ranging from 12°C to 95°C, pH between 2.46 and 9.75, and Fetotal concentrations ranging from a few μg L−c up to 8.3 mg L−1.

National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-60082 (URN)10.1080/03067319.2016.1232717 (DOI)000384556600006 ()
Available from: 2016-11-01 Created: 2016-11-01 Last updated: 2018-07-10Bibliographically approved
Stefánsson, A., Keller, N. S., Robin, J. G., Kaasalainen, H., Björnsdóttir, S., Pétursdóttir, S., . . . Hreggvidsson, G. Ó. (2016). Quantifying mixing, boiling, degassing, oxidation and reactivity of thermal waters at Vonarskard, Iceland (ed.). Journal of Volcanology and Geothermal Research, 309, 53-62
Open this publication in new window or tab >>Quantifying mixing, boiling, degassing, oxidation and reactivity of thermal waters at Vonarskard, Iceland
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2016 (English)In: Journal of Volcanology and Geothermal Research, ISSN 0377-0273, E-ISSN 1872-6097, Vol. 309, p. 53-62Article in journal (Refereed) Published
Abstract [en]

The chemical composition of geothermal fluids may be altered upon ascent from the reservoir to surface by processes including boiling, degassing, mixing, oxidation and water-rock interaction. In an attempt to quantify these processes, a three step model was developed that includes: (1) defining the composition of the end-member fluid types present in the system, (2) quantifying mixing between the end-members using non-reactive elemental concentrations and enthalpy and (3) quantifying the changes of reactive elements including degassing, oxidation and water-rock interaction. The model was applied to geothermal water at Vonarskard, Iceland, for demonstration having temperatures of 3-98°C, pH of 2.15-9.95 and TDS of 323-2250ppm, and was thought to be produced from boiled reservoir water, condensed steam and non-thermal water. Most geothermal water represented mixture of non-thermal water and condensed steam whereas the boiled reservoir water was insignificantly mixed. CO2 and H2S degassing was found to be quantitative in steam-heated water, with oxidation of H2S to SO4 also occurred. In contrast, major rock forming elements are enriched in steam-heated water relative to their mixing ratios, suggesting water-rock interaction in the surface zone. Boiled reservoir water observed in alkaline hot springs have, however, undergone less geochemical changes upon ascent to surface and within the surface zone.

Keywords
Geochemical modeling, Geothermal fluids, Reservoir fluid, Surface water
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-10320 (URN)10.1016/j.jvolgeores.2015.10.014 (DOI)2-s2.0-84949034696 (Scopus ID)91c840c3-5cdd-48da-83a4-02470ad09a9d (Local ID)91c840c3-5cdd-48da-83a4-02470ad09a9d (Archive number)91c840c3-5cdd-48da-83a4-02470ad09a9d (OAI)
Note

Upprättat; 2016; 20160205 (hankas)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-04-30Bibliographically approved
Kaasalainen, H., Stefánsson, A., Druschel, G. K., Nuzzio, D. & Keller, N. (2016). Speciation matters – views on iron and sulfur chemistry in geothermal water, Iceland (ed.). Paper presented at Nordic Geological Winter Meeting : 13/01/2016 - 15/01/2016. Paper presented at Nordic Geological Winter Meeting : 13/01/2016 - 15/01/2016.
Open this publication in new window or tab >>Speciation matters – views on iron and sulfur chemistry in geothermal water, Iceland
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2016 (English)Conference paper, Oral presentation only (Other academic)
National Category
Geochemistry
Research subject
Tillämpad geokemi
Identifiers
urn:nbn:se:ltu:diva-35534 (URN)a189bbf6-4e85-4ee5-83f8-09aa0e5290f8 (Local ID)a189bbf6-4e85-4ee5-83f8-09aa0e5290f8 (Archive number)a189bbf6-4e85-4ee5-83f8-09aa0e5290f8 (OAI)
Conference
Nordic Geological Winter Meeting : 13/01/2016 - 15/01/2016
Note
Upprättat; 2016; 20160205 (hankas)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Stefánsson, A., Gunnarsson, I., Kaasalainen, H. & Arnórsson, S. (2015). Chromium geochemistry and speciation in natural waters, Iceland (ed.). Applied Geochemistry, 62, 200-206
Open this publication in new window or tab >>Chromium geochemistry and speciation in natural waters, Iceland
2015 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 62, p. 200-206Article in journal (Refereed) Published
Abstract [en]

Natural waters in Iceland were collected and analyzed for chromium concentration and speciation (CrIII, CrVI and CrTOT). The water sampled included non-thermal surface and spring water, surface geothermal water, and single and two-phase geothermal well discharges with sampling temperatures of 0-178°C, pH of 2.0-9.5, and total dissolved solids (TDS) of 35-4030ppm. The total Cr concentration was between 4 the measured CrIII concentration was low, generally 8 associated with decreasing importance of mineral surface complexation. Hence, CrVI becomes an increasingly dominant form of dissolved Cr at pH above 7-8. Many groundwater drinking supplies associated with mafic rocks are characterized by moderately alkaline pH resulting in CrVI concentrations of a few ppb.

National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-7279 (URN)10.1016/j.apgeochem.2014.07.007 (DOI)2-s2.0-84943633977 (Scopus ID)59ec40a2-003a-49e2-ad79-33766ef29cb0 (Local ID)59ec40a2-003a-49e2-ad79-33766ef29cb0 (Archive number)59ec40a2-003a-49e2-ad79-33766ef29cb0 (OAI)
Note

Upprättat; 2015; Bibliografisk uppgift: A Special Issue to Honor the Geochemical Contributions of D. Kirk Nordstrom; 20160205 (hankas)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-04-30Bibliographically approved
Kaasalainen, H., Stefánsson, A., Giroud, N. & Arnórsson, S. (2015). The geochemistry of trace elements in geothermal fluids, Iceland (ed.). Applied Geochemistry, 62, 207-223
Open this publication in new window or tab >>The geochemistry of trace elements in geothermal fluids, Iceland
2015 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 62, p. 207-223Article in journal (Refereed) Published
Abstract [en]

Trace element geochemistry was studied in geothermal fluids in Iceland. The major and trace element compositions of hot springs, sub-boiling, and two-phase (liquid and vapor) wells from 10 geothermal areas were used to reconstruct the fluid composition in the aquifers at depth. Aquifer fluid temperatures ranged from 4 to 300 °C, pH values between 4.5 and 9.3, and fluids typically contained total dissolved solids

National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-5000 (URN)10.1016/j.apgeochem.2015.02.003 (DOI)2-s2.0-84943661184 (Scopus ID)3034d193-a6ca-468d-ba31-f1499376c86f (Local ID)3034d193-a6ca-468d-ba31-f1499376c86f (Archive number)3034d193-a6ca-468d-ba31-f1499376c86f (OAI)
Note

Upprättat; 2015; 20160205 (hankas)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-04-30Bibliographically approved
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