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Liu, J.-l., Yao, J., Wang, F., Min, N., Gu, J.-h., Li, Z.-f., . . . Alakangas, L. (2019). Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation. Environmental Pollution, 274, 98-107
Open this publication in new window or tab >>Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation
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2019 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 274, p. 98-107Article in journal (Refereed) Published
Abstract [en]

Abandoned nonferrous metal(loid) tailings sites are anthropogenic, and represent unique and extreme ecological niches for microbial communities. Tailings contain elevated and toxic content of metal(loid)s that had negative effects on local human health and regional ecosystems. Microbial communities in these typical tailings undergoing natural attenuation are often very poorly examined. The diversity and inferred functions of bacterial communities were examined at seven nonferrous metal(loid) tailings sites in Guangxi (China), which were abandoned between 3 and 31 years ago. The acidity of the tailings sites rose over 31 years of site inactivity. Desulfurivibrio, which were always coupled with sulfur/sulfide oxidation to dissimilate the reduction of nitrate/nitrite, were specific in tailings with 3 years abandonment. However, genus beneficial to plant growth (Rhizobium), and iron/sulfur-oxidizing bacteria and metal(loid)-related genera (Acidiferrobacter and Acidithiobacillus) were specific within tailings abandoned for 23 years or more. The increased abundance of acid-generating iron/sulfur-oxidizing and metal(loid)-related bacteria and specific bacterial communities during the natural attenuation could provide new insights for understanding microbial ecosystem functioning in mine tailings. OTUs related to Sulfuriferula, Bacillus, Sulfurifustis, Gaiella, and Thiobacillus genera were the main contributors differentiating the bacterial communities between the different tailing sites. Multiple correlation analyses between bacterial communities and geochemical parameters indicated that pH, TOC, TN, As, Pb, and Cu were the main drivers influencing the bacterial community structures. PICRUSt functional exploration revealed that the main functions were related to DNA repair and recombination, important functions for bacterial adaptation to cope with the multi-contamination of tailings. Such information provides new insights to guide future metagenomic studies for the identification of key functions beyond metal-transformation/resistance. As well, our results offers novel outlooks for the management of bacterial communities during natural attenuation of multi-contaminated nonferrous metal(loid) tailings sites. 

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Bacterial community succession, metal(loid)s, Natural attenuation, Nonferrous metal(loid) tailings
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-72845 (URN)10.1016/j.envpol.2018.12.045 (DOI)30669085 (PubMedID)2-s2.0-85060916615 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-11 (svasva)

Available from: 2019-02-11 Created: 2019-02-11 Last updated: 2019-02-28Bibliographically approved
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: 2019-08-16Bibliographically 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
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
Liu, J.-l., Yao, J., Wang, F., Ni, W., Liu, X.-y., Sunahara, G., . . . Li, Z.-f. (2018). China's most typical nonferrous organic-metal facilities own specific microbial communities. Scientific Reports, 8(1), Article ID 12570.
Open this publication in new window or tab >>China's most typical nonferrous organic-metal facilities own specific microbial communities
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 12570Article in journal (Refereed) Published
Abstract [en]

The diversity and function of microorganisms have yet to be explored at non-ferrous metal mining facilities (NMMFs), which are the world's largest and potentially most toxic sources of co-existing metal(loid)s and flotation reagents (FRs). The diversity and inferred functions of different bacterial communities inhabiting two types of sites (active and abandoned) in Guangxi province (China) were investigated for the first time. Here we show that the structure and diversity of bacteria correlated with the types of mine sites, metal(loid)s, and FRs concentrations; and best correlated with the combination of pH, Cu, Pb, and Mn. Combined microbial coenobium may play a pivotal role in NMMFs microbial life. Arenimonas, specific in active mine sites and an acidophilic bacterium, carries functions able to cope with the extreme conditions, whereas Latescibacteria specific in abandoned sites can degrade organics. Such a bacterial consortium provides new insights to develop cost-effective remediation strategies of co-contaminated sites that currently remain intractable for bioremediation.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-70592 (URN)10.1038/s41598-018-30519-1 (DOI)000442387900034 ()30135589 (PubMedID)2-s2.0-85052145242 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-27 (andbra)

Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-09-10Bibliographically approved
Karlsson, T., Räisänen, M. L., Lehtonen, M. & Alakangas, L. (2018). Comparison of static and mineralogical ARD prediction methods in the Nordic environment. Environmental Monitoring & Assessment, 190(12), Article ID 719.
Open this publication in new window or tab >>Comparison of static and mineralogical ARD prediction methods in the Nordic environment
2018 (English)In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 190, no 12, article id 719Article in journal (Refereed) Published
Abstract [en]

Acid rock drainage (ARD) is a major problem related to the management of mining wastes, especially concerning deposits containing sulphide minerals. Commonly used tests for ARD prediction include acid–base accounting (ABA) tests and the net acid generation (NAG) test. Since drainage quality largely depends on the ratio and quality of acid-producing and neutralising minerals, mineralogical calculations could also be used for ARD prediction. In this study, several Finnish waste rock sites were investigated and the performance of different static ARD test methods was evaluated and compared. At the target mine sites, pyrrhotite was the main mineral contributing to acid production (AP). Silicate minerals were the main contributors to the neutralisation potential (NP) at 60% of the investigated mine sites. Since silicate minerals appear to have a significant role in ARD generation at Finnish mine waste sites, the behaviour of these minerals should be more thoroughly investigated, especially in relation to the acid produced by pyrrhotite oxidation. In general, the NP of silicate minerals appears to be underestimated by laboratory measurements. For example, in the NAG test, the slower-reacting NP-contributing minerals might require a longer time to react than is specified in the currently used method. The results suggest that ARD prediction based on SEM mineralogical calculations is at least as accurate as the commonly used static laboratory methods.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
ABA test, NAG test, SEM, Waste rock, Risk assessment
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-71593 (URN)10.1007/s10661-018-7096-2 (DOI)000450098200002 ()30426238 (PubMedID)2-s2.0-85056501281 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-15 (johcin)

Available from: 2018-11-15 Created: 2018-11-15 Last updated: 2018-12-04Bibliographically approved
Hällström, L., Alakangas, L. & Martinsson, O. (2018). Geochemical characterization of W, Cu and F skarn tailings at Yxsjöberg, Sweden. Journal of Geochemical Exploration, 194, 266-279
Open this publication in new window or tab >>Geochemical characterization of W, Cu and F skarn tailings at Yxsjöberg, Sweden
2018 (English)In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 194, p. 266-279Article in journal (Refereed) Published
Abstract [en]

Little attention has been paid to tailings from skarn ore deposits and their environmental impact, even though they can contain elevated concentrations of elements of potential concern together with sulfides and fluorite. Historical skarn tailings at Yxsjöberg, Sweden, containing e.g. Be, Bi, Cu, F, Sn, S, W, and Zn were geochemically characterized as a first step to evaluate the environmental impact and the potential to re-mine the tailings. The tailings were deposited between 1897 and 1963 in the Smaltjärnen Repository without dams or a complete cover, and have been in contact with the atmosphere for >30 years. Four vertical cores throughout the tailings were taken and divided into 134 subsamples, which were analyzed for total concentrations and paste pH. Selected samples from different depths were mineralogically characterized using optical microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), Raman vibrational spectroscopy, and X-ray diffraction (XRD). Minerals, hand-picked from drilled rock cores, were analyzed for the element content, and a modified Element to Mineral Conversion (EMC) that pinpoints the quantitative distribution of elements between the minerals in the tailings was carried out. The average concentrations of Be, Bi, Cu, Sn, Zn, W, F and S in the tailings were 284, 495, 946, 559, 301, and 960 ppm, and 1.9 and 1.2 wt%, respectively. The tailings has reached a late stage development due to pyrrhotite oxidation resulting in low pH (<4) in the uppermost tailings, and formations of secondary minerals such as gypsum, hydrous ferric oxides (HFO) and orthogonal calcite. Secondary pyrite and magnetite, formed from monoclinic pyrrhotite was detected, and different weathering rates of secondary pyrite, hexagonal and monoclinic pyrrhotite was indicated, with secondary pyrite as the most stable and monoclinic pyrrhotite as the least. The rare and easily-weathered mineral danalite (Fe4Be3(SiO4)3S) was found in the drilled rock cores and by XRD in the tailings. However, the mineral could not be found by optical microscopy or SEM-EDS. This suggests that the mineral has been weathered to a great extent, which poses a high risk of releasing elements of potential concern to the groundwater since danalite contains approximately 40% of the total Be and Zn concentrations in the tailings. Fluorine was mainly found in fluorite, Cu in chalcopyrite, and Bi in bismuthinite; which all showed signs of weathering in acidic condition in the uppermost part, subsequent with decreased concentrations, followed by accumulation peaks deeper down in the tailings correlated with Al. Tungsten was mainly found in scheelite; most grains were unweathered, but a few grains had altered rims or HFO on the mineral surfaces. Tin was mainly found in ferrohornblende, hedenbergite and grossular. Beryllium, Cu, F, and Zn has high potential to be released to the surrounding environment from the Smaltjärnen Repository, while W, Bi and Sn are relatively stable in the tailings. Most of the scheelite is intact and re-mining could, therefore, be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of critical raw materials in the EU.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Geology Geochemistry
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-70827 (URN)10.1016/j.gexplo.2018.09.001 (DOI)000447940000021 ()2-s2.0-85053199965 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-21 (svasva)

Available from: 2018-09-11 Created: 2018-09-11 Last updated: 2018-11-15Bibliographically approved
Hällström, L., Alakangas, L. & Martinsson, O. (2018). Metal Release from Acidic and Near-Neutral pH-Conditions in Historical W, Cu and F Skarn Tailings at Yxsjöberg, Sweden. In: Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Ed.), 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. 351-356). , 1
Open this publication in new window or tab >>Metal Release from Acidic and Near-Neutral pH-Conditions in Historical W, Cu and F Skarn Tailings at Yxsjöberg, Sweden
2018 (English)In: 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity / [ed] Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G., 2018, Vol. 1, p. 351-356Conference paper, Published paper (Refereed)
Abstract [en]

Weathering products stored in the pore water and/or as easily soluble salts in historical skarn tailings containing Be, Bi, Cu, W, and Zn, were released in water soluble fraction in the upper-most acidic tailings, at the visual oxidation front (1.5m), and/or below 2.5m (pH>7). Thus, there is a risk that these metals can pollute receiving waters by neutral mine drainage. Re-mining the tailings could be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of metals.

National Category
Geochemistry
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-71880 (URN)9780620806503 (ISBN)
Conference
11th ICARD IMWA MWD Conference “Risk to Opportunity” (ICARD 2018), September 10-14, 2018, Pretoria, South Africa.
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2019-01-15Bibliographically approved
Salifu, M., Aiglsperger, T., Hällström, L., Martinsson, O., Billström, K., Ingri, J., . . . Alakangas, L. (2018). Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes. Applied Geochemistry, 99, 42-54
Open this publication in new window or tab >>Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes
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2018 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 99, p. 42-54Article in journal (Refereed) Published
Abstract [en]

Interpretation of geochemical data based primarily on elemental concentrations often lead to ambiguous results due to multiple potential sources including mineral weathering, atmospheric input, biological cycling, mineral precipitation and exchange processes. The 87Sr/86Sr ratio is however not fractionated by these processes. In this study, Sr isotope (87Sr/86Sr) ratios have been coupled with chemical data of Sr and Rb-bearing minerals, tailings and leachates (water-soluble) to gain insight into the geochemical processes occurring within the Yxsjöberg Cu-W mine tailings, Sweden. The tailings have been exposed to oxidizing conditions resulting in three geochemical zones namely (i) oxidized, (ii) transition and (iii) unoxidized zones. Leachates from the oxidized zone are acidic (pH = 3.6–4.5) and contain elevated concentrations of metals (e.g. Fe, Cu and Zn) and SO4. The low pH has also led to subsequent weathering of most silicates, releasing Al, Ca, Mg and Na into solution. The 87Sr/86Sr ratio in the tailings ranges from 0.84787 to 1.26640 in the oxidized zone, 0.92660–1.06788 in the transition zone, whilst the unoxidized zone has values between 0.76452 and 1.05169. For the leachates, the 87Sr/86Sr ratio ranges from 2.44479 to 5.87552 in the oxidized zone, 1.37404–1.68844 in the transition zone and 1.03697–2.16340 in the unoxidized zone. Mixing (between mineral weathering and atmospheric sources) was identified as the major process regulating the Sr composition of the tailings and leachates. The highly radiogenic signatures of the leachates in the oxidized zone suggests weathering of biotite, K-feldspar and muscovite. Despite the very radiogenic signatures in the oxidized zone, increments in Ca/K ratios, Be, Ce, Tl, Al, Fe and SO4 concentrations in the water-soluble phase were recorded in its lower parts which suggests the dissolution of amphibole, pyroxene, plagioclase, fluorite, gypsum, Al and Fe –(oxy) hydroxides as well as cation exchange by clay minerals. Presence of clay minerals has led to the partial retainment of radiogenic 87Sr/86Sr resulting in increased 87Sr/86Sr in the solid tailings material at these depths. The 87Sr/86Sr ratios of the water-soluble phase in the transition zone is similar to that of helvine and could indicate its dissolution. In the upper part of the oxidized zone, the 87Sr/86Sr ratios and trends of Be, Ca, SO4, Tl and Zn in the water-soluble phase suggest the dissolution of gypsum which precipitated from a leachate with the isotopic signature of helvine. In the lower part of the unoxidized zone, elevated concentrations of W were recorded suggesting scheelite weathering. But the 87Sr/86Sr ratios are higher than that expected from dissolution of scheelite and indicates additional processes. Possible sources include biotite weathering and groundwater. This study reveals that when interpreting geochemical processes in mine waste environments, 87Sr/86Sr should be considered in addition to chemical constituents, as this isotopic tracer offers better insights into discriminating between different solute sources.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Strontium isotopes, Silicate weathering, Yxsjöberg, Skarn mine tailings, Water-soluble
National Category
Geochemistry Geology
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-71501 (URN)10.1016/j.apgeochem.2018.10.022 (DOI)000451029300005 ()2-s2.0-85055999912 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-07 (johcin)

Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2019-01-10Bibliographically approved
Hamberg, R., Maurice, C. & Alakangas, L. (2018). The formation of unsaturated zones within cemented paste backfill mixtures: Effects on the release of copper, nickel, and zinc. Environmental science and pollution research international, 25(21), 20809-20822
Open this publication in new window or tab >>The formation of unsaturated zones within cemented paste backfill mixtures: Effects on the release of copper, nickel, and zinc
2018 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 25, no 21, p. 20809-20822Article in journal (Refereed) Published
Abstract [en]

Flooding of cemented paste backfill (CPB) filled mine workings is, commonly, a slow process and could lead to the formation of unsaturated zones within the CPB-fillings. This facilitates the oxidation of sulfide minerals, and thereby increases the risk of trace-metal leaching. Pyrrhotitic tailings from a gold mine (CT), containing elevated concentrations of Ni, Cu and Zn, were mixed with cement and/or fly ash (1-3 wt. %) to form CT-CPB-mixtures. Pyrrhotite oxidation progressed more extensively during unsaturated conditions, where acidity resulted in dissolution of the Ni, Cu, and Zn associated with amorphous Fe-precipitates and/or cementitious phases. The establishment of acidic, unsaturated conditions in CT-CBP:s with low fractions (1 wt. %) of binders increased the Cu-release (to be higher than that from CT), owing to the dissolution of Cu-associated amorphous Fe-precipitates. In CT-CPB:s with relatively high proportions of binder, acidity from pyrrhotite oxidation was buffered to a greater extent. At this stage, Zn-leaching increased due the occurrence of fly ash-specific Zn-species soluble in alkaline conditions. Irrespective of binder proportion and water saturation level, the Ni- and Zn-release were lower, compared to that in CT. Fractions of Ni, Zn, and Cu associated with acid-soluble phases or amorphous Fe-precipitates, susceptible to remobilization under acidic conditions, increased in tandem with binder fractions. Pyrrhotite oxidation occurred irrespective of the water saturation level in the CPB-mixtures. That in turn, poses an environmental risk, whereas a substantial proportion of Ni, Cu and Zn were associated with acid-soluble phases.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Tailings management, cement, trace metal leaching
National Category
Earth and Related Environmental Sciences Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-68435 (URN)10.1007/s11356-018-2222-9 (DOI)000438830900052 ()29756187 (PubMedID)
Note

Validerad;2018;Nivå 2;2018-08-07 (andbra)

Available from: 2018-04-20 Created: 2018-04-20 Last updated: 2019-01-18Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7291-8585

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