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Qureshi, A., Maurice, C. & Öhlander, B. (2019). Effects of the co-disposal of lignite fly ash and coal mine waste rocks on AMD and leachate quality. Environmental science and pollution research international, 26(4), 4104-4115
Open this publication in new window or tab >>Effects of the co-disposal of lignite fly ash and coal mine waste rocks on AMD and leachate quality
2019 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 26, no 4, p. 4104-4115Article in journal (Refereed) Published
Abstract [en]

Lignite fly ash (FA) and waste rocks (WRs) were mixed in three different ratios (1:1, 1:3 and 1:5) and studied to compare the effects of adding FA on acid mine drainage generation from coal mining WRs, leachability of elements and the potential occurrence of the secondary minerals. FA mixed with WRs showed significant differences in pH levels compared to previous research. The 1:1 mixture performed best of all the three mixtures in terms of pH and leachability of elements, mainly due to the higher proportion of FA in the mixture. The pH in the 1:1 mixtures varied between 3.3 and 5.1 compared to other mixtures (2.3–3.5). Iron and SO42− leached considerably less from the 1:1 mixture compared to the others, indicating that the oxidation of sulphides was weaker in this mixture. Aluminium leached to a high degree from all mixtures, with concentrations varying from mg L−1 to g L−1. The reason behind this increase is probably the addition of FA which, due to acidic conditions and the composition of the FA, increases the availability of Al. For the same reason, high concentrations of Mn and Zn were also measured. Geochemical modelling indicates that the 1:1 mixture performs better in terms of precipitation of Al3+ minerals, whereas Fe3+ minerals precipitated more in mixtures containing less FA. These results suggest that, with time, the pores could possibly be filled with these secondary minerals and sulphate salts (followed by a decrease in sulphide oxidation), improving the pore water pH and decreasing the leachability of elements. Since grain size plays a crucial role in the reactivity of sulphides, there is a risk that the results from the leaching tests may have been influenced by crushing and milling of the WR samples.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Coal mine waste rock, acid mine drainage (AMD), fly ash mixing, weathering cells, PHREEQC, element leaching
National Category
Geochemistry Environmental Sciences Environmental Management Mineral and Mine Engineering
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-72667 (URN)10.1007/s11356-018-3896-8 (DOI)30560529 (PubMedID)2-s2.0-85058775217 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-12 (svasva)

Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-02-12Bibliographically approved
Jia, Y., Stahre, N., Maurice, C. & Öhlander, B. (2019). Geotechnical and chemical characterization of field-applied fly ash as sealing material over mine tailings. International Journal of Environmental Science and Technology, 16(3), 1701-1710
Open this publication in new window or tab >>Geotechnical and chemical characterization of field-applied fly ash as sealing material over mine tailings
2019 (English)In: International Journal of Environmental Science and Technology, ISSN 1735-1472, E-ISSN 1735-2630, Vol. 16, no 3, p. 1701-1710Article in journal (Refereed) Published
Abstract [en]

The present study addresses the geotechnical and chemical properties of sealing materials using a paper mill by-product, fly ash, on top of sulfide-bearing mine waste tailings after 5 years of field application. From a geotechnical perspective, the low in situ bulk density (≤ 1500 kg/m3) ensured a high degree of water saturation (90.2%) for the field-applied ash. The chemical characteristics and behaviors of the fly ash samples reflected a high long-term leaching capacity (liquid-to-solid ratio of 10 cm3/g) and high alkalinity (liquid-to-solid ratio of up to 500 cm3/g). The laboratory leaching results suggested that none of the elements released from the field-applied ash exceeded the EU limits for inert materials, and the concentrations of elements were far below the limits for hazardous materials at landfill sites. Based on the in situ and laboratory characterizations of the field-applied ash, the fly ash sealing material was considered geotechnically stable. However, a number of geotechnical parameters could not be measured due to the cementation of the ash. Moreover, the chemical composition of the field-applied ash exhibited considerable variations when compared with that of the raw ash generated from the same paper mill. Overall, the field-applied ash displayed high alkalinity and effectively buffered the acid generated from sulfidic tailings for long-term sealing purposes.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Alkalinity, Dry cover, Leaching capacity, Paper mill by-products
National Category
Geochemistry Geotechnical Engineering
Research subject
Applied Geochemistry; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-68841 (URN)10.1007/s13762-018-1738-3 (DOI)000460696700041 ()
Note

Validerad;2019;Nivå 2;2019-08-19 (johcin)

Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2019-08-19Bibliographically approved
Alakangas, L., Hanna, K., 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: 2019-11-22Bibliographically approved
Jia, Y., Hamberg, R., Qureshi, A., Mäkitalo, M. & Maurice, C. (2019). Variation of green liquor dregs from different pulp and paper mills for use in mine waste remediation. Environmental science and pollution research international, 26(30), 31284-31300
Open this publication in new window or tab >>Variation of green liquor dregs from different pulp and paper mills for use in mine waste remediation
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2019 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 26, no 30, p. 31284-31300Article in journal (Refereed) Published
Abstract [en]

The geotechnical, chemical, and mineralogical properties of green liquor dregs (GLDs) generated as byproducts from five paper mills were investigated to assess their buffering and heavy metal immobilization capacities and their roles as water and oxygen barriers. One type of GLD was further studied to test the effects of the retrieval process and the storage, drying, and hydration of GLD. The high water retention capacity of the GLDs is valuable for limiting O2diffusion. Laboratory results showed that the GLDs had hydraulic conductivities of 3.7 × 10−9–4.6 × 10−8 m/s and varied regularly in plasticity. The chemical and mineralogical compositions of the GLDs varied greatly, reflecting the raw material used to produce paper and the process used to retrieve GLDs. Although they had high total heavy metal contents, none of the leached elements from the GLDs (L/S 10 cm3/kg) exceeded the European Union’s limits for landfills of non-hazardous waste. The GLDs exhibited high buffering capacities. In a supplementary test, the buffering capacities varied (0.0041–0.0114 M H+/g GLD) over 72 d after acid was added to the GLD. Changing the filtration process did not greatly affect the GLDs’ properties but mainly affected the hydraulic conductivity, total heavy metal contents and sulfur content. Analyzing the storage of GLDs is necessary in the mining industry because remediation measures require large amounts of material over short periods. The buffering capacity of the dried GLD decreased slightly. The effect of dewatering caused by the mixing of 2% Na-lignosulfate with GLD (w/w) was low.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Acid neutralization, Buffering capacity, Heavy metals, Water retention, Plasticity, Beneficiation
National Category
Geotechnical Engineering Geochemistry
Research subject
Applied Geochemistry; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-75826 (URN)10.1007/s11356-019-06180-0 (DOI)000494047900065 ()31471848 (PubMedID)
Note

Validerad;2019;Nivå 2;2019-11-22 (johcin)

Available from: 2019-09-03 Created: 2019-09-03 Last updated: 2019-11-22Bibliographically 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
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: 2019-11-22Bibliographically approved
Jia, Y., Stahre, N., Mäkitalo, M., Maurice, C. & Öhlander, B. (2017). Elemental mobility in sulfidic mine tailings reclaimed with paper mill by-products as sealing materials (ed.). Environmental science and pollution research international, 24(25), 20389-20389
Open this publication in new window or tab >>Elemental mobility in sulfidic mine tailings reclaimed with paper mill by-products as sealing materials
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2017 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 24, no 25, p. 20389-20389Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
Springer, 2017
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-65046 (URN)10.1007/s11356-017-9650-9 (DOI)000408698700021 ()28707240 (PubMedID)2-s2.0-85023754240 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-30 (andbra)

Available from: 2017-08-14 Created: 2017-08-14 Last updated: 2018-07-10Bibliographically approved
Hamberg, R., Maurice, C. & Alakangas, L. (2017). Lowering the water saturation level in cemented paste backfill mixtures: Effect on the release of arsenic. Minerals Engineering, 112, 84-91
Open this publication in new window or tab >>Lowering the water saturation level in cemented paste backfill mixtures: Effect on the release of arsenic
2017 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 112, p. 84-91Article in journal (Refereed) Published
Abstract [en]

The Cemented Paste Backfill (CPB) method allows the mixing of dewatered tailings slurries with cementitious binders to backfill excavated underground workings. After mine closure, CPB workings are permanently flooded by rising groundwater. This flooding is considered beneficial for reducing the risk of acid generation associated with CPB containing sulphide minerals. In general, CPB workings are slowly flooded and the process may lead to regions with a low degree of water saturation to form within the CPB. This in turn, may increase oxygen ingress in the CPB, thereby prolonging oxidation of the minerals. To investigate the environmental impact of this oxidation, tailings containing elevated concentrations of arsenic (As) and pyrrhotite were handled via CPB. In this study, CPB mixtures containing 1–3 wt.% of cementitious binders and tailings was studied. The water saturation level in the CPB-mixtures was lowered as curing time extended. In mimicked flooded conditions, the mobility of As in the CPB mixtures was correlated with As-bearing cementitious phases that are sensitive to a reduction in the pH. In CPB-mixtures with lower proportions of binders, cementitious As-phases dissolved while the water saturation level decreased to form more stable As-phases. Increasing binder fractions, most of the cementitious As-phases persisted in the CPB while water saturation levels were lowered and release of As increased. Regardless of curing conditions, managing these tailings via the CPB method yielded increased mobility of As compared with that in the unmodified tailings; this resulted possibly from the formation of less acid-tolerant As species.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Geochemistry
Research subject
Applied Geochemistry
Identifiers
urn:nbn:se:ltu:diva-65077 (URN)10.1016/j.mineng.2017.05.005 (DOI)000410868200011 ()2-s2.0-85026233469 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-15 (andbra)

Available from: 2017-08-15 Created: 2017-08-15 Last updated: 2019-11-22Bibliographically approved
Mäkitalo, M., Stenman, D., Ikumapayi, F., Maurice, C. & Öhlander, B. (2016). An Evaluation of Using Various Admixtures of Green Liquor Dregs, a Residual Product, as a Sealing Layer on Reactive Mine Tailings (ed.). Mine Water and the Environment, 35(3), 283-293
Open this publication in new window or tab >>An Evaluation of Using Various Admixtures of Green Liquor Dregs, a Residual Product, as a Sealing Layer on Reactive Mine Tailings
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2016 (English)In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 3, p. 283-293Article in journal (Refereed) Published
Abstract [en]

Green liquor dregs (GLD), a residual product from sulfate paper mills, was blended with tailings, fly ash, and bark sludge with the aim of improving the material’s physical properties so that it could function as a sealing layer in dry covers on sulfidic mine waste. Geotechnical and geochemical investigations, including weathering cell tests, were carried out on GLD with admixtures to assess their effectiveness. Due to its alkaline character, GLD was shown to have the potential to improve leachate quality by decreasing metal mobility when blended with tailings. The admixtures showed favorable sealing layer properties such as high water retention capacity and low hydraulic conductivity. However, caution must be exercised when the dregs are blended with tailings containing large amounts of As and Mo, since increased leaching of these elements may be expected.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-14077 (URN)10.1007/s10230-015-0340-x (DOI)000382193900003 ()2-s2.0-84929104639 (Scopus ID)d642af46-b311-4e7d-bb0c-ba3d315001f4 (Local ID)d642af46-b311-4e7d-bb0c-ba3d315001f4 (Archive number)d642af46-b311-4e7d-bb0c-ba3d315001f4 (OAI)
Note

Validerad; 2016; Nivå 2; 2016-10-18 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Nason, P., Jia, Y., Maurice, C., Alakangas, L. & Öhlander, B. (2016). Biodegradation of Biosolids Under Aerobic Conditions: Implications for Cover Materials for Sulfide Mine Tailings Remediation (ed.). Mine Water and the Environment, 35(3), 273-282
Open this publication in new window or tab >>Biodegradation of Biosolids Under Aerobic Conditions: Implications for Cover Materials for Sulfide Mine Tailings Remediation
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2016 (English)In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 35, no 3, p. 273-282Article in journal (Refereed) Published
Abstract [en]

Sewage sludge residue (biosolids) was investigated for its potential as a long-term tailings cover. Biosolids may prevent oxygen diffusion into underlying sulfide tailings through microbial aerobic biodegradation of organic matter. Biosolids were investigated at laboratory-, pilot-, and field-scale using analysis of total organic matter (TOM) mass reduction and O2, CO2, CH4 concentrations to quantify the biodegradation rate. A 156-day, open microcosm experiment, in which the loss of biosolids mass over time at differing temperatures, mimicking ambient (20–22 °C), mesophilic (34 °C), and thermophilic (50 °C) conditions, indicated that TOM biodegradation was best in the mesophilic temperature range, with 14.8, 27.2, and 26.7 % mass depletion at ambient, mesophilic, and thermophilic conditions, respectively. The data was correlated to field-scale data that evaluated biodegradation rates via decreasing O2 and increasing CO2 concentrations. Field biodegradation rates were less than laboratory rates because lower mean annual temperatures (0.6–0.7 °C) diminished microbial activity. A calibrated model indicates that 20 % of a field application of biosolids will degrade within 2 years. However, the rate declines with time due to exhaustion of the most readily degradable organic fraction. If biodegradation cannot be maintained, the long-term effectiveness of biosolids as a covering material for mine tailings remains a concern.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-15882 (URN)10.1007/s10230-015-0339-3 (DOI)000382193900002 ()2-s2.0-84928624256 (Scopus ID)f734105d-fe2c-485f-8869-7e75ca81458c (Local ID)f734105d-fe2c-485f-8869-7e75ca81458c (Archive number)f734105d-fe2c-485f-8869-7e75ca81458c (OAI)
Note

Validerad; 2016; Nivå 2; 2016-10-18 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-11-22Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7585-4017

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