| 1. |
- Bhanbhro, Riaz, 1985-, et al.
(författare)
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Effect of Particle Size On Mechanical Properties and Particle Breakage of Tailings
- 2017
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Ingår i: Canadian geotechnical journal (Print). - 0008-3674 .- 1208-6010.
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Tidskriftsartikel (refereegranskat)abstract
- Tailings material can have different material properties depending upon the type of ore and ore refining process and particle size distribution. Tailings dams are constructed as walk away solutions. Staged construction of tailings dams may lead to breakage of particles in subsequent layers resulting in change in particle sizes of material. This may lead to change in strength parameters upon change in particle sizes. This paper presents the direct shear tests performed on tailings material from a tailings dam. Remolded samples were manufactured in laboratory. The tailings material is separated in to four different particle sizes i.e.1-0.5mm, 0.5-0.25mm, 0.25-0.125mm and 0.125-0.063mm. The tests are performed on different normal stress levels as 50, 100, 150, 300 and 500kPa.The strength parameters are evaluated for each particle size and compared with said particle sizes. In order to study the effect of deposition, the tests are also performed on same material deposited in vertical and horizontal direction. This paper also describes the study of breakage of particles during direct shear tests by sieving the material at the end of each test.
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| 2. |
- Bhanbhro, Riaz, et al.
(författare)
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Evaluation Of Primary And Secondary Deformations and Particle Breakage of Tailings
- 2015
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Ingår i: From Fundamentals to Applications in Geotechnics. - : IOS Press. - 9781614996026 - 9781614996033 ; , s. 2481-2488
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Konferensbidrag (refereegranskat)abstract
- Tailings are the waste product of mining which is left over after extraction of materials of interest. Tailings material may possess different material properties depending upon type of ore and method of concentration. Sometimes the tailings material itself is used in construction of tailings dams and tailings dams are constructed to withstand for long times. A tailing dam can be exposed to settlements due to incremental load as these dams are raised in stages. Increasing load with time may also lead to particle breakage. This article presents the results from oedometer tests conducted on tailings materials. The study includes the stress-deformation behavior and particle breakage of tailings material of different gradations upon application of incremental loads in oedometer tests. The samples were collected from different sections of tailings dam from Sweden. Remolded samples were manufactured in laboratory as four batches of particle sizes i.e. 1-0.5 mm, 0.5-0.25mm, 0.25-0.125mm and 0.125-0.063mm. The results are analyzed from tested samples at different stress levels and compared with different particle sizes. The breakage of particles of each batch is analyzed by sieving the specimens after oedometer tests. The results are evaluated in terms of primary and secondary deformations. The primary and secondary deformations are also compared with different particle sized specimens.
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| 3. |
- Bhanbhro, Riaz, et al.
(författare)
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Mechanical Behavior of Uniformed Tailings Material in Triaxial Tests
- 2017
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Ingår i: Electronic Journal of Geotechnical Engineering. - : Mete Öner. - 1089-3032. ; 22:06, s. 1717-1730
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Tidskriftsartikel (refereegranskat)abstract
- Tailings dams are raised with time depending upon rate of generation of waste. A tailings dam can contain different particle sized materials within its dam body. The newly raised embankment in a tailings dam can be considered as vertical load being applied on subsequent layer. The applied loads can cause deformations and breakage of particles. The particle breakage can then lead to a skeleton with new particle size particles and hence can lead to new material properties. This paper provides the results from triaxial tests conducted on uniformed particle sizes as, 0.5mm-0.25mm, 0.25mm-0.125mm and 0.125mm-0.063mm. The tests are performed at various effective radial stresses. The results are evaluated and compared with each particle size. The results include stress-strain and volumetric behavior during shearing, the effective stress ratio and stress-dilatancy plot. The friction angles are also evaluated and compared with different particle sized specimens. It was found that effective stress ratios were slightly higher when tests were performed at lower confining stresses and vice versa. It was also observed that particle size did not show any effect of friction angles.
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| 4. |
- Dahlberg, Anders, et al.
(författare)
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786 svampar på 2015 års rödlista
- 2015
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Ingår i: Svensk Mykologisk Tidskrift. - 1653-0357. ; 36, s. 91-97-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- A new Swedish Red List was published April 28th 2015 by the Swedish Species Information Centre in which 786 species of fungi are listed. Compared to the previous Red List published in 2010, 11 species have been down-listed, 51 species have been added and 35 species have changed names or taxonomic rank, thus the list has increased by 41. The changes are mainly due to increased knowledge of taxonomy, ecology and distribution, not to changes in the sta-tus of the species. Here, the members of the Species Specialist Group for Fungi 2011 – 2015 summarize the results of the red listing.
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| 5. |
- Dahlberg, Anders, et al.
(författare)
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Svampar Fungi
- 2015
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Ingår i: Rödlistade arter i Sverige 2015. - 9789187853104 ; , s. 53-71
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Knutsson, Tommy, et al.
(författare)
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Djävulssopp, falsk djävulssopp och deras djävulskt lika dubbelgångare : röda relikter i släktena Rubroboletus och Imperator funna i Skandinavien
- 2016
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Ingår i: Svensk mykologisk tidskrift. - 0280-5057. ; 37, s. 12-25
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- By molecular methods and DNA-analyses five new genera, previously included in Boletus sect. Luridi Fr. sensu Singer, have recently been introduced, viz. Suillellus, Exsudoporus, Neoboletus, Rubroboletus and Imperator. In this paper the genera Rubroboletus and Imperator are presented in more detail. In Scandinavia three Rubroboletus species and one Imperator species have so far been reported: R. satanas, R. legaliae, R. rhodoxanthus and I. rhodopurpureus. All of them are red-listed and extremely rare in Scandinavia, which is the northern limit of their European distributions. They are considered relict species from earlier, warmer periods. All species prefer open, sun-exposed localities in broad-leaved woodlands or tree-covered pastures and meadows. Historically these species have caused much taxonomic confusion. This paper presents the current knowledge of the species characteristics, ecology and distributions in Scandinavia.
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| 7. |
- Rodriguez, Juan, et al.
(författare)
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Effect of vertical load on tailings particles
- 2016
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Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 6:2, s. 115-129
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Tidskriftsartikel (refereegranskat)abstract
- Tailing dams could store hundreds, thousands or millions of cubic meters of tailings result of the mining extractive industry. Mechanical behavior of this man-made soil should be known in order to maintain a safe storage. Dykes rise up to form the dams and they are buildup with the same tailing material especially in the upstream method using the coarse part. The study uses oedometer classical test to determine the load effect over tailing coarse particles. Tailings are site specific and so its characteristics. It is necessary to understand the tailings degradations to achieve safe impounds. The study comprises four samples of one range-size tailing particles (e.g. 1-0.5, 0.5-0.25, 0.25-0.125, 0.125-0.063mm) subject to vertical load in traditional oedometers. Vertical load effects are measured using two dimensional image analysis and sieving. Results show that 0.063mm sample is the only one that has change in shape with low breakage (<1%) while the rest of the sizes have no shape change but high breakage is present especially in fraction 0.5mm. Settlements also are more pronounced in coarse fractions 0.5 and 0.25mm.
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| 8. |
- Rodriguez, Juan, et al.
(författare)
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Mechanical weathering effect on tailing particles
- 2016
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Ingår i: Proceedings of Nordic Conference on Soil Mechanics and Geotechnical NGM.
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Konferensbidrag (refereegranskat)abstract
- Over the last century the tailing volume generation has grown dramatically due to the mineral demand. Nowadays the mining industry is producing every year millions of tons of tailings. The storage of the tailings has become a challenge due to the increased storage capacity demanded. Physical risk associated to the tailings dams is the stability itself since tailing dams are considered a walk-away solution. Physical changes as breakage and shape occur to the tailing particles affecting the stability of the fills by reduced strength properties. In order to understand the reduction and shape changes of tailing particles degradation test by milling attrition (erosion) and image analysis was conducted. Uniform fractions 1-0.5, 0.5-025, 0.25-0.125 and 0.125-0.063mm were used.Results have shown that attrition agents e.g. ball attrition can increase the physical erosion but also change the shape of the particles compared with autogenous attrition. However particles shape has become more regular (less elongated) and rounded in coarse fractions 1-0.5 and 0.5-0.25mm while smaller fractions 0.25-0.125 and 0.125-0.063mm seems to have opposite behavior. Comparison with previous milling studies show consistent differences probably due to the breakage of the particles was the objective. In perspective if tailings become more rounded the strength could be compromised. More studies are needed to verify this.
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| 9. |
- Sundberg, Sebastian, et al.
(författare)
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Nytt i nya rödlistan
- 2015
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 109, s. 188-207
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The new Swedish Red List of vascular plants, bryophytes, algae, lichens and macrofungi is briefly presented. These groups now comprise more than 1800 red-listed species, corresponding to 21% of the assessed species. A net increase of 170 red-listed species since 2010 is mainly the result of more data to base the assessments on. For the first time, four sections in the plant genus Hieracium have been assessed, resulting in an addition of 327 apomictic plant species to the Red List. Logging of old-growth forest and overgrowth of former open and semi-open habitats (mainly because of ceased management of semi-natural habitats) are the stressors that harm most species, while eutrophication, drainage, water level regulation and exploitation are also important. The dieback of the elm species Ulmus glabra, U. minor, and ash Fraxinus excelsior, because of invasive pathogens, negatively affects many species of lichens, fungi and bryophytes being dependent on these host trees. In the forest landscape, the main challenge is to allow forestry without clear-cutting large areas and to maintain mixed stands regarding tree species and age distribution. In the agricultural landscape the challenge is to maintain and improve management by grazing and mowing in semi-natural grasslands, but also wooded areas, despite a continuous decline in the number of domestic cattle. In valuable wetlands and lakes, the negative impact of old ditches and water level regulation should be reduced. Species conservation in urban areas, like cities (lawns, parks and gardens), road verges and former sandpits, poses a promising challenge where much more could be done to improve the situation for red-listed species.
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| 10. |
- Svensson, Måns, et al.
(författare)
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Taxonomic novelties and new records of Fennoscandian crustose lichens
- 2017
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Ingår i: MycoKeys. - : Pensoft Publishers. - 1314-4057 .- 1314-4049. ; :25, s. 51-86
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Tidskriftsartikel (refereegranskat)abstract
- We present taxonomic, distributional and ecological notes on Fennoscandian crustose lichens and lichenicolous fungi, based on new collections as well as revision of herbarium material. Two new combinations are proposed: Frutidella furfuracea comb. nov. for F. pullata and Puttea duplex comb. nov. for Fellhanera duplex. Lecidea byssoboliza, L. carneoglauca and Variolaria torta are all reduced to synonymy with Bacidia antricola, Bacidia invertens is synonymized with B. igniarii, B. atrolivida with Mycobilimbia tetramera, and Gyalidea fruticola with Thelenella pertusariella. A new description is provided for Micarea hylocomii. 25 species of lichens and lichenicolous fungi are reported as new to Finland, Norway and/or Sweden: Absconditella lignicola (Norway), Bacidia antricola (Norway), B. polychroa (Norway), B. pycnidata (Sweden), Bacidina adastra (Sweden), Biatora veteranorum (Norway), Briancoppinsia cytospora (Finland), Catillaria scotinodes (Norway), Cliostomum subtenerum (Norway), Dirina fallax (Sweden), Fellhaneropsis almquistiorum (Norway), Gyalidea subscutellaris (Sweden), Lecania inundata (Norway), L. suavis (Norway), Micarea capitata (Norway), M. deminuta (Norway), M. hylocomii (Sweden), M. lynceola (Sweden), M. soralifera (Sweden), M. subconfusa (Sweden), Mycoblastus sanguinarioides (Finland, Sweden), Paralecia pratorum (Sweden), Puttea duplex (Sweden), Sarcogyne algoviae (Finland) and Toninia subnitida (Norway). Lectotypes are designated for Bacidia antricola, Lecidea byssoboliza, Lecidea carneoglauca, Lecidea subconfusa and Lecidea submoestula.
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