| 1. |
- Fredriksson, Karolina, et al.
(författare)
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Klassrumsdialog i matematikundervisningen : matematiska samtal i helklass i grundskolan
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna systematiska översikt ger en bild av vad forskningen sammantaget säger om hur lärare kan leda samtal i helklass för att få elever att delta i gemensamma matematiska resonemang. Det handlar om diskussioner i vilka eleverna använder och analyserar matematiska begrepp och argumenterar matematiskt. Detta är förmågor som kursplanen i matematik anger att undervisningen ska ge eleverna förutsättningar att utveckla, och som forskning lyfter fram att elever i svensk skola behöver förstärka. Översikten rör också frågor om hur lärare kan möta och ta tillvara elevers olikheter i undervisningen, närmare bestämt hur lärare kan få med elever som inte är så benägna att delta i gemensamma resonemang, och hur elevers olika idéer kan bli en del av de matematiska samtalen och berika dem. Översikten utgår från följande frågeställning:Vad kännetecknar klassrumsdialoger som engagerar elever i matematiskaresonemang och som möter och tar tillvara elevers olikheter, och vad kännetecknarlärarens ledning av sådana dialoger?Översikten är en sammanställning av arton forskningsstudier som systematiskt har valts ut av forskare efter omfattande litteratursökningar i internationella forskningsdatabaser. Sökningarna resulterade i 10 528 studier.Studierna bygger på ingående observationer och analyser av dialoger i helklass mellan lärare och elever. Det är klassrumssituationer som lärare skulle kunna känna igen sig i. Analyserna sätter ord på det som sker och ger förståelse i form av olika begrepp och strukturer. Denna vetenskapligt grundade kunskap kan utgöra stöd för lärare när de planerar och leder klassrumsdialoger i matematikundervisningen.
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| 2. |
- Hallberg, Håkan, et al.
(författare)
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Benefits and risks with acellular dermal matrix (ADM) and mesh support in immediate breast reconstruction: a systematic review and meta-analysis
- 2018
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Ingår i: Journal of Plastic Surgery and Hand Surgery. - 2000-656X .- 2000-6764. ; 52:3, s. 130-147
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Tidskriftsartikel (refereegranskat)abstract
- In modern implant-based immediate breast reconstruction, it has become common to use biological acellular dermal and synthetic matrices in combination with a tissue expander or an implant. The aim of this systematic review was to examine differences in recurrence of cancer, impact on oncological treatment, health related quality of life, complications and aesthetic outcome between matrix and no matrix in immediate breast reconstruction. Systematic searches, data extraction and assessment of methodological quality were performed according to predetermined criteria. Fifty-one studies were eligible and included in the review. The certainty of evidence for overall complication rate and implant loss is low (GRADE ⊕⊕□ □). The certainty of evidence for delay of adjuvant treatment, implant loss, infection, capsular contraction and aesthetic outcome is very low (GRADE ⊕□ □ □). No study reported data on recurrence of cancer or health related quality of life. In conclusion, there is a lack of high quality studies that compare the use of matrix with no matrix in immediate breast reconstruction. Specifically, there are no data on risk of recurrence of cancer, delay of adjuvant treatment and Health related quality of life (HRQoL). In addition, there is a risk of bias in many studies. It is often unclear what complications have been included and how they have been diagnosed, and how and when capsular contracture and aesthetic outcome have been evaluated. Controlled trials that further analyse the impact of radiotherapy, type of matrix and type of procedure (one or two stages) are necessary.
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| 3. |
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| 4. |
- Hellgren, Lovisa, et al.
(författare)
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Brain MRI and neuropsychological findings at long-term follow-up after COVID-19 hospitalisation : an observational cohort study
- 2021
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Ingår i: BMJ Open. - : BMJ Publishing Group Ltd. - 2044-6055. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To report findings on brain MRI and neurocognitive function, as well as persisting fatigue at long-term follow-up after COVID-19 hospitalisation in patients identified as high risk for affection of the central nervous system. Design Ambidirectional observational cohort study. Setting All 734 patients from a regional population in Sweden with a laboratory-confirmed COVID-19 diagnosis admitted to hospital during the period 1 March to 31 May 2020. Participants A subgroup (n=185) with persisting symptoms still interfering with daily life at a telephone follow-up 4 months after discharge were invited for a medical and neuropsychological evaluation. Thirty-five of those who were assessed with a neurocognitive test battery at the clinical visit, and presented a clinical picture concerning for COVID-19-related brain pathology, were further investigated by brain MRI. Main outcome measures Findings on brain MRI, neurocognitive test results and reported fatigue. Results Twenty-five patients (71%) had abnormalities on MRI; multiple white matter lesions were the most common finding. Sixteen patients (46%) demonstrated impaired neurocognitive function, of which 10 (29%) had severe impairment. Twenty-six patients (74%) reported clinically significant fatigue. Patients with abnormalities on MRI had a lower Visuospatial Index (p=0.031) compared with the group with normal MRI findings. Conclusions In this group of patients selected to undergo MRI after a clinical evaluation, a majority of patients had abnormal MRI and/or neurocognitive test results. Abnormal findings were not restricted to patients with severe disease.
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| 5. |
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| 6. |
- Josefsson, Sarah, 1976-, et al.
(författare)
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Capping efficiency of various carbonaceous and mineral materials for in situ remediation of marine sediments contaminated with PCDD/Fs, OCS and HCB
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The efficiency of various thin-layer capping materials in reducing the sediment-to-water flux and benthic organism bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), hexachlorobenzene (HCB) and octachlorostyrene (OCS) was investigated in a boxcosm experiment. The influence of cap layer thickness (0.5-5 cm) and different cap materials were tested using a three-factor experimental design. The capping materials consisted of a passive carrier (coarse or fine limestone material, or a marine clay sediment), and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants and decrease their bioavailability. Macrofauna was added to the boxes to get a semi-natural bioturbation. The sediment-to-water flux was measured using passive (SPMD) samplers, and the bioaccumulation by the surface-dwelling gastropod Hinia reticulata and the deep-burrowing polychaetes Nereis spp. was determined. Results showed substantial decreases in both flux and bioaccumulation as a result of thin-layer capping. The thickness of the capping layer and the choice of active material were important factors, while the use of different types of passive materials was not statistically significant for any of the observed endpoints. Flux and bioaccumulation decreased with increased cap thickness, and could be further decreased with addition of active material. Activated carbon was more efficient than lignin, and a ~90% reduction of the flux and bioaccumulation, compared to uncapped control sediment, could be achieved with 3 cm caps with 3.3% AC (g C/g ww clay). The reduction was generally larger in the surface-dwelling H. reticulata than in Nereis spp., and the magnitude of the reduction was frequently similar between Nereis spp. and sediment-to-water fluxes. The latter was interpreted to indicate a link between Nereis spp. bioirrigation and sediment-to-water fluxes. Furthermore, the reduction in sediment-to-water flux was dependent on the hydrophobicity of the congeners, with less hydrophobic congeners achieving a larger reduction than more hydrophobic congeners.
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| 7. |
- Josefsson, Sarah, et al.
(författare)
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Capping Efficiency of Various Carbonaceous and Mineral Materials for In Situ Remediation of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Contaminated Marine Sediments : Sediment-to-Water Fluxes and Bioaccumulation in Boxcosm Tests
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:6, s. 3343-3351
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of thin-layer capping in reducing sediment-to-water fluxes and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene, and octachlorostyrene was investigated in a boxcosm experiment. The influence of cap thickness (0.5-5 cm) and different cap materials was tested using a three-factor experimental design. The cap materials consisted of a passive material (coarse or fine limestone or a marine clay) and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants. The cap thickness and the type of active material were significant factors, whereas no statistically significant effects of the type of passive material were observed. Sediment-to-water fluxes and bioaccumulation by the two test species, the surface-dwelling Nassarius nitidus and the deep-burrowing Nereis spp., decreased with increased cap thickness and with addition of active material. Activated carbon was more efficient than lignin, and a ∼90% reduction of fluxes and bioaccumulation was achieved with 3 cm caps with 3.3% AC. Small increases in fluxes with increased survival of Nereis spp. indicated that bioturbation by Nereis spp. affected the fluxes.
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| 8. |
- Kristoffersson, Ida, 1980-, et al.
(författare)
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Sampers4 : Skattning av regionala efterfrågemodeller
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport har tagits fram som slutrapportering av projektet ”Sampers4 -fortsättning” finansierat av Trafikverket, som genomförts under hösten 2017 och våren 2018. Detta projekt har tagit vid där tidigare omskattningsprojekt för Sampers regionala efterfrågemodeller slutat. De största förändringarna och förbättringarna i denna senaste omskattning är:att även de som inte angivit någon inkomst i RVU har fått en inkomst påkodad,att hushållsvariabler kunnat inkluderas i skattningen på grund av framsteg inom framtagning av syntetisk befolkning med hushållsdata som kan användas vid implementering,att konsistensen mellan utbud och efterfrågan förbättrats genom att impedansen från kollektivtrafikutläggningen använts i skattning av efterfrågemodeller för färdmedelsval.Projektet ”Sampers4 –fortsättning” har avgränsats till att gälla skattning av regionala efterfrågemodeller. Implementering av modellerna har påbörjats i tidigare omskattningsprojekt, men har inte ingått i detta projekt. Vi inser att mycket av vårt arbete i detta projekt inte kunnat göras utan det arbete som gjorts i tidigare omskattningsprojekt.
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| 9. |
- Lindgren, Karin, et al.
(författare)
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Full mill model for dissolving pulp based biorefinery
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Material and energy balances of a modern theoretical dissolving softwood kraft pulp mill, using pre-hydrolysis in water, have been established. The mill produces 1000 ADt/day and there is an energy excess in the mill that could be used to produce power. If lignin is removed with the LignoBoost process the recovery boiler is unloaded enabling an increased pulp production. With a lignin removal of 0.2 ton/ADt the pulp production could increase 8.5%. According to a sensitivity analysis the lignin price has the largest impact on the economic performance.
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| 10. |
- Lindgren, Karin, et al.
(författare)
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Techno economic evaluation of lignin extraction in a dissolving pulp biorefinery
- 2017
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Ingår i: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017. - Stockholm : RISE Bioekonomi. - 9789186018207 ; , s. 118-123
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Konferensbidrag (refereegranskat)abstract
- A simulation model for dissolving pulp production using prehydrolysis kraft process has been developed at Innventia, which reflects a greenfield dissolving softwood kraft pulp mill producing 1,000tpd. The fibrelines comprised a separate prehydrolysis stage before the impregnation stage, with condensate from black liquor evaporation and steam being added to the prehydrolysis stage. The liquor was then removed from the chips and fed to the evaporation plant. The prehydrolysed chips were subjected to impregnation, cooking and oxygen delignification in double stages, with the oxygen delignified pulp being bleached in a four stage sequence D1(EOP)D2P. The simulation program WinGEMS 5.0 was used to establish material and energy balances. A lignin production of 0.2t/t increased pulp production by 8.5%. The heat value of the black liquor decreased but would still be high enough for stable and favourable combustion properties in the recovery boiler. It was found that the lignin price had the largest impact on the economic performance. Lignin removal increased the pulp production and was economically viable, especially if the possibility to produce electricity was low.
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| 11. |
- Lindman, Ida, et al.
(författare)
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Five-Year Outcomes After Arthroscopic Surgery for Femoroacetabular Impingement Syndrome in Elite Athletes
- 2020
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Ingår i: American Journal of Sports Medicine. - : SAGE Publications. - 0363-5465 .- 1552-3365. ; 48:6, s. 1416-1422
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Author(s). Background: Femoroacetabular impingement syndrome (FAIS) is a common cause of hip pain and disability in athletes. Arthroscopic treatment for FAIS is well-established; however, the long-term results in elite athletes are limited. Purpose: To evaluate outcomes 5 years after arthroscopic treatment for FAIS in elite athletes. Study Design: Case series; Level of evidence, 4. Methods: Elite athletes undergoing arthroscopic treatment for FAIS with a minimum 5-year follow-up were included. They were prospectively followed up with patient-reported outcome measures. An elite athlete was defined as having a Hip Sports Activity Scale (HSAS) level of 7 or 8 before the onset of symptoms. Preoperatively and 5 years after surgery, all athletes completed a web-based questionnaire, including the Copenhagen Hip and Groin Outcome Score (comprising 6 subscales), the EQ-5D and EQ-VAS (European Quality of Life–5 Dimensions Questionnaire and European Quality of Life–Visual Analog Scale), iHOT-12 (International Hip Outcome Tool), a visual analog scale for hip function, and the HSAS. Moreover, patients reported their overall satisfaction with their hip function. Preoperative measurements were compared with the 5-year follow-up. Results: A total of 64 elite athletes (52 men, 12 women) with a mean ± SD age of 24 ± 6 years were included. On average, patients reported a statistically significant and clinically relevant improvement from preoperative patient-reported outcome measures to the 5-year follow-up (P <.0003), Copenhagen Hip and Groin Outcome Score subscales (symptoms, 51.7 vs 71.9; pain, 61.0 vs 81.1; function of daily living, 67.1 vs 83.6; function in sports and recreation, 40.0 vs 71.5; participation in physical activity, 25.0 vs 67.4; hip and groin–related quality of life, 34.4 vs 68.0), EQ-5D (0.60 vs 0.83), EQ-VAS (66.1 vs 76.7), and iHOT-12 (40.0 vs 68.8). At the 5-year follow-up, 90.5% reported satisfaction with their overall hip function. In total, 54% still participated in competitive sports (HSAS, 5-8) at follow-up, while 77% had decreased their level. Older patients and patients with longer duration of symptoms reported a significantly lower level of sports activity (HSAS, 0-4; P <.009). Conclusion: Arthroscopic treatment for FAIS in elite athletes results in a statistically significant and clinically relevant improvement regarding symptoms, hip function, quality of life, and pain 5 years after surgery. Approximately half of the cohort was still in competitive sports at follow-up, yet 77% had decreased their level of sports. Nine of 10 patients were satisfied with their surgery.
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| 12. |
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| 13. |
- Näzelius, Ida-Linn, et al.
(författare)
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Influence of peat addition to woody biomass pellets on slagging characteristics during combustion
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:7, s. 3997-4006
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Tidskriftsartikel (refereegranskat)abstract
- Upgraded biofuels such as pellets, briquettes, and powder are today commonly used in small as well as large scale appliances. In order to cover an increasing fuel demand new materials such as bark, whole tree assortments, and peat are introduced. These materials have higher ash content which is why they are potentially more problematic compared with stem wood. In general, few studies can be found regarding cocombustion of peat and biomass and in particular where the slagging tendencies are discussed. The overall objective of this study was therefore to determine the influence of peat addition to woody biomass pellets on slagging characteristics. Two different peat assortments (peat A and B) were copelletized separately in four different dry matter levels (0-5-15-30 wt %) into stem wood and energy wood, respectively. Peat A was a traditional Scandinavian fuel peat, with a high ash and Si content (carex), and peat B had a low ash content and relatively high Ca/Si ratio (sphagnum) chosen for its special characteristics. The produced pellets were combusted in a commercial underfed pellet burner (15 kW) installed in a reference boiler. The collected deposits (bottom ash and slag) from the combustion experiments were chemically characterized by scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) and X-ray diffraction (XRD) regarding the elemental distribution and morphology and phase composition, respectively. In addition, the bottom ashes were characterized according to inductively coupled plasma atomic emission spectroscopy (ICP-AES). To interpret the experimental findings chemical equilibrium model calculations were performed. The slagging tendency increased when adding peat into the woody biomasses. Especially sawdust with its relatively low ash and Ca content was generally more sensitive for the different peat assortments. Cofiring with the relatively Si and ash rich peat A resulted in the most severe slagging tendency. A significant increment of the Si, Al, and Fe content and a significant decrement of the Ca content in the slag could be seen when increasing the content of peat A in both woody biomasses. The slagging tendency increased when adding peat A because high temperature melting Ca-Mg oxides react to form more low temperature melting Ca/Mg-Al-K silicates. The slagging tendency was significantly lower when adding the more ash poor peat B, with relatively high Ca/Si ratio, into the woody biomass fuels compared with the peat A mixtures. The slag from the peat B mixings had a slightly higher Ca content compared with the Si content and a clearly higher content of Ca compared with the peat A mixtures. There were still Ca-Mg oxides left in the bottom ash i.e. a less amount of sticky low temperature melting K-silicate rich melt was formed when peat B was added to the woody biomasses.
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| 14. |
- Samuelsson, Ida, et al.
(författare)
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Assessment of climate impact and costs comparing two railway embankment fill methods
- 2023
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Ingår i: Proceedings The Fifth International Conference on New Developments in Soil Mechanics and Geotechnical Engineering. - Cham : Springer Nature. ; , s. 181-189
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Konferensbidrag (refereegranskat)abstract
- Emissions from infrastructure projects and construction projects have a large impact on the environment. Construction activities and materials, including geotechnical engineering works, account for a great share of that impact and the monetary costs of the projects. In railway projects, crushed bedrock is often used as fill material in the embankments, and less suitable soil is excavated and transported to a landfill causing emissions. Despite that, sustainability assessments are rarely made when comparing the crushed bedrock fill method with other alternative methods, when the geotechnical engineer is designing an embankment. This paper, therefore, shows how climate impact and monetary costs can be compared for two fill methods in a railway embankment in Sweden, namely crushed rock fill and fill made of cement-stabilized sandy till. A comparing life cycle assessment (LCA) of climate impact and a life cycle cost analysis (LCCA) of monetary costs were made for the two methods. Activities and materials used in the production and construction stages were assessed. The results show that the stabilized sandy till method had both a smaller climate impact and lower life cycle cost (LCC) than the crushed bedrock fill method.
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| 15. |
- Samuelsson, Ida, et al.
(författare)
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Geoteknik ur ett livscykelperspektiv
- 2023
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Ingår i: Husbyggaren. - Stockholm. - 0018-7968. ; :1, s. 17-20
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Genom att tillämpa livscykelberäkningar där man utvärderar hela konstruktionens livscykel, från råmaterialutvinning till slutskedet, kan ett mer hållbart val av en konstruktions utformning göras. I syfte att skapa förutsättningar för att minska både konstruktionens miljöpåverkan och kostnader utvecklar man nu på avdelningen för Jord- och bergmekanik på KTH just sådana beräkningsmetoder. Här skriver forskarna på KTH om det pågående projektet som sker med finansiering från Sven Tyréns Stiftelse och Trafikverket.
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| 16. |
- Samuelsson, Ida, et al.
(författare)
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Integrating LCA and LCCA in the geotechnical design process
- 2024
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Ingår i: Proceedings of the Institution of Civil Engineers. - : Emerald. - 1478-4637 .- 1751-7664. ; 177, s. 19-30
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Tidskriftsartikel (refereegranskat)abstract
- Construction and infrastructure projects account for a large share of global emissions. Included in these projects are geotechnical engineering works, which cause environmental impact and costs throughout their lifecycle. In the geotechnical design process, the geotechnical engineer often has design choices where different methods and materials can be used. If assessments of environmental impact and costs were to be integrated into the geotechnical design process, the geotechnical work could be made more sustainable. As a result of this, there is a need for research on integrating the assessments of environmental impact and costs in the geotechnical design process. This paper, therefore, presents a methodology showing how Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) could be integrated into the geotechnical design process. The presented methodology is then illustrated in a case study for assessing the climate impact and costs of high-speed railway embankment fill methods.
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| 17. |
- Samuelsson, Ida
(författare)
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LCA and LCCA in the design of geotechnical engineering works
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Geotechnical engineering works are part of almost all construction and infrastructure projects. The geotechnical engineering work contributes to the impact on the environment and gives rise to costs throughout its life cycle. Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) are established methods for evaluating a product's environmental impact and costs. However, the use of these methods is not extensive for geotechnical engineering works. A literature review showed that there is published research, but as the research topic is relatively new, there are many research gaps. A few topics in geotechnical engineering are better investigated than others and the entire life cycle is often not evaluated, usually only the production and construction stages. Although LCA and LCCA are established methods, the methodology for evaluating geotechnical engineering works needs further development to increase the evaluation work of sustainability aspects. In this licentiate thesis, a methodology is presented of how LCA and LCCA can be integrated into the geotechnical design process. The integration enables changes to the geotechnical design to further reduce the LCA and LCCA result, which is presented in the methodology. The methodology also presents a way to evaluate the possible geotechnical designs to select the most sustainable design based on the LCA and LCCA results. The thesis also presents the performance of LCA and LCCA for geotechnical engineering works and solutions to several difficulties that the geotechnical engineer may encounter during the evaluation of environmental impact and costs.
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| 18. |
- Samuelsson, Ida, et al.
(författare)
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Life cycle assessment and life cycle cost analysis for geotechnical engineering: review and research gaps
- 2021
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Ingår i: IOP Conference Series: Earth and Environmental Science. - Bristol : Institute of Physics Publishing (IOPP). - 1755-1307 .- 1755-1315.
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Konferensbidrag (refereegranskat)abstract
- Geotechnical engineering work contributes to the total environmental impact and monetary cost occurring from the construction sector. Decisions made regarding geotechnical engineering aspects have a profound effect on the environmental impact and the monetary cost of the structure during its life cycle. Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) are established methods for assessing the environmental impacts and monetary cost from construction works. This paper presents the results from a literature review of 56 published papers regarding the current situation of the use of LCA and LCCA methods in geotechnical engineering. It is found that only limited research has been published in applying LCA and LCCA to geotechnical engineering structures. Further research should focus on developing a framework using LCA and LCCA for geotechnical engineering structures and also identify and fill data gaps in computer software databases. This would help geotechnical engineers in their daily work to reduce the environmental impact and monetary costs throughout the life cycles of the designed structures.
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| 19. |
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| 20. |
- Spross, Johan, 1986-, et al.
(författare)
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Toward risk-based life cycle assessments in geotechnical design
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Following an increased focus on societal sustainability, life-cycle considerations have become more important for owners of geotechnical engineering structures. A structural design shall not only perform well at the completion of the structure, but facilitate structural performance over the whole service life. A sustainable geotechnical design should therefore strive to minimise the total life-cycle cost of the structure. As a consequence, the design needs to consider the effect of potential future hazards and allow for cost-effective maintenance.This report takes a first step toward risk-based life-cycle assessments in geotechnical design. The report reviews the current state of the art of probabilistic life-cycle assessments in civil engineering, with a focus on geotechnical design. Based on this, a probabilistic decision tool for geotechnical design from a life-cycle perspective is proposed. The applicability of the tool is then illustrated for a practical case, where different design alternatives for an embankment foundation on soft clay (vertical drains or dry deep mixing columns) are evaluated with respect to a potential groundwater drawdown event, occurring during the service life of the embankment. To facilitate this life-cycle cost assessment, novel reliability-based design methodologies were developed both for surcharges on vertical drains and for dry deep mixing columns. The research results are summarised in this final report and in six scientific articles, which have been appended.
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| 21. |
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| 22. |
- Strandkvist, Ida, et al.
(författare)
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Minimizing Chromium Leaching from Low-Alloy Electric Arc Furnace (EAF) Slag by Adjusting the Basicity and Cooling Rate to Control Brownmillerite Formation
- 2020
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 10:1, s. 35-50
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Tidskriftsartikel (refereegranskat)abstract
- Brownmillerite is connected to chromium leaching when present in steel slags. To prevent chromium leaching, brownmillerite in slag should be prevented. Two methods for decreasing brownmillerite content in low-alloy electric arc furnace (EAF) slag were investigated: decreasing the basicity and increasing the cooling rate. The methods were tried on both laboratory scale and in full-scale production. In the laboratory scale experiments, chromium leaching decreased as the basicity decreased until brownmillerite was no longer present, slower cooling resulted in increased chromium leaching, and faster cooling decreased chromium leaching. In full-scale production, basicity modified single batches, with a basicity below 2.2, generally leached less chromium than slag batches with higher basicity, thus verifying the correlation between basicity and chromium leaching seen in laboratory scale experiments. The cooling process in the full-scale experiments was achieved either by letting the slag cool by itself in the air or by water spraying. The water-sprayed slag, which cooled faster, had less chromium leaching than the air-cooled slag. The full-scale production experiments confirmed that both decreasing basicity below 2.2 and increasing the rate of cooling could be used to decrease chromium leaching.
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| 23. |
- Öhman, Marcus, et al.
(författare)
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Slag formation during combustion of biomass fuels
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Slag and ash deposition problems have more than occasionally been observed in biomass fueled plants in general and especially in pellet fired plants. These problems could lead to reduced accessibility as well as performance of the combustion appliances. Slag formation including measures for prevention and prediction during combustion of biomass fuels has been studied by the research groups at Luleå University of Technology, Umeå University, Energy Technology Center and Swedish University of Agricultural Sciences for about one decade know. Several (about 40) different biomass fuels/fuel mixtures have been studies and many different fuel additives/co-combustion fuels have been used to combat slag formation. About 25 scientific papers and 10 technical reports have been published by the research groups within the topic of slag formation during combustion of biomass fuels. The general experiences and conclusions of our research within the area will be presented.
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