| 1. |
- Hu, Xianfeng
(författare)
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Studies on Carbothermic Reduction of Chromite in the Presence of FeOx
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Direct chromium alloying by chromite ore is a promising technology for producing Crcontainingsteels, as the ferrochrome production process and the chromium alloying processare integrated into a single step, which has the potential of saving energy and raw materials.In this work Thermogravimetric Analysis experiments and induction furnace experiments (upto 80-kg scale) have been carried out to investigate the carbothermic reduction process ofchromite in the presence of FeOx (iron, mill scale or magnetite). The aims are to investigatethe effect of FeOx on the carbothermic reduction of chromite and to explore the potential ofdirectly alloying steel with chromium by the designed alloying precursor ‘chromite ore +FeOx + carbonaceous material’.The results from the Thermogravimetric Analysis experiments show that FeOx can enhancethe carbothermic reduction of chromite and the enhancing effect increases when increasedamounts of FeOx are added to the chromite. The enhancing effect is attributed to the presenceof added metallic iron or the metallic iron reduced from mill scale or magnetite, which candecrease the activity of chromium by having chromium dissolve in the iron in situ. The resultsfrom the induction furnace experiments show that the steel can be directly alloyed withchromium by using the designed alloying precursor ‘chromite ore + mill scale + petroleumcoke’ and the chromium yield from chromite ore increases when increased amounts of millscale are added to the alloying precursor.The designed alloying precursor, on one hand, can be potentially used to directly alloy steelwith chromium in the Electric Arc Furnace steelmaking process and, on the other hand, can bepotentially used to produce Cr pre-alloyed iron powder or Cr pre-alloyed Direct Reduced Ironby the solid-state reduction process. The proposed applications have the potential to improvethe raw materials efficiency and energy efficiency.
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| 2. |
- Karhu, Marjaana, et al.
(författare)
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D4.3 Circular Economy and zero waste aspects and business models of production
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This deliverable reports the survey done in SCRREEN project in Task 4.3 relating to environmental trends and CircularEconomy (CE) aspects of CRM production. For each CRM, the Circular Economy aspects were addressed in order to identifythe gaps that limit performance of the processing chains, hinder closing the loop and hinder a zero-waste CRM production.Information on processes, production, solutions and eco-design principles for closing the loop of raw materials in order tosupport the zero-waste point-of-view, resource efficiency and energy efficiency simultaneously were gathered. In addition, theaspects supporting Circular Economy were evaluated trying to resolve the identified challenges. Lastly, the environmentalissues e.g. toxicity related to CRMs production were reviewed.
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| 3. |
- Liu, Yuhuai, et al.
(författare)
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Microplastics in soil can increase nutrient uptake by wheat
- 2022
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894. ; 438
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Tidskriftsartikel (refereegranskat)abstract
- Microplastics can perturb microbial nutrient-mining strategies. However, the mechanism by which microplastics affect the resource-acquisition strategies of crops in agricultural systems remains unknown. The nutrient-acquisition potential of crops and microbes was investigated under treatments with two common microplastics (polyethylene [PE] and polyvinyl chloride [PVC]) at 0%, 1%, and 5% (w/w). Different root resource-acquisition strategies disturbed microbial nutrient turnover in the rhizosphere in response to microplastic addition. Specifically, the β-1,4-glucosidase (BG) hotspot expanded, whereas the rhizosphere expansion of BG activity decreased. A decrease of less than PE1% (w/w) and an expansion of less than PE5% (w/w) in the 1,4-N-acetyl-glucosaminidase (NAG) hotspot with wider rhizosphere expansion of NAG activity indicated that higher doses of PE allow roots to uptake additional N. The phosphomonoesterase (PHOS) hotspot decreased in PE1% (w/w) and expanded in PE5% (w/w), but rhizosphere expansion did not change under PE treatments. However, both NAG and PHOS hotspots expanded with decreasing rhizosphere expansion under PVC treatments, indicating that PVC limits the utilization of available N and P, forcing the crop to obtain nutrients from the narrow root zone. These results indicate that adding PE microplastics increases the demand for and consumption of NH4+-N and NO3--N by wheat.
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| 4. |
- McCoy, Isabel L., et al.
(författare)
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The hemispheric contrast in cloud microphysical properties constrains aerosol forcing
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:32, s. 18998-19006
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Tidskriftsartikel (refereegranskat)abstract
- The change in planetary albedo due to aerosol-cloud interactions during the industrial era is the leading source of uncertainty in inferring Earth's climate sensitivity to increased greenhouse gases from the historical record. The variable that controls aerosol-cloud interactions in warm clouds is droplet number concentration. Global climate models demonstrate that the present-day hemispheric contrast in cloud droplet number concentration between the pristine Southern Hemisphere and the polluted Northern Hemisphere oceans can be used as a proxy for anthropogenically driven change in cloud droplet number concentration. Remotely sensed estimates constrain this change in droplet number concentration to be between 8 cm(-3) and 24 cm(-3). By extension, the radiative forcing since 1850 from aerosol-cloud interactions is constrained to be -1.2 W.m(-2) to -0.6 W.m(-2). The robustness of this constraint depends upon the assumption that pristine Southern Ocean droplet number concentration is a suitable proxy for preindustrial concentrations. Droplet number concentrations calculated from satellite data over the Southern Ocean are high in austral summer. Near Antarctica, they reach values typical of Northern Hemisphere polluted outflows. These concentrations are found to agree with several in situ datasets. In contrast, climate models show systematic underpredictions of cloud droplet number concentration across the Southern Ocean. Near Antarctica, where precipitation sinks of aerosol are small, the underestimation by climate models is particularly large. This motivates the need for detailed process studies of aerosol production and aerosol-cloud interactions in pristine environments. The hemispheric difference in satellite estimated cloud droplet number concentration implies preindustrial aerosol concentrations were higher than estimated by most models.
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