| 1. |
- Björkman, Bo, et al.
(författare)
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Kinetics of Impurity Elimination During Roasting
- 1994
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Ingår i: Extraction and processing for the treatment and minimization of wastes, 1994. - Warrendale, Pa : Minerals, Metals & Materials Society. - 0873392612 ; , s. 825-842
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Konferensbidrag (refereegranskat)abstract
- Four different arsenic containing dusts from the Boliden plant, Boliden Mineral AB, Sweden have been examined. A kinetic study of the arsenic elimination was performed in a laboratory scale roasting furnace for roasting furnace ESP dust and smelting furnace ESP dust. Characterisation and thermodynamic calculations were carried out to determine the mineralogy, and the stability of compounds in the dusts studied. The characterisation methods used were chemical analysis, X-ray diffraction analysis and microprobe analysis. It was found in the experiments that a high degree of As elimination was obtained for roasting furnace ESP dust and a low degree for smelting furnace ESP dust. Derived kinetic models are given. A prediction of the As-elimination for settling furnace dust and converter ventilation dust is presented
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| 2. |
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| 3. |
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| 4. |
- Darreh-Shori, Taher, et al.
(författare)
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Functional variability in butyrylcholinesterase activity regulates intrathecal cytokine and astroglial biomarker profiles in patients with Alzheimer's disease
- 2013
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 34:11, s. 2465-2481
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Tidskriftsartikel (refereegranskat)abstract
- Butyrylcholinesterase (BuChE) activity is associated with activated astrocytes in Alzheimer's disease brain. The BuChE-K variant exhibits 30%-60% reduced acetylcholine (ACh) hydrolyzing capacity. Considering the increasing evidence of an immune-regulatory role of ACh, we investigated if genetic heterogeneity in BuChE affects cerebrospinal fluid (CSF) biomarkers of inflammation and cholinoceptive glial function. Alzheimer's disease patients (n = 179) were BCHE-K-genotyped. Proteomic and enzymatic analyses were performed on CSF and/or plasma. BuChE genotype was linked with differential CSF levels of glial fibrillary acidic protein, S100B, interleukin-1 beta, and tumor necrosis factor (TNF)-alpha. BCHE-K noncarriers displayed 100%-150% higher glial fibrillary acidic protein and 64%-110% higher S100B than BCHE-K carriers, who, in contrast, had 40%-80% higher interleukin-1b and 21%-27% higher TNF-alpha compared with noncarriers. A high level of CSF BuChE enzymatic phenotype also significantly correlated with higher CSF levels of astroglial markers and several factors of the innate complement system, but lower levels of proinflammatory cytokines. These individuals also displayed beneficial paraclinical and clinical findings, such as high cerebral glucose utilization, low beta-amyloid load, and less severe progression of clinical symptoms. In vitro analysis on human astrocytes confirmed the involvement of a regulated BuChE status in the astroglial responses to TNF-alpha and ACh. Histochemical analysis in a rat model of nerve injury-induced neuroinflammation, showed focal assembly of astroglial cells in proximity of BuChE-immunolabeled sites. In conclusion, these results suggest that BuChE enzymatic activity plays an important role in regulating intrinsic inflammation and activity of cholinoceptive glial cells and that this might be of clinical relevance. The dissociation between astroglial markers and inflammatory cytokines indicates that a proper activation and maintenance of astroglial function is a beneficial response, rather than a disease-driving mechanism. Further studies are needed to explore the therapeutic potential of manipulating BuChE activity or astroglial functional status. (C) 2013 Elsevier Inc. All rights reserved.
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| 5. |
- Eklund, Nicklas, et al.
(författare)
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Operation at High Pellet Ratio and Without External Slag Formers – Trials in an Experimental Blast Furnace
- 2009
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Ingår i: Steel Research International. - 1611-3683 .- 1869-344X. ; 80:6, s. 379-389, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- Blast furnaces that operate with pellets and sinter normally use high basicity sinter and acid pellets to balance the slag chemistry. When external additives are used, irregular slag formation occurs due to their uneven distribution in the burden. If basic sinter is used together with a large amount of acid pellets, all additives are incorporated in the iron bearing materials with an improved burden mixture as a consequence. During a campaign in the LKAB Experimental Blast Furnace, pellets and sinter were operated at an ultra low slag volume. A high amount of pellets was balanced with high basicity sinter. An improved blast furnace operation is shown when operating at ultra low slag volume and without external slag formers. During the test period, the blast furnace operation was smooth and stable, and the reductant rate was decreased.
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| 6. |
- Ma, Ping, et al.
(författare)
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Experimental and theoretical study of the removal of sulphur and fluorine from pickling hydroxide sludge generated in the stainless steel industry
- 2005
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Ingår i: Global Symposium on Recycling, Waste Treatment, and Clean Technology (REWAS '04). - : Minerals, Metals & Materials Society. - 8495520060 ; , s. 2017-2026
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Konferensbidrag (refereegranskat)abstract
- Pickling hydroxide sludge (pickling sludge for short) generated in the stainless steel industry in Sweden is currently dumped in special landfill areas. After filtration the sludge contains 50-60 wt-% moisture. After drying at 120C it contains about 26 wt-% of metal oxides, such as Fe 2O3, NiO and Cr2O3 and 43 wt-% of CaF2. In order to facilitate the recycling of pickling sludge and/or to recover fluorine as an HF acid, different scale experimental studies to remove sulphur and/or fluorine directly from the sludge have been carried out. Theoretical thermodynamic calculation results show that the simultaneous removal of both sulphur and fluorine is possible when the temperature is above 1500°C under the oxidizing condition and in the presence of water vapour in the system. Experimental results show that the elimination degrees of sulphur and fluorine for pickling sludge can reach 99 wt-% and 84 wt-%, respectively. These results demonstrate that potentially feasible methods for removing sulphur and/or fluorine from the sludge have been found.
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| 7. |
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| 8. |
- Nedar, Lotta, et al.
(författare)
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Mechanisms of dust formation in LD-converter : conclusions from characterization of dust and thermodynamic modelling of condensed compounds in the gas duct
- 1996
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Ingår i: 79th Steelmaking Conference proceedings. - Pittsburgh, Pa : Iron and Steel Society. - 1886362114 - 1886362122 ; , s. 755-762
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Konferensbidrag (refereegranskat)abstract
- To investigate the importance of the vaporization in the BOF process the vaporization from a steel bath was simulated together with the condensation of the resultant gas phase. An additional calculation was also made to simulate the condensation when the actual BOF dust composition was used. The course of condensation was investigated to determine the final products. The results from the calculation was compared with the results from hot gas sampling in the off gas system of a 100-t BOF. Four gas atmospheres were used to study the influence of the different oxygen potentials on the condensation reactions. Special emphasis was put on the condensation reactions of zinc. The results show the importance of the vaporization in the hot spot from which especially the elements having low vapour pressure will be vaporized. The increased oxygen potential will mostly influence the course of condensation but not very much the final products. The calculated condensation temperatures indicate a possible temperature span suitable for separation of zinc, alkali and chlorine gas from dust by gas treatment at high temperature in BOF. Dust are characterized by a complex mineralogical composition and especially the surface of the ejected metal and slag particles seem to be the nucleus for condensation and perhaps subsequent oxidation reactions
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| 9. |
- Ping, Ma, et al.
(författare)
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Experimental studies on solid-state reduction of pickling sludge generated in the stainless steel production
- 2005
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Ingår i: Scandinavian journal of metallurgy. - : Blackwell Publishing. - 0371-0459 .- 1600-0692. ; 34:1, s. 31-40
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Tidskriftsartikel (refereegranskat)abstract
- Neutralized pickling sludge generated during stainless steel production contains large amounts of calcium fluoride, water and a relatively low metal content, which makes it difficult to directly recycle back to the steelmaking process. It would also pose a potential environmental problem if deposited outdoors over a long term. However, metals such as iron, nickel and chromium, in the form of oxides and/or hydroxides, as well as calcium fluoride in the sludge, are of economic concern to stainless steel makers. Therefore, to develop an economically and technically suitable recycling process, a comparison study on reducing both pickling sludge and mixtures of metal oxides, using petroleum coke (P-coke) and graphite as reductant, respectively, was carried out at temperatures up to 1400°C using thermogravimetric (TG) analysis. Meanwhile, laboratory-scale tests on reducing pickling sludge, using P-coke as reductant, were also conducted in a Tammann fur nace at 800-1200°C. Results of the comparison study by TG demonstrate that the reduction behaviour of pickling sludge may be approached by the reduction behaviour of the metal oxide mixture having the same composition as those in the pickling sludge. Results of the Tammann furnace tests show that temperature has a significant influence on reduction. The reduced metals in the reduction products exist mostly in the form of alloys such as '(Fe,Ni)' and 'Cr-Fe-Ni'.
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| 10. |
- Ping, Ma, et al.
(författare)
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Mechanism study on solid-state reduction in the Fe2O3–NiO–Cr2O3–C system using thermal analyses
- 2005
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Ingår i: Scandinavian journal of metallurgy. - : Blackwell Publishing. - 0371-0459 .- 1600-0692. ; 34:1, s. 22-30
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Tidskriftsartikel (refereegranskat)abstract
- In order to clarify the interactions among metal oxides during reduction of pickling sludge, the reduction mechanism of the metal oxide mixture, Fe2O3-NiO-Cr2O3, which simulates the composition of these metal oxides in pickling sludge, was studied using graphite as a reductant, by means of thermal analysis techniques. X-ray diffraction analysis was used for characterization of reduction products. In addition to the reduction test on the metal oxide mixture mentioned above, for comparison, separate tests on the reduction of Fe2O3, NiO and Cr2O3 were also conducted. The results demonstrate that through formation of a transitional compound 'FeCr2O4', Fe2O3 promotes the complete reduction of Cr 2O3 at a temperature lower than that required for reducing pure Cr2O3. On the other hand, Cr2O3 hinders the reduction of Fe2O3 at lower temperatures. The whole reduction process may be classified as five distinguishable reduction stages in which possible reactions were proposed to represent the reduction mechanism. The reduced metals in the final product exist primarily in the form of solid solutions, such as 'Cr-Fe-Ni', which mainly containing '(Fe,Ni)' and '(Fe,Cr)', and small amounts of carbides, such as (Cr,Fe)7C3 and/or Cr7C3.
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