| 1. |
- Pei, Benyan, et al.
(författare)
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A thermodynamic assessment of the iron - Antimony system
- 1995
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Ingår i: Calphad. - 0364-5916 .- 1873-2984. ; 19:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- A critical assessment of the Fe-Sb system was carried out by using a computerized technique. Both the liquid and solid solution phases were described by regular solution models. Nonstoichiometric phase, ε-FeSb, was modeled as (Fe)(Fe,Sb), and FeSb2 was treated as a stoichiometric compound. A set of parameters describing the Gibbs energies of the different phases was optimized by using the existing phase diagram information and thermodynamic properties under one atmosphere. Assessed phase diagram and thermodynamic data are presented and compared with experimental data.
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| 2. |
- Pei, Benyan, et al.
(författare)
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Thermodynamic assessment of the Cu-As system using an ionic two-sublattice model for the liquid phase
- 1994
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Ingår i: Zeitschrift für Metallkunde. - 0044-3093. ; 85:3, s. 178-184
-
Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic properties and phase relations in the system Cu-As were assessed. The liquid phase was described using an ionic two-sublattice model. The terminal FCC copper solution was represented by a substitutional regular solution model. The nonstoichiometric phase, γ (Cu3As), was treated by a two-sublattice model, (Cu, Va)3As, with vacancies on the Cu sublattice. The other two intermetallic compounds, β (Cu 8As) and δ (Cu12As5), were treated as stoichiometric phases. A consistent set of thermodynamic parameters was derived using activity data and phase diagram information from the literature. Various thermodynamic properties and the phase diagram were calculated from the parameters. The calculated phase equilibria and activities of arsenic and copper in the liquid phase agree very well with the literature data.
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| 3. |
- Pei, Benyan, et al.
(författare)
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Thermodynamic assessment of the Fe-As system using an ionic two-sublattice model for the liquid phase
- 1994
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Ingår i: Zeitschrift für Metallkunde. - 0044-3093. ; 85:3, s. 171-177
-
Tidskriftsartikel (refereegranskat)abstract
- The phase diagram and thermodynamic data of the Fe-As system were critically assessed. Activities in the liquid phase and phase diagram information were used in the assessment. The liquid phase was represented by an ionic two-sublattice model. The terminal BCC and FCC solid solutions of arsenic in iron were described by a substitutional regular solution model. The nonstoichiometric compound, Fe3As2, was treated by a two-sublattice model, Fe(As, Va)0.75, with vacancies on the As sublattice. The other intermetallic compounds, Fe2As, FeAs, and FeAs2 were all considered as stoichiometric. Based on the assessed thermodynamic model parameters, the thermodynamic properties and the phase diagram were calculated and discussed. The calculated phase equilibria and component activities of the liquid phase agree very well with literature data.
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| 4. |
- 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
-
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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| 5. |
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| 6. |
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| 7. |
- Eklund, Nicklas, et al.
(författare)
-
Operation at High Pellet Ratio and Without External Slag Formers – Trials in an Experimental Blast Furnace
- 2009
-
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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| 8. |
- Eriksson, Johan, et al.
(författare)
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Utilisation of oily mill scale sludge as scrap resource
- 1999
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Ingår i: REWAS '99. ; , s. 1423-1430
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the results of reduction trials of oily mill scale sludge. Laboratory experiments and two campaigns in a pilot plant rotary kiln have been carried out. The results indicate that it's possible to reduce oily mill scale sludge to sponge iron in the rotary kiln. The first pilot plant campaign was carried out with a mix of 75 wt-% mill scales and 25 wt-% mill scale sludge. During the second campaign 100 wt-% oily mill scale sludge were mixed with blast furnace flue dust and reduced. Petroleum coke has been used as the main reductant in both campaigns. Smelting trials of the sponge iron product have also been carried out in a production EAF. The sponge iron was charged into the scrap bin in big-bags. These trials showed that the degree of metallization of the sponge iron must be higher than 55% to avoid an increased iron oxide content in the slag, i.e. a low iron yield to the metal
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| 9. |
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| 10. |
- 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
-
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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| 11. |
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| 12. |
- 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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| 13. |
- 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
-
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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| 14. |
- 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
-
Ingår i: Scandinavian journal of metallurgy. - : Blackwell Publishing. - 0371-0459 .- 1600-0692. ; 34:1, s. 22-30
-
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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| 15. |
- Prevéy, Janet S., et al.
(författare)
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The tundra phenology database: more than two decades of tundra phenology responses to climate change
- 2022
-
Ingår i: Arctic Science. - : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 1026-1039
-
Tidskriftsartikel (refereegranskat)abstract
- Observations of changes in phenology have provided some of the strongest signals of the effects of climate change on terrestrial ecosystems. The International Tundra Experiment (ITEX), initiated in the early 1990s, established a common protocol to measure plant phenology in tundra study areas across the globe. Today, this valuable collec-tion of phenology measurements depicts the responses of plants at the colder extremes of our planet to experimental and ambient changes in temperature over the past decades. The database contains 150 434 phenology observations of 278 plant species taken at 28 study areas for periods of 1–26 years. Here we describe the full data set to increase the visibility and use of these data in global analyses and to invite phenology data contributions from underrepresented tundra locations. Portions of this tundra phenology database have been used in three recent syntheses, some data sets are expanded, others are from entirely new study areas, and the entirety of these data are now available at the Polar Data Catalogue (https://doi.org/10.21963/13215).
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| 16. |
- Yang, Fangkai, et al.
(författare)
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Diffusion-Based Time Series Data Imputation for Cloud Failure Prediction at Microsoft 365
- 2023
-
Ingår i: ESEC/FSE 2023 - Proceedings of the 31st ACM Joint Meeting European Software Engineering Conference and Symposium on the Foundations of Software Engineering. - : Association for Computing Machinery (ACM). ; , s. 2050-2055
-
Konferensbidrag (refereegranskat)abstract
- Ensuring reliability in large-scale cloud systems like Microsoft 365 is crucial. Cloud failures, such as disk and node failure, threaten service reliability, causing service interruptions and financial loss. Existing works focus on failure prediction and proactively taking action before failures happen. However, they suffer from poor data quality, like data missing in model training and prediction, which limits performance. In this paper, we focus on enhancing data quality through data imputation by the proposed Diffusion+, a sample-efficient diffusion model, to impute the missing data efficiently conditioned on the observed data. Experiments with industrial datasets and application practice show that our model contributes to improving the performance of downstream failure prediction.
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| 17. |
- Adolfsson, Daniel, et al.
(författare)
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Cementitious phases in ladle slag
- 2011
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:4, s. 398-403
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Tidskriftsartikel (refereegranskat)abstract
- Ladle slag is an internal by-product generated within the steelmaking industry during the refining of steel. The realisation of beneficial inherent properties of ladle slag as a binder supplement or substitute material is believed to be advantageous with respect to both economy and environment for steelmakers. For this reason, the current study has focused on highlighting the properties of ladle slag that are pertinent to the formation of calcium aluminate hydrates. Three fractions of ladle slag, two of which were based on different slag formers, have been characterised using XRF, XRD and calorimetric analysis. Commonly known hydraulic minerals such as mayenite, tricalcium aluminate and dicalcium silicate were detected during analysis. An important aspect in the utilisation of ladle slag is the slag handling methodology. Therefore, this study also highlights and discusses the need to reconsider slag handling procedures concerning unnecessary exposure to weathering and the possible need for further processing of the slag in order to better employ the inherent hydraulic properties of this material.
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| 18. |
- Adolfsson, Daniel, et al.
(författare)
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Hydraulic properties of sulphoaluminate belite cement based on steelmaking slags
- 2007
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Ingår i: Advances in Cement Research. - : Thomas Telford Ltd.. - 0951-7197 .- 1751-7605. ; 19:3, s. 133-138
-
Tidskriftsartikel (refereegranskat)abstract
- Based on modified Bogue calculations, steelmaking slags were combined in order to produce a belite-rich clinker activated with sulphoaluminate. The experiments were conducted on two different mixtures based on steelmaking slags together with additives, namely MixA and MixB. The objective of the present study was to investigate the hydraulic properties of the specimens, using conduction calorimetry, X-ray diffraction and differential scanning calorimetry, and also to measure the mechanical strength of the specimens when hydrated for 2 and 28 days. The compressive strength was satisfactory in relation to the estimated compositions. Both mixtures behaved the same with regard to heat development as well as the amount of ettringite formed during the first 24 h of the hydration.
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| 19. |
- Adolfsson, Daniel, et al.
(författare)
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Influence of mineralogy on the hydraulic properties of ladle slag
- 2011
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846 .- 1873-3948. ; 41:8, s. 865-871
-
Tidskriftsartikel (refereegranskat)abstract
- The present study is aimed at investigating the hydraulic characteristics of ladle furnace slag (LFS), under the pretence of using LFS as a cement substitute in certain applications. Furthermore, LFS has been considered as a possible activator in a blend containing 50% LFS, and 50% ground granulated blast furnace slag (GGBFS). Phases detected in LFS were quantified using Rietveld analysis. Calorimetric studies were performed at 20, 25 and 30 °C in order to calculate the apparent activation energy of hydration and thereby to suggest a kinetic model for the tested compositions within this temperature interval. In addition, compressive strength tests were performed on mortar prisms made with LFS, and LFS/GGBFS which had hydrated for 2, 7 and 28 days. Both compositions reached acceptable early strengths, (e.g. LFS, 33.1 MPa, and LFS/GGBFS, 17.9 MPa, after 2 days), but after 28 days hydration the blend was superior to neat LFS. Related apparent activation energies were determined using an Avrami–Erofeev model and gave Ea = 58 kJ/mol for neat LFS and Ea = 63 kJ/mol for the blend. The results imply that LFS or a LFS/GGBFS blend can be favourably used as supplement in binder applications such as binder in by-product metallurgical briquettes, which are used as recycle to the blast furnace or basic oxygen furnace depending on the specific briquette composition.
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| 20. |
- Adolfsson, Daniel, et al.
(författare)
-
Steelmaking slags as raw material for sulphoaluminate belite cement
- 2007
-
Ingår i: Advances in Cement Research. - : Thomas Telford Ltd.. - 0951-7197 .- 1751-7605. ; 19:4, s. 147-156
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, slags from the steelmaking industry are described and considered as a potential raw material within the field of sulphoaluminate belite cement. The objective of the study was to investigate the possibility of using a substantial amount of steelmaking slags as raw meal in the manufacture of a sulphobelitic clinker. A further aim was to compare the influence of different slags in relation to the formation of sulphoaluminate and the other clinker phases required. The behaviour of high temperature reactions was investigated by using thermogravimetric analysis coupled with a quadrupole mass spectrometer. Mineralogical observations were carried out through X-ray powder diffraction, and scanning electron microscopy. Three different mixtures and a single ladle slag were prepared using modified Bogue calculations, which are characterised by the assessment of a potential phase composition in order to produce belite-rich cement activated with sulphoaluminate. The results so far prove that steelmaking slags have the potential to be used as raw material, since sulphoaluminate along with polymorphs of dicalcium silicate and ferrite phases were detected after firing at 1200 degrees C in an air atmosphere.
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| 21. |
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| 22. |
- Ahmed, Hesham, et al.
(författare)
-
Alternative Reducing Agents for Sustainable Blast Furnace Ironmaking
- 2017
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Ingår i: ESTAD 2017.
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Konferensbidrag (refereegranskat)abstract
- Lowering of CO2 emission from the integrated steel industry as well as minimizing theneed for landfill are important challenges in the focus for the integrated steel industry. With thisaim collaborative research projects have been conducted and are on-going on the possible useof renewable reducing agents or such with high content of H2 as well as for enabling recyclingof 1in-plant fines so far not possible to use. Due to contents of undesired impurities the blastfurnace (BF) sludge has to be pre-treated in an appropriate way before carbon and iron oxidecan be valorized. In order to understand the impact of alternative reducing agents as injectedthrough the tuyeres or part of top charged agglomerates containing iron oxide, samples oftorrefied biomass, plastic and in-plant fines have been analyzed by means of thermogravimetricanalyzer coupled with a mass spectrometer (TGA-MS).The results proved that effective utilization of carbon bearing BF dust and sludge as analternate reducing agent could be realized and can be implemented into BF after adequateupgrading. Plastic materials and biomass based reductants decomposition is associated with therelease of volatiles. The main contents of these volatiles are CO, H2 and hydrocarbon which areall known for their reduction potential. Moreover, injection of such materials is expected toimprove process efficiency and sustain the gas permeability along the BF cohesive zone. Onthe other hand, top charging of these materials would improve the energy and materialefficiency in the BF due to their higher reactivity compared to conventional carbon.
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| 23. |
- Ahmed, Hesham, et al.
(författare)
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Composite Pellets – A Potential Raw Material for Iron-Making
- 2014
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:3, s. 293-306
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Forskningsöversikt (refereegranskat)abstract
- Coke constitutes the major portion of iron-making cost and its production causes severe environmental concerns. In addition, lower energy consumption, lower CO2 emission and waste recycling are driving the Iron and steel making industry to develop “coke free, zero waste or green processes”. In the present article, an overview of possible ways to recognize a reasonable improvement in iron and steel making industry is summarized. The present discussion is focusing on the following approaches: 1. Replacing expensive coke with relatively less expensive alternate fuels having carbon as well as significant amount of hydrogen such as coal, waste plastic and biomass materials.2. Producing agglomerates from cheaper raw materials (secondary resources) as well as improving their performance in BF.3.Making the process towards higher carbon utilization by shifting the wustite equilibrium towards lower CO/CO2 ratio by using high reactive coke or catalytic activated one.4.Recycling the unused CO in the top gas by removing CO2 from the gas stream.Much attention has been paid to carbon composite agglomerates (CCA) as a promising raw material for future iron making. Production, mechanical and chemical suitability, reduction behavior, etc. are being elaborated. In addition, other possible ways to utilize CCA in alternate iron-making process has been explored.
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| 24. |
- Ahmed, Hesham, et al.
(författare)
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Effect of added olivine on iron ore agglomerate during induration
- 2018
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Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 58:3, s. 446-452
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Tidskriftsartikel (refereegranskat)abstract
- Olivine is used extensively in iron-pellet production as an additive in LKAB blast furnace pellets, in order to improve the high temperature properties of the finished product during reduction. As the contribution of olivine into the process depends on the available surface area, the present study was designed to find out the effect of olivine and its fineness on the oxidation-sintering and subsequent dissociation of olivine in iron ore agglomerates. Agglomerates were exposed to different experimental conditions to study the effect of olivine on the behavior of magnetite and hematite at high temperatures. Olivine particles were found to react significantly only above 1 000°C. Porosity of the final product was found to depend largely on olivine fineness. The finer the olivine the lower the porosity of the final product. It is found also that irrespective of the starting iron oxide the ratio between hematite and spinel phase was the same after heating in air. Olivine fineness affects significantly the rate of hematite dissociation, the finer the olivine the higher the dissociation rate. Upon cooling the weight lost due to the dissociation was again regained
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| 25. |
- Ahmed, Hesham, et al.
(författare)
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Effect of carbon concentration and carbon bonding type on the melting characteristics of hydrogen- reduced iron ore pellets
- 2022
-
Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 21, s. 1760-1769
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Tidskriftsartikel (refereegranskat)abstract
- Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuel-based reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today's operations. In addition to carbon being an alloying element in steel production, carbon addition controls the melting characteristics of the reduced iron. In the present study, the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content 2 wt%, the molten fraction is higher in the case of carburized samples, which is indicated by the amount of absorbed melting heat.
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| 26. |
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| 27. |
- Ahmed, Hesham, et al.
(författare)
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Effect of the Ash from H2‐Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity
- 2020
-
Ingår i: Steel Research International. - : John Wiley & Sons. - 1611-3683 .- 1869-344X. ; 91:11
-
Tidskriftsartikel (refereegranskat)abstract
- The iron and steel industry is one of the most important sectors worldwide, and it has a great impact on the global economy; however, this sector is still highly dependent on fossil carbon. To decrease this dependency, approaches to partially replace the injected pulverized coal with secondary, highly reactive, renewable (biomass) and H2‐rich materials have been studied. The injection of such materials is expected to significantly decrease the emitted CO2 from blast furnaces. However, due to the different ash composition of these alternative materials (especially alkali and alkaline earth metals) compared to that of ordinary injected coal, these materials are expected to alter the raceway slag properties and affect the coke reactivity. In the present article, the effect of the ash from different hydrogen‐rich carbonaceous materials on the raceway slag physicochemical properties as well as coke reactivity is reported. The melting characteristics of the ash briquettes in contact with the coke and wettability of the melted ash on the coke surface are determined visually using an optical heating microscope. The effect of the ash on the coke reactivity is studied by means of thermogravimetry under a continuous flow of CO2.
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| 28. |
- Ahmed, Hesham, et al.
(författare)
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Energy Efficient Recycling of in-Plant Fines
- 2014
-
Ingår i: Proceedings of World Academy of Science, Engineering and Technology. - 2010-376X .- 2070-3740. ; 8:6, s. 485-491
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Tidskriftsartikel (refereegranskat)abstract
- Numerous amounts of metallurgical dusts and sludge containing iron as well as some other valuable elements such as Zn, Pb and C are annually produced in the steelmaking industry. These alternative iron ore resources (fines) with unsatisfying physical and metallurgical properties are difficult to recycle. However, agglomerating these fines to be further used as a feed stock for existing iron and steelmaking processes is practiced successfully at several plants but for limited extent.In the present study, briquettes of integrated steelmaking industry waste materials (namely, BF-dust and sludge, BOF-dust and sludge) were used as feed stock to produce direct reduced iron (DRI). Physical and metallurgical properties of produced briquettes were investigated by means of TGA/DTA/QMS in combination with XRD. Swelling, softening and melting behavior were also studied using heating microscope.
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| 29. |
- Ahmed, Hesham, et al.
(författare)
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Injection of H2-rich carbonaceous materials into the blast furnace : devolatilization, gasification and combustion characteristics and effect of increased H2–H2O on iron ore pellets reducibility
- 2020
-
Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 9:6, s. 16029-16037
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Tidskriftsartikel (refereegranskat)abstract
- Increasing the share of hydrogen in reduction of iron oxide in the blast furnace iron making will directly reduce the share of blast furnace greenhouse gas emissions. In the present study, injection of H2-rich biomass and plastic materials was studied in terms of its devolatilization, gasification and combustion characteristics. The released gases were identified using mass spectroscopy attached to a thermogravimetric analyzer and the corresponding kinetics parameters were estimated.The devolatilization was found to occur through two or more steps. The first step is always associated with the release of CO2, CO, H2, H2O and hydrocarbons while only CO and H2 were detected during the later steps. Combustion and gasification starting temperatures of char of H2-rich carbonaceous materials were lower than that of pulverized coal char by ≥ 100 °C. The estimated activation energies suggested that, under the present conditions, devolatilization, gasification and combustion were chemically controlled. Carbon reactivity of the char of the studied H2-rich carbonaceous materials were higher than that of pulverized coal. Moreover, increased H2–H2O content in the blast furnace gas, due to injected H2-rich carbonaceous materials, was found to improve the iron ore pellets reduction kinetics.
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| 30. |
- Ahmed, Hesham, et al.
(författare)
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Isothermal reduction kinetics of self-reducing mixtures
- 2017
-
Ingår i: Ironmaking & steelmaking. - : Taylor & Francis. - 0301-9233 .- 1743-2812. ; 44:1, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Isothermal reduction of haematite carbon mixtures was investigated at temperatures 750–1100°C under inert atmosphere. Mass loss curves proved the stepwise reduction of haematite to metallic iron. The non-linear feature of haematite to magnetite reduction kinetics was observed and an activation energy of 209 kJ mol−1 was calculated. Irrespective of carbon-bearing material type, reduction rate of magnetite was linear. Activation energy values were calculated to be 293–418 kJ mol−1. Significant increase in the reduction kinetics in the last step (Wustite reduction) was observed and explained by the catalytic effect of freshly formed metallic iron. During the initial stages of wustite reduction, the activation energy values were calculated to be in the range of 251–335 kJ mol−1 for all carbon-bearing materials.
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| 31. |
- Ahmed, Hesham, et al.
(författare)
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Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere
- 2015
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Ingår i: ISIJ International. - 0915-1559 .- 1347-5460. ; 55:10, s. 2082-2089
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Tidskriftsartikel (refereegranskat)abstract
- Large amount of dust and sludge recovered during cleaning of iron and steel making process gases are annually put on landfill or intermediate storage. These by-products have high contents of iron (Fe) and carbon (C) that potentially could be utilized in the steel industry. However, due to the presence of impuritycompounds as well as the unsuitable physical properties, these by-products cannot be recycled directly. The main objective of the present study is to investigate the possibilities to recover the valuable components Fe and C in these by-products and thereby decrease the need of landfills at the steel plants as well as reduce the consumption of virgin materials, including fossil coal, and reduce CO2 emissions. A recycling route has been investigated by means of laboratory trials and FactSage thermodynamic modeling. Four different blends of BF and BOF dusts and sludges are prepared in predetermined ratios. Reduction behavior of each blend is studied using TG/DTA/QMS and in-situ high temperature X-ray diffraction. High temperature physical properties like softening, swelling and melting are also investigated by means of heatingmicroscope. The obtained results indicate the feasibility of both minimizing the impurity elements as well as recovering of valuable components.
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| 32. |
- Ahmed, Hesham, et al.
(författare)
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Utilization of Steelmaking Industry Waste Materials in Producing Direct Reduced Iron
- 2014
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Konferensbidrag (refereegranskat)abstract
- The depletion of coke reserves and the raised environmental concerns motivated researchers to work on alternative iron-making processes. Large amount of metallurgical dusts and sludge containing iron and C are produced in the steelmaking industry. These alternative iron ore resources (fines) with poor hydrophilicity are difficult to recycle. The idea of briquetting such wastes containing iron to be used as a feed stock for steelmaking industry is practiced successfully at several plants.In the present study, agglomerates of integrated steelmaking industry waste materials were used as feed stock to produce direct reduced iron (DRI). The reduction behavior of blends of different waste materials (namely, BF dust and sludge, BOF dust and sludge) were investigated thoroughly utilizing TGA/DTA/QMS in combination with XRD.
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| 33. |
- Albertsson, Galina, et al.
(författare)
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Effect of Low Oxygen Partial Pressure on the Chromium Partition in CaO-MgO-SiO2-Cr2O3-Al2O3 Synthetic Slag at Elevated Temperatures
- 2013
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Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:7, s. 670-679
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the present work is to get an understanding of the impact of Al2O3 addition on the phase relationships in the CaO-MgO-Al2O3-SiO2-Cr2O3 slags at low oxygen partial pressures (P-O2 = 10(-4) Pa), with a view to control the precipitation of Cr-spinel in the slag. The equilibrium phases in CaO-MgO-Al2O3-SiO2-Cr2O3 slag system in the range on 1673-1873 K have been investigated. The compositions close to the industrial slag systems were chosen. The Cr2O3 content was fixed at 6 wt% and MgO at 8 wt%. Al2O3 contents in the slag were varied in the range of 3-12 wt%. The basicity (CaO/SiO2) of slag was set to 1.6. Gas/slag equilibrium technique was adopted. The samples were heated to 1873 K and soaked at this temperature for 24 h. The samples were then slow cooled to 1673 K and equilibrated for an additional 24 h. The oxygen partial pressure was kept at 10(-4) Pa. A gas mixture of CO/CO2 was used to control the oxygen partial pressure. After the equilibration, the samples were quenched in water. The chromium distribution and phase compositions in the quenched slags were studied using SEM-WDS and XRD techniques. The results were compared with the phase equilibrium calculations obtained from FACTSAGE software and the samples equilibrated in air. The size of spinel crystals increased drastically after slow cooling followed by annealing compared to samples being quenched after soaking at 1873 K. It was also found that low oxygen partial pressure had a strong impact on chromium partition. The amount of spinel phase increases with increased Al2O3 content.
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| 34. |
- Andersch-Björkman, Ylva, et al.
(författare)
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Air-oxidized linalool elicits eczema in allergic patients-a repeated open application test study.
- 2014
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Ingår i: Contact dermatitis. - : Wiley. - 1600-0536 .- 0105-1873. ; 70:3, s. 129-38
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Tidskriftsartikel (refereegranskat)abstract
- Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%. No elicitation studies have been performed.
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| 35. |
- Andersson, Anton, et al.
(författare)
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A holistic and experimentally-based view on recycling of off-gas dust within the integrated steel plant
- 2018
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Ingår i: Metals. - Basel : MDPI AG. - 2075-4701. ; 8:10
-
Tidskriftsartikel (refereegranskat)abstract
- Ore-based ironmaking generates a variety of residues, including slags and fines such as dust and sludges. Recycling of these residues within the integrated steel plant or in other applications is essential from a raw-material efficiency perspective. The main recycling route of off-gas dust is to the blast furnace (BF) via sinter, cold-bonded briquettes and tuyere injection. However, solely relying on the BF for recycling implicates that certain residues cannot be recycled in order to avoid build-up of unwanted elements, such as zinc. By introducing a holistic view on recycling where recycling via other process routes, such as the desulfurization (deS) station and the basic oxygen furnace (BOF), landfilling can be avoided. In the present study, process integration analyses were utilized to determine the most efficient recycling routes for off-gas dust that are currently not recycled within the integrated steel plants of Sweden. The feasibility of recycling was studied in experiments conducted in laboratory, pilot, and full-scale trials in the BF, deS station, and BOF. The process integration analyses suggested that recycling to the BF should be maximized before considering the deS station and BOF. The experiments indicated that the amount of residue that are not recycled could be minimized.
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| 36. |
- Andersson, Anton, et al.
(författare)
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Characterization and Upgrading of a Low Zinc-Containing and Fine Blast Furnace Sludge : A Multi-Objective Analysis
- 2017
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Ingår i: ISIJ International. - : The Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 57:2, s. 262-271
-
Tidskriftsartikel (refereegranskat)abstract
- Ore-based steelmaking generates a variety of residues including dusts, sludges and slags. Recycling of these residues within the process or via other applications is essential for sustainable production from both environmental and economic aspects. In blast furnace (BF) ironmaking, there are generally two residues leaving the gas cleaning equipment; namely, BF dust and BF sludge. Traditionally, the dust is recycled via the sinter or, in the case of pellet based BF, via cold bonded agglomerates and injection. As the main output of zinc from the BF is the top gas, the sludge has to be dezinced prior to recycling to prevent accumulation of zinc in the furnace. Although dezincing of BF sludge has been successfully accomplished using e.g., hydrocycloning, the studied sludges are generally coarse sized and high in zinc. Furthermore, information is lacking regarding the efficiency of separation of different hydrocyclone setups. In the present work, hydrocycloning of a fine sludge, with low zinc content, generated by a pellet based BF has been studied. The gas cleaning equipment used to produce the sludge was running a primary aerocyclone and a scrubber. A characterization of the sludge has been conducted together with an evaluation of the separation efficiency of the hydrocyclone in order to assess the hydrocyclone performance and limitations. Furthermore, the dezincing using the hydrocyclone has been compared to that of sulfuric acid leaching. The results suggest that 51 to 93% of the sludge can be recycled depending on the demand on zinc removal and the chosen dezincing route.
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| 37. |
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| 38. |
- Andersson, Anton, et al.
(författare)
-
Characterization of Blast Furnace Sludge and Upgrading Using Physical Separation and Leaching
- 2017
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Konferensbidrag (refereegranskat)abstract
- The on-site sinter plants of the Swedish ore based steel industry are all closed. Instead of using sinter, the blast furnaces (BF) operate on iron ore pellets and the major part of the recycling of in-plant residues is realized via cold bonded briquettes charged to the BF. Cost of raw materials and energy continuously drives the work towards an increased recycling of in plant residues. The major part of the zinc entering the BF leaves through the top gas ending up in the BF dust and sludge. The recycling of all the BF dust back to the BF leaves the BF sludge as the main bleed of zinc out of the system. In order to utilize the iron and carbon content of the sludge, means to remove zinc is required prior to recycling via the briquette. In the present work, blast furnace sludge has been characterized. Using the characterization as standpoint, different operations for zinc removal was suggested and studied in laboratory scale. Zinc was successfully removed using a hydrometallurgical and physical separation route, respectively. A successful dezincing operation would enable the recycling of the sludge. This would improve the material- and energy efficiency and substantially decrease the amount of sludge being landfilled.
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| 39. |
- Andersson, Anton, et al.
(författare)
-
Evaluation of evaporation kinetics of potassium from synthetic blast furnace slag using full factorial design of experiments
- 2021
-
Konferensbidrag (refereegranskat)abstract
- In the present work, a full factorial design of experiments with three factors was performed studying the evaporation of potassium (K) from synthetic blast furnace (BF) slag. The experiments showed that slag temperature and B2 basicity (%CaO/%SiO2) had the greatest effect on the evaporation kinetics, while the effect of the MgO content was comparatively less. The regression model developed based on the experimental design could describe the evaporation of K from actual BF slags fairly well, provided that they were within the experimental matrix of the design of experiments.
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| 40. |
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| 41. |
- Andersson, Anton, et al.
(författare)
-
The Potential of Recycling the High-Zinc Fraction of Upgraded BF Sludge to the Desulfurization Plant and Basic Oxygen Furnace
- 2018
-
Ingår i: Metals. - : MDPI. - 2075-4701. ; 8:12
-
Tidskriftsartikel (refereegranskat)abstract
- In ore-based steelmaking, blast furnace (BF) dust is generally recycled to the BF via the sinter or cold-bonded briquettes and injection. In order to recycle the BF sludge to the BF, the sludge has to be upgraded, removing zinc. The literature reports cases of recycling the low-zinc fraction of upgraded BF sludge to the BF. However, research towards recycling of the high-zinc fraction of BF sludge within the ore-based steel plant is limited. In the present paper, the high-zinc fraction of tornado-treated BF sludge was incorporated in self-reducing cold-bonded briquettes and pellets. Each type of agglomerate was individually subjected to technical-scale smelting reduction experiments aiming to study the feasibility of recycling in-plant residues to the hot metal (HM) desulfurization (deS) plant. The endothermic reactions within the briquettes decreased the heating and reduction rate leaving the briquettes unreduced and unmelted. The pellets were completely reduced within eight minutes of contact with HM but still showed melt-in problems. Cold-bonded briquettes, without BF sludge, were charged in industrial-scale trials to study the recycling potential to the HM deS plant and basic oxygen furnace (BOF). The trials illustrated a potential for the complete recycling of the high-zinc fraction of BF sludge. However, further studies were identified to be required to verify these results.
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| 42. |
- Andersson, Anton, et al.
(författare)
-
The Quantitative Effect of Blast Furnace Slag Composition and Temperature on the Kinetics of Potassium Evaporation
- 2020
-
Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 51:6, s. 2711-2723
-
Tidskriftsartikel (refereegranskat)abstract
- Increased in-plant recycling and lower quality raw material in terms of alkali content drive the alkali load in the blast furnace (BF) to higher levels. Excessive load of alkalis, primarily potassium, has several negative effects on the BF operation, which necessitates means to control the removal of potassium from the BF. One method to improve the removal is by increasing the potassium retention in the slag, which is controlled by the evaporation kinetics of potassium. Although several authors have studied factors affecting the evaporation rate, none of these studies have quantitatively investigated the effect of these parameters and attempted to relate these effects to slags from the industry. In the present work, a full-factorial design of experiments with three factors (B2 basicity, MgO content, and temperature) was performed, studying the evaporation of potassium from synthetic BF slag. The results suggested that multiple linear regression is suitable to describe the evaporation kinetics of potassium within the boundaries of the design of experiments. However, extrapolating to industrial slags of different compositions and additional slag components is best performed utilizing the corrected optical basicity. The corrected optical basicity showed a linear relation to the evaporation kinetics of potassium, which was related to the correlation between diffusivity and corrected optical basicity.
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| 43. |
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| 44. |
- Andersson, Charlotte, et al.
(författare)
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The need for fundamental measurements for a sustainable extraction of metals
- 2011
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Ingår i: Mineral Processing and Extractive Metallurgy. - 0371-9553 .- 1743-2855. ; 120:2, s. 199-204
-
Tidskriftsartikel (refereegranskat)abstract
- The increased need for efficient material processing and efficient utilisation of more complex raw materials and the need for recycling or reusing byproduct and waste streams, are all increased challenges in material processing. To cope with these challenges, there is a need for new basic physical and thermodynamic data. The present paper gives four examples, as well as preliminary data, of areas where increased knowledge of fundamental parameters will increase the possibility for a sustainable extraction of metals. The examples include measurement of solubility of pure individual slag minerals, determination of distribution of leachable elements between different mineralogical phases in slag, influence of alumina on liquidus temperature of a copper slag and thermal diffusivity measurements in magnetite based iron ore pellets, all important in different ways to increase the sustainability of the respective materials involved
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| 45. |
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| 46. |
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| 47. |
- Bennich-Björkman, Bo
(författare)
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Bellman och förläggarna 1757-1771.
- 2005
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Ingår i: Bellmanstudier utgivna av Bellmanssällskapet. Samling 22. - : Proprius, Stockholm. ; , s. 35-59
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 48. |
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| 49. |
- Bennich-Björkman, Bo
(författare)
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Delblanc och Da Vinci-koden
- 2005
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Ingår i: Uppsala Nya Tidning. ; :27 november, s. B6-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 50. |
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