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Sar, S., Sundqvist Ökvist, L., Sparrman, T., Engström, F. & Samuelsson, C. (2019). Characterization of Double Leached Waelz Oxide for Identification of Fluoirde Mineral. Metals, 9(3), Article ID 361.
Open this publication in new window or tab >>Characterization of Double Leached Waelz Oxide for Identification of Fluoirde Mineral
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2019 (English)In: Metals, ISSN 2075-4701, Vol. 9, no 3, article id 361Article in journal (Refereed) Published
Abstract [en]

Double leached Waelz oxide (DLWO), with 76% zinc, is a secondary zinc containing raw materials obtained by the treatment of electric arc furnace dust. The content of fluoride in DLWO is still too high for direct leaching, as fluoride has a detrimental effect on electrowinning for zinc production. Knowledge of the characteristics of DLWO, and especially on how a fluoride mineral might exist, can contribute to further improvement of the selective leaching for the removal of fluoride. In this study, DLWO was characterized using analytical techniques, such as inductively coupled plasma-optical emission spectroscopy (ICP-OES), 19F liquid-state nuclear magnetic resonance (19F LS NMR), X-ray powder diffraction analysis (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and 19F solid-state nuclear magnetic resonance (19F SS NMR). This study showed that DLWO mainly consisted of zincite (ZnO), cerussite (PbCO3) and a spinel containing zinc, iron and manganese. The fluoride mineral identified was calcium fluoride (CaF2). In SEM analysis, fluorine was found in larger grains together with calcium and oxygen, which was possibly calcium carbonate.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
metal recycling; zinc secondary dust material; characterization of double leached Waelz oxide; halogens; fluoride identification
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-73646 (URN)10.3390/met9030361 (DOI)
Note

Validerad;2019;Nivå 2;2019-04-16 (oliekm)

Available from: 2019-04-15 Created: 2019-04-15 Last updated: 2019-04-24Bibliographically approved
Brämming, M., Engström, F., Samuelsson, C. & Björkman, B. (2019). Characterization of Slag‐Metal Emulsion and Its Impact on Foaming Behavior and Slopping in the LD Process. Steel Research International, 90(2), Article ID 1800269.
Open this publication in new window or tab >>Characterization of Slag‐Metal Emulsion and Its Impact on Foaming Behavior and Slopping in the LD Process
2019 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 90, no 2, article id 1800269Article in journal (Refereed) Published
Abstract [en]

In the Basic Oxygen Steelmaking (BOS) process, a heterogeneous emulsion‐solid mix will form, consisting of an emulsion of liquid slag and metal droplets, in which 2nd phase particles of undissolved fluxes and solid in‐blow precipitates are suspended. When the carbon in the metal droplets reacts with iron oxide, small bubbles of CO gas are formed. If the upward movement of these bubbles is obstructed by the physical properties of the emulsion‐solid mix, foaming will occur. Certain process conditions may lead to an excessive foam growth, in the worst case forcing foam out of the vessel. This undesired process event is known as “slopping”. Extensive studies during recent decades have shown that emulsion characteristics strongly connected to foaming are: viscosity, surface tension, and density. The extent of foaming is also dependent on bubble size; foaming increasing with smaller bubble size. However, investigations into the influence of the mineralogy and morphology of the emulsion‐solid mix on foaming in basic oxygen steelmaking are scarce. In this work, samples from trials in a 6‐tonne pilot plant BOS vessel are examined by XRD and with SEM for the determination of emulsion‐solid mix mineralogy and morphology at different stages of the oxygen blow. The study confirms the importance of tight process control in order to minimize the emulsion‐solid mix apparent viscosity and, hence, the foam height, but this without over‐oxidizing the liquid slag phase, which would result in increased gas generation within the slag‐metal emulsion.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
sic oxygen steelmaking (BOS), emulsion characterization, foaming, LD process, mineralogy, morphology, slopping
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-72759 (URN)10.1002/srin.201800269 (DOI)000458361600016 ()2-s2.0-85058014454 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-06 (johcin) 

Available from: 2019-02-01 Created: 2019-02-01 Last updated: 2019-03-08Bibliographically approved
Soltani Dehkharqani, A., Aidanpää, J.-O., Engström, F. & Cervantes, M. (2019). Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations. In: IOP Conference Series: Earth and Environmental Science. Paper presented at 29th IAHR Symposium on Hydraulic Machinery and Systems, 17-21 September 2018, Kyoto, Japan.. Institute of Physics (IOP), 240, Article ID 062007.
Open this publication in new window or tab >>Fluid added polar inertia and damping for the torsional vibration of a Kaplan turbine model runner considering multiple perturbations
2019 (English)In: IOP Conference Series: Earth and Environmental Science, Institute of Physics (IOP), 2019, Vol. 240, article id 062007Conference paper, Published paper (Refereed)
Abstract [en]

A water turbine runner is exposed to several perturbation sources with differentfrequencies, phases, and amplitudes both at the design and off-design operations. Rotor-statorinteraction, cavitation, rotating vortex rope, and blade trailing edge vortices are examples of suchperturbations which can disturb the runner. The rotor dynamic coefficients require beingdetermined to perform a reliable dynamic analysis. Fluid added inertia, damping, and stiffnesshave previously been investigated for individual perturbation frequencies for the torsionalvibration of a Kaplan turbine model runner. However, a number of perturbation sources mostlytake place simultaneously and alter the dynamics of the runner. Soltani et al. [1] have evaluatedthe torsional added parameters for a Kaplan turbine runner using numerical simulationsconsidering single perturbation frequency. In the present work, the fluid added parameters areassessed in the presence of multiple perturbation sources. A similar methodology is used. Asingle-degree-of-freedom (SDOF) model for the dynamic model and unsteady ReynoldsaveragedNavier–Stokes approach for the flow simulations are assumed. Perturbations withdifferent frequencies are applied to the rotational speed of the runner to determine the fluid addedparameters for the torsional vibration. A number of previously investigated frequencies arechosen and their combinations are investigated. In addition, two different phase shifts areconsidered between the applied perturbations to study the effect of phase. Two more test caseswith higher perturbation amplitude are also conducted to investigate its influence on the fluidadded inertia and damping. The results are compared with the previous study and the interactionof multiple perturbations on the added parameters is investigated.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2019
National Category
Mechanical Engineering Fluid Mechanics and Acoustics Other Mechanical Engineering
Research subject
Fluid Mechanics; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-72503 (URN)10.1088/1755-1315/240/6/062007 (DOI)
Conference
29th IAHR Symposium on Hydraulic Machinery and Systems, 17-21 September 2018, Kyoto, Japan.
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-04-11Bibliographically approved
Feng, Y., Kero, J., Yang, Q., Chen, Q., Engström, F., Samuelsson, C. & Qi, C. (2019). Mechanical Activation of Granulated Copper Slag and Its Influence on Hydration Heat and Compressive Strength of Blended Cement. Materials, 12(5), Article ID 772.
Open this publication in new window or tab >>Mechanical Activation of Granulated Copper Slag and Its Influence on Hydration Heat and Compressive Strength of Blended Cement
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2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 5, article id 772Article in journal (Refereed) Published
Abstract [en]

Mechanical activation of granulated copper slag (GCS) is carried out in the present study for the purposes of enhancing pozzolanic activity for the GCS. A vibration mill mills the GCS for 1, 2, and 3 h to produce samples with specific surface area of 0.67, 1.03 and 1.37 m²/g, respectively. The samples are used to replace 30% cement (PC) to get 3 PC-GCS binders. The hydration heat and compressive strength are measured for the binders and derivative thermogravimetric /thermogravimetric analysis (DTG/TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) are used to characterize the paste samples. It is shown that cumulative heat and compressive strength at different ages of hydration and curing, respectively, are higher for the binders blending the GCS milled for a longer time. The compressive strength after 90 d of curing for the binder with the longest milling time reaches 35.7 MPa, which is higher than the strength of other binders and close to the strength value of 39.3 MPa obtained by the PC pastes. The percentage of fixed lime by the binder pastes at 28 days is correlated with the degree of pozzolanic reaction and strength development. The percentage is higher for the binder blending the GCS with longer milling time and higher specific surface area. The pastes with binders blending the GCS of specific surface area of 0.67 and 1.37 m²/g fix lime of 15.20 and 21.15%, respectively. These results together with results from X-ray diffraction (XRD), FTIR, and SEM investigations demonstrate that the mechanical activation via vibratory milling is an effective method to enhance the pozzolanic activity and the extent for cement substitution by the GCS as a suitable supplementary cementitious material (SCM).

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2019
Keywords
blended cement paste; compressive strength; fineness; granulated copper slag; mechanical activation; pozzolanic activity
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-73164 (URN)10.3390/ma12050772 (DOI)000462543700088 ()30845730 (PubMedID)
Note

Validerad;2019;Nivå 2;2019-03-12 (inah)

Available from: 2019-03-12 Created: 2019-03-12 Last updated: 2019-04-23Bibliographically approved
Lennartsson, A., Engström, F., Björkman, B. & Samuelsson, C. (2019). Understanding the bottom buildup in an electric copper smelting furnace by thermodynamic calculations. Canadian metallurgical quarterly, 58(1), 89-95
Open this publication in new window or tab >>Understanding the bottom buildup in an electric copper smelting furnace by thermodynamic calculations
2019 (English)In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 58, no 1, p. 89-95Article in journal (Refereed) Published
Abstract [en]

Thermodynamic calculations were used to investigate the liquidus temperature of the slag and the possible influence on the buildup formation in an electric copper smelting furnace. The impact of parameters such as Fe/SiO2 ratio, partial pressure of oxygen and the content of the oxides ZnO, Al2O3 and Cr2O3 in the slag were investigated with respect to the liquidus temperature of the slag. Results show that the chromium content in the slag has the greatest impact on the liquidus temperature and on the formation of solid particles. The characterization of the buildup done earlier showed that spinel phases were among the dominating phases. This is supported by the thermodynamic calculations in the present paper, where the chromite solid solution was found to be the primary precipitation phase.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2019
Keywords
Copper smelting, FactSage, Buildup, Thermodynamic calculation, Spinel, Pyrometallurgy, Electric furnace
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-70765 (URN)10.1080/00084433.2018.1518804 (DOI)000452743200008 ()2-s2.0-85053228724 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-30 (inah)

Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2019-01-30Bibliographically approved
Xue, P., Yang, Q., Liu, G., Han, F. L., Liang, J., Engström, F. & Björkman, B. (2017). Air Quenching of Steel slag to Enhance its Hydraulic Activity for Recycling the Slag as Meterials in Cement and Concrete Applications. Paper presented at 2016 International Conference on Material Science and Engineering Technology, ICMSET 2016, Phuket, Thailand, 14-16 October 2016. Key Engineering Materials, 737, 488-493
Open this publication in new window or tab >>Air Quenching of Steel slag to Enhance its Hydraulic Activity for Recycling the Slag as Meterials in Cement and Concrete Applications
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2017 (English)In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 737, p. 488-493Article in journal (Refereed) Published
Abstract [en]

A steel slag has been treated by air granulation, in order to enhance cementitious properties of the slag. Two samples with sizes ranged 1.68-2.38mm and 212-297μm and coded as Slag A and Slag B, respectively, were chosen from the granulated slag for investigations. A sample of the original steel slag was also studied. XRD analyses indicated the formations of α-C2S, β-C2S, C2F, C2MS2, f-MgO and α-C2S, C2F, f-MgO in Slag A and Slag B, respectively. The phases in the two slag samples were quite different from the phases found in steel slag. The SEM results show a reduction of C2S sizes from 10-20μm for the steel slag to nano-scales by air quenching for Slag B. This treatment of air quenching has increased the cumulative heat of hydration to 105.35J/g measured for Slag B, almost two times greater than that of the steel slag. The study results demonstrate a high potential for utilizations of the steel slag in cement and concrete applications after the slag treatment by air quenching. The treatment may thus lead to an environmental friendly and cost-effective recycling for the steel slag. This can also contribute to the sustainable developments in the steel and cement/concrete industries.

Place, publisher, year, edition, pages
Trans Tech Publications, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-63511 (URN)10.4028/www.scientific.net/KEM.737.488 (DOI)2-s2.0-85027060966 (Scopus ID)
Conference
2016 International Conference on Material Science and Engineering Technology, ICMSET 2016, Phuket, Thailand, 14-16 October 2016
Note

Konferensartikel i tidskrift

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2017-11-28Bibliographically approved
Strandkvist, I., Sandström, Å. & Engström, F. (2017). Effect of FeO/MgO Ratio on Dissolution and Leaching of Magnesiowüstite. Steel Research International, 88(6), Article ID e201600322.
Open this publication in new window or tab >>Effect of FeO/MgO Ratio on Dissolution and Leaching of Magnesiowüstite
2017 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 6, article id e201600322Article in journal (Refereed) Published
Abstract [en]

If slag is to be used as construction material, the leaching of some elements, such as chromium must be limited. The leaching of slag depends on the leaching properties of the minerals in the slag. However, the leaching/dissolution properties of individual slag minerals are usually not studied. One common slag mineral that can contribute to the leaching of chromium is magnesiowüstite. The object of this study is to determine whether magnesiowüstite can be modified to avoid chromium leaching. Magnesiowüstite samples with different FeO/MgO ratios with and without chromium content are manufactured. The dissolution is evaluated at pH 7 and 10 using the magnesiowüstite samples without chromium, at size fraction 20–38 μm, by measuring the acid consumption required to maintain constant pH level. The magnesiowüstite samples with chromium content are leached at pH 10; the leachate is analyzed for chromium. The results are unanimous, with increasing FeO content the dissolution of magnesiowüstite and leaching of chromium decrease. At pH 10 the magnesiowüstite, with ≥60 wt% FeO show no sign of dissolution and no chromium leaching could be detected with ≥70 wt% FeO. The results prove that the FeO content can stabilize magnesiowüstite and, thereby, prevent chromium leaching

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-61445 (URN)10.1002/srin.201600322 (DOI)000404545600006 ()2-s2.0-85020044828 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-02 (andbra)

Available from: 2017-01-16 Created: 2017-01-16 Last updated: 2018-07-10Bibliographically approved
Jiang, L., Bao, Y., Yang, Q., Chen, Y., Liu, G., Han, F., . . . Deng, J. (2017). Formation of Spinel Phases in Oxidized BOF Slag under Different Cooling Conditions. Steel Research International, 88(11), Article ID 1700066.
Open this publication in new window or tab >>Formation of Spinel Phases in Oxidized BOF Slag under Different Cooling Conditions
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2017 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 11, article id 1700066Article in journal (Refereed) Published
Abstract [en]

To enhance utilization of wastes generated from steelmaking, a BOF slag sample from Ning Steel group in China is treated by oxidizing at 1500 °C for 30 min and then cooled by different methods. The treated samples are characterized, in combination with calculations using FactSage 6.4. XRD results show that iron oxides in BOF slag are converted largely by the oxidation to spinel phases, Fe3O4 and MgFe2O4, which also eliminates free CaO and MgO. EDS analyses show Fe element existing in di-calcium silicate and glass phase, which are Fe3+ ions formed by oxidation. An incorporation of Fe3+ ions into crystal structures has stabilized high temperature polymorph of C2S, β-C2S, and α’-C2S, in the treated slag samples. Fe3+ ions may also act as a network former to facilitate glass formation. This may make it possible for the glass and α’-C2S phase to complement each other, leading to a higher hydraulicity, while the BOF slag, after the spinel separation, is blended in cements. Some suggestions are proposed, based on the present and early studies, to enhance hydraulicity for the BOF slag, as well as grain sizes of spinel phases, which may result in economic and environmental benefits for steel and cement industries.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-64098 (URN)10.1002/srin.201700066 (DOI)000414464400011 ()
Note

Validerad;2017;Nivå 2;2017-11-06 (andbra)

Available from: 2017-06-16 Created: 2017-06-16 Last updated: 2018-05-04Bibliographically approved
Strandkvist, I., Engström, F. & Andersson, A. (2017). Influence of basicity on chromium leaching of low alloy EAF slag. In: : . Paper presented at 3rd ESTAD 2017 : European Steel Technology and Applications Days, Vienna, Austria, 26-29 June 2017.
Open this publication in new window or tab >>Influence of basicity on chromium leaching of low alloy EAF slag
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Due to excellent properties as a construction material slag is rising in popularity as a resource. However, some properties prevent usage, one of those is leaching of chromium. The leaching of slag is governed by the solubility of theminerals. By eliminating soluble minerals that contain chromium the chromiumleaching should decrease. In some low alloy EAF slag, brownmillerite, has beensuspected to leach chromium. By increasing the basicity of slag the formation of brownmillerite should be avoided. Low alloy EAF slag with basicity of 2.7 was altered by remelting the slag with SiO2 additions. The mineralogical composition was identified using SEM EDS and XRD. Slag samples were treated inan autoclave to simulate ageing. The autoclave treatment was successful as theremelted slag without modification leached with the same magnitude as the naturallyaged reference sample. At basicity 2.7, the investigated slag had the highest leaching of chromium, at average 2 mg/kg. The chromium leaching decreased to 0.2 mg/kg at basicity 2.4. The decrease of chromium leaching was connected to the decrease of brownmillerite. Lower basicity did not eliminate leaching ofchromium as merwinite, another mineral able to contain chromium, was formed instead of brownmillerite.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-64939 (URN)
Conference
3rd ESTAD 2017 : European Steel Technology and Applications Days, Vienna, Austria, 26-29 June 2017
Available from: 2017-08-03 Created: 2017-08-03 Last updated: 2017-11-28Bibliographically approved
Xue, P., He, D., Xu, A., Gu, Z., Yang, Q., Engström, F. & Björkman, B. (2017). Modification of industrial BOF slag: Formation of MgFe2O4 and recycling of iron. Journal of Alloys and Compounds, 712, 640-648
Open this publication in new window or tab >>Modification of industrial BOF slag: Formation of MgFe2O4 and recycling of iron
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2017 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 712, p. 640-648Article in journal (Refereed) Published
Abstract [en]

Efficient recycling of iron oxide from industrial BOF (basic oxygen furnace) slags has always been an issue in metallurgy. In this study, a new method was developed for the efficient recycling of iron oxide: It was transformed into magnesioferrite spinel (MgFe2O4) by mixing the industrial BOF slag with 6.00% SiO2 first, and then the modified slag got cooled down from 1400 °C to 1270 °C at a rate of 1 °C/min. Finally, the Fe resources were recycled by magnetic separation. Various experiments and analyses such as XRD, SEM–EDS analyses, Factsage thermodynamic simulation, magnetization characterization, dry magnetic separation, and chemical analysis were carried out. The results show that the obtained MgFe2O4 has a high melting point (1716.76 °C in theory) and ferromagnetism (specific magnetic susceptibility of (8.03–206.84) × 10−5 m3/kg). Therefore, it could be separated from the weakly magnetic industrial BOF slag (specific magnetic susceptibility of (0.024–0.136) × 10−5 m3/kg). Furthermore, this new method could be applied to different BOF slags. The yield of MgFe2O4 increased to above 80% when the content of Fe2O3 was in the range 25.81–46.90%. After the modification and magnetic separation, the total Fe content increased by 15.80%, from 21.20% in the industrial BOF slag to 37.00% in the magnetic slag. This is better than the direct magnetic separation of iron oxide without any treatment. The magnetic slag could be reused as either a sintering or slag splashing material. The nonmagnetic slag can be used to produce high value-added building materials. Hence, this new method can be used to recycle the iron oxide from industrial BOF slags, achieving the sustainable development of the iron and steel industry.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-63047 (URN)10.1016/j.jallcom.2017.04.142 (DOI)000401881000084 ()2-s2.0-85017648681 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-04 (andbra)

Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2018-09-13Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-9297-8521

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