Crystallization Control for Remediation of an FetO-Rich CaO–SiO2–Al2O3–MgO EAF Waste Slag

Jung, Sung Suk; Sohn, Il

doi:10.1021/es404277w

Cited by 73 publications

(43 citation statements)

References 40 publications

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“…In addition, maximizing metal recovery from the slags can increase productivity and decrease environmental treatment costs for the steel industry. From the works by Jung and Sohn, [73][74][75] instead of dumping the molten slag and allowing slow cooling, a controlled cooling pattern could concentrate the Fe cations into the spinel crystal structure (MgAlFeO 4 ) enriching local areas of the primary spinel crystals and separating the Fe from the amorphous phases of the slag, as illustrated in Fig. 13.…”

Section: Fe Separation and Enrichment In Eaf Slags Using Controlled Cmentioning

confidence: 99%

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Review of Innovative Energy Savings Technology for the Electric Arc Furnace

Lee

Sohn

2014

JOM

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A review of the energy innovations for the electric arc furnace (EAF) steelmaking route is discussed. Preheating of scrap using vertical and horizontal shafts that have been commercially successful in lowering the energy consumption to as much as 90 kWh/t reaching almost the operational limit to heating input scrap materials into the EAF is discussed. Bucket-type and twin-shell preheaters have also shown to be effective in lowering the overall power consumption by 60 kWh/t, but these have been less effective than the vertical shaft-type preheaters. Beyond the scrap preheating technologies, the utilization of waste heat of the slags from the laboratory scale to the pilot scale has shown possible implementation of a granulation and subsequent heat exchange with forced air for energy recovery from the hot slags. Novel techniques to increase metal recovery have shown that laboratory-scale testing of localized Fe concentration into the primary spinel crystals was possible allowing the separation of an Fe-rich crystal from an Fe-depleted amorphous phase. A possible future process for converting the thermal energy of the CO/ CO 2 off-gases from the EAF into chemical energy was introduced.

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Section: Fe Separation and Enrichment In Eaf Slags Using Controlled Cmentioning

confidence: 99%

“…SEM-EDS mapping of EAF slags containing FeO in the CaO-Al 2 O 3 -MgO-FeO slag system isothermally cooled to 1473 K. Note the localized concentration of Fe into the primary spinel crystals 73. …”

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confidence: 99%

Review of Innovative Energy Savings Technology for the Electric Arc Furnace

Lee

Sohn

2014

JOM

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“…The shift of wavenumber may be ascribed to the complex multiphase in the slag melts. Figure 6( [33] therefore, the crystallization temperature of the slag was increased, as shown in Figure 4(b). As Al 3+ is similar to Fe 3+ in the glass phase, [35] the ferric-and aluminium-based spinels are almost entirely homogeneous; [36] therefore, it cannot be distinguished from the DSC corves, i.e., a single peak represents the spinel mixture precipitation.…”

Section: B Raman Spectra Analysismentioning

confidence: 76%

“…This is consistent with previous studies. [21,33] However, [FeO 4 ]-tetrahedra and [FeO 6 ]-octahedra were also observed around 660 and 480 to 520 cm À1 in the V 2 O 5 -MoO 3 -Fe 2 O 3 slags, [34] respectively. The shift of wavenumber may be ascribed to the complex multiphase in the slag melts.…”

Section: B Raman Spectra Analysismentioning

confidence: 94%

Selective Crystallization Behavior of CaO-SiO2-Al2O3-MgO-FetO-P2O5 Steelmaking Slags Modified through P2O5 and Al2O3

Wang

Sun

Sridhar

et al. 2015

Metall Mater Trans B

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In this study, the selective crystallization behavior of synthetic Fe t O-rich steelmaking slags modified by P 2 O 5 and Al 2 O 3 additions was explored using non-isothermal differential scanning calorimetry, X-ray diffraction, and field emission scanning electron microscopy techniques. Continuous cooling transformation diagrams of Fe-enriched and P-enriched phases were constructed. It was found that P 2 O 5 addition can suppress the crystallization due to the increasing viscosity caused by increasing degree of polymerization; however, an increase of Al 2 O 3 content accelerated the precipitation of dystectic MgFeAlO 4 , copolymerized by [AlO 4 ]-tetrahedra and [FeO 4 ]-tetrahedra units. It was also noted that the content of phosphorus in P-enriched phase can reach a high value as 28.71 wt pct for the slags modified by 15.17 wt pct Al 2 O 3 . The nonisothermal crystallization kinetics derived from activation energy and the structure of the slags explained by Raman spectra were further analyzed, which was well in accordance with the above analysis.

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“…[22][23][24] Nevertheless, the phosphorus content in the residual slag was still too high for recycling to the steel-making process. Crystallization of magnetic phases at or near the liquidus temperatures of slags could facilitate further magnetic separation; [25][26] however, the amounts of the magnetic phases and distribution of phosphorous among constituent phases were not determined, imposing uncertainties on the efficiency of this approach. Apparently, the methods for dephosphorizing the BOF-slag require further refinement.…”

Section: Introductionmentioning

confidence: 99%

Reductive Heating Experiments on BOF-Slag: Simultaneous Phosphorus Re-Distribution and Volume Stabilization for Recycling

Yang

Lee

et al. 2016

steel research int.

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Basic-oxygen furnace (BOF) slag is the second abundant by-product from the steel-making process. It is not readily recycled for high phosphorus content and volume instability. To eliminate its phosphorus-hosting dicalcium silicate (C 2 S) and volumetrically unstable free-lime, reductive heating experiments on BOF-slag are carried out at 1300-1600 8C using quartz-sand or serpentine as a basicity modifier. In the products, C 2 S and free-lime are consumed through reacting with CaO and MgO, which are produced by Ca-ferrite and Mg-wustite reduction, respectively, to form merwinite and akermanite. The products are also characterized by silicatemetal segregation and the extent of that increases with increasing temperature and decreasing particle size of starting mixtures. Thermodynamic calculations show that phosphorus in C 2 S is mostly converted to Fe 2 P in the metal domain. Compared to the slag-serpentine experiments, the slag-quartz experiments resulted in higher extents of silicate-metal segregation with lower phosphorus contents of %0.1% in the silicate domain, which therefore is recyclable. To optimize silicate-metal segregation for recycling BOF-slag, it is suggested (i) bringing the BOF-slag composition within the low-temperature side of the C 2 S-merwinite-akermanite Alkemade triangle by adding quartz-sand; (ii) reductively heating to 1500-1600 8C; and (iii) cooling slowly then quenching to suppress C 2 S crystallization from melts.

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Crystallization Control for Remediation of an Fe_tO-Rich CaO–SiO₂–Al₂O₃–MgO EAF Waste Slag

Cited by 73 publications

References 40 publications

Review of Innovative Energy Savings Technology for the Electric Arc Furnace

Review of Innovative Energy Savings Technology for the Electric Arc Furnace

Selective Crystallization Behavior of CaO-SiO2-Al2O3-MgO-FetO-P2O5 Steelmaking Slags Modified through P2O5 and Al2O3

Reductive Heating Experiments on BOF-Slag: Simultaneous Phosphorus Re-Distribution and Volume Stabilization for Recycling

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