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- Basu, Somnath, et al.
(author)
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Distribution of phosphorus and oxygen between liquid steel and basic oxygen steelmaking slag
- 2009
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In: Revue de métallurgie (Imprimé). - : EDP Sciences. - 0035-1563 .- 1156-3141. ; 106:1, s. 21-
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Journal article (peer-reviewed)abstract
- The efficiency of dephosphorisation is governed by the thermodynamic behaviour of phosphorus and oxygen in molten metal, and P2O5 and FeO in slag. The equilibrium distribution of phosphorus and oxygen, for a wide range of chemical compositions simulating the evolution of slag composition during a typical BOF blow, has been experimentally determined. A mathematical model for estimation of the activity coefficients, as a function of the chemical composition, was also attempted.
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| 4. |
- Basu, Somnath, et al.
(author)
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Phosphorus partition between liquid steel and CaO-SiO2-FeOx-P2O5-MgO slag containing 15-25 %FeO
- 2007
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In: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 38:4, s. 623-630
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Journal article (peer-reviewed)abstract
- CaO-SiO2-FeO2-P2O5-MgO bearing slags are typically used in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influence of factors such as FeO content and basicity on the phosphorus partition ratio was investigated at two different temperatures. The partition ratio initially increased with basicity but remained constant beyond a basicity of 2.5 to 2.6. An increase in the FeO content up to 18 to 20 mass pct was beneficial for the phosphorus partition at a basicity level of 2 to 3, but a higher concentration of FeO resulted in a decrease in the phosphorus partition ratio; the FeO concentration corresponding to this transition varied with basicity and temperature. At even lower basicities, however, the equilibrium phosphorus partition showed either no change, or a marginally decreasing trend, with an increase in the FeO content.
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| 5. |
- Basu, Somnath, et al.
(author)
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Phosphorus partition between liquid steel and CaO-SiO2-P2O5-MgO slag containing low FeO
- 2007
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In: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 38:3, s. 357-366
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Journal article (peer-reviewed)abstract
- CaO-SiO2-FeOx-P2O5-MgO bearing slags are typical in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influences of FeO concentration and basicity on the equilibrium phosphorus partition ratios were experimentally determined at temperatures of 1873 and 1923 K, for conditions of MgO saturation. The partition ratio initially increased with basicity but attained a constant value beyond basicity of 2.5. An increase in FeO concentration up to approximately 13 to 14 mass pet was beneficial for phosphorus partition.
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| 6. |
- Basu, Somnath, 1975-
(author)
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Studies on dephosphorisation during steelmaking
- 2007
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Doctoral thesis (other academic/artistic)abstract
- This work is aimed at understanding the thermodynamic principles influencing the phosphorus partition between slag and steel during steelmaking, particularly during refining of high-phosphorus hot metal using the basic oxygen steelmaking (BOS) process. Mapping of the slag path has been carried out using a mass balance model based on input conditions and off-gas analysis, which has been validated by intermediate measurements of slag and metal composition in an industrial basic oxygen furnace (BOF). The slag composition is found to vary over a wide range of basicity (%CaO/%SiO2) and iron oxide content. The partition of phosphorus increases with progress of refining but reduces during the intermediate period, corresponding to a decrease in iron oxide concentration and formation of “dry slag”. The phosphorus partition ratio increases again towards the end of the process. The equilibrium partition ratios for such conditions have been theoretically estimated using slag “model(s)”, based on the estimated slag compositions. It is seen that the partition ratio of phosphorus remains within 45% – 60% of the equilibrium value, showing a gradual decrease with progress of the refining process. Equilibrium phosphorus partition ratios for slags containing low concentrations of MnO and Al2O3 have been experimentally determined, over the ranges of basicity and iron oxide concentration approximately corresponding to that observed in the typical BOS process. It is seen that the equilibrium phosphorus partition ratio is practically independent of basicity greater than 2.5 – 2.6, over the entire range of temperature and FeOx concentration studied. Variation of the activity of P2O5 with basicity and FeOx concentration has been investigated to explain the trends observed in the variation of phosphorus partition ratio. It is seen that the activity coefficient of P2O5 is lowest, and hence most conducive for removal of phosphorus from steel, over certain finite ranges of basicity and iron oxide concentration. It follows that the efficiency of dephosphorisation is likely to be maximum if the basic oxygen steelmaking process is operated within these ranges. Simultaneous with this work, mathematical correlations have been developed for estimation of P2O5 activity coefficient and phosphorus partition ratio as functions of slag composition. The correlations are compared with those proposed by earlier workers and are found to result in better predictions over certain composition ranges.
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| 7. |
- Mahanta, C., et al.
(author)
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Preliminary assessment of arsenic distribution in brahmaputra river basin of India based on examination of 56,180 public groundwater wells
- 2015
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In: Safe and Sustainable Use of Arsenic-Contaminated Aquifers in the Gangetic Plain: A Multidisciplinary Approach. - Cham : Springer. - 9783319161242 ; , s. 57-64
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Book chapter (other academic/artistic)abstract
- Arsenic (As) rich groundwater in alluvial aquifers is a worldwide problem (Nriagu JO, Bhattacharya P, Mukherjee AB, Bundschuh J, Zevenhoven R, Loeppert RH, Arsenic in soil and groundwater: an introduction. In: Bhattacharya P, Mukherjee AB, Bundschuh J, Zevenhoven R, Loeppert RH (eds) Arsenic in soil and groundwater environment: biogeochemical interactions, health effects and remediation. Trace metals and other contaminants in the environment, vol 9 (Ser Ed Nriagu JO). Elsevier, Amsterdam, 2007). Elevated arsenic concentrations have long been detected in Southeast Asia (e.g. Thailand, Myanmar, Vietnam, Cambodia and Lao), India, Bangladesh, China, Mongolia, Nepal and Pakistan (Smedley PL, Kinniburgh DG, Appl Geochem 17:517-568, 2002). Recent reports of discovery of arsenic (As) enrichment in groundwater of the Brahmaputra river basin (Bhattacharya P, Mukherjee A, Mukherjee AB, Arsenic contaminated groundwater of India. In: Nriagu J (ed) Encyclopedia of environmental health. Elsevier B.V, Amsterdam, 2011) has exposed a significantly large population inhabiting in the river valley to serious health threats, although the actual distribution and extent of the As affected groundwater in the aquifers are yet to be established. Because of its vicinity to the highly As rich groundwater regions of Bengal basin (Bangladesh and West Bengal state of India), the extent of the polluted areas within the Brahmaputra basin may be much wider than what is initially understood. Groundwater arsenic contamination in the Brahmaputra basin aquifers in Assam, a state in the northeastern part of India, has started gaining attention relatively recently. Singh (Arsenic contamination in groundwater of North Eastern India. In: Proceedings of 11th national symposium on hydrology with focal theme on water quality. National Institute of Hydrology, Roorkee, 2004) reported maximum groundwater arsenic concentrations in Jorhat district (Fig. 4.1), located in the southern bank of the Brahmaputra river in Assam (maximum groundwater As concentration ranges between 194 and 657 μg/L), with relatively lower concentrations in the northern bank like Lakhimpur district (50-550 μg/L). Based on studies conducted in Darrang and Bongaigaon districts located in the northern bank (Fig. 4.1) of the Brahmaputra river in Assam, Enmark and Nordborg (Arsenic in the groundwater of the Brahmaputra floodplains, Assam, India-Source, distribution and release, mechanisms. Retrieved from the url: www2.lwr.kth.se/Publikationer/PDF_Files/MFS_2007_131.pdf, 2007) reported the concentration of arsenic in the two districts between 5 and 606 μg/L. In a study conducted in 2010 (Mahanta C, Pathak N, Bhattacharya P, Enmark G, Nordborg D, Source, distribution and release mechanisms of arsenic in the groundwater of Assam floodplains of Northeast India. In: Proceedings of the World Environmental and Water Resources Congress sponsored by Environmental and Water Resources Institute (EWRI) of the American Society of Civil Engineers, 2008), concentrations beyond 50 μg/L have been confirmed in 72 blocks out of 214 blocks in 22 districts of Assam. A study by Chetia M, Chatterjee S, Banerjee S, Nath MJ, Singh D, Srivastava RB, Sarma HP (Environ Monit Assess 173:1393-1398, 2011) in the Golaghat district reported As concentration ranging between 1 and 128 μg/L in six blocks of the district. These studies so far have remained spatially limited and a comprehensive picture is yet to emerge. To comprehensively evaluate the extent of As contamination in the region, a blanket rapid assessment study was undertaken in large parts of the Brahmaputra basin in Assam. This paper reports the preliminary assessment of arsenic distribution in the Brahmaputra basin in Assam based upon results from 56,180 public groundwater wells, tested during the rapid assessment programme.
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| 8. |
- Rozario, Albin, et al.
(author)
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Draining of gas bubbles at interface between two liquids-some observations
- 2015
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In: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking. - : The Chinese Society for Metals. - 9780000000002 ; , s. 328-331
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Conference paper (peer-reviewed)abstract
- In steelmaking operations, slag foaming plays an important role in energy efficiency, heat transfer and process kinetics. A cold model simulation of slag foaming phenomenon in steel making operation was conducted to understand the effect of viscosity, density and interfacial energy between steel and slag on foaming. The experimental study was conducted at room temperature using water and oils of different viscosities which represent steel and slag respectively. Experiments on individual bubble motion across water-oil interface showed that the residence time of bubble at the interface increased with increase in interfacial tension. It also showed the foam index was influenced by the carryover of water across the interface by gas bubbles which in turn depend on the velocity of gas, density and viscosity of the mediums. Foaming experiments with oil phase only showed that the foaming height increased with increase in viscosity and decreased with further increase in viscosity by varying the gas velocity. Foam index in the oil phase experiments decreased with increase in gas velocity. But in water-oil system, the trend was entirely different from only oil phase experiment showing that the foam height and foam index not only depends on viscosity, density difference between the phases but also on the amount liquid transfer that takes place across the interface which affects the residence time of the bubbles
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| 9. |
- Singh, A. K., et al.
(author)
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Absence of paired crossing in the positive parity bands of Cs 124
- 2018
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In: Physical Review C. - 2469-9985. ; 97:2
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Journal article (peer-reviewed)abstract
- High-spin states in Cs124 were populated in the Ni64(Ni64,p3n) reaction and the Gammasphere detector array was used to measure γ-ray coincidences. Both positive- and negative-parity bands, including bands with chiral configurations, have been extended to higher spin, where a shape change has been observed. The configurations of the bands before and after the alignment are discussed within the framework of the cranked Nilsson-Strutinsky model. The calculations suggest that the nucleus undergoes a shape transition from triaxial to prolate around spin I≃22 of the positive-parity states. The alignment gain of 8â.,, observed in the positive-parity bands, is due to partial alignment of several valence nucleons. This indicates the absence of band crossing due to paired nucleons in the bands.
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