Thermodynamics of Na2CO3-CaCO3-CaO slags for use in hot metal refining

Taskinen, Pekka; Janke, Dieter

doi:10.1002/srin.198305221

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…According to the thermodynamic calculations of Taskinen and Janke, [49] it is evident that in the presence of hot metal saturated with carbon, the stable form of Na 2 CO 3 is Na in a gaseous form. [49] However, as suggested by Kim et al, [50] in the presence of SiO 2 , Na 2 CO 3 is thermodynamically favored to decompose into Na 2 SiO 3 and only a small fraction of initial Na 2 CO 3 is decomposed into Na-gas if no carbon is available for the reaction, which is consistent with the results of Pak et al [32] In addition to this, as the rate of evaporation is controlled by either the rate of mass transfer or chemical reaction, the effect Na 2 O-loss on the sulfide capacity is rather small, but assumedly not negligible. [2,3,51,52] The evaporation rate of Na 2 O from the slag in the presence of carbon was studied by Li et al [51] in temperatures between 1300°C (1573.15 K) and 1500°C (1773.15 K).…”

Section: B Experimental Designmentioning

confidence: 99%

Identification of Rate, Extent, and Mechanisms of Hot Metal Resulfurization with CaO-SiO2-Na2O Slag Systems

Vuolio

Visuri

Paananen

et al. 2019

Metall Mater Trans B

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The resulfurization of hot metal has not been comprehensively studied in literature. This study presents an experimental and mathematical modeling study of resulfurization in thermodynamic and kinetic point of view. The rate, extent, and mechanisms of resulfurization were evaluated by analyzing concurrently the physical properties and sulfur-extracting ability of the slag. Experiments were conducted in a chamber furnace in an argon atmosphere, and the hot metal was sampled with pre-defined basis. The experiments were continued until the metal-slag system reached an apparent thermodynamic equilibrium. To obtain a quantitative measure on the effect of system properties on the rate and extent of resulfurization, the results of this study were combined with previous studies handling the sulfide capacities of Na 2 O-SiO 2 and CaO-SiO 2-Na 2 O slag systems. The sulfide capacities of the slag and corresponding metal-slag sulfur partition ratios were mathematically modeled with data-driven techniques such as multiple linear and non-linear regression and artificial neural networks. Finally, with the help of these, to study the kinetics of resulfurization, a simple mechanistic reaction model was derived. The results suggest that resulfurization of hot metal follows 1st-order kinetics and that the rate and extent can be regulated through the control of the associated thermodynamic driving force and by modifying the physical properties of the slag. The rate-limiting factor was found to be determined by the morphology of the slag phase.

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