Experimental Study on Phosphorus Partitions Between Liquid Iron and Liquid Slags Based on DRI

Martinsson

Sichen

2020

Self‐fluxing hematite pellets are reduced by hydrogen to different degrees. The reduced pellets are melted in closed MgO crucibles at 1873 K to study the effect of reduction degree on the characteristics of slag formed. The results reveal that the phosphorus content in the metallic phase can be brought down to 130 ppm merely by the self‐fluxing slag, even though the slag weighs only about 8% of the metal. It shows a great potential in reducing the amount of slag formers in the steelmaking process. The slag compositions obtained by melting the reduced pellets are used to prepare small synthetic slag samples for identifying the phases after melting. The use of the small samples is to ensure efficient quenching. Microscopic examination reveals that all the self‐fluxing slags contain mainly three phases, namely, magnesiowüstite, spinel, and a liquid phase. Most of vanadium is found to be in the spinel and magnesiowüstite phases. The liquid phase only contains 1–2 wt% V2O3. Decreased FeO content of the slag increases the vanadium oxide contents in the spinel and magnesiowüstite phases. The fact that vanadium concentrates in the solid oxide phases provides essential information for sustainable extraction of vanadium from the steelmaking slag.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effect of Reduction Degree on Characteristics of Slag Formed by Melting Hydrogen‐Reduced DRI and Partitions of P and V between Slag and Metal

Martinsson

Sichen

2020

“…Unfortunately, it has often been assumed that the capacity (sulfide or phosphate) is independent of the oxygen potential, even when systems contain multivalent species. Measurements for systems that contain multivalent species have, therefore, been carried out over a wide oxygen potential range typically from 1 Â 10 À12 to 1 Â 10 À6 atm for phosphate capacity measurements [34][35][36][37][38][39][40][41][42][43][44][45][46] and 1 Â 10 À12 to 1 Â 10 À5 atm for sulfide capacity measurements. [1, On the other hand, the oxygen potentials prevailing in the reactors only partly coincide with these ranges.…”

Section: Sulfide Capacity and Phosphate Capacitymentioning

confidence: 99%

“…[62] This structure variation with oxygen potential would likely lead to the variation of thermophysical properties, e.g., viscosity, as well as the thermochemical properties of the slag. [63][64][65] As a matter of fact, great controversy has been noticed when comparing the literature data for C P or phosphorus partition in the CaO-SiO 2 -MgO-FeO x system at 1873 K. [34][35][36][37][38][39][40] To the best of authors knowledge, the variation of thermophysical and thermochemical properties with oxygen potential for steelmaking slags has not been studied systematically. A systematic study of the dependence of the properties of slags containing multivalence species, e.g., iron oxides, vanadium oxides, and titanium oxides on the oxygen potential would be greatly needed.…”

Section: Structure Of Silicate Melts With Transitional Speciesmentioning

confidence: 99%

The Laboratory Study of Metallurgical Slags and the Reality

Sichen

Huss

et al. 2021

Self Cite

The development of new materials and their production processes along with the environmental constraints demand new data of high quality, especially thermodynamic and physical property data. As slags play a crucial role in metallurgical processes and recycling, the need of better understanding of the reaction mechanisms between slag and metal is also increasingly felt. High precision data and better understanding of the reaction mechanism require efficient collaboration between the researchers in the laboratory and in the industries. Unfortunately, in some cases, the reported data are not obtained in well-controlled experimental conditions. Without the knowledge of the experimental conditions, the use of the data in industrial practice would possibly lead to unintended results. In other cases, the measurements themselves, even their principles, are questionable. This review article addresses how to make the laboratory investigation more relevant to the industrial reality. Some existing uncertainties in the laboratory studies are also discussed. To help a sensible discussion, some specially designed experiments are conducted to support the argument. The review is focused on slag properties (namely, sulfide capacity, phosphate capacity, apparent viscosity, and apparent interfacial tension) and studies of interfacial slag phenomena.

Some Aspects of the Melting and Dephosphorization Mechanism of Hydrogen‐DRI

Huss

Kojola

2023

Self Cite

To meet the future environmental challenges, hydrogen direct reduced iron (H‐DRI) is expected to constitute the principal material for virgin steel production. For an efficient value chain, knowledge of the melting mechanism and dephosphorization mechanism of H‐DRI is needed. The in situ melting behavior, the melting mechanism, and the dephosphorization mechanism during heating of H‐DRI are investigated experimentally at 1773 and 1873 K. It is found that the melting rate of H‐DRI varies with the reduction degree (91–99.5%), increasing with decreasing reduction degree. An autogenous slag forms during heating and flows through the pores of the H‐DRI, thus increasing its effective thermal conductivity. The fraction of filled pores varies with reduction degree explaining the difference in melting rate. At this stage, the dissolution of apatite is initiated and completed upon melting of the metal phase. A gradual reversion of phosphorus from the autogenous slag to the liquid metal is observed after complete melting. The rate of reversion is discussed based on the properties of the H‐DRI, for example, reduction degree and carbon addition.