Thermodynamic Analysis of Titanium Removal from Molten iron Smelted with Large Amounts of Sodium Additives

TL;DR

This study uses thermodynamic calculations to analyze how temperature, oxygen, and sodium additives influence titanium removal from molten iron in a sodium carbonate-assisted process.

Contribution

It provides a thermodynamic perspective on titanium removal, highlighting optimal conditions and effects of sodium additives, which are rarely studied in this context.

Findings

Lower temperature favors titanium removal.

High oxygen content enhances titanium and phosphorus removal.

Excessive sodium inhibits titanium removal.

Abstract

High purity iron is obtained from vanadium-titanium magnetite (VTM) by one-step coal-based direct reduction-smelting process with coal as reductant and sodium carbonate (Na2CO3) as additives. Industrial experiments show that the process of treating molten iron with a large amount of Na2CO3 is effective in removing titanium from molten iron. However, the studies are rarely conducted in thermodynamic relationship between titanium and other components of molten iron, under the condition of a large amount of Na2CO3 additives. In this study, through the thermodynamic database software Factsage8.0, the effects of melting temperature, sodium content and oxygen content on the removal of titanium from molten iron are studied. The results of thermodynamic calculation show that the removal of titanium from molten iron needs to be under the condition of oxidation, and the temperature should be below the critical temperature of titanium removal (the highest temperature at which titanium can be removed). Relatively low temperature and high oxygen content contribute to the removal of titanium from molten iron. The high oxygen content is conducive to the simultaneous removal of titanium and phosphorus from molten iron. In addition, from a thermodynamic point of view, excessive sodium addition inhibits the removal of titanium from molten iron.