Analysis of Fe and Mn impurities in Chinese sponge titanium enterprise using an input-output model

The impurity content is an important index reflecting the quality of sponge titanium, especially Fe and Mn impurities. However, at present, only qualitative research has been conducted on the input of impurities, and no quantitative research has been conducted on the input and output of impurities. Therefore, based on the input-output model, this study analyzes the input and output of typical impurities in the magnesiothermic reduction-vacuum distillation process, product sorting process, and magnesium processing process, respectively. Quantitative characterization of the input and output of impurities in sponge titanium production. The results show that the Fe impurity is mainly input by the equipment, and the Mn impurity is mainly input from the raw materials. Determined the chemical reactions of impurities Fe and Mn during reduction, impurities of Fe and Mn exist in the product as the form of simple substance after the reaction.

Effect of Microstructure of Surface Layer in Steel Vessel Used for Sponge Titanium Manufacturing on Fe Elution

To make clear factors affecting Fe elution into molten Mg during sponge titanium production process and reasons why Fe elution from the steel vessel in the first use is high while it considerably reduces in the second use in the actual mill, immersion experiments into molten Mg at 950ºC were conducted using specially designed specimens simulating the first and the second uses of the vessel, and microstructure change of the steel during the use was investigated in detail. TiFe, TiFe2 and Ti-diffused steel layers formed on the surface of the steel specimen after the treatment similar to the first use of the vessel. The outermost portion of Ti-diffused steel contained 3mass% Ti, which should have transferred to the α phase at this temperature. Fe elution from TiFe and TiFe2 was almost zero, while Fe elution from Fe-3mass%Ti was 1/4 of that from the unused steel. By taking the information on the phases appeared on the surface of the actual vessel into account, Fe elution from the vessel at the second use was estimated as 1/16 of that at the first use, which is well consistent with the value in the actual production mill.