Production of Fe–Ti Alloys from Mixed Slag Containing Titanium and Fe₂O₃ via Direct Electrochemical Reduction in Molten Calcium Chloride

• Main Authors: Bo Wang, Chao-yi Chen, Jun-qi Li, Lin-zhu Wang, Yuan-pei Lan, Shi-yu Wang
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Metals
• Subjects: <b>Keywords: </b>waste slag containing titanium; molten salt electrolysis; ferro-titanium alloy; FeTi₄
• Online Access: https://www.mdpi.com/2075-4701/10/12/1611

High-purity intermetallic β-Ti (FeTi₄) and FeTi alloys were prepared via molten salt electrolysis from a titanium-containing waste slag and Fe₂O₃ mixture using molten CaCl₂ salt as the electrolyte. The mixed slag powders were pressed into a pellet that served as a cathode, while a graphite rod served as an anode. The electrochemical process was conducted at 900 °C with a cell voltage of 3.1 V under an inert atmosphere. The formation process of the alloys and the influence of the Ti:Fe atomic ratio on the product were investigated. With an increased proportion of Ti, the phase of the product changed from FeTi/Fe₂Ti to FeTi/FeTi₄, and different structures were observed. At a Ti:Fe ratio of 1.2:1 in the raw slag, an alloy with a sponge-like morphology and a small amount of FeTi₄ were obtained. During the initial stages of electrolysis, a large amount of intermediate product (CaTiO₃) was formed, accompanied by an abrupt decrease in current and increase in particle size. The current then increased and Fe₂Ti alloy was gradually formed. Finally, as the reaction process extended inside the pellet, the current remained stable and the product mainly contained FeTi and FeTi₄ phases. The observed stages, i.e., CaTiO₃(TiO₂) → Fe₂Ti(Ti) → FeTi(FeTi₄), were consistent with the thermodynamic analysis.