Removal of Mg and MgO By-Products through Magnesiothermic Reduction of Ti Powder in Self-Propagating High-Temperature Synthesis

Abstract

Commercial production of titanium involves chlorination using chlorine gas that can be converted to hydrochloric acid by atmospheric moisture and is hazardous to human health. In the titanium production process, self-propagating high-temperature synthesis is one of the process to directly reduce titanium dioxide. In this work, titanium powder was prepared by self-propagating high-temperature synthesis using titanium dioxide as the starting material and magnesium powder as a reducing agent. After the reaction, magnesium and magnesium oxide by-products were then removed by acid leaching under different leaching conditions, leaving behind pure Ti. During each leaching condition, the temperature of the leaching solution was carefully monitored. After leaching, the recovered titanium in the form of a powder was collected, washed with water and dried in a vacuum oven. Detailed compositional, structural, and morphological analyses were performed to determine the presence of residual reaction by-products. It was found that leaching in 0.4 M hydrochloric acid followed by second leaching in 7.5 M hydrochloric acid is the optimum leaching condition. Furthermore, it was also noticed that total volume of solution in 0.4 M hydrochloric acid leaching condition is advantageous to maintain uniform temperature during the process.

Effective Deoxidation Process of Titanium Scrap Using MgCl2 Molten Salt Electrolytic

“…Therefore, in the remaining MgO, if the impurity element and the formed reaction products such as MgCl 2 and MgO are removed through a subsequent leaching process, the dissolved oxygen will be removed as well. There are many related studies in the literature on the leaching process operation for the removal of MgO and MgCl 2 [35][36][37][38]. The most representative solution is an acidic solution such as HCl, H 2 SO 4 , and HNO 3 , as it does not react with the Ti metal while reacting with Mg-based compounds and other impurities according to the following equations:…”

Metals Powders: Synthesis and Processing

“…It consists of ten research papers focused on different materials and processes. The studied materials cover pure Ti [1,2] and Ta [3], and alloys with compositions Fe-Co-Cu [4]…”

“…Thus, Hwang at al. [3] studied the extraction of Ta powder, and Choi et al [2] the extraction of Ti. Ball milling is the technique used by Xiang et al [8] to obtain Mn-Bi powders with outstanding magnetic properties.…”

“…Several manuscripts [1][2][3][4]6,10] deal with crystalline materials, whereas other works [5,[7][8][9] use amorphous powders. According to the country of the corresponding author, three papers come from China [7][8][9], another three from Korea [2,3,6], two from Spain [5,10], one from USA-Spain [1], and one from Portugal [4]. In addition, authors from the United Kingdom, Germany, Mexico and Romania have contributed to the different papers.…”

“…Regarding powders synthesis, the production of Ti from TiO 2 by self-propagating high-temperature synthesis using Mg powder as reducing agent is studied in [2]. This process, avoiding the use of TiCl 4 , produces magnesium and magnesium oxide by-products that need being removed.…”