Separation of Ti from Bi-Ti alloy by Solid-Liquid Separation at High Temperature and Vacuum Distillation

Abstract

9 Ti 8 (Ti 濃度 : 47 mol%) の二相に分離する。 Bi 9 Ti 8 は密度差から液体 Bi の表面に浮上するため 17) ，これを回 収して合金中の Ti を濃縮する。その後，蒸留 (Distillation) 工程で の真空蒸留により Bi と Ti を分離する。なお，還元工程の副生成 物である塩化マグネシウム (MgCl 2 ) は，Kroll 法で行われている従 来の溶融塩電解法 (Mg 電解と呼ばれる ) によって Mg と塩素 (Cl 2 ) 高温での固液分離および真空蒸留を利用した Bi-Ti 合金からの Ti の分離 * Separation of Ti from Bi-Ti alloy by Solid-Liquid Separation at High Temperature and Vacuum DistillationA new Ti smelting process via. Bi-Ti alloy is proposed. This process comprises reduction of TiCl 4 to Bi-10 mol%Ti alloy by Bi-Mg alloy, precipitation of Ti-rich compound from the alloy, and vacuum distillation. In this study, we investigated the precipitation and distillation processes.In the precipitation process, the Bi-10 mol%Ti liquid alloy is cooled from 900 ℃ to 500 ℃ to precipitate Bi 9 Ti 8 in the liquid alloy. The Bi 9 Ti 8 is recovered by a two-step separation method: recovery of mixture of Bi 9 Ti 8 and Bi and further removal of Bi by centrifugal filtration. We demonstrated the recovery of mixture. As the results, Ti concentration in the mixture was 31 mol%, and the Ti yield was about 45 %. Because the remained liquid alloy after the recovery contains a large amount of Bi 9 Ti 8 , it is required to reuse the remained alloy in the precipitation process. Assuming the reuse of remained alloy, the material flow of the process was designed based on the experimental results. The centrifugal filtration of the mixture of Bi 9 Ti 8 and Bi was also carried out at 500 ℃ . By the centrifugal filtration at 50 G, alloys with a size of 1.5 mm were obtained, and the Ti concentration in the alloys was increased from 31 mol% to 40 mol%.Vacuum distillation of alloy powder and ingot was demonstrated. The distillation rate was enhanced when using the powder than when using alloy ingot as a starting material.