Continuous Reduction Process of Titanium Chloride by Magnesium

研究了熔融盐连续还原法制备金属钛的工艺。作为传统工艺原料的氯化钛和镁，由于密度的差异，被分离到两个熔融层中。氯化钛气体被吹入下部熔盐，并被上部镁还原。沉淀在盐中的钛堆积在容器底部，然后从熔盐中提取出来。盐组成选用KCI、NaCl和LiCl，用于熔盐和还原剂的分离。致密的氧化镁适合作为坩埚材料。通过Kroll法得到的粉末比钛颗粒细1/10左右。还原的主要机理是熔盐中溶解的镁的还原，镁层的还原是添加剂的还原。在此基础上，提出了不与金属镁直接接触的氯化钛吹制新工艺。收率达80%以上。另一方面，得到的颗粒很小，而且分离得很好，从盐中分离出来变得很困难。第一个解决方案是适应冷凝过程，如液体旋风。过量还原剂附着在钛颗粒上，增强了颗粒的光泽。第二个解决方案是采取两步缩减。在第一步中，通过溶解一部分形成的钛粉，在熔盐中形成较低的氯化钛。第二步，这些高浓度的氯化物被镁还原。该方案易于连续操作，且较粗的颗粒易于回收。用同样的方法还原铌和钽的氯化物，得到它们的纯金属粉末。它们的细粒度适合于紧凑的大容量冷凝器。

A process to produce titanium metal in the molten salt was developed for continuous reduction. Titanium chloride and magnesium, which are used as raw materials for the conventional process, are separated into the two molten layers because of density difference. Titanium chloride gas is blown into the lower molten salt, and reduced by the upper magnesium. Titanium settled in the salt piles up on the vessel bottom, and it is extracted from the molten salt.The salt composition was chosen from KCI, NaCl and LiCl, to separate the molten salt and the reductant. The dense MgO was suitable for the crucible material. The obtained powder was about 1/10 finer than the titanium particle by the Kroll method. The main mechanism of reduction was the reduction by magnesium dissolved in the molten salt, and the reduction in the magnesium layer was additive. Considering this mechanism clarified here, a new technique that titanium chloride is blown without any direct contact with metallic magnesium was proposed. The yield was over 80%.On the other hand, the obtained particles were so small and well isolated that the separation from the salt became difficult. First solution was to adapt the condensification process such as liquid cyclone. The excess reductant adhered to titanium particles and enhanced the corsening. The second solution was to take a two-stepwise reduction. In the first step, the lower titanium chlorides are formed in the molten salt by resolving a part of formed titanium powder. In the second step, these highly concentrated chlorides are reduced by magnesium. This proposal are easily operated continuously, and the coarser particles were recovered easily.Similarly niobium and tantalum chlorides were reduced and their pure metallic powders were obtained. Their fine grain size was suitable for compact large capacity condensers.