Technology progress of the Kroll process for titanium sponge production

Titanium sponge constitutes a vital raw material in the production of titanium and its alloys. This review systematically elucidates the technology progress associated with the Kroll process. Currently, the batch size of the reactor for world-class titanium sponge companies is 10–13 tons. Compared with smaller batch reactors, production efficiency, energy consumption levels, and product quality have all seen significant improvements. For reactors larger than 10 tons, the main issues are how to further enhance the reduction and vacuum distillation processes while simultaneously maintaining good control over product quality. Approaches such as forced air cooling of reactor walls and the implementation of multi-tube TiCl4 feeding systems contribute to increasing the feeding rate of titanium tetrachloride. The development of vapour vent channels within the reaction mass improves the kinetic conditions. Critical factors for controlling impurity levels include the use of high-purity TiCl4, magnesium, and argon gas; upgrading the reactor material; precise control of process parameters; and accurate determination of the distillation endpoint. In the future, the advancement of titanium sponge production technology will focus on the application of advanced control systems, optimisation of reactor equipment structure and performance, improving production efficiency and product quality.