Recycling titanium from Ti-waste by a low-temperature extraction process

Abstract

In the commercial chloride process, titanium is extracted from Ti concentrates at high temperatures (800–1,500°C), and the high-purity rutile is the primary raw material. Chlorination at high temperatures results in high-energy consumption, rapid corrosion of equipment, pipelines and control system, and agglomeration of the solid bed by the liquid byproducts. The high-purity rutile is expensive and its natural deposit is being depleted. Therefore, a low-temperature Ti extraction process using Ti-waste as the primary raw material is highly desirable. Thermodynamic equilibrium simulation of the reaction system shows that the extraction of Ti from Ti waste is feasible at a temperature as low as 200°C. In this study, a simple technology was used to remove diffusion barriers, and a low-temperature chloride process was developed. The chlorination reaction operates at 300–350°C, and Ti-waste can be used to replace the expensive rutile. Up to 80% of the titanium can be recycled in 5 min at 350°C. The extraction of other components has a relatively low extent, so a selective extraction of Ti can be achieved. A fluidized-bed reactor was used for the chlorination process. The formation of an activated TiO2–C–Cl complex on the TiO2/C interface accounts for the gas-solid-solid reaction mechanism.