Titanium has a major market share of the $45B orthopedic implant market.
In the industry standard Kroll process for Ti primary metal production, concentrated Ti ore (an oxide) is first chlorinated to produce TiCl4. TiCl4 is then reduced to Ti metal with Mg. This technology is both capital- and energy-intensive.
Our team has developed a novel thermochemical process, namely hydrogen assisted metallothermic reduction (HAMR), to extract Ti metal from ore that substantially reduces the cost, energy consumption, and emissions of Ti metal production.
Based on the thermodynamic properties of Mg and Ti and their oxides, Mg is capable of reducing TiO2 to produce Ti metal. However, the equilibrium oxygen content in the Ti metal from Mg reduced TiO2 is typically higher than 1%, depending on the temperature used, which is unacceptable for industrial applications. This is because Ti-O solid solutions can be more stable than MgO.
In order to further reduce the oxygen content in Ti, we discovered that Ti-O can be destabilized using hydrogen, making it possible to tune the reduction of TiO2 with Mg from thermodynamically impossible to thermodynamically favored. This allows TiO2 to be reduced and deoxygenated directly by Mg to form TiH2, with low oxygen levels that can meet the needs of the industry. TiH2 can be further processed to Ti metal through industry standard approaches.
We can now produce Ti powder at a pilot scale. The HAMR Ti powder consistently meets the purity requirements defined by the industry standard and our team has developed a reliable recipe for pilot scale production of HAMR Ti powder.
A detailed energy-economic analysis and a full process simulation were performed to estimate the energy consumption, emissions, and cost at mass production. The result indicated that HAMR process is >50% less energy intensive and generates >30% less emissions than the Kroll process. The bulk of the energy and emissions savings comes through eliminating the need to chlorinate TiO2 to make TiCl4, and vacuum distillation after the reduction of TiCl4.
This is a promising technology that has the potential to drastically alter the Ti market and increase the range of applications for high performance, lightweight Ti parts.
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- Z. Zak Fang et al., Molten salt de-oxygenation of metal powders, US Patent App. 15/314,464
- Ying Zhang et al., Methods of deoxygenating metals having oxygen dissolved therein in a solid solution, US Patent 9,669,464
- Ying Zhang et al., Hydrogen assisted magnesiothermic reduction of TiO2, Chemical Engineering Journal 2017, 308, 299-310.
- Ying Zhang et al., A novel chemical pathway for energy efficient production of Ti metal from upgraded titanium slag, Chemical Engineering Journal 2016, 286, 517-527
- Ying Zhang et al., Thermodynamic destabilization of Ti-O solid solution by H2 and de-oxygenation of Ti using Mg, Journal of the American Chemical Society, 2016, 138, 6916-6919.
- Yang Xia et al. The effect of molten salt on oxygen removal from titanium and its alloys using calcium, Journal of Materials Science 2017, 52 (7), 4120-4128
- Yang Xia et al. Hydrogen Assisted Magnesiothermic Reduction (HAMR) of Commercial TiO2 to Produce Titanium Powder with Controlled Morphology and Particle Size, Materials transactions 2017, 58 (3), 355-360
- Yang Xia et al. Hydrogen enhanced thermodynamic properties and kinetics of calciothermic deoxygenation of titanium-oxygen solid solutions 2018, 43, 11939-11951
Approximately 14% of Boeing 787 is made of titanium.