Hydrochloric acid (HCl) is a vital reagent widely utilised across the chemical industry. Notably, it plays a crucial role in the extraction of critical minerals that are strategically essential to Australia’s clean energy transition, advanced manufacturing capabilities, and national security. However, from an acid recovery perspective, the chloride liquor remaining after mineral extraction is typically either neutralised and stockpiled in wastewater ponds, or subjected to electrowinning to produce chlorine gas, which is then burned in hydrogen to regenerate HCl. This conventional pathway is energy-intensive, capital-heavy, and environmentally detrimental.
Over the past decade, my research group has focused on developing an alternative approach, namely pyro-hydrolysis for a direct conversion of metal chloride leachate into its respective metal oxides while simultaneously regenerating HCl acid for upstream reuse. Operating under significantly milder conditions than electrowinning, this technology also eliminates wastewater discharge. Intriguingly, its underpinning thermodynamic mechanisms remain far from fully understood. In this talk, I will elaborate on the fundamental knowledge we have uncovered over the years and present a practical case study on recovering magnesium from fly ash. Finally, I will discuss the future applications of this technology and demonstrate how the resulting products and by-products can be uniquely utilised in green chemistry and hydrogen production.
References (typical publications from our group in this area):
1. Cheng Liu, Song Zhou, Yang Liu, Dunxi Yu, Lian Zhang, Chem Eng J 2024, 480: 147929.
2. Cheng Liu, Song Zhou, Dunxi Yu, Barbara Etschmann, Lian Zhang, J Cleaner Production 2023, 419: 138195.
3. Cheng Liu, Jinxing Gu, Song Zhou, Binbin Qian, Barbara Etschmann, Jefferson Zhe Liu, Dunxi Yu, Lian Zhang, J Hazard Mater 2022, 439: 129620.
4. Song Zhou, Xue Yan, Cheng Liu, Binbin Qian, Jefferson Zhe Liu, Lian Zhang, ChemSusChem 2020, 13(24): 6660-6667.
5. Song Zhou, Binbin Qian, Tahereh Hosseini, Anthony De Girolamo, Lian Zhang, ACS Sustain Chem & Eng 2019, 7(3): 3349-3355.
6. Alfred Bekoe Appiagyei, Jinxing Gu, Alan L Chaffee, Qinfen Gu, Lian Zhang, Appl Cat B: Enviro and Energy 2025, 382: 125999.
7. Alfred Bekoe Appiagyei, Sasha Yang, Jinxing Gu, Alan Chaffee, Jefferson Zhe Liu, Qinfen Gu, Lian Zhang, Appl Cat B: Enviro and Energy 2025, 507: 160684.
8. Sasha Yang, Jinxing Gu, Binbin Qian, Jim Mensah, Adam F Lee, Karen Wilson, Barbara Etschmann, Xiya Fang, Jisheng Ma, Qinfen Gu, Lian Zhang, Chem Eng J 2024, 502: 157797.
9. Sasha Yang, Binbin Qian, Yuan Wang, Kenji Taira, Qiaoqiao Zhou, Karen Wilson, Adam F Lee, Lian Zhang, Appl Cat B: Enviro 2023, 322: 122106.
10. Binbin Qian, Sasha Yang, Jianghao Zhang, Song Zhou, Barbara Etschmann, Cheng Liu, Baiqian Dai, John Cashion, Yong Wang, Huanting Wang, Lian Zhang, Fuel Proc Technol 2022, 232: 107265.
11. Binbin Qian, Jianghao Zhang, Song Zhou, Jun Lu, Yue Liu, Baiqian Dai, Cheng Liu, Yong Wang, Huanting Wang, Lian Zhang, Appl Cat A: General 2021, 618: 118132.
12. Binbin Qian, Cheng Liu, Jun Lu, Meipeng Jian, Xiaoyi Hu, Song Zhou, Tara Hosseini, Barbara Etschmann, Xiwang Zhang, Huanting Wang, Lian Zhang, J Hazard Mater 2020, 395: 122696.