Title: Hydrogen-Based Reduction of Zinc Cake: Comprehensive Thermodynamic Analysis, Kinetics, and Industrial Implementation
Authors: Kholikulov D.B., Mutalibkhonov S.S., Khudoymuratov Sh.J.
Volume: 9
Issue: 11
Pages: 199-216
Publication Date: 2025/11/28
Abstract:
- Zinc cake processing represents a critical metallurgical challenge in sustainable recycling and primary zinc extraction industries. This comprehensive research article synthesizes 50+ peer-reviewed publications from Scopus and Web of Science databases (2015-2025) to examine hydrogen-based reduction as an environmentally superior alternative to conventional carbothermal processing using coal and coke. Thermodynamic analysis demonstrates that zinc oxide reduction with hydrogen becomes thermodynamically favorable at 720°C, compared to 800°C for carbon monoxide reduction, offering significant energy efficiency advantages. Kinetic studies reveal temperature-dependent mechanisms: diffusion-controlled reduction (apparent activation energy 84.86 kJ/mol) dominates at 500-700°C, transitioning to reaction-front-limited processes (51.82 kJ/mol) above 700°C. Hydrogen reduction exhibits 2.5× faster kinetics for iron oxides and achieves 95% conversion in 25-30 minutes compared to 50-60 minutes for carbothermal reduction. Environmental analysis confirms that green hydrogen-based processing reduces CO? emissions by 85-95% compared to conventional methods (0.10 vs. 2.4 ton CO?/ton Zn recovered). Industrial implementation pathways include rotary hearth furnaces, fluidized bed reactors, and integrated direct-reduction systems for primary zinc facilities and EAF dust recycling operations.