Hydrogen plasma as a high-efficiency reducing agent for green metallurgy

Against the backdrop of the carbon emission reduction goal, the metal metallurgy industry—primarily reliant on carbon as a reducing agent—faces significant pressure. While numerous studies and projects have explored hydrogen (H 2 ) as an alternative reducing agent to achieve this goal, its low reducing power fails to meet the required metallurgical demands effectively. As a derivative of H 2 , hydrogen plasma (HP) exhibits high reactivity, enabling it to reduce most metal oxides. This paper focuses on comparing H 2 and HP across four metallurgical applications: metal metallurgy, alloy preparation, metal refining and purification, and recovery of valuable metals from waste—highlighting the superior performance of HP in metallurgy. It also summarizes the impacts of existing HP metallurgy process parameters, providing valuable references for larger-scale trials. Additionally, the paper elaborates on representative current hydrogen production technologies, both fossil fuel-based and renewable energy-driven, to learn about the developmental status of hydrogen generation. The findings indicates that the high temperature and reactivity of HP enable it with greater efficiency and operational simplicity compared to H 2 in metallurgy process. For larger-scale trials, the following factors are particularly critical: the balance between input power and feed material, melt flow, and reactor design (especially the plasma torch). Furthermore, Optical Emission Spectroscopy (OES), process simulation, and artificial intelligence should be leveraged to enhance understanding of HP metallurgy mechanisms. • Renewable-driven hydrogen production supports sustainable HP metallurgy. • HP enables efficient metal reduction and purification with lower activation energy. • HP allows faster and simpler material preparation compared to H 2 processes. • Arc stability and melt control caused are hindering pilot-scale trials of HP.