Our Changing World: High powered magnets, and making steel with hydrogen

New Zealand researchers are pioneering a groundbreaking approach to steel production that could significantly cut carbon emissions. At the Paihau Robinson Research Institute, part of Victoria University of Wellington, Professor Chris Bumby and his team have spent nearly ten years exploring the potential of hydrogen to replace coal in the steelmaking process. Their work focuses on utilizing New Zealand’s unique black iron sands, which are rich in iron but also contain titanium dioxide, making them unsuitable for traditional blast furnaces. The current steelmaking process relies on coking coal, iron oxide, and limestone in a blast furnace. Oxygen is removed from the iron ore, resulting in molten iron and slag. This method, though effective, generates substantial amounts of carbon dioxide. In New Zealand, the challenge is compounded by the nature of its iron ore, black sands found along the North Island’s West Coast. These sands, while valuable for steel production, contain titanium dioxide, which has a very high melting point and disrupts the conventional processing methods. Instead of relying on traditional techniques, New Zealand has long used a custom two-step process to extract iron from these black sands. The first stage involves reducing iron oxide using heat and coal to produce direct reduced iron. The Robinson Research Institute team has focused on replacing coal with hydrogen in this critical step. By doing so, they aim to eliminate the carbon dioxide byproduct and instead generate water. If green hydrogen is sourced, this shift could drastically lower the environmental impact of the process. To explore this alternative, the researchers have constructed a series of progressively larger reactors. Starting with small-scale experiments, they have moved toward lab-sized pilot reactors capable of producing approximately 10 kilograms of direct reduced iron per hour. Despite the similarity in appearance between input and output materials, the transformation represents a major breakthrough in sustainable metallurgy. The team continues refining the process to ensure the produced iron can be effectively integrated into the broader steelmaking cycle. Senior research engineer Ben Rumsey notes that while the end result appears unchanged, the underlying changes are profound. Scaling up reactor operations has enabled the group to generate more direct reduced iron, which they can then melt and analyze for chemical properties. Since hydrogen replaces carbon, the final product differs from standard pig iron, necessitating adjustments in later stages of steel production. A notable advantage of the hydrogen-based method is its speed. Traditional steel mills require about 10 hours to transform iron sand into direct reduced iron. With hydrogen, the same conversion can occur in roughly two and a half minutes. This efficiency could provide a competitive edge in industrial applications, enabling higher throughput and potentially reducing energy consumption. As the research progresses, the focus remains on optimizing the process for scalability and practical implementation. The findings highlight not only a path toward lower emissions but also a potential revolution in how steel is manufactured, leveraging New Zealand’s natural resources in a more environmentally friendly manner. The ongoing work promises to reshape the future of steel production, offering a cleaner alternative to the industry’s longstanding practices.