Combining computational modelling with pilot-scale testing, Mintek is helping develop a more sustainable route to manganese alloy production.
Mintek, South Africa’s mineral and metallurgical research organisation, brings together detailed computer simulations and practical pilot-plant experience to support the development of the HAlMan process.
As a partner in the EU co-funded project HAlMan, Mintek contributes to developing and demonstrating a production route using hydrogen and aluminium as reducing agents to produce manganese and its alloys. The wider project aims to reduce the carbon footprint of production while making better use of ores, secondary raw materials and process by-products.
Understanding hydrogen pre-reduction
Mintek’s computational and numerical modelling work supports the hydrogen pre-reduction stage, during which manganese ore reacts with hydrogen before entering the subsequent smelting stage.
Inside the reactor, chemical reactions interact with gas flow, heat transfer and changes in the ore’s structure. Multiphysics modelling helps investigate these effects together and creates digital representations of the process.
Mintek’s published computational fluid dynamics research examines hydrogen reduction in a shaft furnace, including how gas transport and changes in the porous ore bed influence reduction. These findings provide information relevant to reactor design and operation.
Making models useful for plant applications
Detailed simulations require substantial computing power. The most sophisticated models rely on high-performance computing facilities, making them impractical for routine use in operating plants.
A central part of Mintek’s modelling work in HAlMan has therefore been developing reduced-order models. These simplified representations retain the essential physics while running orders of magnitude faster.
Faster models could support digital twins and process control systems, helping engineers assess operating conditions without repeatedly running a full simulation. Verification and validation ensure that the simplified models preserve the accuracy needed for their intended applications.
Why the controlling mechanism matters
Mintek’s modelling work has shown that the mechanisms controlling reduction can change as the reaction progresses.
Under the conditions studied, chemical reaction rates dominate initially. Understanding reaction kinetics is therefore essential to predicting how the ore responds when hydrogen is introduced.
As reduction proceeds, mass transfer and diffusion become limiting. The movement of gases to and from reaction sites increasingly determines how quickly the process can continue.
These changing constraints have practical implications for scale-up. A reactor limited by chemical kinetics presents different design and operating challenges from one limited by gas transport. Identifying the controlling mechanisms helps inform pilot testing and predict how larger vessels might behave.
Connecting modelling with pilot-scale demonstration
Mintek’s demonstration responsibilities include hydrogen pre-reduction of lump ore in a vertical retort, followed by smelting trials involving pre-reduced ores and high-carbon ferromanganese slag.
A pilot campaign completed in July 2024 smelted more than 3,600 kilograms of manganese-containing material in a 200 kW DC arc furnace, producing an alloy containing more than 70% manganese.
Further Mintek research, highlighted in November 2026, combined thermodynamic modelling, process simulation and furnace trials to investigate manganese recovery from high-carbon ferromanganese slag using recycled aluminium. This work provides additional evidence for recovering value from manganese-bearing industrial residues.
Together, these activities connect scientific understanding with the engineering evidence needed for scale-up. Detailed simulations investigate process behaviour, reduced-order models support potential plant applications, and pilot trials demonstrate performance under practical operating conditions.