While steel is ubiquitous, its refinement currently contributes 8% of the global CO₂ footprint, 64% of which originates from ironmaking. New sustainable ironmaking processes require insights into the fundamental science that complicates scalability due to competition between chemistry and sticking mechanisms that limit reactor performance. This talk will present our work studying the direct hydrogen reduction of the smallest magnetite particles representative of iron ore fines – particles of the 10-nm scale. Using X-ray diffraction at low temperatures, we observe the preferential formation of Wustite during direct H₂ reduction even down to 300ºC, with a chemical mechanism that divides into three stages of transport vs chemistry. By linking these results to small-angle scattering, TEM and X-ray ptychographic tomography, we illustrate how the mechanistic chemistry couples to specific regimes of new work. Our finding shed light on the coupling between chemistry and sticking dynamics at the nanoscale, offering an important starting point to establish multiscale process models.