Updating the U.S. Iron and Steel Material Flow Sankey Map for 2023: Upstream Mining Detail and Integration With Planning Models

This paper updates the national-scale Sankey diagram of U.S. iron and steel material flows for calendar year 2023 with expanded granularity in upstream mining, beneficiation, and ore preparation. The accounting reconciles iron ore and agglomerates, iron metallics including DRI and pig iron, scrap collection and preparation, ironmaking and steelmaking routes (BF-BOF and EAF), secondary metallurgy, continuous casting (slab, billet, bloom), downstream rolling and finishing, end-use allocation, and trade in intermediates and products. We apply a Bayesian material flow reconciliation workflow that combines heterogeneous observations with uncertainty and feasibility constraints (node mass balance and non-negativity), producing a reconciled posterior distribution for each flow. The reconciled 2023 network indicates a BOF-route net casting throughput of 23.7 Mt and an EAF-route net casting throughput of 54.5 Mt, defined as steel sent from secondary metallurgy to casting excluding internal continuous-casting scrap recirculation (shown as route-specific loops in the Sankey). EAF metallic input is dominated by scrap at 49.1 Mt and complemented by low-residual metallics, including 5.0 Mt domestic DRI, 3.1 Mt imported DRI, and 2.2 Mt imported pig iron to EAF. The upstream update quantifies pellet allocation of 16.1 Mt to blast furnaces and 4.2 Mt to direct reduction. Posterior uncertainty is concentrated in scrap routing and loss estimation. Derived indicators computed from reconciled values include a combined BOF-plus-EAF recycled content of 0.7, and a scrap export rate (share of scrap disposition exported) of 0.2. The resulting mass-balanced dataset provides a national reference for year-to-year comparison, identification of material bottlenecks, assessment of trade dependence by production stage, and coupling of material constraints to energy, emissions, and capacity-planning analyses. Relative to earlier maps, the 2023 update preserves a consistent high-level process taxonomy while expanding ore preparation detail (fines/beneficiation/agglomeration) to better support planning-model integration.