Screening-Level Conceptual, Stoichiometric, and Scenario Assessment of Sulfur-Emission Valorization in Coal-Fired Power Plants in Türkiye

This study presents a screening-level conceptual, stoichiometric, and scenario assessment of a pathway linking sulfur dioxide (SO2) capture from coal-fired flue gas to sulfuric acid production and the downstream reaction of sulfuric acid with pretreated scrap aluminum. A regenerable sodium sulfite (Wellman–Lord) capture route, followed by gas polishing and drying, catalytic SO2 oxidation, controlled SO3 absorption, acid conditioning, and an Al–H2SO4 reactor, is used as the reference configuration. The sulfur balance distinguishes sulfur in coal, ash retention, gaseous SOx, SO3/acid mist, absorber inlet and stack slip, captured sulfur, regenerated sulfur, and sulfate purge. Under the central assumptions, 1 t of sulfur in coal yields 0.849 t of recovered sulfur equivalent, 2.599 t of H2SO4, 0.477 t of aluminum feed, 2.419 t of anhydrous-equivalent Al2(SO4)3, 4.240 t of commercial aluminum sulfate on a 17 wt% Al2O3 basis, and 42.4 kg of H2 at 80% aluminum conversion. The upstream base-energy screen is 3.3–7.2 GJth and 0.18–0.45 MWhe per tonne of sulfur in coal. Diluting the acid to the selected 0.5–1.0 M aluminum-reaction window and subsequently producing a 17 wt% Al2O3 product creates a minimum water-removal load of 21.6–47.6 t and a latent-heat floor of approximately 49–108 GJth/t S. Retail prices are replaced by 2024 customs unit values, and internal-acid-production and sulfuric-acid-opportunity-cost boundaries are evaluated separately. In the central opportunity-cost case, the H2 value must reach approximately 6.9 USD/kg merely to balance material values before CAPEX, OPEX, energy, purification, transport, and environmental-compliance costs. The Afşin–Elbistan A case is treated as a full-design-throughput illustration based on an historical 18 Mt/y coal requirement, not as a measured current operating average; coal sulfur is tested over 1.0–2.5 wt%. The aluminum step is restricted to cooled and diluted 0.5–1.0 M H2SO4 at 40–60 °C, and direct H2 production from 96 to 98 wt% acid is not assumed. Plant-specific capacity factor, time-matched coal assays, flue-gas flow, oxygen-corrected stack data, reaction kinetics, gas purity, and product quality remain to be verified. The integrated sustainability screening indicates conditional circular-economy potential rather than a demonstrated sustainability advantage: sulfur recovery must be weighed against energy and water demand, sulfate purge and wastewater, diversion of recyclable aluminum from remelting, hydrogen purification, and market-scale product offtake. The pathway therefore remains a research hypothesis requiring experimental validation, process simulation, techno-economic assessment, comparative life-cycle assessment, safety analysis, and market verification.