Integrated Mathematical and Physical Modelling of SaltIons Leaching from Coal-Mining Waste: Implications for Ecological Safety and Civil Protection.

Abstract

Coal-mining waste heaps represent a significant source of dissolved salts that can be mobilised by precipitation, posing risks to ecological safety and civil protection. This study focuses on the Chervonohrad Central Concentration Plant spoil heap in western Ukraine, where both thermally altered and unaltered argillite were tested. Laboratory column experiments were performed on 100 g samples flushed with deionised water to simulate leaching under controlled conditions. The cumulative leachate volumes reached approximately 432 L, allowing quantification of total dissolved solids and ionspecific contributions. We flushed 100 g columns for 24 h at 300 mL·min⁻¹ (8.5 L recirculated; ≈ 432 L passed), which yielded final filtrate total dissolved solids of 462 vs. 185 mg·L⁻¹ for burnt and unburnt argillite and cumulative leached masses of 3.93 vs. 1.57 g (≈ 2.5× higher for burnt). Early-time contrast was also strong: after 2 h (≈ 0.7 L), burnt reached 183 mg·L⁻¹ vs. 50 mg·L⁻¹ (≈3.7×). Physical observations were combined with a mathematical modelling approach to establish a precipitation-response relationship linking annual rainfall to total dissolved solids release. The results indicate a strong linear increase of annual salt release with precipitation, with burnt materials exhibiting markedly higher fluxes. This integrated framework demonstrates how laboratory data and simple models can be applied to anticipate pollutant releases, supporting ecological safety and informing civil protection measures in coal-mining regions prone to hydrological extremes