Geochemical forecast of acid mine drainage to evaluate corrective action plans for mine reclamation
Conference
·
OSTI ID:613851
- GeoSyntec Consultants, Atlanta, GA (United States)
- Peabody Coal Company Midwest Business Unit, Graham, KY (United States)
A geochemical model was developed as part of the site investigation to characterize current geochemical conditions in coal refuse disposal areas and to support a modification to the reclamation plan at a closed underground coal mine in southern Illinois. The model provided significant insight into the geochemical processes which impact the development of a reclamation plan for the mine. Specifically, the geochemical model was designed to simulate the actual chemical reactions between infiltrating water and coal refuse and/or soil. The modeled acid mine drainage (AMD) was calibrated to observed conditions. New geochemical models were developed to predict the effectiveness of proposed reclamation activities on ground-water quality. Development of the geochemical model proceeded in two steps: (i) construction of a detailed conceptual model which accounted for all reaction paths; and (ii) computer geochemical modeling to confirm the validity of each reaction path using MINTEQA2 and PHREEQE. Mineralogical analysis of the coal refuse confirmed that pyrite was the mineral responsible for the AMD, therefore the conceptual model focused on pyrite dissolution and the generation of sulfate. The computer modeling accurately predicted the resulting sulfate concentrations in the AMD observed for all reaction paths in the conceptual model. Once the system was adequately characterized by a geochemical model, new models were generated and validated via comparison to ground water analyses, followed by computer modeling to forecast the impact of a range of corrective action scenarios on the ground water. The selected reclamation plan consists of hydraulic control of impacted ground water by pumping and construction of an enhanced cover system comprising a compacted clay liner overlain by a soil cover. This paper demonstrates how geochemical modeling is a valuable tool to use in evaluating and developing solutions for surface mine reclamation.
- OSTI ID:
- 613851
- Report Number(s):
- CONF-9705128--
- Country of Publication:
- United States
- Language:
- English
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