π Case Study
Limestone Mine Neutral Drainage Management at Mount Read Complex (Tasmania)
Historic waste dumps containing carbonate-hosted Pb-Zn mineralization generating neutral metal leachate (Zn >15 mg/L, Cd >0.2 mg/L)
ποΈ Project Overview
Mount Read polymetallic mine rehabilitation (Tasmania), 2020β2024
π― Challenge
Historic waste dumps containing carbonate-hosted Pb-Zn mineralization generating neutral metal leachate (Zn >15 mg/L, Cd >0.2 mg/L)
π§ Design Approach
Sulfate attenuation capacity (SAC) enhancement via limestone-dolomite blending + constructed wetland polishing; geochemically constrained design using SAC testing and reactive transport modeling
π Design Diagram
AI-generated project design illustration
π Key Calculations
Required SAC
Ξ£(SOβΒ²β» load Γ residence time)
Result: 420 kg CaCOβ/t
Set minimum dolomite addition rate
Wetland HRT
V/Q
Result: 14.2 days
Achieved >95% Zn removal per USGS benchmark
π Results
Downstream Zn reduced from 18.3 mg/L to 0.4 mg/L; Cd from 0.31 mg/L to <0.005 mg/L; SAC-based cover remains functional after 3.5 yearsπ‘ Lessons Learned
- β’Dolomite outperformed limestone due to Mg buffering
- β’Wetland clogging occurred where SAC leachate pH dropped below 6.2
- β’SAC testing must include long-term (β₯90 day) leach cycles
- β’Geochemical zoning of waste piles improved material placement efficiency
- β’Real-time Zn sensors enabled adaptive wetland flow control
β Key Takeaways
- 1Dolomite outperformed limestone due to Mg buffering
- 2Wetland clogging occurred where SAC leachate pH dropped below 6.2
- 3SAC testing must include long-term (β₯90 day) leach cycles
- 4Geochemical zoning of waste piles improved material placement efficiency
- 5Real-time Zn sensors enabled adaptive wetland flow control