ToolFusion
📋 Case Study

Gold Mine Tailings Seepage Treatment & Gold Reclamation – Western Australia

Low Au (<50 ppb) but highly mobile due to cyanocomplexes; strict discharge limits (CN⁻ < 0.2 mg/L)

🏗️ Project Overview

Subsurface seepage from cyanide-leached tailings dam contaminating groundwater with CN⁻ and residual Au

🎯 Challenge

Low Au (<50 ppb) but highly mobile due to cyanocomplexes; strict discharge limits (CN⁻ < 0.2 mg/L)

🔧 Design Approach

In-situ reactive barrier (zero-valent iron + activated carbon) + ex-situ electrochemical stripping

📐 Design Diagram

Gold Mine Tailings Seepage Treatment & Gold Reclamation Western Australia | In-situ + Ex-situ Hybrid System Low Au (<50 ppb); Mobile CN⁻-Au complexes | CN⁻ discharge limit: <0.2 mg/L In-situ Reactive Barrier ZVI + Activated Carbon ZVI: 1.2 g Zn/g Au | AC: qₘ = 12.7 mg Au/g Tailings Seepage Treated Effluent Ex-situ Electrodeposition Energy: 14.2 kWh/g Au Recovered Au⁰ (solid) Discharge (CN⁻ <0.2 mg/L) CN⁻/Au(CN)₂⁻ Au⁰ recovery In-situ Barrier Electrodeposition Flow Direction Challenge Parameter

AI-generated project design illustration

📐 Key Calculations

ZVI Reaction Stoichiometry

2Au(CN)₂⁻ + Zn → 2Au⁰ + Zn(CN)₂ + 2CN⁻
Result: 1.2 g Zn/g Au
Sizes barrier media volume

Carbon Adsorption Isotherm (Langmuir)

qₑ = (qₘ·K·Cₑ)/(1 + K·Cₑ)
Result: qₘ = 12.7 mg Au/g AC
Predicts column service life

Electrodeposition Energy Use

E = (V × I × t)/(mass_Au)
Result: 14.2 kWh/g Au
Optimized voltage to avoid oxygen evolution

📊 Results

CN⁻ reduced from 1.8 to 0.09 mg/L; recovered 42.6 kg Au over 18 months; extended tailings dam life by 7 years

💡 Lessons Learned

  • •ZVI-carbon synergy prevented passivation
  • •Real-time cyanide monitoring prevented breakthrough
  • •Recovered gold offset 63% of treatment capex

✅ Key Takeaways

  • 1ZVI-carbon synergy prevented passivation
  • 2Real-time cyanide monitoring prevented breakthrough
  • 3Recovered gold offset 63% of treatment capex