The tailings optimization and water management scoping study undertaken by Hatch for Xstrata Copper’s Kidd metallurgical site included a critical review of existing infrastructure and operations and maintenance practices with consideration given to the limited remaining operating window at the mine and the closure/post-closure periods. A water balance and hydrology study was completed to allow optimization of treatment costs as a trade-off between treatment plant capacity and provision of additional pond storage for the attenuation of peak flows.
Potential installation of a new high-density sludge (HDS) treatment plant was evaluated in comparison with modifications to the existing conventional lime precipitation process. Future impact on lime demand was projected in association with key management decisions to progressively close and rehabilitate inactive tailings disposal areas and cease co-disposal of jarosite.
Strategies were also recommended for thiosalt management and improved control of pond pH. Improvements to pond settling of particulates and precipitated metals were identified via application of a computational fluid dynamics (CFD) pond model. The scoping study also considered opportunities for source reduction of flow and acidity loadings from the concentrator.
Hatch conducted engineering studies for the scoping study at Xstrata Copper’s Kidd metallurgical facility. Major project deliverables included:
- Interviews with key stakeholders and review of plant and tailings management area (TMA) performance data to identify opportunities for improvement
- Hydrology study and estimate of run-off flow for design storm event (100-year spring freshet)
- Lime demand projections
- CFD model to characterize solids settling behaviour in shallow pond and permit investigation of engineering and management options to enhance performance
- Equipment list and sizing
- Capital (CAPEX) and operating (OPEX) cost estimates
- Scoping study report and input to Xstrata gate review process.
- Trade-off study comparing HDS treatment to a conventional lime precipitation process (NPV evaluation)
- Optimization of the combined costs for treatment and hydraulic storage capacity
- Lime demand projections considering progressive TMA closure and elimination of jarosite
- Recommended thiosalt management strategy
- CFD model developed to describe solids settling behaviour and flow patterns in shallow pond
- Plan to deal with operationally challenging peak flows during spring snowmelt in a manner consistent with economic realities and the remaining life of mine
