Mining Studies
Costerfield Technical Report
Commodities
Client
Client Mandalay Resources
Location
Heathcote, Australia
Work Conducted
NI43-101 Report
Costerfield Technical Report
Mining Plus was engaged by Mandalay Resources to provide Qualified Persons (QPs) for an in-depth review and certification of the Costerfield Property's 2021 Technical Report. The project included validating geological data, estimating Mineral Reserves, and updating the mine plan for the Costerfield gold-antimony deposit in Victoria, Australia, following NI 43-101 and CIM standards.
CHALLENGES
The Costerfield Property presented several technical and logistical challenges. The narrow, sub-50 cm gold-antimony veins required precise resource estimation methods to ensure economically feasible mining. Additionally, Mandalay’s historical resource conversion from Inferred to Indicated categories needed further accuracy for sustainable planning. Operating within a constrained underground environment with narrow vein deposits also demanded rigorous mine planning and cost controls. Ensuring compatibility of the Brunswick Processing Plant with anticipated LoM (Life of Mine) ores while maintaining high metallurgical recovery posed an ongoing challenge. The cost-effective exploration and production process needed refinement to maximize output and reduce depletion rates.
SOLUTIONS
Mining Plus developed a comprehensive solution involving a detailed review and validation of geological data using the acQuire™ GIM system. A 2D accumulation estimation method with ordinary kriging interpolation was applied, tailored to the narrow vein structure of the Costerfield deposit. To optimize extraction, we recommended using long-hole stoping with cemented rock fill for improved selectivity and dilution control. Additionally, Mining Plus provided insights into increasing operational flexibility by incorporating Net Smelter Return (NSR) analysis, identifying high-value material. The updated 2021 resource estimates accounted for the improved processing recovery algorithms for the Brunswick Plant, ensuring optimal resource utilization.
OUTCOMES
Mining Plus’s work resulted in a 57,000-ounce net increase in Proven and Probable gold reserves and minimized antimony reserve depletion to only 2,200 tonnes, following 36.3 km of exploration drilling. The enhanced resource estimation model provided a reliable framework for future production planning, with validation confirming excellent agreement between production data and the block model. The revised metallurgical recovery projections and NSR-focused planning recommendations set a pathway for further productivity gains. By closely managing activity costs and operational bottlenecks, Mandalay Resources is positioned to boost Costerfield’s profitability, enhance resource conversion rates, and improve overall project economics.
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