AMC’s field trial and multivariate analysis established predictive relationships that enabled the results of 14 SAG mill comminution (SMC) tests to be extrapolated, using 12,529 sample assays from previous core and reverse circulation drill holes. Leveraging off existing resource drill hole data, saved time and money.
Hecla Limited engaged AMC to identify applicable open-pit and underground mining methods for the San Sebastian operation in Mexico. In collaboration with Hecla, AMC identified the scenario that best aligned with the client’s strategic goals and maximized project value. The mine went into operation following the results of this study. Stripping began in late 2015 and the three pits were successfully placed in operation in early 2016, and have subsequently met all of Hecla’s schedule and production goals.
The San Sebastian operation comprised four deposits that could be mined through a combination of open-pit and underground mining methods. The challenge was to identify the most appropriate mining method for each deposit and the transition point from open-pit to underground mining.
Following the results of the study, the mine went into production. Since then, it has generated more than $92 million in cash provided by operating activities less capital expenditures in 2016.*
* Hecla Mining Company 2016 Annual Report
AMC’s approach to assessing the optimal combination of open-pit and underground mining at San Sebastian focused on:
- Constant client collaboration.
- Geotechnical analysis and recommendation of pit slope angles, crown pillar requirements, and underground stope dimensions.
- Mining method options assessment based on AMC’s country-specific experience.
- Pit and stope optimizations.
- Determination of optimal open pit / underground interface and development sequence to sustain continuous production.
- Practical mine design, sequencing, and detailed mine schedules.
Company: Hecla Limited
Operation: San Sebastian
Location: Mexico, Durango state
Commodity: Gold and silver