Soledad Mountain Mine is a gold-silver mine located near the town of Mojave in southern California.

• The mine uses conventional open pit mining methods, and cyanide heap leach and Merrill-Crowe processes to recover gold and silver from crushed, agglomerated ore.
• The primary ore types are porphyritic rhyolite, flow-banded rhyolite, pyroclastics and porphyritic quartz latite.
• The East Pit mines 20-foot (6 m) benches in one pass.

Challenges

Narrow host-vein geometries presented challenges to mine operations due to a high risk of ore loss and dilution

• The extent of blast movement and its influence on ore zones was estimated
• Designed ore-waste boundaries could not accurately account for blast movement
• A buffer zone of material surrounding ore zones, incorporated to account for movement, was sent to the crusher

Results

Improved mining efficiency and stakeholder value
Average per-blast savings estimated at US$55,000

Within the first year of mining, Golden Queen Mining Company implemented blast movement monitoring. Soledad Mountain Mine’s results indicate a significant improvement in recovered Tons, estimated at US$55,000¹ average value per blast, through:

• Avoiding waste processing, and
• Mitigating the effects of ore movement in a narrow, vein-hosted gold/silver deposit

An example blast (shown right) demonstrates measured ore movement and potential savings at the East Pit.

Significant movement occurs within all blasts. Variation of ±50% from the mean horizontal movement is common and occurred in this blast.

• Measured horizontal movement² ranged from 4.5 –10.5 ft (1.4 – 3.2 m) and vertical movement of up to 5.3 ft (1.6 m)

As a result of accurately accounting for blast movement within one blast in East Pit, Soledad Mountain Mine:

• Improved recovered value by an estimated US$69,195^2,3
• Increased ore yield by 4,047 Tons (3,671 tonnes) and avoided 3% ore loss

* Average grade of ore polygons;
1. Golden Queen supplied data;
2. BMM System-measured blast movement;
3. Calculated at a gold price of US$1,350/oz.