Zinc mine added US$780,000 of value in one blast

Zinc mine added US$780,000 of value in one blast

zinc-north-america-mine

Commodity Ore Grade Geology Powder Factor Location
Zinc High Shale-hosted 1.6 kg/m3 North America
This operation, located in the Arctic Circle in northwest Alaska, is one of the largest zinc producers in the world. It also produces lead and silver.
  • Shale-hosted zinc, lead, and silver deposits are mined in a single pit with four blasts per week
  • Drills and blasts 25 ft. (7.6 m) benches that are mined in a single pass
  • Ore/waste or ore/ore boundaries are visually controlled

Challenges

Ore loss and dilution due to difficulty in visually identifying ore boundaries
  • Difficulty in visually identifying low and medium grade ores bounded by Baritic material
  • Misclassification of low and medium grade ores (i.e. medium grade ore is stockpiled as low grade or low grade ore is sent to the mill)
  • Visually identifying high grade ore boundaries does not fully account for blast movement, resulting in significant ore loss

Solution

BMM System accurately monitors blast movement of ore boundaries and translates ore polygons
  • Blast movement monitors (BMMs) were installed in monitoring holes throughout the shot
  • Installation and detection as per site standard operating procedures
  • BMM Explorer software calculated new dig lines, and areas of ore loss and dilution that would have occurred without monitoring

Results

Additional US$780,000 value was recovered by using the BMM System instead of visually adjusted ore line control
Significant movement occurs within all blasts. Variation of ±50% from the mean horizontal movement is common and occurs at this mine.
  • Measured horizontal movement ranged from 6 ft. to 43 ft. (2 to 13 m) and vertical movement up to 22 ft. (6.7 m)
As a result of accounting for actual blast movement instead of relying on visual controls, this mine:
  • Avoided 7% dilution—3,500* Tons of waste were not sent to the mill
  • Reduced misclassification—correctly treated 800 Tons of low grade ore that would have been stockpiled as high grade
  • Maximized ore yield—recovered an additional 2,900 Tons of ore, valued at US$780,000,** from this blast, avoiding 3% ore loss that would have occurred using visual controls
* Numbers are rounded
** Calculated at various $/Ton grades, provided by mine personnel
Accounting for blast movement recovered 2,900 Tons of ore, valued at US$780,000
North America-zinc-blast-map
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