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Polymetallic mine improves reconciliation and generates $320,000 additional value

Polymetallic mine improves reconciliation

Commodity Ore Grade Geology Powder Factor Location
Nickel / Copper / Gold Low – High Ultramafic layered intrusion 1.4 kg/m3  Europe

This Artic open-pit operation mines nickel, copper and gold.

  • Mineralisation is contained in hard Mafic rocks, which require a high powder factor to achieve optimum fragmentation
  • Benches are 12 metres and mined in a single pass
  • The site contains low and high ore grades

Challenges

Poor reconciliation between the reserve model, recovered tonnes and mill grades
  • Ore loss, dilution and misclassification resulting from the blast energy, generated by the high powder factors, moving the ore boundaries 10 – 20 m (32 – 65ft)
  • The mine had experienced poor reconciliation against forecast grades
  • Visual ore control is not possible

Solution

The BMM System accurately measured blast movement and translated post-blast dig lines
  • 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, misclassification and dilution that would have occurred without monitoring

Results

Improved reconciliation and recovered US$320,000 in one blast

Accounting for blast movement improved reconciliation variance:

  • Recovered tonnes variance improved from 3%1 to 1%
  • Mill grade variance improved from 13 – 16% to 2 – 5%

In an example blast, the mine minimised ore loss and misclassification. Significant movement occurs within all blasts. Variation of ±50% from the mean horizontal movement is common, and occurs at this mine. In this blast:

  • Measured horizontal movement ranged from 10 – 20 m (32 – 65ft) and heave of up to 3 m (10ft)

Accurately accounting for blast movement in this blast:

  • Maximised ore yield—an additional 7,7002 tonnes of Ni ore valued at US$320,0003 was recovered (avoided 5% ore loss)
  • Prevented misclassification of 30,000 tonnes (21%) of ore

1. Company supplied data
2. Numbers are rounded
3. Calculated at a commodity price of US$11,000 per tonne Ni

Accounting for blast movement added US$320,000 value—in one blast

Polymetallic mine improves reconciliation and generates $320,000 additional value