This Arctic 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

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