European multi-metal mine improves ore recovery through blast movement monitoring

blast at polymetallic mine

Commodity Ore Grade Geology Powder Factor Location
Ni, Zn 0.33% Ni Equivalent Disseminated 0.95 kg/m3 Europe

One of the largest metal producers in Europe, this low-grade, low-cost operation mines nickel, zinc, cobalt and copper. With a strong focus on continuous improvement, the mine is also establishing itself as a best-practice leader in sustainable mining.

  • The deposit is a large low-grade, black-shale hosted, polymetallic sulphidic resource
  • Blasts are fired in 15 m benches
  • Metal extraction uses an energy-efficient leach-heap process

Challenges

Unaccounted blast movement increased the risk of ore loss and lower metal recovery
  • Mine operations were estimating the extent of blast movement and its effect on ore boundaries
  • Loading maps were being modified by eye and grade control had no way to confirm that the adjustments were correct
  • Continuous improvement required precise adjustment of ore contacts to minimise waste

Solution

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 and dilution that would have occurred without monitoring

Results

Accurate adjustment of blast movement recovered €211,0001 additional value in one blast

Mine operations were able to accurately adjust loading maps to account for blast movement and minimise ore loss.

An example blast demonstrates the ore loss and dilution that would have occurred if blast movement was not accounted for. Significant movement occurs within all blasts. Variation of ±50% from the mean horizontal movement is common, and occurred in this blast:

  • Measured horizontal movement ranged from 11.2 – 41.7 m

As a result of accurately accounting for blast movement, this mine:

  • Maximised ore yield—6,9002 tonnes of ore, valued at €211,285, were recovered
  • Avoided dilution—11,3002 tonnes of waste were diverted from the mill, saving €136,000 in unnecessary milling costs


1. Numbers are rounded.
2. Calculated by BMM Explorer.

This blast map shows pre- and post-blast ore polygons, and areas of ore loss (pink) and dilution (brown).  In this blast, accounting for blast movement added €211,285 of value.


Definitions

Ore loss occurs when material containing grade (ore) is incorrectly sent to a waste dump.

  • When a cost is given for ore loss, it is the sale value of the metal (copper) recovered from this ore (i.e. ore tonnes x grade x recovery rate x metal price)

Dilution occurs when waste is unintentionally mined with material containing ore and sent to the mill.

  • When a cost is given for dilution, it is the cost of processing the waste material through the mill