Nkomati Nickel Mine – Timing flexibility

Highlighting the fact that electronics enable the blast to be fine tuned to suit any operational requirement.

Challenge
As an underground open-stoping operation, Nkomati Nickel Mine, situated 40km east of Machadodorp in Mpumalanga Province, prediction rates are typically 47,000 tons of ore and 3,000 tons of waste.  It had a vertical slot pass which connected drives in the hanging wall which were 15m high, meaning, conventionally, that a number of smaller blasts would be undertaken to create a 15m long slot.  This proved to be time consuming and also posed a safety risk.

Solution
AEL was approached and the pass was excavated through one single blast instead of succession of smaller blast.  The cut holes were timed with a 2,000ms delay to slow down the shot and enable sufficient breakage while the easers and perimeters followed with a fixed 250ms delay interval.

Outcome
Cut holes could be slowed down and provide plenty time for the broken rock to move and create a free face.  Safety and overall cycle times were improved.