Daunia mine, the open cut coal operation in the north-eastern state of Queensland, Australia, has broken the world record for the largest electronic detonator blast ever.

The blast saw 5 665 detonators in 2 683 blastholes fired using the AXXIS digital detonation system from BME.

The mine had last year set a previous record for the largest AXXIS-controlled blast to date, when it successfully initiated 4 303 detonators in a single blast to break 2.8 million cubic metres of overburden.

Situated in the Australia’s largest coalfield – the Bowen Basin – Daunia mine has taken advantage of the benefits of electronic detonation to conduct larger blasts; this generates greater operational efficiencies by reducing the number of mine stoppages that must take place every time blasting is conducted.

The mine also chose this technology in response to its faulty ground conditions. If not well controlled, faults tend to slide over each other during a blast; when using non-electric detonators, there is a possibility of the product being snapped by this movement of ground before it can be detonated, resulting in a misfire.

“These misfires are eliminated with electronics, as the detonator operates as a stand-alone entity the instant you push the ‘fire’ button,” says Trevor Grant, MD of the Australia-based blasting optimisation company Advanced Initiating Systems (AIS).

The latest record blast was prepared and carried out by Daunia mine staff using a single initiation point and one master control box.

[quote]The blasting team was initially trained and certified by AIS, who are supplied by leading explosives firm BME; both companies are subsidiaries of diversified agricultural, mining and chemicals group Omnia Holdings, which is listed on the JSE.

“The use of the AXXIS system and electronic detonators allowed the mine to better control and manage the shock waves and rock movement arising from the faulty ground conditions,” says Grant.

“The size and success of the blast demonstrates both the ease of use and the confidence that the client has in the system. Very few, if any, other electronic detonator suppliers empower clients to conduct blasts of this magnitude and complexity on their own.”

The AXXIS electronic delay detonators feature very high accuracy, as well as timing flexibility between detonations. The average depth of each hole in the blast was 19 m, and the explosive was initiated from both top and bottom.

In preparation for blasting
In preparation for blasting

“The improved control of the blast helps keep vibration levels down,” notes BME technical director Tony Rorke. “This in turn improves safety in the opencast mining environment, as high vibration levels can undermine the integrity of the pit-wall.”

To design the blast, the Daunia mine team used BME’s blast design software BlastMap III, which was developed as an integral part of the AXXIS system. The programme allows complex timing designs and analysis of the results for each blast, and has just been released in an updated, second-generation version – BlastMap GII.