4.5 Best practice blasting

Using electronic initiation of blasts rather than traditional shocktube detonators significantly reduces vibration impacts caused by the blast. Electronic detonation has been shown to:

  • reduce the maximum vibration readings
  • reduce the number and intensity of high vibration readings
  • increase the uniformity of the blast
  • control the vibration frequencies to minimize the low frequencies
  • increase dig rates.

Electronic detonation allows for precise timing of initiation of each charge. This reduces the vibration levels. This system has been extensively used at Newcrest’s Telfer mine.

CASE STUDY: Comparison of electronic and traditional detonators

A trial was carried out at AngloGold Ashanti Sunrise Dam open-cut gold mine, where two blasts were carried out, one using electronic detonators and one using shock tube detonators. The design parameters of the two blasts remained constant. The selected location of the two blasts was chosen so that the geology was as consistent as possible. Blast design parameters, including initiation timing, were determined by engineering to suit the geology and kept constant for both shots.

The results of the blasts showed:

  • Muck pile profile and swell
    • The electronic blast increased the fragmentation on the surface of the blast.
    • The electronic blast achieved a much more consistent heave.
  • Productivity—A 16 per cent increase in dig rate was achieved with the electronically initiated blast in comparison to the shock tube-initiated blast.
  • Fragmentation—The electronically initiated blast achieved an improvement in overall fragmentation.
  • Crusher—The electronically initiated blast achieved higher average throughput and maximum throughput than the shock tube-initiated blast.
  • Vibration analysis—The vibration readings achieved from the electronically initiated blast were more uniform though not significantly lower.

Electronic blast muck pile.

Shock tube blast muck pile.

Shock tube (NONEL (c)) and electronic (HotShot (c)) geophone vibration comparison.

Full details of this case study can be found in the technical paper: Vaughan, M, Hall, E, Varga, D, Billing, G & McSweeney, K 2007, ‘Blast improvements with electronics at Sunrise Dam Gold Mine’, paper presented at the EXPLO Conference, Wollongong, NSW, 3–4 September 2007.

CASE STUDY: Ventilation shaft in a residential area

Sinking a 315 metre ventilation shaft is challenging enough—when you place that project in a residential area of a regional city, you really need to do your homework.

Planning and consultation

LGL Ballarat started planning for the ventilation shaft in 2006, well before the planned construction commencement date of July 2006.

With some residents as close as 60 metres from the worksite, significant effort was put into planning to minimise the impact on the neighbours. Extensive consultation with the community was undertaken prior to, during and after each phase of construction.

Initial consultation (letter drop) was followed up by personal contact with the closest residents and those with particular concerns. One-on-one consultation with the immediate neighbours, using diagrams of each phase, took place during the early planning stage. Each neighbour was asked whether they had any concerns; most were concerned about potential blast vibration, noise, work hours and dust.

The company has a long history of good community engagement, so many members of the community were interested in and supportive of the project. The information gathered from community surveys was incorporated into the final plans. For example, the site layout was changed to accommodate two neighbours, moving parking bays, installing visual screens to ensure car lights did not shine into the neighbour’s property and moving a tipping bay to reduce dust and noise impacts.

Letter drops and community newsletters were produced throughout the duration of the construction of the shaft. The site was also incorporated into the company’s public open day. Information supplied focused on describing current and upcoming activities and ensuring the community had an open line of communication with the company.

LGL Ballarat strives to minimise the impact on the community, rather than simply achieve the compliance limits set by regulators. For the shaft project, the company set internal targets well below compliance levels for blast vibration. For example, the internal limit for peak particle velocity was 3 millimetres per second, which was less than a third of the regulatory compliance limit of 10 millimetres per second.

Once the site preparation was completed and shaft works had begun, the community realised that the company was doing its utmost to ensure that all impacts were minimised. The company took all complaints seriously and modified practices to ensure constant improvement. The biggest reward for the project team came when the initial objectors became supporters of the project and acknowledged the consultation efforts undertaken. One comment from a regulator was ‘going beyond compliance is gold.’

Bird’s-eye view of the worksite in Ballarat. Source: LGL – Ballarat Goldfields.


Collected stormwater and recycled mine water were used as temporary dust suppressants and, although acceptable, did not deliver satisfactory results. Other technologies were trialled but, given the tight turning circles of heavy vehicles and a need for constant reapplication, they also failed to deliver satisfactory results. The only means of effectively reducing dust emissions was to lay asphalt in the car park, which the company did. In addition, sprinklers were engaged to reduce dust rising out of the shaft during blasting.


Research identified a locally produced recycled paper and concrete noise attenuation product that was ideal for the 6 metre-high compound walls. The compound housed activities such as the use of shaft winders and air compressors, rock dumping, truck loading and equipment handling. To ensure that there was no interruption to the neighbours’ power supply, noise-attenuated diesel power generators (like those used on film sets and at public events) were used. These generators were placed within a smaller compound with additional attenuation barriers, on the side of the project site furthest from neighbours. All vehicle-reversing alarm beepers were changed to low-frequency ‘squawkers’.

A noise monitoring officer visits a neighbour’s residence, with the sound wall visible in the background.


Several of the neighbours had concerns regarding the potential for cracking of their houses from the blast vibration. To provide assurance to these neighbours the company commissioned house inspections by a qualified independent building inspector, during the planning phase. Four investigations were undertaken prior to commencement and two during the project. These inspections and additional monitoring undertaken by the company gave residents peace of mind that there was minimal chance of damage occurring to their properties.

Consultation with the explosive manufacturers and peer review by independent blast experts ensured a high level of control over the blast design process. A decision to free dig the shaft with a small excavator to a depth of 70 metres, rather than blast, reduced the impact of near-surface blasting.

During times of blasting, electronic detonators were used to provide reliable timing of blast delays and a larger range of delays compared to the more commonly used initiation methods. This enabled blast vibration to be minimised and eliminated the use of blasting cord, which can be a source of blast noise. Three blast monitors with geophones and linear microphones were used during the project; two remained stationary while the third was used for reactive investigations at properties where the residents had blasting concerns.

One of the key learnings from the project involved the benefit of providing a spoken telephone text message service to warn residents immediately prior to blasting. Many of the residents were startled by the blast vibration and noise, and simply alerting them five minutes prior to firing alleviated this issue.

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