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Orica Offers Specialised BBS to Golden Bay Cement

Orica Offers Specialised BBS to Golden Bay Cement  

Orica Mining Service’s ability to offer BBS (Blast Based Services) solutions to ground vibration and air blast issues at the Wilsonville quarry was a vital factor in recent contract negotiations with Golden Bay Cement. Orica has enjoyed a productive long-term relationship with Golden Bay Cement, one of New Zealand’s largest cement manufacturers and suppliers. It's Portland manufacturing plant is located near Whangarei and its Wilsonville quarry is based north of Hikurangi.

The Wilsonville site has the higher grade and more valuable limestone, but poses the greatest environmental issues because of its proximity to neighbouring properties. It is located around 500 metres from the outskirts of Hikurangi.

‘A big issue at the Wilsonville quarry is improving the existing controls around ground vibration,’ says Orica’s Account Manager Craig Pledger.‘It’s a challenging project. Proximity to neighbours means that ground vibrations during blasting are a sensitive environmental issue. We’rereducing ground vibration by using an electronic blasting system and vibration prediction, based on maximum instantaneous charge and distance from neighbours. The closer we get to neighbours, the smaller the charge.


‘We’ve worked closely with quarry managers analysing blasting resultsand the Wilsonville quarry is compliant with environmental requirements.However, we’re now working on productivity aspects of our contract. We’re aiming to blast the limestone rock into smaller pieces (improve the fragmentation), making it easier to dig and reducing the reliance on hydraulic rock breakers for secondary breaking. The improvement in the fragmentation is based around accurate explosive distribution through the different geological bands, accurate explosive charge weights and timing of the blasts using i-kon™ electronic detonators.The aim is to achieve a balance between being environmentally compliant and improving efficiencies,’ says Craig.

‘Ground vibrations have been controlled to date, but at a high priceto Golden Bay Cement,’ says Orica’s Senior Technical Services Engineer Kane Inwood. ‘It has involved a substantial amount of three-deck charges within single blast holes, as well as double-decking – two-deck charges in a single blast hole.

‘By applying the latest technology – advanced vibration modellingwith our Monte Carlo software – we can achieve better control onground vibration at Wilsonville. We will potentially be able to make blast predictions more consistent. This will allow us to optimise ourblasting in the pit, which may enable us to reduce costs. The datafrom the advanced vibration modelling will potentially let us reducesome of the triple-decking of blast holes to double decks, and also reduce some of the current double decks to single decks. We need a model which can produce a high confidence outcome that will allow us to achieve this. Orica has already created Monte Carlo models whichhave performed well at other mines and quarries.

‘Orica is looking to reduce Wilsonville’s overall blasting costs and to increase rock fragmentation. Reducing the reliance on excavator mounted hydraulic rock breakers will reduce our client’s initial costs,as well as providing other long-term benefits.‘One of our key targets will be to reduce the number of hours orthe number of machines required for secondary breakage. We wantto reduce the number of excavator-mounted hydraulic rock breakers from two to one, providing an immediate cost benefit,’ says Kane.

At Golden Bay Cement’s Portland quarry, Orica has loaded blasts volumes up to 120,000 tonne of production rock using the two MMU (Mobile Manufacturing Units) based at the Waitawa site delivering the new Centra™ Gold bulk emulsion system.‘Orica delivers a solutions-orientated service, providing and selling what you need,’ says Richard Frost, Golden Bay Cement Quarries Manager. ‘The use of i-kon™ electronic detonators have proved to be a great success in ensuring blast vibration compliance under difficult blasting conditions. Looking into the future, BBS appears to offer us opportunities that can be shared to give both parties a competitive edge in tough economic conditions.