Every day at 4am, the Winstone Aggregate’s Belmont quarry fires up, getting ready to supply the booming demand for aggregate in the Wellington Region, which reaches an average monthly production rate of 70,000 tonnes. 

To enable it to better serve the demand in the region, Belmont has been transforming itself over the past few years.  

This has included the removal of large amounts of weathered greywacke to the large roading project in the area which has opened up the ability to quarry increased volumes of un-weathered greywacke (‘blue rock’) from the quarry, that otherwise would have taken longer to expose. 

Other initiatives have included stripping, investment in plant, and people and traffic management to cope with the increased demand. 

Winstone Aggregate’s Wellington Quarries Manager Shane Hagai says the benefits of the buoyant market in recent times has allowed the up-scaling and upgrading of the quarry. 

“We’ve brought in new staff and trained them up on new and different equipment,” he says. “It’s really given the quarry a lift.” ​

“Some of the hard fill and weathered greywacke we have been supplying to the market has been material we may have stripped otherwise, and we have also kept stripping on top of that.” 

Evolving to the north 

Shane says pre the Covid-19 Level 4 lockdown they started stripping on the northern face and moved about 180,000 m³. 

Over time the mine plan takes the quarry northwards to the northern boundary. A new haul road is to be built for a more efficient route down from the Firth block to the processing plant. 

Extraction on the southern face has stopped and a levelled area below is being turned into an area for a product bay, to deal with customer traffic flows that were otherwise very congested. 

Hagai says previously trucks would circle closer to the processing plant components for pick-up, so this new move allows better separation of customer and quarry vehicles. 

Quarry operations benefit from plant upgrades  

In terms of year-round steady-state production, concrete sand demand is a big driver for the quarry, feeding the adjacent Firth concrete plant and others in the vicinity on demand. 

A new $900,000 Rocktec sand plant was commissioned last year and has been performing well, says Shane. 

One of the challenges of manufacturing sand is the output of by-product in the form of chip. “We make the sand and the chip comes with it.” 

The new plant has increased efficiencies measurably, doing a lot of the sand blending which was previously handled manually using a loader. 

Another of the upgrades at the quarry has been the installation of a new two-lane weighbridge providing a one-way traffic flow system to deal with the high volume of trucks passing through. This was accompanied by a new driveway, wheel wash and improved computer system for operating the weighbridge. 

In the spirit of innovation and the drive for greater efficiencies the Belmont team has also trialled different plant modes to increase yields, with a good degree of success. 

“This has resulted in us being able to produce far less by-product and we are at the point now where we can produce just sand without any by-product using a sand-only mode.” 

During the month of October last year, the quarry was able to reduce plant hours from 6am–9pm to 6am-5pm.  

Shane says despite the reduction in plant time they were able to produce more product, simply through being smarter.  

The next big plant upgrade would be the secondary plant in the next couple of years or so.