Quarrying & Mining Magazine

A nifty new plant


Stevensons’ Drury Quarry is one of the largest and most technically advanced in the country and amongst the biggest producers of aggregate in the Auckland region, supplying over a quarter of its needs.

QM_Nifty_New_Plant_2With over 100 years of quarry rock reserves, Stevensons’ Drury Quarry is well placed geographically to supply major new infrastructure projects and urban development in the Auckland and Waikato regions.

In terms of servicing, its pugmill and IANZ certified laboratory has set it apart from other quarries in the region for some time.

Now the quarry has commissioned a $7 million aggregate processing plant with a Kiwi-made vertical shaft impact crusher at its core.

We featured the all new VSI crusher, designed and made by Rocktec in Matamata, in the last issue of Q&M (October/November 2014) when members of the Waikato and Bay of Plenty IOQ held their AGM at Rocktec and got the first view of the machine (pictured) painted up in blue and white corporate brand colours. While Rocktec designed and built the exterior, the guts is made up of standard OEM and alternative rotors and shaft line assemblies that are interchangeable with existing manufacturers, including Metso distributed in New Zealand by Mimico.

Quarry manager Shane Toto at the small control box of the automated new plant that replaces the traditional row of buttons.
Quarry manager Shane Toto at the small control box of the automated new plant that replaces the traditional row of buttons.

The installed power is 300kW from two WEG 150kW motors. Features include an air transfer system to control dust.

“We are very happy with the finished result,” says Rocktec’s sales and marketing manager Jason Tapper.

“This prototype has been built on known parameters and we had no issues whatsoever with the commissioning – everything with the first inspection was as predicted.”

Unique technical details include good rotor access through large gull-wing top hatches and an interlocking chamber door. “The improved rotor access has proven very successful.”

These machines are now being built to order and customised to suit specific customer applications or specifications, with four more quotes out in the quarry community.

QM_Nifty_New_Plant_3Built to take a beating

The finished 200 tonne an hour plant is fully automated. As Steve Ellis, minerals executive, Stevenson Group says; “You can start it up in the morning and leave it alone all day.”

The system is run by a programmable logic controller (PLC) with all the latest automated software including emergency stops to criteria four and an electronic weigh scale that talks to the feeder.

The total system is made up of a 25 tonne hopper feeding the Rocktec VSI crusher, a Rocktec Avalanche 20×8 screen taking out a DAP product and then oversize travels direct from the screen to crusher. Graded chip is shot over to the last two screens for washing aggregate similar to 7 chip. They are both also Rocktec made screens.

Civil design is by Gia Ka-Ching Chung; foundation construction by Primer Construction; and site works by local contractor Adrian Tizard.

Steve says a lot of future proofing has gone into the set up.

QM_Nifty_New_Plant_4“This time we have galvanised all the catwalks and platforms to avoid rust in the long term, and the infrastructure is fully guarded to the latest specs.”

The company has also spent hundred of thousands of dollars on new guards on other machinery in the quarry.

“Since 2003 the regulations have changed and we are spending a lot of money upgrading plant and equipment based on pending changes next year.”

Even the bins have been given special long-term treatment.

“The concrete bin walls are extra strong and tapered and steel rails are cemented into floors to take loader bucket wear and avoid blow-out.”

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