Stevenson’s Drury quarry, now 80 years in operation, is a case study in the modern use of flexible modular plant and conveyor systems, mostly run on electricity. In March, Alan Titchall was a guest with the IOQ’s tour of the quarry.
Our tour started mid-afternoon under a beautiful autumn sky at the huge Stevenson quarry area near Drury that now features Fulton Hogan’s Asphalt Plant and a network of lane-concrete roads and roundabouts servicing massive new warehouses and depots.
I got lost after failing to read the directions that came with the invitation (having been there eight years ago and thinking I knew the entrance). The entrance to the quarry pit has moved and is constantly moving in a planned development that includes another extraction site called Sutton Block.
But I arrived in time to join dozens of IOQ members tooled up in our site gear to be bussed in two lots to the top of the quarry pit, then to the new tertiary crushing plant designed and built by Mimico with Metso and Superior products, and then back to the main office for presentations from Kurt Hine (Stevenson Aggregates) and Garth Taylor from Mimico before enjoying a causal buffet dinner.
Owned by Fulton Hogan since 2018, the scale of this operation in terms of surrounding land is massive. Plans include opening a neighbouring quarry on Sutton Block with a 240-million-tonne resource ‘over the other side of the hill’ that will be consented soon.
Meanwhile, the original pit had an ‘opportunity’ to revalue its extraction based on learning from overseas, using modern equipment that provides both flexibility and savings, and even provides a blueprint for other Stevenson quarry sites.
The Drury pit is now 45 metres below sea level, with plans to go down to 75 metres. The edge of the quarry has been pushed north over the past five years as far as it will go, and now Stevenson is pushing the quarry back to final faces on the western side, creating lovely wide benches and working from the top down, while reaching north-west to where the primary office is. The aim is for 1500 tonnes an hour of primary processing capacity across two primary plants with step-by-step crushing equipment and conveyor belts on a ‘movable’ structure.
“We’re going to have less equipment on site, which is easier to manage, with lower cost of production,” says Kurt Hine, the General Manager Aggregates, at Stevenson.
The first step in the new operation involved moving from diesel to electricity – which is estimated to be about a third of the energy cost – and using excavators to move material up from the face to primary crushing and screening. The quarry operates around 10 loaders and 13 dump trucks, making the long, winding journey up from the pit bottom under load.
“We did a cycle analysis on our dump trucks,” says Kurt. “A lot of them might average 40-50 litres an hour. They’re burning 130 litres an hour of diesel going uphill, so that was also an opportunity to move forward with our overland conveying model.”
A few years ago, the price of diesel went up a dollar a litre, which cut into the margins of large diesel consumers. Kurt adds that turning to electricity will hedge against energy price jumps and cut the cost of diesel engine maintenance.
The second step was opting for a semi-portable Metso plant off the shelf, in a system customised by Mimico in Matamata.
Kurt says this high level of investment also takes in the planned second quarry on the Sutton Block over the other (north-eastern) side of the hill to the exiting pit that will be a similar size, and they didn’t want to spend a lot of money on a big, fixed plant that can’t move. Kurt says they were also inspired by an extended portable plant which he observed when he worked in the US, used by contract crushing services at sites for a limited period of time. “The equipment and chassis might only be in place for six months during a crushing campaign.”
He says they decided on a mid-range Metso equipment option from Mimico based around standard plant crushing equipment. “We went for a semi-portable plant, choosing plants off the shelf.”
That choice was Mimico’s Metso Lokotrack and Nordwheeler plant, featuring a Metso LT130E mobile Jaw Crusher with Superior Industries’ overland conveyor system feeding a modular Metso Nordwheeler portable secondary processing plant.
To have sufficient product and improve the consistency the choice was to keep the crushers, screens, and feeds consistent, rather than have three different mobile changes, says Kurt. He adds that this choice also provided a significant opportunity to move away from the diesel-powered mobile crushers.
The first uphill conveying system out of the pit had only done about eight hours of testing operations during our visit. It is located halfway down the western face and is 120 metres long, with a Metso mobile jaw crusher at the bottom end.
The plan is to keep extending this conveyor system down to the pit, crushing close to the base.
The new site has a six-megawatt capacity and accesses the local electricity network. Kurt admits other quarry sites might have an issue getting mains access.
Modular Nordwheeler setup
Garth Taylor, Mimico’s Material Processing Business Manager, led the walk-through and shared insights into the design and delivery of the processing plant, which includes a Metso Lokotrack LT130E mobile jaw crusher feeding a 120-metre-long Superior Industries overland conveyor.
This transfers material to a modular Metso Nordwheeler secondary processing plant. This mid-range portable solution balances the portability of mobile units with the performance and capacity of more permanent setups.
Garth explained that the Nordwheeler sits in the middle of Metso’s three-tiered plant offering. At one end of the scale are fully mobile, track-mounted machines that can be loaded onto a truck in the morning and be operational by afternoon. At the other end are fixed plants involving large-scale civils and infrastructure. The Nordwheeler option provides a modular approach, offering faster setup times, reduced foundation requirements, and the ability to reconfigure or relocate the plant as operational needs evolve.
Stevenson’s impressive setup uses a combination of Metso crushers and screen. The massive Lokotrack LT130E mobile jaw crusher handles the primary crushing, incorporating a C130 (1.3m wide x 1m deep) jaw crusher. Secondary crushing incorporates two GP330 cone crushers. The 315 kw cone crushers easily handle the primary feed, crushing it down further into tertiary feed or drainage products. Screening of products is handled by three CVB2060 incline screens. These screens also incorporate Metso Trellex rubber screen media to maximise wear life and reduce screen noise.
One of the Nordwheeler plant’s standout features is its quick deployment design. All components, from the crushers to the screens and conveyors, are mounted on supports that can sit directly on compacted gravel. This eliminates the need for extensive concrete foundations and means the plant can be dismantled and relocated if required. The Stevenson team initially expected a longer build timeline, but the plant was erected relatively quickly once civil works were complete.
Automation also plays a big role in the plant’s performance. The diesel-electric LT130E jaw crusher is fitted with Metso’s IC remote operating system, giving the operator full access to machine performance and operational data inside the excavator cab. Each Nordwheeler module has onboard electrical panels, and an upper-level control system allows for seamless communication between plant components.
The conveyor system
Beyond the crushers and screens, the tour also highlighted the importance of the overland conveyor system supplied by Mimico. The Superior Industries overland conveyor, designed for an operating length of 400 metres, currently operates at around 120 metres, pulling up to 750 tonnes per hour on an 11-degree incline.
The use of an overland conveyor to transport material to secondary crushing has dramatically reduced the site’s need for haul trucks and led to a significant reduction in diesel consumption.
The installation also includes 15 plant conveyors, ranging from 10 to 42 metres in length, all built by Mimico’s Kiwi engineering team. The use of truss and channel conveyor construction alongside Metso-quality conveyor components, galvanised surface treatment, and high-quality design features, such as gravity take-ups, conveyor walkways, and AS/NZS 4024-compliant guarding, speaks to the robustness and serviceability of the installation.
As Garth pointed out, the modular nature of the Nordwheeler setup means the system can be reconfigured or broken down in the future as site conditions or production goals shift. Multiple primary, secondary, and tertiary configurations are available within the Nordwheeler range, including stand-alone cones, impactors, screens, and Barmac VSI crushers, allowing quarry operators to build out the plant over time or adapt it as site requirements change.
For those of us who were part of the tour, the Stevenson Drury Quarry project stood out as a textbook example of what is possible when smart engineering is combined with hands-on collaboration.
The plant isn’t just a processing solution: it’s a strategic asset for Fulton Hogan, built to support growth, reduce operating costs, and increase operational control.