Crushing circuit benefits from early contractor involvement

Boral’s Deer Park Quarry has played a vital role in the development of the city of Melbourne for more than 50 years. Basalt from the quarry in the city’s west has gone into the concrete and asphalt used on countless office towers and infrastructure projects.

{{quote-a:r-w:300-I:2-Q:“We’re achieving the product specification and the plant is performing as well, if not better than, what we’d asked for. We have consistently performed at 15 to 20 per cent above the targeted production rates.”-WHO:Luke Brown, Boral acting general manager for Southern Region Quarries}}Therefore, when the site’s 1990s vintage processing plant began to near the end of its lifespan, Boral was naturally eager to source a replacement that could be delivered efficiently without affecting output.

“Because Deer Park is in the western suburbs and close to the city, it’s well positioned to contribute to the Western Distributor and, potentially, the Melbourne Metro Rail project,” said Luke Brown, Boral’s acting general manager for Southern Region Quarries.

“Having a new plant commissioned and ramped up in time for the major projects has been one of our objectives.”

In 2015, Boral outsourced the design and supply of the new facility to Sandvik Mining and Construction. Today the plant is approaching the end of its ramp-up phase and has been completed on time and on budget with no project variations.

“We’re achieving the product specification and the plant is performing as well, if not better than, what we’d asked for,” Brown said. “We have consistently performed at 15 to 20 per cent above the targeted production rates.”

Kai Kane, project manager for the new plant, said Sandvik’s role involved designing the multi-stage processing plant and supplying processing equipment including jaw, cone and horizontal impact crushers, feeders, screens, conveyors, walkways and other infrastructure. Boral oversaw erection of the plant, with Sandvik serving as a technical consultant during the erection and ramp-up phases.

{{image3-a:r-w:300}}The processing plant comprises the following Sandvik static equipment: the CJ815 jaw crusher; the CH430, CH440, CH660 and CS660 cone crushers; the CI532 HSI impact crusher; and the SC1852, SC2462, SC3082 and SC3083 circular motion screens.

Innovative collaboration

A big driver of the project’s success is the wide range of innovative approaches by both parties. One of these was the use of an “early contractor involvement” approach, whereby Boral and Sandvik worked together to finalise the complete plan for the plant before the final supply and construction contracts were issued.

“We spent about six months achieving commercial alignment, as well as technical alignment on how to deliver the project,” Kane said.

Meanwhile, innovative 3D models showing the plant as a whole and individual stations along the production process were used in design and construction.

{{image4-a:r-w:300}}“If you look at a 3D model of a screening station, you can see the access, the height of each of the platforms, and the shape of the chutes and how this could affect blockages,” said Fabrice Bonneau, Sandvik’s project manager for the design and supply of the plant. “We were able to have a clear view of what we were designing and share this with Boral for the review of safety, maintainability and accessibility features.”

Kane said one key innovation was a more effective way of processing low quality feeds in poor weather. The deposit mined at Deer Park is olivine basalt with a significant amount of clay in between the rock layers. The old plant was unable to process poor quality deposits in bad weather, leading to Boral selectively mining the quarry and leaving tracts of the site untouched.

On Sandvik’s suggestion, Boral agreed to the use of special screens that had proven effective in Sandvik-designed processing plants operating in similar conditions in Europe. These have allowed the plant to better achieve its “mine anywhere, any time” goal.

{{image5-a:r-w:300}}“The solution that we adopted was the use of specific high capacity screens that can handle extreme clay contents,” Kane said.

“I’m confident that we can now process over 90 per cent of the time in all weather and pit conditions. I would like to say 100 per cent, but the reality is that there will always be some extreme weather conditions and combinations of clays that will prevent us from achieving that.”

Worthy ideas

Kane said close collaboration with Sandvik produced a range of other good ideas, including installation of the CI532 horizontal impact crusher.

“Meanwhile, in the overall plant, we have adopted a modular hand railing system that’s saved all site welding and allowed us to progress to site construction in a far safer manner than previously,” he said.

{{image6-a:r-w:300}}“And we have also installed two centralised dust collection units in the screening and crushing buildings, which have given us the hygiene levels that are the highest at any of Boral’s quarries.”

Bonneau said Sandvik has extensive experience designing and supplying processing plants across Europe and Africa but is a relative newcomer in this field in the Australian market. However, thanks to the early contractor involvement stage and through research, Sandvik seamlessly adapted the plant design to Australian requirements.

“The safety rules here are stricter than in Europe and we took that into account right from the beginning when designing things like the spaces between the steps and different angles required,” Bonneau said. “Once you know the rules, it’s a matter of following them and using the same process that we use anywhere in the world.”

Source: Sandvik Mining and Rock Technology

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