The South African National Roads Agency’s R637-million R23 rehabilitation project, from Standerton to Greylingstad, in Mpumalanga, is due for completion by the end of 2015.
South African crushing specialist Danoher Contracting is subcontracted to JSE-listed construction and engineering group Basil Read’s subsidiary, Roadcrete Africa, for the project and has a 24-month, R40-million crushing contract to supply the project with two-million tons of road-base material.
According to Danoher director of operations Royden Webster, 50% of crushed rock has already been supplied and he predicts that the company will have completed supply to the project in the next three months.
The R23 rehabilitation project involves road reconstruction and additional pavement layers and passing lanes.
The total distance of the road rehabilitation project is 52 km. The existing road is a two-lane, single-carriageway road, with gravel shoulders on either side. The lane widths are generally 3.6 m to 3.7 m, while the gravel shoulders are generally about 2.5 m wide.
Webster notes that Danoher has an 8 ha quarry that runs 24 hours a day to crush the material for the project and also undertakes its own drilling and blasting of the dolerite rock.
Danoher has acquired equipment for the quarry from mining equipment supplier and original-equipment manufacturer Pilot Crushtec International, which includes equipment from construction equipment and services provider Sandvik Construction.
Dolerite material is crushed and screened to add a consistent 82 000 t/m of rock to Roadcrete Africa’s stockpiles for the project.
The production cycle begins with the loading of blasted material into the Sandvik UJ440 jaw crusher, which is then fed into a Sandvik US440i cone crusher. The crushed rock is then loaded into a Sandvik QA451 mobile triple-deck screen, with the –40 mm crushed rock being fed to Pilot Crushtec’s locally produced TwisterTrac VS350E tracked vertical shaft impact crusher to increase the fines and super fines content and the +40 mm rock is fed to a UH440i for tertiary crushing.
As a result of the supply, Danoher is assisting Pilot Crushtec in the ongoing development of its new TwisterTrac.
“This has yielded significant performance gains in key areas like fuel consumption, which has been reduced to 65 ℓ/h while processing up to 400 t/h. Our goal is based on the most tons we can produce in a year. By using high output machinery, like the new Sandvik heavy-duty crushers and screens, our projects become viable because we can deliver product at a rate in excess of 350 t/h,” Royden notes.