A new quarry in the Northern Cape set to be an important source of limestone for a local cement plant, will require significant infrastructure to enable access to the deposit.

The deposit is said to have the potential to provide a 40-year supply, delivering about two-million tons of limestone a year to AfriSam’s Ulco integrated cement plant.

The R31 road between Kimberley and Postmasburg will be diverted to accommodate the high volumes of large ore trucks and abnormal load mining equipment that it carries, while extensive excavation and civil engineering work is undertaken to construct a tunnel underpass system.

“In compliance with the road authority’s requirements, the tunnels will traverse the full 32 m width of the road reserve – to allow for future road widening, in addition to the pipeline servitude,” says AfriSam manager: Saldanha and strategic projects Gavin Venter. “The two tunnels themselves will be over 50 m in length, and will be separated to enhance safety as there will be counterflow traffic to and from the plant.”

The 5-m-high by 5-m-wide tunnels will be excavated to 12 m below the R31 road level, and constructed as large culverts with steel reinforced in-situ cast concrete. The design work ensured a tunnel alignment to suit the future possibility of an in-pit crusher and conveyer belt which could provide an alternative method to feed crushed material to the existing pre-blending stockpiles.

The civils works also has to accommodate the 700-mm-diameter Gamagara pipeline, supplying the Northern Cape with water from the Vaal river. To avoid the risk of disrupting this water supply, a concrete bridge has been constructed parallel to the existing pipeline, inside which a new 100 m stretch of pipeline was laid.

AfriSam says the supply of readymix, which will include the company’s cement, will come from Kimberley, about 80 km south. With ambient daytime temperatures that can rise to 40 0C, this will require careful use of admixtures to achieve the required slump by the time readymix trucks arrive on site.