AfriSam’s Pietermaritzburg Quarry (PMB Quarry) provides a diverse portfolio of aggregate products that are suitable for readymix, asphalt, civils, road building and concrete product manufacturing in the construction sector. The operation’s material output is currently vital to key infrastructural improvements in the area which include the upgrades to the N3, municipal roads, and various building projects. Construction World <<i>> visited the facility to learn about upgrades that will lead to optimised operations and the ability to step up production when the construction industry fully recovers.
AfriSam in KwaZulu-Natal
AfriSam is a supplier of superior quality construction materials and technical solutions optimising the use of cement, aggregate and readymix concrete. For AfriSam, the aggregate and readymix markets in KwaZulu-Natal have done well from a volume perspective considering the volatility over the last three years. In addition to the infrastructural national and municipal road projects that the PMB Quarry supplies with base and sub-base material, it has supplied readymix and other products to the Midlands Mall upgrade, the Brookside Mall and Southgate complex developments, housing in surrounding rural areas, the Durban University of Technology with its related student housing and various bridge projects.
Benefitting the community
“It is important for us as AfriSam to invest in the development of communities surrounding our operations,” says Ernest Sebeelo, Works Manager at AfriSam’s PMB quarry. As such the PMB Quarry has contributed to education by establishing a school, provided the community with a computer and science laboratory, and is in the municipal approval stage to develop a library in partnership with the municipality and its external funders. The quarry also provides opportunities to people from the informal settlement to its southwest. This includes the removal of alien plants, site cleaning and some security,” says Sebeelo.
Quarrying in a fast developing area
The AfriSam supply channel in KwaZulu-Natal is divided into two areas: coastal around Durban, and the Midlands (where the PMB Quarry is located).
The PMB Quarry is in the Msunduzi local municipality, located to the northeast of the city. Established in 1946, the quarry has a Life of Mine of 100 years and provides employment to 27 direct employees and up to 60 indirect contractors.
“The urban area surrounding the facility is growing rapidly with various developments already completed or in the pipeline. The greater Pietermaritzburg area also has a lot or work in the pipeline,” says Sebeelo.
“Our facility aims to provide projects within a radius of 60 km. However, our road stone is of such a good quality that this has, at times, increased to 100 km. We have, for instance, supplied road stone for the construction of the King Shaka International Airport,” says Sebeelo.
Built for efficiency
Sampie Kruth, AfriSam’s Engineering Manager for KwaZulu-Natal explains that AfriSam’s PMB facility has a plant A and B. “The A plant produces aggregate and sand and is split in two sections, namely primary and secondary. The primary plant produces crushed material for the intermediate stockpile (ISP), which is where the secondary plant receives its first crush material. It further produces products that only go through the jaw crusher (first crush) and also hand stone (rock that is used for gabion baskets).
“AfriSam’s latest upgrade to the plant is a Metso C120 jaw crusher at the primary feeder,” Kruth says. This crusher feeds the secondary 57H Osborn cone crusher from where the material goes to the ISP. “We have three Metso HP200 crushers, and a vertical shaft impact crusher which was upgraded 18 months ago.”
The secondary plant that feeds from the ISP produces coarse aggregates (28, 20, 14 and 10 mm), road stone washed aggregates and crusher dust that is used for asphalting, concrete and various other applications in the civil engineering and building industries.
The B plant is much smaller and is a conventional base material plant. It currently produces G2, G5 and sub-base material. “It has a 30x42 Telsmith jaw crusher from where material moves through a 48 inch Telsmith cone crusher. The oversized material gets sent back to a 36 inch Telsmith cone crusher for recrushing. The G5 is deposited onto a stockpile while G2 material goes through a vertical shaft impact crusher and then to the stockpile,” Kruth explains.
Increasing production
In general, the quarry has had significant capex investment to ensure we are ready when the market fully recovers. After AfriSam’s Coedmore quarry, this quarry produces the second largest volumes in KwaZulu-Natal,” Kruth explains.
At the start of 2021, PMB Quarry installed a VSI crusher in its tertiary plant. “This Techroq T8R VSI crusher is an impact crusher and makes use of velocity and inter-particle impact to shape the material, thereby reducing the flakiness index of the material. The reason behind this is to improve the quality of the aggregate required for road stone and asphalt,” Kruth explains. This crusher was installed mainly to increase sand production at the plant to keep up with market demand. This project increased the sand output by approximately 15% of overall production.
An upgrade for consistency
The second and most recent upgrade was done during the industry builder’s break at the end of 2021. “The purpose of this upgrade was to replace the existing crusher with a Metso C120 jaw crusher,” says Kruth. “We had numerous issues with the steel and concrete support base of the previous crusher due to the dynamic forces of the crusher during operation. This resulted in fatigue cracks on the crusher main frame which had to be welded every few months,” says Kruth.
The new Metso C120 crusher is mounted on rubber dampers. “The dampers reduce the dynamic forces from the crusher onto the support steelwork – almost like shock absorbers,” says Kruth. The crusher is not bolted to the frame and keeper plates are used to keep it in position.
The benefits of the upgrades
The crusher has been in operation for three months and benefits such as reduced downtime and increased safety are already evident. “The new jaw crusher has hydraulic gap adjustment which negates the need to physically adjust gaps. In addition, it is more maintenance friendly.”
From a safety perspective, it is safer to lift the crusher liners with an overhead crane as it has casted lifting holes instead of lugs, and special OEM supplied lifting tools.
“Operationally we are now optimised for success,” says Kruth. “We have reduced the dynamics on the civils, minimised downtime and improved safety and sustainability,” concludes Kruth.
