MechChem Africa September-October 2022

⎪ Heating, cooling, ventilation and air conditioning ⎪

BBE Cooling system for Venetia’s underground project Andrew Branch, director at BBE Projects, outlines BBE’s successes as it nears completion of the turnkey refrigeration and air cooling systems for the underground extension of the Venetia diamond mine

B BE Consulting’s design, supply, construct and commission contract for a turn-keyair-coolingsystemfor the Venetia Diamond Mine is cur rently approaching the final stages of its tran sition from open pit to underground mining. DeBeers’ VenetiaDiamondMinehas been South Africa’s biggest producer of diamonds since1995. Themine in theLimpopoProvince that started lifeas anopenpit operation today produces 5.5 million t/a and is set to ramp up to 5.9-million t/a with the underground expansion. Venetia is one of De Beers’ six remaining diamond mines in South Africa and the only major diamond mine to be developed in the country during the past 25 years, hence representing one of De Beers’ single biggest investments in the country. About a decade ago, the De Beers group embarked on the Venetia Underground Project, a US$2-billion project designed to transition the mine from open pit to under ground. Upon completion of this project, the mine’s lifespan will be extended by a further 23 years, ensuring that it canmaintain its cur rent level of production until 2045. The underground infrastructure compris es two vertical shaft systems for personnel transport, ore transport, routing of services, and lateral access levels. In addition, the need for coolingwas identified as part of the venti lation and occupational hygiene planning for the underground mine. BBE Consulting, a company of the BBE Group, has been involved in the Venetia UndergroundProject since thePre-Feasibility phase, so was in a unique position to deliver the air-cooling system relatively quickly – from submitting a bid to contracting for the project. BBE Group, via its BBE Projects company, submitted its first bid in 2017 in response to an enquiry document that out lined technical and process requirements for the project. Thefirst contractwas signed inApril 2018. BBE’s bidwas successful basedonpricing and its vast experience and expertise. BBEGroup isunique in themarket in thatmineventilation and cooling is its sole business. However, a major challenge proved to be the outbreak of the Covid-19 pandemic, with lockdowns and

additional health and safety protocols affect ing productivity on site and manufacturing off site, as well as the availability of parts and equipment. Despite this, work continued and the air-cooling system is currently in the final stages of being commissioned. Theair-coolingsystemconstructedbyBBE Projects includes twowater-chilling refrigera tion machines housed in a central plant that distributes chilled water to several users, as part of a distributed cooling approach. The main air cooler is a direct-contact spray chamber located adjacent to the plant build ing and will eventually feed cold air to the underground workings via a large downcast shaft, which is currently being raise-bored by a specialist contractor. BBE Projects will return to the project within the next eight to ten months to install the final duct connection between the spray chamber and the downcast shaft once the raise boring is complete. There are three subsidiary air-coolers in operation – a secondary spray chamber feed ing a satellite downcast shaft, which supplies

cold air to the development workings; and two finned-coil dry heat exchangers in the air intakes to the sinking fans, which force ventilate the production shaft. These cool air as it enters the shaft for workers currently performing shaft sinking, equipping and un derground development work. The air-cooling systemhas beenbuilt tobe extended with the addition of a third refrig erationmachine as coolingdemand increases. The plant building has a space provision, and the concrete shell for a third condenser cool ing tower was constructedwith the intention of equipping mechanicals and electricals at a later stage, as the mine develops. www.bbe.co.za

The main air cooler is a direct-contact spray chamber located adjacent to the plant building.

September-October 2022 • MechChem Africa ¦ 29