October 1, 2022
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BBE Projects approaches delivery of Venetia underground cooling system

By on August 10, 2022 0

Project delivery company BBE Projects is about to complete the delivery of a turnkey air cooling system for diamond miner De Beer’s Venetia diamond mine in Limpopo, which is currently nearing the final stages of its transition from open pit to underground mining.

BBE Group, of which BBE Projects is a subsidiary, was contracted to design, supply, build and commission the system after being involved in the Venetia underground project from the pre-feasibility phase, engaging with the master’s team from this early stage to help plan the transition from open pit to underground mining.

About a decade ago, the De Beers Group embarked on the Venetia Underground Project, a $2 billion project designed to convert the mine from an open pit to an underground mine. At the end of this project, the life of the mine will be extended by 23 years, which will allow it to maintain its current level of production until 2045.

The underground infrastructure includes two vertical shaft systems for personnel transport, ore transport, service delivery, lateral access levels at levels 54, 94, 100 and 103 and bottoms of the shaft at level 107 .

The need for cooling was identified as part of the ventilation and occupational hygiene planning for the underground mine.

To develop an adequate cooling and ventilation system, the mine needed to engage the services of specialized and experienced consulting engineers who focus on mine ventilation, refrigeration and cooling.

Thanks to its involvement throughout the project, BBE Group was able to deliver the air cooling system relatively quickly, from bidding to contracting the project. BBE Projects submitted its first bid in 2017 in response to a survey document that outlined the technical and process requirements for the project.

The first contract was signed in April 2018 after BBE’s successful bid based on price, as well as its vast experience and expertise.

BBE Group claims to be unique in the market in that mine ventilation and cooling is its only business. However, a major challenge proved to be the Covid-19 pandemic, with additional health and safety lockdowns and protocols affecting onsite productivity and offsite manufacturing, as well as parts and equipment availability.

SYSTEM

The air-cooled system built by BBE Projects comprises two water-cooled refrigeration machines housed in a central facility that distributes chilled water to multiple users, in a distributed cooling approach.

The main air cooler is a direct contact spray chamber located next to the plant building and will eventually supply cold air to the underground workings via a large sunken shaft, which is currently being drilled by a specialist contractor.

BBE Projects will return to the project in the next eight to ten months to install the final conduit connection piece between the spray chamber and the sunken well once the raiseboring is complete.

Three subsidiary air coolers are in operation – a secondary spray chamber feeding a sunken satellite shaft, which supplies cool air to the development workings; and two finned coil dry heat exchangers in the downcomer fan air inlets, which forcefully ventilate the production well.

These cool the air as it enters the shaft for workers currently performing underground sinking, equipment and development work.

The air cooling system was built to be expanded with the addition of a third refrigeration machine as cooling demand increases.

The factory building has space and the concrete shell of a third condenser cooling tower under construction with the aim of fitting out mechanical and electrical equipment at a later stage, as and as the mine develops.

The Venetia mine has been South Africa’s largest diamond producer since 1995.

Currently, the mine produces 5.5 million tonnes of ore per year and will reach 5.9 million tonnes of ore per year once the underground operation reaches a steady state of production.

The mine was opened in 1992 by the former chairman of De Beers Harry Oppenheimer.

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