BBE Projects, a division of consulting engineering company Bluhm Burton Engineering, was tasked with providing the cooling system for Impala Platinum’s (Implats’) No 17 shaft and turned to technology and industrial company Johnson Controls and its York YD model chillers to deliver the solution.

Platinum miner Implats is currently constructing the No 17 shaft project in Rustenberg, the second fourth-generation shaft complex on Implats’ 15-shaft Rustenberg mine. The project entails the sinking of three vertical shafts – the main, ventilation and refrigeration shafts – as well as a 43 m bulk air cooler.

“Johnson Controls is a long-standing supplier to the mining industry, and has also supplied all the recent heating, ventilation and air-conditioning (HVAC) equipment to Implats,” states BBE Projects MD Richard Gunderson.

He adds that Johnson Controls is the only company in South Africa that is able to supply the large-tonnage R134a refrigerant coolers needed for this project.

“The chillers met the extensive cooling requirements of Implats No 17 as well as the space constraints, and we believe this is the largest single machine to be installed in the southern hemisphere,” he says.

“The decision to use York chillers from Johnson Controls was [an easy one], as Implats already has 13 York plants in operation. These plants are reliable and we have experienced very few problems with them, so it made sense to standardise by using York chillers for this project and in the future,” adds Implats refrigeration engineer Andre Pieters.
The YD model chiller units supplied and installed by Johnson Controls are dual centrifugal chillers located within a single shell set.

“The YD chillers are engineered for efficiency and are highly rated in terms of energy efficiency, with shell and tube heat exchangers and open drive centri- fugal compressors. Efficient centrifugal compressors assist the chillers to adapt cooling to current requirements, improving energy use at any given time and reducing wasted cooling and wastage energy,” says Gunderson.

He adds that they are also environment friendly, using an ozone-friendly R134a refrigerant, which is nontoxic, nonflammable and noncorrosive.

He points out that the chillers are designed to supply between 14 MWR and 17 MWR, depending on the required operating conditions, and that each compressor is driven by a 1500 kW motor, while the units are controlled by a custom-built Allen Bradley programmable logic controller, which allows for greater energy savings by improving settings and controls.
“Efficient cooling is a critical component of any mining operation, as the further underground the shafts are sunk, the higher the temperature goes. However, mine cooling can be challenging, as there are often space constraints involved owing to the nature of the construction.

“The large, single-unit York YD centrifugal chillers provide sufficient cooling power, with a robust design, high operat- ing efficiency and reliability. We have customised our chillers to meet Implats’ stringent technical requirements, both mechanically and electrically,” says Johnson Controls operations manager Russell Hattingh.
He notes that combining dual compressors on a single heat exchange means that only four chillers are needed to provide the necessary cooling, instead of eight, which results in a neater configuration, a smaller footprint, lower capital costs and a more economical solution.

“Consolidating the capacity and reducing the number of pieces of equipment and ancillary equipment also mean simplified maintenance, a more cost- effective spares holding and quicker turn- around times for repairs.
“Not only does this standardisation enable us to leverage lower costs for spares and less time on training for our maintenance crew, but we also experience less downtime as a result, and eliminate the need to deal with multiple service providers. We have been able to build a relationship with Johnson Controls, which results in a more efficient service,” says Pieters.
He notes that the Johnson Controls team plays a big part in the company’s maintenance on the York plants, with yearly services carried out as needed, along with statutory pressure testing of the vessels and assistance on the occa- sional small breakdown.

“They are committed to assisting us in any way they can, whenever it is required. This kind of customer service is critical and we value the relationship,” he concludes.