The initiative, which saw the replacement of major components and a switch to the use of an ozone friendly refrigerant, has improved performance of the chillers significantly.
This has increased energy efficiencies and assisted the mine to reliably reach the needed cooling capacity, which has delivered improved working conditions and increased productivity.
Harmony is one of the world’s leading gold mining companies with operations throughout South Africa and Papa New Guinea.
Tshepong is one of Harmony’s largest operations, it has a single vertical shaft extending to a depth of 2 161 metres.
The mine undertakes conventional undercut mining, where ore is transported to the Harmony 1 plant, 23 kilometres away. The mine employs approximately 5,000 people.
The three chillers at the Tshepong surface plant deliver 10.2MW of cooling each, supplying 300 litres per second of water at three degrees Celsius to cool the underground workings of the shaft.
Tom Smith, Chief Operating Officer at Harmony Gold South Africa said:, “Our 25-year old chillers were nearing end of life and we faced a number of challenges.
“The equipment was not functioning efficiently, parts were hard to get, and we were experiencing a lot of breakdowns. With insufficient cooling in the mine, working conditions are not optimal, affecting workers’ outputs and impacting production schedules.”
Johnson Controls proposed overhauling the existing chillers, stripping out the failing components and replacing them with newer technology that would improve performance and help the mining operation achieve specified cooling requirements.
As the chillers were running on refrigerant R22, and a hydro chlorofluorocarbon (HCFC) refrigerant that is in the process of being phased out due to its ozone depletion potential, Johnson Controls also proposed the use of the more eco-friendly R134a refrigerant.
Neil Cameron, General Manager of Johnson Controls Building Efficiency Africa said: “It was imperative that the mine not only get the needed cooling capacity, but that the solution selected be reliable and well supported to minimise risk going forward.
“With a well-established presence in South Africa, a good track record in the mining industry, experienced and highly skilled resources, and proven solutions, Johnson Controls’ proposal to retrofit the chillers with York equipment was selected.”
Smith concluded: “We are very pleased with the outcome. The Johnson Controls team is highly skilled and experienced and delivered the project to specification. The retrofit has improved cooling performance measurably – and it has made a major difference to the teams working underground, improving working conditions and productivity.