Cogeneration projects a viable option for mines

22nd February 2019 By: Khutso Maphatsoe - journalist

Having completed a cogeneration project with diversified miner Anglo American Platinum (Amplats), energy solutions provider Vuselela Energy director Jacques Malan says the company looks forward to working on similar projects for more mining companies.

Cogeneration, in the context of the South African mining industry, entails the use of wasted process energy for usable heat and/or power generation. Numerous examples exist at smelting operations where hot off-gas, or sometimes combustible off-gas is released into the atmosphere. These sources can relatively easily be harnessed for power generation.

“The cogeneration space is very interesting for engineering-driven companies such as Vuselela. We are technology agnostic and there are so many different types of technologies for different applications that we are always looking for new opportunities,” says Malan.

Vuselela Energy installed an organic rankine cycle (ORC) in 2015 at Amplats’ Waterval smelter in Rustenburg, in the North West.

In the ORC, the waste heat from the smelter’s high temperature cooling circuit is used to boil an organic liquid; the resulting vapour drives a turbine, which, in turn, drives a generator, and the generator produces electricity. It is a closed-loop system with zero blow-down or atmospheric release making it much more environment-friendly than a steam system.

Apart from long-term operation and maintenance, the company is currently implementing major upgrades to the heat exchangers to improve reliability.

Anglo American benefits from the Thermal Harvesting project in that it has access to less expensive electricity over a 15-year period and a lower carbon footprint.

“We, are planning to build more of these types of cogeneration plants, owing to our understanding of the technology and the points of application in industry. We are hoping to complete projects for the mining companies with chrome and manganese operations using a range of applicable technologies,” Malan points out.

He explains that the reason the company is targeting chrome and manganese mines is because the mines are energy-intensive users, with some having electricity requirements and carbon footprints similar to small cities.

Malan mentions that the company is also considering the installation of solar plants of about 10 MW at mine sites as an alternative power source, on a similar build-own-operate-transfer basis to their cogeneration offering.