Writer: Kim Cloete
Mobile units which cool the air in remote underground areas like mines are helping to provide a more comfortable working environment for workers who don’t have access to chilled water for cooling.
M-Tech Industrial programme manager, Dr Martin van Eldik, says the Enerflow units are unique in that they can be transported on tracks to areas where they are needed.
“As the mine gets deeper and deeper, you move further away from your source of cooling. With mobile units, we are able to move them to where people need cooling,” says van Eldik.
The Enerflow ACU MkI (100kW nominal cooling) fits into a standard mine cage and can be easily moved as mining activities expand. The larger ACU MkII (250kW nominal cooling) was developed to be slung under the cage.
“The ACUs maintain a typical wet bulb temperature of between 26 degrees Celsius and 28 degrees Celsius in areas where cooling capacity is inadequate, inefficient or where additional cooling is required. The Enerflow ACU is particularly well suited to remote underground areas where temperatures approach the critical 32.5 degree Celsius wet bulb limit,” says van Eldik.
Wet bulb temperature is the lowest temperature that can be reached under ambient conditions by the evaporation of water only, and is the temperature you feel when the skin is wet and exposed to moving air. When the ambient temperature is too high, underground workers are in danger of fatal hyperthermia caused by heat stress.
“By law, if your wet bulb goes above 32.5 degrees, you need to get your workers out of the section,” says van Eldik.
To combat the excessive temperatures, the Enerflow ACU draws in hot air, and cycles it through the air evaporator equipped with a standard mine ventilation fan to cool it, before feeding the cooled air back into the working environment.
Van Eldik says he sees an increasing need for mobile cooling units as mines expand and the rock temperature gets warmer in particularly deep areas.
“It’s important that we make it as comfortable as possible for people to do their work underground. Proper ventilation is vital.”
Van Eldik says the units use a lot less water than the big refrigeration plants which are generally used in mines. The Enerflow units are also environmentally friendly, as much less water needs to be pumped out of the mines and cleaned and conditioned.
The ACUs are being used mostly in gold mines in South Africa, including Goldfields’ Beatrix mine in the Free State. Van Eldik says he sees great potential for expansion into other African countries, including Zambia.
“Depending on the country, the regulations and the mine, we look at how we need to adapt the unit. There may be regulations for copper mines that we need to look at. We can change and upgrade the units and are constantly doing research on this.”
He says keen interest has been shown in the units from Canada, Asia, Australia and South America.
The Enerflow underground air cooling unit (ACU) technology has been developed by M-Tech Industrial in South Africa, and marketed by Mine Support Products (MSP).
Vereeniging-based MSP is jointly owned by international manufacturing and engineering company, DCD Group and Robor, which manufactures and supplies welded steel tube and pipe, cold formed steel profiles and associated products.