As Australian mining companies dig deeper and venture into more remote locations, it is more important than ever that underground operations are adequately cooled and ventilated.
Aggreko can engineer a bespoke solution to ensure this is achieved to the highest standards, even in the most searing temperatures.
This not only ensures a safer and more productive environment for workers, but also allows optimization of underground equipment.
The Australian Mining Review spoke to Aggreko’s sector manager of underground cooling, Mitch Bevan, about the services the company offers to the mining industry, and the benefits of its flexible solutions.
Modular And Scalable
Whether its chillers, cooling towers, industrial air conditions or complete turnkey solutions, all of Aggreko’s equipment is modular and containerised.
This means it can be transported easily without risk of damage to the equipment.
Like Lego blocks, it also means the equipment can be scaled up and down to get air down into the mine as needed.
The various pieces of equipment can also be used to supplement plant cooling systems as heat loads change over time.
Air Versus Water
Mining processes generate a significant amount of heat which must be expelled to avoid serious negative impacts on employees, equipment and finished products.
An effective way of monitoring and regulating temperatures at optimum levels is through utilization of chilled water plants, which can either be water-cooled or aircooled.
These are the two main installations that Aggreko offers, and both have their pros and cons, depending on a range of factors including the life of the mine, environmental and location considerations.
The modular solutions range from 50kW to 1500 kW and are used to provide supplemental, temporary or emergency cooling for high-volume applications, such as at mine sites, refineries or power stations.
Air-cooled chillers use ambient air to reduce temperatures in the condenser.
Water-cooled chillers use water via an external cooling tower to purge heat from the condenser.
Water is pumped into the tower where a fan provides a cooling effect like a giant evaporative cooler.
In either case, the chiller’s evaporator will provide chilled water to a bulk air cooling circuit, which provides the mine’s underground with chilled air. These chillers, bulk air coolers and cooling towers are generally installed in parallel to one another, to tailor a cooling solution as required by the mine’s underground.
Aggreko also provide all ancillary equipment (hose, manifolds, pumps etc.), installation, commissioning and maintenance for the duration of the project, removing a sizable responsibility from the mine, that comes along with purchase of a permanent asset.
Aggreko is the only company that hires out water cooled chillers, which are significantly more energy efficient than air-cooled chillers.
“You have got a cooling tower on the back end of the chiller that is circulating water through the chillers condenser, which has a more efficient cooling effect,” Mitch said.
“The benefit is once we piece all the equipment together and build a water cooled chiller plant, the client needs to provide about half as much power as they would with a similar capacity air cooled chiller plant.
“This reduces the client’s power requirements which is a major advantage, especially for a remote mine site, which usually runs on diesel generators.
“Transporting diesel is very expensive and also logistically challenging, reducing diesel consumption is also particularly important in current times as we are all trying to do our part to reduce emissions.”
Aggreko’s 1500KW water-cooled chiller has a unit base and frame made from heavy gauge steel, an energy efficient design and new-generation refrigerants.
Air Cooled Chillers
Aggreko also offers a full range of air-cooled chillers, which are more suitable for mine sites that don’t have an adequate water supply to feed the water-cooled chillers.
“A site, particularly if it’s in the early stages of construction, may not have the infrastructure to provide a reliable source of water,” Mitch said.
“We also can’t use poor quality water because it scales up and causes blockages and other issues, which is another reason why air cooled solutions are considered in various situations.
“With air cooled chillers, mine sites need nothing more than an interface to their ventilation system and we’ll pump air down there.”
The benefits of both systems include:
- No capital expenditure required
- Easy to calculate operating expenditure, one monthly fee
- Fast mobilisation, allowing miners to capitalise on small windows of opportunity
- Minimise risk associated with investment in permanent assets underground
- Mining can be very unpredictable long term: Aggreko’s solution includes maintenance program, reducing additional resources needed from mine
- Only pay for equipment when it is use – ideal for where peak loads exist through summer
Flexible and Modular
The inflexibility of traditional built-in cooling and mine ventilation systems means they’re not always the best option.
Aggreko’s short and long term rentals provide the ability to tailor a plant that meets the individual needs of any mine site.
A major advantage of Aggreko is its flexible solutions, for mines which do not have a clear picture of their longer-term future.
“A Mine’s ventilation system is forever changing. With various uncertainties affecting the industry, it’s hard to predict what the future holds.” Mitch said.
“If you are buying equipment, you are committing to a somewhat unknown final outcome future.
“Our main benefit is the flexibility we offer clients who only pay for the system as long they need it.”
Many mines are located in the middle of the desert or in areas with searing temperatures, where enhanced ventilation is needed in the summer.
But they only need cooling for six months of the year, and so equipment can be placed on standby during winter at a much lower cost.
For those mines, it may not make sense to have a permanent system if they are only using it for half of the year.
With rental equipment, mine sites are not liable for expenses around maintenance and upgrades.
As well as reducing overheads, Aggreko takes care of the maintenance and can provide system upgrades when new technology becomes available.
“Buying a plant not only requires initial capital but it also depreciates over time.
Furthermore, once the mine closes down the plant usually gets taken apart and has little to no salvage value” Mitch said.
“With our solutions, we charge an all0inclusive rate and that includes installation, maintenance and demobilisation when it is no longer required. Through the winter usually when the system is on standby, we do checks and ensure the plant is ready for the hot season.”
As a mine operation is closely linked to market changes, it needs to be able to scale up and down easily and efficiently.
This isn’t possible with a built-in plant, but with Aggreko’s business model, mines can quickly modify a setup at a fraction of the cost of buying permanent equipment.
As the layout of a mine constantly evolves, rental equipment provides greater flexibility for where it is located and how it is installed.
“In the early stages of a mine, the requirements of the ventilation system can change rapidly,” Mitch said.
“If they are exploring, they often don’t know where the next ore body is until they find it, so the ventilation system and layout is very unpredictable. It’s very difficult to foresee what will be required in five years.
“The advantage of a rental plant is we put our equipment in places a fixed plant would not be practical.
“For example, if the portal is the only access point, we can put our equipment somewhere near the portal and make it work.
“We can put our equipment near temporary shafts and move it to a different location as the air flow requirements change.”
CSA Mine is an underground copper mine located in Cobar in central western NSW.
As the mine deepened and expanded, the need for enhanced cooling and ventilation increased.
As the leaders of underground mine cooling in Australia, Aggreko’s expert team were able to engineer a unique 12MW thermal package, utilising a range of specialised cooling equipment from fluid chillers and cooling towers to diesel generators.
Aggreko engineered a bespoke cooling solution that delivered 180m3 of air per second into the mine at just eight degrees Celsius.
When air quality is poor and the temperature is too hot, equipment can overheat and miners’ health can be put at risk.
With Aggreko’s equipment in place, the underground mine environment was not only safer after the air quality and ventilation was drastically improved.
Decreasing the temperature also meant both workers and equipment were able to operate longer with increased efficiency.
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