By Mark Vanderkolk, Cummins Power Generation Asia Pacific Power Systems Business director
|Cummins supplied a 14MW standby power system for a gold mine in South Africa.|
AS commodity prices weaken mine operators need to ensure their mine developments are set up to achieve sustainable cost management and enhance shareholder value. The need for a secure, efficient power supply is as important to mining operations as the equipment used by the mine to keep production up and running, sometimes on a 24/7 basis.
Many remote mines are a great distance from the nearest power grid, resulting in the need to establish reliable off-the-grid onsite power generation capability. For these locations power demand can be considerable, sometimes in excess of 50MW or equivalent to the engine power in 20 of the largest haul trucks.
While all remote mine sites off the grid require prime power generator sets, other sites on the grid may invest in generators for standby emergency back-up use during local outages. Mines not initially connected to the grid may use generators for prime power generation until transmission lines are built, after which generators can be transitioned to standby operation. Temporary power provided on a generator rental basis is another option for start-up mines and situations where a mine may require additional power capacity for a limited period.
As many sites are in harsh environments, operators can ill-afford any compromises to their equipment’s integrity. Only generators robust enough to reliably operate under extreme ambient temperatures or at high altitude are considered for applications at mining sites. For this reason, diesel engines already proven in large mining equipment are the preferred choice for onsite power generation installations as they offer proven performance. In addition, this commonality greatly simplifies the diesel engine servicing required on the site, contributing to easier and lower cost of service.
As the mining operation develops, from exploration to construction and then expansion, the power demand of the mine site also evolves. In some cases, older installed power systems may be replaced to take advantage of newer products with better fuel efficiency and lower emissions.
The power load of an off-grid mine depends on the size of the infrastructure supported, the commodity being extracted and if the mine is open pit or underground. For example, metals mining may undertake processing onsite with crushing, concentration and even smelting, accounting for a high power demand. Underground mines can consume twice the amount of electrical power per tonne of mined material compared to open pit mines. Deep mines require air conditioning, while mines in cold climates may require heating. Shafts and lifts, extractor fans, lights and dewatering pumps all require power. This equipment can demand up to 5MW of output. Operators must also consider additional power requirements for standby generators in emergencies.
Onsite power systems at mines are typically installed as a connected series of containerized generator sets with associated power control and switchgear systems. In other applications, customized enclosures are constructed to accommodate larger, open generator sets. A dedicated power station facility may even be considered if higher output generators are required, due to their larger footprint.
There is a power choice the mine can make between using a larger number of lower rated generators, or a smaller number of higher rated generators. Economies of scale can be realized by utilizing a fewer number of higher output generators to reduce the requirement for paralleling switchgear and automatic transfer switches, depending on specific power requirements.
As these installations require an integrated network, it is important that the mine operator works with a power supplier who understands their business and is able to provide a complete, plug-and-play service with global support. The nature of the industry also means projects can take place anywhere at any time - pre-integrated systems thus enable rapid set-up of power installations so energy can be made available within very short lead times.
Apart from the generator sets themselves, projects at mine sites often require peripherals like transformers, paralleling systems, switchgear, containerization or acoustic enclosures, cooling and remote monitoring. Receiving expert end-to-end guidance with power system design, application engineering, installation and commissioning is key to optimizing the specific power solution for the mine site, particularly with product service support already embedded within the mining industry.