After many years of belt tightening, miners are gearing up again for expansion projects with costs for labour, equipment, and fuel on the rise. Rising costs, together with eroding metal prices due to ongoing trade disputes, have caused margins to come under pressure recently, so it's important to look for further opportunities to drive down costs, both short-term and long-term.
While automation is much talked about in the industry, savings from energy efficiency are often overlooked and can rapidly deliver savings.
For existing operations, the most powerful tool is to track energy cost per tonne and consider energy efficiency when choosing where to spend sustaining capital. For new projects, criteria on energy efficiency should be established early, and built into the broader investment decision and new mine design, as this is a significant lever to lower overall operating cost (particularly for off grid and underground operations). In addition, genuine focus on energy efficiency with proper media communication, helps communicate social responsibility for the environment and may assist in maintaining the miner’s long-term license.
While energy efficiency is often thought of in terms of ‘switching off the lights,’ there are many meaningful opportunities to reduce power consumption that are often unrealised. For starters, understanding the energy cost per tonne or usage per tonne helps operations focus on where efficiencies are lost and productivity is compromised.
For example, fuel burn is a big driver in the mobile fleet with big variances arising from pit layout, road conditions and driver behaviour. Many of our clients directly monitor and manage roll-resistance and design ramps with a constant gradient, yet underestimate ‘simple’ measures like tightly controlling fill factors, reducing queuing times or training truck drivers to drive both safely and economically. Calculating the savings in terms of energy cost per tonne from these initiatives provides a valuable lens into a well-run operation.
Energy efficiency considerations also help to prioritise, particularly when making investment decisions and looking at the total energy life-cycle cost. Does it make sense to spend the money on the more powerful grader? Should we design a full load-out ramp at each level? What are the benefits from ventilation on demand and other automation? Is there opportunity to reduce energy needs by leveraging battery operated equipment?
Mines are built around existing machinery and as soon as machines are changed, mine design can be modified. This is particularly relevant in underground operations, where tunnel sizes are dictated by machine dimensions and ventilation requirements. There is a significant opportunity to completely rethink the mine design and mining methods by leveraging state of the art mining technologies.
For example, a diesel scoop tram issues emissions and heats the local environment by 15-20 degrees Celsius, whereas a battery-powered tram only adds 3-5 degrees to the local environment. The battery-powered scoop tram is not only better for a safe, low emissions environment, but has much higher energy efficiency, with longer-term energy cost savings often between 25 and 50%.
In underground operations, electric equipment (either wired, battery-powered or trolley-assisted) can safely reduce ventilation requirements, as well as the number of required ventilation tubes. As a result, tunnels can be much smaller, reducing mine waste and gaining precious time and schedule through increased advance rates, improving the overall return on investment.
This also reduces capital expenditure in new mines, as less ventilation capacity needs to be built. This investment can benefit existing mines, as extra available ventilation capacity can be used to drive an additional drift or mine another level, while also making the mine safer for the workers by reducing emissions.
While innovative equipment and usage monitoring can deliver enormous value, the future of mining does not stop with machinery and measurement. There are many energy efficiency opportunities that can deliver extensive long-term value when switching energy sources, ranging from total mine electrification (including hoists or other bulk transport systems) to regenerative energy systems for the tailings management facility, optimising trade-offs between blasting versus crushing versus milling for the most energy efficient concentrator designs, and remote distributed power, to name a few.
Ultimately, energy efficiency provides an additional metric to guide teams, projects and operations in making the right decisions and trade-offs to capture maximum value from both developing and operating mines.