According to the Weir Group, studies and on-site data show that HPGRs can lower direct energy consumption as well as through downstream energy savings they create in grinding and mineral recovery.

An independent report released in May spotlights the global mining industry’s energy usage, illuminating where energy is consumed and linking it with opportunities and pathways to decarbonize.

The report, commissioned by the Weir Group, analyzes mine energy use from more than 40 published studies, centered on five commodities — copper, gold, iron ore, nickel and lithium. For these five metals, it finds that comminution alone accounts for 25% of final energy consumption at an average mine site. Extended across all hard rock mining, this is equivalent to up to 1% of total final energy consumption globally.

The report reconfirms comminution as a key target for energy and emissions reduction efforts. These findings align with the mission of the Coalition for Energy Efficient Comminution (CEEC), a global initiative to accelerate eco-efficient minerals, with a focus on energy-efficient comminution. It follows previous CEEC statements indicating up to 3% of global electrical energy is used in comminution when considering all mined commodities, quarrying and cement production.

Among the observations contained in the report is recognition that small improvements in comminution circuits can lead to relatively large savings in both energy consumption and GHG emissions. The report stated: “Optimization opportunities in existing crushing and grinding circuits can include grinding surveys and analysis to ensure optimum grind size is being maintained, ball charge is optimized, and recirculation is minimized. This generally involves sampling and analysis of slurry at various points in the comminution circuit and applying simulation techniques and potentially laboratory analysis to ensure the grinding circuit and downstream processing like flotation or leaching are optimized. Replacing the existing crushers and (traditional) mills with highly effective comminution equipment can mitigate or reduce the grinding media requirement, which will reduce the CO2 emissions significantly.”

According to the report, another opportunity in comminution optimization is with the use of advanced process control for grinding circuits. Process control algorithms can be set to maximize automated control of process plant and maintain operations within specific envelopes. This sort of control will minimize operator intervention and keep critical parameters in grinding circuits within optimum ranges. Advances in sensor technology, and reduction in the costs of sensors, means the business case for advanced process control is more attractive now than in prior years.

In addition to optimizing comminution, the report highlights other energy and emissions reduction opportunities such as the redesign of grinding circuits at greenfield sites, improved drill and blast approaches, preconcentration, and the use of AI and machine learning to improve decision making.

The report accentuates the mining industry’s role in supporting the transition to net zero emissions, needed to limit global temperatures in line with the Paris Agreement. This includes more efficient and sustainable technologies if the industry is to meet the challenge of decarbonization, noting that small improvements in existing mines can lead to large savings in both energy consumption and greenhouse gas (GHG) emissions.

According to report author Marc Allen, a 5% incremental improvement in energy efficiency across comminution could result in GHG emission reductions of more than 30 million metric tons of CO2e.  “A relatively modest 5% improvement in comminution, across the industry, may result in emissions reductions close to the total emissions for New Zealand (35 million mt CO2e). A more robust energy audit process and implementation of low-cost opportunities across a mine and process plant may result in total energy savings of up to 10%-15% and overall emissions reductions of more than 200 million mt of CO2e/a, depending on the source of electricity. Large-scale introduction of renewable energy provides the potential to reduce emissions significantly in the industry — hundreds of millions of tons of GHG savings when there is widespread adoption of renewable energy and energy storage.”

CEEC CEO Alison Keogh cited three key collaboration actions vital to success: sharing best practices, to ensure existing mines and processing plants are better informed and take actions earlier to become more energy and water efficient; sharing new technologies, designs and innovations; and supporting testwork and pilots of novel technology on sites and at increasing scales.