Energy efficiency and emissions reduction in mining

Targeting emissions: cleaner pyroprocessing

Alongside energy efficiency, reducing direct carbon emissions is a primary concern for pyrometallurgical processes. For example, the redesigned gas suspension calciner from FLS reduces fuel consumption by 5%, power consumption by 8%, and CO2 emissions by 7%. In lithium production, the FLS Pyro Island aims to deliver maximum efficiency in spodumene conversion. Among other design innovations, it includes the FLS indirect cooler, which recovers a significant portion of the sensible heat in the hot beta spodumene – lowering specific fuel consumption and the associated carbon footprint by up to 30% compared to other cooler designs. In addition, we have options to use alternative fuels, including green electricity, biofuels, and hydrogen, as primary energy sources to replace fossil fuels.

In the processing plant: comminution

Comminution is the first step when the ore arrives at the processing plant: it is also the largest electricity consumer in the mine – with the mill accounting for much of this. Optimising the mill feed, thus, significantly benefits milling efficiency. For example, the Eccentric Roll Crusher (ERC®) can reduce specific power consumption by 40% compared to a gyratory/jaw crusher in the same application while offering a higher reduction ratio, wider CSS range, and more fines in the product. The resulting mill feed is finer and more uniform, improving grinding efficiency.

Meanwhile, coarse particle flotation increases the particle size at which acceptable flotation is possible. This enables the mill to operate at a coarser grind, which results in significant energy savings per tonne of ROM material processed. The coarseAIR™ Flotation Cell captures particles up to 850µm in sulphide and >1mm in industrial minerals. It is ideal for rougher applications to process a coarse ball mill product. It can also reprocess tailings streams to scavenge valuable coarse particles lost in conventional flotation processes. In some cases, it has been shown to recover more than 60% of the target mineral that would otherwise have been lost to rougher and scavenger tailings.

Regarding the mill itself, SAG mills retain a dominant position as the workhorses of the mineral processing plant. In these mills’ dynamic operating conditions, the speed at which operators can adjust to changes in feed rate, mill speed, and slurry density has a critical impact on mill efficiency. Digital optimisation solutions have a key role to play here. For example, LoadIQ mill scanning technology measures and predicts mill behaviour according to ore properties, trajectory (liner wear), and other main process variables. The smart sensors ensure regular and accurate adjustments to mill loading that increase throughput while reducing energy use.