In a concentrator, the power bill is mostly a grinding bill. The SAG and ball mills turn day and night and use more electricity than everything else in the plant put together, so a small drift in how they are loaded, fed or classified is a large number by month end. Yet most sites still watch one figure: the utility meter. iFactory's Equipment Submetering puts a live kWh-per-tonne reading on each mill, pump and circuit, checked against the ore being treated, so the team can see which machine is costing more today and why. To see it on your own plant data, book an energy review.
Mineral Processing Energy Monitoring: kWh per Tonne, Mill by Mill
Submeter the SAG mill, ball mills, pumps and flotation. See energy per tonne live, checked against ore hardness, and find the kilowatt-hours that buy no extra grind.
- A live kWh/t figure for every major machine
- Compared against the ore, not just the clock
- Losses ranked in kWh/t and in money
- Grinding is where most of a concentrator's electricity goes.
- One utility meter shows the bill, not the cause. Submeters show the machine.
- kWh per tonne only means something once it is checked against the ore.
Where a Concentrator's Power Goes
Follow the kilowatt-hours and they lead to two kinds of machine: the SAG mill and the ball mills.
Everything else — crushers, conveyors, flotation cells, thickeners — shares what is left. That is why an energy programme that starts anywhere but grinding starts in the wrong place. Our support team can help you sketch the same split for your plant.
The published numbers agree. A survey of Australian copper and gold mines found comminution used 52% of site electricity. A later review of 40 studies put it at 30–40% of all energy at copper mines, diesel included.
Illustrative plant. Tariff and tonnage are assumptions; use your own.
Breaking rock is hard work
Only a small part of a mill's energy ends up as new, finer particles. Most leaves as heat and noise. Small gains matter because the base is so large.
A mill draws power either way
A turning mill pulls close to full power whether the feed is rich, poor, fast or slow. When tonnes dip, kWh per tonne climbs straight away.
The ore is getting harder
Grades are falling, so more rock is ground for the same metal. Chile's copper agency expects mine power demand to grow faster than output.
Each kilowatt-hour saved in grinding is also an emission avoided. One industry report estimates that a 5% efficiency gain across comminution would cut emissions by as much as New Zealand produces in a year.
One Utility Meter Cannot Tell You This
The site meter gives you the bill. It cannot tell you which machine ran it up.
Submetering splits one big number into the pieces that people can act on. Each level down answers a sharper question — which area, which circuit, which machine. Most plants already hold more of this data than they think. To map the meters you already have, book a working session.
Illustrative day at 40,000 tonnes. Two ball mills on the same duty, 0.2 kWh/t apart: only the third level shows that.
By machine
The mill, the pump or the blower — not just "the grinding area".
By tonne
Power matched to the weightometer, so the figure is kWh/t, not just kW.
By hour
The bad three hours stand out, instead of vanishing into a daily average.
What to meter first
The mills
SAG and ball mill motors are the biggest loads, and the drive usually measures them already.
The pumps
Cyclone feed and tailings pumps. Published energy curves put cyclone feed pumping near 1.6 kWh/t on average.
The air
Flotation blowers and compressors run all day and drift quietly.
The long tail
Conveyors, thickeners and lighting can share one feeder meter to start with.
kWh per Tonne, Done Properly
A raw kWh/t figure blames the plant for the ore. A fair one compares each hour with what that ore should take.
Hard ore takes more energy to grind. That is geology, not waste. So iFactory sets an expected figure for each ore blend from your own best running, and reports the gap. Ask our process specialists how the expected values are set.
Illustrative. Notice the mill power barely moves; the tonnes do. On raw kWh/t the hard ore simply looks bad. Against its own expected figure, it is where the real gap is.
Why this matters: without the ore check, a week on hard ore looks like a bad week, and a week on soft ore hides real waste. People stop trusting the figure. With it, a gap means something the plant can fix.
- Wet tonnes. Use dry tonnes, or moisture swings will look like energy swings.
- Clocks out of step. The power meter and the weightometer must share one time base.
- Daily averages. A day can look fine while three hours inside it were poor.
What 1 kWh per Tonne Is Worth
A 4% improvement sounds small. On a plant this size it is a seven-figure line every year — and it comes from running the same equipment more steadily, not from buying new mills.
Five Places the Kilowatt-Hours Hide
Most wasted grinding energy is not a fault. It is a mill running a little outside its best window, hour after hour.
Each of these shows up clearly once the machine has its own meter and its own kWh/t trend. Together they add up to the full 1 kWh/t in the worked example above.
None of it needs new equipment. It needs the kWh/t trend in front of the operator at the moment the mill leaves its window. To rank the five on your own circuit, book a loss review.
Too empty, and steel hits liner instead of rock. Too full, and the charge stops tumbling well. The window is found from your own mill's data.
These levers are well documented. In published case studies, a change to SAG mill pulp lifters cut specific energy by about 10%, and better blast fragmentation lifted mill throughput by 5 to 20%.
From Meter to Decision
The readings matter only if they reach the person who can act, in time to act.
Much of the metering is often there already: mill drives, motor protection relays and switchgear usually measure power. iFactory reads those, fills the gaps with added meters where needed, and joins power to tonnes and ore type minute by minute. Our integration team can check what your plant already measures.
Meter
Power is read from each mill, pump group, blower and feeder.
Match
Each reading is tied to tonnes from the weightometer and to the ore blend.
Compare
Live kWh/t is set against the expected figure for that ore.
Rank
Gaps are listed by machine, in kWh/t and in money, with the likely cause.
The morning meeting, before
- The power bill arrives next month.
- Energy per tonne is one figure for the whole plant.
- A poor shift is put down to hard ore.
- Nobody can say which mill or pump drifted.
The morning meeting, after
- Yesterday's kWh/t is on the screen, by shift.
- Each mill and pump group has its own figure.
- Hard ore is allowed for; the gap that remains is real.
- The machine, the hours and the cost are listed.
Who sees what
- Control room operator. Live kWh/t beside the mill load and feed rate.
- Mill superintendent. Yesterday's gaps by shift and by machine, each morning.
- Energy manager. Monthly kWh/t by circuit against target, ready for reporting.
- Maintenance planner. Energy drift that points to liners, pumps or classifiers.
- Sustainability lead. Energy and emissions per tonne by circuit, ready for the annual report.
iFactory monitors and recommends. Your control system and your operators stay in charge of the mill.
Turnkey AI: Delivered, Connected and Live in 6–12 Weeks
You do not build this. It arrives ready.
iFactory ships as a pre-configured NVIDIA AI server, racked and ready, with the software pre-loaded. Rack it, plug in power and Ethernet, and the AI is live on your network.
Our team handles cabling, network setup, PLC and SCADA integration, operator training and 24×7 remote monitoring. The server sits inside your own network, and your plant data stays on it. For a scope matched to your concentrator, request a turnkey quote.
Ship, network and data
Server installed. Existing power meters, drives and weightometers connected. Meter gaps listed and filled.
Model training and pilot
Expected kWh/t learned for each ore blend from your history. Grinding circuit monitored in shadow and checked with your metallurgists.
Go-live and training
Live screens for the control room, superintendents and the energy manager. Training by role. 24×7 remote monitoring begins.
Frequently Asked Questions
How much of a mine's energy goes to grinding?
It depends on what you count. In a survey of Australian copper and gold mines, comminution used 52% of site electricity and about 36% of all site energy once diesel was included. A review of 40 studies put copper mines at 30–40% of total energy.
What is a good kWh per tonne for a SAG or ball mill?
There is no single good number. It depends on ore hardness, feed size and how fine you grind. The fair test is your own best running on the same ore. Industry energy curves can then show how your circuit sits against other mines.
Do we need to install new meters?
Often fewer than expected. Large mill drives, motor protection relays and modern switchgear usually measure power already. We read those first, then add meters only where a machine worth watching has none. A short survey in the first week lists what is there and what is missing.
How is this different from our SCADA trends?
SCADA shows power in kilowatts. It rarely joins that to tonnes and ore type, so it cannot say whether today's energy per tonne is good or poor for this ore. That join, and the ranking of gaps, is what submetering analytics adds. It also keeps the history, so this month can be set against the same ore last year.
Does iFactory control the mill?
No. It measures, compares and recommends. Mill control stays with your control system, any advanced control you run, and your operators. Recommendations need a person to act on them.
Does it work for gold, iron ore and crushing plants?
Yes. The method is the same wherever rock is crushed and ground: meter the machine, match it to tonnes, compare with what the ore should take. It also fits circuits with high-pressure grinding rolls or stirred mills. Only the expected figures change.
How long does it take to go live?
Six to twelve weeks from delivery. We need a place for the server with power and Ethernet, read access to your control system or historian, and a list of existing meters. A pilot normally covers the grinding circuit. To check your set-up first, contact our team.
Bring One Month of Power and Tonnage Data
In thirty minutes we show your kWh per tonne by machine, where the gaps sit and what each is worth. It works from data you already keep. You keep the picture whether or not you go further with iFactory.
- 1SAG and ball mill power trends
- 2Weightometer tonnes for the same month
- 3Ore type or hardness by day
- 4A list of the power meters you already have
- 5Your power tariff
