Model Predictive Control + Process Digital Twin

Mill more tonnes through your SABC circuit — without overloading the SAG.

Aeterna Automation runs a live digital twin of your SAG mill, pebble crusher, and ball mill, and drives it with model predictive control — so the circuit holds its true throughput limit at lower energy per tonne. Live in weeks.

+3–8%
circuit throughput
5–12%
lower kWh / t
<6 wks
to closed loop
SAG_MILL_LOAD · % OF OVERLOAD LIMIT MPC LIVE
OVERLOAD LIMIT MPC ENGAGED →
Manual control — load kept low to avoid overload; throughput left on the table Aeterna MPC — load held tight at the limit, maximum stable tonnes
Runs on your existing control system
OPC-UA / DCS / PLCVSD on SAG & ball mills AVEVA PI & historiansNo new instrumentationOn-prem / edge
Where the tonnes go

Grinding is your biggest energy bill — and your tightest bottleneck.

Comminution is often the largest single energy consumer on site. Operators protect the SAG from overload and grind-out by running well below its real limit, and ore that changes hardness by the hour makes that limit a moving target.

01 · OVERLOAD RISK

The SAG runs scared

Fear of overload and slurry pooling keeps mill load conservative. The safety margin is unmilled tonnes you pay for in lost throughput every shift.

02 · ORE VARIABILITY

Hardness keeps moving

Feed hardness and size shift constantly. Manual setpoints can't chase it, so the circuit is rarely at its true optimum for long.

03 · RECYCLE & GRIND

Recycle and P80 fight you

Pebble recycle load and cyclone overflow grind size pull against throughput. Pushing one usually upsets another without coordinated control.

The sensing layer

Measure the feed before it reaches the mill.

The Rock Analyzer reads feed particle size on the SAG feed conveyor, continuously — turning the circuit's largest disturbance into a measured signal the twin and the controller act on ahead of time.

Rock Analyzer · sense Digital Twin · model MPC · control
ROCK ANALYZER · RA-01 SCANNING FEED CAM SAG FEED CONVEYOR 4.2 m/s → to SAG LIVE SIZE DISTRIBUTION LIVE PSD F80118 mm TOP240 mm +25 mm68 % OVERSIZE4 % F80 fine coarse →
Feed intelligence

Machine-vision feed sizing

A non-contact camera over the feed belt sizes every parcel of ore as it passes, reporting the full distribution — fines through top size — every few seconds.

  • Continuous particle size distribution — F80, size fractions, and top size on the moving belt
  • Feedforward to the MPC — the controller pre-positions feed rate, mill speed, and water for the incoming size, anticipating overload instead of chasing it
  • Live twin calibration — measured feed size re-anchors the breakage model so the digital twin tracks the real ore
  • Coarse & oversize alerts — flags coarse surges and primary-crusher gap drift before they reach the SAG
How it works

A live twin of the circuit. Predictive control on top of it.

Aeterna mirrors your SABC circuit as a continuously calibrated digital twin, then runs multivariable MPC against it — coordinating feed, water, mill speed, and pump and cyclone setpoints to hold the bottleneck without breaching any constraint.

PROCESS DIGITAL TWIN · SABC CIRCUIT VIEW SYNCED TO PLANT
OVERSIZE PEBBLES → RECYCLE UNDERFLOW CIRCULATING LOAD 260% PEBBLE CRUSHER recycle 340 t/h M PT 22 JT 23 FV 26 WT 21 SC 25 MPC PREDICTIVE SAG MILL load 96% · 13.1 MW · filling 31% SCREEN SUMP / PUMP CYCLONE CLUSTER M BALL MILL 8.7 MW TO FLOTATION P80 152 µm ✓ FRESH FEED 2,140 t/h STREAM TYPE solids (feed · pebbles) slurry (mill · cyclone) product at target P80 DIGITAL TWIN: mass balance · mill filling (soft sensor) · power draw · P80 prediction — calibrated live
Foundation

Process digital twin

A continuously calibrated model of your full SABC circuit that stays in sync with the plant — the trustworthy picture the controller acts on.

  • Soft sensors infer mill filling, slurry density, and product P80 between lab assays
  • What-if simulation to test setpoints, ore blends, and ball charge before touching the plant
  • Operator-training mode that mirrors real circuit dynamics
  • Early warning on overload, grind-out, and recycle build-up
The controller

Model predictive control

Multivariable MPC that looks ahead, predicts constraint violations before they happen, and moves every handle together to hold the bottleneck.

  • Coordinates feed rate, mill speed, water, and pump & cyclone setpoints as one problem
  • Maximizes throughput against SAG load, motor power, and recycle limits
  • Holds target grind size while ore hardness and feed size drift
  • Operator-supervised advice first, then closed-loop on your terms
Why Aeterna is faster

From historian to closed loop in weeks.

We calibrate the twin from your own historical and live data instead of a months-long manual modeling campaign — so MPC reaches closed loop while a traditional project is still scoping.

STEP 01

Connect & calibrate

Read circuit tags over OPC-UA and auto-calibrate the digital twin to your ore and equipment. No new sensors.

Days 1–10
STEP 02

Validate

Twin checked against history and soft-sensor benchmarks, with what-if runs reviewed alongside your metallurgists.

Weeks 2–3
STEP 03

Control

MPC online as operator advice, then closed loop. Operators stay in command; Aeterna holds the limit.

Live by week 6
Typical outcomes

What coordinated control is worth.

Representative ranges for SABC circuits. Your numbers depend on ore, circuit, and current variability — the calculator below estimates yours.

+3–8%
throughput at target grind
5–12%
lower grinding energy per tonne
40%+
reduction in P80 variability
<6mo
typical simple payback
What Aeterna controls

Every handle in the circuit, coordinated.

SAG mill

feed rate · mill speed · water · load

Hold mill load and motor power at the overload limit for maximum stable tonnes, adapting to feed hardness in real time.

Pebble / recycle crusher

recycle load · critical-size buffer

Manage recycle so critical-size material is crushed and returned without choking the SAG or starving the crusher.

Ball mill & sump

density · sump level · pump speed

Stabilize slurry density and sump level, keeping the secondary mill fed and protecting pumps from upset.

Cyclone classification

target P80 · circulating load

Hold overflow grind size on target and manage circulating load so downstream recovery gets the size it needs.

Worked example · live gold price

What the circuit is worth on a gold operation.

A 5 Mt/a gold plant, valued at the current spot gold price. The figure is the incremental gold revenue from the modeled throughput uplift — lower energy per tonne and recovery gains are additional upside.

Scenario assumptions
Ore milled5.0 Mt / yr
Head grade1.0 g/t Au
Recovery90%
Gold output (base)~144,700 oz / yr
Throughput uplift (MPC)3 – 8%
Spot gold price
fetching live price…
Estimated annual benefit
incremental gold revenue from a 3–8% throughput uplift, at today's spot gold price
Added gold output
Gold price (live)
Base production144,700 oz/yr
Get a validated estimate for your circuit

Gross incremental gold revenue at the live spot price; it excludes operating cost per tonne and the additional upside from lower energy per tonne and recovery gains. A site study produces a net, plant-specific figure.

Proof

Closed loop in 5 weeks. Paid back in 4 months.

“The twin was matching our circuit inside two weeks, and MPC was holding SAG load tighter than any operator could by hand — at higher tonnes.”

— Metallurgy Superintendent, copper concentrator
(reference available under NDA)

+5.6%
circuit throughput
−9.1%
grinding kWh / t
5 wks
to closed loop
4 mo
simple payback

See the twin built on your circuit.

Send us a tag list and a slice of history. We'll stand up a digital twin of your SABC circuit and show you what MPC is worth — before you commit to anything.

Request a demo