The HPGR resolves this through inter-particle comminution: compressive forces fracture the pebbles thoroughly and introduce internal microcracks, reducing the work index of material entering the ball mill

Decision Lens

The conventional SAG mill–cone crusher loop has a structural ceiling: hard, high-competency pebbles recirculate, load the mill, and cap throughput without a meaningful exit pathway. At Zijin Mining’s Julong copper operation, inserting three CITIC GM200-180 HPGRs after the SAG mill and cone crusher broke that ceiling — production climbed from 130,000 t/d to 160,000 t/d while system energy consumption fell 14.5%. The contradiction worth examining is that adding equipment to the circuit reduced energy per tonne and raised output simultaneously, challenging the typical cost-versus-capacity trade-off that operations directors face when evaluating comminution upgrades.

90-Second Brief

As the week closes, cITIC Heavy Industries installed three GM200-180 HPGR units at Zijin Mining’s Julong copper mine on China’s Tibetan plateau in 2023. Placed after the SAG mill and cone crusher to handle pebble recirculation, the units lifted crushing system capacity by 23% and reduced comprehensive energy consumption by 14.5%. The site operates at 4,300 metres altitude with low atmospheric pressure and significant temperature swings, conditions under which CITIC reports 24-hour continuous stable operation has been achieved. The outcome has been positioned as a replicable template for hard-rock SAG circuit upgrades at large-scale metal mines.

What’s Actually Happening

The root problem in a high-competency ore body is pebble accumulation. Fragments too large for mill balls but too small to be broken by larger ore in the SAG mill exit undersized, pass through the cone crusher, and return without reaching target fineness — cycling repeatedly, consuming energy, and generating excess fines from fresh ore in the process. The HPGR resolves this through inter-particle comminution: compressive forces fracture the pebbles thoroughly and introduce internal microcracks, reducing the work index of material entering the ball mill.

At Julong, the HPGR product P80 reached as low as 3 mm. That particle size and the associated microcracking meant the ball mill received material that was both finer and pre-weakened, driving a 25% reduction in SAG mill unit energy consumption and a 16.2% reduction in ball mill unit energy consumption. A further cascade effect: with the HPGR absorbing pebble duty, the upstream cone crushers could operate at a coarser discharge setting, reducing liner wear and extending service life — a maintenance cost benefit separate from the energy and throughput gains.

Why It Matters for Mining Operations Directors?

For operations running SAG-based circuits on competent or variable-hardness ore bodies, Julong is a direct operational reference, not a laboratory result. The 30,000 t/d capacity gain was achieved without replacing the primary SAG mill — a far larger capital and shutdown commitment — by retrofitting HPGRs into an existing circuit, which is a structurally different capital decision from a greenfield comminution design.

Energy cost is the other material implication. Operations directors facing pressure on AISC contribution from energy inflation have a concrete data point: a 14.5% reduction in system energy consumption at scale, on hard rock, in an extreme environment. If your processing plant is energy-constrained or cost per tonne processed is being driven by SAG mill power draw on competent ore, the mechanism demonstrated at Julong is directly analogous.

The altitude and temperature conditions at Julong — 4,300 metres, significant thermal swing, low atmospheric pressure — also matter for operations in comparable high-altitude jurisdictions. Equipment rated for sea-level conditions routinely underperforms at elevation; CITIC’s report of stable 24-hour operation provides some evidence of adaptability, though the specific adaptation measures are not detailed in available reporting.

The Forward View

CITIC’s framing of Julong as a “replicable technical solution” signals commercial intent to extend this circuit design to other large metal mines. For operations directors, the near-term implication is that HPGR vendors will increasingly present pebble-crushing retrofits as a throughput-unlock pathway rather than a new-build comminution option. Evaluating those proposals will require site-specific data on ore competency, existing SAG loading patterns, and available footprint for HPGR installation.

The secondary signal is on downstream beneficiation. The microcracking effect and improved mineral dissociation efficiency documented at Julong suggest potential recovery benefits in the flotation circuit — a claim worth testing against site-specific mineralogy before accepting it as transferable. If recovery improvement can be demonstrated alongside throughput and energy gains, the business case for HPGR retrofits strengthens materially.

What We’re Uncertain About?

  • Adaptation detail at altitude: CITIC references a “series of adaptation and optimisation” measures to achieve stable operation at 4,300 metres, but the specific engineering modifications are not disclosed. Operations directors at high-altitude sites cannot assume standard sea-level specifications will perform equivalently without understanding those adaptations.

  • Recovery improvement magnitude: The source confirms microcracking and improved mineral dissociation efficiency in beneficiation, but does not quantify the actual recovery rate change in the flotation circuit. A confirmed recovery uplift would be the most operationally significant number not yet in the public record; plant metallurgical data over a full operating period would resolve this.

  • Capital payback period: Throughput and energy outcomes are documented, but installed cost, shutdown duration for integration, and payback period are not reported. These are the inputs required to convert this result into an investment recommendation for corporate approval.

  • Transferability to other ore types: Julong is a high-hardness hard-rock copper ore body. Performance on softer, more variable, or clay-bearing ores is not addressed. Operating context matters before extrapolating to dissimilar deposits.

One Question to Bring to Your Team

If our SAG mill is capacity-constrained and pebble recirculation is measurable, what is our current unit energy consumption per tonne of ore processed — and do we have enough footprint and circuit data to model whether an HPGR retrofit would replicate the Julong throughput and energy outcome at our specific ore competency?

Sources

  • Im-mining — CITIC Heavy Industries reports on successful installation at Zijin’s Julong copper mine (Link)

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