Metso GP220 Mantle

C (Coarse): ~820–850 kg (1,800–1,870 lbs) | M (Medium): ~760–790 kg | F (Fine): ~700–730 kg | EF (Extra Fine): ~650–680 kg. LIFT PLANNING CRITICAL: Exceeds standard 5t hoist capacity on many plants. Requires 10t+ overhead crane or mobile crane. Verify NW Rapid portable plant gantry capacity before scheduling change-out.

The GP220 head cone has a large backing volume. You need 45 – 65 liters (12 – 17 gallons) of two-component epoxy backing (Metso KrushMore, ESCOBACK 6000, Copps K-Back). Order a dedicated "GP220 Mantle Backing Kit" (typically 2–3 x 25L pails). Critical: Head cone seat must be pristine (no old backing, oil, or moisture). Pre-heat pails to 25–30°C for flow; pour in one continuous operation to avoid cold joints on this volume.

The GP220 uses a Heavy-Duty Hydraulic Lock Nut (Single or Double Stage, ~M105/M110 thread). Blue-Match: Head cone seat & mantle bore >95% contact (Prussian Blue). Any low spots = future fretting. Lubricate: Copper/graphite anti-seize on THREADS ONLY (Never on spherical seat). Seat: Run nut down until mantle seats fully (verify zero gap at spherical seat with 0.03mm feeler gauge). Pressurize: Apply hydraulic pressure to Metso Spec (Typically 300–350 bar / 4,350–5,075 psi). Use calibrated gauge/hand pump. Lock: Engage mechanical locking set screws/pins per manual. Re-pressure Checks - MANDATORY: 2 Hours (Hot), 24 Hours, 72 Hours. The 450kW long stroke generates massive cyclic thermal expansion/relaxation. Skipping the 2hr check is the #1 cause of mantle spin/head damage.

SAG pebbles are work-hardened (300–400 BHN), high-silica (60%+), and angular. The GP220 parallel zone subjects the mantle to extreme sliding compression abrasion (not just impact). Standard Mn18Cr2 relies on work-hardening (slow, requires strain) and suffers rapid micro-gouging/spalling. TiC Composite provides instant 550–620 BHN via dispersed Titanium Carbides, resisting the "sandpaper effect" of pebbles sliding in the parallel zone. Typical life uplift: 3x–4x (e.g., 3 weeks Mn18Cr2 → 10–12 weeks TiC). On the circuit constraint crusher, this eliminates 6–8 extra shutdowns/year.

Absolutely not. Catastrophic mechanical interference guaranteed. GP220 Mantle: Steep head angle (~50-55°), long parallel zone, constant stroke geometry, specific spherical seat ID. HP Bowls: Shallower cavity, pivot-point geometry, hydraulic lock bowl seat, different thread/flange. Result: Mantle will contact bowl liner immediately (wrong profile), destroy locking mechanism, eject tramp iron hazard, write off head cone & adjustment ring. GP Mantle ONLY pairs with GP Bowl Liner (Same Model/Size).

1) Feed Distribution (Primary Cause on NW Rapid): Worn/misaligned feed chute or missing distributor feeds 70%+ load on one side. Fix: Rebuild chute, install rotating distributor before new mantle. 2) Countershaft Bushing Wear: Excessive radial clearance (> 3mm) allows eccentric "whip" on the long stroke. Fix: Replace bronze bushings preventatively at every 2nd mantle change. 3) Head Cone Seat Damage: Previous mantle spun/fretted seat. Fix: Machine/Blue-match seat to >95% contact (costs ~5k, saves~60k head). 4) Hydraulic Nut Pressure Loss: Nut backing off due to missed 2hr/24hr re-pressure. Fix: Strict adherence to re-pressure schedule.

Change at FIRST limit (Matched Set Policy - Non-Negotiable on GP220): Parallel Zone / Heel Thickness < 25–30 mm (1.0–1.25"). CSS Drift > 4–5 mm wider than target setting. Product Flakiness Index > 12–15% (loss of parallel zone geometry). Throughput Drop > 12% (profile worn to "hourglass"). Visual: Radial cracks in lower 1/3 (thermal fatigue), severe gouging/pitting, or heel flaring (OD growth). GOLDEN RULE: On GP220, ALWAYS change Mantle & Bowl Liner as a matched set. The steep cavity/long stroke amplifies "step wear" mismatch exponentially. Running new Mantle on worn Bowl (or vice versa) destroys the new liner in < 35% of normal life and induces uneven loading that cracks the Adjustment Ring / Head Cone.