Metso SAG Mill 6×2.7m

The Metso SAG Mill 6×2.7m is a semi-autogenous grinding mill designed for primary grinding in gold, copper, phosphate, and base-metal mineral processing circuits. With an effective grinding diameter of 6 metres and an effective grinding length (EGL) of 2.7 metres, this SAG mill configuration is suited for processing throughput rates of 200–800 t/h depending on ore hardness (SAG Power Index), feed top size, and product fineness target. Semi-autogenous grinding uses the ore itself as the primary grinding medium — supplemented by 8–12% steel ball charge — reducing the ore from primary crusher product (typically 150–200 mm) directly to the 80% passing 150–300 µm range required for downstream flotation or leach circuits in a single-stage or partial-reduction configuration.

Metso's SAG mill design incorporates a fabricated or semi-fabricated steel shell with thick replaceable liner segments manufactured from high-chrome white iron or rubber-metal composite materials. The variable-speed synchronous motor drive — connected via a low-speed gearbox or alternatively in a direct ring-motor (gearless) arrangement for larger mills — allows the mill speed to be adjusted between 72% and 80% of critical speed to optimise power draw and grinding efficiency across varying ore hardness conditions. Trunnion-supported bearing assemblies use hydrostatic-hydrodynamic oil film lubrication to eliminate metal contact at startup and under high-axial-load conditions, extending bearing service life well beyond roller-bearing designs.

At Maaden's Ad Duwayhi gold mine in the Makkah Region of the Arabian Shield, and at the Mansourah-Massarah gold project in Al-Qassim — two of Saudi Arabia's most significant gold mining operations — Metso SAG mills form the primary grinding circuit, reducing primary jaw crusher product to SAG mill discharge before regrinding in ball mills and passing to the cyanide leach circuit. The Ad Duwayhi plant processes 4,000 tonnes per day of gold ore at approximately 3.5 g/t Au, relying on reliable SAG mill operation for continuous production. Saudi Arabia's National Mineral Company (Maaden) has identified up to 30 significant gold deposits in the Arabian Shield under the Kingdom's mineral diversification strategy, and SAG mill technology will be central to processing plants for new deposits as they progress to production.

Razz Middle East works with Metso's process engineering and aftermarket teams to support Saudi mill operators with SAG liner assemblies, trunnion bearing inspections, and charge-level optimisation audits. Our regional presence in Riyadh and the Eastern Province allows rapid response to emergency parts requirements at remote mine sites in the Arabian Shield.