Rebuilding a slurry line at 2,400 tonnes an hour

The call came in the way these calls usually do — not as a breakdown, but as a slow bleed. The concentrator had been holding 2,400 tonnes an hour on paper while the tails line quietly ate a set of wet ends every eleven weeks. Nobody had a failure. Everybody had a budget problem.

Mapping the wear before touching anything

We spent the first four days doing nothing but measuring. Ultrasonic thickness readings on every accessible spool piece, impeller and throatbush dimensions logged against install dates, and a pressure profile taken at six points along the line. The pattern that came out was not subtle: the second-stage pump was running well right of its best efficiency point, and the recirculation it caused was scouring the discharge elbow from the inside.

That single finding reframed the job. Replacing wet ends faster would have been treating the symptom. The line needed a duty change, and the duty change needed two valves that could actually hold position under slurry hammer.

What we changed

• Re-rated the second-stage impeller to move the duty point back toward BEP
• Replaced two failed knife gate valves with a heavier-seat variant held in Ulaanbaatar stock
• Relined the discharge elbow with ceramic-backed rubber rather than plain rubber
• Added two permanent thickness-check points so the crew can trend wear without scaffolding

The last item matters more than it looks. A measurement the crew can take in ten minutes gets taken. A measurement that needs a permit and a scaffold gets taken once, in a shutdown, when it is already too late to plan around.

The handover

We left with a one-page wear log taped inside the pump house door and a spares list agreed with the maintenance planner — five line items, all held locally. Eleven weeks later the crew sent us their own thickness readings. The elbow had lost 0.4 mm. On the old configuration it would have lost closer to three.