John Crane has retrofitted a mechanical seal on a large underflow thickener slurry pump at a major copper mining operation, reducing clean sealing water demand by around 288,000 litres per day.
The retrofit was carried out on a Warman 550 pump operating at approximately 65% solids. Underflow thickener pumps move high-density slurry from the thickener into the tailings transport system, making reliability central to both production continuity and safe maintenance planning.
Before the retrofit, the pump used a traditional stuffing box packing arrangement. Abrasive slurry service accelerated wear on the shaft sleeve, which had to be replaced roughly every four months.
Each sleeve change-out required a full mechanical crew across two shifts, around 36 hours of work, a 100-tonne crane, and extended intervention on a production-critical asset. Although the impeller and rubber liners were typically replaced annually, sealing-related work forced additional intrusive maintenance between major planned service intervals.
John Crane designed a mechanical seal package to be installed at the rear of the pump, replacing the original packing arrangement without requiring pump modifications. The package included an adapter sleeve to suit the shaft and diamond-faced materials to improve robustness if seal-flush pressure drops and solids enter the seal chamber.
“Underflow thickener pumps are among the most critical assets in a mine’s tailings circuit, so customers are understandably cautious about change,” said Warren Smith, Global Mining Market Director, John Crane. “This project is a practical example of how improved sealing can reduce maintenance exposure and cut the clean water required for sealing, while supporting more predictable planned maintenance.”
The seal-flush system was designed around approximately 11 m³/h at 75 psi, with actual operating flow running at approximately 7.5–8 m³/h. A parallel pump still operating with packing has been consuming around 20 m³/h, indicating a reduction of roughly 12 m³/h, equivalent to approximately 288 m³ per day, subject to site operating conditions.
By aligning sealing maintenance with the mine’s annual major service interval, when the impeller and liners are already replaced, the retrofit is expected to reduce additional invasive work during the year. With a shaft diameter of approximately 270 mm, the installation is also the largest slurry seal sold by John Crane to date.
Further information on John Crane slurry seals is available from the company.
