John Crane retrofitted a production-critical underflow thickener slurry pump at a major copper mining operation, an essential asset in the tailings circuit that moves high-density slurry from the thickener into the tailings transport system. The mechanical seal solution helped the site move away from frequent, high-risk maintenance interventions. The installation also marked a John Crane milestone: with a shaft diameter of approximately 270 mm, it is the largest slurry seal sold by John Crane to date.

The challenge

In this application, the Warman 550 pump operates at approximately 65% solids, making reliability essential and unplanned interruptions highly disruptive to production. Prior to the retrofit, the pump relied on a traditional stuffing box (packing) arrangement, an approach that, in abrasive service, accelerated wear on the shaft sleeve. Sleeve replacements were required roughly every four months, and those change-outs were major events, a full mechanical crew working across two shifts (around 36 hours), a 100-ton crane and extended exposure to safety risk and downtime risk. While the impeller and rubber liners were typically replaced on an annual interval, the sleeve failures forced additional intrusive maintenance throughout the year.

The solution

To address the reliability and maintenance burden, John Crane designed a mechanical seal package installed at the rear of the pump to replace the original packing arrangement, enabling a retrofit without modifications to the pump. The scope also included an adapter sleeve to suit the shaft. Because mining service can quickly challenge sealing systems, the package incorporated a controlled seal-flush arrangement to maintain a clean fluid environment at the seal faces, and it was specified with diamond-faced materials to provide added robustness if seal-flush pressure drops and solids enter the seal chamber.

The results

Following installation and commissioning, the sealed pump has been operating well, and early performance indicators show meaningful improvements in water usage and maintenance planning. 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 of water, indicating a reduction of roughly 12 m³/h, equivalent to approximately 288,000 liters per day, subject to site operating conditions.

Beyond water savings, the retrofit is designed to align maintenance with the site’s planned annual major service interval (when the impeller and liners are replaced), reducing the need for additional intrusive interventions during the year and supporting more predictable maintenance planning on a critical tailings asset.