Flow control technology company John Crane has retrofitted a mechanical seal on an underflow thickener slurry pump at a major copper mining operation, reducing the clean water required for sealing by an estimated 288,000 litres per day while supporting a shift towards less frequent maintenance on a production-critical asset.
The project involved the replacement of a traditional stuffing box packing arrangement on a Warman 550 pump used in the mine’s tailings circuit. Underflow thickener pumps transport high-density slurry from the thickener to the tailings handling system and are regarded as critical infrastructure, with reliability directly affecting production continuity.
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According to John Crane, the pump operates at approximately 65% solids concentration, creating highly abrasive conditions. Under the previous sealing arrangement, shaft sleeves required replacement roughly every four months because of wear. Each replacement involved a full mechanical crew working across two shifts, the use of a 100-tonne crane and around 36 hours of maintenance activity.
The company developed a mechanical seal package that could be installed without modifications to the existing pump. The retrofit included an adapter sleeve and a controlled seal-flush system designed to maintain a clean environment at the seal faces. The seal was also specified with diamond-faced materials intended to withstand occasional ingress of solids if seal-flush pressure falls.
Following commissioning, the sealed pump has been operating with seal-flush flows of approximately 7.5–8m³/h, compared with around 20m³/h for a parallel pump still using packing, according to the company. Based on those operating conditions, John Crane estimates water savings of approximately 12m³/h, or 288m³ per day.
The company said the retrofit was designed to bring seal maintenance into line with the site’s annual major service interval, when impellers and liners are replaced, reducing the need for additional maintenance shutdowns during the year.
“Underflow thickener pumps are among the most critical assets in a mine’s tailings circuit, so customers are understandably cautious about change,” said global mining market director Warren Smith. “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.”
