Gold mine in Indonesia installing KREBS® UMD™ Pumps to increase safety

By: Philippine Resources June 30, 2021

Article by Rachel Johnson - Photo Credit: FLSmidth: Krebs UMD slurry pump

A large gold mine in Indonesia set a goal to increase safety. As part of the goal, they evaluated the frequency and risk of site maintenance procedures to find areas where they could make changes. They found that their mill discharge pumps had shorter periods between maintenance events than planned, and researched further to find that the wet end components were not reaching the target wear life.

Every maintenance shutdown carried a low level of risk, but in a facility that processes 240,000 tons of ore per day, the frequent maintenance tasks added up to be significant. Site management decided that the time had come to investigate other pump options. The conditions the pumps were operating under were highly abrasive and severe, but management was hopeful that a safer and longer-lasting solution was possible. Safety would remain the top priority in any pump conversion plan, but if the downtime caused by pump maintenance could safely be reduced, the increase in production would be welcome.

The mine reached out to FLSmidth to ask if they had any solutions. FLSmidth responded with a proposal for a side by side comparison between the existing pumps and the KREBS Ultimate Mill Discharge (UMD) pump. For the comparison, FLSmidth would install a UMD pump at the discharge of one ball mill. The remaining mills would continue to operate with the existing pumps. During this same period, FLSmidth would set up a trial of different material combinations for the suction liner and wear ring in the UMD pump to make sure that the final recommendation would minimize maintenance events as much as possible.

The gold mine agreed to the proposal and FLSmidth installed a UMD 650×550 mm (26×22 in) pump at the ball mill discharge. The pump fed the highly abrasive discharge to a cyclone but it was designed for severe duty applications such as this. A trial was planned in phases to test different combinations of the suction liner and wear ring, with the materials for the impeller and casing remaining constant. At the same time as these materials were to be tested, all components would be compared with the wear experienced by the remaining discharge pumps.

Before starting the first phase of the trial, FLSmidth established targets that the life of the suction liner assembly would be 200% of the competitor pump, the life of the impeller would be 220% and the life of the casing would be 102%.

At the end of the first phase of the trial, the UMD pump was stopped to evaluate wear. Even wear was seen across the wear ring, but the suction liner showed little wear and could have been used longer. At this point, the suction liner assembly (which includes the wear ring) had already run 306% of the competitor’s suction liner life and with a new wear ring the suction liner could have lasted significantly longer. Regardless of remaining wear life for the suction liner, it was decommissioned to prepare for the second phase with a new wear ring and suction liner material.

After the first phase, the impeller and casing had significant life remaining, as expected. These parts had not reached the end of their wear life for the UMD or competitor pumps. New materials would not be tested in the trial so they were left in the pump to continue the comparison.

Component

Wear Life (%)  Competitor pump 24×20 

Target Wear Life (%)                      UMD 26×22               Run 1 & 2

Wear Life (%)         UMD 26×22            Run 1

Wear Life (%)            UMD 26×22            Run 2

*Suction Liner Assembly

100%

200%

306%

233%

Impeller

100%

220%

(still running)
**see note

270% (still running) **see note

Casing

100%

102%

(still running)
**see note

90% (still running) **see note

* KREBS® suction liner assembly contains the wear ring
** Note that the impeller and casing operated in both Run 1 and 2 and are still running. The current wear life percentages are shown in Run 2.

At the end of the second phase of the trial, the UMD pump was stopped again to evaluate wear. Significant uniform wear was seen on the suction liner, but the wear ring showed no signs of wear and could be used longer. The suction liner assembly had run 233% of the competitor’s suction liner life and the wear ring could last longer with a new suction liner. The suction liner assembly was decommissioned to prepare for the third phase with a new wear ring and suction liner material.

After the second phase, the impeller and casing still had significant life remaining so they were left in the pump to continue the comparison. At this point, the impeller had already lasted 270% of the life of the competitor’s impeller. The casing had so far lasted 90% of the life of the competitor’s casing, and with the wear seen it was anticipated that it also would reach or surpass the target wear life.

Phase three of the trial is ongoing and a fourth phase is planned, so the successes presented here will be surpassed as the best material combination for the UMD wear components is determined. Yet, the existing data shows that the UMD suction liner assembly lasts more than three times the life of the competitor’s liner and the impeller lasts more than 2.7 times the life of the competitor’s impeller.

The gold mine is pleased with the results they have already seen from the pump comparison and the added safety that they can expect when the trial is complete and they can proceed with converting the remaining discharge pumps. The added financial benefit of an increase in production due to the decrease in maintenance is also appreciated.


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