( Virtual Showroom ) When Anglo American Platinum’s Mogalakwena mine in South Africa’s Limpopo province wanted to extend the wear life of shaft sleeves in its Warman® pumps, Weir suggested the application of the J221 premium wear-resistant overlay hardened shaft sleeve.

Testing was conducted on a Warman® MCR® 450 slurry pump at the North Concentrator to improve sleeve and packing wear life under conditions of contaminated or sub-optimal flush water. The J221 shaft sleeve’s trial performance was exceptional, lasting 14 240 hours under conditions of both regular operations and extensive pump sliming. This was an almost 10-fold improvement on the standard shaft sleeve. The solution has led to savings in both downtime and spare parts.

Following the successful results, LeRoux Esterhuyse, Engineering Manager at the Mogalakwena North Concentrator, reported: “Excited about the trial performance of the hardened shaft sleeve; let us roll it over to all primary and secondary mill discharge Warman pumps.” The J221 sleeves have since been implemented across all primary and secondary mill discharge pumps at Mogalakwena.

As the world’s preeminent open pit platinum mine, Mogalakwena prides itself on its low operating costs and its commitment to initiatives that bolster throughput while curtailing expenses. Platinum ore mined at the various Anglo American Platinum operations is milled at the new Mogalakwena North Concentrator – in operation since 2007 – and the older Mogalakwena South Concentrator.

The challenge faced was that the primary and secondary mill discharge pumps, a mix of Warman® AH® 20/18 and Warman® MCR® 450 slurry pumps, were being overhauled frequently due to the extreme wear on the C23 shaft sleeves. The pumps had to be stopped monthly to change out the shaft sleeve, with services carried out by the Weir on-site service team. Weir has had a service agreement with Mogalakwena Complex – comprising the Mogalakwena North and South concentrators – for 14 years, with a field service team reporting daily to both sites.

The Weir team determined that the wear life of the C23 shaft sleeve was 3 864 hours under standard operating conditions and only 1 440 hours under conditions of extensive pump sliming. This occurs when there is inadequate gland water pressure in the pump stuffing box, causing slurry to breach the packing between the shaft sleeve and the packing rings.

When the gland packing is compromised like this, the slurry erodes grooves into a standard shaft sleeve. Once these grooves develop, the packing can no longer form an effective seal on the shaft sleeve. This situation requires the shaft sleeve to be replaced, reducing the equipment’s availability.

The J221 premium wear-resistant overlay is ideal for highly abrasive and erosive wear environment, due to the high density of the tungsten carbide particles in the matrix. The overlay boasts uniform carbide distribution with low porosity, and hardness levels up to 70 HRC.

Weir Minerals Africa