The elimination of recirculation within a slurry pump not only lowers power consumption but significantly reduces uneven wear on parts, and this, according to Morne Potgieter, Sales and Customer Service Manager of FLSmidth Krebs in South Africa, equates directly into an overall improved wear life of the pump, lowering spare parts stockholding, downtime and labour costs.The Krebs slurryMAX™ pump incorporates a unique patented feature which enables online adjustment of the critical impeller to suction side clearance and counters the primary leak path that occurs across the suction face of the impeller on conventional designs. The externally adjustable wear ring allows adjustments to be made while the pump is running, takes up the clearance at the impeller eye. This reduces the suction side recirculation and maintains the design flow while maintaining large clearances near the impeller shroud.This clearance at the impeller shroud eliminates the problem that conventional rubber lined pumps experience, namely pressure pulsations caused by the close proximity of the rotating raised expelling vanes to the suction liner, necessary to maintain flow, and the subsequently generated heat in the liner and rubber devulcanisation failure.Potgieter says that the ability to maintain the clearance between the impeller eye and the suction side of the pump also means that a constant delivery pressure and flow is provided throughout the life of the pump, and this contributes to increasing the life of the impeller.“Significantly, the wear ring need only be adjusted up to eight times throughout the life of the wet end parts, contributing to low total cost of ownership for the end user,” he points out.The extra-thick rubber lining has rigid reinforcement which prevents collapse onto the rotating impeller under upset vacuum conditions. Impellers are oversized in diameter and available in metal or elastomers. High pressure casings are available for specific application requirements such as multiple pumps in series.The pump casing is constructed of tough spheroidal graphite iron, while both the casing and suction inlets are heavy duty rubber lined. The impeller is made from either highly abrasion resistant high chrome white iron with a Brinell hardness of 680 to 720, or rubber. Potgieter explains that the high chrome impeller is resistant to tramp metals and capable of higher tip speeds.The pump bearing assembly is fitted with a reverse taper roller bearing which increases the effective load span thereby further improving the life of the unit. The centrifugal pumping action of the taper rollers discharges grease to the outside, preventing ingress of slurry or over greasing of the bearing. Both these have a positive impact on bearing life.Krebs slurryMAX™ pumps are suitable for applications ranging from mill discharge, SAG mill discharge recirculation, cyclone feed, general transfer of heavy duty abrasive slurries and tailings pumping. The pumps are available in sizes from 75 mm to 500 mm and are used across all commodities including copper, iron ore, gold, oil sands, sand and gravel and for industrial processing.