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High-tech Materials Maximize Pump Safety and Performance 136 E&MJ; • JUNE 2014 www.e-mj.com P R O C E S S I N G S O LU T I O N S Protecting the integrity of centrifugal process pumps used in critical applica- tions in mining is key to minimizing down- time and ensuring the safety of workers. Jacques Visser of Morgan Advanced Materials examined the various technolo- gies available for ensuring pump safety and how the use of modern materials and designs are bringing new dimensions of performance to these applications: Centrifugal pumps are widely utilized in most types of mining, primarily for the removal of slurry, but also for other tasks such as water removal. Their effective and continued operation is key, as any interruption can result in the undesired build-up of liquids in working areas, with the potential to compromise both process efficiency and the safety of operatives. However, the uniquely demanding conditions under which these pumps operate mean they can be subject to the build-up of pressure when, for example, suction or delivery valves become closed or operate incorrectly, or lines become blocked due to the presence of solids such as sand, grit or small pieces of rock. In these instances, the rapid increase in pressure can lead to the failure of a pump and, even worse, a pump explosion with the potential for severe injury or even death to operatives working nearby. The cost of a specialist replacement pump may be significant, as well as the cost of downtime while this critical com- ponent is sourced and installed, but even these costs pale in comparison with the financial and reputational damage result- ing from a workplace injury. The risk is illustrated by several well- documented cases, such as an incident at a U.S. coal mine when a fine coal transfer pump had been left standing for two days and was started without gland service water and quickly overheated. The pump was stopped by an operator, but the gland service water then entered the red hot all-metal casing, rapidly creating a build-up of steam that caused the pump to explode and the worker to lose his life. To combat this risk and to help maximize pump life, a variety of tech- nologies have been developed over the years designed to shut off operation before pressure within the pump reaches a level where it is prone to fail. Among them is the use of current-detection equipment, whose success is based on the premise that current drops when pump valves are closed. However, re- search on motors between 2 kW and 110 kW in duty has shown that there is fre- quently no relationship between the cur- rent change and the size of the pump, or the speed or duty of the motor, making this type of technology of questionable value in many applications. Another alternative is the use of pres- sure-sensing equipment, although once again a question arises as to the relation- ship between pressure at immediate delivery before and after valve closures or the occurrence of blockages. Further- more, any rise in pressure is only likely to be detectable at the point when the fluid starts to boil, which is by definition too close to the point at which the pump may explode. Meanwhile, any probes used with this equipment are likely to have their effectiveness hampered by the pres- ence of chemicals and slurries, while these systems are in the main considered an expensive option. The same issue also has the potential to cause issues with temperature-moni- Centrifugal pumps used in many mining and other industrial applications usually perform well under harsh condi- tions, but can fail or even explode when internal pressure rises suddenly due to line blockage or other malfunctions. EMJ_pg136-137_EMJ_pg136-137 6/2/14 3:21 PM Page 136