Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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D E W AT E R I N G into the atmosphere, wasting energy and falsely inflating operating costs. Models with unbalanced valves are built with a large diameter on one end of the valve and a small diameter on the opposite end to create the optimal pressure difference. Since the valves are biased toward one side, they do not leak, center or stall the pump—even under low air inlet pressures. Unbalanced valve designs also produce a consistent material flow, which increases reliability and prevents unscheduled downtime. Many diaphragm pumps stall when they are submersed in fluids. This can be prevented by using a pump that has a one-way exhaust check valve. The exhaust check valve prevents water— and other types of contamination—from entering the air motor system, and enables the pump to function while it is fully submersed. This feature gives customers the versatility to drop the pump directly into the pit, instead of setting up the pump on the surface level and dropping a tube into the hole to extract the standing water. Often, workers are forced to set up the dewatering pump on rocky or uneven terrain in order to remove standing water from a pit. If the pump tips over before it starts running, it will not operate properly and may leave surface water behind. It is important to select a diaphragm pump with an integrated base plate to ensure it operates effectively on soggy and unstable terrain, which is common in the mining environment. Routine maintenance is the key to keeping diaphragm pumps running reliably. The frequency of the maintenance schedule should be based on the performance of the product, instead of hours of operation or millions of cycles. It is time to perform routine maintenance activities if the pump displays any of the following behaviors: • Reduced performance, which may indicate air leakage in the motor; • Fluid leakage, which may indicate a ruptured diaphragm; or • Reduced fluid output, which may indicate ball or seat deterioration caused by abrasive materials. Pumps performing severe applications and/or moving abrasive materials require more maintenance than those used for general and non-abrasive applications. Choosing a pump with a lube-free motor also reduces the www.e-mj.com amount of maintenance required to keep it operating effectively. Selecting Features that Increase Durability Diaphragm pumps are put to the test in harsh mining environments. They have to be durable to withstand sediment and potentially abrasive fluids inherent in the dewatering application. Ingersoll Rand recommends contractors select a pump that can handle up to 1-in. (25mm) particles to prevent stone, rocks or clay from clogging the system. Over time, this sediment can create holes in the diaphragm pump as it moves through the system. If this occurs, contractors may notice fluid leaking from the manifold and reduced fluid discharge pressure. It is important to choose a pump with heavy-duty ball guides and manifolds that resist abrasive and semi-solid materials as they pass through the pump, to prevent leaks and extend the life of the product. To help prevent leaks, customers should use diaphragm pumps with bolted, instead of banded, fluid caps. These models use a bolt to squeeze the air and fluid caps to the diaphragm, which creates an even clamping surface and a barrier to prevent leaks. Bandeddesign pumps use a clamp to hold the air and fluid caps to the diaphragm. The band degrades over time, allowing potentially harmful fluid to leak into the work environment. Choosing the Right Pump for the Application Given the number of diaphragm pump options in the market, it is important for end users to evaluate their requirements for casing materials, port sizes, power options, features, maintenance needs and total cost of ownership prior to making a purchasing decision. Ingersoll Rand recommends air-operated diaphragm pumps with aluminum casing, a removable screened filter and one-way exhaust check valve for mining applications. An interactive pump selector guide is available at ingersollrandproducts.com/amen/products/fluid/aro-pump-selector to help customers select the right pump for their next mining project. Boyce (Ken_Boyce@irco.com) is product manager of the ARO diaphragm pump portfolio at Ingersoll Rand. AUGUST 2013 • E&MJ; 37