The key link between mine excavation and the precise operation of electrowinning is the fact that industrial pumps are required to optimise both processes. One type of pump style – air-operated double-diaphragm (AODD) – has according to Wilden® Pump & Engineering Company been proven in the field “to be flexible enough to offer the ruggedness and reliability for operations such as mine dewatering, as well as the ability to handle corrosive chemicals during electrowinning operations.”AODD pumps are able to perform effectively at both ends of the mining spectrum because their method of operation allows them to easily handle variable flow rates and pressures, while being dry-run capable and nimble enough to transfer liquids that are shear-sensitive or high-viscosity, as well as slurries laden with rocks, pebbles and other particulates.The simple design of the AODD pump features few moving parts, which simplifies maintenance, while the pump’s seal-less design results in fewer leaks, which is a critical consideration when handling hard-to-seal or hazardous liquids. AODD pumps are available in both metal and plastic housing constructions, while a wide array of elastomers can be used in the diaphragms, which eliminates many chemical-compatibility concerns.“The wide variety of AODD pump configurations provides operational flexibility that can also result in optimised efficiency at many levels. The ability to feature AODD pumps in a wide range of applications, from basic general-use to delicate electrowinning processes, allows the operator to more cost-effectively outfit the mine. AODD pumps can also be less costly to operate, especially those models that are outfitted with next-generation mechanically actuated air distribution systems (ADS). And, at their most basic, AODD pumps excel in the typical rugged and harsh operating atmospheres found in mines, which reduces breakdown incidents along with corresponding downtime and repair costs.”Since AODD pumps do not require electricity to operate, they offer the added benefit of helping to improve mine safety, especially when used in potentially explosive atmospheres. AODD pump technology was invented by Jim Wilden in 1955, who went on to form Wilden Pump & Engineering in Grand Terrace, California. “Wilden’s AODD pump technology has been proven over the ensuing years to excel when used in the entire array of mining applications.”“Specifically, Wilden offers its Original™ Series and Advanced™ Series Metal and Plastic AODD pumps, which can be used for both dewatering operations and chemical transfer in electrowinning processes. Wilden’s Stallion® clamped metal AODD pumps incorporate many design enhancements that make them the first choice for various mine operations. Chief among these are a shock-absorbing polyurethane screen base that absorbs the impact from constant assault by solid particles, resulting in maximised durability. Stallion pumps also feature an integrated suction strainer, with the option of plumbed suction, if needed.”Stallion pumps also offer Wilden’s patented Pro-Flo X™ Air Distribution System (ADS) with the Efficiency Management System (EMS™). The EMS allows the user to control flow rates and air consumption with the simple turn of a dial. Wilden’s Stallion pumps are available in three sizes: PX4, 38 mm; PX8, 51 mm; and PX15, 76 mm. All are available in either aluminium or ductile-iron materials of construction, are submersible, intrinsically safe, lube-free, can run dry, have superior anti-freezing properties and can handle pressures to 125 psi. Depending on the model, flow rates range from 305 to 1,000 litres/min.Wilden also offers various Original and Advanced plastic AODD pumps in polypropylene or PVDF materials of construction, “which make them ideal for handling the oftentimes corrosive or hazardous acids, caustics or solvents used in electrowinning.” Elastomer options include Buna-N, Neoprene, Viton®, PTFE or Wil-Flex™. These pump models also have the ability to incorporate Wilden’s innovative new Pro-Flo® SHIFT ADS, the operation of which has been shown to produce up to 60% savings in air consumption and associated operational costs.Finally, Wilden has recently added the Advanced™ FIT Series AODD pumps to its product portfolio, which can be ideal for electrowinning and other chemical-handling applications within mining operations. Featuring stainless-steel or aluminum wetted paths, the Advanced FIT pumps have been designed to “fit” bolt-to-bolt and pipe-to-pipe within existing fluid-handling systems, making them an ideal drop-in replacement for either Wilden pumps or competitive models. The Advanced FIT pumps are also able to incorporate the Pro-Flo SHIFT ADS for increased savings in air consumption and operational costs.