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joint. Teflon-coated O-rings provide a hydraulic pressure seal. CertainTeed offers the Yelomine piping system in versions suitable for both perma- nent and non-permanent applications, with a wide range of fittings available for changes of direction, branching and so on. The pipe can also be supplied with a series of drilled and tapped threaded holes to facilitate connection to spray systems. The company said that Yelomine is suitable for above-ground and buried applications, and with its easy-to-assem- ble, high-strength restrained-joint design, can be used in applications where con- ventional gasketed joints would pull apart. Certa-Lok products are optimized to with- stand tensile and compressive forces, as well as to maintain pressure, are quick and easy to assemble in all weather conditions, and are corrosion-resistant and require no solvent cements for assembly. Valves for Precise Flow Control For mining and minerals processing, Flowrox stated that its valves and pumps offer reduced total cost of ownership, sub- stantial savings through improved process performance and uptime, long service life- time, low maintenance costs, fast pay- back, and superior quality, reliability and wear resistance. Flowrox added that its automatic and manual pinch valves are an excellent choice for applications where extreme abrasion and scaling are present. The valve's construction ensures that it closes tightly, even if coarse particles remain inside the closing device, while in the open position, the valve is actually a part of the pipeline. The company pointed out that in some cases, the initial purchase cost for high- quality pinch valves may seem high, but the low maintenance costs will quickly turn the purchase decision into profit. In fact, in an ideal situation, compared to conventional valves used in mining and mineral processing, Flowrox claims its valves pay back their initial purchase cost in a matter of months. Its pinch valves are built from three main components: the sleeve, the body with mechanical closing bars, and the actu- ator, of which only the sleeve is in contact with the process medium. They are avail- able in sizes from 25 to 1,200 mm (1 to 47 in.), can operate at temperatures from -40° to 160°C, and can handle pressures from full vacuum to 120 bar (1,740 psi). Meanwhile, Flowrox's heavy-duty knife-gate valves are engineered to be used in shut-off applications involving abrasive or corrosive slurries, powders or coarse substances, giving 100% zero-leak- age downstream. Available in sizes of 50–600 mm (2–24 in.), they can work at temperatures of -40° to 135°C, and at pres- sures up to 20 bar. Benefits of both these types of valves include their good wear- and corrosion- resistance, no jamming or clogging during operation, their self-cleaning ability, trou- ble-free operation and long service inter- vals, Flowrox said. Turning to pumping requirements, the company noted that an increasing number of mine operators are discovering the bene- fits of peristaltic hose pumps as they endeavor to reduce water, energy and chemical consumption, and improve slurry transport reliability. While mining-sector pumping applications often involve abra- sive, corrosive, shear-sensitive and viscous liquid products, solids present the real chal- lenge, it added, and pump systems must be able to accommodate the variations in the solids content and composition. In addition, they must be capable of withstanding high operating pressures and flow rates to ensure smooth fluid transport, and deny the opportunity for the product to settle. Other required features should include repeatable and reliable delivery performance, self-priming functionality and low and easy maintenance. In peristaltic hose pumps, only the hose is in contact with the medium. No gland water or gland packing is needed; there is full vacuum capability, and no back-flow or slip. Materials are moved by positive displacement, with the pumps capable of reversible rotation. In terms of performance, these pumps have low wear and corrosion characteristics, can run dry, and are self-priming in suction-lift situa- tions, with no risk of cavitation. They also produce an exact flow each revolution, with low shear forces on the material being pumped. Lower Maintenance, Lower Power Usage Weir claims its Warman WBH centrifugal slurry pump offers lower maintenance, lower power usage, longer wear life and higher performance when compared with previous horizontal slurry-pump technol- ogy. A key feature is its one-point adjust- ment device, used to minimize the front impeller gap. Recirculation is reduced, leading to extended wear life while perfor- mance is maintained, the company stated. In terms of pipelines, Weir said its Linatex rubber hoses offer superior wear resistance and extended wear life when handling abrasive or corrosive materials. Its range includes soft- and hard-wall slurry and chemical mining hoses, dredge hoses, and a wide variety of preformed bends, reduc- ers and T-pieces. It also offers preformed hose bends that provide a replacement option for standard metal piping or for use in confined spaces when a standard hose cannot be curved, especially when abra- sion wear and vibration are an issue. Meanwhile, the company's Isogate pinch and gate valves are designed for use on pipelines carrying abrasive or corrosive materials. Sleeves are available in a variety of materials, including natural rubber, EPDM, nitrile, neoprene and others, and Weir noted that all of the valve wear parts are easily replaced in the field, reducing downtime and ownership costs. This article was adapted from an article that appeared previously in Coal Age's sis- ter publication, Engineering & Mining Journal (E&MJ;). o p e r a t i n g i d e a s c o n t i n u e d November 2014 www.coalage.com 53 This high-strength restrained-joint design can be used both underground and on the surface.