Mines can’t function without pumps and pipework. Period. At the front end of an operation, dewatering is key to maintaining production, be it from underground or an open pit. By the time run-of-mine coal enters the processing plant, slurries need transporting. Even with gravity-fed plants where the flow sheet runs sequentially downhill, there will be some need for recycling material involving both pipework and pumping. Within the plant, reagents have to be handled, separated flows directed to the appropriate next treatment stage, and at the end of the whole proceedings, tailings deposited and reclaimed water recycled.
Each of the components involved in handling fluids that can be corrosive and abrasive have specific requirements in terms of the materials used in their construction, while the aim is always to keep maintenance and repair costs to a minimum. Manufacturers today offer pumps, pipework and valves made of materials that are appropriate to the duty required, with heavy investment having gone into developing new metallurgy that can provide better service at lower overall cost. Lighter weight plastics are also playing an increasingly important role, especially in pipework, while the reliability of valves has improved over the years, giving more precise control over fluid flows of all types.
Coal Age asked a number of the leading international suppliers of fluids-handling equipment for an update on their current product offerings. Here are some of their responses.
QUICK-FIT PIPES WITH A LONG HISTORY
Victaulic manufactures a range of pipe-joining solutions for the mining market that, it said, offers faster, safer and more efficient assembly of piping systems. From a mine owner’s perspective, using Victaulic pipe can cut installed costs by up to 50%, it claims, while its products are safer and faster to install, reducing the opportunity for injuries. This type of pipe system can also cut maintenance times significantly, keeping plants running more efficiently. For piping installers, they have the advantage of faster installation without the need for special tools, while the availability of reusable parts speeds up maintenance.
The company noted that in the U.S. and Canada, grooved mechanical piping is the generally accepted method for joining pipe in the mining industry. The mechanical joint consists of four elements: grooved-end pipe, a gasket, coupling housing, and nuts and bolts. The primary and perhaps best known benefit of these systems is that they are three to five times faster to install than other methods of pipe joining, while the couplings can be orientated in any direction during installation, making it easier to install pipe ranges in tight spaces.
Another benefit of Victaulic grooved products is the ease in rerouting and expanding piping systems, the company said. Where piping systems need to be repositioned and extended, the ability to disassemble and reassemble piping components quickly and easily means that system retrofits and expansions can be completed fast.
Victaulic products include its original groove system, introduced in the 1920s, the advance groove system, and the Vic-Ring system for large-diameter slurry and tailings lines, as well as high-pressure and fire-protection systems.
Underground mines use the installation-ready Style 177 flexible couplings (See Product News, p. 57) that greatly reduce the risk of pinched gaskets — compressed air leaks can cost thousands of dollars a year in additional energy costs. In processing plants, rigid and flexible advanced groove system couplings are used on abrasive slurry pipelines, using the Victaulic Vic-Ring piping method to maintain the full pipe-wall thickness.
In Australia, a recently installed conveyor structure at Rio Tinto’s Tom Price mine has been equipped with Victaulic FireLock products on its 6 in. and 8 in. (152- and 203-mm) fire-protection pipelines. The company noted that these were chosen to provide an approved rigid joint that could be installed easily without the need for on-site welding. It also helped minimize the time that the installation crews spent exposed to the extreme outdoor heat conditions of the Pilbara.
|Victaulic’s joining solutions offer faster, safer and more efficient assembly of piping systems.|
PVC PIPING SYSTEMS FOR MINING
A Saint Gobain group member, U.S.-based CertainTeed Corp. reported that it helped to pioneer the development of PVC pipe more than 30 years ago. Today, the company offers piping products for underground coal mining that feature the Certa-Lok Yelomine restrained-joint pressure piping system.
Engineered with high-impact strength, ultraviolet protection and ease of assembly, the Yelomine system comes in standard 20-ft. (6.1-m) laying lengths, with other lengths available. Yelomine pipe is manufactured with IPS outside diameters, in pressure classes from 90 to 315 psi (6 to 22 bar). The system utilizes precision-machined grooves, which, when aligned, permit the insertion of a high-strength, thermoplastic spline to create a fully circumferential, securely locked restrained joint. Teflon-coated O-rings provide a hydraulic pressure seal.
CertainTeed offers the Yelomine piping system in versions suitable for both permanent 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-assemble, high-strength restrained-joint design, can be used in applications where conventional gasketed joints would pull apart. Certa-Lok products are optimized to withstand 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.
|This high-strength restrained-joint design can be used both underground and on the surface.|
VALVES FOR PRECISE FLOW CONTROL
For mining and minerals processing, Flowrox stated that its valves and pumps offer reduced total cost of ownership, substantial savings through improved process performance and uptime, long service lifetime, low maintenance costs, fast payback, 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 actuator, of which only the sleeve is in contact with the process medium. They are available 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-leakage downstream. Available in sizes of 50–600 mm (2–24 in.), they can work at temperatures of -40° to 135°C, and at pressures 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, trouble-free operation and long service intervals, Flowrox said.
Turning to pumping requirements, the company noted that an increasing number of mine operators are discovering the benefits 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 abrasive, corrosive, shear-sensitive and viscous liquid products, solids present the real challenge, 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 situations, 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 technology. A key feature is its one-point adjustment device, used to minimize the front impeller gap. Recirculation is reduced, leading to extended wear life while performance 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, reducers 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 abrasion 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 sister publication, Engineering & Mining Journal (E&MJ).