MATERIALS HANDLING
TUNNELING Major tunnelling projects involve the movement of large volumes of rock and soil as well as water. Te selection, operation and maintenance of pumps and related equipment can therefore have a significant impact on costs and schedule compliance. Water management involves removal of excess water as well as process water feed for machinery operation, dust suppression, etc. Initially, the construction site may need to be stabilised to prevent flooding of the work area, involving proactive as well as reactive dewatering. Te amount of water that needs handling can vary significantly depending on the site location, and seasonal conditions can also cause a need to increase or decrease dewatering activities. Tunnel boring machines and drilling equipment require a reliable supply of cooling water that, once utilised, must be recovered, extracted, and treated. Cuttings are also slurrified for removal and this may require pumps designed for high wear and large solids handling capability. Factors affecting design and material selection for pumps in mining, quarrying and tunnelling
SLURRY PUMPS Te majority of slurry pumps are centrifugal end suction or vertical shaft pumps. Key features are abrasion resistance through suitable materials, large clearances, large-diameter impellers for low operating speed to reduce wear, high hydraulic efficiency, and ease of maintenance. In long-distance pumping applications, high-pressure pumps are required to allow staged pumping. Froth pumps need to deal with
artificially increased flow rates due to the presence of air and must be self- venting design to prevent air locking. Conventional horizontal slurry pumps can be adapted for this or vertical shaft pumps with integral tanks designed to allow air venting. Gravel and dredge pumps are also types of slurry pumps and have much larger gaps between the impeller shrouds to enable large solids handling and have low NPSH characteristics as they often operate under suction lift conditions Process water pumps are usually ISO/ DIN/ANSI standard end suction pumps designed for high hydraulic efficiency and reliable operation. Chemical process pumps are standard ISO/DIN/ANSI end suction pumps designed for high hydraulic efficiency with a variety of material options to handle various chemicals within the process.
DEWATERING Several technologies may be used in dewatering applications, and the pumps can be of fixed or mobile installations. Mobile installations normally use submersible or self-prime skid-mounted pumps, whereas fixed installations can have horizontal end suction, multi-stage, or vertical shaft centrifugal or turbine pumps. Sulzer is a pump manufacturer
with a strong engineering heritage and a comprehensive worldwide
Ahlstarpump 40
www.engineerlive.com
service network. Its customers benefit from increased service intervals and exceptional reliability, supported by its wireless condition monitoring system. Optimised designs and reduced energy consumption deliver low operational costs and help to lower carbon footprints.
SNS process pump
MATERIALS TECHNOLOGY For abrasive slurry applications, white iron alloys and elastomeric materials are used. Where the carrier or process fluid in a slurry application is corrosive, a fine balance between erosive and corrosive wear is sought to find the optimal performance. Material selection is determined by a thorough analysis of the solids being handled, and material toughness may also need to be considered where large solids are encountered. Te majority of chemical process
pumps are of metallic designs in various stainless steels, duplex or super duplex alloys to suit the application. In some instances, non-metallic pumps may also be used where a metallic construction does not provide the required performance. Water pumps are more straightforward, with cast iron or stainless-steel alloys being most commonly used. Sulzer offers a comprehensive portfolio
of innovative pumps and agitators for mining, minerals and metals processing – from slurry to clear liquid. Te company’s equipment is tailor-made for challenging process conditions that include corrosive and abrasive liquids. A deep understanding of these applications, which involve handling harsh fluids, allows the firm to propose solutions that meet customer requirements.
Harvinder Bhabra is with Sulzer.
www.sulzer.com
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