Pumps, along with electric motors and air compressors, are among those ubiquitous items of support equipment that may not be directly involved in coal mining or processing, but are still critical to the mission. 

In underground applications small, lightweight dewatering pumps are generally used to pump water from sumps to larger, centrally located stage pumps. According to pump builder ITT Flygt, dewatering pumps rated up to 6 kW (8 hp) are typically used at the faces, up to 20 kW (26 hp) for stage pumping, and up to 90 kW (120 hp) for feeder pumping between intermediate levels.  Depending on whether clean, “top” water from the shaft bottom or both water and accumulated solids are being pumped, mines can use either high-head submersible drainage pumps or, if slurry specific gravity is more than 1.1, a solids-handling slurry pump.

Submersible pumps are widely available in electric- or hydraulic-power versions, with the latter driven by diesel power packs. Each power choice has certain advantages and drawbacks: Electric pumps, for example, can handle high fluid volumes or high heads, but they usually operate at high rpm levels and for that reason, can be susceptible to rapid wear when the pumped water contains significant amounts of silt. Hydraulic models also are capable of handling either high volumes or high heads, and are generally more resistant to wear from particulates in the water. They do, however, need regular refueling and require additional maintenance related to the diesel power pack.

As described below, recent model introductions from well-known suppliers such as Godwin Pumps, Gorman-Rupp and Tsurumi, among others, have extended the depth and range of pump choices for underground dewatering applications.

Godwin Moves Ahead with Heidra
Godwin Pumps recently announced two additions to its Heidra hydraulic submersible pump line: the HS80HH and HS150HH models. The HS80HH is a compact, self-contained pumping unit featuring a 3-in. (75-mm) submersible hydraulic top-discharging pump and a diesel-driven power pack. The HS80HH, according to the company, offers operating efficiencies that cannot be matched by standard electric submersible models. With variable-speed diesel engine power, the Heidra HS80HH can meet a variety of flow and head requirements up to 450 gal/min (102 m³/h) and 325 ft (99 m) of total dynamic head with a simple throttle adjustment. It can handle solids up to 25-mm diameter.

The HS150HH hydraulic submersible pump also is a compact self-contained pumping unit featuring a 6-in. (150-mm) hydraulic pump end and diesel power pack. As with its smaller stable mate the HS80HH, variable-speed diesel power allows the bigger HS150HH to meet a variety of flow and head requirements up to 1,250 gal/min (285 m³/h) and total dynamic head requirements up to 460 ft (141 m). In addition, it has the ability to handle solids up to 35 mm in diameter. Both the HS80HH and HS150HH feature dry running capabilities and cast chromium steel impellers.

In a related development, during a recent tradeshow, Godwin said it would incorporate ITT impeller designs and remote pump monitoring technology into its Dri-Prime pump line. In particular, impeller technology used in ITT’s larger submersible pumps will be integrated into Godwin’s design package for better performance  in dewatering applications involving solids.

ITT Corp. acquired Godwin pumps in 2011, adding it to the Flygt and Grindex lines in its Water & Wastewater business group.

Flygt continues to refine its 2600 series of dewatering pumps, introduced in 2006. The pumps in the series offer motor sizes from from 1.3 to 2.5 hp (1 to 18 kW), discharge sizes from 2–6 in. and output flows from 36 m³/h to 324 m³/h.

In addition to the pump line’s patented Dura-Spin hydraulic system, other features include an impeller designed to prevent abrasive particles from reaching the impeller neck, a closed high-chrome cast iron impeller, and a one-piece plug-in seal that provides faster, simpler replacement. Its design also protects seal surfaces during disassembly and mounting. A single trimming screw allows fast and easy impeller trimming for optimal performance sustained over time. The line’s Spin-Out feature protects the outer seal and extends service life by expelling abrasive particles from the seal.

All pumps of this series can be equipped with a sacrificial anode for protection against bimetallic corrosion. Special voltages and modifications at extra cost are available upon request.

Flygt also offers the 2000 series with capacities up to 300 l/s. Eight pumps are available in two casing materials: lightweight aluminum, and durable cast iron for corrosive environments.

Tsurumi Expands European Market Selection
Tsurumi, following a two-year trial, is launching new dewatering pump models in the European market, including four LH models and the GSZ. The GSZ, designed for high-head, high capacity work in rugged conditions, is a three-phase submersible pump that stands almost 1.8-m tall, measures more than 1-m wide and weighs approximately 1.2 metric tons. The cast iron pump is capable of transporting up to 12,500 l/min with a maximum head of 52 m. It features a special steel impeller and suction plate to maximize working life, while an internal spiral structure ensures smooth passage of sand, soil, sludge or slime without clogging.  Its 4-pole motor increases durability, according to the company.

Tsurumi said it also has introduced its strongest pump cable to the European market. The rubber cable is durable and is designed to work with robust pumping equipment in
the quarrying and mining sector industries.

“In recent months there has been a noticeable rise in requests for pumps with strengthened cables that can withstand the hardships of modern construction and mining,” said Stefan Hörnschemeyer, marketing manager, Tsurumi Europe.

According to the company, rupturing a pump cable is the most common cause of pump equipment failure, particularly in quarries and mines, due to the rugged conditions, lack of visibility and presence of heavy machinery. Tsurumi said its NSSHÖU cable is designed for a long life in extreme conditions. It is suitable for very high mechanical stress and has a tensile strength of 15 N/mm2. It is well insulated and can withstand extreme heat and cold. The cable is ozone resistant, which stops the formation of cracks, and is bright yellow to improve visibility. It is available for both three-phase and single-phase pumps.

In the Australian market, Tsurumi has highlighted its presence by supplying hundreds of pumps needed to dewater mines flooded by the country’s torrential rainfall in 2010 and early 2011. Tsurumi distributor Australian Pump Industries said it had fast-tracked a million dollars’ worth of heavy duty construction-style dewatering pumps including deepwell slimline pumps with flows of up to 5,000 l/min and heads as high as 90 m.

Gorman-Rupp Unveils Infinity Line
Earlier this year, Gorman-Rupp introduced the Infinity line of submersible solids-handling pumps, which it said are built to the same standards of its well-known line of self-priming pumps. The Infinity line is available in 3-, 4-, 6-, and 8-in. flanged discharge sizes and ratings of 2–75 hp. These combinations will provide flows up to 3,100 gal/min (195.6 l/sec) and heads to 190 ft (57.9 m).

The pumps use NEMA Premium Efficiency motors and pass a minimum 3-in. spherical solid. A patent-pending eight-sided finned motor housing allows for optimal heat dissipation, extending motor life and eliminating the need for a cooling jacket. Pumps are available with channel or vortex impellers. The vortex models feature patent pending Staggerwing technology. Externally adjustable face clearances on channel impeller pumps improve efficiency without requiring time-consuming wear-ring replacement.

The company continues to offer its S series Slimline and Wide Base submersibles. The Wide Base models are designed for applications where high volume and high head are required, and large solids are not a problem. The pumps have only two moving parts and three wearing surfaces so maintenance and repairs are minimal, according to the company. The series encompasses 2- to 12-in. size models rated at 2–275 hp, with maximum capacity of 7,100 gal/min (448 l/sec) and heads up to 600 ft (183 m).

The Slimline models are lighter and easier to handle than the Wide Base units, available in sizes from 1.5-in. (37.5-mm) to 6-in. (150-mm) and 1- to 60-hp. Maximum capacity is 2,100 gal/min (133 l/sec) and heads up to 380 ft (116 m). Maximum solids handling capacity is 0.5 in. (12.5 mm).

Grundfos Covers the Submersible Spectrum
Denmark-based Grundfos offers a complete range of SP submersible dewatering pumps made entirely of high-grade stainless steel. Models are available with flow rates up to 475 m³/h. On request, rubber parts can be supplied in Vitonfi for handling contaminated water. Other features include state-of-the-art hydraulics, dry-running protection and remote monitoring.

The series features a complete range of high efficiency, canned submersible motors up to 30 kW (40 hp), and  rewindable motors up to 250 kW. All motors are available with optional motor temperature measurement for connection to a remote monitoring unit. All motors are available in warm-water versions and with SiC/SiC mechanical shaft seals.

Grundfos also offers the CU 3 electronic motor protection device for monitoring and protection of motors, cables and cable joints up to 400 A at 50/60 Hz. To ensure efficient and reliable dewatering, the CU 3 features a special dewatering function for automatic operation.