Work output in a potash mine requires machines with high mobility and reliability. Potash is a salt containing a high concentration of water-soluble potassium, so it is widely used in fertilizer. In response to the world’s increased demand for potash, Canada’s PotashCorp., Saskatoon, SK (PCS) stepped up production at its Rocanville, SK mining facility with an X CEL 44 continuous bore mining machine.

The X CEL 44 series miner, built by Prairie Machine & Parts Mfg., Ltd., Saskatoon, weighs in at 250 tons and can extract up to 1200 tons of potash per hr. The machine PCS had been using was propelled by a pair of fixed-speed hydraulic motors.  This was great when the machine had to plod along collecting potash. However, when it had finished mining one area, and had to move to the next work site, it moved at the same snail’s pace. This robbed productivity because the machine produced no output while it was in transit. Mine operators wanted to speed things up, so HyPower Systems Inc., Regina, SK, stepped in.

Application challenges

PCS has relied on Eaton distributor HyPower Systems Inc. to provide hydraulic components and expertise for its mining machinery. When the need for an additional miner became evident, PCS asked HyPower to redesign hydraulic circuitry of the machine and to work with Prairie Machine on fit, functionality, and integration requirements.

Delving into the project, HyPower’s engineering team called on Lyle Meyer, Hydrokraft product manager at Eaton Hydraulics, Eden Prairie, Minn., for a two-speed hydraulic motor recommendation.

The solution had to fit into a tight envelope in the miner. The biggest challenge, though, was that the motors needed to default to maximum displacement if hydraulic system pilot pressure was lost. This is in contrast to a standard motor, which defaults to minimum displacement with no pilot pressure.

A speedy solution

Meyer recommended Eaton’s two-speed Hydrokraft motors after confirming with Eaton’s manufacturing facility inWehrheim, Germany, that the motors could be made to default to maximum displacement. HyPower specialists specified a pair custom 250-cc Hydrokraft motors into the miner’s hydraulic system design proposal, which also included Eaton DG4S4 valves, V Series vane pumps, and a Series 2 piston pump to operate auxiliary functions.

The DG4S4 soft-shift directional valve features adjustable shifting time of the spool to control flow acceleration and deceleration ramping, which provides smoother cylinder starting and stopping by preventing hydraulic shock.Benefits include longer machine life, higher machine safety, and improved machine reliability.

The VMQ Vane pump has a hydraulically balanced removable cartridge with double-lip vane design. These features provide quiet operation and high pressure capability while maintaining high efficiency. And as is typical of vane pumps, they feature high power density, and removable vane cartridges reduce maintenance costs.

PCS accepted the proposal and endorsed the design of the miner’s hydraulic system using the custom Eaton Hydrokraft motors.

Results

Following retrofitting and testing of an existing mining machine, it was completely disassembled in order to be transported down shaft to the mining site. Simultaneous with these projects was the task of carving out rock 3200 ft below the Saskatchewan prairie in order to build a shop to reassemble the 38-ft long by 22-ft wide miner piece by piece. Because hydraulic redesign increased travel speed by 40%, the multi-million-dollar investment has been paying off for PCS since the machine was recomissioned in November 2009.

The increased tram speed saves two hours of tram time and more, says PCS’s Cecil Huber, general maintenance foreman underground. “The time savings frees up the operator to help with setup sooner and allows us to move the electrical set that much sooner as well,” Huber revealed. “Eaton’s Hydrokraft motors give us twice the drive torque to the tracks, which results in better control. Tram pressures are lower, resulting in lower operating temperatures in the hydraulic system.”

Not surprisingly, PCS has begun adding five more X CEL miners equipped with Eaton Hydrokraft motors, DG4S4 soft-shift valves, and VQM vane pumps to its Rocanville machinery lineup.

Contact Information:
Lyle Meyer, Eaton’s Hydraulics Group (952) 294-7936,
LyleGMeyer@eaton.com