Can fire-resistant hydraulic fluids be effectively used in potash mines?

CAN fIRE-RESISTANT hYDRAulIC fluIDS bE EffECTIvElY uSEDIN POTASh MINES?

By shaunti Bergen

the following is an overview of research completed by engineer Shaunti Bergen for her master’s degree in mechanical engineering, completed at the University of Saskatchewan in 2021.

the problem

Hydraulic fluid power is commonly used in Saskatchewan’s underground potash mines in equipment such as roof-bolters, earthmovers, and borers. The reliability of this equipment is extremely important because shutdowns are not only costly, the location of the equipment means it isn’t easy to access for maintenance and repairs.

Potash dust formed during the mining process affects the reliability of the equipment; the dust is commonly found as contaminant inside the hydraulic systems. Conventional mineral oil is currently used in the underground equipment as it is acceptably reliable in this unique environment. underground machinery.

However, the risk of fire due to the flammability of mineral oil has raised the question of whether fire-resistant hydraulic fluid can be used successfully in underground potash mines instead of the mineral oil.

Hydraulic systems can start fires by a leak in the circuit, spraying atomized fluid onto the hot surface of the equipment. The atomizing of the mineral oil decreases its flashpoint, causing it to burst into flames immediately. In most cases, the fire continues to burn as the leak provides a continuous supply of fuel, causing substantial equipment damage.

exploring fire-resistant hydraulic fluids

The safest hydraulic systems are ones that prevent dangerous events from ever occurring. Regular maintenance of hydraulic circuits can reduce the risk of hydraulic leaks, but removing the risk of a fire developing is always the best safety measure. Fire-resistant hydraulic fluids have a higher flashpoint and the ability to self-extinguish. This means if a hydraulic spray is atomized, the fluid will have a difficult time catching fire on the hot surface and even if it does, the continuous spray will extinguish the fire instead of fuelling it.

Fire-resistant hydraulic fluids are also safer environmentally, preventing time-consuming and costly clean-ups. Prior to testing, a fire-resistant hydraulic fluid’s only flaw was that there was no proof it could perform reliably in an underground potash mine, whereas the currently used mineral fluid has worked reliably since the 1960s. Being able to use a fire-resistant hydraulic fluid in underground potash mines would be advantageous, but testing was needed to ensure it could perform.

how the fire-resistant hydraulic fluids were tested

Testing was conducted by taking three fire-resistant hydraulic fluids and running them against the currently used mineral fluid. The test bench had four

identical hydraulic circuits to do this, each with a 18cc axial piston pump, which was used to measure wear. Each

test was run for 200 hours and electro-proportional valves caused cyclic loading between pressure compensated cut-off, full flow and standby