Published in March 2008 Australian Longwall Magazine

Industrial filter specialist Micro Fresh was chosen by the companies as the preferred supplier for the Coaltram’s exhaust filtration, primarily because of its new filter design which takes the form of a panel rather than the traditional cylindrical design.

The twin filter panels separated by an integrated centre cavity allow the filter/housing to be much smaller than cylindrical counterparts. There is the same amount of filter media in one Coaltram exhaust filter as there is in two of the previous DA100 cylindrical exhaust filters.

This has been achieved through the use of deeper pleats that safely trap collected particulate deep within the filtration panels. This centre cavity/dual panel design therefore ensures that any risk of operator exposure to diesel particulate matter (DPM) is minimised during changeout procedures.

Micro Fresh said the Coaltrams have actually been designed to take these new filters, and a storage cavity has been incorporated into the machines to store a spare exhaust filter and carry used filters, allowing for fast underground changeover if required.

Micro Fresh business development manager Stephen Gledhill said the filter media is an advanced co-polymer that was developed exclusively for Micro Fresh by the 3M Corporation.

He said the co-polymer was designed specifically to overcome the inadequacies of paper and fibreglass exhaust filters that have been used by original equipment manufacturers in the past.

“The primary favourable attribute of the co-polymer media over paper is that when tested, it shows no sign of ignition at 900 degrees Celsius, simply melting if subjected to above average temperatures. This is of vital importance given the presence of methane within underground coal mines,” Gledhill said.

He said that furthermore, the co-polymer media has a better ability to cope with incident moisture carryover from exhaust cooling (wet scrubber systems).

“The media will not degrade and due to combined mechanical and/or electrostatic filtration properties results in lower back pressure on the engine and exhaust system. The media can also hold significantly more particulate before changeout is required, resulting in longer operational life,” Gledhill said.