Currently installed on all underground vehicles at BHP Billiton coal mines in NSW, as well as mines owned by Xstrata Coal, Centennial Coal, Peabody Enrgy and Felix Resources, the externally fitted, disposable filters are made from polymer media and have an emission reduction rate of more than 90%.

Micro Fresh Filters business development manager Stephen Gledhill told International Longwall News the company has several new products currently being tested and hopes to provide a new series of filters to the market in coming months that will complement its industry standard DA100 filter.

Among them is a flat panel filter and different sized filters to cater for different mining vehicles. The aim - as with all underground mining equipment - is to minimise precious space taken up on the vehicle.

Micro Fresh engineers recently developed a compact filter cartridge for PJ Berriman to incorporate into its flameproof Mustang skid steer loaders. Dave Clinton of BHP's Dendrobium Colliery indicated that the filters last for a very long time and ensure that diesel particulate emissions are almost non-existent.

Gledhill said that while NSW legislation stipulates a cap on diesel emissions and requires filter canisters to be attached to most underground vehicles, some Queensland mines had introduced policies to have the filters fitted to their vehicles during longwall moves where diesel emissions can be at their highest.

"We're working with most of the mining companies to reduce diesel emissions at their site through various controls, but we believe far and away the best course of action is to have the filters fitted to the exhausts of all diesel vehicles," Gledhill said.

"This is further evidenced by BHPB having made our filters mandatory on most vehicles for 10 years.

"A detailed investigation culminated in BHPB's initially internal - but now industry accepted - training manual, Diesel Emissions Management.

"This found that one of the most effective methods of reducing DPM emissions to the internationally recognised safe exposure limit of 0.2mg/m^3 was through the use of our exhaust filters."

He said the company's flame resistant media puts Micro Fresh's filters ahead of other products on the market that have had troubles with fires, something that can not be risked in volatile underground coal mines.

The exclusive polymer media technology shows no sign of ignition until it reaches over 900C. It also has a better ability to cope with water carried over from water bath scrubbers resulting in lower back-pressures, longer filter life and less chance of a blow-out.

"What we're finding is that even companies that aren't required to meet the MDG29 guidelines announced by the NSW Government are working with us to reduce their diesel emissions and have been really happy with the product," Gledhill said.

"Two OEMs are currently externally testing new filter products for new engine packages at Diesel Test Australia, Londonderry - that we're hoping to introduce into the market soon.

"Numerous other filters are being tested by Coal Mines Technical Services, which we hope to have results from early in the new year."

For now though, Micro Fresh anticipates an increase in demand for its products as the requirements of MDG29 come into force and has recently branched out into the automotive sector after acquiring Ausc Filters, a brand that specialises in air, oil and fuel filtration.

"Ausc Filter products will be branded under Micro Fresh Automotive, effectively expanding our interests across all industrial vehicles, with a product range to cover light vehicles through to heavy-duty mine equipment," Micro Fresh managing director Ray De Jersey said.

"The new range is also in keeping with our emission reduction philosophy.

"Effective engine system (air intake, oil and fuel) filtration reduces emissions before they need to be filtered from the exhaust. In the high-dust mining environment (opencut and underground), regular engine system filter replacement should be a main priority of diesel mechanics."

De Jersey said acquiring the company was a natural progression after Micro Fresh had established that Ausc Filters' products met with its strict quality requirements, all having full certification and warranty.

"With an economical range of premium filters, minesites can now ensure that engine filtration systems run at their optimum by replacing filters before their performance degrades, but at no additional cost," De Jersey said.

"This results in engines that run better and produce fewer emissions."

Gledhill added that Micro Fresh stands by the performance of its Diesel Exhaust and Engine System filter products for mining environments.

"We have the support of various sections of most major mining groups; they trust our products because they know our products are of the highest quality and will not fail," Gledhill said.

"We are willing to provide technical and management support and in some instances fund trials for those wishing to adopt Micro Fresh filtration solutions."