Open Cut » Health and Safety
Following the findings from project ACARP #C17034 into dust control on dragline machine houses, a cartridge filtration concept similar to the AirScrubPro" system in use on the P&H 4100 XPB/C shovels was identified as a potential solution to explore in the development of alternative dragline machine house ventilation and dust control technologies.
From a single set of pressure and flow measurements taken on an AirScrubPro" system it was concluded that there would likely be some resistance by the industry to implementing cartridge filtration technology on draglines unless the overall system pressure drop for the cartridge system could be reduced somewhat and the overall weight of the system could be reduced to about the weight of the current Dynavane based filtration systems.
Consequently, the original focus of this project was to identify whether an alternative cartridge filter construction could be developed with improved flow and pressure drop characteristics compared to the filters normally supplied for use in the P&H AirScrubPro" system; and assuming a set of filters having improved characteristics could be made to the same dimensions as the existing filters, to arrange for such filters to be installed on an operating shovel and field test the new filter design.
On completion of the first stage of laboratory testing of a standard cartridge, it became apparent that the performance of the standard filter cartridge as tested in the clean condition was very good and the advice received from the potential alternative filter manufacturer was that it would be difficult to develop a new filter cartridge design that would achieve a significantly reduced pressure loss simply by changing the filter medium.
Subsequent to this advice, the direction of the project changed to one of verifying how the pressure drop across the filters actually varies with time in service and how well the pulse cleaning appears to work in extending the usable life of the filters on an operating system. BMT WBM installed test equipment to continually monitor various pressures on a P&H shovel operating at Rolleston and from these measurements has made deductions as to how the filters tend to behave in service. In the light of the various findings relating to where the bulk of the pressure drop is likely to occur with cartridge filters, BMT WBM has revised one of the preferred cartridge filter concepts for implementation on a dragline so as to incorporate a circular to square expansion diffuser to achieve pressure recovery at the discharge of the cartridge filters rather than attempt to achieve improvements by way of changes to the cartridges themselves. This latest concept also incorporates a simplified dust extraction/scavenge arrangement that allows the system to be mounted just above roof level, eliminating the need for extensive walkways and support structure that made the previous concept considerably heavier than existing filtration systems.
An e-newsletter has also been published for this project, highlighting its significance for the industry.