Down Hole Drill Dust Extraction System

The objective of this project was to utilise wet bed scrubber technology, as opposed to existing dry bag systems to prevent fugitive dust entering the atmosphere during the down hole drilling process in Open Cut operations, by removing it at the source and preventing it becoming airborne.

A further objective identified as the project progressed, was the requirement to have "No visible dust" during the drilling operation at Mount Arthur North Coal Mine.

The objectives of the project have been met by the manufacture and installation of a wet bed dust extractor that removes as much visible dust as existing dust extraction systems. This performance is occurring despite the fact that system resistance created in the connection ducting is reducing performance by up to 80%.

Success can only be quantified subjectively as there is no measurement process in place to be used as a benchmark.

Project success has been based on opinions of dust collection from Mount Arthur Coal operations employees including:

• Senior Mining Engineers
• Senior Drill and Blast Engineers
• Open Cut Examiners
• Drill rig operators
• Maintenance personnel

It is the opinion of these people that the project Dust Extractor will have superior dust collecting capabilities to existing dust collectors and once the identified problems have been rectified, the unit will go closer to meeting existing requirements in relation to no visible dust.

The new dust extractor also offers benefits by eliminating fines from the dry dust extractor, is easier to service and is safer to service and maintain.

Several problems were experienced that have been addressed or need to be addressed to ensure the dust extractor performs to specifications.

Addressed Problems

1. The Dust Extraction system needed to be completely automated for all functions.
2. The water re-circulation system had to be converted to a total loss system to allow for the disposal of accumulated sludge in the tank and allow clean water to be pumped to the sprays.
3. The hydraulic supply had to be re-connected as it was incorrectly plumbed up in the first instance. This was identified by the lower than expected hydraulic pressure and flow and resulted in the system being overheated.

Problems Needing Addressing

1. Cleaning of the knitmesh panel has to be re designed to allow the reverse flush sprays to clean the panel more effectively. We have found that operators do not like to clean the screen on a shift-by-shift basis, as the accumulated sludge is messy to remove.
2. The drill shroud needs to be re-designed to allow maximum ground contact around the drill head. It was noted that the shroud has difficulty sealing when the hole is being collared, during periods of strong winds and when the drill rig is on a slope.
3. The connecting ducting from the shroud to the dust extractor needs to be re-designed to allow less system restrictions thus increasing flow into the unit.
4. The adaptor flange from the shroud ducting to the dust extractor needs to be re-designed to allow easier impeller changes and reduce frictional losses.

The objectives of the project have been achieved and with the above-identified problems addressed, the new Dust Extractor will ensure compliance to ever increasing environmental requirements for dust control.