Open Cut » Drilling & Blasting
This project was developed to address the coal loss and dilution issues that are faced in open cut coal mining. An innovative Blast Hole Slotting System has been developed to reduce the significant amount of coal that is forfeited during the blasting and overburden removal process.
The aim of the project was to produce and test a prototype Blast Hole Slotting System that creates slots in overburden blast holes. This technology has the potential to reduce blast damage to an underlying coal seam by directing blast energy radially from the base of the holes, in a plane parallel to the seam.
This report presents the outcomes of Stage 2 project work, including a brief summary of the previously submitted Stage 1 report. It includes details of the development of a concept Slotting Tool and comparative blast testing of concrete blocks to assess blast performance.
Stage 2 received funding on the basis of the technology’s success during Stage 1. The objectives of Stage 2 were to:
- Design and construct a full-size slotting tool;
- Demonstrate and quantify the real benefits of slotting through full-size field trials; and
- Transfer the outcomes of the project back to the industry.
Manufacturing of equipment for a field trial of the system was completed in 2006. Commissioning of the system using a Test Well at CRCMining’s Pinjarra Hills site was completed in early 2007. A field testing program was proposed to slot and blast 4 holes within a small pattern on a mine site. Blast monitoring would to be used to assess the performance of the technology. This field trial was initially scheduled to take place at BMA’s Peak Downs Mine during 2006; however, it was delayed due to availability issues with CRCMining’s high-pressure water pump, CRCMining staffing changes and issues with field trial site availability.
CRCMining reported during a November 2006 ACARP Project meeting that additional funding would be required to complete the full-size field trial. This was caused by factors including inflation of supplier and manufacturing costs, skill shortage issues and unforeseen project delays. It was also established at this meeting that the scope of work for the field trial should be increased, incorporating slotting a larger number of blast holes and an improved post blast monitoring program to provide a more comprehensive and accurate assessment of the technology. This proposed increased scope of work has further impacted the funding required to complete the project.
A revised field trial plan was prepared by CRCMining in consultation with ACARP monitors, Peak Downs Mine personnel and blast consultant Andrew Scott. The new plan set a target of slotting 40–50 blast holes within a standard pre-strip pattern, with a minimum objective of slotting 20 holes. Detailed blast monitoring and post blast assessment would be carried out to quantify and compare the performance of the slotted and un-slotted sections of the pattern.
The Blast Hole Slotting System prototype produced during Stage 2 is functional and ready for field testing. CRCMining has submitted an Out of Round Proposal to ACARP to execute the proposed field trial plan. This proposal is currently (May 2007) under consideration by ACARP. The field trial of the system will require ACARP funding to proceed.
It is recommended that ACARP fund the full-size field trial proposed by CRCMining. This technology has had significant research, development and financial investment to date, and it is expected that the site testing will allow the potential of the technology to be demonstrated and its benefits to Industry better understood. A successful outcome would allow the Slotting technology to be recognised - and ultimately supported allowing commercial development - by industry as a practical and effective (if only partial) solution to a very significant coal industry problem.