Open Cut » Drilling & Blasting
This report documents the outcomes of Phase 3 of this project and builds upon the developments of Phase 2 and project C23029. These series of projects have focussed on the development of novel mining explosives using hydrogen peroxide (HP) that have the potential to eliminate Nitrogen Oxide (NOx) fume emissions from blasting. The toxicity of NOx and its impact on licence to operate issues have been extensively reported. ACARP has been proactive in looking for long-term solutions to address this hazard. Following from key recommendations outlined in the final report of Phase 2 (C25005), the principal objective of Phase 3 was to consolidate all research efforts to demonstrate the on-bench delivery of product and conduct rock blasting with multiple blastholes at a much larger scale than previously attempted. Originally, the blasting trial milestone envisaged a test at an active mine with 2 to 3 large diameter blastholes (ie 200mm - 270mm).
Due to a number of issues, the blasting trial was re-designed and conducted at a quarry located near Gore, Queensland. This is a Limestone quarry owned by Southern Queensland Lime. The trial implementation process included the following tasks which are discussed in detail in this report:
- Selection of the HP formulation and sensitisation for trials;
- Compatibility of the HP product with blasting accessories (booster and detonators);
- Compatibility of Extech unit to load products;
- Pumping of product using the Extech unit;
- QA/QC and preliminary testing of the HP product; and
- Final loading, blasting and monitoring of results.
In addition to the trial implementation, the early stages of the research program in this phase of project C25005 (phase 3) included the design improvement, construction and demonstration of a prototype system that could manufacture the HP gel (precursor) in larger quantities so that larger scale trials could be attempted. This element is also documented in this report, including the main components of the system and operating procedures.
- Design, construction and commissioning of an improved prototype HP based Gel manufacturing system capable of producing 500 kg of product delivered at ~75kg/min. The unit was successfully tested at the Pinjarra Hills facility using a dummy product.
- Operational procedures were developed for future applications of the unit, however a number of potential hazards/concerns were identified during the commissioning of the prototype plant and these are thoroughly detailed in this report.
- Fulfilling the last milestone, a quarry scale multiple hole blasting test using HP based products was successfully designed and implemented. Blastholes were loaded in each row with an HP based mixture sensitised with chemical gassing, GMB and EPS. The blast was instrumented with triaxial surface mounted geophones; a high-speed video camera and three lines of VOD monitors. Performance monitoring and diagnostics indicated that the blast was considered very successful with no evidence of misfires; rock mass displacement and fragmentation consistent with expectations.