The blasting expertise of BME’s AXXIS™ Product Support and Global Blasting Technical Services (GBTS), together with the drill and blast team at an open-cut metallurgical coal mine, successfully implemented complex pit design changes. This collaboration enabled the adoption of a more efficient blasting method, significantly enhancing operational efficiency.
This project was essential to overcome the limitations on excavation caused by the previous bench design philosophy implemented. Difficult geology in the lower 20m of the blast bench also contributed to poor fragmentation results, which further impeded performance.
By integrating production benches across multiple pits and increasing the blasted depth from 24m to 48m, the mine has significantly reduced both costs and cycle times. These improvements stem from faster overburden removal using excavators and haul trucks, streamlining the overall extraction process.
“The mine has since reduced downtime due to inefficient blasting and achieved the desired fragmentation which, together with optimised load and haul operations, has increased overall productivity,” said BME’s General Manager of Marketing and Technology, Nishen Hariparsad.
Hariparsad said that the project posed a number of challenges, including the need to maintain optimal fragmentation and blast performance when integrating the benches.
“A poor result could have resulted in a large area that would be difficult to excavate – which would require costly remediation,” he explained.
BME’s GBTS team and AXXIS™ Product Support and the mine’s drill and blast team also had to work around limiting pre-existing conditions. While the mine already had a sound drill and blast process, the face of the lower bench could not be drilled due to the original bench design and high wall standoff. “As such, we had to adopt a different blast style,” he said.
During the planning phase, the amount and use of explosive energy – as well as how these would be impacted by initiation – was carefully considered.
“Blast area size and rock response time were also important factors as these would ensure that adequate burden relief was introduced to facilitate blast movement and secondary fragmentation,” said Hariparsad.
He said that an innovative blast initiation sequence was designed to activate two central lift points within the blast zone, thereby creating relief by incrementally increasing the timing from these points.
“Ensuring sufficient timing was of utmost importance to effectively blast rock so as to maintain the desired fragmentation,” he elaborated.
BME’s AXXIS™ digital initiation system was critical to ensure the high accuracy required to undertake the blast. The flexibility of the AXXIS™ system enabled the calculated initiation timing to be programmed down to sub-millisecond accuracy, providing absolute control. He said that the timing was designed in elliptical form to facilitate favourable surface movement under given conditions.
“The blast was then simulated using BME’s BLASTMAP™ software, an enabling tool of the AXXIS™ digital initiation system. In this way, we were able to commit predictable outcomes before actual detonation,” he explained.
To ensure that the correct blast design was implemented, the rock geology was assessed ahead of time. He added that explosive type, strength and loading for each hole were also considered and the powder factor adjusted around the central initiation points to ensure that there was sufficient energy to create relief within the blast.
As anticipated, the blast design achieved the desired fragmentation at deeper levels, which was previously a key concern considering its potential impact on performance.
“Based on the success of this blast, the mine has continued to use this method to merge benches and the new mining approach,” concluded Hariparsad. “This positive project outcome has enabled our customers to work towards achieving their goal of establishing a new benchmark for coal mining productivity and efficiency, further showcasing how BME’s AXXIS™ system delivers predictable outcomes.”
