A number of new iron ore deposits are being developed at the operation to sustain mine production. These deposits lie in close proximity to existing site facilities with some blast areas just 30m from major infrastructure. The sensitive environment meant blasts had to comply with strict vibration and flyrock limitations while adhering to a tight schedule and blast window to minimise delays and disruptions to the operation.
To meet the deliverables of the operation, drill and blast contractor JSW Drilling developed and applied a progressive and detailed methodology to the blast design, execution and evaluation. The process encompassed: advanced 3D modelling and design of the areas; advanced vibration prediction algorithms to predict vibration for every individual hole based on its specific charge weight and distance; detailed timing initiation plans including focus around vibration frequency control; utilisation of electronic detonators to allow one millisecond timing interval control and advanced single hole firing capability; a detailed evaluation of each blast result, including analysis of vibration PPV results and waveforms; and the development of site-specific vibration laws based on the collected data and analysis of vibration PPV and waveforms.
Warren Fair JSW Drilling CEO said: "Generally it is acceptable that you would just use the maximum instantaneous charge hole and the distance from this to the infrastructure to predict vibration. Our methodology is far more detailed and provides greater accuracy by running vibration predictions on every hole on every blast rather than just the once for each blast."
Industry-leading quality assurance comprised an iterative programme and monitoring procedure to continuously improve blast outcomes including vibration results. "The constant feedback cycle resulted in improved vibration frequencies and minimised the potential of damaging frequencies," Fair said.
This precision allowed all blasts to be successfully undertaken with no flyrock ejection, no damage to infrastructure or delay to operations.
A total of 120 blasts all subjected to JSW's quality and HSET management system resulted in total material movement of circa 750,000 bank cubic metres.
JSW continues to deploy the approach, applying ongoing evaluation and improvements at all its applicable drill and blast projects.
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