Accurate survey of the rock face and measurements of borehole deviation to detect and calculate blasthole burden is crucial in drill and blast operation. The benefits include reduced explosive cost, and fly rock control, better yields and fragmentation.
Poor face assessment errors can lead to poor yield, waste explosives and prolonged drilling times. The common face profiling assessment errors are the under and overestimation of the face burden and face height.
The size of the rock pieces depends on the use to which the rock product is to be put, eg large stones for coastal armour or small stones for grinding to dust used in cement. To precisely survey the rock face, it is imperative to determine the rock mass and the explosive energy needed to achieve objectives. Often geometrical errors occur in blast design because of incorrect face assessment and drill errors.
The key to precision blasting is to know the amount of rock or burden in front of each drill hole to be charged with explosives. Armed with this information the engineer can optimise the ratios of explosive energy to rock.
To address changes in regulations and growing concern for blast geometry measurement, Austech use industry the standard reflectorless 3D laser scanner. This can then be used for 3D rockface profiling to determine rockface geometry, blasthole burdens and 3D mapping of entire mapping of the quarry sites. Together with the scanner we utilise the non-magnetic borehole deviation technology-Boretrak System. The Boretak system calculates the borehole deviation from the design at fixed intervals using inclinometer sensors to enable us to quickly and safely survey the blast holes “as-drilled” for blast design and audit purposes.
The data from the laser scanner, together with the borehole deviation measurements, gives a comprehensive overview of the area of rock face to be blasted.