Open Cut » Overburden Removal
This report presents a method for measuring the in-bucket material volume on a dragline for the purpose of estimating the material's bulk density in real-time. Knowledge of the blasted overburden bulk density can provide instant feedback to mine planning and scheduling, enabling better dragline bucket selection and improved blast design. Furthermore, dragline operational costs and maintenance can be reduced. The real time estimation of bulk density is a fundamental component in advanced production and performance sensing technology.
CRCMining has successfully installed and trialled a proof-of-concept bulk density measurement system on a BE1370W dragline located at Anglo American's Drayton Mine in NSW. The system works by collecting a set of 2D laser scans of the bucket and extrapolating them to produce a 3D profile of the bucket. The system calculates in-bucket material volume by comparing the profile of a loaded bucket against an empty bucket. Bulk Density is subsequently determined from this calculated volume and the payload weight available from the existing dragline monitor.
The system has measured in-bucket overburden volume to an accuracy of greater than 95% for 22 buckets in a calibration trial. Following these trials, the system measured a further 1500 buckets under various operational conditions over multiple shifts. The bulk density estimation system does not interrupt dragline operation and provides an instant measurement for each bucket.
The system is also able to map bulk density across the dig areas. Mapping of the in-bucket bulk density (or fill factor) to original dig positions can be performed using rope lengths and dragline encoder positions provided by onboard systems in conjunction with a GPS and Orientation Sensor. We show spatial and time-varying bulk density, volume, and fill factor distributions over multiple shifts and multiple months.