Open Cut » Overburden Removal
Dragline repositioning is a major source for the loss of productive dig hours. A trade off exists in any decision to remain digging at a particular location or to reposition the dragline in order to obtain more favourable dig conditions, spoil room or swing angles.
This project aimed to explore predictive applications of advanced dragline performance indices developed in project C20018 Advanced Dragline Analytics. In specific, it aimed to develop a predictive algorithm to provide dragline operators with advice as to how to improve dragline dig sequencing.
Using over 200,000 cycles of dragline performance data collected from DL 302 at Curragh mine during 2012, the project advanced:
· An automated block detection algorithm that uses threshold data limits to detect the start-of-dig position in an excavation block. This algorithm has the potential to be adapted and applied to generate performance summaries for dragline monitoring data collected over individual excavation blocks.
· An economic cost model that measures operating costs as a function of BCM-degrees considering equivalent swing angles. This enables upper and lower control limits to be established for equivalent swing angle charts. It also introduces a new unit of dragline work (BCM equivalent degree) that can be used to benchmark dragline performance.
· Equivalent swing angle charts, including box and whisker charts for benchmarking dragline swing performance in different excavation blocks and run charts to monitor the swing performance of draglines in different locations. The latter can be applied to determine dragline repositioning decisions in order to optimise dragline swing times and dig sequencing, thus enhancing dragline productivity.
· An algorithm for classifying the principal operational motives for repositioning a dragline. This algorithm uses a dig constraint matrix to determine moves due to lack of dig material, run charts of dump heights to determine moves based on lack of spoil room and run charts of equivalent swing angle to determine moves intended to optimize swing angles.
· Advanced dragline reports intended to convey information to dragline superintendents regarding production constraints. These constraints include hoist limited cycles and classification of the motives for dragline repositioning.
Following consultation with the project monitors, it was determined not to implement the dragline repositioning algorithm as an operator feedback tool. This was based on a recommendation to quantify the value of the enhanced reporting tools as management tools prior to implementing them for operator feedback.