Open Cut » Overburden Removal
This report presents the results from the fast track version of the original ACARP project submission "Dragline Rigging and Control System for Universal Dig and Dump". The project was designed to investigate and quantify productivity data and machine loads, to assist in the assessment and retrofit design of a production dragline with the new operating system.
The "Universal" rigging and control system eliminates over two thirds of conventional dragline rigging. The bucket's carry angle is altered in the new system by attaching the hoist ropes, one to the front of the bucket and one to the rear, and differentially shortening one with respect to the other. The key to the system is the automatic control of the bucket's carry angle at any position and in any operational mode.
The Universal system was installed, fine tuned and tested on the CMTE 1/10th scale dragline, located at the University of Queensland. This fully operational dragline was instrumented with advanced data acquisition and control systems to allow the comparison between Universal and Conventional setups. Results from the 1/10th scale tests were analysed using a 1:250 scale dragline and sandpit to determine the overall changes in productivity for entire dragline excavation scenarios.
The results from these tests have shown that the increases in dragline productivity using the Universal system instead of Conventional rigging range from 18 % for a chop pass, to over 29 % for a conventional high wall pass. These values are based purely on the increased payload and decreased drag times exhibited by the Universal system.
The Universal hardware and software systems have proven their reliability on the 1/10th scale machine and are ready for prototype development. Data on dynamic and static machine loads have been gathered and can now be applied to full-scale retrofit design.
The tests have shown that there are definite changes in operational techniques required to maximise the performance of the Universal system. The training requirements to teach these new skills will require careful consideration, however the magnitude of the changes is small.
Several spin-off benefits of the Universal system have been identified and measured where possible. These include :
- Large reduction in number of rigging components required with the associated capital (approx. A$ 350,000 per year), and installation costs.
- Elimination of the lost time due to inspection and repairs on the rigging components in (1.) (between 0.5 % and 1.8 % of annual dig hours).
- Increase in available dumping height (approximately 5 m).
- Increase in chopping reach (approximately 3.3 m).
- Ability to dump material up to 40 m inside boom point. This will allow bench and bridge preparation to be far more efficient.
- Ability to limit the transient loads on the dragline by semi-automatic control of the operation.
It is recommended that further applied research and testing be undertaken to continue to improve the Universal system's performance using the CMTE 1/10th scale machine, and that the existing CMTE training facility be augmented to include training programs for dragline operators, engineers, supervisors and maintenance personnel, in all aspects of the new system.