Open Cut » Overburden Removal
This project was about the effective use of the dragline productive capacity. The dragline has a certain productive capacity which is made up of prime and rehandle. It is the prime, not the total, which dictates how much coal is uncovered.
While many millions of dollars have been spent increasing the efficiency of draglines with some excellent results, there are substantial losses in coal exposure being incurred through a lack of the effective use of the productive capacity. Operators are being judged against monitor output and this is directing their actions. The overriding requirement for the dragline is for the right spoil to be dug from the right place, dumped in the right location at the right time, to optimise the tonnes of coal being uncovered.
Many mines report a problem, "We are breaking all dragline production records but we are still short of budgeted coal and we don't know why." This is the problem this project addressed.
The objectives of the this project were:
· Specify the key linkage between planning and operations, ie the process for establishing a workable plan and following it;
· To align behaviours across the Operations, Maintenance and Planning functions by establishing procedures and systems for predicting and controlling what the dragline is doing; and
· Create a roadmap for the development of a systemic system for dragline planning and control using 3D planning, simulation technology, GPS and vision systems.
Linkage between planning and operations
Twelve mines with 38 draglines were surveyed from Queensland and new South Wales. There was a wide range of approaches to the effective execution of the planning - digging process. Some were clearly much better than others. The issues related to interaction between different aspects of the mining process were a major issue for some sites. The concept of complexity is a major issue for some pits with significant process delays occurring because the execution of the plan was not done effectively with resultant interactions between processes, eg. Prestrip and drilling for dragline strip, blasting and dragline, dragline and coaling, etc. The increase in these interactions appears to be a direct result of inadequate on-the-ground management / supervision. Planning ranged from none to 2D and 3D plans for all pits. Execution of these plans ranged from taking no notice of them to quite formal systems in place.
Dragline support tool (eCoach)
The investigation into this issue has demonstrated significant shortcomings in the expertise required to predict dragline performance and management over what the dragline is doing. This is primarily causing increases in process downtime and increases in "operational rehandle". The dragline is often at the end of the process tree and is impacted by a large number of processes which must occur before it can happen. This is particularly the case for multiple dragline passes.
Consequently a tool was specified which is the basis for implementing a form of supervisory control over the dragline. This tool has had a number of iterations and has been trialled at Bengalla Mine, Hunter Valley Mine and Mount Thorley Warkworth Mine. At the very least it provides some structure for the handover between crews. At present this tool is in the form of a paper-based hand-over sheet. It needs to be taken to the stage of being real-time and used on a personal communications device. This responds to the need for prioritised actions for supervisors to respond to as well as efficient prediction of what will happen in the next 12 hours , 24 hours and beyond. As an analogy, the Microsoft Outlook system allows for timetabling and warning of meetings; so to for the dragline the expectation of a walk or a cable move can be predicted, scheduled and reported on. Similarly, the reporting of a safety issue is immediate and universally known. The response should be swift regardless of what the responsible person is doing and wherever they are onsite.
The goal for future development must be the integration of the planning function with the operations function. Steps for future development are:
· Effectively capture of operations knowledge to incorporate into future simulation and planning; and
Automate the system so that plans, which are based on knowledge previously captured, are uploaded automatically from the simulator to the dragline. Changes to the plan are made automatically in response to what is happening in the pit.