Underground » Mining Technology and Production
This report describes the process and outcomes of a project that explored the development of a longwall creep control system. This project set out with an ambitious goal of developing an integrated closed loop control system to manage longwall creepage with the following objectives:
- Measure and model the relationship between longwall creep and lead-lag factors;
- Develop an algorithm to generate a recommended incremental steering correction profile suitable for integration into an existing LASC face alignment system;
- Stage a series of supervised creep control evaluations on a production longwall, ideally using automatically generated wedge cut profiles to demonstrate closed-loop control.
Creep control automation, in comparison with longwall face alignment and roof support automation, has seen virtually no systematic analysis and development over the past two decades. The project commenced with a formal review to determine the state of industry practice. It was found that the industry's readiness for creep automation was very low, with the current strategy for managing creep relying exclusively on manual observation and intervention and intuition, lacking critical formal measurement and modelling capabilities.
A set of prioritised monitoring requirements was identified to systematically guide new research activity in system characterisation, sensor technology development, and field validation. Starting from a low base, four underground evaluations were planned and conducted under full production conditions. Each evaluation progressively introduced new sensing capabilities which also involved accessing and processing the new longwall data to advance the understanding of creep dynamics and control.
Achievements in the first two project objectives include:
- Formal identification of the capabilities required, and identification of a technology development roadmap to achieve an automated creep control system;
- Advancement from manual to automated measurements of maingate creep and retreat by installation and validation of a laser-based sensor on the Beam Stage Loader (BSL);
- Comprehensive assessment of wedge cut events, lead/lag factor and creep over a sustained period, leading to new insights regarding the complexity of creep system dynamics; and
- Initial production testing involving partial and full wedge cuts in an open loop control mode.
Although the third objective to automatically generate closed-loop control was not able to be implemented, the project outcomes were accepted as being the limit of what was practically achievable based on the industry maturity levels, project scope and the realities of production conditions.