Remote monitoring of the condition and location of equipment and workers is an integral part of mine automation and control, but in any efficient operation it is important to know the activities on important assets. Maurice Jones reports.
If the mines and equipment are working in isolated areas it becomes even more important, for safety and rescue reasons, for the mine controller and management to be aware of unusual occurrences. This article concentrates on monitoring equipment rather than geotechnical, environmental and personnel matters.
In addition to ‘breakdown’ warning, regular monitoring of machine condition can provide valuable data for the planning of plant replacement and the best allocation of maintenance resources. The data can even be collected and analysed at a centre remote from the mine itself, perhaps with the assistance of the equipment manufacture as part of a service contract.
Trolex’s approach is to combine machine conditioning monitoring with its more traditional gas monitoring, the latter obviously having an effect on whether machines can operate in potentially hazardous atmospheres. Both fixed and mobile applications are covered. The company’s remote monitoring systems not only on collects data maintenance and performance issues, but Trolex is also working on clearer figures on how it produces a demonstrable cost saving through improved productivity.
For example, it is estimated that the Trolex Commander monitoring longwall coalface electrical gear has produced a 20 per cent improvement in productivity by data collection from motor starter gears. The aim is to keep coal cutters working continuously.
Typical sensors, protected against harsh environments, include those for vibration (to indicate deteriorating bearings), temperature and pressure (oil loss etc.). These are matched to audio and visual alarms both on the machine and for remote warning.
The efficiency of remote monitoring methods depend heavily on the type of communications used by the whole mine and whether the monitoring is active or passive. The wider installation of fibre-optic systems has increased the reliability of personal monitoring, largely because it eliminates many problems associated with radio signal transmission underground.
The MineWatch range from Davis Derby incorporates equipment monitoring with control and communications for hazardous atmospheres. The system is flexible with three modules to work with conveyors, pumps, fans, etc. as well as environmental duties. The modules can be reprogrammed on site and the plc ‘ladder logic’ software is user programmable.
The remote ‘health’ monitoring of key plant such as conveyors, main crushers and shovels in surface mining is equally important although, of course, communication becomes much easier. P&H’s PreVail system addresses the problems of increasing plant complexity, and trouble-spot identification, to increase reliability of production.
The on-board data logger collects data from strategically located sensors, and incorporates pre-set alarms for conditions of concern. The date is transmitted by radio to both the mine network (for alarms, etc) and to P&H’s server via the internet.
The PreVail application server analyses data to determine trends and so warn of probable maintenance problems in advance. P&H claims that use of PreVail remote health monitoring can reduce face shovel downtime for an unexpected event (eg, dipper drop) from one to three days to only six hours due mainly to easier identification of the cause of the problem.
Similar remote health monitoring systems are offered by other manufacturers of key plant such as Atlas Copco for drill rigs
Video: Introduction to the PreVail RHM (Remote Health Monitoring) for face shovels etc. by P&H (Joy Global Surface Mining)