Despite increases in safety, mining remains one of the most dangerous and hazardous sectors to work in - mostly because of the unpredictable and often confined areas in which operatives work.
One of the major concerns within the mining sector is the integrity of the tunnels and shafts themselves. Effective monitoring is vital to ensure the integrity of the mine and the safety of the workers. Comprehensive strata control and monitoring instruments form the backbone of your mining and tunnelling operation.
Rock-bolting has replaced standing supports such as steel arches in underground mining operations as the best method of supporting and controlling strata. Using this technique has led to significantly reduced costs, greatly increased productivity and considerably higher levels of safety. To support this technique of strata support and control it is necessary to monitor the strata for mine safety.
The new RockMonitor XR System takes monitoring on to an entirely new level. It continuously monitors the rock formations in a mine and it tells you whether they are moving or how they are changing in their structure and composition over time.
This allows operators to predict what is going to happen and more specifically they can forecast if there is going to be a rockfall or a dangerous incident.
This early warning capability gives operation managers the insight they need when it comes to deploying support structures or safety systems long before anything could go wrong and ensuring the safety of the workforce.
The current strategy is often to install mechanical telltale that are read visually, with the readings recorded sometimes with nothing more complicated than a pen and pad. With the new RockMonitor XR system the mechanical telltale is replaced by a remote reading version which can monitor up to four anchor points and convert the mechanical movement into electrical signals.
That signal is digitised and sent back to a control unit. Along any formation you can install up to 200 telltales, along seven kilometres of cable, which all feed back to one controller that refreshes every ten minutes. This is opposed to the manual system that will get updated probably at the end of each shift.
The technology utilised is linear variable displacement transducers (LVDT). As the anchor moves, it moves a metal rod inside of a coil. That changes inductance and then the PCB measures that change of inductance and converts it to displacement.
There are a variety of ways to measure displacement including sensitometers or optical versions, but we chose the LVDT because it is very low current, very low power and it is not susceptible to moisture and dust. That is vital given the environment that they operate in, which is nearly always dusty and humid.
In underground mines, certification approval is all based around low power or controlling power in a way that it cannot cause a spark in dangerous and hazardous environments. We don't have the option of utilising technologies that are power hungry, both because of the need for power, but also because of the hazards of high power in mines.
The RockMonitor XR meets these standards while providing continuous remote monitoring. With all this data logged and stored it allows ongoing data analysis and reporting while significantly reducing the need for manual data collection and input.
Overall, intelligent strata control greatly improves efficiency and safety by reducing the need to shut down mining operations for manual safety monitoring. It is also a boon for geotechnical engineers who are provided with continuous, highly-accurate data to aid mine design and development. This allows them to optimise support design that in turn leads to reduced cost.
With continuous remote monitoring of a longwall tailgate, operating efficiency can be increased significantly with up to 25 per cent up-time increase. When a mine-wide system is implemented, interfacing with the mine SCADA system, it can lead to typical savings of over $2m per year. But it is not all about increasing efficiency and reducing costs. Significant improvement in safety can be achieved when strata movement is monitored remotely rather than in-situ measurements taken by mine engineers.