Automated Hazardous-Substance Exposure Monitoring in Underground Mining

Recent advancements in sensor and wireless technology have created new and better ways to monitor short-term exposure limits (STEL) and long-term exposure limits (LTEL) for underground miners. Additionally, safety regulations in several countries are creating stricter and more robust requirements for monitoring environmental hazards and protecting underground workers from them.

This article will provide a brief overview of some high-level methods to advance your STEL and LTEL monitoring based on your mine’s broader technology infrastructure investment strategy.

The primary factors in evaluating the effectiveness of your exposure-limit monitoring strategy are accuracy of data collected and automation of measurements and alerts to reach real-time awareness.

Environmental Sensor Readings as Shown on  ConnectedWorker  ™ Vizualization

Environmental Sensor Readings as Shown on ConnectedWorker™ Vizualization

Semi-Automated Monitoring

The obvious way to track long-term exposure is to do periodic sampling of the environment and cross-reference with logs of workers' time spent underground. Depending on the mines processes this could be a manual endeavor. This approach is most commonly used to monitor against diesel particulate matter (DPM) in the Canada and US as well as coal dust in several countries. 

The challenge with long-term exposure monitoring comes from combining data sources which may be prone to human errors. Ideally, some sort of worker tracking system is involved to provide an error-reduced record of who was underground and when. In order of accuracy these historical logs can be derived from shift-schedules, tag-in/tag-out logs or Real-Time Location Service (RLTS) logs.

Some products, such as the Smart Tagboard, can automatically log time spent underground for each individual worker and export it into common programs such as Excel. Once in Excel, it can be cross-referenced with environment sample logs to determine personalized long-term exposure metrics. This semi-automated system can work well for many small-to-mid sized mines that lack capital to invest in an underground RTLS system.

Many RFID-gate systems used for RTLS can also export historical records of time-spent underground. However, these systems often come with significantly higher investment costs which are comparable to the installation of a wireless network.

Image depicts the scaling costs and abilities of exposure monitoring systems.

Image depicts the scaling costs and abilities of exposure monitoring systems.

Fully-Automated Monitoring

Fully-automated monitoring can be made possible by combining nearby environmental sensor data with worker location in real-time. This approach can be extremely effective at both STEL and LTEL monitoring. 

For mines planning underground Wi-Fi network investments for short-interval control and better communication, the most cost effective approach is to use open-standard environmental sensors and a modern RTLS system. 

Products such as ConnectedWorker™ Vizualization can then combine the two information sources into intuitive interfaces and to provide personalized STEL and LTEL alerts to underground operators, their supervisors, and safety managers.

Screenshot of  ConnectedWorker  ™ Vizualization  asset status page, showing the recent activity and environmental status of an underground worker.

Screenshot of ConnectedWorker™ Vizualization asset status page, showing the recent activity and environmental status of an underground worker.

More Information

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Do you know when your miners forget to tag-in?

In every underground mine there is a small human error taking place that has huge consequences. The problem with this error is that if it isn’t caught, the person who made the error almost certainly won’t confess to it voluntarily. Mines all over the world are not measuring how often this error takes place, despite them being Potentially Fatal Occurrences (PFOs).

The error in question is when someone from your operation forgets to tag-in before going underground.

Research done by Lifetime Reliability on human error rates sets the benchmark for the simplest possible task as 1 in 10,000. For a mine that has at least 100 people going underground every day, that means someone is probably forgetting to tag-in at your mine at least once every 100 days. It could be more frequent, especially at mines in developing countries where safety compliance is a greater challenge.

Despite how safe your culture is, it’s human nature to make a mistake from time to time. If safety is taken very seriously at your mine, then people may be afraid to report their error out of fear of disciplinary action. If you aren’t aware of this ever happening at your mine, then you may want to seriously consider the consequences if someone is missed underground without a tag on the board during an emergency.

Many mines these days have underground location tracking systems. They use these systems to see who is actually underground in real-time. Despite having these systems in place, every mine still uses a physical tag-board as a redundant safety process to ensure reconciliation of who is underground can still be done during a power outage.

The trick here is to use a smart tag-board that tracks tag placement digitally, and integrate it with your underground real-time location tracking system (RLTS). This way, if someone appears in the RLTS when they haven’t tagged-in yet, an alarm can go off and the incident can be resolved quickly and safely. Also, these incidents can be automatically recorded and measured.

By digitizing this core safety process, you will gain new KPI’s and ensure that when these mistakes happen they are caught immediately and safely, rather than turning into PFOs.