Underground communications system improves mine safety

The problem

In the interests of mine safety and productivity, it is vital that operators are continuously aware of underground conditions and risk profiles. They must be able to locate and communicate with mine workers at all times - particularly in the event of fires, roof falls or other life-threatening situations.

It is equally critical that these communication systems stay active during power outages, fan stoppages or gas accumulations.

A CSIRO team visited more than eight underground coal mines to discuss the types of issues confronting surface Control Room operators. A number of common issues were identified including:

• the large variety of diverse and proprietary communication systems that were in use at each site
• large numbers of system-generated false and misleading alarms
• time delays in locating and contacting individuals
• a cumbersome manual statutory reporting system
• extreme workloads in emergency situations.

What CSIRO did

CSIRO, in collaboration with the Japan Coal Energy Centre (JCOAL), developed the Nexsys™ Real-time Risk Management System for underground mines. The system is comprised of:

• the Nexsys™ software package
• an electronic report-capturing system
• a suite of Ethernet-based, fibre optic and intrinsically safe (IECEx.ia) communications devices suitable for use in potentially explosive atmospheres.

Note: The International Electrotechnical Commission's IECEx scheme certifies equipment for use in explosive atmospheres, 'ia' is a further subset of the certification system.

Nexsys™ can source information directly from existing proprietary systems (Citect, Rockwell, Safegas and others), or connect directly to a variety of sensor networks.

It then integrates and interprets the data in accordance with a pre-determined set of rules and can autonomously initiate a response to breeches of these rules.

Information and real-time risk profiles are continuously displayed in two, three, and four dimensional formats anywhere on the mine's network, including underground stations and via handheld wireless units such as pocket PDAs.

The supporting (IECEx.ia) Intrinsically Safe hardware devices allow, for the first time in underground mines, some of the advantages surface-based industries have enjoyed for years - having broadband, integrated, Ethernet-based communication systems.

Using optical fibre and wireless access points, Nexsys™ brings the internet underground with all the interconnectivity, data sharing, video streaming and multiple-user advantages this technology provides.

These devices include:

• a five port, ten and/or 100 speed, multi-mode or single-mode fully managed Ethernet Switch
• a universal Serial to Ethernet Protocol Converter to connect any serial communication device or Programmable Logic Controller (PLC) to the Ethernet backbone
• an RF (Radio Frequency) bridge to connect a range of 433MHz and other wireless devices (personal and equipment location tags, chock and strata monitors etc) to the optical fibre network
• an IP56 electronic tablet capable of capturing, storing and transmitting copies of hand-written statutory and maintenance reports as they are being written. IP56 stands for International Protection standard for dust (5) and moisture (6).

An Ethernet-based two-way paging and locating system is under development that will allow the Nexsys™ system to autonomously locate and send text messages to personnel underground in response to a change in 'normal' circumstances.

These people will then be able to send text messages in response. The system has an interface similar to the familiar e-mail systems in use today and has similar functionality.

The outcome

Nexsys™ system's capabilities for information capture, integration and rules-based analysis, combined with new intrinsically safe communications hardware represents a major advance in the field of real-time risk management and productivity.

The Nexsys™ software system is currently undergoing field trials in:

• Anglo Coal's Grasstree mine in Central Queensland
• Xstrata's Beltana mine in NSW.

It has undergone trials at the Kushiro Coal Mine in Japan.

The IECEx.ia Ethernet devices are currently undergoing certification with Simtars.