Where it began…

Although mining is an industry with a long history, communication technology systems in underground mining are a relatively new addition to the industry. Only in the twentieth century did mining communication systems begin to appear in underground mines, with Western Electric standard telephones popping up in 1913. The only essential difference between these phones and standard telephones used above the ground was that the ones used in underground areas were enclosed in cast-iron boxes to protect the instrument from exposure to moisture, acid fumes and gases.

The early years: requirements for underground mining communication systems

In the 1970’s design and development of modern communication systems for underground mining operations was prioritized in order to break away from the primary focus on the telephone set. The US government identified a set of requirements to further research and development:

  1. Communication devices must meet intrinsic safety standards. This applied to coal mines as well as other explosive environments.
  2. Communication systems must be compatible with the specific environment and its needs – able to withstand dust, moisture and corrosive conditions.
  3. Devices and infrastructure of systems must be rugged in structure – able to withstand maintenance by 10-inch pliers and 4-pound hammers, as well as impact from roof collapses.
  4. Infrastructure must be flexible in terms of size to allow adaptation to the needs of both small operators and large companies.
  5. Communication systems must be designed as an integrated system where all devices, cables, power supplies and station sets are intrinsically safe.
  6. New systems must be compatible with the telephone system in use at the time in order to seamlessly integrate with aboveground communication instead of being the single cause of change of aboveground communications.
  7. Value-added pricing: the systems must be affordable and must enable savings in operations in order to offset the cost of installation.
  8. Full-service full-support concept: communication systems must be packaged along with a service offering that provides for maintenance, training (initial and continued), route design and transmission engineering.

Underground mining communication requirements Today

Not surprisingly current day (United States) legislation regarding the requirements of two-way communication systems is significantly broader and yet more detailed. While mine-specific circumstances must be considered in determining the appropriate specifications for two-way communication, MSHA provides the following outline as guidance for mine operators to best approximate the functional utility and safety protections for meeting the intent of emergency operations:

General Considerations

Any post-accident communication system should make untethered devices readily available to miners for communicating with the surface; should provide either voice or text two-way communication; provide an audible, visual and/or vibrating alarm to alert of incoming messages; should be capable of sending emergency messages to each device; should be capable of providing communication between untethered devices; should be installed to prevent interference with other transmission signals such as blasting circuits.

Coverage area

The system must provide coverage throughout all working sections in a mine, along escapeways, as well as coverage zones inby and outby strategic areas of the mine; when assigned to work in bleeders or other remote areas of the mine that are not covered with the communication system, miners should follow an established check-in/check-out procedure; communication must extend to refuges.

Permissibility

Communication systems must be approved by MSHA under all applicable policies such as 30 C.F.R. part 23.

Standby power for underground components and devices

Both stationary components of infrastructure as well as untethered devices must have a standby power sources with a capability of providing sufficient power for the duration of evacuation and rescue procedures in the case of power failure.

Surface component considerations

The surface component of the system should include a line-powered surface device with standby power; the communication system should be configured to allow communication between underground personnel and the communication centre; the communication centre must be operated by a responsible and trained person, always on duty, who is capable of handling income messages and responding immediately in emergency situations; although communication systems can be monitored from a remote site, the mine must have full system capability at all times; the surface portion of the system has to be equipped to print communication reports, message histories and other system data.

Survivability

Post-accident communication systems should be provided with redundancy protocol to ensure continued communication between underground and surface components even during disruptions and system malfunctions; system components located in areas that are at risk of damage should be outfitted with extra protection.

Maintenance

Equipment manufacturers must package communication systems with a service offering that provides a maintenance schedule and checklist to the mine operator.

Mining communication innovations

Development of communication technologies such as WiFi networks that are tailor made for rugged underground mining environments provide operators with an abundance of options for complying with regulations, such as Mobile Voice Communications based around VoWiFi technology, Duress alarms and Text messaging via personal Android handsets.

To read more about the WiFi techology designed to improve safety and communications in underground mining environments, download your FREE copy of our ‘Mine Safety 101’ eBook now!

Underground Mine Safety