Limestone Mine: Communication for Improved Safety & Process Efficiency

A large scale, privately owned U.S. limestone mine, was seeking a communications solution for improved process efficiency and increased safety. The mine runs three shifts in their underground operation with the capacity to produce millions of tons per year. They use automated machinery to produce a full line of limestone aggregates. During day-to-day operations, there were shortfalls in the quality and effectiveness of communications due to an antiquated repeater radio system, and the inherent inconvenience of stationary, hard-wired paging phones.


IWT was chosen to design and install a customized system accounting for:

  • High seam height
  • Coverage needed across 100 openings
  • Location tracking of miners and vehicles
  • Ease of access during emergency situations
  • Complex room and pillar mine with 50 working faces
  • Multiple teams running scaling operations cyclically across all faces
  • Continuous communication needed between personnel at the working face, mine office, and primary crusher
map of a communication and tracking deployment in a limestone mine

Figure 1, above, depicts a communication and tracking deployment in a limestone mine


The IWT wireless network provides voice communications, personnel and vehicle tracking, and includes integrated Wi-Fi capabilities.

SENTINEL™ Uniti Nodes are installed at all working faces and linked together using IWT’s High Data Rate technology.  HDR is a wireless protocol that provides fast, stable, and reliable connection between devices. Coverage of the working areas is provided by Integrated Mesh Nodes (IMN) and Battery Mesh Nodes (BMN), which offer specific RF solutions for active areas and the tall seam height typical in mines of this type.

IWT’s Phone Connect software, along with the SENTINEL™ Voice Bridge interfaced with Motorola’s protocol, was implemented to support enhanced communication from inside the mine. Combined with the Wi-Fi feature of SENTINEL™ Uniti Nodes’, this gives underground mine personnel the ability to use company-approved, third party smartphones and devices for communications via voice or video chat with other mine staff, as well as with vendors, support agents, and contacts outside of the mine network.

SENTINEL™ Uniti Nodes and SENTINEL™ Handsets with speaker mics were used as part of the solution for this limestone customer.


The SENTINEL system provides 24/7 communications between the underground workers and operations personnel on the surface. The improved communications increases both the personal safety of the miners, and the mine’s productivity.

The fully wireless coverage of working areas provides real time tracking location of miners and equipment for added safety and efficiency, especially in the event of a mine emergency.

Additionally, IWT’s High Data Rate capability enables integration with not only the customer’s existing industrial information, operations management, and industrial automation software, but also any new devices that utilize Wi-Fi functionality. This provides mine management a single interface for production-related data analytics and enables them to make operational decisions based on up to date information, allocate resources accordingly, and facilitate increases in productivity.