Swedish mine modernises communications by unifying DMR and LTE

Zinkgruvan Mining AB is an underground mine in south-central Sweden owned and operated by Boliden AB, a Swedish metals mining company. It produces zinc, lead and copper concentrates, with the deepest level of the mine approximately 1400 m below the surface. In 2024, the mine produced between 75,000 and 85,000 tons of zinc and 4000 to 5000 tons of copper.

Across the mine site Zinkgruvan had an existing Tait DMR Express 20 two-way radio system with six radio sites and approximately 750 users, as well as a separate broadband 4G LTE communications system. The company wanted to integrate the two in order to create a combined solution allowing seamless voice calls between DMR radios and LTE devices, with LTE users integrated into existing talk groups. The ability to support private calls between radios and LTE devices was an absolute necessity.

The main problem however, was that the existing DMR radio system covered all areas of the mine, while the LTE system only provided coverage in one-third of the underground section. The majority of the mine staff work in areas with LTE coverage and were not keen on carrying two communications devices.

There was also a broader strategic driver: through the LTE system the company hoped to create a platform for further digitalisation, support autonomous vehicles and enhance automation — all key drivers to make the mine more efficient, safer and less costly to operate.

Tait proposed implementing its PTToX system, designed to interconnect narrowband two-way radio and cellular LTE broadband systems. The technology enables LTE devices to operate as PTT (push-to-talk) devices, allowing them to communicate with two-way radios. As a trial, a PTToX system was set up by Tait in the UK to demonstrate the effectiveness of the solution to Zinkgruvan. Tait then installed a gateway locally at the Zinkgruvan site to connect the PTToX platform, managed in the cloud from the UK, along with the existing DMR Tier 3 system at the mine.

The result was a system with no noticeable delays in communications between radios and LTE devices even though the PTToX installation is located off-site. The call diversion feature is proving very handy — calls to a radio user are forwarded to the LTE device when the radio is turned off, and calls to the LTE device are forwarded to the radio when the LTE device is out of coverage range. The Tait EnableFleet application also makes configuration changes and firmware upgrades easy to carry out remotely, with changes transferred instantly via over-the-air programming.

“Since we could use the same fleet management tools for both PTToX and legacy radio, administration was simple,” said Mats Andersson, Telecom Engineer at Zinkgruvan. “Administration of the PTToX devices was easy and straightforward.

“The main benefit is that the majority of our operators only need to carry one device. The call forwarding simplified operations and there was no need for re-learning users’ IDs and workgroups.”

Image: Zinkgruvan Mine: Credit: Boliden AB