Effective monitoring of vibrations of the quarry – Boliden leads the way

Ore mining has been a major industry in Sweden for centuries. Present day mining is concentrated at a few large mines with highly streamlined operations. The country’s largest mining company, Boliden, owns the Aitik mine, which is Europe’s largest copper mine and one of the largest open-pit mines. Effective vibration measurements are a prerequisite for fulfilling government environmental requirements. Measurement is also an important tool for Boliden to help them to further develop their blasting technology.

The Aitik mine conducts 6 to 8 blasts every month, which frees 500 to 600 tons of ore, approximately 1 ton per hole. The mining activities affect about 100 buildings in four surrounding villages located within
3 to 8 kilometres of the mine. The strength of the vibrations and pressure waves vary not only because of the distance to the edge of the mine, but also because of how the bedrock is constituted in different directions, how deep into the mine crater the blast is, and other factors.

Low maintenance measurement stations
Each of the surrounding villages has measurement systems with INFRA sensors and a data logger installed. The sensors measure vibrations, shock waves and noise. All data is sent on the same bus cable from the sensors to the data logger. It manages communication to and from the measurement site using a wireless internet (GPRS) protocol. The system have been supplied by Sigicom and are operated by Vibroakustik – a small consulting firm that has enjoyed success working with major Swedish companies through their extensive measurement competence and far-sighted supplier strategy.

“I take care of all equipment handling using my computer and the Internet so I can do it from Thailand if I want. Once a year I need to retrieve the sensors for calibration. The measuring stations are supplied with electricity from the location where they are installed, so no battery changes are needed ”, says Vibroakustik’s
consultant Tony Larsson.

Excellent reporting and dialogue
Equally satisfied is Boliden’s measurement manager at the Aitik mine, Peter Palo. His job is to keep ore production flowing quickly and efficiently.

“The excellent reporting of measurement data is fully automatic and is displayed with a presentation program; this lets us keep vibration and noise below the stringent levels set-forth by the environmental authority. Furthermore, the gathered measurement data plays an important role in the development of our blasting technology . For example, it has allowed us to streamline blasts so that we have a fragmentation that makes the ore easier to load and faster to crush”, Peter Palo concludes.

With a hydraulic circuit in a tunnel with various other pits and tunnels for support and access. In order to eliminate liability for damages to the existing power plant, two INFRA systems with five sensors are used. Sensors on the turbine and the transformer make it possible to adapt the amount of explosives to an appropriate level when blasting very close. Five minutes before a blast is fired, a mass phone announcement is sent to all those concerned property owners in the area who wish to be informed. For each measurement a threshold is defined to fall a bit below the limit. If a reading recorded after the blast exceeds the threshold, the data logger sends a text message directly to mine operators and consultants. Everyone is then able to call up the easy to understand tables and charts showing the desired measurement data on their computer
screens. Tony produces a monthly outcome report that is sent to Boliden and from there to the Environmental Agency.

Clear dialogue with property owners is very important in order to avoid complaints. Those who wish may receive test reports and twice a year Boliden invites concerned parties to a meeting that explains what they are doing and to answer any questions residents may have.

Aitikgruvan, Vibrokonsult and Sigicom – a trilateral cooperation working well since 2009! Both Tony and Peter have nothing but praise for the measuring equipment, the reporting and support and service they have received. With each major expansion of ore new measurement challenges await. Together they have every chance of success.