Avoiding major breakdowns with the help of monitoring

On-going trials to secure a reliable system at Boliden Kevitsa 

Boliden’s Kevitsa mine in Finland has been looking to acquire good quality and useful data to support the daily maintenance operations and procedures at the plant. It is all part of the company’s plan to increase uptime and cut operational costs. The average availability of its equipment was 93% when the project started. The availability has since increased, but the mine is looking to increase these numbers even further. Monitoring the screens is part of the strategy.

In June 2019, Metso Outotec installed a monitoring system on the MF screen at Boliden Kevitsa and less than a year later also on the RF screen. It was, and still is, a pilot test with the intention to let Metso Outotec closely monitor and follow up in order to improve the system and its reliability.

Matti Mustonen, Deployment Specialist at Metso Outotec, closely follows the digital platform and filters the alarms to set acceptable limits.

“I check the system regularly, follow up on alarms, and have regular contact with the customer. We had a lot of challenges in the beginning, as the system was a bit too sensitive. However, that has been sorted out and now it’s a robust system that helps us catch the relevant issues,” says Matti.

Metso Outotec and Boliden Kevitsa have had close cooperation since Boliden bought the Kevitsa site in 2016. The trust that has been built up between the companies has facilitated the collaboration on new development.

“I am pleased with the monitoring system and how the trial has been handled. Metso Outotec has been very proactive. They have a willingness to improve and have been very innovative. I have noticed that they have clearly taken an ownership in this project, which has helped us get back on track and has pushed the development forward,” says Tuomas Vahteristo, Head of Section Preventive Maintenance at Boliden Kevitsa Mining Oy.

Several potential breakdowns avoided

“The system has been very useful. Knowing the condition of your equipment at all times is important. It has helped us optimize the process, as we can easily see if the changes implemented have had a positive effect or not. In addition, several potential breakdowns have been avoided. 2021 has been the best year so far, in terms of minimizing breakdowns,” concludes Tuomas.  

The system has proven its value from the start, and three potential issues were recently discovered. Tuomas Vahteristo and Matti Mustonen explain the issues reported, the actions taken, and what the consequences might have been if not detected in time.

1. Exciter temperatures exceeding the limits

Issue reported: In the middle of October, Matti noticed that the MF screen’s exciter left temperature showed 75°C, which was clearly higher than usual. He double checked and also saw an increase in bearing noise in the trend view. 

Action: Kevitsa was informed and was asked to check with a thermographic camera and to also check the oil. With the temperature increase confirmed and particles and dirt found in the oil, Kevitsa started planning for an extra stop three days later. The early warning gave them time to fill intermediate storages of ore so that they could changeout the exciter without losing production. The old mechanism was sent for maintenance and will be returned to the site for use as a spare.

Consequence if not detected early: It is likely that this kind of mechanical problem would have lead to a total breakdown if it hadn’t been detected early. The consequences could have been extensive with major damages on the screen structure. A breakdown would have caused a maintenance stop of at least eight hours and a bigger safety risk.

2. Missing sideliners

Issue reported: In November 2021, a potential failure in the RF screen was detected. A clear difference in Orbits, Motion acceleration, and especially Feed Left Transverse Acceleration and Motion were noticed via the monitoring system.

Action: The customer was informed right away and made the decision to stop the screen the day after to check. The finding was that two sideliners were missing – most likely they had somehow become loose and dropped. New sideliners were installed and the normal screen operation was restored.

Consequence if not detected early: Missing liners will result in excessive wear of the screen body but more than that, a typical subsequent failure could be serious damages of the screen deck frame caused by the flapping screen panels. In addition, with liners coming loose, panels may dislodge and have the potential to cause major issues downstream.

3. Rock blockage below the isolation frame

Issue reported: In October 2021, the system showed a deviation in how the MF screen was operating. The orbits shape was different at the discharge end.

Action: The customer was asked to check the screen. The MF screen was stopped and it was discovered that a rock was blocking the isolation frame. The rock was removed and the screen was put back into operation. The blockage did not cause any damage to the screen body.

Consequence if not detected early: Structural damage to the isolation frame or the screen body, not only due to the physical contact but also due to the uneven motion over time.

Planned maintenance saves time and money 

Mining sites need to deal with assets in a systematic way, as the budget is set for the lifespan of the mine. The equipment is fairly expensive, so it is important to predict how long each machine will last. If one piece of equipment fails, it could be difficult to get the capital needed to replace it.

Knowing the actual value of a monitoring system is difficult, as no one knows when the issues may have otherwise been discovered. However, one hour of production loss costs tens of thousands euros, which means that every hour counts. In addition, a planned maintenance break means that it can be scheduled on a day and time that is more optimal and that other tasks can be addressed at the same time.  

”Everything you can plan for will save costs, in terms of labor, spare parts, and production. And there is always something else that can be done during a critical equipment shutdown. A monitoring system offers the time needed to make valuable preparations and to use the time wisely,” says Tuomas.

Remote monitoring offers peace of mind

Mining companies have a lot of equipment; closely following the data and trends generated by different monitoring systems can be time consuming on top of the daily work. There is still a need to have a simple overview at the site, but additionally remote monitoring as a service is being requested from the original equipment manufacturer.

”We have to rely on the manufacturer to catch early deviations and for detailed analyses. The supplier has and should continue to have the technical knowledge and interest in developing the equipment. I’d like to see screening-as-a-service kind of agreement where the availability of the screen and the total life cycle cost of the machine are granted. That benefits both us and the manufacturer,” says Tuomas.