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Mining and metals refining
Apr 17, 2020

Mill repair supervision at Kola MMC in Russia ensured continuous production

Outotec provided riding rings, bearing pads, a package of spare parts and supervision services for the repair of mill 23 at Norilsk Nickel’s Kola MMC to ensure continuous production at the concentrator plant. Kolskaya Mining and Metallurgical Company (Kola MMC) is a subsidiary of PJSC “MMC “Norilsk Nickel”.

The largest precious and non-ferrous metals producer in Russia

Norilsk Nickel, the world's largest producer of refined nickel and palladium and a leading producer of platinum, cobalt, copper and rhodium.  The company also produces gold, silver, iridium, selenium, ruthenium and tellurium.

Kolskaya Mining and Metallurgical Company (Kola MMC) is a leading industrial facility in the Murmansk Region. Kola MMC produces copper-nickel sulphide disseminated ores containing nickel, copper and other commercial components.

The mills delivered by Outokumpu are still in operation

Kola MMC operates two grinding mills delivered by Outokumpu and commissioned during 1988 and 1989. The mill is a unique design featuring bearing riding rings running on large hydrodynamic shoe bearings. There is a limited number of mills of this kind still operational worldwide. The grinding mill design life was 20+ years however Kola MMC has taken good care of the mills allowing for almost 30 years of uninterrupted operation. 

A crack in one the bearing riding rings called for repair

One of the bearing riding rings was fractured in the place where the ring is fastened to the mill. The result of such fracture could be an emergency stop resulting in lowering the production of the plant by one third. The time allocated for repair works was strictly limited. The task had to be completed within 27 days.

In February 2018 Outotec specialists performed visual examinations and recommended to perform emergency repair works (weld the fracture and fortify it with the plates) in order to keep the mill operational until the arrival of the new riding rings. Outotec and Kola MMC made a detailed work and time schedule that described the works step-by-step and eliminated the risk of delay.

As a solution Outotec provided repair supervision and delivered two new riding rings together with a number of bearings to bring the mill bearing system to its original condition. Manufacturing and delivery of the new rings took 9 months. The repair works commenced during November 2019.

In order to follow the schedule of the project two pairs of Outotec specialists worked in 12-hour shifts together with three subcontractor brigades on 8-hour shifts. For the duration of the repair a command center was established which followed up on the time schedule.

Challenges along the way

During the repair works it came to light that some additional bearings required replacement, this extended the project completion time due to the need to order, deliver and install additional bearings. After negotiations with Kola MMC the schedule was extended by 12 days. The time was crucial for Kola MMC as a 1 day production stop reduces the production output of the processing plant by 30%.

Anticipated result

Outotec expertise in repair of this unique 30-year-old grinding mill ensured continued operation at Kola MMC. The high level of expertise and cooperation of Kola MMC contributed to successful project implementation.

*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.

The mills are uniquely designed since the driving gear is connected through hydrostatic bearings. There is a limited number of mills of this kind still operational worldwide.
The mills are uniquely designed since the driving gear is connected through hydrostatic bearings. There is a limited number of mills of this kind still operational worldwide.
The high level of expertise and cooperation of Kola MMC contributed to successful project implementation.
The high level of expertise and cooperation of Kola MMC contributed to successful project implementation.
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