Metso, which maintains close ties with Tharisa, believed that a drastic reduction in downtime could be achieved if the mine was to adopt its Megaliner™ mill lining concept. The Megaliner™ was developed by Metso as a practical means of reducing the inevitable downtime that occurs during liner replacement.
Fewer parts means faster installations
Conventional practice involves installing many pieces using bolts that need to be inserted from the inside of the mill. This process takes quite a lot of time and involves potentially hazardous work for the liner replacement crew. The Megaliner design, however, uses fewer and larger parts and has a unique attachment system. This dramatically improves safety and speeds up the change-out process.
Metso regional product support manager Duane Mathers describes how the process was handled at Tharisa.
“The mill was originally equipped with 180 liners that had to be removed individually, which was a very time-consuming process. Replacing them with Megaliner, however, was a different story. Thanks to the simplicity of the design, we required just 30 modules to reline the mill interior,” says Duane.
Despite a few first-time niggles, the process took just 38 hours, reducing planned downtime by no less than 10 hours. According to Duane, this can be improved still further.
“A factor that extended the process was the removal of the existing 180 liners by hand. In the future, we will only have to replace 30 units, which are easy to remove thanks to the design. We expect that this will bring the total time taken to less than 24 hours, reducing downtime by around 50% at the next reline.”
Not only is the Megaliner concept good news for the bottom lines of mill operators, it also means a significant improvement in operator safety, according to Metso mill lining support specialist Marcel Bode.
While Megaliner is a relatively new Metso development, it has already proved itself under the most trying of conditions. It was specifically designed for the mills operated by the Boliden-owned Aitik mine, Europe’s largest open cast copper mine situated in northern Sweden. Success in this challenging operation has led to its use extending to major mill sites all over the world and its application is by no means restricted to Metso-produced grinding mills.“The bolts used to attach the liners are secured from the outside of the mill, a positive factor towards worker safety. This eliminates the need to have people in the ‘danger-zone’ inside the mill. The liner handler operator can put the liners in place without assistance from other workers. In addition, Metso Liner Positioning System is used to provide the operator remote guidance during the process with the help of cameras, which further improves safety and speeds up installations”, says Marcel.