SBM Vertical Mill

Vertical Mill Maintenance Of Wear Parts

Vertical Mill technology was new to the Phoenix plant. During the initial operating period this proved to present many opportunities for new experiences and required a relatively steep learning curve that was not present with the ball mills. Despite the new skills to be learned and many new procedures to follow the process has been relatively smooth. Unexpected circumstances may present themselves at inopportune times; however the vertical mill has only had minimal down time.

The longest continuous period that the mill was stopped was 66 hours during roller maintenance. To date the reliability of the mill gives every indication that this will be the norm for the life of the system.

Through the first 2 years of full production the general trend indicates that maintenance costs are on the same level or slightly lower than for ball mills. It is expected that they will actually decrease as experience is gained and best practices are refined by the maintenance crew.

Wear
The vertical mill design allows the option of rotating the roller segments 180 degrees before replacing. They can also be hardfaced in place with a standard rewelding procedure. The table liners can also be replaced or hardfaced. As of this time both methods have been undertaken.

After the mill was in operation for over 10,000 hours the roller and table wear rates have been measured 2 times, once through each method described above, roller segment rotation and rewelding of both the table and roller liners. The actual wear rate for both the roller and table liners before hardfacing was 0.30 g/T. The measured wear rate with hardfaced liners was 0.12 g/T. The 50% reduction in wear rate with hardfaced liners was expected as data from other vertical cement mills indicated such a savings could be expected. In either case the wear rate has exceeded expectations and operation has not been detrimentally effected by wear.