Richards was already familiar with the capabilities of Metso’s IS screens. The aggregates operation has used two of them on its production lines since 2003. After consulting with other Lafarge quarries, and even some local competitors about cone crushers, Richards was confident IS screens combined with the HP 400 was the way to go for its new line.
“There isn’t a better screen for the price, and with two IS screens already in place, it made perfect sense to install another one just like it,” Richards says. “Metso has been known for rock crushing for many, many years. Again, it came down to flexibility, the HP400 is a quality product that can handle increased throughput and generate the wide range of product gradation we were looking for — quickly.”
The large, conventional-sized inclined screens are designed to accept a wide range of deck media — a requirement of the Friendship Quarry. The adjustable speed and stroke enable the end-user to fine tune the IS to reach its peak productivity.
“The IS screens may not be custom-built for our application, but the design is flexible enough to handle all of our rock,” Richards says. “If there’s a screen out there that matches 95 percent of your needs, you don’t need a special design — especially if you have excellent distributor support and a company such as Metso willing to help you tweak it so the equipment will completely meet your needs.”
Richards says the company was able to stroke up to about 900 rpms from 700 to 800 rpms to use the screens to their fullest capacity. “We’ve cut plant run time by about 4 hours every day, or basically 20 hours a week,” he says. “My guys are now able to use that time for plant maintenance, which is very important to our operation for safety and productivity.”
Grease and go
Richards said ease of maintenance is a critical benefit of Metso’s IS screens, specifically the bearing packages of the MV “ Modular” vibrator and its lubrication method.
The IS screen’s bearings are grease lubricated as opposed to using a closed-loop, oil-based lubrication system. The grease lubrication design enables Richards’ crewmembers to lubricate the bearings on a weekly basis and be assured that the bearings have been purged. Many screens that use an oil-based lubrication system run a high risk of contamination. When using a closed-loop system, the catch is that the contaminant will be carried to other bearings in the system. This will cause multiple bearing failures and subsequent replacements.
The IS screens have standalone, modular, bearing cartridges on either side, connected with a drive shaft. As a result, if there is a bearing failure on one side of the screen, it won’t contaminate the other bearings.
Lafarge’s Friendship Quarry has used two IS screens on its production lines since 2003.
This capability also increases the ability to service the screen. In the event a bearing does need replacement, the cartridge “pops” out, and the operator can make a quick replacement in less than an hour. A complete teardown of the screen is unnecessary, which reduces downtime.
Although automatic greasing units are available, Richards likes the fact that employees are physically going into the system and performing the lubrication themselves. Many times, problems get overlooked using screens with an oil lubrication system.
“With an oil-lubricated machine, the perception is that as long as it’s not leaking, you don’t need to worry, but you still have to check the oil level, and the potential for contamination is always a concern,” Richards says. “My guys are going to perform their visual inspections every night and when they open the machine up, they’re going to grease the bearings. The Metso screens are very easy to maintain. As long as you grease the bearings, they’ll run for a very long time with very little effort.”