Continuous development and improvement of the IsaMills™ from their first installation in 1994 has resulted in a grinding machine that not only offers superior performance but also increased component life and decreased costs culminating in a reduction in maintenance and operating costs.
Horizontal layout for simple mill access
The most crucial part of any mill maintenance is access. Unlike conventional mills where maintenance is done inside the mill with the IsaMill™ the shell is removed from the mill internals making access easier and shutdowns faster. The IsaMill™ grinding chamber and discharge end are fixed to trolleys that sit on rails. Hydraulic rams move the grinding chamber along the support rails and expose the internal components of the mill for maintenance.
The advantages of the IsaMill's™ horizontal configuration include simple overhead (or mobile) crane requirements and simple media handling. Media can be dropped into the integrated media hopper and is retrieved and returned to the IsaMill™ via the IsaCharger™ media handling system
Easy start up after stops
Unlike alternative technologies the horizontal, 8 disc layout of the IsaMill™ means it starts easily even after being crash stopped at full load – all 8 discs are available to achieve breakaway torque through the settled media load.
The internal wear components
Over the last decade over 20 different types of wear materials have been tested in the IsaMill™ to determine the characteristics that components need for long wear life.
- Feed and Discharge end flanges – replaceable rubber wear component that slide onto the steel surfaces and then are bolted in place.
- Grinding Chamber (shell) – IsaMills™ are designed with a split shell in which a replaceable slip-in liner can be installed. The IsaMill™ shell can be unbolted, opened into two halves and the worn shell slip-in liner removed and a new one installed. There is no need to send the shell away for relining and have a spare shell on site.
- Grinding Disks – consist of 2 components a relatively cheap disposable disc and a more expensive reusable hub that connects the disk to the mill shaft.
All wear components are steel backed with rubber or similar coating. They are fabricated off-site then stored on-site until required. The components are relatively low cost, light and easy to handle and store while still providing long wear lives.
Shaft sealing system
The shaft sealing system prevents slurry and grinding media discharging from the point where the rotating shaft enters the grinding chamber. The gland seal packing is comparable to that used in slurry pumps and with consistant, good quality water supply can be expected to have a life of at least 6 months.
Maintenance of the IsaMill™ is as simple as routine maintenance for a slurry pump. The internal rotating shaft is counter-levered at the feed inlet end so the discharge end flange and grinding chamber can be simply unbolted and slid off (using hydraulic rams).
The grinding discs can be removed by undoing the locking nuts at the end of the shaft. The old discs are slid off and new discs slid on. The bolt-on wear components and shell liner can then be replaced (if required) before the shell is slid back into position and bolted up… the IsaMill™ is ready to run. Typical IsaMill™ shutdowns last 6-10 hrs
The maintenance schedule is built around the grinding discs, all other components last several cycles of disc replacement. Continuous improvement of all components have seen an increase in wear life and a drop in downtime and maintenance costs.
IsaMill™ component life is dependant on the application however grinding discs generally last up to 6 months and shell liners can last up to 1 year. Typically IsaMill™ maintenance takes 6-12 hours and is cheduled into routine planned shutdowns. With maintenance occurring every 6-8 weeks availability exceeds 97%.