Grinding mill finds continuous online surveillance of vibration to be cost effective after conversion from offline system.
Semi-autogenous grinding mills, also known simply as SAG mills, grind materials from large chunks into small, usable pieces for processing. The ones used in mining operations in Canada are essentially autogenous, but use grinding balls to aid in grinding, like in a ball mill. A SAG mill is generally used as a primary or first-stage grinding solution. Attrition between grinding balls and ore particles causes grinding of finer particles.
SAG mills are primarily used at gold, copper and platinum mines with applications also in the lead, zinc, silver, alumina and nickel industries. These mills are characterized by their large diameter and short length, as compared to ball mills. The inside of the mill is lined with lifting plates to lift the material inside the mill, where it then falls off the plates onto the rest of the ore charge.
The monitoring of this type of equipment is crucial for modern mining operations. Breakdowns lead essentially to a complete shutdown of the operation, unless enough redundancy exists. Most mining operations have moved away from breakdown maintenance to reliability-based maintenance concepts.
Aside from ultrasound, oil analysis and visual inspections, the vibration monitoring of rotating equipment plays an important role among these modern programs. Handheld FFT analyzers are commonly used and route-based data collection programs help a modern reliability engineer to keep track of the health status of his machine park.
In times of tight money, the biggest challenge remains the management of resources. To collect vibration data in a route-based monitoring program requires a big portion of a maintenance employee’s time, meaning they are not available to work on something else. For this reason, more and more companies have recognized that modern continuous monitoring concepts are more cost-efficient; they free the time of employees, increase the amount of monitoring data, reduce reaction time and eventually increase the reliability of a plant’s equipment.
Online monitoring system prices have dropped over the past decade and have become affordable for most companies. They also lead to direct cost savings by eliminating route-based data collection time. As well, they also increase the consistency of the vibration data as the sensors are permanently mounted and data is always recorded at the same position on the machine in a much more frequent manner than using offline, manual methods.