By analysing the sound and other process parameters, SAGwise™ adjusts mill load and decreases steel-on-steel impact, resulting in less energy consumption and increased production.
Operating a SAG mill is a costly affair. Yet, a SAG mill is most costly as when it stand still. Therefore, being able to predict the right mill load optimises the output and minimise repairs and standstills is of utmost importance.
Today, experienced plant operators depend on the personnel close to the SAG mill listening to the mill load for critical steel-on-steel impacts. If critical impacts occur, they manually adjust the SAG mill load to make the mill run smoothly. Though this is a qualified way of handling critical impacts, a new digital solution utilises acoustics sensors to reduce downtime and increase the mill’s reliability and productivity.
Acoustic sensors optimise SAG mill operation
The new FLSmidth SAGwise™ process-control uses acoustic sensors and proprietary process control software to predict and adjust the SAG mill operation according to impacts on the mill and other main process variables. The acoustic sensors ensure regular and accurate adjustments to mill loading.
The solution employs state-of-the-art process-control technologies to reduce critical impacts to the desired targets; stabilising and optimising the SAG mill’s operation. The solution embeds multiple process-control technologies, modelling both the process and the human operators.
“Within seconds, SAGwise can analyse audio frequencies as well as on board power usage, mill weight and bearing pressure. It can then automatically take corrective action if needed and adjust parameters such as the mill ore feed rate, mill speed or slurry density. Where an operator might make adjustments every few minutes, this solution can make less drastic adjustments more frequently, down to every 20 seconds or less,” says King Becerra, Global Product Line Manager for Automation Process Optimisation.
Test results show that these adjustments reduce damage to the liners by up to 40 percent. This means less unscheduled downtime and increase in production.
“The one sound operators do not want to hear is the sound of the mills standing still. A gold-processing plant, I visited recently valued their SAG mill downtime at US$ 130,000 per hour, so extending the life and availability of mill liners is crucial to them. The reduced damage improves the mills availability and minimises the down time. This can translate to literally millions more tonnes of ore milled,” says Jack Meegan, Global Product Line Manager for Mill Liners.
ROI in six months
“We want to make sure that our customers are getting more value from their liners as well as from their media. With many mines using $10 million or more on liners per year and 3 or 4 times this cost in terms of grinding media, the savings can be huge,” says Meegan.
Test results also show a reduced energy consumption of up to six percent. Considering that mills are the largest power consumer in minerals processing, this is quite significant. Furthermore, the new solution resulted in a six percent production increase and reduced process variability by up to 30 percent. With these savings, SAGwise can pay for itself within six months or less.
How does it work
Audio sensors close to the SAG mill listen for undesirable high-energy critical impacts. Intelligent software analyses the patterns and adjust feed, speed and pulp density for optimal efficiency to decrease power usage, reduce critical impacts and preserve liner life.
- Increase liner life
- Decrease critical impact by up to 45%
- Up to 6% reduction in grinding specific power consumption
- Up to 30% reduction in process variability
- Minimised downtime
- Reduce ball consumption