Optimise SAG mill capacity and avoid unnecessary downtime
Every second counts with SAG mill optimisation
The loudest silence occurs when your SAG mill is standing still. It is the sound of rising costs by the hour both from the downtime itself and from maintenance costs. Optimising the capacity of your SAG mill is crucial to avoiding downtime and liner wear and damage.
With variances in mill ore feed rate, mill speed and slurry density, critical impacts can occur in your SAG mill. The speed at which these variances are adjusted for is thus crucial for minimizing damage and optimizing liner life. Every second counts, and adjusting these parameters within seconds can have a significant effect on the wear of your SAG mill, which will effect on your bottom line.
SAGwiseTM reduces your mill’s ball-on-liner impacts with up to 45 per cent, which prolongs liner life and minimises media degradation. Further, it reduces energy consumption by up to six percent.
Frequent and automatic mill load adjustments
SAGwise uses acoustic sensors and proprietary process control software to predict and adjust the SAG mill operation according to impacts on your mill and other main process variables. The acoustic sensors ensure regular and accurate adjustments to mill loading. This digital solution is inspired by experienced plant operators’ ability to listen to the mill load for critical steel-on-steel impacts and then adjust the mill load if critical impacts occur.
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.
Keeps the mill rolling
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 downtime. This can translate to literally millions more tonnes of ore milled.
Lightweight composite liners for large mills
Replacing traditional steel cast mill liners with new lightweight composite liners is another way to increase throughput of mills. Major gold and copper operations have already started doing this in mills up to 40’ Ø and seen an improvement in the slurry discharge of up to seven percent.
The composite liners are thinner than steel cast liners, and thinner liners result in a larger volume inside the mill. This means you can have a higher charge level. Using composite liners also cuts the weight of the liners to about 50 percent of standard steel cast liners, making it possible to work with a higher ball charge level without increasing the total weight of the mill. Both of these benefits result in a higher throughput.
ROI in half the lifetime
Where upgrading to a composite liner is the right solution, the return on investment is usually within half the lifetime of the wear part.
Like all upgrades there can be an increase in upfront costs, but the total cost of ownership value is simple to calculate. This value is manifested first by production improvements, often contributing seven figure values to a customer’s profitability. That improvement can stand on its own. However, with the improvements in downtime and reduction in safety risks, the values can be even greater.