FLSmidth has just launched a new SAG mill liner protection solution called SAGwise™ total process control, with an estimate of less than six months ROI. It has been shown in tests that it can reduce damage to the liners by over 40%. FLSmidth told IM: “Extending the life and availability of mill liners is crucial. Weighing up to 4 t a piece, mill liners require a lot of effort to replace when they are worn out, and SAG mill downtime can be around $130,000/h, while lead times can span months. Overall it can cost well over $1 million dollars for a liner package.”
As stated, test results of the new product show reduced damage to the liners of 40% and an ROI of six months (without factoring in reduced unscheduled maintenance). Added this are reduced energy consumption of 6% – significant considering that mills use the by far largest amount of power required for minerals processing. The new solution also saw a production increase of 6% and reduced process variability up to 30%. The SAGwise™ total process control solution employs state of the art process control technologies to reduce critical impacts to the desired targets, stabilising and then optimising the operation of the SAG mill. Multiple process control technologies, such as model predictive control and fuzzy logic are embedded into the solution, modelling both the process and the human operators.
The system is based on 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. King Becerra, FLSmidth Global Product Line Manager – Process Optimisation told IM: “There are eight audio sensors on a bidirectional mill, four on each side. These have embedded microphones that listen for so-called critical steel on steel impacts between balls and liners rather than between ore and liners. Today, plant operators rely on the personnel close to the SAG mill listening to the mill load and undesirable steel-on-steel impacts to manually adjust the SAG mill operation, reducing undesirable impacts, and run the mill smoothly. But the FLSmidth SAGwise™ system takes this digital audio data and uses techniques such as model predictive control and fuzzy logic rules to assess the mill process parameters.”
“Within seconds it has analysed the audio frequencies as well as taking 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 water usage. Whereas an operator might make adjustments every few minutes, SAGwise™ can make more frequent (every 20 seconds or less) and less drastic adjustments.” The reduced damage improves mill availability and reduces downtime. “This can translate to literally multiple millions more tonnes of ore milled,” says FLSmidth.
Jack Meegan, FLSmidth Global Product Line Manager – Mill Liners and Wear Parts told IM: “We took technology that we already have and mated them together to make a solution. We can say to the customer, of course we want to sell you mill liners, but at the same time we want to make sure you are getting more value from your liners as well as your media. With many mines using $10 million or more of liners per year and three or four times this cost in terms of grinding media, the savings can be huge.”