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The remote monitoring system for Sandvik Rock Processing’s crushing equipment is an integral part of the automation and connectivity system (ACS) of each of its crushers.
The remote monitoring system for Sandvik Rock Processing’s (SRP’s) crushing equipment is an integral part of the automation and connectivity system (ACS) of each of its crushers. “The ACS will display the basic alarms should any important parameter be outside of normal operation limits. If, for example, the oil temperature is too high, or the pressure is higher because there is some tramp caught in the crusher. This will all be logged here on the ACS screen as an event history,” begins Nils-Peter Ahlqvist.
“But all the data the ACS system measures as part of normal machine operations is also being fed into our connected remote monitoring system, which we call SAM. What SAM does it is to collect, condense and analyse all the operational data that we have –excluding anything sensitive such as production figures or product sizes. This data is available, but only to onsite managers via their own secure SCADA system,” he continues.
Highlighting the SAM visualisation dashboard, he says that SAM presents an overview that summarises machine operation, highlighting instantaneous averages of key operational metrics such as average power being consumed, average pressure and, most importantly, the CSS (close side setting), which governs the particle size of material passing though the crusher. “Typically on a mine, the CSS will be fixed to suit downstream screen settings, but this setting needs to be regularly adjusted to compensate for wear,” Ahlqvist notes, adding that this can be automatically done on modern SRP’s cone crushers.
Describing how, he says that regular use of the calibration procedure helps the machine to learn over time, so that wear rates can be predicted. To calibrate the crusher, the feed is stopped, while crushing continues until the chamber of the machine is empty of all material. With the crusher now off, the main shaft that drives the gyrating cone is then raised by a hydraulic cylinder until it makes contact with the mantle. This position is reset as the zero CSS point before the hydraulics moves the cone back down to the operating CSS position.
“If the wear is constant, then the system can learn how to automatically reset the gap as time passes. This can reduce the calibration frequency and extend continuous running times, but there is always going to be some inconsistency, so calibration will still have to be done from time to time,” he points out.
“With SAM, though, there is a lot more we can look into to pick up operational changes and/or problems,” he continues, opening another data tracking dashboard of four critical crushing parameters: the CSS, the return oil temperature, the average motor power and the average hydraulic pressure. “Here you can see there is something happening,” he says pointing to a period where the CSS suddenly went from operating at 16 mm to opening up. “Something must have happened,” he notes.
Digging into the data, Ahlqvist looks for any alarms between 5:00 and 7:00 am on September 3. “Here you see there was an alarm. The main motor stopped with material in the chamber. So there was a blockage of some sort. The procedure for restarting the machine is also suggested as part of the alarm. In this case, the feed must be stopped so that the cone can be dropped to the fully open CSS position. Then, if there is nothing obvious still wedged between the cone and the shell, the motor can be started at slow speed to empty the chamber,” he tells MCA.
Moving back to the operational dashboard, he points out that this procedure was followed: when the motor was shut down, the CSS was opened and, when the motor was started again, the CSS was slowly brought back to its operating setpoint.
“What we tend to strive towards from an operating perspective is longer periods of trouble free operation with very few stoppages. And often the problem is not with the crusher, but in the feed conveyor. So SAM offers operators an insight into how to change its production parameters to better suit the crusher, which is often the bottleneck for the whole processing circuit,” he adds.
“An alarm of this type might take about five minutes to clear, but if you get 10 of those alarms per day, a lot of crushing minutes are wasted. By looking at the statistics behind the alarms, operators can start learning how to minimise the number of these alarms: by spending a little more time optimising the crusher settings and those of the conveyor feeding material into it.
“We also measure all temperatures for the lubrication system, and so on, so if the machine starts to run a dangerously high oil temperature, a similar alarm will warn of the consequences and suggest remedial action. And if any of the critical machine parameters we are measuring indicates that damage to the machine is likely, the machine will be automatically shut down so that remedial action can be taken,” concludes Nils-Peter Ahlqvist.
