Modern Mining May 2021

CRUSHING, MILLING AND SCREENING

New trends in the field of comminution include reduced ore grades, low-energy dry comminution, high-pressure grinding rolls, stirred mills and hybrid power supplies. We take a closer look at these and how they help to meet the industry’s need for improved efficiencies. By Mark Botha. New trends in comminution technology

W hen asked about new trends and advances in comminution technologies, FLSmidth director of product and account manage- ment for sub-Saharan Africa and the Middle East, Terence Osborn, points to a reduction in ore grade in recent years, meaning that minerals are being disseminated more finely. “This means more grinding, as a finer particle size distribution is required to recover the same volume of minerals,” he says. FLSmidth has a number of focused technologies in this area, including its VXP vertical stirred mill with ceramic grinding media, which allows for product particle size distributions of 15 micron and below. “We have also recently sold our first tower mill for a regrind application,” says Osborn. “Tower mills use steel grinding media, but achieve finer product distributions than ball mills.” He says there are “strong advances” in digital solutions in comminution technologies. These drive greater efficiency, reduce costs through reduced power usage and water consumption. This, in turn, improves the bottom line while conserving the environment. “These technologies feed more real-time data back to the operations team, allowing quicker and more proactive management of changing process conditions for the most efficient treatment of ore.” FLSmidth has launched two key products in this area: the Millscanner from the recently-acquired

digital optimisation solutions company Know­ ledgeScape, and the smart gyratory crusher. According to Osborn, a wide array of sensors and optical devices is now available to support real-time crusher monitoring. “The results produced by these devices allow the crusher to be operated under its most efficient conditions. Monitoring the settings and output from each crusher using modern control systems ensures that a constant product is fed to the screens for bet- ter system stability and more consistent process results.” He says sensors also provide a better under- standing of component wear, so that maintenance can be planned proactively, and change-outs are scheduled to prevent downtime due to failure. “Some of the sensors added to our Mark V range gyratory crushers, for instance, can monitor vibra- tion, temperature, oil flow and oil condition.” “Key trends in the industry that we have noted,” says Weir Minerals Africa GMTiisetsoMasekwamang, “are low-energy dry comminution seen in equipment like Weir Minerals’ Enduron high-pressure grinding rolls (HPGRs), as well as advancements such as our Synertrex smart analytics platforms for online condi- tion monitoring of comminution equipment.” She says these trends “align well” with growing trends to reduce energy and water consumption and so create a more efficient processing plant. Wirtgen Group South Africa sales manager

FLSmidth’s stirred mills are more energy-efficient than ball mills.

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22  MODERN MINING  May 2021