SCREENING
All hands on deck
Weir ’ s new ENDURON
®
ELITE screen is a large , high capacity , double-deck , mining-specific machine
Screening plays a vital role in separation from the big tonnage iron ore and copper mines right down to specialist industrial and critical minerals operations . Paul Moore looks at some developments
Screening is one of the oldest mineral processing methods known , but in its most modern forms it is still being factored into the latest forward thinking flowsheet designs . A good example is from Weir , which has recently expanded its range of ENDURON ® screens . Its ENDURON ® ELITE screen , which was recently unveiled at MINExpo 2024 , is a large , highcapacity banana screen , available in a range of sizes with the largest weighing in at close to 50 t .
With the mining industry increasingly focused on sustainability and Weir ’ s commitment to helping its customers reduce their energy consumption in the grinding circuit , Weir has developed its transformational flowsheet solution , which replaces traditional tumbling mills with HPGRs and vertical stirred mills . This solution needs screening both upstream and downstream of the HPGR , which produces high tonnage , fine material requiring small separation sizes . Notably , by screening HPGR discharge product at 1 mm , Weir ’ s transformational flowsheet only requires a single vertical stirred mill , delivering significant energy reductions compared to conventional grinding circuits . The industry is also dealing with the challenges of declining ore grades and fewer large mines coming into operations , meaning that existing mines need to process higher tonnages , which , in turn , requires higher screening capacity .
This presents some design challenges ; perhaps most significantly , Weir had to develop an exciter capable of driving a screen with a deck that spans 4.27 m . This has been a long and rigorous process that involved initially designing a range of exciters , building and testing prototypes and then commercialising a serial production version . Screens of this size typically require three exciters , but this increases the amount of deflection experienced in the exciter beam , resulting in heavy exciter beam designs . In contrast , the two exciters on the ENDURON ® ELITE screens are mounted closer to the sideplates , which reduces the force acting on the middle of the exciter beam . Moving the exciters closer to the sideplates also reduces the localised bending moment at the beam and sideplate interface .
There are also operational benefits because it means there are less exciters to maintain on-site , which reduces downtime , routine inspections and
inventory management .
Weir was recently awarded a £ 53 million contract to provide a transformational flowsheet for Barrick Gold ’ s Reko Diq copper-gold project in Balochistan Province , Pakistan , which includes 12 4.27 m x 8.54 m double deck ENDURON ® ELITE banana screens driven by two ETX200 exciters . Weir told IM that this is further proof that top miners trust Weir to deliver critical products for their big greenfield projects .
During the project tender phase , Weir can test its customers ’ material at its Venlo Technology Hub ( VTH ). It can accurately determine the HPGR discharge PSD , allowing it to select the correct screen size and configuration . Whereas most facilities use normal horizontal or inclined screens for testing , Weir has a pilot double-deck banana test screen at the VTH , allowing it to replicate the actual operating conditions more accurately .
Weir ’ s new ENDURON ® ORBITAL vibrating screen is suited to lower throughput mining and sand and aggregate operations and has been designed to maximise service life and availability .
This has led Weir to opt for an all-bolted construction , removing all welding from the main screen body . Put simply , most screen failures are caused from high stress in welded joints , so eliminating these ensures a more reliable machine .
Weir has developed the ORBITAL screen with the same design specifications it used on its ELITE screens , meaning that it bridges the divide between typical sand and aggregate screens and large hard rock mining screens .
In other words , the ENDURON ® ORBITAL screen fills an important gap in the market for smaller , lower tonnage mining operations . It is well suited to crushing circuits in both secondary and tertiary screening duties , as long as top size is limited to < 150 mm .
It has also been engineered with a wide operating window , providing flexibility to change the screen settings in line with the operating conditions and eliminating failures related to natural frequencies often associated with vibrating screens .
Providing customers with a high level of flexibility was prioritised and has informed other aspects of the screen ’ s design . For instance , the ENDURON ® ORBITAL screens can accommodate both modular flat decks and side-tension crown decks on the same deck structure .
Moreover , this modular screen construction extends to other parts of the screen ; most of the components – decks , crossbeams , exciters , for example – are interchangeable within particular
32 International Mining | OCTOBER 2024