SCREENING TECHNOLOGY
Screening by design
General Kinematics says its proprietary STM- SCREEN™ operates beyond the finite design limitations of large brute force screens & is designed and constructed to process higher tonnages , at comminution circuit design efficiencies
From the latest design technology allowing lighter weight screens to moving beyond just making bigger screens to optimisation & design innovation , Paul Moore reviews trends in this crucial mineral processing area
In mining when it comes to screening there
has always been a feeling that heavier is better . However , a recent article by Steven Hunter , Weir Minerals Technology Group Leader – Separation says this has often resulted in exceptionally heavy screens over-engineered in all the wrong places .
“ New methods are radically changing the way screens are designed . Digital calculations , simulations , modelling and drafting allow designers more freedom to challenge traditional designs and make use of material advancements to build screens that are more reliable , safer and efficient without the need for unnecessary weight increases .”
Until this point screening has been unable to capitalise from the best practices shown in other industries due to the difficulties and inertia manual design entailed . “ As computer aided design has become more advanced , screen designers are now empowered to make wholesale changes to their product . The introduction of computer-simulated finite element analysis ( FEA ), has enabled design engineers to instantly validate any design changes made , a process that wasn ’ t previously possible .”
The result of such progression and innovation within the field of screening is often a differently shaped and weighted product . “ But don ’ t call them lightweight - while these screens may be lighter compared with previous models , our engineers ensure that they ’ re as heavy as they ’ re required to be .”
Weir ’ s Enduron ® screens are built specifically to meet project needs , with its engineers using the customer ’ s requirements , flowsheet and onsite data as the design ’ s foundation . “ Without modern design tools , it would be practically impossible to customise our equipment so fundamentally to meet the needs of a specific application , on a specific site . By identifying the specific features , size and wear materials required to excel in their intended application , our design engineers are free remove weight where the screen assembly is experiencing low stresses and thus decreasing both operational and manufacturing costs .”
In the old days , Hunter says you built screens big , heavy and padded out to try and ensure that if anything went wrong , it wouldn ’ t go catastrophically wrong . “ It was a brute force approach to safety , which if used today , produces an unnecessarily heavy screen . Today , there are a number of tools available to ensure there are no surprises when the time finally comes to physically test the equipment . Engineers run a natural frequency simulation to check that the screen will not run at its natural frequency when operated , which is vital to avoiding resonance which can cause premature failure in the equipment .”
A frequency response simulation is also used which enables the Weir team to analyse each design using the actual forces the screen will encounter on-site ( loaded and unloaded ). This allows the company to evaluate each part of the product for
high stress points and reinforce the screen where it ’ s actually useful .
“ Our design and testing processes are extensive and carried out by a team of experts , who combine experience with outside-of-the-box innovation . Our expert team tests new ideas and design philosophy against our extensive bank of successful , industry-leading designs and data gathered from real applications in mines and quarries around the world . Using these tools , our team can build screens which are optimised around a specific application ’ s requirements , rather than against any possible problem a screen could possibly face . This allows us to reduce the screen ’ s weight and complexity , benefits we pass on to our customers . This reduction in material also has knock on savings in terms of manufacturing time and transport costs , as well as lowering the weight required to lift and rig on-site , which makes installation and maintenance safer . However , this modern approach to screen design goes beyond material reduction .”
The added data and evaluation allow Weir to supply products which are easier to maintain , easier to operate , more efficient , require less power , and have access to alternative exciter and vibrating motor options .
“ The benefits of our new approach are clear . Using modern design tools , expertly customised screens can provide the robust construction and vital safety features you need without the excess baggage . Drawing on decades of working with screens , our designers pick and choose features
Weir Minerals ’ Steven Hunter , Technology Group Leader – Separation says just because Enduron ® screens can be built big , it doesn ' t mean they need to be built heavy
42 International Mining | OCTOBER 2020