HEAVY ENGINEERING & WEAR PARTS
noise having been verified in high impact shovel loading operations .
The Overwatch system is being installed in mining and aggregate locations across North America over the coming months . This will expand the data to include trucks from 40 tons to 300 tons , in ores and aggregates . This broader data will aid both GRT-Valley Rubber and its RTBL customers in better understanding the performance benefits of RTBL , it says .
GRT-Valley Rubber concluded : “ With this knowledge , end users can improve maintenance planning , document reduced maintenance cost and improve asset life , contributing to better overall asset management .”
Improving the profile
At ME Elecmetal , the ME FIT Solutions strategy focuses on improving its clients ’ operations , with a recent example of this coming from the enhancement of the crushing chamber profile of an FLSmidth model Raptor XL 1100 pebble crusher .
Field observations of the wear behaviour of the crusher wear parts , supported by in-depth data analysis , allowed the ME FIT Crushing team to propose an improved profile . The original profile did not match the feed material requirements for this application , with oversized particles blocking the crushing chamber ’ s upper zone , resulting in inefficient comminution and liner wear .
“ In the context of the day-to-day operations of a plant , it is easy to overlook such disruptions , leading to underutilisation of the steel available for wear and the crusher ’ s capacity ,” the company said . “ We also found that maintaining an optimal setting throughout the operation was impossible .”
Nicolás Moya , ME Elecmetal Sales Engineer , said : “ We wanted to find operational connectivity between the pebble crusher and the grinding processes . Before the modifications , there was an asynchrony between the product produced by the crushers and what the ball mills required . The pebbles move forward to the ball mill in this operation ’ s milling circuit .”
Once the company collected and analysed the technical reports on the wear condition of the original liners , it shared its recommendations with the client , agreeing to develop a new crushing chamber profile to accommodate the particle sizes discharged from the SAG mill instead of changing the SAG grate slot sizes .
“ The optimised pebble-crushing chamber profile ensured the crusher would operate at the required setting to produce excellent ball mill feed while maintaining an optimum crushing chamber wear profile throughout the campaign ,” the company said .
ME produced and installed the new profile wear liners with minimal inconvenience to the
Weir Minerals ’ proprietary liquid compounding method for manufacturing its Linatex Premium Rubber gently blends the latex , causing minimal damage to the microstructure of the rubber , the company says
client , it said . The crusher started with similar feed material conditions as that presented to the original crushing chamber profiles . The project team expected a higher production rate from the new chamber profile due to its greater volumetric capacity .
“ The result was the upper zone of the crushing chamber accepted and processed the coarse material much better ,” it said . “ The benefits of the optimised crushing chamber include decreased vibrations , increased load feed rate and higher power consumption .”
After 30 campaign days of the new design , the average crusher closed size setting ( CSS ) reduced from 13.1 mm to 11.45 mm . In other words , the new design allows adjusting to a smaller size , stabilising the equipment and benefitting the downstream operation , ME said .
Comparing the power draw of the campaigns with the new design profile with the analysed historical record revealed the optimised profile better uses the available power .
“ This increased utilisation of the crushing chamber results in higher equipment production ,” it said . “ The increase in material intake sizes , meanwhile , allows a more expeditious advance of the load towards areas of active crushing , so that the ore takes less time to reach the crushing areas .”
The hours of active operation were another of the measurements in which the new design stood out , going from , on average , 4.6 h / d to 6.1 h / d . And , during the campaign with the new liners , it was possible to achieve higher filling levels than with the previous design .
Despite increasing the crusher ’ s effective feed zone volume , the reduced CSS also implied reduced open sized setting ; thus , the ore remains in the chamber longer , maximising the fill volume .
“ When comparing the crusher chamber profiles , the new profile ensures better utilisation of the available liner steel : the mantle wear profile is homogeneous , without points of localised wear ,” ME Elecmetal added .
Complete rubber wear lining solution
Natural rubber has been proven as a very successful abrasion-resistant material , particularly in handling slurry applications , with its inherent properties – strength , resilience and cut resistance – having a direct effect on wear performance .
“ Crucially , these wear properties are at their best straight from the tree ; the more work that is
put into mixing the rubber , the more these properties are destroyed by the shearing and the breaking up of the long molecular chains ,” Mark Doyle , Global Product Manager for Rubber and Hose at Weir Minerals , says .
Conventional dry processing is based on shearing the rubber during mixing , which reduces the average molecular weight distribution and leads to a significant drop off in properties and performance , according to Doyle . Contrastingly , Weir Minerals ’ proprietary liquid compounding method for manufacturing its Linatex ® Premium Rubber gently blends the latex , causing minimal damage to the microstructure of the rubber .
There are many factors to consider when selecting the most appropriate compound for an application , according to Doyle .
First , the rubber ’ s thickness is typically increased when the particles are larger and heavier ; similarly , when the particles impact the rubber from height , the thickness is usually increased to better absorb the comprehensive forces .
As the particle hits the surface , the rubber deforms , absorbing the kinetic energy of the particle . The resilient nature of rubber returns most of this energy to the particle , causing it to rebound . There will be little or no wear and no permanent deformation , according to Doyle . However , if the particle momentum is too great relative to the rubber thickness , the impact force cannot be absorbed , and the rubber may cut or tear .
In impact and sliding abrasion situations , there is a critical speed above which elastomers are unable to recover and absorb energy . In this case , the product ’ s resilience cannot be used to its full extent and the surface may deteriorate more rapidly .
Moreover , the angle of the impact of the particle relative to the wear surface is also significant when it comes to designing chutes , hoppers and rubber linings , in general , since it affects the rate of wear .
For instance , at 90 ° impact angle , resilience is the major factor in resisting wear , but , as the impact angle reduces to around 50 °, tear resistance becomes more important . At very low impact angles , for wet sliding abrasion , slurries are best handled by Linatex rubber , according to Doyle . This applies to pipe lining and chute lining and applications involving general sliding wear ,
50 International Mining | JUNE 2023