REBUILDS & REFURBS
Routes to being reborn
In this annual look at equipment rebuilds and upgrades , Paul Moore spoke to three leading OEMs about their strategies , capabilities and recommendations to customers
Perhaps not what comes to mind in terms of
refurbishment and rebuilds , large continuous mining systems , including in-pit crushing and conveying systems , bring unique challenges in this area . IM spoke to Georg Leitner , FLSmidth Head of Global Technical Services about how these installations are managed to ensure optimal performance .
Leitner comments : “ In general , the most complex part of any IPCC system is the mobile crusher or sizer , especially in fully mobile systems where the setup is completely truckless . So these would require the greatest amount of maintenance attention including any refurbishments . But it is also true that most of these in the industry have been operating for ten years or less so there isn ’ t a great deal of experience in carrying out major overhauls on these as yet .” He adds : “ What the industry has seen so far is some issues with vibrations due to eccentric loading from shovels , the material impact on the crusher or sizer and also vibration coming from the crusher or sizer itself . These issues have been addressed with detailed vibration analysis combined with structural assessments and if necessary looking at some structural redesign of the machine . Specifically for FLSmidth we use our low speed ABON sizer , which operates at one third of the rotation speed of some other models which helps to reduce direct vibration effects . We are currently upgrading some fully mobile units in Brazil with our ABON technology , for example .”
Turning to IPCC conveyors , Leitner said they are assessed during use for any required recalculations on the mechanical and structural side – particularly where they are being extended or relocated to new ground profiles . “ Where capacity is being increased we also carry out chute optimisation DEM simulations for example to optimise material flow and minimise wear and dust generation .”
FLSmidth says the main unscheduled refurbishments on continuous mining machines in general are on mechanical and structural components where any failures occur – “ we come in and do a root cause analysis and a reassessment of the load assumptions and if needed carry out a full re-engineering plan in order to reduce any further unscheduled downtime and increase the replacement cycle of components .” Scheduled maintenance for things like sizers and bucketwheels can be planned one or two years in advance based on observed rates of wear and tear . The same is true with major slew bearings which is important as the delivery time can be six months or more . Regular maintenance on gears and drives is carried out by the mining company or operator with input from the drive OEM .
Georg Leitner , Head of Global Technical Services , FLSmidth
Work on an
FLSmidth bucketwheel replacement
In terms of any operational impact , upgrades on mining equipment are performed via detailed planning with the erection team ( engineering , supply , execution , erection ) to reduce the downtime to a minimum . “ Where possible small modifications can be installed in sequences to use the same downtime windows as required for regular maintenance ; only for major upgrades / partial machine replacement a shutdown window of two or three weeks may be required .”
Looking at electrics specifically , if not part of a major capacity upgrade where the demand drive power significantly changes , FLSmidth would not automatically upgrade the electrical system . “ On equipment which are 10 to 15 years old , we recommend to upgrade the PLC and HMI system to the latest technology . IPCC machines and equipment are designed to a lifetime of 20 to 25 years ; at that stage we would recommend replacing the entire electrical system of the machine together with a structural audit and mechanical overhaul .”
On what is expected at the outset it is dependent on the customer and specific project . In general , Leitner says the following should be contractually defined : n Availability usually 90 to 92 % (( Total Time – Maintenance Time – Delay Time – Delay Time from Owner )/( Total Operation Time – Delay from Owner )) n Reliability usually 95 to 98 % (( Operation Time – Delay Time )/( Total Operation Time – Delay from Owner ) n Performance ( ie capacity ) “ The reliability and performance are generally tested within an agreed time frame ( eg two months ). Not achieving the reliability or performance test are linked to a certain percentage value defined in the contract . There is no specific factor considered for refurbishment works .”
Finally , on analytics and sensors , Leitner said these can be a huge help , but can never avoid all unplanned stoppages . “ The sensors can help us to understand how the machines works , which helps us to create root causes analysis and perform a proper re-design to avoid such failures in future . To avoid unplanned stoppages is only possible with a combination of reliable machine design ( technical specifications / requirements ), inspections , proper maintenance and operator training . FLSmidth now offers Bulk Expert technology which allows for completely unmanned operation of mining and material handling equipment , which reduces the peak loads to the machine , which has a positive effect on the entire lifetime and reduction of unplanned stoppages .”
Epiroc ups the rebuild ante with battery retrofit
IM also caught up with Martin Wallman , Product Line Manager , Epiroc Parts & Services division and started with asking about upgrades – is the market
52 International Mining | FEBRUARY 2021