Re: Tramp Metal Protection Devices
Hi Tom,
Large tonnages usually means steel cord belts so there is the start of the problem. Tramp metal detectors usually use magnets and the magnets will eventually create a field in the steel cord reinforcing that creates error signals. You then de-sensitise the magnets but as the belt cover wears so you have to de-sensitise it more. Never ending story. So first step, only install tramp metal detectors on fabric belts. If you have to install them on a steel cord belt then realise you need very heavy top covers, the system will not be as good and you need a marker on each splice to ensure that the system turns off or ignores a splice (there is more steel cords in the splice than in the parent belt)
Hope this helps, for more specific information I would need to know a lot more about your system and the issues
Cheers
Colin Benjamin
Gulf Conveyor Systems Pty Ltd
www.conveyorsystemstechnology.com ■
Bolts On A Stable Door.
Originally Posted by Tom Christophersen
.......We're conveying iron ore at about 10,000t/hr, and use steel cord belt.
Cheers,
Tom
Now is too late to examine detection
. You can only reduce the tramp metal input at source.
Methought W.A. was better at this kind of thing: until I worked there and saw for meself.
■
Better Chute Design Is Needed
You might try look at improving the chute design. By example, we designed a curved chute for a 8,000 t/h and now about 11,000 t/h system copper mine in Chile. The present belt operates at 7 m/s.
The initial chute design was capable of transporting up to 400 mm primary crushed rock with belt speed of 6 m/s and 8000 t/h. The chute passed gyratory liners weighing > one ton and having substantialy more dimensions than 400 mm. I understand 23 liners passed and then one liner stayed upright onto the receiving belt and its heigth (> 600 mm) caught a steel crossbar. Then not so good. The crossbars were then removed.
The tonnage went to 11,000 t/h with large primary crushed rock and worked well until a 1100 mm spear bridged the opening. Further widening has not gone without incident.
In conclusion, the chute can handle the tramp metal and large rock without damage to the belt, even at reasonably high belt speed and tonnage.
ROCKY DEM can give the insight you need to test your hypothesis on chute geometry and contaminants. Or, send the chute design to CDI and we will make the necessary changes to the geometry for you. ■
Re: Tramp Metal Protection Devices
Sorry: scratch the double negative.
"Further widening has not gone without incident." should read: " Has gone without incident." ■
Tm Detector
Hello Tom,
I take it that your detectors are in themselves equipped with a belt joint detector that sets off the main detector when the joints make their pass?
Also, sometimes it's necessary to mount special idlers in the vicinity of the detectors, OEM should+must+ought give main input on this (and beware if they don't).
In the end, those neighboring idlers must be electrically "circuited" to base framework, by contact washer or contact weld or so.
R. ■
Re: Tramp Metal Protection Devices
Hi Colin,
Unfortunately steel cord is all we use. Cover thickness varies from 13x5 up to 22x7. We have magnets before some of our metal detectors, but not all. The splice detection function has been enabled only on the devices that have been giving us large numbers of false trips.
By the sounds of it we've installed metal detectors in the worst application possible! Is it worth spending a lot of resources fine-tuning these devices, or is there another way to separate out tramp metal we should be focusing on?
Tom ■
Re: Tramp Metal Protection Devices
Originally Posted by Roland Heilmann.................Also, sometimes it's necessary to mount special idlers in the vicinity of the detectors, OEM should+must+ought give main input on this (and beware if they don't).
In the end, those neighboring idlers must be electrically "circuited" to base framework, by contact washer or contact weld or so.
Hi Roland,
We have not installed (nor have been advised to install, as far as I know) any special idlers around the TMDs. We use standard steel idlers, which should have a good contact electrical connection with the frames. Last week we installed some poly shelled idlers in the two frames either side of one of our TMDs, in the hope that it will reduce the number of false trips. If this works we will look at doing the same on the other TMDs we have.
Tom ■
Re: Tramp Metal Protection Devices
Originally Posted by nordellWe use training/profiling plates in our chutes to profile the ore stream on the belt. Is there a way that we can still do this with minimal risk of belt damage from tramp metal? Or can the ore profile be optimised without the use of 'height restriction' chute hardware? ■
Re: Tramp Metal Protection Devices
Hi Tom,
Rather than fine tune the systems that are collecting the tramp metal on the belts (this is not very efficient usually especially at the tonnages you are running at as a lot of the metal is buried too far into the load to be picked up by the magnets) could I suggest you look at setting up your magnets at or over a transfer point(s). This will require you to use non magnetic material at the top of the transfer (eg stainless) and to have the transfer designed and set up well so that there is controlled flow. I think this option offers a lot more promise than persisting with the issues you currently have.
Cheers
Colin Benjamin
Gulf Conveyor Systems Pty Ltd
colin.benjamin@gcsm.com.au
www.conveyorsystemstechnology.com ■
Tramp Metal Protection Devices
Hi All,
We have several metal detectors and magnets installed on conveyors at our plant, however we continue to find belts damaged by tramp metal. We are considering installing more metal detectors, but the ones we have still give us numerous delays due to false trips, so many people are hesitant.
Has anyone had experience in setting up maintenance strategies for these devices to ensure they remain effective while minimising false trips? What considerations should be made during installation to achieve this (proximity to structure or other devices, type of idler on the conveyor, belt speed, loading rate, etc.)?
We're conveying iron ore at about 10,000t/hr, and use steel cord belt.
Cheers,
Tom ■