Crushing, Screening & Conveying

Crushing, Screening & Conveying2017-04-04T06:57:13-04:00
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Removal of Scrap Metal in Gyratory Crushers (4 replies and 1 comment)

Eder Figueiredo
2 years ago
Eder Figueiredo 2 years ago

Hi Everybody,

I have seen many people get injured seriously during activities regarding the removal of the scrap metal such as excavator and loader teeth, drill bits in crushers. The major risks are sliding material and flying metal during cutting.

The common procedure is lock out and tag the crusher, clean the crushing chamber, relief the mainshaft hydraulic pressure and cut using oxy flame or welding torch. In many situations, this procedure is not suitable for a safe activity and leads to serious injuries.

Does anybody know any device for removal the scrap metal in a gyratory crusher or a safer practice without exposure of people or avoid accessing the crushing chamber?

Meanwhile, we are working in order to develop a scanning or detection technology to detect the scrap metal in the back of the truck before its dumping into the crusher.

Regards,

Craig Lockhart
2 years ago
Craig Lockhart 2 years ago
1 like by David

Greetings Eder...welcome to 911,

Unfortunately, your comments are entirely valid and I know of no methods for removing lodged metal from a crusher that are inherently safe.  The methods you described are common and there may be ways and tools that can make the job safer, but most of the operations at which I have worked have been focusing on prevention.  

Some manufacturers offer electronic monitoring to detect when a tooth, adapter,shroud, lip, or liner plate, becomes detached from the bucket or blade - as soon as the lost tool is detected, any load that may contain the metal can be diverted to waste, leach, or perhaps dumped on the ground to search and retrieve the piece.  Check: http://www.motionmetrics.com

Additional precautions can be implemented for maintenance activity - maintenance personnel should be required to prove that they installed all parts they packed into the mine and packed all of the replaced/worn/broken parts out.  And, the reasons for doing this need to be communicated in the strongest possible terms.

If prevention is ineffective and metal is lodged in your crusher, you can mitigate the risks of cutting by using cutting tools with long reach (e.g. thermic lance) to put distance between the operator and the hazard.  

I believe cutting from below is the less dangerous work position, provided all required lockouts are performed, muck in the surge chamber and dump pocket is stabilized, muck overhead is properly scaled, and the lodged metal can be accessed with minimal danger.  Lodged metal in a crusher always releases upward, so keep people well clear of the dump pocket when cutting.

Be careful not to release too much fluid from the hydroset - most crushers will be jammed too tight for the mantle to drop/release the metal and when the cutting finally relieves the jam, the mantle can drop violently and damage the hydroset or other internal components.  This could also cause a "seismic" event and destabilize overhead materials.

Be safe...

Eder Figueiredo
2 years ago

Thanks Craig.
I really appreciated your comments. They will be very useful to me.
Stay safe as well.

Master Q
2 years ago
Master Q 2 years ago

I have no experience with this but if access to the jammed metal is possible then packing it with a bit of Thermite could be of use. Would need to be careful as you don't want to weld/fuse any metal and don't want still reacting dropouts landing on anything below. If you are able to just for a very short period of time soften the lodged piece it could deform to release the tension. Just a thought.

Nurettin
2 years ago
Nurettin 2 years ago

One time I had knowledge.

we tie the teeth with the thick rope of crane. With the crane we stressed the teeth a little. At the same time we moved main shaft a little down with the help of hydrolic jacks.

heating, cooling or cutting can be dangerous. 

I am thinking a hydrolik clamp mover. It can be installed to excavator. 

Eder Figueiredo
2 years ago
Eder Figueiredo 2 years ago

Nurettin and Master Q,
Thanks for your comments,

I fully agree with you. Any human interaction during this activity can be very dangerous.

Frequently the mainshaft of the crusher keeps jammed too tight (we cannot move it up or down ). Then, there is a high residual pressure which can violently release the piece of metal upwards.

For small conic crushers, we have been successful. Our procedure is to loosen up the spider bolts and lift the spider shell a little bit (around 15 mm). Then, we may release the hydraulic pressure and remove the scrap metal in a faster, easier and safer manner.

Unfortunately, for the big crushers specially gyratory crushers “We cannot see the light at the end of the tunnel yet”.

The idea of installing a clamper mover to the excavator is great.

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