Grinding & Classification Circuits

Grinding & Classification Circuits

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Rod mill rods wear (2 replies and 5 comments)

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ritwik117
6 years ago
ritwik117 6 years ago

In a rod mill of diameter 3.8m I have three types of rod size distribution like 100 mm ,85mm ,70mm.In petcoke operation the vendor suggest that the wear rate is 52gms per ton of dry petcoke charged. I want to know the wear rate of individual rods like (100mm or 85mm or 70 mm) or in other language I want to know after how many days 100mm rods become 70 mm?  How the wear rate will be divided in the rod size distribution?

I need help on this topic. It will be very much helpful for me.

Mike
6 years ago
Mike 6 years ago
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1 like by David

Based on the information supplied it is difficult to answer, but here is an approximation. 

Assume rods are 8 gms/cc (approximate density of cast iron), that gives a 100 mm rod is approximately 63,000 gms/meter of length (you did not supply the length of your rods or mill), an 85 mm rod is approximately 45,000 gm/meter of length, and a 70 mm rod is approximately 31,000 gms/meter of length. This means that a 70 mm rod is about half a 100 mm rod. So you need to wear 32,000 gms for every meter which works out to 600 tonnes of petcoke. Of course wear is not even, and the center sees more wear, also this needs to be factored to the number of rods of each size (which you did not say).

The big factor here is that before the 100 mm rods will reach 70 mm, the 70 mm will probably be broken and you need to have removed them before then. The sight of a rod mill with some broken rods twisted around the load and jamming things together is sight to behold. Also the amount of time and labor to go in and cut the mess free and clean it up is huge.

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ritwik117
6 years ago

Sir,
Rod length is 5.2 mtr.and sir I have a doubt that surface area of 100 mm rods is greater than 70 mm rods.so more material will be in contact with 100 mm rods than 70 mm.so I hope the wear rate in 100 mm rods is greater and for information the rod size is distributed in 25%,50% and 25% ratio.so I want to know the wear rate distribution among the rods.
Thank you for your time

Mike
6 years ago

I did not say that the 70 mm rods will have a greater surface area, but rather that the wear on the 70 mm rods will cause issues before the 100 mm will be worn to 70 mm, Actually more material will be in contact with the 70 mm rods than the 100 mm. This is due to packing factors where the larger pieces will hold the larger rods apart and fill the voids around the smaller rods. The wear rate of the 70 mm will be the greatest, followed by the 85 mm and then the 100 mm.

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ritwik117
6 years ago

Thank you smart dog for your awesome reply. Smartdog please give me some link to know about packing factor.

Mike
6 years ago

Probably the best examples are from time management but use the basic principles see:

https://www.youtube.com/watch?v=v5ZvL4as2y0

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ianvallecera
6 years ago
ianvallecera 6 years ago
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Hi, I’m sorry this will probobly be no use. To add up what mr. Smartdog had said, I think it will also depends on the type of material you used in the rods. And you should also consider the revolution or mill speed. This is an internal investigation and I hope this will help on where to look first.

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ritwik117
6 years ago

Hi,for your information,Its cast iron material .Material density 7.85 ton/m3.Mill speed 14.5 rpm.If you need more data or information about that please comment here. But please help me on that matter.

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