Mill Residence Time

Hello everyone,

What is an effective method to properly measure the residence time of material in a ball mill?

Thanks

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re Mill Residence Time

Hello Shastri,

A common method is to add ~20kg of flourescent dye to the mill feed, record the exact time, and then collect raw meal samples at timed intervals of 30secs at a location near the exit of the mill.

About 10g of each sample is shaken with 50ml of water and filtered in the laboratory (or allowed to settle until the supernatant liquid is clear). The time to the point where the colour intensity of the dye is the strongest is the residence time.

Some dyes are able to be seen with the naked eye, while others are best viewed with a "black" light or UV light. Testing the filtered liquid samples using a UV spectrophotometer is even better.

Regards,

Ted.

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re Mill Residence Time

Thanks alot. Well definitely try.

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re Mill Residence Time

Hello Shastri,

I should have also mentioned that the flourescent dye should be water soluble.  Flourescein sodium salt is typically used;-

http://www.sigmaaldrich.com/catalog/product/sial/f6377?lang=en&region=AU

Regards,

Ted.

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