1156 posts
TimePosted 22/08/2006 10:21:15

Crushing Question 1

What should be the standard sieve sizes for limestone feeding to Vertical roller mill. We were earlier using Limestone having bond index of 8-9kWh/short tonne. Now we are having limestone with bond index 11-14kWh/ short tonne. Wether any reduction in mill feed size will improve the output of the rawmill. How to calculate finess modulus of crushed limestone and what is the optimum value for VRM.

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1156 posts
TimePosted 22/08/2006 10:21:15

Re: Crushing

Yes, reducing the size of the feed to the raw mill should result in an increase in output. Bond's equations use the size grading where 80 per cent of the feed is passing to characterise the size of the feed to the mill. The optimum size of mill feed is related to the nip angle between the rollers and table. 60mm is quoted as the maximum size.

1156 posts
TimePosted 22/08/2006 10:21:15

Crushing Question 2

Why does false air infiltration from the bottom stage of a preheater tower increase tower temperature, but in top stage decrease the tower temperature. The preheater system is SLC-S supplied by Fuller. We understand this is a common phenomenon for any other system like ILC, SLC or SLC.

1156 posts
TimePosted 22/08/2006 10:21:15