Bond index for "fine" ore and different sieve size - Grinding & Classification Circuits - Metallurgist & Mineral Processing Engineer

To participate in the 911Metallurgist Forums, be sure to JOIN & LOGIN
Use Add New Topic to ask a New Question/Discussion about Grinding.
OR Select a Topic that Interests you.
Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

← Back to Grinding & Classification Circuits...

Bond index for "fine" ore and different sieve size (1 reply and 1 comment)

rakavka

9 months ago

rakavka 9 months ago

Hi guys,

I have to calculate a new throughput of the existing grinding circuit with a new finer ore.

I'm trying to calculate a BM working index of the new ore with 300 um sieve size.

The problem is that amount of undersize in feed is higher then 250% circulating load (CR) so I get negative mill revolution.

I've though of some solutions:

To decrease the sieve size and get probably a higher work index.
Decrease a CR to say 150%.
Remove part of -300um from testing ore in first run (?)

What should I do? Is there a better solution?

Also, if I change a sieve size tested from 150 to 300um, is there anything I need to change in specific energy consumption eq.?

Thanks in advance

Alex Doll

9 months ago

Alex Doll 9 months ago

1 like by rakavka

Hi Rakavka

Yes, you should screen the 300 µm out of the feed to the first cycle to get the test started, but the make-up feed to the remaining cycles should not be pre-screened.

You should run two tests, one with the 300 µm closing screen and the second with the 150 µm closing screen. I expect the 300 µm result will be significantly higher Wi than the 150 µm result.

It is a good idea to make sure that your feed is properly prepared since I do not run into this problem very often. The feed should have been stage-crushed down to 100% passing 3.36 mm and it should approximate a Gaudin-Schuhmann particle size distribution (use https://granulometrics.com/ to check the PSD regression models). If the PSD deviates significantly from the G-S model, you might have a feed that isn't suitable for performing the test.

-AD

https://www.sagmilling.com/

rakavka

8 months ago

Hi Alex,
I eventually used Magdalinovic rapid method which by-passes the fines problem. Isn't it opposite? the smaller the sieve, the higher Wi? For a finer product we need to put more energy..?
Thanks in advance
Rakavka

Please join and login to participate and leave a comment.