Grinding & Classification Circuits

Grinding & Classification Circuits 2017-03-23T09:46:37+00:00
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Hammer mill for raw clay not delivering required grind size (2 replies)

joy1484
2 months ago
joy1484 2 months ago

We started our hammer mill (Williams mill) after doing several maintenance to solve some electric problems. The plan was to get in spec and then not make any adjustments and watch grind. With a starting grind of 76 (spec is 74-86) we let the mill go and over the next 2.5 hours we saw grind steadily drop. This seems to be accompanied by a reduction in feed to the mill, although even feeder speed was constant throughout. Mill amps trended down, airflow increased, Classifier DP fell.

We stopped feeders and poked even feeder chute to check for obstruction, did not find anything significant. Started up, but ran out of feed shortly after. On second restart the grind was 76 again, but a second sample 20 minutes later was 72. The operator increased feed rate by 1 at this time but did not see the expected increase in grind, and at that point we shut down.

The dropping feed to the mill is something confusing, there aren’t a lot of reasons this would happen. Charts appear to show this improved after restart, but the non-response of grind was puzzling.

 

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Peter J
2 months ago
Peter J 2 months ago

What type of Clay are you grinding: The description seems to suggest you have a "swelling clay"

Robert
2 months ago
Robert 2 months ago

Did material sit in the feed hopper/silo during maintenance shut? When you checked for obstructions did you check to see if flow from feed silo? 

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