Grinding & Classification Circuits

Grinding & Classification Circuits

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Air Classification (1 reply and 3 comments)

S
Saghar
4 years ago
Saghar 4 years ago
Hello, I am working on air classification operations in a cement plant. The final air classifiers (High efficiency type, manufactured by polysius) have high values of bypass, let's say around 40%. I wanted to know what are common practices to reduce the bypass value of a high efficiency air classifier in cement plant?
What are the causes of bypass being high? Can fineness of the classifier feed be a reason?
Mike
4 years ago
Mike 4 years ago
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First off you need to understand what "high" efficiency in an air classifier actually is, and it is not all that high.  Your 40% bypass could be classed as "high" efficiency based on the size distribution of the feed material and the design characteristics of the classifier. If your feed conditions (distribution, and rate) do not match the design conditions very closely your result will be different from expected.  Particularly if you have a lot more material at or near the desired cut point.

You need to take the performance curves for the classifier at design conditions and then compare that to actual conditions.  The curves should be a set based on several different sizes.  

S
Saghar
4 years ago

Thank you very much for answering
efficiency curves are achieved using size distribution of the feed, overflow and underflow. cut size is approximately 8.

Mike
4 years ago

Usually the first step is to reduce the feed rate to the classifier to see if this helps. So what is the feed rate you are sending to the classifier. What is the classifiers designed feed rate. A lot more is needed.

Commonly the first step would be to conduct a performance test and compare actual conditions to what it was designed for. This can then determine if the classifier is to small for the job or if the grinding stage ahead is not performing correctly.

S
Saghar
4 years ago

That was very useful. Thanks
I will declare the results if I can change the feed rate of the classifier

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