Grinding & Classification Circuits

Grinding & Classification Circuits 2017-04-04T06:57:16+00:00
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Classifying Liners (5 replies and 2 comments)

David Kano
2 years ago
David Kano 2 years ago

I'm faced with contradictory claims concerning classifying liner regarding their effectiveness, energy efficiency or applicability for high tonnage or hard/abrasive ores. Litterature is really scarce on this subject.

Classifying liners are a kind of ball mill liners who's main role besides providing shell protection and charge motion is to induce a longitudinal balls segregation of the charge based on their size. In short they classify the balls from large feed end to small ones discharge end. This is an old idea as some patents date back to 1958 but they are mainly used in clinker grinding.

My basic question is : Some, including manufacturers of these classifying liners, claim that these liners are very effective for energy efficiency. Others say they do not work. And for the most part none of the two sides gives sound evidence of their claims or back them with detailed studies.

So my question : Does anyone in the here know of some sound and balanced reference on the matter ?
Has anyone tried them and compared them with classical liners and could share his experience?

As for those who question explicitly the efficiency of the technology based on "experimental/industrial" survey there is conference paper by the (then?) Milling Manager of FLSmidht back in 2006[2]. In particular there we one can find a table comparing the specific power consumption (for the same blaine) of "straight" liners and "classifying" liners. Surprisingly the study concludes to the disadvantage of these later.
I cite this reference because it is the only one I've found presenting this kind of comparative analysis., Even though, for one, the same manufacturer propose these type of liners in his portfolio [3]. And second, I've never found any citation of this reference which is unusual for the least for a paper backed by industrial comparative survey. And last the main objective of the study-paper was to promote FLSmidth HES system as a better solution than classifying liners.

Back to those who promote this technology : an online leaflet (Vega) advances figures comparing an old second chamber liner (Dragpeb) with their classifying liners. Here they get/claims great achievement. To note that Dragpeb were Tile-type liners FLSmidth used to promote. They no longer make them I guess as a search for Dragpeb in their site gives no result. These are in a scare form with wavy thin oblique valley. So I suppose that if they were clock-turned on the wrong side they sure will classify in the wrong direction. So the finding/claim of Vega could be no such a surprise if it was the case in the original mill. I purely speculate here but let me share with you this "funny exchange" in a site for cement industry. I guess finishing the week with a smile will not be a bad idea:

Some ball mills around there are really a black box.

[1]Ball motion, axial segregation and power consumption in a full scale two
chamber cement mill, Minerals Engineering 22 (2009) 809–820
[2]Ball charge loading - impact of specific power consumption

Alan Carter
2 years ago
Alan Carter 2 years ago

There is very little literature on the subject as you mentioned.
The object of classifying liners is to keep coarser balls in one section and smaller in the other section. So basically you want high impact energy in one section and lower in the other section. To avoid using classifying liners in the mill but achieving the same objective, I have conducted testwork where I have "graded" the lifter profile angle. My laboratory mill had 4 sections and I could modify the lifter angle for each section. At the feed I have used higher lifter profile angle say 75 degree and graded the angle to reach 45 in the last section. The preliminary results coupled with DEM simulations were good.

Maya Rothman
2 years ago
Maya Rothman 2 years ago

Look for Angular Spiral Lining (ASL) . There is some literature about it.

Bob Mathias
2 years ago
Bob Mathias 2 years ago
Victor Bergman
2 years ago

They are basically for multiple-chamber mills. Am I right? Like what usually used in Cement?

Bob Mathias
2 years ago

Not really, my experience with them was in copper with two types (ASL and AMB) ASL reduced the volume of the mill and AMB was a rubber one with lifters of different heights simulating the effect of classification installed indifferent places and different rows. Both of them were applied to one chamber - grate discharge mills. AMB means Alto (high) Medio (Medium) Bajo (Low) related to lifters height.

David Kano
2 years ago
David Kano 2 years ago

Thanks everyone,

Many valuable comments and feeds here.
I'll check ASL and AMB when I'll be back to my office, and if I need something more specific about them I'll contact you, dear Kelly. As for Magotteaux products I already had a look to the website I know their products. We've met one guy last year and we've got a good exchange on the ability of our 3D-DEM simulation software and it's Mill Model version for ball charge optimization. And here came this subject classifying liners. Besides their efficiency, at the time we are speaking, I do not know of any other software (3D-DEM modeling) able to address and simulate (and later on optimize) an industrial or even a pilote Mill equipped with classifying liners. I mean able to predict the long term classification of ball (and rocks) inside the mill. Cleary addressed in his the short term classification and we are trying to check who can do it who could be interested by it.

2 years ago
David 2 years ago

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