81 posts
TimePosted 15/06/2011 10:36:15
fjalali says

### Request for feedback for a Two Chamber Cement Mill Ball Charge and Longitudinal Sieve Analysis

I am looking to get feedback for the following cement mill for a white cement plant.  The first compartment has lifting liners and the second compartment has lifting at the beginning followed by classifying liner. The mill dimension is as follows:

 Mill Diameter: 3.4 m Mill Length: 11 m First Chamber Effective Diameter: 3.23 m First Chamber Effective Length: 2.3 m Second Chamber Effective Diameter: 3.27 m Second Chamber Effective Length: 8 m

Input clinker sieve analysis:

 mm Clk 25.40 1.90% 19.00 3.50% 12.70 10.10% 9.50 19.50% 8.00 - 6.35 45.10% 4.76 63.40% 2.38 85.30% 1.19 94.60% 0.84 97.40% 0.60 98.10%

And the existing ball charge design:

 First Chamber Ball Charge Ø  Ball  [mm] Weight  [ t ] Percent  [%] 90 6.5 23 80 8.0 29 70 5.8 21 60 5.9 21 50 1.8 6 Total: 28 100 Average ball weight [ g ] 1665 Spec. media surface [m2 / t] 9.7 Volume Load [%] 34.0 Second Chamber Ball Ø  Ball  [mm] Weight  [ t ] Percent  [%] 50 8 8 40 7 7 30 6 6 25 22 22 20 55 56 Total: 98 100 Average ball weight [ g ] 46 Spec. media surface [m2 / t] 32.7 Volume Load [%] 31.3

The longitudinal sieve analysis is as follow:

Using the Clk sieve analysis I calculated that the maximum ball required will be:

 INPUTS: (Input Shaded Area Values) Wi = 13.49 s = 3.09 D80 = 11000.00 D = 3.22 Mill Speed 17.20 K= 335.00 Calculated Values: Critical Speed = 23.57 Pc = 72.97

Can you please tell me your opinion the mill charge composition and longitudinal analysis?

Should the mill feeling degree be decreased? What about the max ball used?

How can we increase production in this mill?

I appreciate all your comments and feedback.

Thx

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5 posts
TimePosted 15/06/2011 12:44:01
Lafecapo says

### Re: Request for feedback for a Two Chamber Cement Mill Ball Charge and Longitudinal Sieve Analysis

Dear Fjalali:can you send us your email in order we can get the excel sheets to do a better analysis. Then we can answer you here in the forum.

Have a great day.

Ariel

138 posts
TimePosted 16/06/2011 07:17:07
lalbatros says

### Re: Request for feedback for a Two Chamber Cement Mill Ball Charge and Longitudinal Sieve Analysis

fjalali,

When editing your post, you can add attachments. Excel files with your data as well as drawing would be useful. You can do that using the option tab. The upload popup screen is cluttered with advertising and looks a bit crazy, but it works. Attaching files could be very useful. Large table are difficult to read on this forum, again because too much space of the screen is reserved for advertising.

Concerning you question, these additional information could be useful:

• is it an open-circuit ball mill or a closed-cicuit?
• are you using steel balls or ceramic balls?
(could be ceramic sometimes for white cement)
• are you producing one main product or
are you producing several different products?
• eventually, what kind of separator is being used?
how does the separation curve looks like,
how much is the bypass ratio,
• what is the (main) product being produced?
what are the raw materials and the recipe?
what is the fineness of the cement
particle size distribution of the cement, ...
• are you using grinding aids?
• what are the temperatures in the grinding circuit?
• if it is a closed circuit, could you provide the
particle size distribution of the separator feed, reject, product?
• what is the current power consumption and hourly production
and what is the current rotation speed?
• It could be also useful to explain the symbols you are using!
Is D80 related to the feed or the product?
Some people write P80 when it is the product and F80 for the feed !
What do you mean by Pc, for example?
What are s or K?
Also show all the units in your data, I guess D80 is in µm?
What do you call "critical speed", and what are the units?
• Would should also provide the formulas you are using.
Attaching an Excel file would be the easiest way.

Thanks,

Michel

Maybe you could enjoy reading this:

http://www.mineraltech.com/MODSIM/ModsimTraining/Module6/Grinding.pdf

http://www.fivesgroup.com/FivesFcb/EN/Expertise/Documents/Grinding%20plants-Optimization%20and%20modelling.pdf

www.smartdogmining.com/tools/SDM%20Mill%20Calcs.xls

www.uc.cl/sw_educ/simula/excel/Ballsim_Direct.xls

77 posts
TimePosted 17/06/2011 12:36:35
Vikpro says

### Re: Request for feedback for a Two Chamber Cement Mill Ball Charge and Longitudinal Sieve Analysis

As per your given mill details.(mill output assumed to be 45 tons / hr) for more details you can contact me at  vikprocem@gmail.com

It is not so easy to understand the cement plant without being present at site. But, still according to my calculations-

- The size of your first chamber grinding media seems to be more.

- Max ball size should be upto 70 mm

Data Entry  - Yellow cell

 VIK-promill Data Entry Mill tube Length                 Mts. 11.00 Mill tube Dia.                      Mts. 3.4 Mill liner size                      Mts. 0.14 Partition Wall size              Mts. 0.7 Nos of partition 1 First comp. Length ( effect)     Mts. 2.3 First Comp. Useful Mill Dia. Mts 3.23 Second comp. length ( effect) Mts. 8 Second Cmp.Useful Mill Dia. Mts 3.27 Third comp. length ( effect)    Mts. 0 Third Comp. Useful Mill Dia. Mts 0 Mill RPM 17.2 Size in microns, 80% of mill feed pass F 11000 Bond's works index of mill feed, size  Wi 13.49 Specific gravity of mill feed.    S 3.09 Volume of first Comp.   M3 18.84 Power demand cal. 1st Comp 399 Volume of second Comp.M3 67.15 Power demand cal. 2nd Comp 1389 Volume of third Comp.M3 0 Power demand cal. 3rd Comp 0 Power demand  total.  Kw ( Aprox) 1824 Useful Mill Length                Mts 10.3 Material retaintion time min 6.3 Mill Critical Speed 23.54 Mill speed of critical speed % 73.07 First compartment % of filling first compartment 32.7 % Grinding Area of first Comp. % 21.9 % Compartment Volume  M3 18.8 M3 Total Bulk Weight of balls 28.5 tons Bulk density of all balls. 4.631 t /d m3 Bulk Volume 6.2 M3 Total Numbers of Balls 34559 #s Nos. Of ball impact/ revolution. 61861 Impacts Nos of Ball impact / sec 17733 Impacts Material retaintion time ( min ) 1.41 min Average Ball Weight 0.8 kg Ball Surface/Comp. Volume Ratio 27.1 Second compartment % of filling second compartment 29.8 % Grinding Area of second Comp. % 78.1 Compartment Volume  M3 67.15 m3 Total Bulk Weight of Balls 98.0 tons Bulk density of balls. 4.89 t / dm3 Bulk Volume 20.03 m3 Total Numbers of Balls 3564486 #s Nos. Of ball impact / revolution. 6380430 Impacts Nos of Ball impact / sec 1829057 Impacts Material retaintion time ( min ) 4.89 min Average Ball Weight 0.027 kg Ball Surface/Comp. Volume Ratio 80.0