fjalali
70 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:

11.0  

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:

8.0  

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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Lafecapo
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

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lalbatros
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,
    circulating load, ....
  • 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.docentes.utonet.edu.bo/njacintoe/wp-content/uploads/Grinding_Fundamentals.pdf

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

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Vikpro
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 partition1
First comp. Length ( effect)     Mts.2.3
First Comp. Useful Mill Dia. Mts3.23
Second comp. length ( effect) Mts.8
Second Cmp.Useful Mill Dia. Mts3.27
Third comp. length ( effect)    Mts.0
Third Comp. Useful Mill Dia. Mts0
Mill RPM17.2
Size in microns, 80% of mill feed pass F11000
Bond's works index of mill feed, size  Wi13.49
Specific gravity of mill feed.    S3.09
Volume of first Comp.   M318.84
Power demand cal. 1st Comp399
Volume of second Comp.M367.15
Power demand cal. 2nd Comp1389
Volume of third Comp.M30
Power demand cal. 3rd Comp0
Power demand  total.  Kw ( Aprox)1824
Useful Mill Length                Mts10.3
Material retaintion time min6.3
Mill Critical Speed 23.54
Mill speed of critical speed %73.07
First compartment
% of filling first compartment32.7%
Grinding Area of first Comp. %21.9%
Compartment Volume  M318.8M3
Total Bulk Weight of balls28.5tons
Bulk density of all balls.4.631t /d m3
Bulk Volume6.2M3
Total Numbers of Balls34559#s
Nos. Of ball impact/ revolution.61861Impacts
Nos of Ball impact / sec17733Impacts
Material retaintion time ( min )1.41min
Average Ball Weight0.8kg
Ball Surface/Comp. Volume Ratio27.1 
Second compartment
% of filling second compartment29.8%
Grinding Area of second Comp. %78.1 
Compartment Volume  M367.15m3
Total Bulk Weight of Balls98.0tons
Bulk density of balls.4.89t / dm3
Bulk Volume20.03m3
Total Numbers of Balls3564486#s
Nos. Of ball impact / revolution.6380430Impacts
Nos of Ball impact / sec1829057Impacts
Material retaintion time ( min )4.89min
Average Ball Weight0.027kg
Ball Surface/Comp. Volume Ratio80.0 

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