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EXAMPLE 22 – Comminution

FLOWSHEET DATA NO OPR UNIT PROCESS IS1 IS2 IS3 IS4 IS5 IS6 INV OS1 OS2 OS3 OS4 OS5 OS6 1 SEC COMMINUTION 0 0 0 0 0 0 0 0 0 0 0 0 0 2 SCR GRIZZLY 1 0 0 0 0 0 0 2 3 0 0 0 0 3 CRJ JAW 3 0 0 0 0 0 0 4 0 0 0 0 0 4 CVB CONVEYOR 2 4 0 0 0 0 0 5 0 0 0 0 0 5 SCR DOUBLE DECK 5 0 0 0 0 0 0 6 7 8 0 0 0 6 CRC CONE 7 8 0 0 0 0 0 9 0 0 0 0 0 7 SCR DOUBLE DECK 6 9 13 0 0 0 0 10 11 12 0 0 0 8 CRC CONE 11 12 0 0 0 0 0 13 0 0 0 0 0 9 MLB BALL MILL 10 14 18 0 0 0 0 15 0 0 0 0 0 10 SMP 15 16 0 0 0 0 0 17 0 0 0 0 0 11 CYH CYCLONE 17 0 0 0 0 0 0 19 18 0 0 0 0

Cummulative Fraction Passing Data

17.00 IN 1.0 12.00 IN 0.98 8.48 IN 0.85 6.00 IN 0.68 4.24 IN 0.48 3.00 IN 0.37 2.12 IN 0.26 1.50 IN 0.20 1.05 IN 0.14 0.742 IN 0.11 0.525 IN 0.08 0.371 IN 0.06 3 TY 0.04 2000 TY 0.00001

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COMMINUTION EXAMPLE The design of the circuit is to achieve a product of 110 microns. Process Data The components required are SiO2 (Quartz) Solid and H2O aqueous. Stream 1 - The Feed flowrate is 400 mt/hr and contains 95% solids. Stream 14 - Ball mill make-up water. Initially estimated as 10 mt/hr. This flowrate will be adjusted by a percent solids controller, PSC, on the ball mill unit operation, maintaining 68% solids. Stream 16 - Cyclone make-up water. Initially estimated as 10 mt/hr. This flowrate will be adjusted by a percent solids controller to maintain 55% solids.

Percent Solids Controls

CN ID OP SN PS

1001 MLB 68% Solids 9 14 0.68

1002 CYH 55% Solids 11 16 0.55

User Created Objects

Scaler Name ID Value

USMLBRATIO MLB L-WR 1.25

Then click the Ball Mill unit operation with the Edit Object Data Tool & in the Controls CtA field enter

USMLBRATIO„(IL+0)÷ID

IL is the Ball Mill Length Inside Liners ID is the Ball Mill Diameter Inside Liners

Now add the following Stream Graphic Boxes, remembering there is already an EXAMPLE in the List

window of the Stream Graphics Boxes and this is Box number 1.

Stream Graphic Boxes - Add the following Stream Graphics Boxes.

Box No 2 Box No 3 Box No 4

BX Outputs Cyclone Ball Mill

CW 6 6

L1 SN SN SN

F1 S S S

L2 SI Mt/Hr SI Mt/Hr SI Mt/Hr

F2 SI VCWT S SI VCWT S SI VCWT S

L3 LI Mt/Hr LI Mt/Hr LI Mt/Hr

F3 LI VCWT S LI VCWT S LI VCWT S

L4 % Solids % Solids % Solids

F4 100 ×VPCS S 100 ×VPCS S 100 ×VPCS S

L5 P80 P80 P80

F5 VP80 S VP80 S VP80 S

L6 No CYH No. MLBs

F6 'NO' VFLS u11 'NO' VFLS u9

L7 Dia CYH INCHES DIA INSIDE LINERS

F7 'DC' VFLS u11 'ID' VFLS u9

L8 CYH PRESS Length INSIDE LINERS

F8 'PR' VFLS u11 'IL' VFLS u9

L9 % CIRC LOAD MLB L TO W RATIO

F9 100×(SI VCWT s18)÷SI VCWT s19 USMLBRATIO

All Streams Stream 19 Stream 15

Except 15 & 19

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From the results it will be noticed the cyclone overflow did not meet the requirements of 80% passing 110

microns. A feedback controller will now be applied to adjust the cyclone feed stream percent solids to

achieve the required micron size.

Feedback Control CN OP NO SN OV LV HV VF SP SL ID

1003 11 10 0 0.55 0.5 0.6 VP80 s19 110 1 Control % Solids so P80=110

The Feedback Controller above will adjust the Percent Solids Controller 1002 until a P80 of 110 microns is

achieved in stream 19.

Percent Solids Control

For the Feedback Control to adjust the Percent Solids Control the following changes must be made to the

Percent Solids Control 1002.

The PS variable in PSC controller 1002 should be change to;

VCTL 1003

The model may be calculated again. The feedback controller adjusts the percent solids of the cyclone feed

until the desired product size of 110 microns is achieved in stream 19.

Unit Operation Data

All of the Input Data for the Unit Operations can be found on the diagram.

How The Flowsheet Is Calculated.

1. Calculate the Current Section.

2. After Calculating select to Edit the Ball Mill and then select the Dimensions Window.

The Ball Mill is setup initially with Calculation Option 2 - P80. The variable P8 is set at 110 microns

which is our target and the Diameter Of The Inside Liners, ID, is set at 15.5 feet. After Calculating

METSIM will predict the Inside Liners Length, IL. In this example 39.45928869 feet. 15.5 x 39.5 is too

long for a Ball Mill so we go to the to the Ball Mill Window of the Unit Operation data and change the

Number of Ball Mills, NO, to 2.

Now Calculate just the Ball Mill. Then go back to the Dimensions Window in the Ball Mill Unit Operation

Data and look at the value for IL. It should now be 19.72964435. The Mill Ratio for this is 1.375 = 15.5 x

19.75. So to set METSIM to use this size change the CO option to 1-Bond Inside Length so that METSIM

will now use the IL in the Calculation instead of the P8, P80, value.

Next Calculate the Flowsheet. Notice in the results that 10 Cyclones were predicted but the P80 value was

a little low at 104 microns.

A feedback controller will now be applied to adjust the cyclone feed stream percent solids to achieve the

required micron size.

Feedback Control CN OP NO SN OV LV HV VF SP SL ID

1003 11 10 0 0.55 0.5 0.6 VP80 s19 110 1 Control % Solids so P80=110

The Feedback Controller above will adjust the Percent Solids Controller 1002 until a P80 of 110 microns is

achieved in stream 19.

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Percent Solids Control

For the Feedback Control to adjust the Percent Solids Control the following changes must be made to the

Percent Solids Control 1002.

The PS variable in PSC controller 1002 should be change to;

VCTL 1003

The model may be calculated again. The feedback controller adjusts the percent solids of the cyclone feed

until the desired product size of 110 microns is achieved in stream 19.

The Cyclone achieves 110 microns in stream 19 but only 9 Cyclones have been predicted. As an equal

number of Cyclones are required for 2 Ball Mills it will be necessary to change the IL .

Set the IL variable in the Ball Mill to 19.5 and Calculate.

Still only 9 Cyclones predicted so set the IL variable in the Ball Mill to 19.25 and Calculate.

Now METSIM Predicts 10 Cyclones at a pressure inside our range for the Cyclone.

RESULTS NO. STREAM MT/HR-SI MT/HR-LI MT/HR-TC ---+--- +--------+--------+-------- 1 1 380.000 20.000 400.000 2 2 242.449 12.760 255.210 3 3 137.551 7.240 144.790 4 4 137.551 7.240 144.790 5 5 380.000 20.000 400.000 6 6 126.013 6.632 132.645 7 7 111.292 5.857 117.149 8 8 142.695 7.510 150.206 9 9 253.987 13.368 267.355 10 10 380.000 20.000 400.000 11 11 172.922 9.101 182.023 12 12 243.849 12.834 256.683 13 13 416.771 21.935 438.706 14 14 0.000 237.547 237.547 15 15 2253.630 1060.532 3314.162 16 16 0.000 708.939 708.939 17 17 2253.630 1769.471 4023.101 18 18 1875.364 803.725 2679.089 19 19 378.267 965.746 1344.013

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Comminution Example SCREEN SIZE ANALYSIS STREAM NO. 1 STREAM NO. 10 STREAM NO. 15 1 10 15 P80= 194554 P80= 9941 P80= 795 ---------------- -------------------- -------------------- -------------------- SCREENS MICRON MT/HR % RET % PAS MT/HR % RET % PAS MT/HR % RET % PAS ---------------- -------------------- -------------------- -------------------- 12.0 IN 304800 7.600 2.000 98.00 0.00 0.000 100.00 0.00 0.000 100.00 8.48 IN 215392 49.400 13.000 85.00 0.00 0.000 100.00 0.00 0.000 100.00 6.00 IN 152400 64.600 17.000 68.00 0.00 0.000 100.00 0.00 0.000 100.00 4.24 IN 107696 76.000 20.000 48.00 0.00 0.000 100.00 0.00 0.000 100.00 3.00 IN 76200 41.800 11.000 37.00 0.00 0.000 100.00 0.00 0.000 100.00 2.12 IN 53848 41.800 11.000 26.00 0.00 0.000 100.00 0.00 0.000 100.00 1.50 IN 38100 22.800 6.000 20.00 0.00 0.000 100.00 0.00 0.000 100.00 1.05 IN 26670 22.800 6.000 14.00 0.00 0.000 100.00 0.00 0.000 100.00 .742 IN 18847 11.400 3.000 11.00 0.00 0.000 100.00 0.00 0.000 100.00 .525 IN 13335 11.400 3.000 8.00 0.00 0.000 100.00 0.00 0.000 100.00 .371 IN 9423 7.601 2.000 6.00 89.86 23.647 76.35 0.00 0.000 100.00 3 TY 6730 7.599 2.000 4.00 103.46 27.226 49.13 10.13 0.449 99.55 4 TY 4760 0.765 0.201 3.80 58.59 15.419 33.71 24.05 1.067 98.48 6 TY 3360 0.769 0.202 3.60 29.65 7.803 25.91 39.46 1.751 96.73 8 TY 2380 0.761 0.200 3.40 15.30 4.027 21.88 56.95 2.527 94.21 10 TY 1680 0.769 0.202 3.19 11.84 3.115 18.76 76.42 3.391 90.81 14 TY 1190 0.761 0.200 2.99 10.60 2.790 15.97 97.06 4.307 86.51 20 TY 841 0.766 0.202 2.79 9.45 2.487 13.49 122.33 5.428 81.08 28 TY 595 0.764 0.201 2.59 8.36 2.201 11.29 150.57 6.681 74.40 35 TY 420 0.769 0.202 2.39 7.36 1.936 9.35 185.24 8.220 66.18 48 TY 297 0.765 0.201 2.19 6.41 1.688 7.66 223.51 9.918 56.26 65 TY 210 0.765 0.201 1.99 5.55 1.460 6.20 261.41 11.600 44.66 100 TY 149 0.758 0.199 1.79 4.74 1.248 4.96 243.15 10.789 33.87 150 TY 105 0.773 0.203 1.58 4.04 1.062 3.89 177.24 7.864 26.01 200 TY 74 0.772 0.203 1.38 3.39 0.891 3.00 131.00 5.813 20.19 270 TY 53 0.737 0.194 1.19 2.77 0.729 2.27 99.19 4.402 15.79 400 TY 37 0.793 0.209 0.98 2.32 0.611 1.66 85.27 3.784 12.01 600 TY 26 0.779 0.205 0.77 1.87 0.493 1.17 66.12 2.934 9.07 800 TY 19 0.692 0.182 0.59 1.43 0.376 0.79 46.66 2.071 7.00 1200 TY 13 0.838 0.220 0.37 1.28 0.338 0.46 43.65 1.937 5.07 1600 TY 9 0.812 0.214 0.16 1.04 0.274 0.18 31.85 1.413 3.65 2000 TY 7 0.593 0.156 0.00 0.69 0.181 0.00 82.35 3.654 0.00 STREAM NO. 17 STREAM NO. 18 STREAM NO. 19 17 18 19 P80= 795 P80= 973 P80= 110 ---------------- -------------------- -------------------- -------------------- SCREENS MICRON MT/HR % RET % PAS MT/HR % RET % PAS MT/HR % RET % PAS ---------------- -------------------- -------------------- -------------------- 3 TY 6730 10.13 0.449 99.55 10.13 0.540 99.46 0.000 0.000 100.00 4 TY 4760 24.05 1.067 98.48 24.05 1.282 98.18 0.000 0.000 100.00 6 TY 3360 39.46 1.751 96.73 39.46 2.104 96.07 0.000 0.000 100.00 8 TY 2380 56.95 2.527 94.21 56.95 3.037 93.04 0.000 0.000 100.00 10 TY 1680 76.42 3.391 90.81 76.42 4.075 88.96 0.000 0.000 100.00 14 TY 1190 97.06 4.307 86.51 97.06 5.175 83.79 0.000 0.000 100.00 20 TY 841 122.33 5.428 81.08 122.33 6.523 77.26 0.000 0.000 100.00 28 TY 595 150.57 6.681 74.40 150.57 8.029 69.23 0.000 0.000 100.00 35 TY 420 185.24 8.220 66.18 185.24 9.877 59.36 0.001 0.000 100.00 48 TY 297 223.51 9.918 56.26 223.37 11.911 47.45 0.136 0.036 99.96 65 TY 210 261.41 11.600 44.66 257.76 13.744 33.70 3.655 0.966 99.00 100 TY 149 243.15 10.789 33.87 217.14 11.579 22.12 26.011 6.876 92.12 150 TY 105 177.24 7.864 26.01 124.36 6.631 15.49 52.878 13.979 78.14 200 TY 74 131.00 5.813 20.19 74.08 3.950 11.54 56.919 15.047 63.09 270 TY 53 99.19 4.402 15.79 50.31 2.683 8.86 48.886 12.924 50.17 400 TY 37 85.27 3.784 12.01 41.09 2.191 6.67 44.182 11.680 38.49 600 TY 26 66.12 2.934 9.07 31.06 1.656 5.01 35.055 9.267 29.22 800 TY 19 46.66 2.071 7.00 21.65 1.154 3.86 25.015 6.613 22.61 1200 TY 13 43.65 1.937 5.07 20.10 1.072 2.78 23.552 6.226 16.38 1600 TY 9 31.85 1.413 3.65 14.59 0.778 2.01 17.257 4.562 11.82 2000 TY 7 82.35 3.654 0.00 37.64 2.007 0.00 44.719 11.822 0.00