COMMINUTION EXAMPLE 5303 – GRINDING

Grinding The following example demonstrates a simple grinding circuit with a ball mill with a re-circulating load. Fatal error troubleshooting will also be addressed. It has been written for users with Metsim experience.  Add the following components using DBAS: SOLIDS AQUEOUS GASSiO2 (quartz) H2O N2

O2H2O

In the Model Parameters, activate the Heat Balance and Particle Size Analysis modules. Change the units of mass to metric tonne and the units of time to hour.

When prompted, select ‘Yes’ to change the Mesh Sieve Series. Select the TYM Tyler Sieves and click ‘OK’ to use all of the default screen sizes. From the Input menu, select SSNI Screen Sieve Series for Data Entry. Remove all of the screens larger than 1.05 in and smaller than 100 TY.

Create the flowsheet as seen below, noting the order of the unit operations:

In stream 1, enter 510 MT/HR of SiO2. Also, enter 1 MT/HR of H2O and enter in 0.68 for the % solids. The SSA should also be entered as seen below.

Place 1 MT/HR of H2O in streams 20, 21, 22, and 23.

Open the first sump unit operation (2), set the Engineering Units to English, and select 1-Design for the Calculation Option. Enter in a residence time of 5 minutes. Place a PSC control on stream 21, check the box for ON, and enter the following parameters: ID-% Solids to No. 1 Cyclone; OP-2; SN-21; PS-0.55; CO-0; CM-0. Calculate the sump.

Open and close the pump (3) to set the default parameters and calculate the pump.

Open the first cyclone unit operation (4) and change the Engineering Units to English. Set the parameters as listed: DC-26; AI-33.8; DV-9; DA-5; HT-78; SL-20; PS-0.7; RP[1]-8; RP[2]-12. In the Model Parameters tab of the same unit operation, select 1-Krebs as the Calculation Option and set the AA parameter to 4. Calculate the cyclone.

Open the ball mill and change the Engineering Units to English. Set the following dimensions: CO-Bond Inside length; ID-18.5; IL-24.5; CS-0.682; VP-0.45; BD-1.5. Also, set the following parameters: NF-4; WI-10.9; PF-1; OF-1.2; BE-1.

Place a PSC on stream 22 to set the percent solids in the ball mill to 68.5%. Calculate the ball mill.

Open the second sump (6) and change the Engineering Units to English. Also, set the Calculation Option to Design and enter a residence time of 3 minutes. Calculate the sump.

Open the second cyclone unit operation (7) and change the Engineering Units to English. Set the dimensions as listed: DC-26; AI-45; DV-8.5; DA-5; HT-78; SL-20; PS-0.7; RP[1]-8; RP[2]-12. The Calculation Option should be set to Krebs.

Place a PSC on stream 23 with the following parameters: CN-3; OP-6; SN-23; PS-VCTL 4. Place a FBC near the second cyclone unit operation (7) with the following parameters: CN-4; OP-7; NO-6; SN-0; LV-0.3; HV-0.7; VF-VP80 s9; SP-170; SL-1.

Calculate the section.

Open and close the header (8) to set default parameters and calculate the section. Note that recycle stream 8 experiences 30 iterations and then stops the calculation with a fatal error. To check this error, go to the Model Parameters, Convergence tab, and change the RCYI Recycle stream iteration limit from 30 to 100.

Recalculate the section.

SCREEN SIZE ANALYSIS STREAM NO. 1 STREAM NO. 6 STREAM NO. 7 1 6 7 P80= 6405 P80= 612 P80= 612 ---------------- -------------------- -------------------- -------------------- SCREENS MICRON MT/HR % RET % PAS MT/HR % RET % PAS MT/HR % RET % PAS ---------------- -------------------- -------------------- -------------------- .742 IN 18847 5.100 1.0000 99.00 0.00 0.000 100.00 0.00 0.000 100.00 .525 IN 13335 25.500 5.0000 94.00 0.18 0.011 99.99 0.18 0.011 99.99 .371 IN 9423 30.605 6.0009 88.00 1.26 0.073 99.92 1.26 0.073 99.92 3 TY 6730 35.695 6.9991 81.00 3.16 0.183 99.73 3.16 0.183 99.73 4 TY 4760 35.700 7.0000 74.00 6.11 0.354 99.38 6.11 0.354 99.38 6 TY 3360 35.700 7.0000 67.00 12.41 0.719 98.66 12.41 0.719 98.66 8 TY 2380 35.700 7.0000 60.00 24.44 1.415 97.25 24.44 1.415 97.25 10 TY 1680 30.600 6.0000 54.00 40.39 2.339 94.91 40.39 2.339 94.91 14 TY 1190 35.700 7.0000 47.00 61.73 3.575 91.33 61.73 3.575 91.33 20 TY 841 30.600 6.0000 41.00 86.69 5.021 86.31 86.69 5.021 86.31 28 TY 595 30.600 6.0000 35.00 118.39 6.857 79.45 118.39 6.857 79.45 35 TY 420 35.700 7.0000 28.00 163.55 9.472 69.98 163.55 9.472 69.98 48 TY 297 30.600 6.0000 22.00 197.16 11.419 58.56 197.16 11.419 58.56 65 TY 210 40.800 8.0000 14.00 205.15 11.881 46.68 205.15 11.881 46.68 100 TY 149 30.600 6.0000 8.00 163.15 9.449 37.23 163.15 9.449 37.23 150 TY 105 31.209 6.1193 1.88 141.74 8.209 29.02 141.74 8.209 29.02 200 TY 74 9.591 1.8807 0.00 109.15 6.322 22.70 109.15 6.322 22.70 270 TY 53 0.000 0.0000 0.00 82.51 4.779 17.92 82.51 4.779 17.92 400 TY 37 0.000 0.0000 0.00 72.63 4.207 13.72 72.63 4.207 13.72 600 TY 26 0.000 0.0000 0.00 56.81 3.290 10.43 56.81 3.290 10.43 800 TY 19 0.000 0.0000 0.00 40.16 2.326 8.10 40.16 2.326 8.10 1200 TY 13 0.000 0.0000 0.00 37.77 2.187 5.91 37.77 2.187 5.91 1600 TY 9 0.000 0.0000 0.00 27.47 1.591 4.32 27.47 1.591 4.32 2000 TY 7 0.000 0.0000 0.00 74.61 4.321 0.00 74.61 4.321 0.00

SCREEN SIZE ANALYSIS STREAM NO. 8 STREAM NO. 9 8 9 P80= 812 P80= 170 ---------------- -------------------- -------------------- SCREENS MICRON MT/HR % RET % PAS MT/HR % RET % PAS ---------------- -------------------- -------------------- .525 IN 13335 0.18 0.015 99.99 0.000 0.000 100.00 .371 IN 9423 1.26 0.101 99.88 0.000 0.000 100.00 3 TY 6730 3.16 0.254 99.63 0.000 0.000 100.00 4 TY 4760 6.11 0.492 99.14 0.000 0.000 100.00 6 TY 3360 12.41 0.999 98.14 0.000 0.000 100.00 8 TY 2380 24.44 1.968 96.17 0.000 0.000 100.00 10 TY 1680 40.39 3.252 92.92 0.000 0.000 100.00 14 TY 1190 61.73 4.970 87.95 0.000 0.000 100.00 20 TY 841 86.69 6.980 80.97 0.000 0.000 100.00 28 TY 595 118.38 9.531 71.44 0.010 0.002 100.00 35 TY 420 162.94 13.119 58.32 0.609 0.126 99.87 48 TY 297 187.50 15.096 43.22 9.657 1.993 97.88 65 TY 210 159.94 12.877 30.35 45.207 9.329 88.55 100 TY 149 95.86 7.718 22.63 67.293 13.886 74.66 150 TY 105 69.23 5.574 17.05 72.508 14.962 59.70 200 TY 74 48.76 3.926 13.13 60.387 12.461 47.24 270 TY 53 35.37 2.848 10.28 47.146 9.729 37.51 400 TY 37 30.47 2.453 7.83 42.165 8.701 28.81 600 TY 26 23.54 1.896 5.93 33.270 6.865 21.95 800 TY 19 16.53 1.331 4.60 23.631 4.876 17.07 1200 TY 13 15.48 1.246 3.35 22.290 4.600 12.47 1600 TY 9 11.22 0.904 2.45 16.248 3.353 9.12 2000 TY 7 30.43 2.450 0.00 44.179 9.117 0.00