SAG MILLS OPTIMIZATION: IMPLEMENTATION AND EVALUATION IN DOÑA INÉS DE COLLAHUASI MINING L. Magne, J. Tapia, E. Altamirano, C. Muñoz, G. Titichoca, I. Yutronic CMDI de Collahuasi Lmagne Ingeniería
Compañía Minera Doña Inés de Collahuasi Is located 4.400 meters above sea level in the Andean plateau of the Tarapacá Region of the far north of Chile, to 245 km from Iquique.
Semiautogenous Grinding Circuit Line #1 CS - 001 CS - 002 SAG 1 Fe - 003 Fe - 004 BM 3 DI 01 Fe - 005 CV - 05 PP- 03 PP- 04 Fe - 006 Fe - 007 Fe - 008 CV - 09 CV - 07 SU - 01 DI 02 Fe - 1031 Fe - 1032 Fe - 1034 Fe - 1035 Line #2 CS - 003 CS - 004 Fe - 1033 Fe - 1036 Fe - 1037 Fe - 1038 SAG 2 BM 4 CV - 06 PP- 05 PP- 06 CS - 1011 CS - 1012 SAG Power Ball mill Mill ball Power Line D x L, foot HP number D x L, foot HP 1 32 x 15 11.000 1 22 x 36,5 13.000 2 32 x 15 11.000 1 22 x 36,5 13.000 1011 40 x 24 28.000 2 26 x 38 20.000 CV - 1035 CV - 10 CV - 08 SAG 1011 SU - 02 Line #3 BM 1013 PP- 1021 PP- 1022 PP- 1023 PP- 1024 BM 1012 CS -1013 CS - 1014 DI 1051 SU - 1021 CV - 1037 CV - 1038 CV - 1036
Trommel: classification efficiency laundry water Semiautogenous Mill Optimization SAG 1011: Charge baffle in trunnion End discharge: Grates Pulp lifters Cone discharge Liners design
SAG Mills Linings Design d= distancia media entre lifters d = media distance between lifters Area between lifters Área entre lifters h = free lifters media high h: altura media de lifter libre 1.941 cm2 d/h = 2,56 (706/276) Vlift/Vmol ~ (Área entre lifters x filas de lifters)/área transversal del molino d/h: it relates liners distance and media box high between lifters Vlift/Vmill: it relates volume between liners and mill volume Lifting angle: is the attack lifter s angle (one o more) Using MillMED simulations is calculated the effect over: Useful impacts (Ball-Ore, Ore-Ore, Ore-Liners) Useless impacts (Ball-Ball, Ball-Liners)
60 54 56 SAG Mills Linings Design: Relation Between SAG Diameter and Row Lifters Number 48 Cantidad Filas Lifters 42 36 30 27 30 30 30 30 30 30 32 32 36 36 36 36 36 36 36 36 36 30 30 30 24 18 28 28 28 28 32 32 32 32 34 34 36 36 36 36 36 36 36 36 36 38 38 40 Diámetro Molino (pies) 4,50 4,00 4,0 4,2 3,50 3,00 3,3 2,9 3,4 3,3 3,3 3,1 2,50 2,00 2,00 1,50 1,6 1,00 0,96 1,07 0,94 0,94 0,94 1,00 0,79 0,75 0,50 0,00 28 28 28 32 34 34 36 38 40 Diámetro Molino (pies) Cant. Filas Lifters/Diám. Molino (pies) Distancia Entre Centro de Lifters (pies)
SAG Mills Linings Design: SAG 1-2 d= distancia media entre lifters Original design d/h 2,44 2,19 2,32 V between lifters 6,9% 8,3% 7,7% h/mill diameter 2,5% 2,9% 2,8% Propoused Average Differences: design industry Differences: Smaller superior lifting angle (42 vs 52 ) Fall of the load near to foot of load Bigger lifting angle in intermediate area (26 ) Better energy distribution and bigger load in flight Lifting capacity independent of the waste Bigger lifters height: 43 mm Bigger load volume in flight Bigger duration of the lining (15% with 150 mm of retirement thickness)
SAG Mills Linings Design: SAG 1011 Original design Propoused design Average industry d/h 4,37 3,19 2,32 V between lifters 5,1% 6,9% 7,7% h/mill diameter 1,6% 2,4% 2,8% Differences: Variable angle since 35 Fall of the load near to foot of load Better energy distribution and bigger load in flight Lifting capacity independent of the waste Bigger lifters height: 71 mm Bigger load volume in flight Bigger duration of the lining (18% with 150 mm of retirement thickness)
Trommel s Classification Efficiency Mill Trommel's Dimension Capacity Slot Size Open SAG Plant Diameter, feet Diameter, feet Long, feet Screen tph Wide, mm Long, mm Area, % C.M.D.I. Collahuasi 32 14,4 13,6 No 1.320 15 30 27,0 Minera Los Pelambres 36 15,9 16,4 No 2.912 17 38 26,0 Minera Escondida 38 20,3 11,2 Si 5.170 25 60 29,0 Minera Antamina 38 15,9 16,4 No 5.472 15 38 23,0 C.M.D.I. Collahuasi 40 16,5 16,9 No 4.480 25 50 22,8 Minera Esperanza 40 15,4 15,4 Si 5.160 13 39 25,0 Comparison criteria: α parameter: 3 m α 2 m h = Volumetric slurry Open area flow 2 [ m ] m h 3
Trommel s Classification Efficiency Mill Trommel's Dimension Pulp Trommel Free Flow by Free SAG Plant Diameter, feet Diameter, feet Long, feet Flow, m 3 /h Area, m 2 Area, m 2 Area, m 3 /m 2 /h C.M.D.I. Collahuasi 32 14,4 13,6 935 57,0 15,4 61 Minera Los Pelambres 36 15,9 16,4 2.063 75,9 19,7 105 Minera Escondida 38 20,3 11,2 3.570 66,2 19,2 186 Minera Antamina 38 15,9 16,4 3.877 76,0 17,5 222 C.M.D.I. Collahuasi 40 16,5 16,9 3.174 81,2 18,5 172 Minera Esperanza 40 15,4 15,4 3.656 69,4 17,3 211 32 feet Collahuasi SAG mills, have the best condition of slurry evacuation in trommel: α = 61 m 3 /h/m 2 Antamina s SAG mill has the worst condition of slurry evacuation in trommel: α = 222 m 3 /h/m 2 Esperanza and Escondida s SAG mills have high values of α, but they have a screen Trommel of 40 feet SAG mill of Collahuasi has an high value of α = 172 m 3 /h/m 2. Open Pulp Free Flow by Free SAG 1011 Area, % Flow, m 3 /h Area, m 2 Area, m 3 /m 2 /h Initial Condition 22,8 3.174 18,5 172 Modification 1 35,0 3.174 28,4 112 Modification 2 31,8 3.174 25,8 123 Modification 3 29,2 3.174 23,7 134 28% more than the free area permit 22% more than flow discharge capacity
Trommel s Classification Efficiency: Laundry Water SAG 1-2 SAG 1011
Pulp Lifters and Cone Discharge of SAG Mills 6,8 (6 ) Recirculación producto del desgaste del pulplifter largo en el extremo de salida de la carga 8 (7,25 ) En blanco, medida el 16 de febrero de 2010 En amarillo, medida original Zona caída de carga
Pulp Lifters and Cone Discharge of SAG Mills Cone discharge design affect: Discharge flow capacity (then, mill capacity) Slurry trajectory Slurry return from the trunnion Use of the trommel area for clasiffication Excessive wear in preferential areas of the trommel 1 6 1 5 1 4 1 3 1 2 1 1 1 0 9 8 7 6 5 4 3 2 1
Pulp Lifters and Cone Discharge of SAG Mills Size of SAG Grate: 64 mm 583 mm 476 mm 182 mm 188 mm Strangulation of 182 mm Strangulation of 188 mm Opposing directors 289 mm 385 mm 328 mm Material: Polyurethane Cone discharge of SAG 1-2 Material: Rubber with ceramics
Pulp Lifters and Cone Discharge of SAG Mills Size of SAG Grate: 64 mm 697 mm 307 mm The short directors is near to medium directors Strangulation of 95 mm 674 mm 350 mm 95 mm 298 mm 503 mm Material: Polyurethane Material: Rubber with ceramics Cone discharge of SAG 1011
Charge Baffle in SAG 1011 Trunnion - Trommel
Charge Baffle in SAG 1011 Trunnion - Trommel It is possible to eliminate one blind line Trunnion liner with positive angle Grates in discharge zone, for maximum evacuation
Plant Results SAG 1-2: The cilinder liners useful life increased in 15% (from 4,6 Mt to 6,3 Mt) Ball load level incresed since 12 to 16%, and until 18%, without risk of damage of linings Bigger operational speed from the begining of useful life of liners By pass of fines decrease (washed pebbles) Mill capacity increased up to 1.800 tph (from 1.400 tph, 28%) SAG 1011: The cilinder liners useful life increased in 34% (from 8,5 Mt to 11,4 Mt) Ball load level incresed since 14 to 16%, without risk of damage of linings Bigger operational speed from the begining of useful life of liners The trommel s mesh useful life incresed from 45 to 75 days Strong decrease of by pass of fines (washed pebbles) Pebbles belt is not a restriction of the process and the accidental detentions (for masive discharge of load) were eliminated Mill capacity increased up to 5.500 tph (from 3.900 tph, 41%)
Plant Results We want to thank to all the suppliers that have participated and contributed their experience and commitment in the carried out developments.