# sag mill conference sellsag mill critical speed

### Benchmarking: Yanacocha Single-stage SAG Mill -

† The %critical speed values given in the text do not appear to account for the liner. The RPM values are assumed to be correct and the %critical speed values have been back-calculated. Simplified Morrell SAG mill model was run, default k=1.26 (motor input basis) used.

Get PriceEmail contact### Benchmarking: Fimiston Ball Mills - SAGMILLING.COM

† The appendix of the paper lists the mill speed as 12.5 RPM. The mill is fixed speed, so the %critical speed is only a function of mill effective diameter (as liners wear). Doing the math (neglecting the balls) gives a 68.4% critical speed. The ball mill belly length can be achieved with a 18 degree head angle and 1.9 m trunnion diameter.

Get PriceEmail contact### Operation Analysis of a SAG Mill under Different ...

In the simulation, to study the effect of mill speed ratio and mill fill level ratio on the fracture effect of the SAG mill, as shown in Figure 6a,b, when the mill speed ratio is between 65% and 90% of the critical speed, the total mass curve of the rock below 25 mm in the mill presents normal distribution. When the speed is 80% of the critical speed, the fracture effect is the best. The total ...

Get PriceEmail contact### 2020 Ascot Resources Ltd.

15/10/2020 The order comprises a 22-foot diameter by 8-foot effective grinding length(egl) SAG mill and 14.5-foot diameter by 19.5-foot effective grinding length ball mill. Both mills will be driven by 2000 KW, low speed synchronous motors at 78% critical speed. The mills will be supported on 90-inch diameter hydrodynamic trunnion bearings which will be interchangeable. The mill lube systems will be ...

Get PriceEmail contact### (PDF) Maximising SAG mill throughput at Porgera gold

Summary of Mill Survey Results 80 survey 1, SAG 2 70 Survey 1 2 2 3 60 Blast # 340-319 320-314 320-314 310-316 SAG 1 Muck Load, vol % 26.3 22.8 - 26.9 50 Ball Load, vol % 11.0 13.8 13.8 13.2 40 Ball Size, mm 150 125 125 125 30 Power, KW 4550 4650 3970 4310 20 Bearing Pressure, 3900 3740 3720 3927 10 kpa 0 Mill Speed, rpm 11.42 11.42 10.79 11.50 10 100 1,000 10,000 100,000 1,000,000 SAG

Get PriceEmail contact### Performance enhancement tools for grinding mills

In recognition of ore variability, many current SAG mills are installed with variable speed drives, capable of operating the mill through a wide and continuous range of speed values. Mill speed and liner profile determine grinding media trajectories, as shown in Figure 1. By increasing mill speed or the steepness of liner attack angle,

Get PriceEmail contact### STEPPING FORWARD: USING VARIABLE SPEED DRIVES FOR ...

The breakage rate function shape of the SAG mill is largely governed by the mill load particle size distribution and mill speed. The feed in the mill contains fractions of ore that serves as the grinding media. Larger ore fractions break the smaller particles but also breakdown themselves and exit the mill as a product. In due course, the ore competency can change as fresher, harder ore is ...

Get PriceEmail contact### Preprint 13-050

SAG mill conference, provided details of the then largest gear drive in operation on a SAG mill (34ft x 18ft) at Escondida 13.4MW, which began operation in 1995. The reason for not having larger gear drives was due to the limitation of gear manufacturers not having access to larger single piece special alloy castings. To the benefit of

Get PriceEmail contact### The Effect of Aspect Ratio on the Grinding Efficiency of ...

80 = 80 per cent passing size of AG/SAG mill circuit DW i = drop-weight index J = volume of balls (per cent) φ = mill speed (per cent of critical) f(A r) = function of mill aspect ratio a,b,c,d,e,f,g = constants K = function whose value is dependent upon whether a pebble crusher is in circuit WMKx x()() i =−fx fx 21 21 (3) where: W ...

Get PriceEmail contact### Hill grinding circuit liner design has been the subject of ...

wasincreased from 8.6rpm (71% critical speed) to 9.6rpm (79% critical speed). A quicker ramp up of the mill was sought. • High noise levels arose once the mill direction was reversed (usually a month to six weeks after the reline). Hence there was a further requirement to operate the mill at slower than optimum speed for a second time.

Get PriceEmail contact### Optimal Speed Control for a Semi-Autogenous Mill Based

Speed rate refers to the ratio of the speed of the mill to the critical speed, where the critical speed is n c = 30 / R. In practice, the speed rate of the SAG mill is generally 65% to 80%. Therefore, in the experiment, the speed was set to vary in 50% and 90% of the critical speed (1.28–1.64 rad/s) for the cross-over test as shown in

Get PriceEmail contact### C O N S U L T I N G L T D TECHNICAL MEMORANDUM

The power consumed by a ball mill is described in equation 9.16 in the JKMRC text. The power is a function of mill diameter, volume fraction filled with balls, fraction of critical speed, ball size, and the tonnage of balls in the mill. These parameters are adjusted to provide a mill geometry and charge

Get PriceEmail contact### (PDF) Maximising SAG mill throughput at Porgera gold

Summary of Mill Survey Results 80 survey 1, SAG 2 70 Survey 1 2 2 3 60 Blast # 340-319 320-314 320-314 310-316 SAG 1 Muck Load, vol % 26.3 22.8 - 26.9 50 Ball Load, vol % 11.0 13.8 13.8 13.2 40 Ball Size, mm 150 125 125 125 30 Power, KW 4550 4650 3970 4310 20 Bearing Pressure, 3900 3740 3720 3927 10 kpa 0 Mill Speed, rpm 11.42 11.42 10.79 11.50 10 100 1,000 10,000 100,000 1,000,000 SAG

Get PriceEmail contact### (PDF) Real-Time Simulation and Control of a SAG Mill

As part of the development of a general simulation model for semiautogenous (SAG) mills it was found necessary to have mill power equations for the large D/L (pancake) type of SAG mill popular in ...

Get PriceEmail contact### Curved Pulp Lifters – Can They Save Energy? - CEEC ...

The SAG mill was originally equipped with radial pulp lifters. The mill runs at fixed speed of 10.9 rev/min, which is approximately 80 per cent of critical speed (per cent CS). Due to the high speed of the mill the original radial design pulp lifters presented a high volume of recirculating load inside the chamber and consequently heavy wear on the outer circle (bottom pan).

Get PriceEmail contact### Preprint 13-050

SAG mill conference, provided details of the then largest gear drive in operation on a SAG mill (34ft x 18ft) at Escondida 13.4MW, which began operation in 1995. The reason for not having larger gear drives was due to the limitation of gear manufacturers not having access to larger single piece special alloy castings. To the benefit of

Get PriceEmail contact### COMMINUTION CIRCUITS A SUMMARY OF ENERGY EFFICIENCY ...

2 SAG CONFERENCE 2019 VANCOUVER SEPTEMBER 22–26, 2019 Figure 2 – SAG and Ball Mill Grinding Flowsheet The SAG mill grinding circuit includes a 34 ft x 15.25 ft SAG mill operated with a 10.5 MW variable speed drivetrain. SAG mill product is screened at ~12 mm; oversize is conveyed to the pebble crushing circuit operating with one HP800 cone crusher. Screen undersize is pumped to the ...

Get PriceEmail contact### SAGMILLING.COM .:. Articles

SAG Mill power draw models are used in mill design and grinding circuit modelling to predict how muc h pow er wi... [↓ read more ↓] Alex Doll: modelling: A simple estimation method of materials handling specific energy consumption in HPGR circuits [] Multi-stage crushing plants, including high pressure grinding roll (HPGR) circuits, require more mat erial s han... [↓ read more ↓] Alex ...

Get PriceEmail contact### Hill grinding circuit liner design has been the subject of ...

wasincreased from 8.6rpm (71% critical speed) to 9.6rpm (79% critical speed). A quicker ramp up of the mill was sought. • High noise levels arose once the mill direction was reversed (usually a month to six weeks after the reline). Hence there was a further requirement to operate the mill at slower than optimum speed for a second time.

Get PriceEmail contact### (PDF) Simulation of overflow ball mill discharge and ...

together at 75% mill critical speed (1 3.2 rp m) until the flow of ball charge within the mill is at steady st ate. The SPH fluid slurry is the n added. Fluid is filled auto matically within the ...

Get PriceEmail contact### C O N S U L T I N G L T D TECHNICAL MEMORANDUM

The power consumed by a ball mill is described in equation 9.16 in the JKMRC text. The power is a function of mill diameter, volume fraction filled with balls, fraction of critical speed, ball size, and the tonnage of balls in the mill. These parameters are adjusted to provide a mill geometry and charge

Get PriceEmail contact### Curved Pulp Lifters – Can They Save Energy? - CEEC ...

The SAG mill was originally equipped with radial pulp lifters. The mill runs at fixed speed of 10.9 rev/min, which is approximately 80 per cent of critical speed (per cent CS). Due to the high speed of the mill the original radial design pulp lifters presented a high volume of recirculating load inside the chamber and consequently heavy wear on the outer circle (bottom pan).

Get PriceEmail contact### Paper # 25 - Copper Mountain Overview on the Grinding ...

(76 percent of critical speed average) Ore specific gravity (sg) 2.77 ... SAG mill rated motor speed 204 rpm, max. motor speed 214 rpm Ball mill rated motor speed 195 rpm, max. motor speed 209 rpm Starting torque: 150% for 15 s Main voltage level where the drive system is connected: 25 kV Excitation power is provided by a 4.16 kV bus As the power requirements for the SAG and ball mill drives ...

Get PriceEmail contact### Pilot and laboratory test procedures for the design of ...

The SAG mill has an inside diameter of 1.7 m and an effective length of 0.5 m. The mill operates at 75 per cent of critical speed. It is equipped with six peripheral ports (each 75 mm by 175 mm). Each peripheral port can accommodate a range of grate discharge and pebble port geometry. To control the feed rate to the mill, Mintek piloting

Get PriceEmail contact### (PDF) SINGLE STAGE SAG/AG MILLING DESIGN SINGLE

These mills were often high fixed speed, low ball charge, SAG mills.To compensate for the identified potential problems, a number of design changes were made compared to those typically employed in South Africa.The selected mill had a variable speed drive to cater for changes in feed competency and rock content. The SAG mill was also designed with a high maximum ball charge (18%) so that ...

Get PriceEmail contact### Preprint 13-050

SAG mill conference, provided details of the then largest gear drive in operation on a SAG mill (34ft x 18ft) at Escondida 13.4MW, which began operation in 1995. The reason for not having larger gear drives was due to the limitation of gear manufacturers not having access to larger single piece special alloy castings. To the benefit of

Get PriceEmail contact### COMMINUTION CIRCUITS A SUMMARY OF ENERGY EFFICIENCY ...

2 SAG CONFERENCE 2019 VANCOUVER SEPTEMBER 22–26, 2019 Figure 2 – SAG and Ball Mill Grinding Flowsheet The SAG mill grinding circuit includes a 34 ft x 15.25 ft SAG mill operated with a 10.5 MW variable speed drivetrain. SAG mill product is screened at ~12 mm; oversize is conveyed to the pebble crushing circuit operating with one HP800 cone crusher. Screen undersize is pumped to the ...

Get PriceEmail contact### SAGMILLING.COM .:. Articles

SAG Mill power draw models are used in mill design and grinding circuit modelling to predict how muc h pow er wi... [↓ read more ↓] Alex Doll: modelling: A simple estimation method of materials handling specific energy consumption in HPGR circuits [] Multi-stage crushing plants, including high pressure grinding roll (HPGR) circuits, require more mat erial s han... [↓ read more ↓] Alex ...

Get PriceEmail contact### Ascot Places Order for the SAG and Ball Mills

15/10/2020 The mill lube systems will be identical for both mills (see Figure 1).Derek White, President and CEO of Ascot, commented, “The Ascot team has worked diligently over the summer to complete all of the engineering work to put us in a position to place the order for the SAG Ball mills. This equipment is critical to our construction timeframe and having the support and expertise of Farnell ...

Get PriceEmail contact### Ascot Places Order for the SAG and Ball Mills, by @nasdaq

VANCOUVER, British Columbia, Oct. 15, 2020 (GLOBE NEWSWIRE) -- Ascot Resources Ltd. (TSX: AOT; OTCQX: AOTVF) (“Ascot” or the “Company”) is pleased to announce it has signed an agreement for the delivery of the Semi-Autogenous Grinding (“SAG”) and ball mills, which is critical path, long lead time equipment required in the refurbishment of the concentrator facility for re-starting ...

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