# sag mill critical speed

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### Modelling SAG milling power and specific energy

Modelling SAG milling power and specific energy consumption including the feed percentage of intermediate size particles In general these equations are used to predict power consumption as a function of mill size level and density of the internal charge and of critical speed Almost none of these equations with the notable exception of

Get Price### Ball Mill Critical Speed

2015 6 19 A Ball Mill Critical Speed actually ball rod AG or SAG is the speed at which the centrifugal forces equal gravitational forces at the mill shell s inside surface and no balls will fall from its position onto the shell The imagery below helps explain what goes on inside a mill as speed varies Use our online formula The mill speed is typically defined as the percent of the Theoretical

Get Price### Gearless mill drives

2021 2 16 28 MW GMD for a 40 SAG mill 28 MW GMD for 42 SAG mill Whether it is size or an installation at the highest altitude 4600 m.a.s.l ABB s GMDs are well positioned to contribute to the building of larger and ever more powerful mills Leading the gearless mill drive evolution The ABB gearless mill drive GMD is the most powerful

Get Price### Boost the performance of your SAG Mill

Enhanced mill performance SAGwise total process control uses specially designed acoustic sensors and proprietary process control software to monitor and respond to critical impacts inside your SAG Mill Conditions inside your mill are automatically adjusted to minimise liner damage stabilise and then optimise the operation of a SAG Mill.

Get Price### search results critical speed of mill formulae

Ball Mill Critical SpeedMineral Processing Metallurgy Jun 19 2015 A Ball Mill Critical Speed actually ball rod AG or SAG is the speed at which the centrifugal forces equal gravitational forces at the mill shell s inside surface and no balls will fall from its position onto the shell.

Get Price### Major Mines Projects

A speed range of 60 to 80 critical speed is available though the mill can be slowed down further for softer ore types SAG mill steel ball grinding media is typically 100mm to 125mm diameter The SAG mill product discharges into a vibrating single deck heavy duty pebble dewatering screen fitted with a nominal 15mm aperture polyurethane

Get Price### SAG Mill

Type SAG Mill Make Model no Condition New Year 2013 Power 2463 kW 3300 hp Frequency 60 Hz Voltage 4000V Specifications Effective Grinding 21 x9 Mill Speed Design 75 of Critical Motor Speed 1185 RPM Gear box output 240 RPM 12 Ball load by Vol Full Package Includes Inching drive

Get Price### Updates on geared vs gearless drive solutions for grinding

2021 9 27 Among the many reasons that geared drives on large SAG mills are not favoured is due to not having an efficient variable speed drive option 60 to 80 critical speed which is required for process reasons As technological advances have occurred quite rapidly in recent years this paper uses the latest data in applying these comparisons and

Get Price### Calculating Mill Drive RPMs Is Your Mill Up to Speed

2021 10 27 By Robert A Sladky Vice President Tube Mill Engineering Many W style mills that have the ability to shim up the bottom driven shafts in each section to maintain metal line after tooling is reworked and are many times also equipped with a individual motor drive in each of the three sections as illustrated below.

Get Price### calculate the critical speed of a rod mill

calculate the critical speed of a rod mill calculate the critical speed of a rod mill Ball Mill Critical Speed Mineral Processing 2020 5 4 A Ball Mill Critical Speed actually ball rod AG or SAG is the speed at which the centrifugal forces equal gravitational forces at the mill shells inside surface and no balls will fall from its position onto the shell.

Get Price### derive the equation of critical speed of ball mill

Ball mill critical speed 911 metallurgist peru ball mill critical speed derivation a ball mill critical speed actually ball rod ag or sag is the speed at which e formula derivation ends up as follow critical speed is nc1 page the comminution circuit design for the the circuit consists of

Get Price### TECHNICAL How to Spec a Mill Gear

2014 7 17 a theoretical critical speed of rotation CS The critical speed of rotation is the speed in rpm at which an infinite ly small particle will cling to the inside of the liners of the mill for a complete revolution 1 CS = 43.305 √Mill Diameter where CS is the theoretical critical speed of rotation and is the mill speed rpm Mill

Get Price### ONLINE SAG MILL PULSE MEASUREMENT AND

2006 6 24 A 35 decrease in the SAG mill power draw from 3 908 HP to 2 526 HP 2 915 kW to 1 884 kW was recorded This equates to a 47 decrease in SAG unit energy consumption from 8.98 kWh/ton to 4.74 kWh/ton A 11 decrease in SAG mill speed was observed indicating optimized ball strikes.

Get Price### SAG Mill

2014 3 19 The SAG mill and all other grinding equipment is remotely monitored and controlled via computer from a central control room The control room operator watches four video terminals and a CCTV monitor to keep track of critical process variables impacting mill throughput.

Get Price### Finding the right sound in your SAG mill

Audio sensors close to the SAG mill listen for undesirable high energy critical impacts Intelligent software analyses the patterns and adjust feed speed and pulp density for optimal efficiency to decrease power usage reduce critical impacts and preserve liner life Benefits Increase liner life Decrease critical

Get Price### PDF Optimal Speed Control for a Semi Autogenous Mill

the size and number of particles in the SAG mill was mainly investigated based on discrete element method For optimal speed control an improved sliding mode control of the exponential

Get Price### SAG mill wear optimization using DEM simulation

2018 3 13 The mill processes rocks from 200 mm to 300 mm using 350 mm steel balls as the grinding medium The equipment works under these conditions speed 10 rpm 80 percent of critical speed volumetric filling 14.5 percent ratio of balls to rocks 4 1 in mass.

Get Price### GROSS POWER CALCULATOR

2020 3 24 AG/SAG mills in the data this covers mill dimensions speed of rotation whether the mill has cone ends and type of discharge mechanism Dimensions can be input in either metric or imperial units by the use of the drop fraction of critical speed 0.6 0.82 0.5 0.9 cone angle deg 0 26 0 15 CONTENTS DATA ore sg 2.6 4.5 2.6 4.5

Get Price### Mill Critical Speed Calculation

2015 10 15 The mill was rotated at 63 of the critical speed The position of the balls at the end of five revolutions is shown in Figure 2 It is seen that using a low coefficient of friction at the walls balls tend to flow down the surface of the charge and a toe begins to form As the friction at the wall increases cataracting motion is observed.

Get Price### how to calculation critical speed of sag mill

critical speed of sag mill sag mill speed as a fraction of critical speed A Ball Mill Critical Speed actually ball rod AG or SAG is the speed at which the centrifugal forces equal gravitational forces at the mill shell s inside surface and no balls will fall from its position onto the

Get Price### specs of sag mill balls

SAG mills 20 v v ball charge 30 v v filling and 78 critical speed requirements Example SG 4 0 38 39 Ø 19 39 EGL SAG Requires 21 5 MW at mill shell FL SAG AG Mills 30 years experience with Semi Autogenous and Autogenous Grinding Mills in size from 18 39 through 40 39 in diameter with powers as high as 30 000 hp Semi autogenous grinding uses

Get Price### SAG Mill Optimization using Model Predictive Control

Control of SemiAutogenous Grinding SAG mill weight is an example of an important process that exhibits many of these aspects Maintaining the SAG mill weight at the optimum value is critical for achieving maximum grind rate efficiency and mill production Powell M.S van der Westhuizen A.P Mainza A.N 2009 .

Get Price### White paper September 2015 SmartMill Exceed your

2021 2 15 mills SAG mills of over 40 foot diameter have been constructed Like the ball mill the AG/SAG mill will have a critical rotation speed above which grinding ceases Mill motor types There are three common motor types that drive the grinding mills described above Gearless motors These variable speed motors range up to 30 MW and have the

Get Price### OPTIMISATION OF THE CLASSICAL SEMI AUTOGENOUS

2021 1 6 of the SAG mill which were mill filling ball filling ball size and mill speed The AR technique graphically presented the results which indicated the best operating conditions to minimise pebble formation The effects of mill filling on a SAG mill indicate that a higher filling produces lower pebbles.

Get Price### specs of sag mill balls

SAG mills 20 v v ball charge 30 v v filling and 78 critical speed requirements Example SG 4 0 38 39 Ø 19 39 EGL SAG Requires 21 5 MW at mill shell FL SAG AG Mills 30 years experience with Semi Autogenous and Autogenous Grinding Mills in size from 18 39 through 40 39 in diameter with powers as high as 30 000 hp Semi autogenous grinding uses

Get Price### Benchmarking Ball Mill Power Draw Models

2020 3 22 Mill speed critical Total load v/v Pulp solids w/w Morrell SAG Model kW at input shell Model no density correction kW at input shell Model density correction kW at input shell Survey 1 3 864 66.7 68.4 † 38.7 72.0 3 798 3 798 3 619 3 370 3 894 3 626

Get Price### Benchmarking Yanacocha Single stage SAG Mill

2020 3 22 † 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 Price### Modelling SAG milling power and specific energy

Modelling SAG milling power and specific energy consumption including the feed percentage of intermediate size particles In general these equations are used to predict power consumption as a function of mill size level and density of the internal charge and of critical speed Almost none of these equations with the notable exception of

Get Price### Optimisation of a SAG mill though trajectory and power

2021 8 29 Thus both total percent mill filling and mill trajectory are critical parameters however neither is reported or available to metallurgy or processing teams in real time or a regular basis In this study the performance of a fixed speed SAG mill was assessed and optimised by employing mill trajectory models and using the JKMRC power model to

Get Price### Benchmarking Bond

2020 5 20 Raising the SAG speed to 78 of critical speed 10.4 RPM has little effect due to the drop off in power observed in a Loveday model using Barratt s published Power Numbers above 76 of critical speed The model predicts a negative phantom cyclone effect This is an odd result but does match one observation on a hard ore Boddington circuit

Get Price### FREDA REBECCA SAGMILLING CIRCUIT OPTIMIZATION

2021 3 26 2.1 AUTOGENOUS AG AND SEMI AUTOGENOUS SAG MILL OPERATION Semi autogenous grinding is one of the most used processes for comminution The process involves feeding rock particles and water into the grinding mill containing a fraction of steel balls usually below 10 and running at a fraction of its critical speed.

Get Price### The engineering and process effects of choosing a motor

2021 10 5 RPM is the mill rotational speed revolutions per minute ⌽ C is the mill rotational speed fraction of critical speed eg 0.72 for 72 D is the mill nominal diameter inside the shell m d is the mill liner nominal thickness m Figure 4 „Tent diagram for the Cadia SAG mill described in Figure 3

Get Price### SAGMILLING

The Critical Speed for a grinding mill is defined as the rotational speed where centrifugal forces equal gravitational forces at the mill shell s inside surface This is the rotational speed where balls will not fall away from the mill s shell Result #1 This mill would need to spin at RPM to be at 100 critical speed Result #2 This mill s

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