speed of sag mill pdf


grinding mills in the world The contract comprises the design and manufacture of a Ø40’x29’ SAG mill The mill will be driven by a Gearless Motor Drive (GMD) which, at 280MW, is equal to the largest grinding mill power ever used in the mining industry The SAG mill design is based on Outotec’s proprietary grinding

Difference Between Sag Mill vs Ball Mill - mech4study

Oct 12, 2017· SAG mill make use of steel balls included with some large and hard rocks for grinding These mills utilize the balls in making the large fragments of materials broken into piec The ball charge of a SAG mill is about 9% to 20%This process takes place inside the large rotating drum of SAG mill which is filled with balls partially

Low SAG Mill Critical Speed - Grinding & Classification ,

A well implemented SAG control philosophy should be able to vary the mill speed, in response to variations in feed characteristics If the feed ore becomes softer, then the mill control system should respond to reduce the mill speed You may not need to keep adding grinding media either, if the issue persists too long


SINGLE STAGE SAG/AG MILLING DESIGN ABSTRACT Single stage semi-autogenous / autogenous (S/AG) milling has become a common design for a variety of ore , 5 Low ball charge, high speed SAG mill (4% ball charge, 90% Nc) A cross between AG and SAG for average competency, abrasive or Typically operated in RSA on Witwatersrand Gold Ore

Gearless AG/SAG mills -

Gearless AG/SAG mills With the proven use of gearless drive technology, the limitation of AG/SAG mill size due to gearing constraints has been eliminated is the world's leading supplier of gearless AG/SAG mills

Modelling SAG milling power and specific energy ,

Modelling SAG milling power and specific energy consumption including the feed percentage of intermediate size particles M Silva, A Casali⇑ Mining Engineering Department, Universidad de Chile, Beauchef 850, Santiago 8370448, Chile

The influence of mill speed and pulp density on the ,

THE INFLUENCE OF MILL SPEED AND PULP DENSITY ON THE GRINDING EFFICIENCY 89 Pilot plant description The milling pilot plant consists of two containers mounted on top of each other (see Figures 1 and 2) The bottom container holds the mill, the drive train, rollers and the high-tension cabinet The feed boxes (fine and coarse feed) are built into the

Ball mill - Wikipedia

The ball mill is a key piece of equipment for grinding crushed materials, and it is widely used in production lines for powders such as cement, silicates, refractory material, fertilizer, glass ceramics, etc as well as for ore dressing of both ferrous and non-ferrous metals The ball mill can grind various ores and other materials either wet or dry

Ball Milling - University of Massachusetts Boston

A ball mill is a type of grinder used to grind materials into extremely fine powder 7 Major parameters for ball milling Temperature , Rotation speed 8 Types of Ball Mills

Autogenous and Semiautogenous mills -

Simplifying wet grinding with AG/SAG mills AG/SAG mills are often the optimum solution for wet grinding (achieved in a slurry 50 to 80 percent solids) AG/SAG mills can accomplish the same size reduction work as two or stages of crushing and screening, a rod mill, and some or all of the work done by a ball mill

SAGMILLINGCOM : Mill Critical Speed Determination

Mill Critical Speed Determination 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

A Method of C alculating Autogenous/ Semi-Autogenous ,

SAG mills mimic the same shortcoming It follows that in order to obtain the specifi c energy (SE) to achieve a certain transfer size, based on the 80 per cent passing value, an ineffi ciency factor must be applied to the SE of single stage ball mills, rod mills or AG/SAG mills when calculating power according to the Bond Third Theory method

What is critical speed of a SAG mill - answers

The critical speed of a SAG mill is the speed in RPM's at which centrifugal force causes the material being ground to be held against the inside of the shell This speed is only dependent on the .

Evolution of SAG Mill Process Control at the Xstrata ,

revealed a thermal limitation in the 3000hp LCI variable speed drive system at low mill speeds This event resulted in variable speed operation being suspended, and the mill being operated at a fixed speed (76% of critical) until a thorough analysis of the event could be completed DEVELOPMENT OF A SAG MILL CONTROLLER

A Mechatronic Solution Design and Experience with Large ,

tems for SAG-Mills has become more and more common in the recent years Very high power ratings with excellent dynamic performance and high efficiency over a wide speed range allow advanced optimi-zation of the process The design of such large mill drive systems requires modern simulation tools to verify the system be-havior


nous (SAG) mills were operated at constant speed, however, it has been proved that operation with variable speed presents significant advantages in terms of productivity and efficiency [5]–[7] Most of these mills are driven by adjustable-speed drive synchronous machines, connected to ,


Figures 8 and 9 on the right show results from a gold plant’s SAG mill achieved with MillStar’s Segregated Ore Feed Controller combined with the Power Optimiser: • The standard deviation of the mill feed control is greatly reduced • The cyclone feed is more stable, allowing for consistent size separation and feed to downstream process


Currently because of hard ore conditions the SAG mill speed is run at in fixed speed mode only In the future, if soft or fine ore conditions are restored, we will commission rules to control the SAG mill speed Each decision cycle the expert system will calculate a change in the SAG mill speed set point

Paper # 25 - Copper Mountain Overview on the Grinding ,

Mountain, the inching mode in the ABB drives are currently set to turn the SAG mill at about 10 % of rated speed and the ball mills at about 3% of rated speed (mill speed 040 rpm) Furthermore tests during the hot commissioning have shown that the drives can even operate in inching mode at as little as 1% rated speed (mill speed 010 rpm)

2 0 0 6 - Manta Controls

The Telfer Train 1 SAG Mill Operational data was collected for a six week prior to the installation of the Manta Cube Four sets of SAG mill operational data are graphed as histograms in Figure 10 These are, 1 The SAG mill speed (rpm) 2 The SAG mill power (MW) 3 The SAG mill feed rate (tph) 4 The SAG mill weight (tonnes) Figure 10

critical speed of sag mill pdf - magazenenl

sag mill critical speed dctm critical speed of sag mill pdf Influence of pebble mill operating conditions on ,critical speed of sag mill pdf,, Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore,analysis shows that there will be an increase in fines at% of critical speed Get Info

Model Predictive Control for SAG Milling in Minerals ,

Model Predictive Control for SAG Milling in Minerals Processing | 5 Model Predictive Control on a SAG Mill and Ball Mills The solution for the SAG Mill is an adaptive controller which controls mill load using direct mill weight measurement or indirectly from bearing oil pressure


TECHNICAL NOTES 8 GRINDING R P King 8-2 &ROOLVLRQ 5ROOLQJ ZLWK QLSSLQJ , The effect of varying mill speed on the power drawn by the mill is shown graphically in Figure 84 , LG A mill power equation for SAG mills Minerals and Metallurgical Processing Feb 1990 pp57-62


These equations are used by SMCC Pty Ltd to estimate the specific energy of AG/SAG mills under all normal operating conditions, eg ball load, mill speed, feed size and ore hardness and for all .

Mill (grinding) - Wikipedia

SAG is an acronym for Semi-Autogenous Grinding SAG mills are autogenous mills but use grinding balls like a ball mill A SAG mill is usually a primary or first stage grinder SAG mills use a ball charge of 8 to 21% The largest SAG mill is 42' (128m) in diameter, powered by a 28 MW (38,000 HP) motor

Ball Mill Critical Speed & Working Principle - YouTube

Jun 19, 2015· If 75 percent of critical speed is considered desirable for efficient grinding in a 24 meter (8 foot) diameter mill, then the same will be true for a 50 meter (15½ foot) diameter mill

Advanced Simulation for Semi-Autogenous Mill Systems: A ,

Advanced Simulation for Semi-Autogenous Mill S ystems: A Simplified Models Approach 147 description it is necessary to consider the relationship between the feed stream and mill charge level This relationship is known as the transport rate and is probably the least developed aspect in models proposed so far (Apelt et al, 2002 a,b)

Choosing a SAG Mill to Achieve Design Performance

Choosing a SAG Mill To Achieve Design Performance John Starkey1, Principal Consulting Engineer Sami Hindstrom2, Manager, Grinding Travis Orser2, Project Manager, Grinding 1 Starkey & Associates Grinding Design and Process Engineering 336 – 268 Lakeshore Rd E Oakville, Ontario L6J 7S4

Ball Mill Critical Speed - Mineral Processing & Metallurgy

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 vari Use our online formula The mill speed is typically defined as the percent of the Theoretical .

Comminution ‘18 - min-eng

1400 A model of SAG mill power and its application to real-time mill performance analysis MM Hilden and MS Powell (JKMRC, Australia) 1420 Prediction of slurry grinding due to media and coarse rock interactions in a 3D pilot SAG mill using a coupled DEM-SPH model

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