MODEL PREDICTIVE CONTROL OF SAG MILLS AND FLOTATION CIRCUITS *Michael G Forbes and Bill Gough mike forbesandritz) ABSTRACT Precise control of SAG mill loading and flotation cell level is critical to maximize production and recovery in mineral concentrators (such as rotation speed and ore feed rate on SAG mill weight)

SAG mill maintenance and relining is a field where finding and employing expertise pays dividends As the engine of a mining operation a SAG mill can process hundreds of thousands of tonnes of ore each day grinding rock into suitable fractions that can be further processed to

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

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

Evolution of SAG Mill Process Control at the Xstrata Nickel Raglan Operation Erik Bartsch1 Chief Engineer - Mill rotation speed (operator set-point) - Mill power and bearing pressure indication fixed speed (76% of critical) until a thorough analysis of the event could be completed

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

Rod mills operate at lower speed than ball mills since the rods are rolled and not cascaded For an equivalent grind a rod mill uses less steel than a ball mill because of the lower speed and better contact between the media and ore The Critical Speed is used for the determination of ball mill ideal operating speed

SAG Mill Below Critical Speed Read more Discrete Element Method analysis using EDEM Simulation of a sag mill running below critical speed Rock Box Mineral Velocity Read more Discrete Element Method analysis using EDEM Simulation is of mineral conveyed into a rock box or chute and falling onto an inclined conveyor

A grinding mill (F305 mm 305 mm) was used for the Bond ball mill work index test [18–21] This ball mill was ﬁlled with 285 steel balls (total weight of 20 125 kg) at an operation speed of 70 rpm The feed sample was prepared via crushing and sieving giving rise to a size smaller than 3 35 mm

APPLICATION OF THE MINNOVEX SAG POWER INDEX AT FIVE CANADIAN SAG PLANTS crushing equipment in the SAG circuit to prevent build up of critical size material in the mill which is the single speed drive common configuration and a moderate steel load of 9%

Keep your business rolling Mill Lining Solutions Mill linings mill trommels and trunnion linings 2 a monitor to speed up mill liner installations and improve safety for only a fraction of the total grinding cost but an inferior lining can prove to

the mill speed from 36% to 80% of critical speed The general flowsheet of the circuit is shown in Figure 9 Figure 9: Cortez Gold Mines Mill #2 Flowsheet Only the DE – discharge end consisting of grate and pulp lifters were replaced in the SAG mill The ball charge was kept same at 9 08%

MODEL PREDICTIVE CONTROL OF SAG MILLS AND FLOTATION CIRCUITS *Michael G Forbes and Bill Gough mike forbesandritz) ABSTRACT Precise control of SAG mill loading and flotation cell level is critical to maximize production and recovery in mineral concentrators (such as rotation speed and ore feed rate on SAG mill weight)

Investigations were carried out in a laboratory ball mill having the size of DxL = 160x200 mm with a ribbed inside surface of the drum The mill ball loading was 40% by volume the rotation rate was equal to 85% of the critical speed Balls were made from steel: S4146 extra high quality having hardness 62 2 HRC according to Rockwell

The specific power curves for all the cases with ball fractions - 80% are very close together The differences are very small for all sub-critical mill speeds with larger but still modest differences at super-critical speeds Cases with ball fractions as high as 80% behave essentially the same as the autogenous case

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

autogenous (SAG) Mill via an utilized method Miduk SAG Mill circuit is shown in Figure 1 Figure 1: Diagram of Miduk Copper Complex SAG Mill Methods The following methods were utilized in this research work for ball filling calculation To fulfill this aim three approaches were investigated

Figure 3 4 – Influence of fraction of the critical speed on power consumption (Kelly and (2001) at 80% critical speed with 35% mill filling (dashed line) and the analysis done for the PEPT mill system at 75% critical speed (full line) 46 Figure 5

Proposed milling circuit modifications include close circuiting the SAG mill by recycling a portion of the ball mill cyclone underflow increasing the SAG mill speed from 73% to 79% of critical and offloading of lower than feed grade -20mm /+7mm SAG mill ore scats

Ball mills are among the most variable and effective tools when it comes to size reduction of hard brittle or fibrous materials The variety of grinding modes usable volumes and available grinding tool materials make ball mills the perfect match for a vast range of applications

effect of varying the mill speed as a fraction of the critical speed ⌽ C can be observed by plotting the process power and torque draw superimposed on the relevant motor capability curve Such plots for an example mill the SAG mill at Cadia (described by Dunne et al 2001) is shown in Figure 3

model) as a fraction of the mill diameter (D) δc is modelled empirically as function of operating variables as follows: [3] J: Total load volume as a fraction of total mill volume N: Mill Speed as a percentage of the Critical Speed ∆J: governs the strength of the dependence of δc

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 Ball mill is mechanically rotated Live Chat Mill Speed - Critical Speed - pauloabbe

Eduardo Nozawa Caetano de Araujo and Homero Delboni Jr Abstract Tumbling mills are often taken as the object of optimization studies because they are a type of equipment that consume large amounts of energy Among the cur-rent available resources to

Many variables influence the size reduction performance in a mill including the media size shape quality the properties of the incoming ore feed the ratio of feed to media and the speed of the mill Since grinding media performance is critical to mineral processing operations it's important to partner with a quality supplier such as SGI

This rB rate constant for attrition of grinding balls [h 1] trade-off is one of the major benefits of robust control—by / fraction of SAG mill's critical speed setting the stability/performance requirements the control rmax maximum singular value engineer is indirectly setting how aggressive the controller can be

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

– is it really 'critical size'? fine medium effect of SAG mill speed on breakage rates Are pebbles worth returning to the mill? they have proven themselves to be – hard resilient and challenging – a substantial percentage of mill feed – can increase coarse fraction current SAG mill

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 0 40 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 0 10 rpm)

sag mill filling up with ore sag mill filling up with ore atithipalace Heat Dissipation In Sag Mills For Mineral Grinding heat dissipation in sag mills for Heat Dissipation In Sag Mills For

model) as a fraction of the mill diameter (D) δc is modelled empirically as function of operating variables as follows: [3] J: Total load volume as a fraction of total mill volume N: Mill Speed as a percentage of the Critical Speed ∆J: governs the strength of the dependence of δc

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