AG & SAG Mill Grinding Compared Which is Best Ores ground have ranged in power requirements from 2 3 Hph/lt for an 8 14 mesh grind up to 20 30 Hph/lt for a 48 65 mesh grind Where dry grinding has been adopted Aerofall Mills have been exclusively used They are characterized by a length that varies little ranging from
The SAG mill power does not increase with an increase in the mill speed ratio but when the speed reaches about 85% of the critical mill speed the power decreases and the mill power increases
During a mill circuit survey the power to the no 2 SAG mill was found to have dropped by despite load creeping up and ederate increasing at the onset of the power drop and then being maintained Figure 2 Upon inspection of the mill after a crash stop it was found to be dramatically slurry pooling 9000 450 SAG 2 Power Loadx100 8500 400
Taking care of a SAG mill through proper maintenance and repair is vital for long term reliability and efficiency in copper ore mining operations Real life Examples of SAG Mills in Copper Ore Mining SAG mills have been a critical component in the copper ore mining process for many years
Attempts to continuously sample and measure the significant variables of the secondary mill discharge are also open to question As a result the mill operator is left with the power draw on the secondary mill motor as the only positive measurement of a process variable to guide him in operation and control of the circuit
The document presents a mill power equation for semiautogenous SAG mills It develops an equation that calculates mill power based on factors like mill diameter length charge loading characteristics ball and rock densities and fraction of critical speed The equation accounts for both the kinetic energy of material moving in a locked path within the mill as well
The main grinding circuit at Les Mines Selbaie consists of two mills one SAG mill in closed circuit with an 8 x 20 vibrating screen with 700 micron deck and one ball mill The SAG mill is 27 diameter x long The Holt McDermott grinding circuit uses a large primary SAG mill which is diameter x
There are few methods of semi autogenous SAG mill power prediction in the full scale without using long experiments In this work the effects of different operating parameters such as feed moisture mass flowrate mill load cell mass SAG mill solid percentage inlet and outlet water to the SAG mill and work index are studied A total number of 185 full scale SAG
There are two parts to SAG mill design best practices First is to choose the SAG mill chamber size and power discussed above that will process the design feed every day including those days when mostly hard ore is available Second is to engineer the grinding plant so that optimization can be done quickly
The aspect ratio mill diameter/mill length of autogenous and semi autogenous mills varies widely and can be as high as three or as low as
SAG MILL TESTING AN OVERVIEW OF THE TEST PROCEDURES AVAILABLE TO CHARACTERIZE ORE GRINDABILITY AUTHOR VERRET G CHIASSON AND A MCKEN SGS KEYWORDS Comminution grindability grinding SAG mill AG mill milling HPGR work index pilot plant INTRODUCTION The resistance of ore samples to
SAG mill base power was estimated from pilot plant data at kWh/t the basis was a SABC circuit of 8% ball charge Maximum SAG mill power was determined by deducting the installed ball mill pinion power of kWh/t from the maximum overall circuit power of
A group was recently discussing this by asking I ve tried to estimate AG/SAG Mill power requirements using several different methods 1 Using the results of SMC data 2 Using SAG Power Index SPI data 3 Using the 1989 Barratt method updated on Alex Doll s Web site February 16 2015
• Phu Kham SAG Mill liner performance as basis of analysis • Analysis assumptions Same tonnes processed Similar rate of mass loss • Lower lifter height = increased mill volume = higher power draw Which is Better 170 days % 2100 t/h 2700 t/h <97% <150 days Which is Better Baseline 170 days 3% <150 days 27% Takeaway
where m p is in kW; D is internal mill diameter meters L is internal mill length meters ; J is total fractional charge loading of the mill; J B is the fractional mill filling by balls; ε B is the effective porosity of the charge taken as ; ρ s and ρ b are true densities of rock and balls tons per cubic meter respectively; w c is the weight fraction of rock in water and rock in
Due to its strong lifting capacity and excellent grinding performance the trapezoidal liner is widely used in the SAG mill The structure of the trapezoidal liner is shown in Fig 1 the main dimensions are dip angle tau length of the top edge L and height h Dip angle tau determines the trajectory of the mediums in the SAG mill which directly affects
performing SAG mill It is possible in some cases to modify a SAG circuit to force it to perform better but this often takes time much effort and costly modifications In most cases the capital spent on a properly sized SAG mill may prevent production losses that would be many times greater over the extended start up period
SAG mill liner development draws primarily on practical experience from SAG milling operations supported by computer based modeling of charge motion in SAG mills and on established good design practice Liner design needs to respond to the process aspects of mill liner action that are critical to good SAG mill performance the impact of shell liners on the
SAG mills are distinguished by utilising run of mine RoM feed as grinding media with 5 18% steel balls added to supplement grinding Mill power MW
The simulation model used for the analysis included several interacting constraints including 1 estimation of reline periods based on the Bond abrasion index geometallurgical model mill power
Development of an equation for tumbling charge and balls plus comparison to plant data suggests that the net mill power for cylindrical semiautogenous mills can be calculated from $${m p} = {D^{}}Lleft {1 } right left[ {left {1 {varepsilon B}} right left {{rho s}/{w o}} right J {J B}left {{rho b} {rho s}/{w c}} right } right]left {{phi c
Similar to the impeller design affecting pump capacity the pulp lifter design affects the discharge capacity or mill throughput of AG and SAG grinding mills Generally the discharge from AG/SAG mills consists of one or both of the following components slurry water and finer particles and pebbles 20 100 mm Single stage AG/SAG mills
The aspect ratio mill diameter/mill length of autogenous and semi autogenous mills varies widely and can be as high as three or as low as
