For instance a mill of 300tph with a 300% recirculating load would have 1200 tph going through effectively, but if we reduce the recirculating load to 200% at 900 tph it will not change the power calculation. However if we increase the fresh feed by 100 TPH the power calculation goes up as does the size of mill required.
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With high aspect ratio SAG mills total charge to ball charge ratio should be greater than 2 (up to ) for a coarse mill feed (say F80 > 110 mm). If the mill feed size is fine, say 50 mm or 30 mm, then you are looking at a total charge to ball charge ratio of about
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This is because the product size distribution from AG/SAG mills tends to have more fine material than the HPGR circuit product (Morrell, 2009; 2011) and hence need less ball mill power. Based on ...
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 ...
bling mills (AG/SAG, rod, and ball mills) involved in reducing the size of the primary crusher product to that of the final product (usually the cyclone overflow of the last stage of grinding prior to flotation/leaching). 2. Feed rate to the circuit (dry tonnes/h) 3. Power draw of the comminution equipment (kW)
In this example, the OWi of the SAG mill was found to be 30% higher than the ball mill, thus suggesting that the SAG mill was less efficient than the ball mill. The apparent inefficiency of SAG mills when using Bond analysis is widely understood to be due to the difference in the slopes of the size distributions. In contrast, when the SSE75 was ...
2. Background. The SAG grinding process has been modeled by various authors, either generating explanatory models of the grinding process, with the aim of modeling, simulating, and optimizing the individual process, as well as integrating it into aggregate processes, such as the minetomill (M2M) paradigm, a practice that has generated the capacity to analytically assess aspects of mining and ...
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 w...
In order to obtain the optimal operation parameters of a SAG mill, in this paper, the discrete element method (DEM) is used to simulate the breakage process of the particles by controlling...
The purpose of the primary crusher is to reduce the ROM ore to a size amenable for feeding the secondary crusher or the SAG mill grinding circuit. The ratio of reduction through a primary crusher can be up to about 8:1. Feed: ROM up to m. Product: 300mm (for transport) to 200mm (for SAG mill) Feed Rate:
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' () in diameter, powered by a 28 MW (38,000 HP) motor. A SAG mill with a 44' () diameter and a power of 35 MW (47,000 HP) has been designed. Attrition between grinding balls and ore particles causes grinding of ...
Three methods of lab testing are best suitable for sizing SAG mills and accu rate determination of parameters of the mill drives: Barratt—Doll method based on the Bond work index es [3]; JK Drop Weight/SMC developed by JKMRC [4]; Starkey's method SAGDesign/SPI [5].
A Cerro Verde expansion used a similar flowsheet as the 2006commissioned circuit to triple circuit capacity. The expansion circuit includes eight MP1250 cone crushers, eight HPGRs (also x units, with 5 MW each), and six ball mills (22 MW each), for installed comminution power of 180 MW. and a nameplate capacity of 240,000 tpd.
Methods to Estimate AG/SAG Mill Grinding Power Requirements (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) (3) Using Don Burgess' method (11th Mill Operators Conference 2012)
The power drawn from a cylindrical (shellsupported) mill is given by Equation 1. . 1 1 Where: A and K are empirical fitting factors D is the mill diameter inside the liners, m % . 1,. (1) Jx is the mill filling of component x, L is the mill effective grinding length, m as a fraction of total mill volume ( for 30%)
V — Effective volume of ball mill, m3; G2 — Material less than in product accounts for the percentage of total material, %; G1 — Material less than in ore feeding accounts for in the percentage of the total material, %; q'm — Unit productivity calculated according to the new generation grade (), t/(). The values of q'm are determined by ...
approach to modeling of mill power draw. Trans. Instn. Mining. Metall. (Sect C:Mineral Processing Extr Metall.) 105, JanuaryApril 1996 ppC54C62. Austin LG A mill power equation for SAG mills. Minerals and Metallurgical Processing. Feb 1990 pp5762. Gross power No load power Net power drawn by the charge () The net power is calculated from ...
The effective power draw calculated using the Bond (1961) formula therefore encompasses the inefficiencies of the laboratory mill in comparison to the pilot mill. Since the closing screen and net grams per revolution is used to calculate the BBWi, there is a relationship between BBWi and the effective energy efficiency of the laboratory mill ...
Mill Power required at pinionshaft = (240 x x ) ÷ = 5440 Hp Speed reducer efficiency: 98% 5440 Hp ÷ = 5550 HP (required minimum motor output power). Therefore select a mill to draw at least 5440 Hp at the pinionshaft. Based upon the pilot plant test results, the volumetric loading for the mill can be determined.
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