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the correct power required to grind ore in a SAG mill, by developing ore hardness variability functions for the ore body to be mined. This paper describes the next step in the SAG design process, which is choosing a SAG mill to accomplish the required specified design performance.
Read More →COPPER MOUNTAIN: OVERVIEW ON THE GRINDING MILLS AND THEIR DUAL PINION MILL DRIVES ABSTRACT This paper will first give a short overview of the Copper Mountain project in British Columbia, which just has started commercial operation earlier this year. The grinding process with one 34' x 20' SAG
Read More →Oct 05, 2010· It is situated near the Newmont Yanacocha gold mine, where installed what was then the world's largest single-stage SAG mill, a 32ft x 32ft (9.75m x 9.75m) EGL mill, driven by a 16.5MW ABB gearless motor, in 2008. That mill design was also the first of its kind and was customized for Newmont.
Read More →CURRENT TRENDS IN SAG AND AG MILL OPERABILITY AND CONTROL. ... required to get the SAG mill back to the required operating . ... harder by operating the mill at a higher speed range.
Read More →E&MJ reported in October 2010 (See "SAG Mill Gearless Drives Go to South American Projects,"p. 102) ABB Group's Minerals Division had won an order from Newmont Mining Corp. to engineer three gearless mill drive (GMD) systems to be installed at its Yanacocha Minas Conga oxide copper-gold project in Peru.
Read More →Variable speed was required for the SAG mill. Various options were considered to meet the specified speed range of 65 to 85% of mill critical speed, and the final selection was the IES Hyper-Synchronous drive Slip Energy Recovery (SER), in conjunction with Wound Rotor Induction motors (WRIM).
Read More →Feb 12, 2020· The SAG Mill has four output slots; recipes can have 1-4 different outputs, with different chances of obtaining those outputs. Uniquely, the SAG Mill can use Grinding Balls made from various materials to increase energy efficiency (resulting in higher processing speed), increase bonus output chances, and add a chance to double all output. This ...
Read More →Motors & Drives; Ring gear drives huge grinding mill. By this summer, a grinding mill that is bigger around than a Boeing 747 will turn chunks of copper ore …
Read More →Therefore the SAG mill speed could not be controlled using the microphone based signal and instead was manually controlled/set by the control room operator. Thus operation/speed of the mill could and would change significantly based on a particular operator running the mill and their overall level of mill operation experience and skill.
Read More →Mill load sharing – Maintains equal torques on dual pinion mills throughout the whole speed range. Controlled rollback – Prevents backlash and reduces downtime. Mill power ride through – Keeps the mill operating even under voltage dips. Over-duty cycle – Avoids unexpected downtime if the mill gets overloaded.
Read More →Modelling SAG milling power and speciﬁc energy consumption including the feed percentage of intermediate size particles ... the SAG mill critical speed; Pc = SAG mill power consumption (kW); % 600 +100 = % of the fresh feed in the size range 152 +25 mm. M. Silva, A. Casali/Minerals Engineering 70 (2015) 156–161 157.
Read More →They can be furnished with adjustable frequency drives (PWM, LCI, and Cyclo-converter) for soft starters or speed regulation. With all of the advancements made in adjustable frequency drive technology, the variable speed synchronous motor is a logical choice for applications requiring high torque at low speed with a high-speed range.
Read More →especially in fixed speed mills. Often selected when low steel contamination is required. 2 AG mill + a recycle crusher Competent ore - relatively homogenous (the recycle crusher is used to balance the rate of impact breakage within the circuit) 3 SAG mill (8 – 15% ball charge) Variable competency ore 4 High ball charge SAG mill (15 to 25% ball
Read More →In recognition of ore variability, many current SAG mills are installed with variable speed drives, capable of operating the mill through a wide and continuous range of speed values. Mill speed and liner profile determine grinding media trajectories, as shown in Figure 1. By increasing mill speed or the steepness of liner attack angle,
Read More →Most mills used in mining rely on impact to breakdown rock to a suitable size for downstream processing. The impact can be rock on rock such as in an Autogenous Grinding (AG) mill, rock and a small ball charge (~10%), used in Semi Autogenous Grind...
Read More →According to available literature, the operating speeds of AG mills are much higher than conventional tumbling mills and are in the range of 80–85% of the critical speed. SAG mills of comparable size but containing say 10% ball charge (in addition to the rocks), normally, operate between 70 and 75% of the critical speed.
Read More →Figure 8.3 Simplified calculation of the torque required to turn a mill. RI FULWLFDO VSHHG 3RZHU Figure 8.4 The effect of mill speed on the power drawn by a rotating mill. The liner profile and the stickiness of the pulp in the mill can have a significant effect on the actual critical velocity. Mills usually operate in the range 65 - 82% of ...
Read More →Jun 20, 2015· Ball Mill Critical Speed & Working Principle ... The only assumptions required for determination of the single ball trajectory are a coefficient of friction between the ball and mill lining, and ...
Read More →SAG is an acronym for semi-autogenous grinding. SAG mills are autogenous mills that also 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' (12.8m) in diameter, powered by a 28 MW (38,000 HP) motor.
Read More →In my experience, SAG Mills are normally variable speed, and Ball Mills are normally fixed speed. There are multiple ways to provide variable speed, the common ones are WRIM+LRS+SER or SCIM+VSD, the top of the range is gearless mill drives.
Read More →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.
Read More →Optimising the capacity of your SAG mill is crucial to avoiding downtime and liner wear and damage. With variances in mill ore feed rate, mill speed and slurry density, critical impacts can occur in your SAG mill. The speed at which these variances are adjusted for is thus crucial for minimizing damage and optimizing liner life.
Read More →Go gearless to meet your business objetives by exceeding standard availability targets in your grinding operations. ABB's GMD is the most powerful mill drive system in the market to power semiautogenous (SAG), ball and autogenous (AG) mills, This 'workhorse' for grinding operations combines a robust, service-friendly and fit for purpose ...
Read More →Milling curves as a tool for characterising SAG mill performance ... as sometimes required for ... and given as a function of mill speed. The wide range of milling configurations coupled with ...
Read More →MW). It has been the industry standard for SAG mills above 13 MW capacity. However, pinion systems to 8 MW per pinion and dual motor systems with quadruple pinions extend the range of gear driven mills to a theoretical limit of 32 MW. The Ernest Henry SAG mill (11 MW) is currently the largest twin pinion single drive mill installed in Australia.
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